Freescale MC9S12HZ256J3CAA Hcs12 microcontroller Datasheet

MC9S12HZ256
Data Sheet
Covers
MC9S12HZ128, MC9S12HZ64, MC9S12HN64
MC3S12HZ256, MC3S12HZ128, MC3S12HZ64,
MC3S12HN64, MC3S12HZ32 & MC3S12HN32
HCS12
Microcontrollers
MC9S12HZ256V2
Rev. 2.04
10/2006
freescale.com
MC9S12HZ256 Data Sheet
MC9S12HZ256V2
Rev. 2.04
10/2006
To provide the most up-to-date information, the revision of our documents on the World Wide Web will be
the most current. Your printed copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://freescale.com/
The following revision history table summarizes changes contained in this document.
Revision History
Date
Revision
Level
October 10, 2005
02.01
New Data Sheet
02.02
Corrected Table 4-1 Port U and Port V descriptions
Added 80QFP to PCB layout guidelines
Added derivative differences to appendix D
Updated ordering information on appendix E
October 5, 2006
02.03
Added ROM to memory options
Updated memory map figures and added tables for RAM mapping options
Added ROM derivatives to appendix D
Added ROM description to appendices (appendix E)
October 31, 2006
02.04
Added MC3S12HZ64 mask set
Updated Table A-5 Thermal Package Characteristics
Updated Table A-17 PLL Characteristics
April 20, 2006
Description
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
This product incorporates SuperFlash® technology licensed from SST.
© Freescale Semiconductor, Inc., 2006. All rights reserved.
MC9S12HZ256 Data Sheet, Rev. 2.04
4
Freescale Semiconductor
Chapter 1
MC9S12HZ256 Device Overview . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 2
256 Kbyte Flash Module (FTS256K2V1) . . . . . . . . . . . . . . . . . . 57
Chapter 3
2 Kbyte EEPROM Module (EETS2KV1). . . . . . . . . . . . . . . . . . . 95
Chapter 4
Port Integration Module (PIM9HZ256V2) . . . . . . . . . . . . . . . . 115
Chapter 5
Clocks and Reset Generator (CRGV4) . . . . . . . . . . . . . . . . . . 167
Chapter 6
Oscillator (OSCV2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Chapter 7
Analog-to-Digital Converter (ATD10B16CV4) . . . . . . . . . . . . 207
Chapter 8
Liquid Crystal Display (LCD32F4BV1) . . . . . . . . . . . . . . . . . . 241
Chapter 9
Motor Controller (MC10B8CV1). . . . . . . . . . . . . . . . . . . . . . . . 259
Chapter 10
Stepper Stall Detector (SSDV1). . . . . . . . . . . . . . . . . . . . . . . . 291
Chapter 11
Inter-Integrated Circuit (IICV2) . . . . . . . . . . . . . . . . . . . . . . . . 309
Chapter 12
Freescale’s Scalable Controller Area Network (MSCANV2) . 333
Chapter 13
Serial Communication Interface (SCIV4) . . . . . . . . . . . . . . . . 387
Chapter 14
Serial Peripheral Interface (SPIV3) . . . . . . . . . . . . . . . . . . . . . 419
Chapter 15
Pulse-Width Modulator (PWM8B6CV1). . . . . . . . . . . . . . . . . . 441
Chapter 16
Timer Module (TIM16B8CV1) . . . . . . . . . . . . . . . . . . . . . . . . . . 475
Chapter 17
Dual Output Voltage Regulator (VREG3V3V2). . . . . . . . . . . . 501
Chapter 18
Background Debug Module (BDMV4). . . . . . . . . . . . . . . . . . . 509
Chapter 19
Debug Module (DBGV1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
Chapter 20
Interrupt (INTV1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
Chapter 21
Multiplexed External Bus Interface (MEBIV3) . . . . . . . . . . . . 575
Chapter 22
Module Mapping Control (MMCV4) . . . . . . . . . . . . . . . . . . . . . 603
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
5
Appendix A Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
Appendix B PCB Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655
Appendix C Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 658
Appendix D Derivative Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 661
Appendix E ROM Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 662
Appendix F Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 666
Appendix G Detailed Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 667
MC9S12HZ256 Data Sheet, Rev. 2.04
6
Freescale Semiconductor
Chapter 1
MC9S12HZ256 Device Overview
1.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.2 Device Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.3 Part ID Assignments and Mask Set Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.4 Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.4.1 Device Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.4.2 Signal Properties Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.5 Detailed Signal Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.5.1 EXTAL, XTAL — Oscillator Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.5.2 RESET — External Reset Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.5.3 TEST — Test Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.5.4 XFC — PLL Loop Filter Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.5.5 BKGD / TAGHI / MODC — Background Debug, Tag High, and Mode Pin . . . . . . . . . 38
1.5.6 Port Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.5.7 Power Supply Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
1.6 System Clock Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
1.7 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
1.7.1 Normal Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
1.7.2 Special Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
1.8 Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
1.8.1 Securing the Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
1.8.2 Operation of the Secured Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
1.8.3 Unsecuring the Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
1.9 Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
1.10 Resets and Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
1.10.1 Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
1.10.2 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
1.10.3 Effects of Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
7
Chapter 2
256 Kbyte Flash Module (FTS256K2V1)
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.1.1 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.1.3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
2.1.4 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
2.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
2.4.1 Flash Command Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
2.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
2.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
2.5.3 Background Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Flash Module Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
2.6.1 Unsecuring the MCU using Backdoor Key Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
2.6.2 Unsecuring the Flash Module in Special Single-Chip Mode using BDM . . . . . . . . . . . . 93
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2.7.1 Flash Reset Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2.7.2 Reset While Flash Command Active . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2.8.1 Description of Flash Interrupt Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Chapter 3
2 Kbyte EEPROM Module (EETS2KV1)
3.1
3.2
3.3
3.4
3.5
3.6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.1.1 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
3.1.3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.1.4 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
3.4.1 Program and Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
3.5.1 Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
3.5.2 Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
3.5.3 Background Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
MC9S12HZ256 Data Sheet, Rev. 2.04
8
Freescale Semiconductor
3.7
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Chapter 4
Port Integration Module (PIM9HZ256V2)
4.1
4.2
4.3
4.4
4.5
4.6
lntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.1.2 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
4.3.1 Port AD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.3.2 Port L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
4.3.3 Port M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
4.3.4 Port P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
4.3.5 Port S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
4.3.6 Port T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
4.3.7 Port U . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
4.3.8 Port V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4.4.1 I/O Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4.4.2 Input Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4.4.3 Data Direction Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4.4.4 Reduced Drive Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
4.4.5 Pull Device Enable Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
4.4.6 Polarity Select Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
4.4.7 Pin Configuration Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
4.5.1 Reset Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
4.6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
4.6.2 Interrupt Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
4.6.3 Operation in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Chapter 5
Clocks and Reset Generator (CRGV4)
5.1
5.2
5.3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
5.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
5.2.1 VDDPLL, VSSPLL — PLL Operating Voltage, PLL Ground . . . . . . . . . . . . . . . . . . . . . . 169
5.2.2 XFC — PLL Loop Filter Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
5.2.3 RESET — Reset Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
5.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
9
5.4
5.5
5.6
5.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
5.4.1 Phase Locked Loop (PLL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
5.4.2 System Clocks Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
5.4.3 Clock Monitor (CM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
5.4.4 Clock Quality Checker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
5.4.5 Computer Operating Properly Watchdog (COP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
5.4.6 Real-Time Interrupt (RTI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
5.4.7 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
5.4.8 Low-Power Operation in Run Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
5.4.9 Low-Power Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
5.4.10 Low-Power Operation in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
5.5.1 Clock Monitor Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
5.5.2 Computer Operating Properly Watchdog (COP) Reset . . . . . . . . . . . . . . . . . . . . . . . . . 200
5.5.3 Power-On Reset, Low Voltage Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
5.6.1 Real-Time Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
5.6.2 PLL Lock Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
5.6.3 Self-Clock Mode Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Chapter 6
Oscillator (OSCV2)
6.1
6.2
6.3
6.4
6.5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
6.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
6.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
6.2.1 VDDPLL and VSSPLL — PLL Operating Voltage, PLL Ground . . . . . . . . . . . . . . . . . . . 204
6.2.2 EXTAL and XTAL — Clock/Crystal Source Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
6.2.3 XCLKS — Colpitts/Pierce Oscillator Selection Signal . . . . . . . . . . . . . . . . . . . . . . . . . 205
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
6.4.1 Amplitude Limitation Control (ALC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
6.4.2 Clock Monitor (CM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
MC9S12HZ256 Data Sheet, Rev. 2.04
10
Freescale Semiconductor
Chapter 7
Analog-to-Digital Converter (ATD10B16CV4)
7.1
7.2
7.3
7.4
7.5
7.6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
7.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
7.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
7.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
7.2.1 ANx (x = 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) — Analog Input Channel x Pins
209
7.2.2 ETRIG3, ETRIG2, ETRIG1, ETRIG0 — External Trigger Pins . . . . . . . . . . . . . . . . . 209
7.2.3 VRH, VRL — High Reference Voltage Pin, Low Reference Voltage Pin . . . . . . . . . . . . 209
7.2.4 VDDA, VSSA — Analog Circuitry Power Supply Pins . . . . . . . . . . . . . . . . . . . . . . . . . 209
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
7.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
7.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
7.4.1 Analog Sub-block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
7.4.2 Digital Sub-Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
7.4.3 Operation in Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Chapter 8
Liquid Crystal Display (LCD32F4BV1)
8.1
8.2
8.3
8.4
8.5
8.6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
8.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
8.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
8.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
8.2.1 BP[3:0] — Analog Backplane Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
8.2.2 FP[31:0] — Analog Frontplane Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
8.2.3 VLCD — LCD Supply Voltage Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
8.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
8.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
8.4.1 LCD Driver Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
8.4.2 Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
8.4.3 Operation in Pseudo Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
8.4.4 Operation in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
8.4.5 LCD Waveform Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
11
Chapter 9
Motor Controller (MC10B8CV1)
9.1
9.2
9.3
9.4
9.5
9.6
9.7
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
9.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
9.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
9.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
9.2.1 M0C0M/M0C0P/M0C1M/M0C1P — PWM Output Pins for Motor 0 . . . . . . . . . . . . 262
9.2.2 M1C0M/M1C0P/M1C1M/M1C1P — PWM Output Pins for Motor 1 . . . . . . . . . . . . 262
9.2.3 M2C0M/M2C0P/M2C1M/M2C1P — PWM Output Pins for Motor 2 . . . . . . . . . . . . 262
9.2.4 M3C0M/M3C0P/M3C1M/M3C1P — PWM Output Pins for Motor 3 . . . . . . . . . . . . 263
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
9.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
9.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
9.4.1 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
9.4.2 PWM Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
9.4.3 Motor Controller Counter Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
9.4.4 Output Switching Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
9.4.5 Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
9.4.6 Operation in Stop and Pseudo-Stop Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
9.6.1 Timer Counter Overflow Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Initialization/Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
9.7.1 Code Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
Chapter 10
Stepper Stall Detector (SSDV1)
10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
10.1.1 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
10.1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
10.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
10.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
10.2.1 COSxM/COSxP — Cosine Coil Pins for Motor x . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
10.2.2 SINxM/SINxP — Sine Coil Pins for Motor x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
10.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
10.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
10.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
10.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
10.4.1 Return to Zero Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
10.4.2 Full Step States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302
10.4.3 Operation in Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
10.4.4 Stall Detection Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
MC9S12HZ256 Data Sheet, Rev. 2.04
12
Freescale Semiconductor
Chapter 11
Inter-Integrated Circuit (IICV2)
11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
11.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309
11.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
11.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310
11.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
11.2.1 IIC_SCL — Serial Clock Line Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
11.2.2 IIC_SDA — Serial Data Line Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
11.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
11.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
11.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
11.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
11.4.1 I-Bus Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
11.4.2 Operation in Run Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
11.4.3 Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
11.4.4 Operation in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
11.5 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
11.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
11.7 Initialization/Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
11.7.1 IIC Programming Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Chapter 12
Freescale’s Scalable Controller Area Network (MSCANV2)
12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
12.1.1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
12.1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
12.1.3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
12.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
12.2.1 RXCAN — CAN Receiver Input Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
12.2.2 TXCAN — CAN Transmitter Output Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
12.2.3 CAN System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
12.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
12.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
12.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
12.3.3 Programmer’s Model of Message Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
12.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367
12.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367
12.4.2 Message Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368
12.4.3 Identifier Acceptance Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
12.4.4 Timer Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
12.4.5 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378
12.4.6 Low-Power Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378
12.4.7 Reset Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
13
12.4.8 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
12.5 Initialization/Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
12.5.1 MSCAN initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
Chapter 13
Serial Communication Interface (SCIV4)
13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
13.1.1 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
13.1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
13.1.3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
13.1.4 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
13.2 External Signal Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
13.2.1 TXD — SCI Transmit Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
13.2.2 RXD — SCI Receive Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
13.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
13.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
13.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
13.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400
13.4.1 Infrared Interface Submodule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
13.4.2 Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
13.4.3 Baud Rate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403
13.4.4 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404
13.4.5 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
13.4.6 Single-Wire Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
13.4.7 Loop Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416
13.5 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416
13.5.1 Description of Interrupt Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417
13.5.2 Recovery from Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418
Chapter 14
Serial Peripheral Interface (SPIV3)
14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
14.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
14.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419
14.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420
14.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420
14.2.1 MOSI — Master Out/Slave In Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420
14.2.2 MISO — Master In/Slave Out Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
14.2.3 SS — Slave Select Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
14.2.4 SCK — Serial Clock Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
14.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
14.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421
14.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422
14.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429
MC9S12HZ256 Data Sheet, Rev. 2.04
14
Freescale Semiconductor
14.4.1 Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 430
14.4.2 Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
14.4.3 Transmission Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432
14.4.4 SPI Baud Rate Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435
14.4.5 Special Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436
14.4.6 Error Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437
14.4.7 Operation in Run Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438
14.4.8 Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438
14.4.9 Operation in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438
14.5 Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
14.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
14.6.1 MODF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
14.6.2 SPIF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
14.6.3 SPTEF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
Chapter 15
Pulse-Width Modulator (PWM8B6CV1)
15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
15.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
15.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
15.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
15.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
15.2.1 PWM5 — Pulse Width Modulator Channel 5 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
15.2.2 PWM4 — Pulse Width Modulator Channel 4 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
15.2.3 PWM3 — Pulse Width Modulator Channel 3 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
15.2.4 PWM2 — Pulse Width Modulator Channel 2 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
15.2.5 PWM1 — Pulse Width Modulator Channel 1 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
15.2.6 PWM0 — Pulse Width Modulator Channel 0 Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
15.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
15.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443
15.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445
15.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
15.4.1 PWM Clock Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
15.4.2 PWM Channel Timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466
15.5 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
15.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
15
Chapter 16
Timer Module (TIM16B8CV1)
16.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475
16.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475
16.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475
16.1.3 Block Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476
16.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478
16.2.1 IOC7 — Input Capture and Output Compare Channel 7 Pin . . . . . . . . . . . . . . . . . . . . 478
16.2.2 IOC6 — Input Capture and Output Compare Channel 6 Pin . . . . . . . . . . . . . . . . . . . . 478
16.2.3 IOC5 — Input Capture and Output Compare Channel 5 Pin . . . . . . . . . . . . . . . . . . . . 478
16.2.4 IOC4 — Input Capture and Output Compare Channel 4 Pin . . . . . . . . . . . . . . . . . . . . 478
16.2.5 IOC3 — Input Capture and Output Compare Channel 3 Pin . . . . . . . . . . . . . . . . . . . . 478
16.2.6 IOC2 — Input Capture and Output Compare Channel 2 Pin . . . . . . . . . . . . . . . . . . . . 479
16.2.7 IOC1 — Input Capture and Output Compare Channel 1 Pin . . . . . . . . . . . . . . . . . . . . 479
16.2.8 IOC0 — Input Capture and Output Compare Channel 0 Pin . . . . . . . . . . . . . . . . . . . . 479
16.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 479
16.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 479
16.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 481
16.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495
16.4.1 Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 496
16.4.2 Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
16.4.3 Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
16.4.4 Pulse Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
16.4.5 Event Counter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
16.4.6 Gated Time Accumulation Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
16.5 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
16.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
16.6.1 Channel [7:0] Interrupt (C[7:0]F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
16.6.2 Pulse Accumulator Input Interrupt (PAOVI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
16.6.3 Pulse Accumulator Overflow Interrupt (PAOVF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
16.6.4 Timer Overflow Interrupt (TOF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
Chapter 17
Dual Output Voltage Regulator (VREG3V3V2)
17.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501
17.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501
17.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501
17.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502
17.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503
17.2.1 VDDR — Regulator Power Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503
17.2.2 VDDA, VSSA — Regulator Reference Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503
17.2.3 VDD, VSS — Regulator Output1 (Core Logic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
17.2.4 VDDPLL, VSSPLL — Regulator Output2 (PLL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
17.2.5 VREGEN — Optional Regulator Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
MC9S12HZ256 Data Sheet, Rev. 2.04
16
Freescale Semiconductor
17.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
17.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
17.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505
17.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505
17.4.1 REG — Regulator Core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505
17.4.2 Full-Performance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
17.4.3 Reduced-Power Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
17.4.4 LVD — Low-Voltage Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
17.4.5 POR — Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
17.4.6 LVR — Low-Voltage Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
17.4.7 CTRL — Regulator Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506
17.5 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
17.5.1 Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
17.5.2 Low-Voltage Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
17.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
17.6.1 LVI — Low-Voltage Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
Chapter 18
Background Debug Module (BDMV4)
18.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509
18.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509
18.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510
18.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510
18.2.1 BKGD — Background Interface Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
18.2.2 TAGHI — High Byte Instruction Tagging Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
18.2.3 TAGLO — Low Byte Instruction Tagging Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
18.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512
18.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512
18.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513
18.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518
18.4.1 Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518
18.4.2 Enabling and Activating BDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518
18.4.3 BDM Hardware Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519
18.4.4 Standard BDM Firmware Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
18.4.5 BDM Command Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521
18.4.6 BDM Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
18.4.7 Serial Interface Hardware Handshake Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
18.4.8 Hardware Handshake Abort Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
18.4.9 SYNC — Request Timed Reference Pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
18.4.10Instruction Tracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
18.4.11Instruction Tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532
18.4.12Serial Communication Time-Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532
18.4.13Operation in Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533
18.4.14Operation in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
17
Chapter 19
Debug Module (DBGV1)
19.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
19.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
19.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537
19.1.3 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537
19.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539
19.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540
19.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540
19.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540
19.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555
19.4.1 DBG Operating in BKP Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555
19.4.2 DBG Operating in DBG Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557
19.4.3 Breakpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564
19.5 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
19.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
Chapter 20
Interrupt (INTV1)
20.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
20.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568
20.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568
20.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
20.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
20.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
20.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
20.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
20.4.1 Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
20.5 Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
20.6 Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
20.6.1 Interrupt Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
20.6.2 Highest Priority I-Bit Maskable Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
20.6.3 Interrupt Priority Decoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
20.7 Exception Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573
Chapter 21
Multiplexed External Bus Interface (MEBIV3)
21.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575
21.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575
21.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
21.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 577
21.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579
21.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580
21.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580
MC9S12HZ256 Data Sheet, Rev. 2.04
18
Freescale Semiconductor
21.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
21.4.1 Detecting Access Type from External Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
21.4.2 Stretched Bus Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597
21.4.3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597
21.4.4 Internal Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602
21.4.5 Low-Power Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 602
Chapter 22
Module Mapping Control (MMCV4)
22.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603
22.1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
22.1.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
22.2 External Signal Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
22.3 Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
22.3.1 Module Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
22.3.2 Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606
22.4 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615
22.4.1 Bus Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615
22.4.2 Address Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616
22.4.3 Memory Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 617
Appendix A
Electrical Characteristics
A.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
A.1.1 Parameter Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
A.1.2 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
A.1.3 Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624
A.1.4 Current Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
A.1.5 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
A.1.6 ESD Protection and Latch-up Immunity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626
A.1.7 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 627
A.1.8 Power Dissipation and Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 628
A.1.9 I/O Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
A.1.10 Supply Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
A.2 ATD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
A.2.1 ATD Operating Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
A.2.2 Factors influencing accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
A.2.3 ATD accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634
A.3 NVM, Flash and EEPROM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 636
A.3.1 NVM timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 636
A.3.2 NVM Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 638
A.4 Voltage Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
A.4.1 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
A.4.2 Chip Power-up and Voltage Drops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 639
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
19
A.5
A.6
A.7
A.8
A.9
A.4.3 Output Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640
Reset, Oscillator and PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
A.5.1 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
A.5.2 Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643
A.5.3 Phase Locked Loop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 644
MSCAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 648
SPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 648
A.7.1 Master Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 648
A.7.2 Slave Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650
LCD_32F4B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651
External Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 651
Appendix B
PCB Layout Guidelines
Appendix C
Package Information
C.1 112-Pin LQFP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
C.2 80-Pin QFP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 660
Appendix D
Derivative Differences
Appendix E
ROM Description
E.1
E.2
Memory Map and Register Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 662
E.1.1 ROM Options Register (ROPT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 662
E.1.2 ROM Configuration Register (RCNFG). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 663
E.1.3 Device SC Number Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
E.1.4 Non-volatile Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664
ROM Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665
E.2.1 Security and Backdoor Key Access definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665
E.2.2 Unsecuring the MCU using the Backdoor Key Access . . . . . . . . . . . . . . . . . . . . . . . . . 665
Appendix F
Ordering Information
Appendix G
Detailed Register Map
MC9S12HZ256 Data Sheet, Rev. 2.04
20
Freescale Semiconductor
Chapter 1
MC9S12HZ256 Device Overview
1.1
Introduction
The MC9S12HZ256 microcontroller units (MCU) are 16-bit devices composed of standard on-chip
peripherals including a 16-bit central processing unit (HCS12 CPU), up to 256K bytes of Flash EEPROM
or ROM, up to 12K bytes of RAM, 2K bytes of EEPROM, two asynchronous serial communications
interfaces (SCI), a serial peripheral interface (SPI), an IIC-bus interface (IIC), an 8-channel 16-bit timer
(TIM), a 16-channel, 10-bit analog-to-digital converter (ATD), a six-channel pulse width modulator
(PWM), and two CAN 2.0 A, B software compatible modules (MSCAN). In addition, they feature a 32x4
liquid crystal display (LCD) controller/driver, a pulse width modulator motor controller (MC) consisting
of 16 high current outputs suited to drive up to four stepper motors, and four stepper stall detectors (SSD)
to simultaneously calibrate the pointer position of each motor. System resource mapping, clock generation,
interrupt control, and external bus interfacing are managed by the HCS12 Core. The MC9S12HZ256 have
full 16-bit data paths throughout. The inclusion of a PLL circuit allows power consumption and
performance to be adjusted to suit operational requirements. In addition to the I/O ports available in each
module, 8 general-purpose I/O pins are available with interrupt and wake-up capability from stop or wait
mode.
For information regarding the HCS12 CPU instruction set, please see the HCS12 CPU Reference Manual,
Freescale document order number S12CPUV2.
1.1.1
•
Features
HCS12 core
– 16-bit HCS12 CPU
Upward compatible with M68HC11 instruction set
Interrupt stacking and programmer’s model identical to M68HC11
16-bit ALU
Instruction queue
Enhanced indexed addressing
– MEBI (multiplexed external bus interface)
– MMC (module mapping control)
– INT (interrupt control)
– DBG (debugger and breakpoints)
– BDM (background debug mode)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
21
Chapter 1 MC9S12HZ256 Device Overview
•
•
•
•
•
•
•
•
•
Memory
– 256K, 128K, 64K, 32K Flash EEPROM or ROM
– 2K, 1K byte EEPROM
– 12K, 6K, 4K, 2K byte RAM
CRG (low current oscillator, PLL, reset, clocks, COP watchdog, real time interrupt, clock monitor)
Analog-to-digital converter
– 16 channels, 10-bit resolution
– External conversion trigger capability
Two 1-Mbps, CAN 2.0 A, B software compatible modules
– Five receive and three transmit buffers
– Flexible identifier filter programmable as 2 x 32 bit, 4 x 16 bit or 8 x 8 bit
– Four separate interrupt channels for Rx, Tx, error and wake-up
– Low-pass filter wake-up function
– Loop-back for self test operation
Timer
– 16-bit main counter with 7-bit prescaler
– 8 programmable input capture or output compare channels
– Two 8-bit or one 16-bit pulse accumulators
6 PWM channels
– Programmable period and duty cycle
– 8-bit 6-channel or 16-bit 3-channel
– Separate control for each pulse width and duty cycle
– Center-aligned or left-aligned outputs
– Programmable clock select logic with a wide range of frequencies
– Fast emergency shutdown input
Serial interfaces
– Two asynchronous serial communications interfaces (SCI)
– Synchronous serial peripheral interface (SPI)
– Inter-integrated circuit interface (IIC)
Liquid crystal display (LCD) driver with variable input voltage
– Configurable for up to 32 frontplanes and 4 backplanes or general-purpose input or output
– 5 modes of operation allow for different display sizes to meet application requirements
– Unused frontplane and backplane pins can be used as general-purpose I/O
PWM motor controller (MC) with 16 high current drivers
– Each PWM channel switchable between two drivers in an H-bridge configuration
– Left, right and center aligned outputs
– Support for sine and cosine drive
– Dithering
– Output slew rate control
MC9S12HZ256 Data Sheet, Rev. 2.04
22
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
•
•
•
•
1.1.2
Four stepper stall detectors (SSD)
– Full step control during return to zero
– Voltage detector and integrator / sigma delta converter circuit
– 16-bit accumulator register
– 16-bit modulus down counter
112-pin LQFP and 80-pin QFP packages
– 85 I/O lines with 5-V input and drive capability
– 5-V A/D converter inputs
– 8 key wake up interrupts with digital filtering and programmable rising/falling edge trigger
Operation at 50 MHz equivalent to 25-MHz bus speed
Development support
– Single-wire background debug™ mode (BDM)
– Debugger and on-chip hardware breakpoints
Modes of Operation
User modes
• Normal and emulation operating modes
– Normal single-chip mode
– Normal expanded wide mode
– Normal expanded narrow mode
– Emulation expanded wide mode
– Emulation expanded narrow mode
• Special operating mode
– Special single-chip mode with active background debug mode
Low-power modes
• Stop mode
• Pseudo stop mode
• Wait mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
23
Chapter 1 MC9S12HZ256 Device Overview
Block Diagram
VDDR
PK7
PT0
PT1
PT2
PT3
PT4
PT5
PT6
PT7
AN8
AN9
AN10
AN11
AN12
AN13
AN14
AN15
FP16
FP17
FP18
FP19
FP28
FP29
FP30
FP31
FP20
FP21
FP22
R/W
LSTRB/TAGLO
NOACC/XCLKS
FP23
ECS/ROMCTL
FP24
FP25
FP26
FP27
IOC0
IOC1
IOC2
IOC3
IOC4
IOC5
IOC6
IOC7
PTAD
PW4
PW5
RXCAN0
TXCAN0
RXCAN1
TXCAN1
PM2
PM3
PM4
PM5
SCI0
RXD0
TXD0
SPI
MISO
MOSI
SCK
SS
M0COSM
M0COSP
M0SINM
M0SINP
M1COSM
M1COSP
M1SINM
M1SINP
PWM0
PWM1
PWM2
PWM3
M0C0M
M0C0P
M0C1M
M0C1P
M1C0M
M1C0P
M1C1M
M1C1P
PTM
DDRM
CAN1
PS0
PS1
DDRS
PTS
CAN0
SSD1
DDRAD
SDA
SCL
PTP
RXD1
PP0
PP1
PP2
PP3
PP4
PP5
DDRP
PW0
PW1
Pulse
PW2
Width
Modulator PW3
IIC
SSD0
MOTOR0,1, 2 3 Supply
SSD2
SSD3
PAD0
PAD1
PAD2
PAD3
PAD4
PAD5
PAD6
PAD7
TXD1
SCI1
PPAGE
Multiplexed Address/Data Bus
PTK
DDRK
DDRB
PTB
PTA
DDRA
ADDR8
ADDR9
ADDR10
ADDR11
ADDR12
ADDR13
ADDR14
ADDR15
PTL
PE2
PE3
PE7
FP8
FP9
FP10
FP11
FP12
FP13
FP14
FP15
LCD
Driver
ADDR0
ADDR1
ADDR2
ADDR3
ADDR4
ADDR5
ADDR6
ADDR7
DDRL
PL0
PL1
PL2
PL3
PL4
PL5
PL6
PL7
FP0
FP1
FP2
FP3
FP4
FP5
FP6
FP7
PIX0
PIX1
PIX2
PIX3
PTE
Multiplexed Multiplexed
Wide
Narrow
Bus
Bus
BP0
BP1
BP2
BP3
DDRE
PA0
PA1
PA2
PA3
PA4
PA5
PA6
PA7
System
Integration
Module
XIRQ
IRQ
ECLK
MODA
MODB
PTK
DATA8
DATA9
DATA10
DATA11
DATA12
DATA13
DATA14
DATA15
DATA0
DATA1
DATA2
DATA3
DATA4
DATA5
DATA6
DATA7
Periodic Interrupt
COP Watchdog
Clock Monitor
DDRK
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
PTT
DATA0
DATA1
DATA2
DATA3
DATA4
DATA5
DATA6
DATA7
DDRT
PK0
PK1
PK2
PK3
Clock and
Reset
Generation
Module
VLCD
VLCD
XADDR14
XADDR15
XADDR16
XADDR17
S12 CPU
Breakpoints
PTE
PE0
PE1
PE4
PE5
PE6
PLL
DDRE
XFC
VDDPLL
VSSPLL
EXTAL
XTAL
RESET
TEST
KWAD0
KWAD1
KWAD2
KWAD3
KWAD4
KWAD5
KWAD6
KWAD7
PTU
12K, 6K, 4K, 2K Bytes RAM
Single-Wire Background
Debug Module
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
AN8
AN9
AN10
AN11
AN12
AN13
AN14
AN15
DDRU
2K Bytes EEPROM
M2COSM
M2COSP
M2SINM
M2SINP
M3COSM
M3COSP
M3SINM
M3SINP
PWM4
PWM5
PWM6
PWM7
M2C0M
M2C0P
M2C1M
M2C1P
M3C0M
M3C0P
M3C1M
M3C1P
PTV
256K, 128K, 64K, 32K Bytes Flash or ROM
BKGD
VDDA
VSSA
VRH
VRL
VDDA
Analog to VSSA
VRH
Digital
Converter VRL
Voltage Regulator
VDD1
VSS1,2
DDRV
1.1.3
PS4
PS5
PS6
PS7
PU0
PU1
PU2
PU3
PU4
PU5
PU6
PU7
VDDM1,2,3
VSSM1,2,3
PV0
PV1
PV2
PV3
PV4
PV5
PV6
PV7
Input Capture and
Output Compare
Timer
Figure 1-1. MC9S12HZ256 Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
24
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.2
Device Memory Map
Table 1-1 shows the device memory map for the MC9S12HZ256 out of reset.
Table 1-1. Device Register Map Overview
Address
Offset
Module
Size
(Bytes)
0x0000–0x0017
HCS12 Core (Ports A, B, E, Modes, Inits, Test)
24
0x0018–0x0019
Reserved
2
0x001A–0x001B
Device ID register (PARTID)
2
0x001C–0x001F
HCS12 Core (MEMSIZ, IRQ, HPRIO)
4
0x0020–0x0027
Reserved
8
0x0028–0x002F
HCS12 Core (Background Debug Mode)
8
0x0030–0x0033
HCS12 Core (PPAGE, Port K)
4
0x0034–0x003F
Clock and Reset Generator (PLL, RTI, COP)
12
0x0040–0x006F
Standard Timer Module 16-bit 8 channels (TIM)
48
0x0070–0x007F
Reserved
16
0x0080–0x00AF
Analog-to-Digital Converter 10-bit 16 channels (ATD)
48
0x00B0–0x00BF
Reserved
16
0x00C0–0x00C7
Inter Integrated Circuit (IIC)
8
0x00C8–0x00CF
Serial Communications Interface 0 (SCI0)
8
0x00D0–0x00D7
Serial Communications Interface 1 (SCI1)
8
0x00D8–0x00DF
Serial Peripheral Interface (SPI)
8
0x00E0–0x00FF
Pulse Width Modulator 8-bit 6 channels (PWM)
32
0x0100–0x010F
Flash control registers
16
0x0110–0x011B
EEPROM control registers
12
0x011C–0x011F
Reserved
4
0x0120–0x0137
Liquid Crystal Display Driver 32x4 (LCD)
24
0x0140–0x017F
Scalable Controller Area Network 0 (MSCAN0)
64
0x0180–0x01BF
Scalable Controller Area Network 1 (MSCAN1)
64
0x01C0–0x01FF
Motor Control Module (MC)
64
0x0200–0x027F
Port Integration Module (PIM)
128
0x0280–0x0287
Reserved
8
0x0288–0x028F
Stepper Stall Detector 0 (SSD0)
8
0x0290–0x0297
Stepper Stall Detector 1 (SSD1)
8
0x0298–0x029F
Stepper Stall Detector 2 (SSD2)
8
0x02A0–0x02A7
Stepper Stall Detector 3 (SSD3)
8
0x02A8–0x03FF
Reserved
344
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
25
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-2 shows the device memory map for the MC9(3)S12HZ256 out of reset.
0x0000
0x0400
0x0000
1K Register Space
0x03FF
Mappable to any 2K Boundary
0x0000
2K Bytes EEPROM^
1K overlapped by register space
0x0800
0x1000
0x07FF
Mappable to any 2K Boundary
0x1000
12K Bytes RAM
See table below for mapping options
0x3FFF
0x4000
0x4000
0x7FFF
0.5K, 1K, 2K or 4K Protected Sector
16K Fixed Flash or ROM
0x8000
0x8000
16K Page Window
Sixteen * 16K Flash or ROM Pages
EXT
0xBFFF
0xC000
0xC000
16K Fixed Flash or ROM
0xFFFF
2K, 4K, 8K or 16K Protected Boot Sector
0xFF00
0xFF00
0xFFFF
VECTORS
VECTORS
VECTORS
NORMAL
SINGLE CHIP
EXPANDED*
SPECIAL
SINGLE CHIP
0xFFFF
BDM
(If Active)
* Assuming that a ‘0’ was driven onto port K7 during reset to normal expanded mode
^ EEPROM is not available in ROM device
Figure 1-2. MC9(3)S12HZ256 Memory Map
Table 1-2. MC9(3)S12HZ256 RAM mapping options
INITRM
RAM location
0x00
0x0000 - 0x2FFF
0x39
0x1000 - 0x3FFF
0x40
0x4000 - 0x6FFF
0x79
0x5000 - 0x7FFF
0x80
0x8000 - 0xAFFF
0xB9
0x9000 - 0xBFFF
0xC0
0xC000 - 0xEFFF
0xF9
0xD000 - 0xFFFF
MC9S12HZ256 Data Sheet, Rev. 2.04
26
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-3 shows the device memory map for the MC9(3)S12HZ128 out of reset.
0x0000
0x0400
0x0000
1K Register Space
0x03FF
Mappable to any 2K Boundary
0x0000
2K Bytes EEPROM^
1K overlapped by register space
0x0800
0x2800
0x07FF
Mappable to any 2K Boundary
0x2800
6K Bytes RAM
See table below for mapping options
0x3FFF
0x4000
0x4000
0x7FFF
0.5K, 1K, 2K or 4K Protected Sector
16K Fixed Flash or ROM
0x8000
0x8000
16K Page Window
Eight * 16K Flash or ROM Pages
EXT
0xBFFF
0xC000
0xC000
16K Fixed Flash or ROM
0xFFFF
2K, 4K, 8K or 16K Protected Boot Sector
0xFF00
0xFF00
0xFFFF
VECTORS
VECTORS
VECTORS
NORMAL
SINGLE CHIP
EXPANDED*
SPECIAL
SINGLE CHIP
0xFFFF
BDM
(If Active)
* Assuming that a ‘0’ was driven onto port K7 during reset to normal expanded mode
^ EEPROM is not available in ROM device
Figure 1-3. MC9(3)S12HZ128 Memory Map
Table 1-3. MC9(3)S12HZ128 RAM mapping options
1
Reserved location
INITRM1
RAM location
0x00
0x0000 - 0x17FF
0x1800 - 0x2FFF
0x39
0x2800 - 0x3FFF
0x1000 - 0x27FF
0x40
0x4000 - 0x57FF
0x5800 - 0x6FFF
0x79
0x6800 - 0x7FFF
0x5000 - 0x67FF
0x80
0x8000 - 0x97FF
0x9800 - 0xAFFF
0xB9
0xA800 - 0xBFFF
0x9000 - 0xA7FF
0xC0
0xC000 - 0xD7FF
0xD800 - 0xEFFF
0xF9
0xE800 - 0xFFFF
0xD000 - 0xE7FF
(no Flash/ROM/EEPROM access)
User must initialize RAM13 bit to the same value as RAMHAL bit
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
27
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-4 shows the device memory map for the MC9(3)S12HZ64 and MC9(3)S12HN64 out of reset.
0x0000
0x0400
0x0000
1K Register Space
0x03FF
Mappable to any 2K Boundary
1K Bytes EEPROM^
1K overlapped by register space
Mappable to any 2K Boundary
(1K mapped twice in 2K space)
4K Bytes RAM
See table below for mapping options
0x0000
0x0800
0x07FF
0x3000
0x3000
0x3FFF
0x4000
0x4000
0x7FFF
0.5K, 1K, 2K or 4K Protected Sector
16K Fixed Flash or ROM
0x8000
0x8000
16K Page Window
Four * 16K Flash or ROM Pages
0xBFFF
0xC000
0xC000
16K Fixed Flash or ROM
0xFFFF
2K, 4K, 8K or 16K Protected Boot Sector
0xFF00
0xFF00
0xFFFF
VECTORS
VECTORS
NORMAL
SINGLE CHIP
SPECIAL
SINGLE CHIP
0xFFFF
BDM
(If Active)
^ EEPROM is not available in ROM devices
Figure 1-4. MC9(3)S12HZ64 and M9S12(3)HN64 Memory Map
Table 1-4. MC9(3)S12HZ64 and M9S12(3)HN64 RAM mapping options
1
Reserved location
INITRM1
RAM location
0x00
0x0000 - 0x0FFF
0x1000 - 0x2FFF
0x39
0x3000 - 0x3FFF
0x1000 - 0x2FFF
0x40
0x4000 - 0x4FFF
0x5000 - 0x6FFF
0x79
0x7000 - 0x7FFF
0x5000 - 0x6FFF
0x80
0x8000 - 0x8FFF
0x9000 - 0xAFFF
0xB9
0xB000 - 0xBFFF
0x9000 - 0xAFFF
0xC0
0xC000 - 0xCFFF
0xD000 - 0xEFFF
0xF9
0xF000 - 0xFFFF
0xD000 - 0xEFFF
(no Flash/ROM/EEPROM access)
User must initialize RAM13 and RAM12 bits to the same value as RAMHAL bit
MC9S12HZ256 Data Sheet, Rev. 2.04
28
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-5 shows the device memory map for the MC3S12HZ32 and MC93S12HN32 out of reset.
0x0000
0x0400
0x0000
1K Register Space
0x03FF
Mappable to any 2K Boundary
0x3800
2K Bytes RAM
See table below for mapping options
0x0800
0x3800
0x3FFF
0x4000
0x4000
0x7FFF
0.5K, 1K, 2K or 4K Protected Sector
16K Fixed ROM
0x8000
0x8000
16K Page Window
Two * 16K ROM Pages
0xBFFF
0xC000
0xC000
16K Fixed ROM
0xFFFF
2K, 4K, 8K or 16K Protected Boot Sector
0xFF00
0xFF00
0xFFFF
VECTORS
VECTORS
NORMAL
SINGLE CHIP
SPECIAL
SINGLE CHIP
0xFFFF
BDM
(If Active)
Figure 1-5. MC3S12HZ32 and MC3S12HN32 Memory Map
Table 1-5. MC3S12HZ32 and MC3S12HN32 RAM mapping options
1
INITRM1
RAM location
Reserved location
0x00
0x0000 - 0x07FF
0x0800 - 0x2FFF
0x39
0x3800 - 0x3FFF
0x1000 - 0x37FF
0x40
0x4000 - 0x47FF
0x4800 - 0x6FFF
0x79
0x7800 - 0x7FFF
0x5000 - 0x77FF
0x80
0x8000 - 0x87FF
0x8800 - 0xAFFF
0xB9
0xB800 - 0xBFFF
0x9000 - 0xB7FF
0xC0
0xC000 - 0xC7FF
0xC800 - 0xEFFF
0xF9
0xF800 - 0xFFFF
0xD000 - 0xF7FF
(no ROM access)
User must initialize RAM13, RAM12 and RAM11 bits to the same value as RAMHAL bit
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
29
Chapter 1 MC9S12HZ256 Device Overview
1.3
Part ID Assignments and Mask Set Numbers
The part ID is located in two 8-bit registers PARTIDH and PARTIDL at addresses 0x001A and 0X001B,
respectively. The rado-only value is a unique part ID for each revision of the chip. Table 1-6 shows the
assigned part ID and Mask Set numbers.
Table 1-6. Assigned Part ID and Mask Set Numbers
1
Part Names
Mask Set
Part ID
MC9S12HZ256
MC9S12HZ128
MC9S12HZ64
MC9S12HN64
MC3S12HZ256
MC3S12HZ128
2L16Y/3L16Y
0x1402/0x1403
MC3S12HZ64
MC3S12HN64
MC3S12HZ32
MC3S12HN32
1M36C
0x1501
1 The coding is as follows:
Bit 15-12: Major family identifier
Bit 11-8: Minor family identifier
Bit 7-4: Major mask set revision including fab transfers
Bit 3-0: Minor non-full mask set revision
The device memory sizes are located in two 8-bit registers MEMSIZ0 and MEMZI1 (addresses 0x001C
and 0x001D after reset). Table 1-7 shows the read-only values of these registers. Refer to the HCS12 MMC
block description chapter for further details.
Table 1-7. Memory Size Registers
Part Names
MEMSIZ0
MEMSIZ1
MC9S12HZ256
MC9S12HZ128
MC9S12HZ64
MC9S12HN64
MC3S12HZ256
MC3S12HZ128
0x15
0x81
MC3S12HZ64
MC3S12HN64
MC3S12HZ32
MC3S12HN32
0x01
0x80
MC9S12HZ256 Data Sheet, Rev. 2.04
30
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.4
Signal Description
This section describes signals that connect off-chip. It includes a pinout diagram, a table of signal
properties, and detailed discussion of signals. It is built from the signal description sections of the block
description chapters of the individual IP blocks on the device.
1.4.1
Device Pinout
The MC9S12HZ256 are available in a 112-pin quad flat pack (LQFP) and a 80-pin quad flat pack (QFP).
Most pins perform two or more functions, as described in 1.5, “Detailed Signal Descriptions”. Figure 1-6,
Figure 1-7 and Figure 1-8 show the pin assignments.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
31
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MC9S12HZ256,
MC9S12HZ128,
MC3S12HZ256,
MC3S12HZ128
112 LQFP
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
PB5/ADDR5/DATA5/FP5
PB4/ADDR4/DATA4/FP4
PB3/ADDR3/DATA3/FP3
PB2/ADDR2/DATA2/FP2
PB1/ADDR1/DATA1/FP1
PB0/ADDR0/DATA0/FP0
PK0/XADDR14/BP0
PK1/XADDR15/BP1
PK2/XADDR16/BP2
PK3/XADDR17/BP3
VLCD
VSS1
VDD1
PAD7/KWAD7/AN7
PAD6/KWAD6/AN6
PAD5/KWAD5/AN5
PAD4/KWAD4/AN4
PAD3/KWAD3/AN3
PAD2/KWAD2/AN2
PAD1/KWAD1/AN1
PAD0/KWAD0/AN0
VDDA
VRH
VRL
VSSA
PE0/XIRQ
PE4/ECLK
PE6/IPIPE1/MODB
PWM3/PP3
RXD1/PWM2/PP2
TXD1/PWM0/PP0
PWM1/PP1
RXD0/PS0
TXD0/PS1
VSS2
VDDR
VDDX2
VSSX2
MODC/TAGHI/BKGD
RESET
VDDPLL
XFC
VSSPLL
EXTAL
XTAL
TEST
RXCAN0/PM2
TXCAN0/PM3
RXCAN1/PM4
TXCAN1/PM5
MODA/IPIP0/PE5
MISO/PS4
MOSI/PS5
SCK/PS6
SS/PS7
IRQ/PE1
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
FP28/AN12/PL4
FP29/AN13/PL5
FP30/AN14/PL6
FP31/AN15/PL7
VDDM1
VSSM1
M0C0M/M0COSM/PU0
M0C0P/M0COSP/PU1
M0C1M/M0SINM/PU2
M0C1P/M0SINP/PU3
M1C0M/M1COSM/PU4
M1C0P/M1COSP/PU5
M1C1M/M1SINM/PU6
M1C1P/M1SINP/PU7
VDDM2
VSSM2
M2C0M/M2COSM/PV0
M2C0P/M2COSP/PV1
M2C1M/M2SINM/PV2
M2C1P/M2SINP/PV3
M3C0M/M3COSM/PV4
M3C0P/M3COSP/PV5
M3C1M/M3SINM/PV6
M3C1P/M3SINP/PV7
VDDM3
VSSM3
SCL/PWM5/PP5
SDA/PWM4/PP4
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
PT7/IOC7
PT6/IOC6
PT5/IOC5
PT4/IOC4
PT3/IOC3/FP27
PT2/IOC2/FP26
PT1/IOC1/FP25
PT0/IOC0/FP24
VSSX1
VDDX1
PK7/ECS/ROMCTL/FP23
PE7/NOACC/XCLKS/FP22
PE3/LSTRB/TAGLO/FP21
PE2/R/W/FP20
PL3/AN11/FP19
PL2/AN10/FP18
PL1/AN9/FP17
PL0/AN8/FP16
PA7/ADDR15/DATA15/FP15
PA6/ADDR14/DATA14/FP14
PA5/ADDR13/DATA13/FP13
PA4/ADDR12/DATA12/FP12
PA3/ADDR11/DATA11/FP11
PA2/ADDR10/DATA10/FP10
PA1/ADDR9/DATA9/FP9
PA0/ADDR8/DATA8/FP8
PB7/ADDR7/DATA7/FP7
PB6/ADDR6/DATA6/FP6
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-6. 112-Pin LQFP for MC9S12HZ256, MC9S12HZ128, MC3S12HZ256 and MC3S12HZ128
MC9S12HZ256 Data Sheet, Rev. 2.04
32
Freescale Semiconductor
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
MC9S12HZ64,
MC9S12HN64,
MC3S12HZ64,
MC3S12HN64
112 LQFP
Signals shown in BOLD are not available in the 80 QFP package
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
PB5/FP5
PB4/FP4
NC
NC
NC
NC
PK0/BP0
PK1/BP1
PK2/BP2
PK3/BP3
VLCD
VSS1
VDD1
PAD7/KWAD7/AN7
PAD6/KWAD6/AN6
PAD5/KWAD5/AN5
PAD4/KWAD4/AN4
PAD3/KWAD3/AN3
PAD2/KWAD2/AN2
PAD1/KWAD1/AN1
PAD0/KWAD0/AN0
VDDA/VRH
NC
NC
VSSA/VRL
PE0/XIRQ
PE4/ECLK
NC
PWM3/PP3
NC
NC
PWM1/PP1
RXD0/PS0
TXD0/PS1
VSS2
VDDR
VDDX2
VSSX2
MODC/BKGD
RESET
VDDPLL
XFC
VSSPLL
EXTAL
XTAL
TEST
RXCAN0/PM2
TXCAN0/PM3
NC
NC
NC
MISO/PS4
MOSI/PS5
SCK/PS6
NC
NC
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
NC
NC
NC
NC
NC
NC
M0C0M/M0COSM/PU0
M0C0P/M0COSP/PU1
M0C1M/M0SINM/PU2
M0C1P/M0SINP/PU3
M1C0M/M1COSM/PU4
M1C0P/M1COSP/PU5
M1C1M/M1SINM/PU6
M1C1P/M1SINP/PU7
VDDM2
VSSM2
M2C0M/M0COSM/PV0
M2C0P/M0COSP/PV1
M2C1M/M0SINM/PV2
M2C1P/M0SINP/PV3
M3C0M/M1COSM/PV4
M3C0P/M1COSP/PV5
M3C1M/M1SINM/PV6
M3C1P/M1SINP/PV7
NC
NC
PWM5/PP5
PWM4/PP4
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
PT7/IOC7
PT6/IOC6
PT5/IOC5
PT4/IOC4
PT3/IOC3/FP27
PT2/IOC2/FP26
PT1/IOC1/FP25
PT0/IOC0/FP24
VSSX1
VDDX1
PK7/FP23
PE7/XCLKS/FP22
PE3/FP21
PE2/FP20
PL3/FP19
PL2/FP18
PL1/FP17
PL0/FP16
PA7/FP15
PA6/FP14
PA5/FP13
PA4/FP12
PA3/FP11
PA2/FP10
PA1/FP9
PA0/FP8
PB7/FP7
PB6/FP6
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-7. 112-Pin LQFP for MC9S12HZ(N)64 and MC3S12HZ(N)64
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
33
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
MC9S12HZ64,
MC9S12HN64,
MC3S12HZ64,
MC3S12HN64,
MC3S12HZ32,
MC3S12HN32
80 QFP
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
PB5/FP5
PB4/FP4
PK0/BP0
PK1/BP1
PK2/BP2
PK3/BP3
VLCD
VSS1
VDD1
PAD6/KWAD6/AN6
PAD5/KWAD5/AN5
PAD4/KWAD4/AN4
PAD3/KWAD3/AN3
PAD2/KWAD2/AN2
PAD1/KWAD1/AN1
PAD0/KWAD0/AN0
VDDA/VRH
VSSA/VRL
PE0/XIRQ
PE4/ECLK
PWM3/PP3
PWM1/PP1
RXD0/PS0
TXD0/PS1
VSS2
VDDR
VDDX2
VSSX2
MODC/BKGD
RESET
VDDPLL
XFC
VSSPLL
EXTAL
XTAL
TEST
RXCAN0/PM2
TXCAN0/PM3
PS4
PS6
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
M0C0M/M0COSM/PU0
M0C0P/M0COSP/PU1
M0C1M/M0SINM/PU2
M0C1P/M0SINP/PU3
M1C0M/M1COSM/PU4
M1C0P/M1COSP/PU5
M1C1M/M1SINM/PU6
M1C1P/M1SINP/PU7
VDDM2
VSSM2
M2C0M/M0COSM/PV0
M2C0P/M0COSP/PV1
M2C1M/M0SINM/PV2
M2C1P/M0SINP/PV3
M3C0M/M1COSM/PV4
M3C0P/M1COSP/PV5
M3C1M/M1SINM/PV6
M3C1P/M1SINP/PV7
PWM5/PP5
PWM4/PP4
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
PT3/IOC3/FP27
PT2/IOC2/FP26
PT1/IOC1/FP25
PT0/IOC0/FP24
VSSX1
VDDX1
PK7/FP23
PE7/XCLKS/FP22
PE3/FP21
PE2/FP20
PA7/FP15
PA6/FP14
PA5/FP13
PA4/FP12
PA3/FP11
PA2/FP10
PA1/FP9
PA0/FP8
PB7/FP7
PB6/FP6
Chapter 1 MC9S12HZ256 Device Overview
Figure 1-8. 80-Pin QFP for MC9S12HZ(N)64, MC3S12HZ(N)64 and MC3S12HZ(N)32
MC9S12HZ256 Data Sheet, Rev. 2.04
34
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.4.2
Signal Properties Summary
Table 1-8 summarizes all pin functions.
Table 1-8. Signal Properties
Pin
Name
Function 1
Pin
Name
Function 2
Pin
Name
Function 3
Pin
Name
Function 4
Powered
by
EXTAL
—
—
—
VDDPLL
Internal Pull Up
Resistor
Description
CTRL
Reset
State
NA
NA
Oscillator pins
XTAL
—
—
—
VDDPLL
NA
NA
RESET
—
—
—
VDDX2
None
None
TEST
—
—
—
VDDX2
NA
NA
Test input - must be tied to
VSS in all applications
XFC
—
—
—
VDDPLL
NA
NA
PLL loop Filter
BKGD
TAGHI
MODC
—
VDDX2
Always
Up
Up
Background debug, tag high,
mode pin
PAD[7:0]
AN[7:0]
KWAD[7:0]
—
VDDA
PERAD/
PPSAD
PA[7:0]
FP[15:8]
ADDR[15:8]/
DATA[15:8]
—
VDDX1
PUCR
Down
Port A I/O, multiplexed
address/data
PB[7:0]
FP[7:0]
ADDR[7:0]/
DATA[7:0]
—
VDDX1
PUCR
Down
Port B I/O, multiplexed
address/data
PE7
FP22
XCLKS
NOACC
VDDX1
PUCR
Down
Port E I/O, access, clock
select, LCD driver
PE6
IPIPE1
MODB
—
VDDX2
While RESET
pin is low: Down
Port E I/O, pipe status, mode
input
PE5
IPIPE0
MODA
—
VDDX2
While RESET
pin is low: Down
Port E I/O, pipe status, mode
input
PE4
ECLK
—
—
VDDX2
PUCR
Down
Port E I/O, bus clock output
PE3
FP21
LSTRB
TAGLO
VDDX1
PUCR
Down
Port E I/O, LCD driver, byte
strobe, tag low
PE2
FP20
R/W
—
VDDX1
PUCR
Down
Port E I/O, R/W in expanded
modes
PE1
IRQ
—
—
VDDX2
PUCR
PE0
XIRQ
—
—
VDDX2
PK7
FP23
ECS
ROMCTL
PK[3:0]
BP[3:0]
XADDR[17:14]
PL[7:4]
FP[31:28]
PL[3:0]
FP[19:16]
External reset pin
Disabled Port AD I/O, Analog inputs
(ATD), interrupts
Up
Port E input, maskable
interrupt
PUCR
Up
Port E input, non-maskable
interrupt
VDDX1
PUCR
Down
Port K I/O, emulation chip
select, ROM on enable
—
VDDX1
PUCR
Down
Port K I/O, LCD driver,
extended addresses
AN[15:12]
—
VDDA
PERL/
PPSL
Down
Port L I/O, LCD drivers, analog
inputs (ATD)
AN[11:8]
—
VDDX1
PERL/
PPSL
Down
Port L I/O, LCD drivers, analog
inputs (ATD)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
35
Chapter 1 MC9S12HZ256 Device Overview
Table 1-8. Signal Properties (continued)
Internal Pull Up
Resistor
Pin
Name
Function 1
Pin
Name
Function 2
Pin
Name
Function 3
Pin
Name
Function 4
Powered
by
PM5
TXCAN1
—
—
VDDX2
PM4
RXCAN1
—
—
VDDX2
PM3
TXCAN0
—
—
VDDX2
Port M I/O, TX of CAN0
PM2
RXCAN0
—
—
VDDX2
Port M I/O, RX of CAN0
PP5
PWM5
SCL
—
VDDX2
PP4
PWM4
SDA
—
VDDX2
Port P I/O, PWM channel, SDA
of IIC
PP3
PWM3
—
—
VDDX2
Port P I/O, PWM channel
PP2
PWM2
RXD1
—
VDDX2
Port P I/O, PWM channel,
RXD of SCI1
PP1
PWM1
—
—
VDDX2
Port P I/O, PWM channel
PP0
PWM0
TXD1
—
VDDX2
Port P I/O, PWM channel, TXD
of SCI1
Description
CTRL
PERM/
PPSM
PERP/
PPSP
Reset
State
Disabled Port M I/O, TX of CAN1
Port M I/O, RX of CAN1
Disabled Port P I/O, PWM channel, SCL
of IIC
PS7
SS
—
—
VDDX2
PS6
SCK
—
—
VDDX2
PS5
MOSI
—
—
VDDX2
Port S I/O, MOSI of SPI
PS4
MISO
—
—
VDDX2
Port S I/O, MISO of SPI
PS1
TXD0
—
—
VDDX2
Port S I/O, TXD of SCI0
PS0
RXD0
—
—
VDDX2
PT[7:4]
IOC[7:4]
—
—
VDDX1
PT[3:0]
IOC[3:0]
FP[27:24]
—
VDDX1
PU7
M1C1P
M1SINP
—
VDDM1,2,3
PU6
M1C1M
M1SINM
—
VDDM1,2,3
PU5
M1C0P
M1COSP
—
VDDM1,2,3
PU4
M1C0M
M1COSM
—
VDDM1,2,3
PU3
M0C1P
M0SINP
—
VDDM1,2,3
PU2
M0C1M
M0SINM
—
VDDM1,2,3
PU1
M0C0P
M0COSP
—
VDDM1,2,3
PU0
M0C0M
M0COSM
—
VDDM1,2,3
PV7
M3C1P
M3SINP
M1SINP
VDDM1,2,3
PV6
M3C1M
M3SINM
M1SINM
VDDM1,2,3
PV5
M3C0P
M3COSP
M1COSP
VDDM1,2,3
PV4
M3C0M
M3COSM
M1COSM
VDDM1,2,3
PV3
M2C1P
M2SINP
M0SINP
VDDM1,2,3
PV2
M2C1M
M2SINM
M0SINM
VDDM1,2,3
PV1
M2C0P
M2COSP
M0COSP
VDDM1,2,3
PV0
M2C0M
M2COSM
M0COSM
VDDM1,2,3
PERS/
PPSS
Disabled Port S I/O, SS of SPI
Port S I/O, SCK of SPI
Port S I/O, RXD of SCI0
PERT/
PPST
PERU/
PPSU
Down
Port T I/O, Timer channels
Port T I/O, Timer channels,
LCD driver
Disabled Port U I/O, motor1 coil nodes
of MC or SSD1
Port U I/O, motor 0 coil nodes
of MC or SSD0
PERV/
PPSV
Disabled Port V I/O, motor 3 coil nodes
of MC or SSD3
Port V I/O, motor 2 coil nodes
of MC or SSD2
MC9S12HZ256 Data Sheet, Rev. 2.04
36
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
Table 1-9. Power and Ground
Mnemonic
Nominal
Voltage
VLCD
5.0 V
Voltage reference pin for the LCD driver.
VDD1
2.5 V
VSS1
VSS2
0V
Internal power and ground generated by internal regulator. These also allow an external source
to supply the core VDD/VSS voltages and bypass the internal voltage regulator.
VDDR
5.0 V
VSSR
0V
VDDX1
VDDX2
5.0 V
VSSX1
VSSX2
0V
VDDA
5.0 V
VSSA
0V
VRH
5.0 V
Reference voltage high for the ATD converter.
VRL
0V
Reference voltage low for the ATD converter.
VDDPLL
2.5 V
VSSPLL
0V
VDDM1,2,3
5.0 V
VSSM1,2,3
0V
Description
External power and ground, supply to pin drivers and internal voltage regulator.
External power and ground, supply to pin drivers.
Operating voltage and ground for the analog-to-digital converter and the reference for the internal
voltage regulator, allows the supply voltage to the A/D to be bypassed independently.
Provides operating voltage and ground for the phased-locked Loop. This allows the supply
voltage to the PLL to be bypassed independently. Internal power and ground generated by
internal regulator.
Provides operating voltage and ground for motor 0, 1, 2 and 3.
NOTE
All VSS pins must be connected together in the application. Because fast
signal transitions place high, short-duration current demands on the power
supply, use bypass capacitors with high-frequency characteristics and place
them as close to the MCU as possible. Bypass requirements depend on
MCU pin load.
1.5
1.5.1
Detailed Signal Descriptions
EXTAL, XTAL — Oscillator Pins
EXTAL and XTAL are the crystal driver and external clock pins. On reset all the device clocks are derived
from the EXTAL input frequency. XTAL is the crystal output.
1.5.2
RESET — External Reset Pin
An active low bidirectional control signal, it acts as an input to initialize the MCU to a known start-up
state, and an output when an internal MCU function causes a reset.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
37
Chapter 1 MC9S12HZ256 Device Overview
1.5.3
TEST — Test Pin
This pin is reserved for test.
NOTE
The TEST pin must be tied to VSS in all applications.
1.5.4
XFC — PLL Loop Filter Pin
Dedicated pin used to create the PLL loop filter. Please ask your Freescale representative for the
interactive application note to compute PLL loop filter elements. Any current leakage on this pin must be
avoided.
XFC
R
MCU
CP
CS
VDDPLL
VDDPLL
Figure 1-9. PLL Loop Filter Connections
1.5.5
BKGD / TAGHI / MODC — Background Debug, Tag High, and Mode
Pin
The BKGD/TAGHI/MODC pin is used as a pseudo-open-drain pin for the background debug
communication. In MCU expanded modes of operation when instruction tagging is on, an input low on
this pin during the falling edge of E-clock tags the high half of the instruction word being read into the
instruction queue. It is used as a MCU operating mode select pin during reset. The state of this pin is
latched to the MODC bit at the rising edge of RESET.
1.5.6
1.5.6.1
Port Pins
PAD[7:0] / AN[7:0] / KWAD[7:0] — Port AD I/O Pins [7:0]
PAD7–PAD0 are general-purpose input or output pins and analog inputs for the analog-to-digital
converter. They can be configured to generate an interrupt causing the MCU to exit STOP or WAIT mode.
1.5.6.2
PA[7:0] / FP[15:8] / ADDR[15:8] / DATA[15:8] — Port A I/O Pins
PA7–PA0 are general-purpose input or output pins. They can be configured as frontplane segment driver
outputs FP15–FP8 of the LCD. In MCU expanded modes of operation, these pins are used for the
multiplexed external address and data bus.
MC9S12HZ256 Data Sheet, Rev. 2.04
38
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.5.6.3
PB[7:0] / FP[7:0] / ADDR[7:0] / DATA[7:0] — Port B I/O Pins
PB7–PB0 are general-purpose input or output pins. They can be configured as frontplane segment driver
outputs FP7–FP0 of the LCD. In MCU expanded modes of operation, these pins are used for the
multiplexed external address and data bus.
1.5.6.4
PE7 / FP22 / XCLKS / NOACC — Port E I/O Pin 7
PE7 is a general-purpose input or output pin. It can be configured as frontplane segment driver output FP22
of the LCD module.
The XCLKS is an input signal which controls whether a crystal in combination with the internal Colpitts
(low power) oscillator is used or whether Pierce oscillator/external clock circuitry is used. The state of this
pin is latched at the rising edge of RESET. If the input is a logic high the EXTAL pin is configured for an
external clock drive or a Pierce Oscillator. If the input is a logic low a Colpitts oscillator circuit is
configured on EXTAL and XTAL. Because this pin is an input with a pull-down device during reset, if the
pin remains floating, the default configuration is a Colpitts oscillator circuit on EXTAL and XTAL.
EXTAL
CDC*
C1
MCU
Crystal or
ceramic resonator
XTAL
C2
VSSPLL
* Due to the nature of a translated ground Colpitts oscillator a
DC voltage bias is applied to the crystal. Please contact
the crystal manufacturer for crystal DC.
Figure 1-10. Colpitts Oscillator Connections (PE7 = 0)
EXTAL
C1
MCU
XTAL
RB
RS*
Crystal or
ceramic resonator
C2
VSSPLL
* Rs can be zero (shorted) when use with higher frequency crystals.
Refer to manufacturer’s data.
Figure 1-11. Pierce Oscillator Connections (PE7 = 1)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
39
Chapter 1 MC9S12HZ256 Device Overview
1.5.6.5
PE6 / MODB / IPIPE1 — Port E I/O Pin 6
PE6 is a general-purpose input or output pin. It is used as a MCU operating mode select pin during reset.
The state of this pin is latched to the MODB bit at the rising edge of RESET. This pin is shared with the
instruction queue tracking signal IPIPE1. This pin is an input with a pull-down device which is only active
when RESET is low.
1.5.6.6
PE5 / MODA / IPIPE0 — Port E I/O Pin 5
PE5 is a general-purpose input or output pin. It is used as a MCU operating mode select pin during reset.
The state of this pin is latched to the MODA bit at the rising edge of RESET. This pin is shared with the
instruction queue tracking signal IPIPE0. This pin is an input with a pull-down device which is only active
when RESET is low.
1.5.6.7
PE4 / ECLK — Port E I/O Pin 4
PE4 is a general-purpose input or output pin. It can be configured to drive the internal bus clock ECLK.
ECLK can be used as a timing reference.
1.5.6.8
PE3 / FP21 / LSTRB / TAGLO — Port E I/O Pin 3
PE3 is a general-purpose input or output pin. It can be configured as frontplane segment driver output FP21
of the LCD module. In MCU expanded modes of operation, LSTRB is used for the low-byte strobe
function to indicate the type of bus access and when instruction tagging is on, TAGLO is used to tag the
low half of the instruction word being read into the instruction queue.
1.5.6.9
PE2 / FP20 / R/W — Port E I/O Pin 2
PE2 is a general-purpose input or output pin. It can be configured as frontplane segment driver output FP20
of the LCD module. In MCU expanded modes of operations, this pin performs the read/write output signal
for the external bus. It indicates the direction of data on the external bus.
1.5.6.10
PE1 / IRQ — Port E Input Pin 1
PE1 is a general-purpose input pin and also the maskable interrupt request input that provides a means of
applying asynchronous interrupt requests. If IRQ is enabled, this pin can wake up the MCU from stop or
wait mode.
1.5.6.11
PE0 / XIRQ — Port E Input Pin 0
PE0 is a general-purpose input pin and also the non-maskable interrupt request input that provides a means
of applying asynchronous interrupt requests. This can wake up the MCU from stop or wait mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
40
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.5.6.12
PK7 / FP23 / ECS / ROMCTL — Port K I/O Pin 7
PK7 is a general-purpose input or output pin. It can be configured as frontplane segment driver output
FP23 of the LCD module.
During MCU expanded modes of operation, this pin is used as the emulation chip select output (ECS).
During MCU expanded modes of operation, this pin is used to enable the Flash EEPROM memory in the
memory map (ROMCTL). At the rising edge of RESET, the state of this pin is latched to the ROMON bit.
For all other modes the reset state of the ROMON bit is as follows:
Special single: ROMCTL = 1
Normal single: ROMCTL = 1
Emulation expanded wide: ROMCTL = 0
Emulation expanded narrow: ROMCTL = 0
Special test: ROMCTL = 0
Peripheral test: ROMCTL = 1
1.5.6.13
PK[3:0] / BP[3:0] / XADDR[17:14] — Port K I/O Pins [3:0]
PK3–PK0 are general-purpose input or output pins. They can be configured as backplane segment driver
outputs BP3–BP0 of the LCD module. In MCU expanded modes of operation, these pins provide the
expanded address XADDR[17:14] for the external bus.
1.5.6.14
PL[7:4] / FP[31:28] / AN[15:12] — Port L I/O Pins [7:4]
PL7–PL4 are general-purpose input or output pins. They can be configured as frontplane segment driver
outputs FP31–FP28 of the LCD module or analog inputs for the analog-to-digital converter.
1.5.6.15
PL[3:0] / FP[19:16] / AN[11:8] — Port L I/O Pins [3:0]
PL3–PL0 are general-purpose input or output pins. They can be configured as frontplane segment driver
outputs FP19–FP16 of the LCD module or analog inputs for the analog-to-digital converter.
1.5.6.16
PM5 / TXCAN1 — Port M I/O Pin 5
PM5 is a general-purpose input or output pin. It can be configured as the transmit pin TXCAN1 of the
scalable controller area network controller 1 (CAN1)
1.5.6.17
PM4 / RXCAN1 — Port M I/O Pin 4
PM4 is a general-purpose input or output pin. It can be configured as the receive pin RXCAN1 of the
scalable controller area network controller 1 (CAN1)
1.5.6.18
PM3 / TXCAN0 — Port M I/O Pin 3
PM3 is a general-purpose input or output pin. It can be configured as the transmit pin TXCAN0 of the
scalable controller area network controller 0 (CAN0)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
41
Chapter 1 MC9S12HZ256 Device Overview
1.5.6.19
PM2 / RXCAN0 — Port M I/O Pin 2
PM2 is a general-purpose input or output pin. It can be configured as the receive pin RXCAN0 of the
scalable controller area network controller 0 (CAN0)
1.5.6.20
PP5 / PWM5 — Port P I/O Pin 5
PP5 is a general-purpose input or output pin. It can be configured as pulse width modulator (PWM)
channel output PWM5 or the serial clock pin SCL of the inter-IC bus interface (IIC).
1.5.6.21
PP4 / PWM4 — Port P I/O Pin 4
PP4 is a general-purpose input or output pin. It can be configured as pulse width modulator (PWM)
channel output PWM4 or the serial data pin SDA of the inter-IC bus interface (IIC).
1.5.6.22
PP3 / PWM3 — Port P I/O Pin 3
PP3 is a general-purpose input or output pin. It can be configured as pulse width modulator (PWM)
channel output PWM3.
1.5.6.23
PP2 / PWM2 — Port P I/O Pin 2
PP2 is a general-purpose input or output pin. It can be configured as pulse width modulator (PWM)
channel output PWM2 or the receive pin RXD1 of the serial communication interface 1 (SCI1).
1.5.6.24
PP1 / PWM1 — Port P I/O Pin 1
PP1 is a general-purpose input or output pin. It can be configured as pulse width modulator (PWM)
channel output PWM1.
1.5.6.25
PP0 / PWM0 — Port P I/O Pin 0
PP0 is a general-purpose input or output pin. It can be configured as pulse width modulator (PWM)
channel output PWM0 or the transmit pin TXD1 of the serial communication interface 1 (SCI1).
1.5.6.26
PS7 / SS — Port S I/O Pin 7
PS7 is a general-purpose input or output pin. It can be configured as slave select pin SS of the serial
peripheral interface (SPI).
1.5.6.27
PS6 / SCK — Port S I/O Pin 6
PS6 is a general-purpose input or output pin. It can be configured as serial clock pin SCK of the serial
peripheral interface (SPI).
MC9S12HZ256 Data Sheet, Rev. 2.04
42
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.5.6.28
PS5 / MOSI — Port S I/O Pin 5
PS5 is a general-purpose input or output pin. It can be configured as the master output (during master
mode) or slave input (during slave mode) pin MOSI of the serial peripheral interface (SPI).
1.5.6.29
PS4 / MISO — Port S I/O Pin 4
PS4 is a general-purpose input or output pin. It can be configured as master input (during master mode) or
slave output (during slave mode) pin MISO for the serial peripheral interface (SPI).
1.5.6.30
PS1 / TXD0 — Port S I/O Pin 1
PS1 is a general-purpose input or output pin. It can be configured as transmit pin TXD0 of the serial
communication interface 0 (SCI0).
1.5.6.31
PS0 / RXD0 — Port S I/O Pin 0
PS0 is a general-purpose input or output pin. It can be configured as receive pin RXD0 of the serial
communication interface 0 (SCI0).
1.5.6.32
PT[7:4] / IOC[7:4] — Port T I/O Pins [7:4]
PT7–PT4 are general-purpose input or output pins. They can be configured as input capture or output
compare pins IOC7–IOC4 of the timer (TIM).
1.5.6.33
PT[3:0] / IOC[3:0] / FP[27:24] — Port T I/O Pins [3:0]
PT3–PT0 are general-purpose input or output pins. They can be configured as input capture or output
compare pins IOC3–IOC0 of the timer (TIM). They can be configured as frontplane segment driver
outputs FP27–FP24 of the LCD module.
1.5.6.34
PU[7:4] / M1C1(SIN)P, M1C1(SIN)M, M1C0(COS)P, M1C0(COS)M — Port U
I/O Pins [7:4]
PU7–PU4 are general-purpose input or output pins. They can be configured as high current PWM output
pins which can be used for motor drive or to measure the back EMF to calibrate the pointer reset position.
These pins interface to the coils of motor 1.
1.5.6.35
PU[3:0] / M0C1(SIN)P, M0C1(SIN)M, M0C0(COS)P, M0C0(COS)M — Port U
I/O Pins [3:0]
PU3–PU0 are general-purpose input or output pins. They can be configured as high current PWM output
pins which can be used for motor drive or to measure the back EMF to calibrate the pointer reset position.
These pins interface to the coils of motor 0.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
43
Chapter 1 MC9S12HZ256 Device Overview
1.5.6.36
PV[7:4] / M3C1(SIN)P, M3C1(SIN)M, M3C0(COS)P, M3C0(COS)M — Port V
I/O Pins [7:4]
PV7–PV4 are general-purpose input or output pins. They can be configured as high current PWM output
pins which can be used for motor drive or to measure the back EMF to calibrate the pointer reset position.
These pins interface to the coils of motor 3.
1.5.6.37
PV[3:0] / M2C1(SIN)P, M2C1(SIN)M, M2C0(COS)P, M2C0(COS)M — Port V
I/O Pins [3:0]
PV3–PV0 are general-purpose input or output pins. They can be configured as high current PWM output
pins which can be used for motor drive or to measure the back EMF to calibrate the pointer reset position.
These pins interface to the coils of motor 2.
1.5.7
Power Supply Pins
MC9S12HZ256 power and ground pins are described below.
NOTE
All VSS pins must be connected together in the application (See
Appendix B, “PCB Layout Guidelines”).
Because fast signal transitions place high, short-duration current demands
on the power supply, use bypass capacitors with high-frequency
characteristics and place them as close to the MCU as possible. Bypass
requirements depend on how heavily the MCU pins are loaded (Table B-1).
1.5.7.1
VDDR — External Power Pin
VDDR is the power supply pin for the internal voltage regulator.
1.5.7.2
VDDX1, VDDX2, VSSX1, VSSX2 — External Power and Ground Pins
VDDX1, VDDX2, VSSX1 and VSSX2 are the power supply and ground pins for input/output drivers.VDDX1
and VDDX2 as well as VSSX1 and VSSX2 are not internally connected.
1.5.7.3
VDD1, VSS1, VSS2 — Internal Logic Power Pins
VDD1, VSS1 and VSS2 are the internal logic power and ground pins and related to the voltage regulator
output. These pins serve as connection points for filter capacitors. VSS1 and VSS2 are internally connected.
NOTE
No load allowed except for bypass capacitors.
1.5.7.4
VDDA, VSSA — Power Supply Pins for ATD and VREG
VDDA, VSSA are the power supply and ground pins for the voltage regulator and the analog-to-digital
converter.
MC9S12HZ256 Data Sheet, Rev. 2.04
44
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.5.7.5
VDDM1, VDDM2, VDDM3 — Power Supply Pins for Motor 0 to 3
VDDM1, VDDM2 and VDDM3 are the supply pins for the ports U and V. VDDM1, VDDM2 and VDDM3 are
internally connected.
1.5.7.6
VSSM1, VSSM2, VSSM3 — Ground Pins for Motor 0 to 3
VSSM1, VSSM2 and VSSM3 are the ground pins for the ports U and V. VSSM1, VSSM2 and VSSM3 are
internally connected.
1.5.7.7
VLCD — Power Supply Reference Pin for LCD driver
VLCD is the voltage reference pin for the LCD driver. Adjusting the voltage on this pin will change the
display contrast.
1.5.7.8
VRH, VRL — ATD Reference Voltage Input Pins
VRH and VRL are the voltage reference pins for the analog-to-digital converter.
1.5.7.9
VDDPLL, VSSPLL — Power Supply Pins for PLL
VDDPLL and VSSPLL are the PLL supply pins and serve as connection points for external loop filter
components.
NOTE
No load allowed except for bypass capacitors.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
45
Chapter 1 MC9S12HZ256 Device Overview
1.6
System Clock Description
The clock and reset generator (CRG) provides the internal clock signals for the core and all peripheral
modules. Figure 1-12 shows the clock connections from the CRG to all modules.
Consult the CRG block description chapter for details on clock generation.
HCS12 CORE
BDM
CPU
MEBI
MMC
INT
DBG
core clock
Flash
RAM
EEPROM
TIM
EXTAL
ATD
CRG
bus clock
PWM
SCI0, SCI1
oscillator clock
XTAL
SPI
CAN0, CAN1
IIC
MC
LCD
PIM
SSD1, SSD2,
SSD3, SSD4
Figure 1-12. Clock Connections
MC9S12HZ256 Data Sheet, Rev. 2.04
46
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.7
Modes of Operation
Eight possible modes determine the operating configuration of the MC9S12HZ256. Each mode has an
associated default memory map and external bus configuration.
Three low power modes exist for the device.
The operating mode out of reset is determined by the states of the MODC, MODB, and MODA pins during
reset (Table 1-10). The MODC, MODB, and MODA bits in the MODE register show the current operating
mode and provide limited mode switching during operation. The states of the MODC, MODB, and MODA
pins are latched into these bits on the rising edge of the reset signal.
Table 1-10. Mode Selection
MODC
MODB
MODA
Mode Description
0
0
0
Special Single Chip, BDM allowed and ACTIVE. BDM is allowed in all other modes
but a serial command is required to make BDM active.
0
0
1
Emulation Expanded Narrow, BDM allowed
X
1
0
Reserved for factory test
0
1
1
Emulation Expanded Wide, BDM allowed
1
0
0
Normal Single Chip, BDM allowed
1
0
1
Normal Expanded Narrow, BDM allowed
1
1
1
Normal Expanded Wide, BDM allowed
There are two basic types of operating modes:
1. Normal modes: Some registers and bits are protected against accidental changes.
2. Special modes: Allow greater access to protected control registers and bits for special purposes such
as testing.
A system development and debug feature, background debug mode (BDM), is available in all modes. In
special single-chip mode, BDM is active immediately after reset.
Some aspects of port E are not mode dependent. Bit 1 of port E is a general-purpose input or the IRQ
interrupt input. IRQ can be enabled by bits in the CPU’s condition codes register but it is inhibited at reset
so this pin is initially configured as a simple input with a pull-up. Bit 0 of port E is a general-purpose input
or the XIRQ interrupt input. XIRQ can be enabled by bits in the CPU’s condition codes register but it is
inhibited at reset so this pin is initially configured as a simple input with a pull-up. The ESTR bit in the
EBICTL register is set to one by reset in any user mode. This assures that the reset vector can be fetched
even if it is located in an external slow memory device. The PE6/MODB/IPIPE1 and PE5/MODA/IPIPE0
pins act as pull-down select inputs during reset and high-impedance select inputs after reset.
The following paragraphs discuss the default bus setup and describe which aspects of the bus can be
changed after reset on a per mode basis.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
47
Chapter 1 MC9S12HZ256 Device Overview
1.7.1
Normal Operating Modes
These modes provide three operating configurations. Background debug is available in all three modes,
but must first be enabled for some operations by means of a BDM background command, then activated.
1.7.1.1
Normal Single-Chip Mode
There is no external expansion bus in this mode. All pins of ports A, B, E and K are general-purpose I/O
pins initially configured with internal pull-downs enabled, except port E bits 1 and 0 which are available
as general-purpose input only pins with internal pull-ups enabled.
The pins associated with port E bits 6, 5, 3, and 2 cannot be configured for their alternate functions IPIPE1,
IPIPE0, LSTRB, and R/W while the MCU is in single chip modes. In single chip modes, the associated
control bits PIPOE, LSTRE, and RDWE are reset to zero. Writing the opposite state into them in single
chip mode does not change the operation of the associated port E pins.
In normal single chip mode, the MODE register is writable one time. This allows a user program to change
the bus mode to narrow or wide expanded mode and/or turn on visibility of internal accesses.
Port E, bit 4 can be configured for a free-running E clock output by clearing NECLK=0. Typically the only
use for an E clock output while the MCU is in single chip modes would be to get a constant speed clock
for use in the external application system.
1.7.1.2
Normal Expanded Wide Mode
All pins of ports A, B, E and K are general-purpose I/O pins initially configured with internal pull-downs
enabled, except port E bits 1 and 0 which are available as general-purpose input only pins with internal
pull-ups enabled.
In expanded wide modes, ports A and B are configured as a 16-bit multiplexed address and data bus and
port E bit 4 is configured as the E clock output signal. These signals allow external memory and peripheral
devices to be interfaced to the MCU.
Port E pins other than PE4/ECLK are configured as general-purpose I/O pins. Control bits PIPOE,
NECLK, LSTRE, and RDWE in the PEAR register can be used to configure port E pins to act as bus
control outputs instead of general-purpose I/O pins.
It is possible to enable the pipe status signals on port E bits 6 and 5 by setting the PIPOE bit in PEAR, but
it would be unusual to do so in this mode. Development systems where pipe status signals are monitored
would typically use the special variation of this mode.
The port E bit 2 pin can be reconfigured as the R/W bus control signal by writing “1” to the RDWE bit in
PEAR. If the expanded system includes external devices that can be written, such as RAM, the RDWE bit
would need to be set before any attempt to write to an external location. If there are no writable resources
in the external system, PE2 can remain a general-purpose I/O pin.
The port E bit 3 pin can be reconfigured as the LSTRB bus control signal by writing “1” to the LSTRE bit
in PEAR. The default condition of this pin is a general-purpose input because the LSTRB function is not
needed in all expanded wide applications.
MC9S12HZ256 Data Sheet, Rev. 2.04
48
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
The port E bit 4 pin is initially configured as ECLK output with stretch. The E clock output function
depends upon the settings of the NECLK bit in the PEAR register, the IVIS bit in the MODE register and
the ESTR bit in the EBICTL register. The E clock is available for use in external select decode logic or as
a constant speed clock for use in the external application system.
1.7.1.3
Normal Expanded Narrow Mode
This mode is used for lower cost production systems that use 8-bit wide external EPROMs or RAMs. Such
systems take extra bus cycles to access 16-bit locations but this may be preferred over the extra cost of
additional external memory devices.
Ports A and B are configured as a 16-bit address bus and port A is multiplexed with data. Internal visibility
is not available in this mode because the internal cycles would need to be split into two 8-bit cycles.
Because the PEAR register can only be written one time in this mode, use care to set all bits to the desired
states during the single allowed write.
The PE3/LSTRB pin is always a general-purpose I/O pin in normal expanded narrow mode. Although it
is possible to write the LSTRE bit in PEAR to “1” in this mode, the state of LSTRE is overridden and
port E bit 3 cannot be reconfigured as the LSTRB output.
It is possible to enable the pipe status signals on port E bits 6 and 5 by setting the PIPOE bit in PEAR, but
it would be unusual to do so in this mode. LSTRB would also be needed to fully understand system
activity. Development systems where pipe status signals are monitored would typically use special
expanded wide mode or occasionally special expanded narrow mode.
The PE4/ECLK pin is initially configured as ECLK output with stretch. The E clock output function
depends upon the settings of the NECLK bit in the PEAR register, the IVIS bit in the MODE register and
the ESTR bit in the EBICTL register. In normal expanded narrow mode, the E clock is available for use
in external select decode logic or as a constant speed clock for use in the external application system.
The PE2/R/W pin is initially configured as a general-purpose input with a pull-up but this pin can be
reconfigured as the R/W bus control signal by writing “1” to the RDWE bit in PEAR. If the expanded
narrow system includes external devices that can be written such as RAM, the RDWE bit would need to
be set before any attempt to write to an external location. If there are no writable resources in the external
system, PE2 can remain a general-purpose I/O pin.
1.7.1.4
Internal Visibility
Internal visibility is available when the MCU is operating in expanded wide modes or special narrow
mode. It is not available in single-chip, peripheral or normal expanded narrow modes. Internal visibility is
enabled by setting the IVIS bit in the MODE register.
If an internal access is made while E, R/W, and LSTRB are configured as bus control outputs and internal
visibility is off (IVIS = 0), E will remain low for the cycle, R/W will remain high, and address, data and
the LSTRB pins will remain at their previous state.
When internal visibility is enabled (IVIS = 1), certain internal cycles will be blocked from going external.
During cycles when the BDM is selected, R/W will remain high, data will maintain its previous state, and
address and LSTRB pins will be updated with the internal value. During CPU no access cycles when the
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
49
Chapter 1 MC9S12HZ256 Device Overview
BDM is not driving, R/W will remain high, and address, data and the LSTRB pins will remain at their
previous state.
1.7.1.5
Emulation Expanded Wide Mode
In expanded wide modes, ports A and B are configured as a 16-bit multiplexed address and data bus and
port E provides bus control and status signals. These signals allow external memory and peripheral devices
to be interfaced to the MCU. These signals can also be used by a logic analyzer to monitor the progress of
application programs.
The bus control related pins in port E (PE7/NOACC, PE6/MODB/IPIPE1, PE5/MODA/IPIPE0,
PE4/ECLK, PE3/LSTRB/TAGLO, and PE2/R/W) are all configured to serve their bus control output
functions rather than general-purpose I/O. Notice that writes to the bus control enable bits in the PEAR
register in special mode are restricted.
1.7.1.6
Emulation Expanded Narrow Mode
Expanded narrow modes are intended to allow connection of single 8-bit external memory devices for
lower cost systems that do not need the performance of a full 16-bit external data bus. Accesses to internal
resources that have been mapped external (i.e., PORTA, PORTB, DDRA, DDRB, PORTE, DDRE, PEAR,
PUCR, RDRIV) will be accessed with a 16-bit data bus on ports A and B. Accesses of 16-bit external
words to addresses which are normally mapped external will be broken into two separate 8-bit accesses
using port A as an 8-bit data bus. Internal operations continue to use full 16-bit data paths. They are only
visible externally as 16-bit information if IVIS = 1.
Ports A and B are configured as multiplexed address and data output ports. During external accesses,
address A15, data D15 and D7 are associated with PA7, address A0 is associated with PB0 and data D8
and D0 are associated with PA0. During internal visible accesses and accesses to internal resources that
have been mapped external, address A15 and data D15 is associated with PA7 and address A0 and data
D0 is associated with PB0.
The bus control related pins in port E (PE7/NOACC, PE6/MODB/IPIPE1, PE5/MODA/IPIPE0,
PE4/ECLK, PE3/LSTRB/TAGLO, and PE2/R/W) are all configured to serve their bus control output
functions rather than general-purpose I/O. Notice that writes to the bus control enable bits in the PEAR
register in special mode are restricted.
1.7.2
1.7.2.1
Special Operating Modes
Special Single-Chip Mode
When the MCU is reset in this mode, the background debug mode is enabled and active. The MCU does
not fetch the reset vector and execute application code as it would in other modes. Instead the active
background mode is in control of CPU execution and BDM firmware is waiting for additional serial
commands through the BKGD pin. When a serial command instructs the MCU to return to normal
execution, the system will be configured as described below unless the reset states of internal control
registers have been changed through background commands after the MCU was reset.
There is no external expansion bus after reset in this mode. Ports A and B are initially simple bidirectional
I/O pins that are configured as high-impedance inputs with internal pull-downs enabled; however, writing
MC9S12HZ256 Data Sheet, Rev. 2.04
50
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
to the mode select bits in the MODE register (which is allowed in special modes) can change this after
reset. All of the port E pins (except PE4/ECLK) are initially configured as general-purpose
high-impedance inputs with pull-downs enabled. PE4/ECLK is configured as the E clock output in this
mode.
The pins associated with port E bits 6, 5, 3, and 2 cannot be configured for their alternate functions IPIPE1,
IPIPE0, LSTRB, and R/W while the MCU is in single chip modes. In single chip modes, the associated
control bits PIPOE, LSTRE and RDWE are reset to zero. Writing the opposite value into these bits in
single chip mode does not change the operation of the associated port E pins.
Port E, bit 4 can be configured for a free-running E clock output by clearing NECLK = 0. Typically the
only use for an E clock output while the MCU is in single chip modes would be to get a constant speed
clock for use in the external application system.
1.8
Security
The device will make available a security feature preventing the unauthorized read and write of the
memory contents. This feature allows:
• Protection of the contents of FLASH
• Protection of the contents of EEPROM
• Operation in single-chip mode
• Operation from external memory with internal FLASH and EEPROM disabled
The user must be reminded that part of the security must lie with the user’s code. An extreme example
would be user’s code that dumps the contents of the internal program. This code would defeat the purpose
of security. At the same time the user may also wish to put a back door in the user’s program. An example
of this is the user downloads a key through the SCI which allows access to a programming routine that
updates parameters stored in EEPROM.
1.8.1
Securing the Microcontroller
After the user has programmed the FLASH and EEPROM (if desired), the part can be secured by
programming the security bits located in the FLASH module. These non-volatile bits will keep the part
secured through resetting the part and through powering down the part.
The security byte resides in a portion of the Flash array.
Check the Flash block description chapter for more details on the security configuration.
1.8.2
1.8.2.1
Operation of the Secured Microcontroller
Normal Single Chip Mode
This will be the most common usage of the secured part. Everything will appear the same as if the part was
not secured with the exception of BDM operation. The BDM operation will be blocked.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
51
Chapter 1 MC9S12HZ256 Device Overview
1.8.2.2
Executing from External Memory
The user may wish to execute from external space with a secured microcontroller. This is accomplished
by resetting directly into expanded mode. The internal FLASH and EEPROM will be disabled. BDM
operations will be blocked.
1.8.3
Unsecuring the Microcontroller
In order to unsecure the microcontroller, the internal FLASH and EEPROM must be erased. This can be
done through an external program in expanded mode.
After the user has erased the FLASH and EEPROM, the part can be reset into special single chip mode.
This invokes a program that verifies the erasure of the internal FLASH and EEPROM. After this program
completes, the user can erase and program the FLASH security bits to the unsecured state. This is generally
done through the BDM, but the user could also change to expanded mode (by writing the mode bits
through the BDM) and jumping to an external program (again through BDM commands). Note that if the
part goes through a reset before the security bits are reprogrammed to the unsecure state, the part will be
secured again.
1.9
Low Power Modes
Consult the respective block description chapter for information on the module behavior in stop, pseudo
stop, and wait mode.
1.10
Resets and Interrupts
Consult the Exception Processing section of the CPU12 Reference Manual for information on resets and
interrupts. Both local masking and CCR masking are included as listed in Table 1-11. System resets can
be generated through external control of the RESET pin, through the clock and reset generator module
CRG or through the low voltage reset (LVR) generator of the voltage regulator module. Refer to the CRG
and VREG block description chapters for detailed information on reset generation.
1.10.1
Vectors
Table 1-11 lists interrupt sources and vectors in default order of priority.
Table 1-11. Interrupt Vector Locations
CCR
Mask
Local Enable
HPRIO Value
to Elevate
None
None
—
Clock Monitor fail reset
None
COPCTL (CME, FCME)
—
COP failure reset
None
COP rate select
—
0xFFF8, 0xFFF9
Unimplemented instruction trap
None
None
—
0xFFF6, 0xFFF7
SWI
None
None
—
0xFFF4, 0xFFF5
XIRQ
X-Bit
None
—
Vector Address
Interrupt Source
0xFFFE, 0xFFFF
External Reset, Power On Reset or Low
Voltage Reset (see CRG Flags Register to
determine reset source)
0xFFFC, 0xFFFD
0xFFFA, 0xFFFB
MC9S12HZ256 Data Sheet, Rev. 2.04
52
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
Table 1-11. Interrupt Vector Locations (continued)
Vector Address
Interrupt Source
CCR
Mask
Local Enable
HPRIO Value
to Elevate
0xFFF2, 0xFFF3
IRQ
I-Bit
INTCR (IRQEN)
0xF2
0xFFF0, 0xFFF1
Real Time Interrupt
I-Bit
RTICTL (RTIE)
0xF0
0xFFEE, 0xFFEF
Timer channel 0
I-Bit
TIE (C0I)
0xEE
0xFFEC, 0xFFED
Timer channel 1
I-Bit
TIE (C1I)
0xEC
0xFFEA, 0xFFEB
Timer channel 2
I-Bit
TIE (C2I)
0xEA
0xFFE8, 0xFFE9
Timer channel 3
I-Bit
TIE (C3I)
0xE8
0xFFE6, 0xFFE7
Timer channel 4
I-Bit
TIE (C4I)
0xE6
0xFFE4, 0xFFE5
Timer channel 5
I-Bit
TIE (C5I)
0xE4
0xFFE2, 0xFFE3
Timer channel 6
I-Bit
TIE (C6I)
0xE2
0xFFE0, 0xFFE1
Timer channel 7
I-Bit
TIE (C7I)
0xE0
0xFFDE, 0xFFDF
Timer overflow
I-Bit
TSCR2 (TOI)
0xDE
0xFFDC, 0xFFDD
Pulse accumulator A overflow
I-Bit
PACTL (PAOVI)
0xDC
0xFFDA, 0xFFDB
Pulse accumulator input edge
I-Bit
PACTL (PAI)
0xDA
0xFFD8, 0xFFD9
SPI
I-Bit
SPCR1 (SPIE)
0xD8
0xFFD6, 0xFFD7
SCI0
I-Bit
SC0CR2
(TIE, TCIE, RIE, ILIE)
0xD6
0xFFD4, 0xFFD5
SCI1
I-Bit
SC1CR2
(TIE, TCIE, RIE, ILIE)
0xD4
0xFFD2, 0xFFD3
ATD
I-Bit
ATDCTL2 (ASCIE)
0xD2
0xFFD0, 0xFFD1
Reserved
I-Bit
Reserved
0xD0
0xFFCE, 0xFFCF
Reserved
I-Bit
Reserved
0xCE
0xFFCC, 0xFFCD
Reserved
I-Bit
Reserved
0xCC
0xFFCA, 0xFFCB
Reserved
I-Bit
Reserved
0xCA
0xFFC8, 0xFFC9
Port AD
I-Bit
PTADIF (PTADIE)
0xC8
0xFFC6, 0xFFC7
CRG PLL lock
I-Bit
CRGINT (LOCKIE)
0xC6
0xFFC4, 0xFFC5
CRG Self Clock Mode
I-Bit
CRGINT (SCMIE)
0xC4
0xFFC2, 0xFFC3
Reserved
I-Bit
Reserved
0xC2
0xFFC0, 0xFFC1
IIC Bus
I-Bit
IBCR (IBIE)
0xC0
0xFFBE, 0xFFBF
Reserved
I-Bit
Reserved
0xBE
0xFFBC, 0xFFBD
Reserved
I-Bit
Reserved
0xBC
0xFFBA, 0xFFBB
EEPROM
I-Bit
EECTL (CCIE, CBEIE)
0xBA
0xFFB8, 0xFFB9
FLASH
I-Bit
FCTL (CCIE, CBEIE)
0xB8
0xFFB6, 0xFFB7
CAN0 wake-up
I-Bit
CAN0RIER (WUPIE)
0xB6
0xFFB4, 0xFFB5
CAN0 errors
I-Bit
CAN0RIER (CSCIE, OVRIE)
0xB4
0xFFB2, 0xFFB3
CAN0 receive
I-Bit
CAN0RIER (RXFIE)
0xB2
0xFFB0, 0xFFB1
CAN0 transmit
I-Bit
CAN0TIER (TXEIE[2:0])
0xB0
0xFFAE, 0xFFAF
CAN1 wake-up
I-Bit
CAN1RIER (WUPIE)
0xAE
0xFFAC, 0xFFAD
CAN1 errors
I-Bit
CAN1RIER (CSCIE, OVRIE)
0xAC
0xFFAA, 0xFFAB
CAN1 receive
I-Bit
CAN1RIER (RXFIE)
0xAA
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
53
Chapter 1 MC9S12HZ256 Device Overview
Table 1-11. Interrupt Vector Locations (continued)
Vector Address
Interrupt Source
CCR
Mask
Local Enable
HPRIO Value
to Elevate
0xFFA8, 0xFFA9
CAN1 transmit
I-Bit
CAN1TIER (TXEIE[2:0])
0xA8
0xFFA6, 0xFFA7
Reserved
I-Bit
Reserved
0xA6
0xFFA4, 0xFFA5
Reserved
I-Bit
Reserved
0xA4
0xFFA2, 0xFFA3
Reserved
I-Bit
Reserved
0xA2
0xFFA0, 0xFFA1
SSD0
I-Bit
MDC0CTL (MCZIE, AOVIE)
0xA0
0xFF9E, 0xFF9F
SSD1
I-Bit
MDC1CTL (MCZIE, AOVIE)
0x9E
0xFF9C, 0xFF9D
SSD2
I-Bit
MDC2CTL (MCZIE, AOVIE)
0x9C
0xFF9A, 0xFF9B
SSD3
I-Bit
MDC3CTL (MCZIE, AOVIE)
0x9A
0xFF98, 0xFF99
Reserved
I-Bit
Reserved
0x98
0xFF96, 0xFF97
Motor Control Timer Overflow
I-Bit
MCCTL1 (MCOCIE)
0x96
0xFF94, 0xFF95
Reserved
I-Bit
Reserved
0x94
0xFF92, 0xFF93
Reserved
I-Bit
Reserved
0x92
0xFF90, 0xFF91
Reserved
I-Bit
Reserved
0x90
0xFF8E, 0xFF8F
Reserved
I-Bit
Reserved
0x8E
0xFF8C, 0xFF8D
PWM Emergency Shutdown
I-Bit
PWMSDN(PWMIE)
0x8C
0xFF8A, 0xFF8B
VREG Low Voltage Interrupt
I-Bit
VREGCTRL (LVIE)
0x8A
0xFF80–0xFF89
Reserved
I-Bit
Reserved
0x80–0x88
MC9S12HZ256 Data Sheet, Rev. 2.04
54
Freescale Semiconductor
Chapter 1 MC9S12HZ256 Device Overview
1.10.2
Resets
Resets are a subset of the interrupts featured in Table 1-12. The different sources capable of generating a
system reset are summarized in Table 1-12.
Table 1-12. Reset Summary
1.10.3
Reset
Priority
Source
Vector
Power-on Reset
1
CRG Module
0xFFFE, 0xFFFF
External Reset
1
RESET pin
0xFFFE, 0xFFFF
Low Voltage Reset
1
VREG Module
0xFFFE, 0xFFFF
Clock Monitor Reset
2
CRG Module
0xFFFC, 0xFFFD
COP Watchdog Reset
3
CRG Module
0xFFFA, 0xFFFB
Effects of Reset
When a reset occurs, MCU registers and control bits are changed to known start-up states. Refer to the
respective module block description chapters for register reset states. MC mode dependent pin
configuration of port A, B and E out of reset.
Refer to the PIM block description chapter for reset configurations of all peripheral module ports.
Refer to Table 1-1 for locations of the memories depending on the operating mode after reset.
The RAM array is not automatically initialized out of reset.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
55
Chapter 1 MC9S12HZ256 Device Overview
MC9S12HZ256 Data Sheet, Rev. 2.04
56
Freescale Semiconductor
Chapter 2
256 Kbyte Flash Module (FTS256K2V1)
2.1
Introduction
This document describes the FTS256K2 module that includes a 256 Kbyte Flash (nonvolatile) memory.
The Flash memory may be read as either bytes, aligned words, or misaligned words. Read access time is
one bus cycle for bytes and aligned words, and two bus cycles for misaligned words.
The Flash memory is ideal for program and data storage for single-supply applications allowing for field
reprogramming without requiring external voltage sources for program or erase. Program and erase
functions are controlled by a command driven interface. The Flash module supports both block erase and
sector erase. An erased bit reads 1 and a programmed bit reads 0. The high voltage required to program
and erase the Flash memory is generated internally. It is not possible to read from a Flash block while it is
being erased or programmed.
CAUTION
A Flash word must be in the erased state before being programmed.
Cumulative programming of bits within a Flash word is not allowed.
2.1.1
Glossary
Banked Register — A memory-mapped register operating on one Flash block which shares the same
register address as the equivalent registers for the other Flash blocks. The active register bank is selected
by the BKSEL bit in the FCNFG register.
Command Write Sequence — A three-step MCU instruction sequence to execute built-in algorithms
(including program and erase) on the Flash memory.
Common Register — A memory-mapped register which operates on all Flash blocks.
2.1.2
•
•
•
•
•
•
•
Features
256 Kbytes of Flash memory comprised of two 128 Kbyte blocks with each block divided into
128 sectors of 1024 bytes
Automated program and erase algorithm
Interrupts on Flash command completion, command buffer empty
Fast sector erase and word program operation
2-stage command pipeline for faster multi-word program times
Sector erase abort feature for critical interrupt response
Flexible protection scheme to prevent accidental program or erase
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
57
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
•
•
•
2.1.3
Single power supply for all Flash operations including program and erase
Security feature to prevent unauthorized access to the Flash memory
Code integrity check using built-in data compression
Modes of Operation
Program, erase, erase verify, and data compress operations (please refer to Section 2.4.1 for details).
2.1.4
Block Diagram
A block diagram of the Flash module is shown in Figure 2-1.
MC9S12HZ256 Data Sheet, Rev. 2.04
58
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
FTS256K2
Command
Interface
Common
Registers
Banked
Registers
Command
Interrupt
Request
Flash Block 0
64K * 16 Bits
sector 0
sector 1
Command Pipelines
Flash Block 0-1
comm2
addr2
data2
comm1
addr1
data1
sector 127
Flash Block 1
64K * 16 Bits
Protection
sector 0
sector 1
sector 127
Security
Oscillator
Clock
Clock
Divider FCLK
Figure 2-1. FTS256K2 Block Diagram
2.2
External Signal Description
The Flash module contains no signals that connect off-chip.
2.3
Memory Map and Register Definition
This subsection describes the memory map and registers for the Flash module.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
59
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.3.1
Module Memory Map
The Flash memory map is shown in Figure 2-2. The HCS12 architecture places the Flash memory
addresses between 0x4000 and 0xFFFF which corresponds to three 16-Kbyte pages. The content of the
HCS12 core PPAGE register is used to map the logical middle page ranging from address 0x8000 to
0xBFFF to any physical 16 Kbyte page in the Flash memory. By placing 0x3E or 0x3F in the HCS12 Core
PPAGE register, the associated 16 Kbyte pages appear twice in the MCU memory map.
The FPROT register, described in Section 2.3.2.5, “Flash Protection Register (FPROT)”, can be set to
globally protect a Flash block. However, three separate memory regions, one growing upward from the
first address in the next-to-last page in the Flash block (called the lower region), one growing downward
from the last address in the last page in the Flash block (called the higher region), and the remaining
addresses in the Flash block, can be activated for protection. The Flash locations of these protectable
regions are shown in Table 2-2. The higher address region of Flash block 0 is mainly targeted to hold the
boot loader code because it covers the vector space. The lower address region of any Flash block can be
used for EEPROM emulation in an MCU without an EEPROM module because it can remain unprotected
while the remaining addresses are protected from program or erase.
Security information that allows the MCU to restrict access to the Flash module is stored in the Flash
configuration field found in Flash block 0, described in Table 2-1.
Table 2-1. Flash Configuration Field
Unpaged
Flash Address
Paged Flash
Address
(PPAGE 0x3F)
Size
(Bytes)
0xFF00 – 0xFF07
0xBF00 – 0xBF07
8
Backdoor Comparison Key
Refer to Section 2.6.1, “Unsecuring the MCU using Backdoor Key
Access”
0xFF08 – 0xFF0B
0xBF08 – 0xBF0B
4
Reserved
0xFF0C
0xBF0C
1
Block 1 Flash Protection Byte
Refer to Section 2.3.2.7, “Flash Status Register (FSTAT)”
0xFF0D
0xBF0D
1
Block 0 Flash Protection Byte
Refer toSection 2.3.2.7, “Flash Status Register (FSTAT)”
0xFF0E
0xBF0E
1
Flash Nonvolatile Byte
Refer to Section 2.3.2.9, “Flash Control Register (FCTL)”
0xFF0F
0xBF0F
1
Flash Security Byte
Refer to Section 2.3.2.2, “Flash Security Register (FSEC)”
Description
MC9S12HZ256 Data Sheet, Rev. 2.04
60
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
(16 bytes)
MODULE BASE + 0x0000
Flash Registers
MODULE BASE + 0x000F
FLASH_START = 0x4000
0x4400
0x4800
Flash Protected Low Sectors
1, 2, 4, 8 Kbytes
0x5000
0x6000
0x3E
0x8000
Flash Blocks
16K PAGED
MEMORY
0x38
0x39
0x3A
0x3B 0x3C
0x3D
0x3E
0x3F
Block 0
0xC000
0x30
0x31
0x32
0x33
0x34
0x35
0x36
0x37
Block 1
0xE000
0x3F
Flash Protected High Sectors
2, 4, 8, 16 Kbytes
0xF000
0xF800
FLASH_END = 0xFFFF
0xFF00 – 0xFF0F, Flash Configuration Field
Note: 0x30–0x3F correspond to the PPAGE register content
Figure 2-2. Flash Memory Map
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
61
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Table 2-2. Detailed Flash Memory Map
MCU Address
Range
0x4000–0x7FFF
PPAGE
Unpaged
(0x3E)
Protectable Lower
Range
Protectable Higher
Range
Flash
Block
Block Relative
Address1
0x4000–0x43FF
N.A.
0
0x018000–0x01BFFF
1
0x4000–0x47FF
0x4000–0x4FFF
0x4000–0x5FFF
0x8000–0xBFFF
0x30
N.A.
N.A.
0x31
N.A.
N.A.
0x004000–0x007FFF
0x000000–0x003FFF
0x32
N.A.
N.A.
0x008000–0x00BFFF
0x33
N.A.
N.A.
0x00C000–0x00FFFF
0x34
N.A.
N.A.
0x010000–0x013FFF
0x35
N.A.
N.A.
0x014000–0x017FFF
0x36
0x8000–0x83FF
N.A.
0x018000–0x01BFFF
0xB800–0xBFFF
0x01C000–0x01FFFF
0x8000–0x87FF
0x8000–0x8FFF
0x8000–0x9FFF
0x37
N.A.
0xB000–0xBFFF
0xA000–0xBFFF
0x8000–0xBFFF
0x8000–0xBFFF
0x38
N.A.
N.A.
0
0x000000–0x003FFF
0x39
N.A.
N.A.
0x3A
N.A.
N.A.
0x008000–0x00BFFF
0x3B
N.A.
N.A.
0x00C000–0x00FFFF
0x3C
N.A.
N.A.
0x010000–0x013FFF
0x3D
N.A.
N.A.
0x014000–0x017FFF
0x3E
0x8000–0x83FF
N.A.
0x018000–0x01BFFF
0xB800–0xBFFF
0x01C000–0x01FFFF
0x004000–0x007FFF
0x8000–0x87FF
0x8000–0x8FFF
0x8000–0x9FFF
0x3F
N.A.
0xB000–0xBFFF
0xA000–0xBFFF
0x8000–0xBFFF
0xC000–0xFFFF
Unpaged
(0x3F)
N.A.
0xF800–0xFFFF
0
0x01C000–0x01FFFF
0xF000–0xFFFF
0xE000–0xFFFF
0xC000–0xFFFF
1
Block relative address for each 128 Kbyte Flash block consists of 17 address bits.
MC9S12HZ256 Data Sheet, Rev. 2.04
62
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
The Flash module also contains a set of 16 control and status registers located in address space module
base + 0x0000 to module base + 0x000F. In order to accommodate more than one Flash block with a
minimum register address space, a set of registers located from module base + 0x0004 to module
base + 0x000B are repeated in all banks. The active register bank is selected by the BKSEL bits in the
unbanked Flash configuration register (FCNFG). A summary of these registers is given in Table 2-3 while
their accessibility in normal and special modes is detailed in Section 2.3.2, “Register Descriptions”.
Table 2-3. Flash Register Map
Module
Base +
1
Register Name
0x0000
Flash Clock Divider Register (FCLKDIV)
0x0001
Flash Security Register (FSEC)
(FTSTMOD)1
Normal Mode
Access
R/W
R
0x0002
Flash Test Mode Register
R
0x0003
Flash Configuration Register (FCNFG)
R/W
0x0004
Flash Protection Register (FPROT)
R/W
0x0005
Flash Status Register (FSTAT)
R/W
0x0006
Flash Command Register (FCMD)
R/W
0x0007
Flash Control Register (FCTL)
R
0x0008
Flash High Address Register (FADDRHI)1
R
0x0009
Flash Low Address Register (FADDRLO)1
R
0x000A
Flash High Data Register (FDATAHI)
R
0x000B
Flash Low Data Register (FDATALO)
R
0x000C
RESERVED11
R
0x000D
RESERVED21
R
0x000E
RESERVED31
R
0x000F
RESERVED41
R
Intended for factory test purposes only.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
63
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.3.2
Register Descriptions
Register
Name
FCLKDIV
Bit 7
R
6
5
4
3
2
1
Bit 0
PRDIV8
FDIV5
FDIV4
FDIV3
FDIV2
FDIV1
FDIV0
RNV5
RNV4
RNV3
RNV2
0
0
0
0
0
0
FDIVLD
W
FSEC
R
KEYEN
SEC
W
FTSTMOD
R
0
0
0
0
WRALL
W
FCNFG
R
0
CBEIE
CCIE
KEYACC
BKSEL
W
FPROT
R
RNV6
FPOPEN
FPHDIS
FPHS
FPLDIS
FPLS
W
FSTAT
R
CCIF
CBEIF
0
PVIOL
BLANK
0
0
NV2
NV1
NV0
0
0
0
ACCERR
W
FCMD
R
0
CMDB
W
FCTL
R
NV7
NV6
NV5
NV4
NV3
W
FADDRHI
R
FADDRHI
W
FADDRLO
R
FADDRLO
W
FDATAHI
R
FDATAHI
W
FDATALO
R
FDATALO
W
RESERVED1
R
0
0
0
0
0
W
= Unimplemented or Reserved
Figure 2-3. FTS256K2 Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
64
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Register
Name
RESERVED2
R
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
RESERVED3
R
W
RESERVED4
R
W
= Unimplemented or Reserved
Figure 2-3. FTS256K2 Register Summary (continued)
2.3.2.1
Flash Clock Divider Register (FCLKDIV)
The unbanked FCLKDIV register is used to control timed events in program and erase algorithms.
7
R
6
5
4
3
2
1
0
PRDIV8
FDIV5
FDIV4
FDIV3
FDIV2
FDIV1
FDIV0
0
0
0
0
0
0
0
FDIVLD
W
Reset
0
= Unimplemented or Reserved
Figure 2-4. Flash Clock Divider Register (FCLKDIV)
All bits in the FCLKDIV register are readable, bits 6-0 are write once and bit 7 is not writable.
Table 2-4. FCLKDIV Field Descriptions
Field
Description
7
FDIVLD
Clock Divider Loaded.
0 Register has not been written.
1 Register has been written to since the last reset.
6
PRDIV8
Enable Prescalar by 8.
0 The oscillator clock is directly fed into the clock divider.
1 The oscillator clock is divided by 8 before feeding into the clock divider.
5-0
FDIV[5:0]
2.3.2.2
Clock Divider Bits — The combination of PRDIV8 and FDIV[5:0] must divide the oscillator clock down to a
frequency of 150 kHz–200 kHz. The maximum divide ratio is 512. Please refer to Section 2.4.1.1, “Writing the
FCLKDIV Register” for more information.
Flash Security Register (FSEC)
The unbanked FSEC register holds all bits associated with the security of the MCU and Flash module.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
65
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
7
R
6
KEYEN
5
4
3
2
RNV5
RNV4
RNV3
RNV2
F
F
F
F
1
0
SEC
W
Reset
F
F
F
F
= Unimplemented or Reserved
Figure 2-5. Flash Security Register (FSEC)
All bits in the FSEC register are readable but are not writable.
The FSEC register is loaded from the Flash Configuration Field at address $FF0F during the reset
sequence, indicated by F in Figure 2-5.
Table 2-5. FSEC Field Descriptions
Field
Description
1-0
Backdoor Key Security Enable Bits —The KEYEN[1:0] bits define the enabling of backdoor key access to the
KEYEN[1:0] Flash module as shown in Table 2-6.
5-2
RNV[5:2]
Reserved Nonvolatile Bits — The RNV[5:2] bits must remain in the erased 1 state for future enhancements.
1-0
SEC[1:0]
Flash Security Bits — The SEC[1:0] bits define the security state of the MCU as shown in Table 2-7. If the Flash
module is unsecured using backdoor key access, the SEC bits are forced to 10.
Table 2-6. Flash KEYEN States
1
KEYEN[1:0]
Status of Backdoor Key Access
00
DISABLED
011
DISABLED
10
ENABLED
11
DISABLED
Preferred KEYEN state to disable Backdoor Key Access.
Table 2-7. Flash Security States
SEC[1:0]
Status of Security
00
SECURED
1
SECURED
01
1
10
UNSECURED
11
SECURED
Preferred SEC state to set MCU to secured state.
The security function in the Flash module is described in Section 2.6, “Flash Module Security”.
MC9S12HZ256 Data Sheet, Rev. 2.04
66
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.3.2.3
Flash Test Mode Register (FTSTMOD)
The unbanked FTSTMOD register is used to control Flash test features.
R
7
6
5
0
0
0
4
3
2
1
0
0
0
0
0
0
0
0
0
WRALL
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 2-6. Flash Test Mode Register (FTSTMOD)
All bits read 0 and are not writable in normal mode. The WRALL bit is writable only in special mode to
simplify mass erase and erase verify operations. When writing to the FTSTMOD register in special mode,
all unimplemented/reserved bits must be written to 0.
Table 2-8. FTSTMOD Field Descriptions
Field
Description
4
WRALL
Write to All Register Banks — If the WRALL bit is set, all banked registers sharing the same register address
will be written simultaneously during a register write.
0 Write only to the bank selected via BKSEL.
1 Write to all register banks.
2.3.2.4
Flash Configuration Register (FCNFG)
The unbanked FCNFG register enables the Flash interrupts and gates the security backdoor writes.
7
6
5
CBEIE
CCIE
KEYACC
0
0
0
R
4
3
2
1
0
0
0
0
0
BKSEL
W
Reset
0
0
0
0
0
= Unimplemented or Reserved
Figure 2-7. Flash Configuration Register (FCNFG)
CBEIE, CCIE, KEYACC and BKSEL bits are readable and writable while all remaining bits read 0 and
are not writable. KEYACC is only writable if KEYEN (see Section 2.3.2.2) is set to the enabled state.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
67
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Table 2-9. FCNFG Field Descriptions
Field
Description
7
CBEIE
Command Buffer Empty Interrupt Enable — The CBEIE bit enables an interrupt in case of an empty command
buffer in the Flash module.
0 Command buffer empty interrupt disabled.
1 An interrupt will be requested whenever the CBEIF flag (see Section 2.3.2.7, “Flash Status Register (FSTAT)”)
is set.
6
CCIE
Command Complete Interrupt Enable — The CCIE bit enables an interrupt in case all commands have been
completed in the Flash module.
0 Command complete interrupt disabled.
1 An interrupt will be requested whenever the CCIF flag (see Section 2.3.2.7, “Flash Status Register (FSTAT)”)
is set.
5
KEYACC
0
BKSEL
2.3.2.5
Enable Security Key Writing
0 Flash writes are interpreted as the start of a command write sequence.
1 Writes to Flash array are interpreted as keys to open the backdoor. Reads of the Flash array return invalid
data.
Block Select — The BKSEL bit indicates which register bank is active.
0 Select register bank associated with Flash block 0.
1 Select register bank associated with Flash block 1.
Flash Protection Register (FPROT)
The banked FPROT register defines which Flash sectors are protected against program or erase operations.
7
R
6
5
4
3
2
1
0
RNV6
FPOPEN
FPHDIS
FPHS
FPLDIS
FPLS
W
Reset
F
F
F
F
F
F
F
F
= Unimplemented or Reserved
Figure 2-8. Flash Protection Register (FPROT)
All bits in the FPROT register are readable and writable with restrictions except for RNV[6] which is only
readable (see Section 2.3.2.6, “Flash Protection Restrictions”).
During reset, the banked FPROT registers are loaded from the Flash Configuration Field at the address
shown in Table 2-10. To change the Flash protection that will be loaded during the reset sequence, the
upper sector of the Flash memory must be unprotected, then the Flash Protect/Security byte located as
described in Table 2-1 must be reprogrammed.
Table 2-10. Reset Loading of FPROT
Flash Address
Protection Byte for
0xFF0D
Flash Block 0
0xFF0C
Flash Block 1
MC9S12HZ256 Data Sheet, Rev. 2.04
68
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Trying to alter data in any of the protected areas in the Flash block will result in a protection violation error
and the PVIOL flag will be set in the FSTAT register. A mass erase of the Flash block is not possible if
any of the contained Flash sectors are protected.
Table 2-11. FPROT Field Descriptions
Field
Description
7
FPOPEN
Protection Function Bit — The FPOPEN bit determines the protection function for program or erase as shown
in Table 2-12.
0 FPHDIS and FPLDIS bits define unprotected address ranges as specified by the corresponding FPHS[1:0]
and FPLS[1:0] bits. For an MCU without an EEPROM module, the FPOPEN clear state allows the main part
of the Flash block to be protected while a small address range can remain unprotected for EEPROM
emulation.
1 FPHDIS and FPLDIS bits enable protection for the address range specified by the corresponding FPHS[1:0]
and FPLS[1:0] bits.
6
RNV[6]
Reserved Nonvolatile Bit — The RNV[6] bit must remain in the erased state 1 for future enhancements.
5
FPHDIS
Flash Protection Higher Address Range Disable — The FPHDIS bit determines whether there is a
protected/unprotected area in the higher address space of the Flash block.
0 Protection/Unprotection enabled
1 Protection/Unprotection disabled
4:3
FPHS[1:0]
2
FPLDIS
1:0
FPLS[1:0]
Flash Protection Higher Address Size — The FPHS[1:0] bits determine the size of the protected/unprotected
area as shown in Table 2-13. The FPHS[1:0] bits can only be written to while the FPHDIS bit is set.
Flash Protection Lower address range Disable — The FPLDIS bit determines whether there is a
protected/unprotected area in the lower address space of the Flash block.
0 Protection/Unprotection enabled
1 Protection/Unprotection disabled
Flash Protection Lower Address Size — The FPLS[1:0] bits determine the size of the protected/unprotected
area as shown in Table 2-14. The FPLS[1:0] bits can only be written to while the FPLDIS bit is set.
Table 2-12. Flash Protection Function
1
Function1
FPOPEN
FPHDIS
FPLDIS
1
1
1
No Protection
1
1
0
Protected Low Range
1
0
1
Protected High Range
1
0
0
Protected High and Low Ranges
0
1
1
Full Block Protected
0
1
0
Unprotected Low Range
0
0
1
Unprotected High Range
0
0
0
Unprotected High and Low Ranges
For range sizes, refer to Table 2-13 and Table 2-14.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
69
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Table 2-13. Flash Protection Higher Address Range
FPHS[1:0]
Unpaged
Address Range
Paged
Address Range
Protected Size
00
0xF800–0xFFFF
0x0037/0x003F: 0xC800–0xCFFF
2 Kbytes
01
0xF000–0xFFFF
0x0037/0x003F: 0xC000–0xCFFF
4 Kbytes
10
0xE000–0xFFFF
0x0037/0x003F: 0xB000–0xCFFF
8 Kbytes
11
0xC000–0xFFFF
0x0037/0x003F: 0x8000–0xCFFF
16 Kbytes
Table 2-14. Flash Protection Lower Address Range
FPLS[1:0]
Unpaged
Address Range
Paged
Address Range
Protected Size
00
0x4000–0x43FF
0x0036/0x003E: 0x8000–0x83FF
1 Kbyte
01
0x4000–0x47FF
0x0036/0x003E: 0x8000–0x87FF
2 Kbytes
10
0x4000–0x4FFF
0x0036/0x003E: 0x8000–0x8FFF
4 Kbytes
11
0x4000–0x5FFF
0x0036/0x003E: 0x8000–0x9FFF
8 Kbytes
All possible Flash protection scenarios are illustrated in Figure 2-9. Although the protection scheme is
loaded from the Flash array after reset, it can be changed by the user. This protection scheme can be used
by applications requiring re-programming in single-chip mode while providing as much protection as
possible if re-programming is not required.
MC9S12HZ256 Data Sheet, Rev. 2.04
70
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Scenario
FPHDIS = 1
FPLDIS = 1
FPHDIS = 1
FPLDIS = 0
FPHDIS = 0
FPLDIS = 1
FPHDIS = 0
FPLDIS = 0
7
6
5
4
3
2
1
0
FPOPEN = 1
FPLS[1:0]
PPAGE 0x0030–0x0035
0x0038–0x003D
Scenario
FPHS[1:0]
PPAGE 0x0036–0x0037
0x003E–0x003F
FPHS[1:0]
PPAGE 0x0036–0x0037
0x003E–0x003F
FPOPEN = 0
FPLS[1:0]
PPAGE 0x0030–0x0035
0x0038–0x003D
Unprotected region
Protected region with size
defined by FPLS
Protected region
not defined by FPLS, FPHS
Protected region with size
defined by FPHS
Figure 2-9. Flash Protection Scenarios
2.3.2.6
Flash Protection Restrictions
The general guideline is that Flash protection can only be added and not removed. Table 2-15 specifies all
valid transitions between Flash protection scenarios. Any attempt to write an invalid scenario to the
FPROT register will be ignored and the FPROT register will remain unchanged. The contents of the
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
71
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
FPROT register reflect the active protection scenario. See the FPHS and FPLS descriptions for additional
restrictions.
Table 2-15. Flash Protection Scenario Transitions
To Protection Scenario1
From
Protection
Scenario
0
1
2
3
0
X
X
X
X
1
X
2
X
4
X
X
X
X
X
X
X
X
X
X
7
2.3.2.7
X
X
6
7
X
3
6
5
X
X
5
1
4
X
X
X
X
X
X
Allowed transitions marked with X.
Flash Status Register (FSTAT)
The banked FSTAT register defines the operational status of the module.
7
R
6
5
4
PVIOL
ACCERR
0
0
CCIF
CBEIF
3
2
1
0
0
BLANK
0
0
0
0
0
0
1
0
W
Reset
1
1
= Unimplemented or Reserved
Figure 2-10. Flash Status Register (FSTAT - Normal Mode)
7
R
6
5
4
PVIOL
ACCERR
0
0
CCIF
CBEIF
3
2
0
BLANK
0
FAIL
W
Reset
1
1
0
0
0
0
= Unimplemented or Reserved
Figure 2-11. Flash Status Register (FSTAT - Special Mode)
CBEIF, PVIOL, and ACCERR are readable and writable, CCIF and BLANK are readable and not writable,
remaining bits read 0and are not writable in normal mode. FAIL is readable and writable in special mode.
FAIL must be clear when starting a command write sequence.
MC9S12HZ256 Data Sheet, Rev. 2.04
72
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Table 2-16. FSTAT Field Descriptions
Field
Description
7
CBEIF
Command Buffer Empty Interrupt Flag — The CBEIF flag indicates that the address, data and command
buffers are empty so that a new command write sequence can be started. The CBEIF flag is cleared by writing
a 1 to CBEIF. Writing a 0 to the CBEIF flag has no effect on CBEIF. Writing a 0 to CBEIF after writing an aligned
word to the Flash address space but before CBEIF is cleared will abort a command write sequence and cause
the ACCERR flag to be set. Writing a 0 to CBEIF outside of a command write sequence will not set the ACCERR
flag. The CBEIF flag is used together with the CBEIE bit in the FCNFG register to generate an interrupt request
(see Figure 2-29).
0 Buffers are full.
1 Buffers are ready to accept a new command.
6
CCIF
Command Complete Interrupt Flag — The CCIF flag indicates that there are no more commands pending. The
CCIF flag is cleared when CBEIF is clear and sets automatically upon completion of all active and pending
commands. The CCIF flag does not set when an active commands completes and a pending command is
fetched from the command buffer. Writing to the CCIF flag has no effect on CCIF. The CCIF flag is used together
with the CCIE bit in the FCNFG register to generate an interrupt request (see Figure 2-29).
0 Command in progress.
1 All commands are completed.
5
PVIOL
Protection Violation Flag — The PVIOL flag indicates an attempt was made to program or erase an address
in a protected area of the Flash block during a command write sequence. The PVIOL flag is cleared by writing a
1 to PVIOL. Writing a 0 to the PVIOL flag has no effect on PVIOL. While PVIOL is set, it is not possible to launch
a command or start a command write sequence.
0 No failure.
1 A protection violation has occurred.
4
ACCERR
Access Error Flag — The ACCERR flag indicates an illegal access to the Flash array caused by either a
violation of the command write sequence, issuing an illegal command (illegal combination of the CMDBx bits in
the FCMD register), launching the sector erase abort command terminating a sector erase operation early or the
execution of a CPU STOP instruction while a command is executing (CCIF = 0). The ACCERR flag is cleared by
writing a 1 to ACCERR. Writing a 0 to the ACCERR flag has no effect on ACCERR. While ACCERR is set in any
of the banked FTSAT registers, it is not possible to launch a command or start a command write sequence in any
of the Flash blocks. If ACCERR is set by an erase verify operation or a data compress operation, any buffered
command will not launch.
0 No access error detected.
1 Access error has occurred.
2
BLANK
Erase Verify Operation Status Flag — When the CCIF flag is set after completion of an erase verify command,
the BLANK flag indicates the result of the erase verify operation. The BLANK flag is cleared by the Flash module
when CBEIF is cleared as part of a new valid command write sequence. Writing to the BLANK flag has no effect
on BLANK.
0 Flash block verified as not erased.
1 Flash block verified as erased.
1
FAIL
Flag Indicating a Failed Flash Operation — The FAIL flag will set if the erase verify operation fails (selected
Flash block verified as not erased). The FAIL flag is cleared by writing a 1 to FAIL. Writing a 0 to the FAIL flag
has no effect on FAIL.
0 Flash operation completed without error.
1 Flash operation failed.
2.3.2.8
Flash Command Register (FCMD)
The banked FCMD register is the Flash command register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
73
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
7
R
6
5
4
3
0
0
1
0
0
0
0
CMDB
W
Reset
2
0
0
0
0
= Unimplemented or Reserved
Figure 2-12. Flash Command Register (FCMD - NVM User Mode)
All CMDB bits are readable and writable during a command write sequence while bit 7 reads 0 and is not
writable.
Table 2-17. FCMD Field Descriptions
Field
6-0
CMDB[6:0]
Description
Flash Command — Valid Flash commands are shown in Table 2-18. Writing any command other than those
listed in Table 2-18 sets the ACCERR flag in the FSTAT register.
Table 2-18. Valid Flash Command List
2.3.2.9
CMDB[6:0]
NVM Command
0x05
0x06
0x20
0x40
0x41
0x47
Erase Verify
Data Compress
Word Program
Sector Erase
Mass Erase
Sector Erase Abort
Flash Control Register (FCTL)
The banked FCTL register is the Flash control register.
R
7
6
5
4
3
2
1
0
NV7
NV6
NV5
NV4
NV3
NV2
NV1
NV0
F
F
F
F
F
F
F
F
W
Reset
= Unimplemented or Reserved
Figure 2-13. Flash Control Register (FCTL)
All bits in the FCTL register are readable but are not writable.
The FCTL register is loaded from the Flash Configuration Field byte at $FF0E during the reset sequence,
indicated by F in Figure 2-13.
Table 2-19. FCTL Field Descriptions
Field
Description
7-0
NV[7:0]
Nonvolatile Bits — The NV[7:0] bits are available as nonvolatile bits. Refer to the Device User Guide for proper
use of the NV bits.
MC9S12HZ256 Data Sheet, Rev. 2.04
74
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.3.2.10
Flash Address Registers (FADDR)
The banked FADDRHI and FADDRLO registers are the Flash address registers.
7
6
5
4
R
3
2
1
0
0
0
0
0
FADDRHI
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 2-14. Flash Address High Register (FADDRHI)
7
6
5
4
R
3
2
1
0
0
0
0
0
FADDRLO
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 2-15. Flash Address Low Register (FADDRLO)
All FADDRHI and FADDRLO bits are readable but are not writable. After an array write as part of a
command write sequence, the FADDR registers will contain the mapped MCU address written.
2.3.2.11
Flash Data Registers (FDATA)
The banked FDATAHI and FDATALO registers are the Flash data registers.
7
6
5
4
R
3
2
1
0
0
0
0
0
FDATAHI
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 2-16. Flash Data High Register (FDATAHI)
7
6
5
4
R
3
2
1
0
0
0
0
0
FDATALO
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 2-17. Flash Data Low Register (FDATALO)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
75
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
All FDATAHI and FDATALO bits are readable but are not writable. After an array write as part of a
command write sequence, the FDATA registers will contain the data written. At the completion of a data
compress operation, the resulting 16-bit signature is stored in the FDATA registers. The data compression
signature is readable in the FDATA registers until a new command write sequence is started.
2.3.2.12
RESERVED1
This register is reserved for factory testing and is not accessible.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 2-18. RESERVED1
All bits read 0 and are not writable.
2.3.2.13
RESERVED2
This register is reserved for factory testing and is not accessible.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 2-19. RESERVED2
All bits read 0 and are not writable.
2.3.2.14
RESERVED3
This register is reserved for factory testing and is not accessible.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 2-20. RESERVED3
All bits read 0 and are not writable.
MC9S12HZ256 Data Sheet, Rev. 2.04
76
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.3.2.15
RESERVED4
This register is reserved for factory testing and is not accessible.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 2-21. RESERVED4
All bits read 0 and are not writable.
2.4
2.4.1
Functional Description
Flash Command Operations
Write and read operations are both used for the program, erase, erase verify, and data compress algorithms
described in this subsection. The program and erase algorithms are time controlled by a state machine
whose timebase, FCLK, is derived from the oscillator clock via a programmable divider. The command
register as well as the associated address and data registers operate as a buffer and a register (2-stage FIFO)
so that a second command along with the necessary data and address can be stored to the buffer while the
first command remains in progress. This pipelined operation allows a time optimization when
programming more than one word on a specific row in the Flash block as the high voltage generation can
be kept active in between two programming commands. The pipelined operation also allows a
simplification of command launching. Buffer empty as well as command completion are signalled by flags
in the Flash status register with interrupts generated, if enabled.
The next paragraphs describe:
1. How to write the FCLKDIV register.
2. Command write sequences used to program, erase, and verify the Flash memory.
3. Valid Flash commands.
4. Effects resulting from illegal Flash command write sequences or aborting Flash operations.
2.4.1.1
Writing the FCLKDIV Register
Prior to issuing any program, erase, erase verify, or data compress command, it is first necessary to write
the FCLKDIV register to divide the oscillator clock down to within the 150 kHz to 200 kHz range.
Because the program and erase timings are also a function of the bus clock, the FCLKDIV determination
must take this information into account.
If we define:
• FCLK as the clock of the Flash timing control block,
• Tbus as the period of the bus clock, and
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
77
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
•
INT(x) as taking the integer part of x (e.g. INT(4.323)=4).
Then, FCLKDIV register bits PRDIV8 and FDIV[5:0] are to be set as described in Figure 2-22.
For example, if the oscillator clock frequency is 950 kHz and the bus clock frequency is 10 MHz,
FCLKDIV bits FDIV[5:0] must be set to 4 (000100) and bit PRDIV8 set to 0. The resulting FCLK
frequency is then 190 kHz. As a result, the Flash program and erase algorithm timings are increased over
the optimum target by:
( 200 – 190 ) ⁄ 200 × 100 = 5%
CAUTION
Program and erase command execution time will increase proportionally
with the period of FCLK. Because of the impact of clock synchronization
on the accuracy of the functional timings, programming or erasing the Flash
memory cannot be performed if the bus clock runs at less than 1 MHz.
Programming or erasing the Flash memory with FCLK < 150 kHz must be
avoided. Setting FCLKDIV to a value such that FCLK < 150 kHz can
destroy the Flash memory due to overstress. Setting FCLKDIV to a value
such that (1/FCLK + Tbus) < 5µs can result in incomplete programming or
erasure of the Flash memory cells.
If the FCLKDIV register is written, the FDIVLD bit is set automatically. If the FDIVLD bit is 0, the
FCLKDIV register has not been written since the last reset. Flash commands will not be executed if the
FCLKDIV register has not been written to.
MC9S12HZ256 Data Sheet, Rev. 2.04
78
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
START
Tbus < 1µs?
NO
ALL COMMANDS IMPOSSIBLE
YES
PRDIV8=0 (reset)
OSCILLATOR
CLOCK
> 12.8 MHZ?
NO
YES
PRDIV8=1
PRDCLK=oscillator_clock/8
PRDCLK[MHz]*(5+Tbus[µs])
an integer?
YES
PRDCLK=oscillator_clock
NO
FDIV[5:0]=INT(PRDCLK[MHz]*(5+Tbus[µs]))
FDIV[5:0]=PRDCLK[MHz]*(5+Tbus[µs])-1
TRY TO DECREASE Tbus
FCLK=(PRDCLK)/(1+FDIV[5:0])
1/FCLK[MHz] + Tbus[µs] > 5
AND
FCLK > 0.15 MHz
?
YES
END
NO
YES
FDIV[5:0] > 4?
NO
ALL COMMANDS IMPOSSIBLE
Figure 2-22. Determination Procedure for PRDIV8 and FDIV Bits
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
79
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.2
Command Write Sequence
The Flash command controller is used to supervise the command write sequence to execute program,
erase, erase verify, and data compress algorithms.
Before starting a command write sequence, the ACCERR and PVIOL flags in the FSTAT register must be
clear (see Section 2.3.2.7, “Flash Status Register (FSTAT)”) and the CBEIF flag must be tested to
determine the state of the address, data, and command buffers. If the CBEIF flag is set, indicating the
buffers are empty, a new command write sequence can be started. If the CBEIF flag is clear, indicating the
buffers are not available, a new command write sequence will overwrite the contents of the address, data,
and command buffers.
A command write sequence consists of three steps which must be strictly adhered to with writes to the
Flash module not permitted between the steps. However, Flash register and array reads are allowed during
a command write sequence. A command write sequence consists of the following steps:
1. Write an aligned data word to a valid Flash array address. The address and data will be stored in
the address and data buffers, respectively. If the CBEIF flag is clear when the Flash array write
occurs, the contents of the address and data buffers will be overwritten and the CBEIF flag will be
set.
2. Write a valid command to the FCMD register.
a) For the erase verify command (see Section 2.4.1.3.1, “Erase Verify Command”), the contents
of the data buffer are ignored and all address bits in the address buffer are ignored.
b) For the data compress command (see Section 2.4.1.3.2, “Data Compress Command”), the
contents of the data buffer represents the number of consecutive words to read for data
compression and the contents of the address buffer represents the starting address.
c) For the program command (see Section 2.4.1.3.3, “Program Command”), the contents of the
data buffer will be programmed to the address specified in the address buffer with all address
bits valid.
d) For the sector erase command (see Section 2.4.1.3.4, “Sector Erase Command”), the contents
of the data buffer are ignored and address bits [9:0] contained in the address buffer are ignored.
e) For the mass erase command (see Section 2.4.1.3.5, “Mass Erase Command”), the contents of
the data buffer and address buffer are ignored.
f) For the sector erase abort command (see Section 2.4.1.3.6, “Sector Erase Abort Command”),
the contents of the data buffer and address buffer are ignored.
3. Clear the CBEIF flag by writing a 1 to CBEIF to launch the command. When the CBEIF flag is
cleared, the CCIF flag is cleared on the same bus cycle by internal hardware indicating that the
command was successfully launched. For all command write sequences except data compress and
sector erase abort, the CBEIF flag will set four bus cycles after the CCIF flag is cleared indicating
that the address, data, and command buffers are ready for a new command write sequence to begin.
For data compress and sector erase abort operations, the CBEIF flag will remain clear until the
operation completes.
A command write sequence can be aborted prior to clearing the CBEIF flag by writing a 0 to the CBEIF
flag and will result in the ACCERR flag being set.
MC9S12HZ256 Data Sheet, Rev. 2.04
80
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Except for the sector erase abort command, a buffered command will wait for the active operation to be
completed before being launched. The sector erase abort command is launched when the CBEIF flag is
cleared as part of a sector erase abort command write sequence. After a command is launched, the
completion of the command operation is indicated by the setting of the CCIF flag. The CCIF flag only sets
when all active and buffered commands have been completed.
2.4.1.3
Valid Flash Commands
Table 2-20 summarizes the valid Flash commands along with the effects of the commands on the Flash
block.
Table 2-20. Valid Flash Command Description
FCMDB
0x05
0x06
NVM
Command
Function on Flash Memory
Erase
Verify
Verify all memory bytes in the Flash block are erased. If the Flash block is erased, the BLANK
flag in the FSTAT register will set upon command completion.
Data
Compress data from a selected portion of the Flash block. The resulting signature is stored in
Compress the FDATA register.
0x20
Program
Program a word (two bytes) in the Flash block.
0x40
Sector
Erase
Erase all memory bytes in a sector of the Flash block.
0x41
Mass
Erase
Erase all memory bytes in the Flash block. A mass erase of the full Flash block is only possible
when FPLDIS, FPHDIS, and FPOPEN bits in the FPROT register are set prior to launching the
command.
0x47
Sector
Erase
Abort
Abort the sector erase operation. The sector erase operation will terminate according to a set
procedure. The Flash sector must not be considered erased if the ACCERR flag is set upon
command completion.
CAUTION
A Flash word must be in the erased state before being programmed.
Cumulative programming of bits within a Flash word is not allowed.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
81
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.3.1
Erase Verify Command
The erase verify operation is used to confirm that a Flash block is erased. After launching the erase verify
command, the CCIF flag in the FSTAT register will set after the operation has completed unless a second
command has been buffered. The number of bus cycles required to execute the erase verify operation is
equal to the number of addresses in the Flash block plus 12 bus cycles as measured from the time the
CBEIF flag is cleared until the CCIF flag is set. The result of the erase verify operation is reflected in the
state of the BLANK flag in the FSTAT register. If the BLANK flag is set in the FSTAT register, the Flash
memory is erased.
Read: Register FCLKDIV
Clock Register
Loaded
Check
no
Bit FDIVLD set?
yes
Write: Register FCLKDIV
1.
Write: Flash Block Address
and Dummy Data
2.
Write: Register FCMD
Erase Verify Command 0x05
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
3.
Write: Register FSTAT
Clear bit CBEIF 0x80
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
Read: Register FSTAT
Access
Error Check
Bit
ACCERR
Set?
yes
Write: Register FSTAT
Clear bit ACCERR 0x10
no
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
no
Read: Register FSTAT
yes
Bit
BLANK
Set?
no
Flash Block Not Erased;
Mass Erase Flash Block
yes
EXIT
Figure 2-23. Example Erase Verify Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
82
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.3.2
Data Compress Command
The data compress command is used to check Flash code integrity by compressing data from a selected
portion of the Flash block into a signature analyzer. The starting address for the data compress operation
is defined by the address written during the command write sequence. The number of consecutive word
addresses compressed is defined by the data written during the command write sequence. If the data value
written is 0x0000, 64K addresses or 128 Kbytes will be compressed. After launching the data compress
command, the CCIF flag in the FSTAT register will set after the data compress operation has completed.
The number of bus cycles required to execute the data compress operation is equal to two times the number
of addresses read plus 20 bus cycles as measured from the time the CBEIF flag is cleared until the CCIF
flag is set. After the CCIF flag is set, the signature generated by the data compress operation is available
in the FDATA register. The signature in the FDATA register can be compared to the expected signature
to determine the integrity of the selected data stored in the Flash block. If the last address of the Flash block
is reached during the data compress operation, data compression will continue with the starting address of
the Flash block.
NOTE
Since the FDATA register (or data buffer) is written to as part of the data
compress operation, a command write sequence is not allowed to be
buffered behind a data compress command write sequence. The CBEIF flag
will not set after launching the data compress command to indicate that a
command must not be buffered behind it. If an attempt is made to start a new
command write sequence with a data compress operation active, the
ACCERR flag in the FSTAT register will be set. A new command write
sequence must only be started after reading the signature stored in the
FDATA register.
In order to take corrective action, it is recommended that the data compress command be executed on a
Flash sector or subset of a Flash sector. If the data compress operation on a Flash sector returns an invalid
signature, the Flash sector must be erased using the sector erase command and then reprogrammed using
the program command.
The data compress command can be used to verify that a sector or sequential set of sectors are erased.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
83
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Read: Register FCLKDIV
Clock Register
Loaded
Check
Bit FDIVLD set?
yes
no
Write: Register FCLKDIV
1.
Write: Flash address to start
compression and number of
word addresses to compress
2.
Write: Register FCMD
Data Compress Command 0x06
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
3.
Write: Register FSTAT
Clear bit CBEIF 0x80
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
Read: Register FSTAT
Bit
ACCERR
Set?
Access
Error Check
yes
Write: Register FSTAT
Clear bit ACCERR 0x10
no
Bit
CCIF
Set?
Bit Polling for
Command
Completion Check
no
Read: Register FSTAT
yes
Read: Register FDATA
Data Compress Signature
Signature
Compared to
Known Value
Signature
Valid?
no
Erase and Reprogram
Flash Region Compressed
yes
EXIT
Figure 2-24. Example Data Compress Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
84
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.3.3
Program Command
The program command is used to program a previously erased word in the Flash memory using an
embedded algorithm. If the word to be programmed is in a protected area of the Flash block, the PVIOL
flag in the FSTAT register will set and the program command will not launch. After the program command
has successfully launched, the CCIF flag in the FSTAT register will set after the program operation has
completed unless a second command has been buffered.
A summary of the launching of a program operation is shown in Figure 2-25.
Read: Register FCLKDIV
Clock Register
Loaded
Check
no
Bit FDIVLD set?
yes
Write: Register FCLKDIV
1.
Write: Flash Address and
Program Data
2.
Write: Register FCMD
Program Command 0x20
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
3.
Write: Register FSTAT
Clear bit CBEIF 0x80
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
Read: Register FSTAT
Bit
PVIOL
Set?
Protection
Violation Check
yes
Write: Register FSTAT
Clear bit PVIOL 0x20
yes
Write: Register FSTAT
Clear bit ACCERR 0x10
no
Bit
ACCERR
Set?
Access
Error Check
no
Address, Data,
Command
Buffer Empty Check
Bit
CBEIF
Set?
yes
yes
Next Write?
no
no
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
no
Read: Register FSTAT
yes
EXIT
Figure 2-25. Example Program Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
85
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.3.4
Sector Erase Command
The sector erase command is used to erase the addressed sector in the Flash memory using an embedded
algorithm. If the Flash sector to be erased is in a protected area of the Flash block, the PVIOL flag in the
FSTAT register will set and the sector erase command will not launch. After the sector erase command
has successfully launched, the CCIF flag in the FSTAT register will set after the sector erase operation has
completed unless a second command has been buffered.
Read: Register FCLKDIV
Clock Register
Loaded
Check
no
Bit FDIVLD set?
yes
Write: Register FCLKDIV
1.
Write: Flash Sector Address
and Dummy Data
2.
Write: Register FCMD
Sector Erase Command 0x40
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
3.
Write: Register FSTAT
Clear bit CBEIF 0x80
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
Read: Register FSTAT
Protection
Violation Check
Bit
PVIOL
Set?
yes
Write: Register FSTAT
Clear bit PVIOL 0x20
no
Bit
ACCERR
Set?
Access
Error Check
yes
Write: Register FSTAT
Clear bit ACCERR 0x10
no
Address, Data,
Command
Buffer Empty Check
yes
Bit
CBEIF
Set?
yes
Next Write?
no
no
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
no
Read: Register FSTAT
yes
EXIT
Figure 2-26. Example Sector Erase Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
86
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.3.5
Mass Erase Command
The mass erase command is used to erase a Flash memory block using an embedded algorithm. If the Flash
block to be erased contains any protected area, the PVIOL flag in the FSTAT register will set and the mass
erase command will not launch. After the mass erase command has successfully launched, the CCIF flag
in the FSTAT register will set after the mass erase operation has completed unless a second command has
been buffered.
Read: Register FCLKDIV
Clock Register
Loaded
Check
no
Bit FDIVLD set?
yes
Write: Register FCLKDIV
1.
Write: Flash Block Address
and Dummy Data
2.
Write: Register FCMD
Mass Erase Command 0x41
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
3.
Write: Register FSTAT
Clear bit CBEIF 0x80
NOTE: command write sequence
aborted by writing 0x00 to
FSTAT register.
Read: Register FSTAT
Protection
Violation Check
Bit
PVIOL
Set?
yes
Write: Register FSTAT
Clear bit PVIOL 0x20
no
Bit
ACCERR
Set?
Access
Error Check
yes
Write: Register FSTAT
Clear bit ACCERR 0x10
no
Address, Data,
Command
Buffer Empty Check
yes
Bit
CBEIF
Set?
yes
Next Write?
no
no
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
no
Read: Register FSTAT
yes
EXIT
Figure 2-27. Example Mass Erase Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
87
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.3.6
Sector Erase Abort Command
The sector erase abort command is used to terminate the sector erase operation so that other sectors in the
Flash block are available for read and program operations without waiting for the sector erase operation
to complete. If the sector erase abort command is launched resulting in the early termination of an active
sector erase operation, the ACCERR flag will set after the operation completes as indicated by the CCIF
flag being set. The ACCERR flag sets to inform the user that the sector may not be fully erased and a new
sector erase command must be launched before programming any location in that specific sector. If the
sector erase abort command is launched but the active sector erase operation completes normally, the
ACCERR flag will not set upon completion of the operation as indicated by the CCIF flag being set.
Therefore, if the ACCERR flag is not set after the sector erase abort command has completed, the sector
being erased when the abort command was launched is fully erased. The maximum number of cycles
required to abort a sector erase operation is equal to four FCLK periods (see Section 2.4.1.1, “Writing the
FCLKDIV Register”) plus five bus cycles as measured from the time the CBEIF flag is cleared until the
CCIF flag is set.
NOTE
Since the ACCERR bit in the FSTAT register may be set at the completion
of the sector erase abort operation, a command write sequence is not
allowed to be buffered behind a sector erase abort command write sequence.
The CBEIF flag will not set after launching the sector erase abort command
to indicate that a command must not be buffered behind it. If an attempt is
made to start a new command write sequence with a sector erase abort
operation active, the ACCERR flag in the FSTAT register will be set. A new
command write sequence may be started after clearing the ACCERR flag, if
set.
NOTE
The sector erase abort command must be used sparingly because a sector
erase operation that is aborted counts as a complete program/erase cycle.
MC9S12HZ256 Data Sheet, Rev. 2.04
88
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Execute Sector Erase Command Flow
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
Erase
Abort
Needed?
no
yes
no
Read: Register FSTAT
yes
EXIT
1.
Write: Dummy Flash Address
and Dummy Data
NOTE: command write sequence
aborted by writing 0x00 to
2.
FSTAT register.
Write: Register FCMD
Sector Erase Abort Cmd 0x47
NOTE: command write sequence
aborted by writing 0x00 to
3.
FSTAT register.
Write: Register FSTAT
Clear bit CBEIF 0x80
Read: Register FSTAT
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
no
Read: Register FSTAT
yes
Access
Error Check
Bit
ACCERR
Set?
yes
Write: Register FSTAT
Clear bit ACCERR 0x10
no
EXIT
Sector Erase
Completed
EXIT
Sector Erase
Aborted
Figure 2-28. Example Sector Erase Abort Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
89
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.4.1.4
Illegal Flash Operations
The ACCERR flag will be set during the command write sequence if any of the following illegal steps are
performed, causing the command write sequence to immediately abort:
1. Writing to a Flash address before initializing the FCLKDIV register.
2. Writing to a Flash address in the range 0x8000–0xBFFF when the PPAGE register does not select
a 16 Kbyte page in the Flash block selected by the BKSEL bit in the FCNFG register.
3. Writing to a Flash address in the range 0x4000–0x7FFF or 0xC000–0xFFFF with the BKSEL bit
in the FCNFG register not selecting Flash block 0.
4. Writing a byte or misaligned word to a valid Flash address.
5. Starting a command write sequence while a data compress operation is active.
6. Starting a command write sequence while a sector erase abort operation is active.
7. Writing a second word to a Flash address in the same command write sequence.
8. Writing to any Flash register other than FCMD after writing a word to a Flash address.
9. Writing a second command to the FCMD register in the same command write sequence.
10. Writing an invalid command to the FCMD register.
11. When security is enabled, writing a command other than mass erase to the FCMD register when
the write originates from a non-secure memory location or from the Background Debug Mode.
12. Writing to any Flash register other than FSTAT (to clear CBEIF) after writing to the FCMD
register.
13. Writing a 0 to the CBEIF flag in the FSTAT register to abort a command write sequence.
The ACCERR flag will not be set if any Flash register is read during a valid command write sequence.
The ACCERR flag will also be set if any of the following events occur:
1. Launching the sector erase abort command while a sector erase operation is active which results in
the early termination of the sector erase operation (see Section 2.4.1.3.6, “Sector Erase Abort
Command”)
2. The MCU enters stop mode and a program or erase operation is in progress. The operation is
aborted immediately and any pending command is purged (see Section 2.5.2, “Stop Mode”).
If the Flash memory is read during execution of an algorithm (i.e., CCIF flag in the FSTAT register is low),
the read operation will return invalid data and the ACCERR flag will not be set.
If the ACCERR flag is set in the FSTAT register, the user must clear the ACCERR flag before starting
another command write sequence (see Section 2.3.2.7, “Flash Status Register (FSTAT)”).
The PVIOL flag will be set after the command is written to the FCMD register during a command write
sequence if any of the following illegal operations are attempted, causing the command write sequence to
immediately abort:
1. Writing the program command if the address written in the command write sequence was in a
protected area of the Flash memory.
2. Writing the sector erase command if the address written in the command write sequence was in a
protected area of the Flash memory.
3. Writing the mass erase command while any Flash protection is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
90
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
If the PVIOL flag is set in the FSTAT register, the user must clear the PVIOL flag before starting another
command write sequence (see Section 2.3.2.7, “Flash Status Register (FSTAT)”).
2.5
2.5.1
Operating Modes
Wait Mode
If a command is active (CCIF = 0) when the MCU enters wait mode, the active command and any buffered
command will be completed.
The Flash module can recover the MCU from wait mode if the CBEIF and CCIF interrupts are enabled
(Section 2.8, “Interrupts”).
2.5.2
Stop Mode
If a command is active (CCIF = 0) when the MCU enters stop mode, the operation will be aborted and, if
the operation is program or erase, the Flash array data being programmed or erased may be corrupted and
the CCIF and ACCERR flags will be set. If active, the high voltage circuitry to the Flash memory will
immediately be switched off when entering stop mode. Upon exit from stop mode, the CBEIF flag is set
and any buffered command will not be launched. The ACCERR flag must be cleared before starting a
command write sequence (see Section 2.4.1.2, “Command Write Sequence”).
NOTE
As active commands are immediately aborted when the MCU enters stop
mode, it is strongly recommended that the user does not use the STOP
instruction during program or erase operations.
2.5.3
Background Debug Mode
In background debug mode (BDM), the FPROT register is writable. If the MCU is unsecured, then all
Flash commands listed in Table 2-20 can be executed.
2.6
Flash Module Security
The Flash module provides the necessary security information to the MCU. After each reset, the Flash
module determines the security state of the MCU as defined in Section 2.3.2.2, “Flash Security Register
(FSEC)”.
The contents of the Flash security byte at 0xFF0F in the Flash configuration field must be changed directly
by programming 0xFF0F when the MCU is unsecured and the higher address sector is unprotected. If the
Flash security byte remains in a secured state, any reset will cause the MCU to initialize to a secure
operating mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
91
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
2.6.1
Unsecuring the MCU using Backdoor Key Access
The MCU may be unsecured by using the backdoor key access feature which requires knowledge of the
contents of the backdoor keys (four 16-bit words programmed at addresses 0xFF00–0xFF07). If the
KEYEN[1:0] bits are in the enabled state (see Section 2.3.2.2, “Flash Security Register (FSEC)”) and the
KEYACC bit is set, a write to a backdoor key address in the Flash memory triggers a comparison between
the written data and the backdoor key data stored in the Flash memory. If all four words of data are written
to the correct addresses in the correct order and the data matches the backdoor keys stored in the Flash
memory, the MCU will be unsecured. The data must be written to the backdoor keys sequentially starting
with 0xFF00–0xFF01 and ending with 0xFF06–0xFF07. 0x0000 and 0xFFFF are not permitted as
backdoor keys. While the KEYACC bit is set, reads of the Flash memory will return invalid data.
The user code stored in the Flash memory must have a method of receiving the backdoor key from an
external stimulus. This external stimulus would typically be through one of the on-chip serial ports.
If the KEYEN[1:0] bits are in the enabled state (see Section 2.3.2.2, “Flash Security Register (FSEC)”),
the MCU can be unsecured by the backdoor access sequence described below:
1. Set the KEYACC bit in the Flash configuration register (FCNFG).
2. Write the correct four 16-bit words to Flash addresses 0xFF00–0xFF07 sequentially starting with
0xFF00.
3. Clear the KEYACC bit.
4. If all four 16-bit words match the backdoor keys stored in Flash addresses 0xFF00–0xFF07, the
MCU is unsecured and the SEC[1:0] bits in the FSEC register are forced to the unsecure state of
1:0.
The backdoor key access sequence is monitored by an internal security state machine. An illegal operation
during the backdoor key access sequence will cause the security state machine to lock, leaving the MCU
in the secured state. A reset of the MCU will cause the security state machine to exit the lock state and
allow a new backdoor key access sequence to be attempted. The following operations during the backdoor
key access sequence will lock the security state machine:
1. If any of the four 16-bit words does not match the backdoor keys programmed in the Flash array.
2. If the four 16-bit words are written in the wrong sequence.
3. If more than four 16-bit words are written.
4. If any of the four 16-bit words written are 0x0000 or 0xFFFF.
5. If the KEYACC bit does not remain set while the four 16-bit words are written.
6. If any two of the four 16-bit words are written on successive MCU clock cycles.
After the backdoor keys have been correctly matched, the MCU will be unsecured. After the MCU is
unsecured, the Flash security byte can be programmed to the unsecure state, if desired.
In the unsecure state, the user has full control of the contents of the backdoor keys by programming
addresses 0xFF00–0xFF07 in the Flash configuration field.
The security as defined in the Flash security byte (0xFF0F) is not changed by using the backdoor key
access sequence to unsecure. The backdoor keys stored in addresses 0xFF00–0xFF07 are unaffected by
the backdoor key access sequence. After the next reset of the MCU, the security state of the Flash module
MC9S12HZ256 Data Sheet, Rev. 2.04
92
Freescale Semiconductor
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
is determined by the Flash security byte (0xFF0F). The backdoor key access sequence has no effect on the
program and erase protections defined in the Flash protection register.
It is not possible to unsecure the MCU in special single-chip mode by using the backdoor key access
sequence via the background debug mode (BDM).
2.6.2
Unsecuring the Flash Module in Special Single-Chip Mode using
BDM
The MCU can be unsecured in special single-chip mode by erasing the Flash module by the following
method :
• Reset the MCU into special single-chip mode, delay while the erase test is performed by the BDM
secure ROM, send BDM commands to disable protection in the Flash module, and execute a mass
erase command write sequence to erase the Flash memory.
After the CCIF flag sets to indicate that the mass operation has completed, reset the MCU into special
single-chip mode. The BDM secure ROM will verify that the Flash memory is erased and will assert the
UNSEC bit in the BDM status register. This BDM action will cause the MCU to override the Flash security
state and the MCU will be unsecured. All BDM commands will be enabled and the Flash security byte
may be programmed to the unsecure state by the following method:
• Send BDM commands to execute a word program sequence to program the Flash security byte to
the unsecured state and reset the MCU.
2.7
2.7.1
Resets
Flash Reset Sequence
On each reset, the Flash module executes a reset sequence to hold CPU activity while loading the following
registers from the Flash memory according to Table 2-1:
• FPROT — Flash Protection Register (see Section 2.3.2.5).
• FCTL — Flash Control Register (see Section 2.3.2.9).
• FSEC — Flash Security Register (see Section 2.3.2.2).
2.7.2
Reset While Flash Command Active
If a reset occurs while any Flash command is in progress, that command will be immediately aborted. The
state of the word being programmed or the sector / block being erased is not guaranteed.
2.8
Interrupts
The Flash module can generate an interrupt when all Flash command operations have completed, when the
Flash address, data, and command buffers are empty.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
93
Chapter 2 256 Kbyte Flash Module (FTS256K2V1)
Table 2-21. Flash Interrupt Sources
Interrupt Source
Interrupt Flag
Flash address, data and command buffers empty
All Flash commands completed
Local Enable
Global (CCR) Mask
CBEIF (FSTAT register) CBEIE (FCNFG register)
CCIF (FSTAT register)
CCIE (FCNFG register)
I Bit
I Bit
NOTE
Vector addresses and their relative interrupt priority are determined at the
MCU level.
2.8.1
Description of Flash Interrupt Operation
The logic used for generating interrupts is shown in Figure 2-29.
The Flash module uses the CBEIF and CCIF flags in combination with the CBIE and CCIE enable bits to
generate the Flash command interrupt request.
Block 0 CBEIF
Block 0 Select
Block 1 CBEIF
Block 1 Select
CBEIE
Flash Command
Interrupt Request
Block 0 CCIF
Block 0 Select
Block 1 CCIF
Block 1 Select
CCIE
Figure 2-29. Flash Interrupt Implementation
For a detailed description of the register bits, refer to Section 2.3.2.4, “Flash Configuration Register
(FCNFG)” and Section 2.3.2.7, “Flash Status Register (FSTAT)”.
MC9S12HZ256 Data Sheet, Rev. 2.04
94
Freescale Semiconductor
Chapter 3
2 Kbyte EEPROM Module (EETS2KV1)
3.1
Introduction
This document describes the EETS2K module which is a 2 Kbyte EEPROM (nonvolatile) memory. The
EETS2K block uses a small sector Flash memory to emulate EEPROM functionality. It is an array of
electrically erasable and programmable, nonvolatile memory. The EEPROM memory is organized as 1024
rows of 2 bytes (1 word). The EEPROM memory’s erase sector size is 2 rows or 2 words (4 bytes).
The EEPROM memory may be read as either bytes, aligned words, or misaligned words. Read access time
is one bus cycle for byte and aligned word, and two bus cycles for misaligned words.
Program and erase functions are controlled by a command driven interface. Both sector erase and mass
erase of the entire EEPROM memory are supported. An erased bit reads 1 and a programmed bit reads 0.
The high voltage required to program and erase is generated internally by on-chip charge pumps.
It is not possible to read from the EEPROM memory while it is being erased or programmed.
The EEPROM memory is ideal for data storage for single-supply applications allowing for field
reprogramming without requiring external programming voltage sources.
CAUTION
An EEPROM word must be in the erased state before being programmed.
Cumulative programming of bits within a word is not allowed.
3.1.1
Glossary
Command Write Sequence — A three-step MCU instruction sequence to program, erase, or erase verify
the EEPROM.
3.1.2
•
•
•
•
•
•
•
•
Features
2 Kbytes of EEPROM memory
Minimum erase sector of 4 bytes
Automated program and erase algorithms
Interrupts on EEPROM command completion and command buffer empty
Fast sector erase and word program operation
2-stage command pipeline
Flexible protection scheme for protection against accidental program or erase
Single power supply program and erase
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
95
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
3.1.3
Modes of Operation
Program and erase operation (please refer to Section 3.4.1 for details).
3.1.4
Block Diagram
Figure 3-1 shows a block diagram of the EETS2K module.
EETS2K
Command
Interface
Registers
Command Pipeline
comm2
addr2
data2
EEPROM Array
1024 * 16 Bits
row0
row1
row1023
comm1
addr1
data1
Command
Complete
Interrupt
Command
Buffer Empty
Interrupt
Oscillator
Clock
Clock
Divider
EECLK
Figure 3-1. EETS2K Block Diagram
3.2
External Signal Description
The EETS2K module contains no signals that connect off chip.
3.3
Memory Map and Register Definition
This section describes the EETS2K memory map and registers.
3.3.1
Module Memory Map
Figure 3-2 shows the EETS2K memory map. Location of the EEPROM array in the MCU memory map
is defined in the Device Overview chapter and is reflected in the INITEE register contents defined in the
INT block description chapter. Shown within the EEPROM array are: a protection/reserved field and
user-defined EEPROM protected sectors. The 16-byte protection/reserved field is located in the EEPROM
array from address 0x07F0 to 0x07FF. A description of this protection/reserved field is given in Table 3-1.
MC9S12HZ256 Data Sheet, Rev. 2.04
96
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
Table 3-1. EEPROM Protection/Reserved Field
Address Offset
Size
(Bytes)
Description
0x07F0 – 0x07FC
13
Reserved
0x07FD
1
EEPROM protection byte
0x07FE – 0x07FF
2
Reserved
The EEPROM module has hardware interlocks which protect data from accidental corruption. A protected
sector is located at the higher address end of the EEPROM array, just below address 0x07FF. The protected
sector in the EEPROM array can be sized from 64 bytes to 512 bytes. In addition, the EPOPEN bit in the
EPROT register, described in Section 3.3.2.5, “EEPROM Protection Register (EPROT)”, can be set to
globally protect the entire EEPROM array.
Chip security is defined at the MCU level.
(12 BYTES)
MODULE BASE + 0x0000
EEPROM Registers
MODULE BASE + 0x000B
EEPROM BASE + 0x0000
1536 BYTES
EEPROM ARRAY
0x0600
0x0640
0x0680
0x06C0
0x0700
EEPROM Protected High Sectors
64, 128, 192, 256, 320, 384, 448, 512 bytes
0x0740
0x0780
0x07C0
EEPROM BASE + 0x07FF
0x07F0 – 0x07FF, EEPROM Protection/Reserved Field
Figure 3-2. EEPROM Memory Map
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
97
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
The EEPROM module also contains a set of 12 control and status registers located in address space module
base + 0x0000 to module base + 0x000B.
Table 3-2 gives an overview of all EETS2K registers.
Table 3-2. EEPROM Register Map
Module
Base +
0x0000
1
Register Name
EEPROM Clock Divider Register (ECLKDIV)
Normal Mode
Access
R/W
0x0001
1
RESERVED1
R
0x0002
RESERVED21
R
0x0003
EEPROM Configuration Register (ECNFG)
R/W
0x0004
EEPROM Protection Register (EPROT)
R/W
0x0005
EEPROM Status Register (ESTAT)
R/W
0x0006
EEPROM Command Register (ECMD)
R/W
0x0007
RESERVED31
0x0008
EEPROM High Address Register (EADDRHI)
R
R/W
0x0009
EEPROM Low Address Register (EADDRLO)
R/W
0x000A
EEPROM High Data Register (EDATAHI)
R/W
0x000B
EEPROM Low Data Register (EDATALO)
R/W
Intended for factory test purposes only.
MC9S12HZ256 Data Sheet, Rev. 2.04
98
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
3.3.2
Register Descriptions
Register
Name
Bit 7
ECLKDIV
R
6
5
4
3
2
1
Bit 0
PRDIV8
EDIV5
EDIV4
EDIV3
EDIV2
EDIV1
EDIV0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CBEIE
CCIE
0
0
0
0
0
0
NV5
NV4
EPDIS
EP2
EP1
EPO
PVIOL
ACCERR
0
BLANK
0
0
EDIVLD
W
RESERVED1
R
W
RESERVED2
R
W
ECNFG
R
W
EPROT
R
W
ESTAT
R
W
ECMD
R
EPOPEN
CBEIF
0
R
CCIF
0
0
0
0
0
0
0
0
0
0
CMDB6
CMDB5
0
0
0
0
W
RESERVED3
NV6
CMDB2
0
CMDB0
0
0
W
EADDRHI
R
W
EADDRLO
R
EABLO
W
EDATAHI
R
EDHI
W
EDATALO
EABHI
R
EDLO
W
= Unimplemented or Reserved
Figure 3-3. EETS2K Register Summary
3.3.2.1
EEPROM Clock Divider Register (ECLKDIV)
The ECLKDIV register is used to control timed events in program and erase algorithms.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
99
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
7
R
6
5
4
3
2
1
0
PRDIV8
EDIV5
EDIV4
EDIV3
EDIV2
EDIV1
EDIV0
0
0
0
0
0
0
0
EDIVLD
W
Reset
0
= Unimplemented or Reserved
Figure 3-4. EEPROM Clock Divider Register (ECLKDIV)
All bits in the ECLKDIV register are readable while bits 6-0 are write once and bit 7 is not writable.
Table 3-3. ECLKDIV Field Descriptions
Field
Description
7
EDIVLD
Clock Divider Loaded
0 Register has not been written.
1 Register has been written to since the last reset.
6
PRDIV8
Enable Prescaler by 8
0 The oscillator clock is directly fed into the ECLKDIV divider.
1 The oscillator clock is divided by 8 before feeding into the clock divider.
5:0
EDIV[5:0]
3.3.2.2
Clock Divider Bits — The combination of PRDIV8 and EDIV[5:0] must divide the oscillator clock down to a
frequency of 150 kHz – 200 kHz. The maximum divide ratio is 512. Please refer to Section 3.4.1.1, “Writing the
ECLKDIV Register” for more information.
RESERVED1
This register is reserved for factory testing and is not accessible to the user.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 3-5. RESERVED1
All bits read 0 and are not writable.
3.3.2.3
RESERVED2
This register is reserved for factory testing and is not accessible to the user.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 3-6. RESERVED2
MC9S12HZ256 Data Sheet, Rev. 2.04
100
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
All bits read 0 and are not writable.
3.3.2.4
EEPROM Configuration Register (ECNFG)
The ECNFG register enables the EEPROM interrupts.
7
6
CBEIE
CCIE
0
0
R
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 3-7. EEPROM Configuration Register (ECNFG)
CBEIE and CCIE bits are readable and writable while bits 5-0 read 0 and are not writable.
Table 3-4. ECNFG Field Descriptions
Field
Description
7
CBEIE
Command Buffer Empty Interrupt Enable — The CBEIE bit enables the interrupts in case of an empty
command buffer in the EEPROM.
0 Command buffer empty interrupts disabled.
1 An interrupt will be requested whenever the CBEIF flag is set (see Section 3.3.2.6, “EEPROM Status Register
(ESTAT)”).
6
CCIE
Command Complete Interrupt Enable — The CCIE bit enables the interrupts in case of all commands being
completed in the EEPROM.
0 Command complete interrupts disabled.
1 An interrupt will be requested whenever the CCIF flag is set (see Section 3.3.2.6, “EEPROM Status Register
(ESTAT)”).
3.3.2.5
EEPROM Protection Register (EPROT)
The EPROT register defines which EEPROM sectors are protected against program or erase.
7
R
6
5
4
NV6
NV5
NV4
EPOPEN
3
2
1
0
EPDIS
EP2
EP1
EP0
F
F
F
F
W
Reset
F
F
F
F
= Unimplemented or Reserved
Figure 3-8. EEPROM Protection Register (EPROT)
The EPROT register is loaded from EEPROM array address 0x07FD during reset, as indicated by the F in
Figure 3-8.
All bits in the EPROT register are readable. Bits NV[6:4] are not writable. The EPOPEN and EPDIS bits
in the EPROT register can only be written to the protected state (i.e., 0). The EP[2:0] bits can be written
anytime until bit EPDIS is cleared. If the EPOPEN bit is cleared, then the state of the EPDIS and EP[2:0]
bits is irrelevant.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
101
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
To change the EEPROM protection that will be loaded on reset, the upper sector of EEPROM must first
be unprotected, then the EEPROM protect byte located at address 0x07FD must be written to.
A protected EEPROM sector is disabled by the EPDIS bit while the size of the protected sector is defined
by the EP bits in the EPROT register.
Trying to alter any of the protected areas will result in a protect violation error and PVIOL flag will be set
in the ESTAT register. A mass erase of a whole EEPROM block is only possible when protection is fully
disabled by setting the EPOPEN and EPDIS bits. An attempt to mass erase an EEPROM block while
protection is enabled will set the PVIOL flag in the ESTAT register.
Table 3-5. EPROT Field Descriptions
Field
Description
7
EPOPEN
Opens EEPROM for Program or Erase
0 The whole EEPROM array is protected. In this case, the EPDIS and EP bits within the protection register are
ignored.
1 The EEPROM sectors not protected are enabled for program or erase.
6:4
NV[6:4]
Nonvolatile Flag Bits — These three bits are available to the user as nonvolatile flags.
3
EPDIS
EEPROM Protection Address Range Disable — The EPDIS bit determines whether there is a protected area
in the space of the EEPROM address map.
0 Protection enabled
1 Protection disabled
2:0
EP[2:0]
EEPROM Protection Address Size — The EP[2:0] bits determine the size of the protected sector. Refer to
Table 3-6.
Table 3-6. EEPROM Address Range Protection
3.3.2.6
EP[2:0]
Protected
Address Range
Protected Size
000
0x07C0-0x07FF
64 bytes
001
0x0780-0x07FF
128 bytes
010
0x0740-0x07FF
192 bytes
011
0x0700-0x07FF
256 bytes
100
0x06C0-0x07FF
320 bytes
101
0x0680-0x07FF
384 bytes
110
0x0640-0x07FF
448 bytes
111
0x0600-0x07FF
512 bytes
EEPROM Status Register (ESTAT)
The ESTAT register defines the EEPROM state machine command status and EEPROM array access,
protection and erase verify status.
MC9S12HZ256 Data Sheet, Rev. 2.04
102
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
7
6
R
5
4
PVIOL
ACCERR
0
0
CCIF
CBEIF
3
2
1
0
0
BLANK
0
0
0
0
0
0
1
0
W
Reset
1
1
= Unimplemented or Reserved
Figure 3-9. EEPROM Status Register (ESTAT - Normal Mode)
7
6
R
5
4
PVIOL
ACCERR
0
0
CCIF
CBEIF
3
2
0
BLANK
DONE
FAIL
W
Reset
1
1
0
0
0
1
= Unimplemented or Reserved
Figure 3-10. EEPROM Status Register (ESTAT - Special Mode)
CBEIF, PVIOL, and ACCERR bits are readable and writable, CCIF and BLANK bits are readable but not
writable, remaining bits read 0 and are not writable in normal mode. FAIL is readable and writable in
special mode. FAIL must be clear when starting a command write sequence. DONE is readable but not
writable in special mode.
Table 3-7. ESTAT Field Descriptions
Field
Description
7
CBEIF
Command Buffer Empty Interrupt Flag — The CBEIF flag indicates that the address, data, and command
buffers are empty so that a new command sequence can be started. The CBEIF flag is cleared by writing a 1 to
CBEIF. Writing a 0 to the CBEIF flag has no effect on CBEIF. Writing a 0 to CBEIF after writing an aligned word
to the EEPROM address space but before CBEIF is cleared will abort a command sequence and cause the
ACCERR flag in the ESTAT register to be set. Writing a 0 to CBEIF outside of a command sequence will not set
the ACCERR flag. The CBEIF flag is used together with the CBEIE bit in the ECNFG register to generate an
interrupt request.
0 Buffers are full
1 Buffers are ready to accept a new command
6
CCIF
Command Complete Interrupt Flag — The CCIF flag indicates that there are no more commands pending. The
CCIF flag is cleared when CBEIF is cleared and sets automatically upon completion of all active and pending
commands. The CCIF flag does not set when an active command completes and a pending command is fetched
from the command buffer. Writing to the CCIF flag has no effect. The CCIF flag is used together with the CCIE
bit in the ECNFG register to generate an interrupt request.
0 Command in progress
1 All commands are completed
5
PVIOL
Protection Violation — The PVIOL flag indicates an attempt was made to program or erase an address in a
protected EEPROM memory area (Section 3.4.1.4, “Illegal EEPROM Operations”). The PVIOL flag is cleared by
writing a 1 to PVIOL. Writing a 0 to the PVIOL flag has no effect on PVIOL. While PVIOL is set, it is not possible
to launch another command in the EEPROM.
0 No failure
1 A protection violation has occurred
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
103
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
Table 3-7. ESTAT Field Descriptions (continued)
Field
Description
4
ACCERR
EEPROM Access Error — The ACCERR flag indicates an illegal access to the selected EEPROM array
(Section 3.4.1.4, “Illegal EEPROM Operations). This can be either a violation of the command sequence, issuing
an illegal command (illegal combination of the CMDBx bits in the ECMD register) or the execution of a CPU
STOP instruction while a command is executing (CCIF = 0). The ACCERR flag is cleared by writing a 1 to
ACCERR. Writing a 0 to the ACCERR flag has no effect on ACCERR. While ACCERR is set, it is not possible to
launch another command in the EEPROM.
0 No failure
1 Access error has occurred
2
BLANK
Array Has Been Verified as Erased — The BLANK flag indicates that an erase verify command has checked
the EEPROM array and found it to be erased. The BLANK flag is cleared by hardware when CBEIF is cleared
as part of a new valid command sequence. Writing to the BLANK flag has no effect on BLANK.
0 If an erase verify command has been requested and the CCIF flag is set, then a 0 in BLANK indicates array
is not erased
1 EEPROM array verifies as erased
1
FAIL
Flag Indicating a Failed EEPROM Operation — The FAIL flag will set if the erase verify operation fails
(EEPROM block verified as not erased). The FAIL flag is cleared writing a 1 to FAIL. Writing a 0 to the FAIL flag
has no effect on FAIL.
0 EEPROM operation completed without error
1 EEPROM operation failed
0
DONE
3.3.2.7
Flag Indicating a Completed EEPROM Operation
0 EEPROM operation is active (program, erase, erase verify)
1 EEPROM operation not active
EEPROM Command Register (ECMD)
The ECMD register defines the EEPROM commands.
7
R
6
5
CMDB6
CMDB5
0
0
0
4
3
0
0
2
1
0
0
CMDB2
CMDB0
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 3-11. EEPROM Command Register (ECMD)
CMDB6, CMDB5, CMDB2, and CMDB0 bits are readable and writable during a command sequence
while bits 7, 4, 3, and 1 read 0 and are not writable.
Table 3-8. ECMD Field Descriptions
Field
6, 5, 2, 0
CMDB[6:5]
CMDB2
CMDB0
Description
EEPROM Command — Valid EEPROM commands are shown in Table 3-9. Any other command written than
those mentioned in Table 3-9 sets the ACCERR bit in the ESTAT register.
MC9S12HZ256 Data Sheet, Rev. 2.04
104
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
Table 3-9. Valid EEPROM Command List
3.3.2.8
Command
Meaning
0x05
Erase verify
0x20
Word program
0x40
Sector erase
0x41
Mass erase
0x60
Sector modify
RESERVED3
This register is reserved for factory testing and is not accessible to the user.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
W
Reset
= Unimplemented or Reserved
Figure 3-12. RESERVED3
All bits read 0 and are not writable.
3.3.2.9
EEPROM Address Register (EADDR)
EADDRHI and EADDRLO are the EEPROM address registers.
R
7
6
5
4
3
2
0
0
0
0
0
0
EABHI
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 3-13. EEPROM Address High Register (EADDRHI)
7
6
5
4
3
2
1
0
0
0
0
0
R
EABLO
W
Reset
0
0
0
0
Figure 3-14. EEPROM Address Low Register (EADDRLO)
In normal modes, all EADDRHI and EADDRLO bits read 0 and are not writable.
In special modes, all EADDRHI and EADDRLO bits are readable and writable except EADDRHI[7:2]
which are not writable and always read 0.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
105
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
For sector erase, the MCU address bits AB[1:0] are ignored.
For mass erase, any address within the block is valid to start the command.
MC9S12HZ256 Data Sheet, Rev. 2.04
106
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
3.3.2.10
EEPROM Data Register (EDATA)
EDATAHI and EDATALO are the EEPROM data registers.
7
6
5
4
3
2
1
0
0
0
0
0
R
EDHI
W
Reset
0
0
0
0
Figure 3-15. EEPROM Data High Register (EDATAHI)
7
6
5
4
3
2
1
0
0
0
0
0
R
EDLO
W
Reset
0
0
0
0
Figure 3-16. EEPROM Data Low Register (EDATALO)
In normal modes, all EDATAHI and EDATALO bits read 0 and are not writable.
In special modes, all EDATAHI and EDATALO bits are readable and writable.
3.4
3.4.1
Functional Description
Program and Erase Operation
Write and read operations are both used for the program and erase algorithms described in this subsection.
These algorithms are controlled by a state machine whose timebase, EECLK, is derived from the oscillator
clock via a programmable divider. The command register as well as the associated address and data
registers operate as a buffer and a register (2-stage FIFO) so that a new command along with the necessary
data and address can be stored to the buffer while the previous command is remains in progress. The
pipelined operation allows a simplification of command launching. Buffer empty as well as command
completion are signalled by flags in the EEPROM status register. Interrupts for the EEPROM will be
generated if enabled.
The next four subsections describe:
• How to write the ECLKDIV register.
• Command write sequences used to program, erase, and verify the EEPROM memory.
• Valid EEPROM commands.
• Errors resulting from illegal EEPROM operations.
3.4.1.1
Writing the ECLKDIV Register
Prior to issuing any program or erase command, it is first necessary to write the ECLKDIV register to
divide the oscillator down to within 150 kHz to 200 kHz range. The program and erase timings are also a
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
107
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
function of the bus clock, such that the ECLKDIV determination must take this information into account.
If we define:
• EECLK as the clock of the EEPROM timing control block
• Tbus as the period of the bus clock
• INT(x) as taking the integer part of x (e.g., INT(4.323)=4), then ECLKDIV register bits PRDIV8
and EDIV[5:0] are to be set as described in Figure 3-17.
For example, if the oscillator clock is 950 kHz and the bus clock is 10 MHz, ECLKDIV bits EDIV[5:0]
must be set to 4 (binary 000100) and bit PRDIV8 set to 0. The resulting EECLK is then 190 kHz. As a
result, the EEPROM algorithm timings are increased over optimum target by:
( 200 – 190 ) ⁄ 200 × 100 = 5%
Command execution time will increase proportionally with the period of EECLK.
CAUTION
Because of the impact of clock synchronization on the accuracy of the
functional timings, programming or erasing the EEPROM cannot be
performed if the bus clock runs at less than 1 MHz. Programming the
EEPROM with an oscillator clock < 150 kHz must be avoided. Setting
ECLKDIV to a value such that EECLK < 150 kHz can reduce the lifetime
of the EEPROM due to overstress. Setting ECLKDIV to a value such that
(1/EECLK+Tbus) < 5µs can result in incomplete programming or erasure
of the memory array cells.
If the ECLKDIV register is written, the bit EDIVLD is set automatically. If this bit is 0, the register has
not been written since the last reset. EEPROM commands will not be executed if this register has not been
written to.
MC9S12HZ256 Data Sheet, Rev. 2.04
108
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
START
NO
Tbus ≤ 1 µs?
PROGRAM/ERASE IMPOSSIBLE
yes
PRDIV8 = 0 (reset)
OSCILLATOR
CLOCK
> 12.8 MHz?
NO
yes
PRDIV8 = 1
PRDCLK = oscillator clock/8
PRDCLK[MHz]*(5+Tbus[µs])
an integer?
PRDCLK = oscillator clock
NO
EDIV[5:0] = INT(PRDCLK[MHz]*(5+Tbus[µs]))
YES
EDIV[5:0] = PRDCLK[MHz]*(5+Tbus[µs])-1
TRY TO DECREASE Tbus
EECLK = (PRDCLK)/(1+EDIV[5:0])
1/EECLK [MHz] + Tbus[ms] ≥5
AND
EECLK > 0.15 MHz
YES
END
?
NO
YES
EDIV[5:0] ≥ 4?
NO
PROGRAM/ERASE IMPOSSIBLE
Figure 3-17. PRDIV8 and EDIV Bits Determination Procedure
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
109
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
3.4.1.2
Command Write Sequence
The EEPROM command controller is used to supervise the command write sequence to execute program,
erase, mass erase, sector modify, and erase verify operations. Before starting a command write sequence,
it is necessary to check that there is no pending access error or protection violation (the ACCERR and
PVIOL flags must be cleared in the ESTAT register).
After this initial step, the CBEIF flag must be tested to ensure that the address, data and command buffers
are empty. If so, the command sequence can be started. The following 3-step command write sequence
must be strictly adhered to and no intermediate access to the EEPROM array is permitted between the 3
steps. It is possible to read any EEPROM register during a command sequence. The command write
sequence is as follows:
1. Write an aligned word to be to a valid EEPROM array address. The address and data will be stored
in internal buffers.
— For program and sector modify, all address and data bits are valid.
— For erase, the value of the data bytes are ignored.
— For mass erase and erase verify, the address can be anywhere in the available address space of
the array.
— For sector erase, the address bits[1:0] are ignored.
2. Write a valid command, listed in Table 3-10, to the ECMD register.
3. Clear the CBEIF flag by writing a 1 to CBEIF to launch the command. When the CBEIF flag is
cleared, the CCIF flag is cleared by hardware indicating that the command was successfully
launched. The CBEIF flag will be set again indicating the address, data, and command buffers are
ready for a new command write sequence to begin.
The completion of the command is indicated by the CCIF flag setting. The CCIF flag only sets when all
active and pending commands have been completed.
The EEPROM command controller will flag errors in command write sequences by means of the
ACCERR (access error) and PVIOL (protection violation) flags in the ESTAT register. An erroneous
command write sequence will abort and set the appropriate flag. If set, the user must clear the ACCERR
or PVIOL flags before commencing another command write sequence. By writing a 0 to the CBEIF flag
the command sequence can be aborted after the word write to the EEPROM address space or after writing
a command to the ECMD register and before the command is launched. Writing a 0 to the CBEIF flag in
this way will set the ACCERR flag.
A summary of the launching of a program operation is shown in Figure 3-18. For other operations, the user
writes the appropriate command to the ECMD register.
MC9S12HZ256 Data Sheet, Rev. 2.04
110
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
Read: Register ECLKDIV
Clock Register
Written
Check
Bit EDIVLD set?
yes
no
Write: Register ECLKDIV
1.
Write: Array Address and
Program Data
2.
Write: Register ECMD
Program Command 0x20
NOTE: command sequence
aborted by writing 0x00 to
ESTAT register.
3.
Write: Register ESTAT
Clear bit CBEIF 0x80
NOTE: command sequence
aborted by writing 0x00 to
ESTAT register.
Read: Register ESTAT
Bit
PVIOL
Set?
Protection
Violation Check
yes Write: Register ESTAT
Clear bit PVIOL 0x20
no
Bit
ACCERR
Set?
Access
Error Check
yes Write: Register ESTAT
Clear bit ACCERR 0x10
yes
no
Address, Data,
Command
Buffer Empty Check
Bit
CBEIF
Set?
yes
Next Write?
no
no
Bit Polling for
Command
Completion Check
Bit
CCIF
Set?
no
Read: Register ESTAT
yes
EXIT
Figure 3-18. Example Program Command Flow
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
111
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
3.4.1.3
Valid EEPROM Commands
Table 3-10 summarizes the valid EEPROM commands. Also shown are the effects of the commands on
the EEPROM array.
Table 3-10. Valid EEPROM Commands
ECMD
Meaning
Function on EEPROM Array
0x05
Erase Verify
Verify all memory bytes of the EEPROM array are erased. If the array is erased, the BLANK bit
will set in the ESTAT register upon command completion.
0x20
Program
0x40
Sector Erase
Erase two words (four bytes) of EEPROM array.
0x41
Mass Erase
Erase all of the EEPROM array. A mass erase of the full array is only possible when EPDIS and
EPOPEN are set.
0x60
Sector Modify
Program a word (two bytes).
Erase two words of EEPROM, re-program one word.
CAUTION
An EEPROM word must be in an erased state before being programmed.
Cumulative programming of bits within a word is not allowed.
The sector modify command (0x60) is a two-step command which first erases a sector (2 words) of the
EEPROM array and then re-programs one of the words in that sector. The EEPROM sector which is erased
by the sector modify command is the sector containing the address of the aligned array write which starts
the valid command sequence. That same address is re-programmed with the data which is written. By
launching a sector modify command and then pipelining a program command it is possible to completely
replace the contents of an EEPROM sector.
3.4.1.4
Illegal EEPROM Operations
The ACCERR flag will be set during the command write sequence if any of the following illegal
operations are performed causing the command write sequence to immediately abort:
1. Writing to the EEPROM address space before initializing ECLKDIV.
2. Writing a misaligned word or a byte to the valid EEPROM address space.
3. Writing to the EEPROM address space while CBEIF is not set.
4. Writing a second word to the EEPROM address space before executing a program or erase
command on the previously written word.
5. Writing to any EEPROM register other than ECMD after writing a word to the EEPROM address
space.
6. Writing a second command to the ECMD register before executing the previously written
command.
7. Writing an invalid command to the ECMD register in normal mode.
8. Writing to any EEPROM register other than ESTAT (to clear CBEIF) after writing to the command
register (ECMD).
MC9S12HZ256 Data Sheet, Rev. 2.04
112
Freescale Semiconductor
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
9. The part enters stop mode and a program or erase command is in progress. The command is aborted
and any pending command is killed.
10. A 0 is written to the CBEIF bit in the ESTAT register.
The ACCERR flag will not be set if any EEPROM register is read during the command sequence.
If the EEPROM array is read during execution of an algorithm (i.e., CCIF bit in the ESTAT register is
low), the read will return non-valid data and the ACCERR flag will not be set.
When an ACCERR flag is set in the ESTAT register, the command state machine is locked. It is not
possible to launch another command until the ACCERR flag is cleared.
The PVIOL flag will be set during the command write sequence after the word write to the EEPROM
address space and the command sequence will be aborted if any of the following illegal operations are
performed.
1. Writing a EEPROM address to program in a protected area of the EEPROM.
2. Writing a EEPROM address to erase in a protected area of the EEPROM.
3. Writing the mass erase command to ECMD while any protection is enabled.
When the PVIOL flag is set in the ESTAT register the command state machine is locked. It is not possible
to launch another command until the PVIOL flag is cleared.
3.5
3.5.1
Operating Modes
Wait Mode
If an EEPROM command is active (CCIF = 0) when the MCU enters wait mode, that command and any
pending command will be completed.
The EETS2K module can recover the MCU from wait mode if the interrupts are enabled (see Section 3.7,
“Interrupts”).
3.5.2
Stop Mode
If a command is active (CCIF = 0) when the MCU enters stop mode, the operation will be aborted and if
the operation is program, erase, or sector modify, the data being programmed or erased may be corrupted
and the CCIF and ACCERR flags will be set. If active, the high voltage circuitry to the EEPROM array
will be switched off when entering stop mode. Upon exit from stop mode, the CBEIF flag is set and any
pending command will not be launched. The ACCERR flag must be cleared before starting a new
command write sequence.
NOTE
As active commands are immediately aborted when the MCU enters stop
mode, it is strongly recommended that the user does not use the STOP
instruction during program, erase, or sector modify operations.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
113
Chapter 3 2 Kbyte EEPROM Module (EETS2KV1)
3.5.3
Background Debug Mode
In background debug mode (BDM), the EPROT register is writable. If the chip is unsecured then all
EEPROM commands listed in Table 3-10 can be executed. If the chip is secured in special single-chip
mode, then the only possible command to execute is mass erase.
3.6
Resets
If a reset occurs while any EEPROM command is in progress, that command will be immediately aborted.
The state of the word being programmed or the sector / block being erased is not guaranteed.
3.7
Interrupts
The EEPROM module can generate an interrupt when all EEPROM commands are completed or the
address, data, and command buffers are empty.
Table 3-11. EEPROM Interrupt Sources
Interrupt Source
Interrupt Flag
Local Enable
Global (CCR) Mask
EEPROM address, data and
command buffers empty
CBEIF
(ESTAT register)
CBEIE
I Bit
All commands are completed
on EEPROM
CCIF
(ESTAT register)
CCIE
I Bit
NOTE
Vector addresses and their relative interrupt priority are determined at the
MCU level.
For a detailed description of the register bits, refer to Section 3.3.2.4, “EEPROM Configuration Register
(ECNFG)” and Section 3.3.2.6, “EEPROM Status Register (ESTAT)”.
MC9S12HZ256 Data Sheet, Rev. 2.04
114
Freescale Semiconductor
Chapter 4
Port Integration Module (PIM9HZ256V2)
4.1
lntroduction
The port integration module establishes the interface between the peripheral modules and the I/O pins for
for ports AD, L, M, P, T, U and V.
This section covers:
• Port A, B, E, and K and the BKGD pin, which are shared between the core logic (including
multiplexed bus interface) and the LCD driver
• Port AD associated with ATD module (channels 7 through 0) and keyboard wake-up interrupts
• Port L connected to the LCD driver and ATD (channels 15 through 8) modules
• Port M connected to 2 CAN modules
• Port P connected to 1 SCI, 1 IIC and PWM modules
• Port S connected to 1 SCI and 1 SPI modules
• Port T connected to the timer module (TIM) and the LCD driver
• Port U and V associated with PWM motor control and stepper stall detect modules
Each I/O pin can be configured by several registers: input/output selection, drive strength reduction,
enable and select of pull resistors, wired-or mode selection, interrupt enable, and/or status flags.
NOTE
Ports A, B, E and K, and the BKGD pin are shared between core logic
(including multiplexed bus interface) and the LCD driver. Refer to the
MEBI block description chapter for details on these ports.
4.1.1
Features
A standard port has the following minimum features:
• Input/output selection
• 5-V output drive with two selectable drive strength (or slew rates)
• 5-V digital and analog input
• Input with selectable pull-up or pull-down device
Optional features:
•
•
Open drain for wired-OR connections
Interrupt input with glitch filtering
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
115
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.1.2
Block Diagram
Figure 4-1 is a block diagram of the PIM9HZ256.
Port S
Port M
PM2
PM3
PM4
PM5
M0SINM
SSD1
M0SINP
M1COSM
M2COSM
M3COSM
M1COSP
M1SINM
M1SINP
M2COSP
M2SINM
M2SINP
M3COSP
M3SINM
M3SINP
M0C0M
M0C0P
M0C1M
M0C1P
M1C0M
M1C0P
M1C1M
M1C1P
Port U
M0COSP
PWM Motor Controller
SSD0
M0COSM
M2C0M
M2C0P
M2C1M
M2C1P
M3C0M
M3C0P
M3C1M
M3C1P
KWAD0
KWAD1
KWAD2
KWAD3
KWAD4
KWAD5
KWAD6
KWAD7
PV0
PV1
PV2
PV3
PV4
PV5
PV6
PV7
PAD0
PAD1
PAD2
PAD3
PAD4
PAD5
PAD6
PAD7
Timer
(TIM)
ATD
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
PU0
PU1
PU2
PU3
PU4
PU5
PU6
PU7
Port V
CAN1
TXD
PWM
PWM0
PWM1
PWM2
PWM3
PWM4
PWM5
RXCAN
TXCAN
RXCAN
TXCAN
CAN0
AN8
AN9
AN10
AN11
AN12
AN13
AN14
AN15
IOC0
IOC1
IOC2
IOC3
IOC4
IOC5
IOC6
IOC7
PS0
PS1
PS4
PS5
PS6
PS7
Port AD
SPI
SSD2
FP22
BP0
BP1
BP2
BP3
FP23
FP16
FP17
FP18
FP19
FP28
FP29
FP30
FP31
FP24
FP25
FP26
FP27
RXD
TXD
SPI/MISO
SPO/MOSI
SCK
SS
SCI0
SSD3
FP20
FP21
ADDR0
ADDR1
ADDR2
ADDR3
ADDR4
ADDR5
ADDR6
ADDR7
ADDR8
ADDR9
ADDR10
ADDR11
ADDR12
ADDR13
ADDR14
ADDR15
XIRQ
IRQ
R/W
LSTRB/TAGLO
ECLK
IPIPE0/MODA
IPIPE1/MODB
NOACC/XCLKS
XADDR14
XADDR15
XADDR16
XADDR17
ECS/ROMONE
Core
LCD Driver
Port B
Port A
Port K
Port E
FP8
FP9
FP10
FP11
FP12
FP13
FP14
FP15
Port L
PL0
PL1
PL2
PL3
PL4
PL5
PL6
PL7
PT0
PT1
PT2
PT3
PT4
PT5
PT6
PT7
PP0
PP1
PP2
PP3
PP4
PP5
BKGD/MODC/TAGHI
FP0
FP1
FP2
FP3
FP4
FP5
FP6
FP7
Port T
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
PA0
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PE0
PE1
PE2
PE3
PE4
PE5
PE6
PE7
PK0
PK1
PK2
PK3
PK7
Port P
BKGD
BKGD
Port Integration Module
RXD
SDA
SCL
SCI1
IIC
Figure 4-1. PIM9HZ256 Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
116
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.2
External Signal Description
This section lists and describes the signals that connect off chip.
Table 4-1 shows all the pins and their functions that are controlled by the PIM9HZ256. The order in which
the pin functions are listed represents the functions priority (top – highest priority, bottom – lowest
priority).
Table 4-1. Detailed Signal Descriptions (Sheet 1 of 6)
Port
—
Port K
Port E
Pin
Name
Pin Function
BKGD MODC
BKGD
TAGHI
PK7 ECS/ROMONE
FP23
GPIO
PK3 XADDR17
BP3
GPIO
PK2 XADDR16
BP2
GPIO
PK1 XADDR15
BP1
GPIO
PK0 XADDR14
BP0
GPIO
PE7 XCLKS
NOACC
FP22
GPIO
PE6 IPIPE1/MODB
GPIO
PE5 IPIPE0/MODA
GPIO
PE4 ECLK
GPIO
PE3 LSTRB/TAGLO
FP21
GPIO
PE2 FP20
R/W/GPIO
PE1 IRQ
GPIO
PE0 XIRQ
GPIO
Description
Refer to the MEBI block description chapter
Refer to the BDM block description chapter
Refer to the MEBI block description chapter
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to OSC block description chapter
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
General-purpose I/O
Refer to the MEBI block description chapter
General-purpose I/O
Refer to the MEBI block description chapter
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
LCD driver interface
Refer to the MEBI block description chapter
Refer to the MEBI block description chapter
General-purpose I/O
Refer to the MEBI block description chapter
General-purpose I/O
Pin Function
after Reset
Refer to the MEBI block
description chapter
Refer to the MEBI block
description chapter
Refer to the MEBI block
description chapter
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
117
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-1. Detailed Signal Descriptions (Sheet 2 of 6)
Port
Pin
Name
Port A
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
Port B
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
Pin Function
ADDR15/DATA15
FP15
GPIO
ADDR14/DATA14
FP14
GPIO
ADDR13/DATA13
FP13
GPIO
ADDR12/DATA12
FP12
GPIO
ADDR11/DATA11
FP11
GPIO
ADDR10/DATA10
FP10
GPIO
ADDR9/DATA9
FP9
GPIO
ADDR8/DATA8
FP8
GPIO
ADDR7/DATA7
FP7
GPIO
ADDR6/DATA6
FP6
GPIO
ADDR5/DATA5
FP5
GPIO
ADDR4/DATA4
FP4
GPIO
ADDR3/DATA3
FP3
GPIO
ADDR2/DATA2
FP2
GPIO
ADDR1/DATA1
FP1
GPIO
ADDR0/DATA0
FP0
GPIO
Description
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Refer to the MEBI block description chapter
LCD driver interface
General-purpose I/O
Pin Function
after Reset
Refer to the MEBI block
description chapter
Refer to the MEBI block
description chapter
MC9S12HZ256 Data Sheet, Rev. 2.04
118
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-1. Detailed Signal Descriptions (Sheet 3 of 6)
Port
Pin
Name
Port AD
PAD7
PAD6
PAD5
PAD4
PAD3
PAD2
PAD1
PAD0
Port L
PL7
PL6
PL5
PL4
PL3
PL2
PL1
PL0
Pin Function
AN7
KWAD7
GPIO
AN6
KWAD6
GPIO
AN5
KWAD5
GPIO
AN4
KWAD4
GPIO
AN3
KWAD3
GPIO
AN2
KWAD2
GPIO
AN1
KWAD1
GPIO
AN0
KWAD0
GPIO
FP31
AN15
GPIO
FP30
AN14
GPIO
FP29
AN13
GPIO
FP28
AN12
GPIO
FP19
AN11
GPIO
FP18
AN10
GPIO
FP17
AN9
GPIO
FP16
AN8
GPIO
Description
Analog-to-digital converter input channel 7
Keyboard wake-up interrupt 7
General-purpose I/O
Analog-to-digital converter input channel 6
Keyboard wake-up interrupt 6
General-purpose I/O
Analog-to-digital converter input channel 5
Keyboard wake-up interrupt 5
General-purpose I/O
Analog-to-digital converter input channel 4
Keyboard wake-up interrupt 4
General-purpose I/O
Analog-to-digital converter input channel 3
Keyboard wake-up interrupt 3
General-purpose I/O
Analog-to-digital converter input channel 2
Keyboard wake-up interrupt 2
General-purpose I/O
Analog-to-digital converter input channel 1
Keyboard wake-up interrupt 1
General-purpose I/O
Analog-to-digital converter input channel 0
Keyboard wake-up interrupt 0
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 15
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 14
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 13
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 12
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 11
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 10
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 9
General-purpose I/O
LCD driver interface
Analog-to-digital converter input channel 8
General-purpose I/O
Pin Function
after Reset
GPIO
GPIO
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
119
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-1. Detailed Signal Descriptions (Sheet 4 of 6)
Port
Pin
Name
Port M
PM5
PM4
PM3
PM2
Port P
PP5
PP4
PP3
PP2
PP1
PP0
Port S
PS7
PS6
PS5
PS4
PS1
PS0
Pin Function
TXCAN1
GPIO
RXCAN1
GPIO
TXCAN0
GPIO
RXCAN0
GPIO
PWM5
SCL
GPIO
PWM4
SDA
GPIO
PWM3
GPIO
PWM2
RXD1
GPIO
PWM1
GPIO
PWM0
TXD1
GPIO
SS
GPIO
SCK
GPIO
MOSI
GPIO
MISO
GPIO
TXD0
GPIO
RXD0
GPIO
Description
MSCAN1 transmit pin
General-purpose I/O
MSCAN1 receive pin
General-purpose I/O
MSCAN0 transmit pin
General-purpose I/O
MSCAN0 receive pin
General-purpose I/O
Pulse-width modulator channel 5
Inter-integrated circuit serial clock line
General-purpose I/O
Pulse-width modulator channel 4
Inter-integrated circuit serial data line
General-purpose I/O
Pulse-width modulator channel 3
General-purpose I/O
Pulse-width modulator channel 2
Serial communication interface 1 receive pin
General-purpose I/O
Pulse-width modulator channel 1
General-purpose I/O
Pulse-width modulator channel 0
Serial communication interface 1 transmit pin
General-purpose I/O
Serial peripheral interface slave select
input/output in master mode, input in slave mode
General-purpose I/O
Serial peripheral interface serial clock pin
General-purpose I/O
Serial peripheral interface master out/slave in pin
General-purpose I/O
Serial peripheral interface master in/slave out pin
General-purpose I/O
Serial communication interface 0 transmit pin
General-purpose I/O
Serial communication interface 0 receive pin
General-purpose I/O
Pin Function
after Reset
GPIO
GPIO
GPIO
MC9S12HZ256 Data Sheet, Rev. 2.04
120
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-1. Detailed Signal Descriptions (Sheet 5 of 6)
Port
Pin
Name
Port T
PT7
PT6
PT5
PT4
PT3
PT2
PT1
PT0
Port U
PU7
PU6
PU5
PU4
PU3
PU2
PU1
PU0
Pin Function
IOC7
GPIO
IOC6
GPIO
IOC5
GPIO
IOC4
GPIO
FP27
IOC3
GPIO
FP26
IOC2
GPIO
FP25
IOC1
GPIO
FP24
IOC0
GPIO
M1SINP
M1C1P
GPIO
M1SINM
M1C1M
GPIO
M1COSP
M1C0P
GPIO
M1COSM
M1C0M
GPIO
M0SINP
M0C1P
GPIO
M0SINM
M0C1M
GPIO
M0COSP
M0C0P
GPIO
M0COSM
M0C0M
GPIO
Description
Timer channel 7
General-purpose I/O
Timer channel 6
General-purpose I/O
Timer channel 5
General-purpose I/O
Timer channel 4
General-purpose I/O
LCD driver interface
Timer channel 3
General-purpose I/O
LCD driver interface
Timer channel 2
General-purpose I/O
LCD driver interface
Timer channel 1
General-purpose I/O
LCD driver interface
Timer channel 0
General-purpose I/O
SSD1 Sine+ Node
PWM motor controller channel 3
General-purpose I/O
SSD1 Sine- Node
PWM motor controller channel 3
General-purpose I/O
SSD1 Cosine+ Node
PWM motor controller channel 2
General-purpose I/O
SSD1 Cosine- Node
PWM motor controller channel 2
General-purpose I/O
SSD0 Sine+ Node
PWM motor controller channel 1
General-purpose I/O
SSD0 Sine- Node
PWM motor controller channel 1
General-purpose I/O
SSD0 Cosine+ Node
PWM motor controller channel 0
General-purpose I/O
SSD0 Cosine- Node
PWM motor controller channel 0
General-purpose I/O
Pin Function
after Reset
GPIO
GPIO
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
121
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-1. Detailed Signal Descriptions (Sheet 6 of 6)
Port
Pin
Name
Port V
PV7
PV6
PV5
PV4
PV3
PV2
PV1
PV0
Pin Function
M3SINP
M3C1P
GPIO
M3SINM
M3C1M
GPIO
M3COSP
M3C0P
GPIO
M3COSM
M3C0M
GPIO
M2SINP
M2C1P
GPIO
M2SINM
M2C1M
GPIO
M2COSP
M2C0P
GPIO
M2COSM
M2C0M
GPIO
Description
SSD3 sine+ node
PWM motor controller channel 7
General-purpose I/O
SSD3 sine- node
PWM motor controller channel 7
General-purpose I/O
SSD3 cosine+ node
PWM motor controller channel 6
General-purpose I/O
SSD3 cosine- node
PWM motor controller channel 6
General-purpose I/O
SSD2 sine+ node
PWM motor controller channel 5
General-purpose I/O
SSD2 sine- node
PWM motor controller channel 5
General-purpose I/O
SSD2 cosine+ node
PWM motor controller channel 4
General-purpose I/O
SSD2 cosine- node
PWM motor controller channel 4
General-purpose I/O
Pin Function
after Reset
GPIO
MC9S12HZ256 Data Sheet, Rev. 2.04
122
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3
Memory Map and Register Definition
This section provides a detailed description of all registers. Table 4-2 is a standard memory map of port
integration module.
Table 4-2. PIM9HZ256 Memory Map
Address Offset
Use
Access
0x0000
Port T I/O Register (PTT)
0x0001
Port T Input Register (PTIT)
0x0002
Port T Data Direction Register (DDRT)
R/W
0x0003
Port T Reduced Drive Register (RDRT)
R/W
0x0004
Port T Pull Device Enable Register (PERT)
R/W
Port T Polarity Select Register (PPST)
R/W
0x0005
0x0006 - 0x0007
Reserved
R/W
R
—
0x0008
Port S I/O Register (PTS)
0x0009
Port S Input Register (PTIS)
0x000A
Port S Data Direction Register (DDRS)
R/W
0x000B
Port S Reduced Drive Register (RDRS)
R/W
0x000C
Port S Pull Device Enable Register (PERS)
R/W
0x000D
Port S Polarity Select Register (PPSS)
R/W
0x000E
Port S Wired-OR Mode Register (WOMS)
R/W
0x000F
Reserved
0x0010
Port M I/O Register (PTM)
0x0011
Port M Input Register (PTIM)
0x0012
Port M Data Direction Register (DDRM)
R/W
0x0013
Port M Reduced Drive Register (RDRM)
R/W
0x0014
Port M Pull Device Enable Register (PERM)
R/W
0x0015
Port M Polarity Select Register (PPSM)
R/W
0x0016
Port M Wired-OR Mode Register (WOMM)
R/W
0x0017
Reserved
0x0018
Port P I/O Register (PTP)
0x0019
Port P Input Register (PTIP)
0x001A
Port P Data Direction Register (DDRP)
R/W
0x001B
Port P Reduced Drive Register (RDRP)
R/W
0x001C
Port P Pull Device Enable Register (PERP)
R/W
0x001D
Port P Polarity Select Register (PPSP)
R/W
Port P Wired-OR Mode Register (WOMP)
R/W
0x001E
0x001F - 0x002F
R/W
R
—
R/W
R
—
Reserved
R/W
R
—
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
123
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-2. PIM9HZ256 Memory Map (continued)
Address Offset
Use
Access
0x0030
Port L I/O Register (PTL)
0x0031
Port L Input Register (PTIL)
0x0032
Port L Data Direction Register (DDRL)
R/W
0x0033
Port L Reduced Drive Register (RDRL)
R/W
0x0034
Port L Pull Device Enable Register (PERL)
R/W
0x0035
Port L Polarity Select Register (PPSL)
R/W
0x0036 - 0x0037
Reserved
R/W
R
—
0x0038
Port U I/O Register (PTU)
0x0039
Port U Input Register (PTIU)
0x003A
Port U Data Direction Register (DDRU)
R/W
0x003B
Port U Slew Rate Register (SRRU)
R/W
0x003C
Port U Pull Device Enable Register (PERU)
R/W
0x003D
Port U Polarity Select Register (PPSU)
R/W
0x003E - 0x003F
Reserved
R/W
R
—
0x0040
Port V I/O Register (PTV)
0x0041
Port V Input Register (PTIV)
0x0042
Port V Data Direction Register (DDRV)
R/W
0x0043
Port V Slew Rate Register (SRRV)
R/W
0x0044
Port V Pull Device Enable Register (PERV)
R/W
Port V Polarity Select Register (PPSV)
R/W
0x0045
0x0046 - 0x0050
Reserved
R/W
R
—
0x0051
Port AD I/O Register (PTAD)
0x0052
Reserved
R/W
—
0x0053
Port AD Input Register (PTIAD)
R
0x0054
Reserved
—
0x0055
Port AD Data Direction Register (DDRAD)
0x0056
Reserved
—
0x0057
Port AD Reduced Drive Register (RDRAD)
0x0058
Reserved
0x0059
Port AD Pull Device Enable Register (PERAD)
0x005A
Reserved
R/W
—
0x005B
Port AD Polarity Select Register (PPSAD)
Reserved
0x005D
Port AD Interrupt Enable Register (PIEAD)
0x005E
Reserved
0x005F
R/W
—
0x005C
0x0060 - 0x007F
R/W
R/W
—
R/W
—
Port AD Interrupt Flag Register (PIFAD)
Reserved
R/W
—
MC9S12HZ256 Data Sheet, Rev. 2.04
124
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.1
Port AD
Port AD is associated with the analog-to-digital converter (ATD) and keyboard wake-up (KWU)
interrupts. Each pin is assigned to these modules according to the following priority: ATD > KWU >
general-purpose I/O.
For the pins of port AD to be used as inputs, the corresponding bits of the ATDDIEN1 register in the ATD
module must be set to 1 (digital input buffer is enabled). The ATDDIEN1 register does not affect the port
AD pins when they are configured as outputs.
Refer to the ATD block description chapter for information on the ATDDIEN1 register.
During reset, port AD pins are configured as high-impedance analog inputs (digital input buffer is
disabled).
4.3.1.1
Port AD I/O Register (PTAD)
7
6
5
4
3
2
1
0
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
KWU:
KWAD7
KWAD6
KWAD5
KWAD4
KWAD3
KWAD2
KWAD1
KWAD0
ATD:
AN7
AN6
AN55
AN4
AN3
AN2
AN1
AN0
Reset
0
0
0
0
0
0
0
0
R
W
Figure 4-2. Port AD I/O Register (PTAD)
Read: Anytime. Write: Anytime.
If the data direction bit of the associated I/O pin (DDRADx) is set to 1 (output), a write to the
corresponding I/O Register bit sets the value to be driven to the Port AD pin. If the data direction bit of the
associated I/O pin (DDRADx) is set to 0 (input), a write to the corresponding I/O Register bit takes place
but has no effect on the Port AD pin.
If the associated data direction bit (DDRADx) is set to 1 (output), a read returns the value of the I/O register
bit.
If the associated data direction bit (DDRADx) is set to 0 (input) and the associated ATDDIEN1 bits is set
to 0 (digital input buffer is disabled), the associated I/O register bit (PTADx) reads “1”.
If the associated data direction bit (DDRADx) is set to 0 (input) and the associated ATDDIEN1 bits is set
to 1 (digital input buffer is enabled), a read returns the value of the pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
125
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.1.2
R
Port AD Input Register (PTIAD)
7
6
5
4
3
2
1
0
PTIAD7
PTIAD6
PTIAD5
PTIAD4
PTIAD3
PTIAD2
PTIAD1
PTIAD0
1
1
1
1
1
1
1
1
W
Reset
= Reserved or Unimplemented
Figure 4-3. Port AD Input Register (PTIAD)
Read: Anytime. Write: Never; writes to these registers have no effect.
If the ATDDIEN1 bit of the associated I/O pin is set to 0 (digital input buffer is disabled), a read returns a
1. If the ATDDIEN1 bit of the associated I/O pin is set to 1 (digital input buffer is enabled), a read returns
the status of the associated pin.
4.3.1.3
Port AD Data Direction Register (DDRAD)
7
6
5
4
3
2
1
0
DDRAD7
DDRAD6
DDRAD5
DDRAD4
DDRAD3
DDRAD2
DDRAD1
DDRAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-4. Port AD Data Direction Register (DDRAD)
Read: Anytime. Write: Anytime.
This register configures port pins PAD[7:0] as either input or output.
If a data direction bit is 0 (pin configured as input), then a read value on PTADx depends on the associated
ATDDIEN1 bit. If the associated ATDDIEN1 bit is set to 1 (digital input buffer is enabled), a read on
PTADx returns the value on port AD pin. If the associated ATDDIEN1 bit is set to 0 (digital input buffer
is disabled), a read on PTADx returns a 1.
Table 4-3. DDRAD Field Descriptions
Field
Description
7:0
Data Direction Port AD
DDRAD[7:0] 0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
126
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.1.4
Port AD Reduced Drive Register (RDRAD)
7
6
5
4
3
2
1
0
RDRAD7
RDRAD6
RDRAD5
RDRAD4
RDRAD3
RDRAD2
RDRAD1
RDRAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-5. Port AD Reduced Drive Register (RDRAD)
Read: Anytime. Write: Anytime.
This register configures the drive strength of configured output pins as either full or reduced. If a pin is
configured as input, the corresponding Reduced Drive Register bit has no effect.
Table 4-4. RDRAD Field Descriptions
Field
Description
7:0
Reduced Drive Port AD
RDRAD[7:0] 0 Full drive strength at output.
1 Associated pin drives at about 1/3 of the full drive strength.
4.3.1.5
Port AD Pull Device Enable Register (PERAD)
7
6
5
4
3
2
1
0
PERAD7
PERAD6
PERAD5
PERAD4
PERAD3
PERAD2
PERAD1
PERAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-6. Port AD Pull Device Enable Register (PERAD)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input pins. If
a pin is configured as output, the corresponding Pull Device Enable Register bit has no effect.
Table 4-5. PERAD Field Descriptions
Field
Description
7:0
Pull Device Enable Port AD
PERAD[7:0] 0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
127
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.1.6
Port AD Polarity Select Register (PPSAD)
7
6
5
4
3
2
1
0
PPSAD7
PPSAD6
PPSAD5
PPSAD4
PPSAD3
PPSAD2
PPSAD1
PPSAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-7. Port AD Polarity Select Register (PPSAD)
Read: Anytime. Write: Anytime.
The Port AD Polarity Select Register serves a dual purpose by selecting the polarity of the active interrupt
edge as well as selecting a pull-up or pull-down device if enabled (PERADx = 1). The Port AD Polarity
Select Register is effective only when the corresponding Data Direction Register bit is set to 0 (input).
In pull-down mode (PPSADx = 1), a rising edge on a port AD pin sets the corresponding PIFADx bit. In
pull-up mode (PPSADx = 0), a falling edge on a port AD pin sets the corresponding PIFADx bit.
Table 4-6. PPSAD Field Descriptions
Field
Description
7:0
Polarity Select Port AD
PPSAD[7:0] 0 A pull-up device is connected to the associated port AD pin, and detects falling edge for interrupt generation.
1 A pull-down device is connected to the associated port AD pin, and detects rising edge for interrupt
generation.
4.3.1.7
Port AD Interrupt Enable Register (PIEAD)
7
6
5
4
3
2
1
0
PIEAD7
PIEAD6
PIEAD5
PIEAD4
PIEAD3
PIEAD2
PIEAD1
PIEAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-8. Port AD Interrupt Enable Register (PIEAD)
Read: Anytime. Write: Anytime.
This register disables or enables on a per pin basis the edge sensitive external interrupt associated with
port AD.
Table 4-7. PIEAD Field Descriptions
Field
7:0
PIEAD[7:0]
Description
Interrupt Enable Port AD
0 Interrupt is disabled (interrupt flag masked).
1 Interrupt is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
128
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.1.8
Port AD Interrupt Flag Register (PIFAD)
7
6
5
4
3
2
1
0
PIFAD7
PIFAD6
PIFAD5
PIFAD4
PIFAD3
PIFAD2
PIFAD1
PIFAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-9. Port AD Interrupt Flag Register (PIFAD)
Read: Anytime. Write: Anytime.
Each flag is set by an active edge on the associated input pin. The active edge could be rising or falling
based on the state of the corresponding PPSADx bit. To clear each flag, write “1” to the corresponding
PIFADx bit. Writing a “0” has no effect.
NOTE
If the ATDDIEN1 bit of the associated pin is set to 0 (digital input buffer is
disabled), active edges can not be detected.
Table 4-8. PIFAD Field Descriptions
Field
7:0
PIFAD[7:0]
Description
Interrupt Flags Port AD
0 No active edge pending. Writing a “0” has no effect.
1 Active edge on the associated bit has occurred (an interrupt will occur if the associated enable bit is set).
Writing a “1” clears the associated flag.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
129
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.2
Port L
Port L is associated with the analog-to-digital converter (ATD) and the liquid crystal display (LCD) driver.
If the ATD module is enabled, the AN[15:8] inputs of ATD module are available on port L pins PL[7:0].
If the corresponding LCD frontplane drivers are enabled, the FP[31:29] and FP[19:16] outputs of LCD
module are available on port L pins PL[7:0] and the general purpose I/Os are disabled.
For the pins of port L to be used as inputs, the corresponding LCD frontplane drivers must be disabled and
the associated ATDDIEN0 register in the ATD module must be set to 1 (digital input buffer is enabled).
The ATDDIEN0 register does not affect the port L pins when they are configured as outputs.
Refer to the LCD block description chapter for information on enabling and disabling the LCD and its
frontplane drivers. Refer to the ATD block description chapter for information on the ATDDIEN0 register.
During reset, port L pins are configured as inputs with pull down.
4.3.2.1
Port L I/O Register (PTL)
7
6
5
4
3
2
1
0
PTL7
PTL6
PTL5
PTL4
PTL3
PTL2
PTL1
PTL0
ATD:
AN15
AN14
AN13
AN12
AN11
AN10
AN9
AN8
LCD:
1
1
1
1
1
1
1
1
Reset
0
0
0
0
0
0
0
0
R
W
Figure 4-10. Port L I/O Register (PTL)
Read: Anytime. Write: Anytime.
If the data direction bit of the associated I/O pin (DDRLx) is set to 1 (output), a write to the corresponding
I/O Register bit sets the value to be driven to the Port L pin. If the data direction bit of the associated I/O
pin (DDRLx) is set to 0 (input), a write to the corresponding I/O Register bit takes place but has no effect
on the Port L pin.
If the associated data direction bit (DDRLx) is set to 1 (output), a read returns the value of the I/O register
bit.
If the associated data direction bit (DDRLx) is set to 0 (input) and the associated ATDDIEN0 bits is set to
0 (digital input buffer is disabled), the associated I/O register bit (PTLx) reads “1”.
If the associated data direction bit (DDRLx) is set to 0 (input), the associated ATDDIEN0 bit is set to 1
(digital input buffer is enabled), and the LCD frontplane driver is enabled (and LCD module is enabled),
the associated I/O register bit (PTLx) reads “1”.
If the associated data direction bit (DDRLx) is set to 0 (input), the associated ATDDIEN0 bit is set to 1
(digital input buffer is enabled), and the LCD frontplane driver is disabled (or LCD module is disabled),
a read returns the value of the pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
130
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.2.2
R
Port L Input Register (PTIL)
7
6
5
4
3
2
1
0
PTIL7
PTIL6
PTIL5
PTIL4
PTIL3
PTIL2
PTIL1
PTIL0
1
1
1
1
1
1
1
1
W
Reset
= Reserved or Unimplemented
Figure 4-11. Port L Input Register (PTIL)
Read: Anytime. Write: Never, writes to this register have no effect.
If the LCD frontplane driver of an associated I/O pin is enabled (and LCD module is enabled) or the
associated ATDDIEN0 bit is set to 0 (digital input buffer is disabled), a read returns a 1.
If the LCD frontplane driver of an associated I/O pin is disabled (or LCD module is disabled) and the
associated ATDDIEN0 bit is set to 1 (digital input buffer is enabled), a read returns the status of the
associated pin.
4.3.2.3
Port L Data Direction Register (DDRL)
7
6
5
4
3
2
1
0
DDRL7
DDRL6
DDRL5
DDRL4
DDRL3
DDRL2
DDRL1
DDRL0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-12. Port L Data Direction Register (DDRL)
Read: Anytime. Write: Anytime.
This register configures port pins PL[7:0] as either input or output.
If a LCD frontplane driver is enabled (and LCD module is enabled), it outputs an analog signal to the
corresponding pin and the associated Data Direction Register bit has no effect. If a LCD frontplane driver
is disabled (or LCD module is disabled), the corresponding Data Direction Register bit reverts to control
the I/O direction of the associated pin.
Table 4-9. DDRL Field Descriptions
Field
7:0
DDRL[7:0]
Description
Data Direction Port L
0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
131
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.2.4
Port L Reduced Drive Register (RDRL)
7
6
5
4
3
2
1
0
RDRL7
RDRL6
RDRL5
RDRL4
RDRL3
RDRL2
RDRL1
RDRL0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-13. Port L Reduced Drive Register (RDRL)
Read: Anytime. Write: Anytime.
This register configures the drive strength of configured output pins as either full or reduced. If a pin is
configured as input, the corresponding Reduced Drive Register bit has no effect.
Table 4-10. RDRL Field Descriptions
Field
7:0
RDRL[7:0]
4.3.2.5
Description
Reduced Drive Port L
0 Full drive strength at output.
1 Associated pin drives at about 1/3 of the full drive strength.
Port L Pull Device Enable Register (PERL)
7
6
5
4
3
2
1
0
PERL7
PERL6
PERL5
PERL4
PERL3
PERL2
PERL1
PERL0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 4-14. Port L Pull Device Enable Register (PERL)
Read:Anytime. Write:Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input pins. If
a pin is configured as output, the corresponding Pull Device Enable Register bit has no effect.
Table 4-11. PERL Field Descriptions
Field
7:0
PERL[7:0]
Description
Pull Device Enable Port L
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
132
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.2.6
Port L Polarity Select Register (PPSL)
7
6
5
4
3
2
1
0
PPSL7
PPSL6
PPSL5
PPSL4
PPSL3
PPSL2
PPSL1
PPSL0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 4-15. Port L Polarity Select Register (PPSL)
Read: Anytime. Write: Anytime.
The Port L Polarity Select Register selects whether a pull-down or a pull-up device is connected to the pin.
The Port L Polarity Select Register is effective only when the corresponding Data Direction Register bit
is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
Table 4-12. PPSL Field Descriptions
Field
7:0
PPSL[7:0]
Description
Pull Select Port L
0 A pull-up device is connected to the associated port L pin.
1 A pull-down device is connected to the associated port L pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
133
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.3
Port M
Port M is associated with Freescale’s scalable controller area network (CAN1 and CAN0) modules. Each
pin is assigned to these modules according to the following priority: CAN1/CAN0 > general-purpose I/O.
When the CAN1 module is enabled, PM[5:4] pins become TXCAN1 (transmitter) and RXCAN1
(receiver) pins for the CAN1 module. When the CAN0 module is enabled, PM[3:2] pins become TXCAN0
(transmitter) and RXCAN0 (receiver) pins for the CAN0 module. Refer to the MSCAN block description
chapter for information on enabling and disabling the CAN module.
During reset, port M pins are configured as high-impedance inputs.
4.3.3.1
Port M I/O Register (PTM)
R
7
6
0
0
5
4
3
2
PTM5
PTM4
PTM3
PTM2
TXCAN1
RXCAN1
TXCAN0
RXCAN0
0
0
0
0
1
0
0
0
0
0
W
CAN0/CAN1:
Reset
0
0
= Reserved or Unimplemented
Figure 4-16. Port M I/O Register (PTM)
Read: Anytime. Write: Anytime.
If the associated data direction bit (DDRMx) is set to 1 (output), a read returns the value of the I/O register
bit. If the associated data direction bit (DDRMx) is set to 0 (input), a read returns the value of the pin.
4.3.3.2
R
Port M Input Register (PTIM)
7
6
5
4
3
2
1
0
0
0
PTIM5
PTIM4
PTIM3
PTIM2
0
0
0
0
u
u
u
u
0
0
W
Reset
= Reserved or Unimplemented
u = Unaffected by reset
Figure 4-17. Port M Input Register (PTIM)
Read: Anytime. Write: Never, writes to this register have no effect.
This register always reads back the status of the associated pins.
MC9S12HZ256 Data Sheet, Rev. 2.04
134
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.3.3
R
Port M Data Direction Register (DDRM)
7
6
0
0
5
4
3
2
DDRM5
DDRM4
DDRM3
DDRM2
0
0
0
0
1
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-18. Port M Data Direction Register (DDRM)
Read: Anytime. Write: Anytime.
This register configures port pins PM[5:2] as either input or output.
When a CAN module is enabled, the corresponding transmitter (TXCANx) pin becomes an output, the
corresponding receiver (RXCANx) pin becomes an input, and the associated Data Direction Register bits
have no effect. If a CAN module is disabled, the corresponding Data Direction Register bit reverts to
control the I/O direction of the associated pin.
Table 4-13. DDRM Field Descriptions
Field
5:2
DDRM[5:2]
4.3.3.4
R
Description
Data Direction Port M
0 Associated pin is configured as input.
1 Associated pin is configured as output.
Port M Reduced Drive Register (RDRM)
7
6
0
0
5
4
3
2
RDRM5
RDRM4
RDRM3
RDRM2
0
0
0
0
1
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-19. Port M Reduced Drive Register (RDRM)
Read: Anytime. Write: Anytime.
This register configures the drive strength of configured output pins as either full or reduced. If a pin is
configured as input, the corresponding Reduced Drive Register bit has no effect.
Table 4-14. RDRM Field Descriptions
Field
5:2
RDRM[5:2]
Description
Reduced Drive Port M
0 Full drive strength at output
1 Associated pin drives at about 1/3 of the full drive strength.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
135
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.3.5
R
Port M Pull Device Enable Register (PERM)
7
6
0
0
5
4
3
2
PERM5
PERM4
PERM3
PERM2
0
0
0
0
1
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-20. Port M Pull Device Enable Register (PERM)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input or
wired-or output pins. If a pin is configured as push-pull output, the corresponding Pull Device Enable
Register bit has no effect.
Table 4-15. PERM Field Descriptions
Field
5:2
PERM[5:2]
4.3.3.6
R
Description
Pull Device Enable Port M
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
Port M Polarity Select Register (PPSM)
7
6
0
0
5
4
3
2
PPSM5
PPSM4
PPSM3
PPSM2
0
0
0
0
1
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-21. Port M Polarity Select Register (PPSM)
Read: Anytime. Write: Anytime.
The Port M Polarity Select Register selects whether a pull-down or a pull-up device is connected to the
pin. The Port M Polarity Select Register is effective only when the corresponding Data Direction Register
bit is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
If a CAN module is enabled, a pull-up device can be activated on the receiver pin, and on the transmitter
pin if the corresponding wired-OR mode bit is set. Pull-down devices can not be activated on CAN pins.
MC9S12HZ256 Data Sheet, Rev. 2.04
136
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-16. PPSM Field Descriptions
Field
5:2
PPSM[5:2]
4.3.3.7
R
Description
Pull Select Port M
0 A pull-up device is connected to the associated port M pin.
1 A pull-down device is connected to the associated port M pin.
Port M Wired-OR Mode Register (WOMM)
7
6
0
0
5
4
3
2
WOMM5
WOMM4
WOMM3
WOMM2
0
0
0
0
1
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-22. Port M Wired-OR Mode Register (WOMM)
Read: Anytime. Write: Anytime.
This register selects whether a port M output is configured as push-pull or wired-or. When a Wired-OR
Mode Register bit is set to 1, the corresponding output pin is driven active low only (open drain) and a
high level is not driven. A Wired-OR Mode Register bit has no effect if the corresponding pin is configured
as an input.
These bits apply also to the CAN transmitter and allow a multipoint connection of several serial modules.
Table 4-17. WOMM Field Descriptions
Field
Description
5:2
Wired-OR Mode Port M
WOMM[5:2] 0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
137
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.4
Port P
Port P is associated with the Pulse Width Modulator (PWM), serial communication interface (SCI1) and
Inter-IC bus (IIC) modules. Each pin is assigned to these modules according to the following priority:
PWM > SCI1/IIC > general-purpose I/O.
When a PWM channel is enabled, the corresponding pin becomes a PWM output with the exception of
PP[5] which can be PWM input or output. Refer to the PWM block description chapter for information on
enabling and disabling the PWM channels.
When the IIC bus is enabled, the PP[5:4] pins become SCL and SDA respectively as long as the
corresponding PWM channels are disabled. Refer to the IIC block description chapter for information on
enabling and disabling the IIC bus.
When the SCI1 receiver and transmitter are enabled, the PP[2] and PP[0] pins become RXD1 and TXD1
respectively as long as the corresponding PWM channels are disabled. Refer to the SCI block description
chapter for information on enabling and disabling the SCI receiver and transmitter.
During reset, port P pins are configured as high-impedance inputs.
4.3.4.1
R
Port P I/O Register (PTP)
7
6
0
0
5
4
3
2
1
0
PTP5
PTP4
PTP3
PTP2
PTP1
PTP0
SCL
SDA
PWM5
PWM4
PWM3
PWM2
PWM1
PWM0
0
0
0
0
0
0
W
SCI1/IIC:
PWM:
Reset
0
0
RXD1
TXD1
= Reserved or Unimplemented
Figure 4-23. Port P I/O Register (PTP)
Read: Anytime. Write: Anytime.
If the associated data direction bit (DDRPx) is set to 1 (output), a read returns the value of the I/O register
bit. If the associated data direction bit (DDRPx) is set to 0 (input), a read returns the value of the pin.
The PWM function takes precedence over the general-purpose I/O function if the associated PWM
channel is enabled. The PWM channels 4-0 are outputs if the respective channels are enabled. PWM
channel 5 can be an output, or an input if the shutdown feature is enabled.
The IIC function takes precedence over the general-purpose I/O function if the IIC bus is enabled and the
corresponding PWM channels remain disabled. The SDA and SCL pins are bidirectional with outputs
configured as open-drain.
If enabled, the SCI1 transmitter takes precedence over the general-purpose I/O function, and the
corresponding TXD1 pin is configured as an output. If enabled, the SCI1 receiver takes precedence over
the general-purpose I/O function, and the corresponding RXD1 pin is configured as an input.
MC9S12HZ256 Data Sheet, Rev. 2.04
138
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.4.2
R
Port P Input Register (PTIP)
7
6
5
4
3
2
1
0
0
0
PTIP5
PTIP4
PTIP3
PTIP2
PTIP1
PTIP0
0
0
u
u
u
u
u
u
W
Reset
= Reserved or Unimplemented
u = Unaffected by reset
Figure 4-24. Port P I/O Register (PTP)
Read: Anytime. Write: Never, writes to this register have no effect.
This register always reads back the status of the associated pins.
4.3.4.3
R
Port P Data Direction Register (DDRP)
7
6
0
0
5
4
3
2
1
0
DDRP5
DDRP4
DDRP3
DDRP2
DDRP1
DDRP0
0
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-25. Port P Data Direction Register (DDRP)
Read: Anytime. Write: Anytime.
This register configures port pins PP[5:0] as either input or output.
If a PWM channel is enabled, the corresponding pin is forced to be an output and the associated Data
Direction Register bit has no effect. Channel 5 can also force the corresponding pin to be an input if the
shutdown feature is enabled.
When the IIC bus is enabled, the PP[5:4] pins become the SCL and SDA bidirectional pins respectively
as long as the corresponding PWM channels are disabled. The associated Data Direction Register bits have
no effect.
When the SCI1 transmitter is enabled, the PP[0] pin becomes the TXD1 output pin and the associated Data
Direction Register bit has no effect. When the SCI1 receiver is enabled, the PP[2] pin becomes the RXD1
input pin and the associated Data Direction Register bit has no effect.
If the PWM, IIC and SCI1 functions are disabled, the corresponding Data Direction Register bit reverts to
control the I/O direction of the associated pin.
Table 4-18. DDRP Field Descriptions
Field
5:0
DDRP[5:0]
Description
Data Direction Port P
0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
139
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.4.4
R
Port P Reduced Drive Register (RDRP)
7
6
0
0
5
4
3
2
1
0
RDRP5
RDRP4
RDRP3
RDRP2
RDRP1
RDRP0
0
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-26. Port P Reduced Drive Register (RDRP)
Read:Anytime. Write:Anytime.
This register configures the drive strength of configured output pins as either full or reduced. If a pin is
configured as input, the corresponding Reduced Drive Register bit has no effect.
Table 4-19. RDRP Field Descriptions
Field
5:0
RDRP[5:0]
Description
Reduced Drive Port P
0 Full drive strength at output.
1 Associated pin drives at about 1/3 of the full drive strength.
MC9S12HZ256 Data Sheet, Rev. 2.04
140
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.4.5
R
Port P Pull Device Enable Register (PERP)
7
6
0
0
5
4
3
2
1
0
PERP5
PERP4
PERP3
PERP2
PERP1
PERP0
0
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-27. Port P Pull Device Enable Register (PERP)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input pins. If
a pin is configured as output, the corresponding Pull Device Enable Register bit has no effect.
Table 4-20. PERP Field Descriptions
Field
5:0
PERP[5:0]
4.3.4.6
R
Description
Pull Device Enable Port P
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
Port P Polarity Select Register (PPSP)
7
6
0
0
5
4
3
2
1
0
PPSP5
PPSP4
PPSP3
PPSP2
PPSP1
PPSP0
0
0
0
0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-28. Port P Polarity Select Register (PPSP)
Read: Anytime. Write: Anytime.
The Port P Polarity Select Register selects whether a pull-down or a pull-up device is connected to the pin.
The Port P Polarity Select Register is effective only when the corresponding Data Direction Register bit
is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
Table 4-21. PPSP Field Descriptions
Field
5:0
PPSP[5:0]
Description
Polarity Select Port P
0 A pull-up device is connected to the associated port P pin.
1 A pull-down device is connected to the associated port P pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
141
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.4.7
R
Port P Wired-OR Mode Register (WOMP)
7
6
0
0
5
4
3
WOMP5
WOMP4
0
0
2
0
1
0
0
WOMP2
WOMPO
W
Reset
0
0
0
0
0
0
= Reserved or Unimplemented
Figure 4-29. Port P Wired-OR Mode Register (WOMP)
Read: Anytime. Write: Anytime.
This register selects whether a port P output is configured as push-pull or wired-or. When a Wired-OR
Mode Register bit is set to 1, the corresponding output pin is driven active low only (open drain) and a
high level is not driven. A Wired-OR Mode Register bit has no effect if the corresponding pin is configured
as an input.
If the IIC is enabled and the corresponding PWM channels are disabled, the PP[5:4] pins are configured
as wired-or and the corresponding Wired-OR Mode Register bits have no effect.
Table 4-22. WOMP Field Descriptions
Field
Description
5:4
Wired-OR Mode Port P
WOMP[5:4] 0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.
2
WOMP2
Wired-OR Mode Port P
0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.
0
WOMP0
Wired-OR Mode Port P
0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.
MC9S12HZ256 Data Sheet, Rev. 2.04
142
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.5
Port S
Port S is associated with the serial peripheral interface (SPI) and serial communication interface (SCI0).
Each pin is assigned to these modules according to the following priority: SPI/SCI0 > general-purpose I/O.
When the SPI is enabled, the PS[7:4] pins become SS, SCK, MOSI, and MISO respectively. Refer to the
SPI block description chapter for information on enabling and disabling the SPI.
When the SCI0 receiver and transmitter are enabled, the PS[1:0] pins become TXD0 and RXD0
respectively. Refer to the SCI block description chapter for information on enabling and disabling the SCI
receiver and transmitter.
During reset, port S pins are configured as high-impedance inputs.
4.3.5.1
Port S I/O Register (PTS)
7
6
5
4
1
0
PTS7
PTS6
PTS5
PTS4
PTS1
PTS0
SS
SCK
MOSI
MISO
TXD0
RXD0
0
0
0
0
0
0
R
3
2
0
0
W
SPI/SCI:
Reset
0
0
= Reserved or Unimplemented
Figure 4-30. Port S I/O Register (PTS)
Read: Anytime. Write: Anytime.
If the associated data direction bit (DDRSx) is set to 1 (output), a read returns the value of the I/O register
bit. If the associated data direction bit (DDRSx) is set to 0 (input), a read returns the value of the pin.
The SPI function takes precedence over the general-purpose I/O function if the SPI is enabled.
If enabled, the SCI0 transmitter takes precedence over the general-purpose I/O function, and the
corresponding TXD0 pin is configured as an output. If enabled, the SCI0 receiver takes precedence over
the general-purpose I/O function, and the corresponding RXD0 pin is configured as an input.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
143
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.5.2
R
Port S Input Register (PTIS)
7
6
5
4
3
2
1
0
PTIS7
PTIS6
PTIS5
PTIS4
0
0
PTIS1
PTIS0
u
u
u
u
0
0
u
u
1
0
DDRS1
DDRS0
0
0
W
Reset
= Reserved or Unimplemented
u = Unaffected by reset
Figure 4-31. Port S Input Register (PTIS)
Read: Anytime. Write: Never, writes to this register have no effect.
This register always reads back the status of the associated pins.
4.3.5.3
Port S Data Direction Register (DDRS)
7
6
5
4
DDRS7
DDRS6
DDRS5
DDRS4
0
0
0
0
R
3
2
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-32. Port S Data Direction Register (DDRS)
Read: Anytime. Write: Anytime.
This register configures port pins PS[7:4] and PS[2:0] as either input or output.
When the SPI is enabled, the PS[7:4] pins become the SPI bidirectional pins. The associated Data
Direction Register bits have no effect.
When the SCI0 transmitter is enabled, the PS[1] pin becomes the TXD0 output pin and the associated Data
Direction Register bit has no effect. When the SCI0 receiver is enabled, the PS[0] pin becomes the RXD0
input pin and the associated Data Direction Register bit has no effect.
If the SPI and SCI0 functions are disabled, the corresponding Data Direction Register bit reverts to control
the I/O direction of the associated pin.
Table 4-23. DDRS Field Descriptions
Field
Description
7:4
DDRS[7:4]
Data Direction Port S
0 Associated pin is configured as input.
1 Associated pin is configured as output.
1:0
DDRS[1:0]
Data Direction Port S
0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
144
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.5.4
Port S Reduced Drive Register (RDRS)
7
6
5
4
RDRS7
RDRS6
RDRS5
RDRS4
0
0
0
0
R
3
2
0
0
1
0
RDRS1
RDRS0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-33. Port S Reduced Drive Register (RDRS)
Read: Anytime. Write: Anytime.
This register configures the drive strength of configured output pins as either full or reduced. If a pin is
configured as input, the corresponding Reduced Drive Register bit has no effect.
Table 4-24. RDRS Field Descriptions
Field
Description
7:4
RDRS[7:4]
Reduced Drive Port S
0 Full drive strength at output.
1 Associated pin drives at about 1/3 of the full drive strength.
1:0
RDRS[1:0]
Reduced Drive Port S
0 Full drive strength at output.
1 Associated pin drives at about 1/3 of the full drive strength.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
145
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.5.5
Port S Pull Device Enable Register (PERS)
7
6
5
4
PERS7
PERS6
PERS5
PERS4
0
0
0
0
R
3
2
0
0
1
0
PERS1
PERS0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-34. Port S Pull Device Enable Register (PERS)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input or
wired-or (open drain) output pins. If a pin is configured as push-pull output, the corresponding Pull Device
Enable Register bit has no effect.
Table 4-25. PERS Field Descriptions
Field
Description
7:4
PERS[7:4]
Pull Device Enable Port S
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
1:0
PERS[1:0]
Pull Device Enable Port S
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
4.3.5.6
Port S Polarity Select Register (PPSS)
7
6
5
4
PPSS7
PPSS6
PPSS5
PPSS4
0
0
0
0
R
3
2
0
0
1
0
PPSS1
PPSS0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-35. Port S Polarity Select Register (PPSS)
Read: Anytime. Write: Anytime.
The Port S Polarity Select Register selects whether a pull-down or a pull-up device is connected to the pin.
The Port S Polarity Select Register is effective only when the corresponding Data Direction Register bit
is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
MC9S12HZ256 Data Sheet, Rev. 2.04
146
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
Table 4-26. PPSS Field Descriptions
Field
Description
7:4
PPSS[7:4]
Pull Select Port S
0 A pull-up device is connected to the associated port S pin.
1 A pull-down device is connected to the associated port S pin.
1:0
PPSS[1:0]
Pull Select Port S
0 A pull-up device is connected to the associated port S pin.
1 A pull-down device is connected to the associated port S pin.
4.3.5.7
Port S Wired-OR Mode Register (WOMS)
7
6
5
4
WOMS7
WOMS6
WOMS5
WOMS4
0
0
0
0
R
3
2
0
0
1
0
WOMS1
WOMS0
0
0
W
Reset
0
0
= Reserved or Unimplemented
Figure 4-36. Port S Wired-OR Mode Register (WOMS)
Read: Anytime. Write: Anytime.
This register selects whether a port S output is configured as push-pull or wired-or. When a Wired-OR
Mode Register bit is set to 1, the corresponding output pin is driven active low only (open drain) and a
high level is not driven. A Wired-OR Mode Register bit has no effect if the corresponding pin is configured
as an input.
Table 4-27. WOMS Field Descriptions
Field
Description
7:4
Wired-OR Mode Port S
WOMS[7:4] 0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.
1:0
Wired-OR Mode Port S
WOMS[1:0] 0 Output buffers operate as push-pull outputs.
1 Output buffers operate as open-drain outputs.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
147
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.6
Port T
Port T is associated with the 8-channel timer (TIM) and the liquid crystal display (LCD) driver. Each pin
is assigned to these modules according to the following priority:
LCD Driver > timer > general-purpose I/O.
If the corresponding LCD frontplane drivers are enabled (and LCD module is enabled), the FP[27:24]
outputs of the LCD module are available on port T pins PT[3:0].
If the corresponding LCD frontplane drivers are disabled (or LCD module is disabled) and the timer is
enabled, the timer channels configured for output compare are available on port T pins PT[3:0].
Refer to the LCD block description chapter for information on enabling and disabling the LCD and its
frontplane drivers.Refer to the TIM block description chapter for information on enabling and disabling
the TIM module.
During reset, port T pins are configured as inputs with pull down.
4.3.6.1
Port T I/O Register (PTT)
7
6
5
4
3
2
1
0
PTT7
PTT6
PTT5
PTT4
PTT3
PTT2
PTT1
PTT0
OC7
OC6
OC5
OC4
OC3
OC2
OC1
OC0
1
1
1
1
0
0
0
0
R
W
TIM:
LCD:
Reset
0
0
0
0
Figure 4-37. Port T I/O Register (PTT)
Read: Anytime. Write: Anytime.
If the associated data direction bit (DDRTx) is set to 1 (output), a read returns the value of the I/O register
bit.
If the associated data direction bit (DDRTx) is set to 0 (input) and the LCD frontplane driver is enabled
(and LCD module is enabled), the associated I/O register bit (PTTx) reads “1”.
If the associated data direction bit (DDRTx) is set to 0 (input) and the LCD frontplane driver is disabled
(or LCD module is disabled), a read returns the value of the pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
148
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.6.2
R
Port T Input Register (PTIT)
7
6
5
4
3
2
1
0
PTIT7
PTIT6
PTIT5
PTIT4
PTIT3
PTIT2
PTIT1
PTIT0
u
u
u
u
u
u
u
u
W
Reset
= Reserved or Unimplemented
u = Unaffected by reset
Figure 4-38. Port T Input Register (PTIT)
Read: Anytime. Write: Never, writes to this register have no effect.
If the LCD frontplane driver of an associated I/O pin is enabled (and LCD module is enabled), a read
returns a 1.
If the LCD frontplane driver of the associated I/O pin is disabled (or LCD module is disabled), a read
returns the status of the associated pin.
4.3.6.3
Port T Data Direction Register (DDRT)
7
6
5
4
3
2
1
0
DDRT7
DDRT6
DDRT5
DDRT4
DDRT3
DDRT2
DDRT1
DDRT0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-39. Port T Data Direction Register (DDRT)
Read: Anytime. Write: Anytime.
This register configures port pins PT[7:0] as either input or output.
If a LCD frontplane driver is enabled (and LCD module is enabled), it outputs an analog signal to the
corresponding pin and the associated Data Direction Register bit has no effect. If a LCD frontplane driver
is disabled (or LCD module is disabled), the corresponding Data Direction Register bit reverts to control
the I/O direction of the associated pin.
If the TIM module is enabled, each port pin configured for output compare is forced to be an output and
the associated Data Direction Register bit has no effect. If the associated timer output compare is disabled,
the corresponding Data Direction Register bit reverts to control the I/O direction of the associated pin.
If the TIM module is enabled, each port pin configured as an input capture has the corresponding Data
Direction Register bit controlling the I/O direction of the associated pin.
Table 4-28. DDRT Field Descriptions
Field
7:0
DDRT[7:0]
Description
Data Direction Port T
0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
149
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.6.4
Port T Reduced Drive Register (RDRT)
7
6
5
4
3
2
1
0
RDRT7
RDRT6
RDRT5
RDRT4
RDRT3
RDRT2
RDRT1
RDRT0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-40. Port T Reduced Drive Register (RDRT)
Read: Anytime. Write: Anytime.
This register configures the drive strength of configured output pins as either full or reduced. If a pin is
configured as input, the corresponding Reduced Drive Register bit has no effect.
Table 4-29. RDRT Field Descriptions
Field
7:0
RDRT[7:0]
Description
Reduced Drive Port T
0 Full drive strength at output.
1 Associated pin drives at about 1/3 of the full drive strength.
MC9S12HZ256 Data Sheet, Rev. 2.04
150
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.6.5
Port T Pull Device Enable Register (PERT)
7
6
5
4
3
2
1
0
PERT7
PERT6
PERT5
PERT4
PERT3
PERT2
PERT1
PERT0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 4-41. Port T Pull Device Enable Register (PERT)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input pins. If
a pin is configured as output, the corresponding Pull Device Enable Register bit has no effect.
Table 4-30. PERT Field Descriptions
Field
7:0
PERT[7:0]
4.3.6.6
Description
Pull Device Enable Port T
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
Port T Polarity Select Register (PPST)
7
6
5
4
3
2
1
0
PPST7
PPST6
PPST5
PPST4
PPST3
PPST2
PPST1
PPST0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 4-42. Port T Polarity Select Register (PPST)
Read: Anytime. Write: Anytime.
The Port T Polarity Select Register selects whether a pull-down or a pull-up device is connected to the pin.
The Port T Polarity Select Register is effective only when the corresponding Data Direction Register bit
is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
Table 4-31. PPST Field Descriptions
Field
7:0
PPST[7:0]
Description
Pull Select Port T
0 A pull-up device is connected to the associated port T pin.
1 A pull-down device is connected to the associated port T pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
151
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.7
Port U
Port U is associated with the stepper stall detect (SSD1 and SSD0) and motor controller (MC1 and MC0)
modules. Each pin is assigned to these modules according to the following priority: SSD1/SSD0 >
MC1/MC0 > general-purpose I/O.
If SSD1 module is enabled, the PU[7:4] pins are controlled by the SSD1 module. If SSD1 module is
disabled, the PU[7:4] pins are controlled by the motor control PWM channels 3 and 2 (MC1).
If SSD0 module is enabled, the PU[3:0] pins are controlled by the SSD0 module. If SSD0 module is
disabled, the PU[3:0] pins are controlled by the motor control PWM channels 1 and 0 (MC0).
Refer to the SSD and MC block description chapters for information on enabling and disabling the SSD
module and the motor control PWM channels respectively.
During reset, port U pins are configured as high-impedance inputs.
4.3.7.1
Port U I/O Register (PTU)
7
6
5
4
3
2
1
0
PTU7
PTU6
PTU5
PTU4
PTU3
PTU2
PTU1
PTU0
MC:
M1C1P
M1C1M
M1COP
M1COM
M0C1P
M0C1M
M0C0P
M0C0M
SSD1/
SSD0:
M1SINP
M1SINM
M1COSP
M1COSM
M0SINP
M0SINM
M1COSP
M0COSM
Reset
0
0
0
0
0
0
0
0
R
W
Figure 4-43. Port U I/O Register (PTU)
Read: Anytime. Write: Anytime.
If the associated data direction bit (DDRUx) is set to 1 (output), a read returns the value of the I/O register
bit.
If the associated data direction bit (DDRUx) is set to 0 (input) and the slew rate is enabled, the associated
I/O register bit (PTUx) reads “1”.
If the associated data direction bit (DDRUx) is set to 0 (input) and the slew rate is disabled, a read returns
the value of the pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
152
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.7.2
R
Port U Input Register (PTIU)
7
6
5
4
3
2
1
0
PTIU7
PTIU6
PTIU5
PTIU4
PTIU3
PTIU2
PTIU1
PTIU0
u
u
u
u
u
u
u
u
W
Reset
= Reserved or Unimplemented
u = Unaffected by reset
Figure 4-44. Port U Input Register (PTIU)
Read: Anytime. Write: Never, writes to this register have no effect.
If the associated slew rate control is enabled (digital input buffer is disabled), a read returns a “1”. If the
associated slew rate control is disabled (digital input buffer is enabled), a read returns the status of the
associated pin.
4.3.7.3
Port U Data Direction Register (DDRU)
7
6
5
4
3
2
1
0
DDRU7
DDRU6
DDRU5
DDRU4
DDRU3
DDRU2
DDRU1
DDRU0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-45. Port U Data Direction Register (DDRU)
Read: Anytime. Write: Anytime.
This register configures port pins PU[7:0] as either input or output.
When enabled, the SSD or MC modules force the I/O state to be an output for each associated pin and the
associated Data Direction Register bit has no effect. If the SSD and MC modules are disabled, the
corresponding Data Direction Register bits revert to control the I/O direction of the associated pins.
Table 4-32. DDRU Field Descriptions
Field
7:0
DDRU[7:0]
Description
Data Direction Port U
0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
153
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.7.4
Port U Slew Rate Register (SRRU)
7
6
5
4
3
2
1
0
SRRU7
SRRU6
SRRU5
SRRU4
SRRU3
SRRU2
SRRU1
SRRU0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-46. Port U Slew Rate Register (SRRU)
Read: Anytime. Write: Anytime.
This register enables the slew rate control and disables the digital input buffer for port pins PU[7:0].
Table 4-33. SRRU Field Descriptions
Field
7:0
SRRU[7:0]
4.3.7.5
Description
Slew Rate Port U
0 Disables slew rate control and enables digital input buffer.
1 Enables slew rate control and disables digital input buffer.
Port U Pull Device Enable Register (PERU)
7
6
5
4
3
2
1
0
PERU7
PERU6
PERU5
PERU4
PERU3
PERU2
PERU1
PERU0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-47. Port U Pull Device Enable Register (PERU)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input pins. If
a pin is configured as output, the corresponding Pull Device Enable Register bit has no effect.
Table 4-34. PERU Field Descriptions
Field
7:0
PERU[7:0]
Description
Pull Device Enable Port U
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
154
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.7.6
Port U Polarity Select Register (PPSU)
7
6
5
4
3
2
1
0
PPSU7
PPSU6
PPSU5
PPSU4
PPSU3
PPSU2
PPSU1
PPSU0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-48. Port U Polarity Select Register (PPSU)
Read: Anytime. Write: Anytime.
The Port U Polarity Select Register selects whether a pull-down or a pull-up device is connected to the pin.
The Port U Polarity Select Register is effective only when the corresponding Data Direction Register bit
is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
Table 4-35. PPSU Field Descriptions
Field
7:0
PPSU[7:0]
Description
Pull Select Port U
0 A pull-up device is connected to the associated port U pin.
1 A pull-down device is connected to the associated port U pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
155
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.8
Port V
Port V is associated with the stepper stall detect (SSD3 and SSD2) and motor controller (MC3 and MC2)
modules. Each pin is assigned to these modules according to the following priority: SSD3/SSD2 >
MC3/MC2 > general-purpose I/O.
If SSD3 module is enabled, the PV[7:4] pins are controlled by the SSD3 module. If SSD3 module is
disabled, the PV[7:4] pins are controlled by the motor control PWM channels 7 and 6 (MC3).
If SSD2 module is enabled, the PV[3:0] pins are controlled by the SSD2 module. If SSD2 module is
disabled, the PV[3:0] pins are controlled by the motor control PWM channels 5 and 4 (MC2).
Refer to the SSD and MC block description chapters for information on enabling and disabling the SSD
module and the motor control PWM channels respectively.
During reset, port V pins are configured as high-impedance inputs.
4.3.8.1
Port V I/O Register (PTV)
7
6
5
4
3
2
1
0
PTV7
PTV6
PTV5
PTV4
PTV3
PTV2
PTV1
PTV0
MC:
M3C1P
M3C1M
M3C0P
M3C0M
M2C1P
M2C1M
M2C0P
M2C0M
SSD3/
SSD2
M3SINP
M3SINM
M3COSP
M3COSM
M2SINP
M2SINM
M2COSP
M2COSM
Reset
0
0
0
0
0
0
0
0
R
W
Figure 4-49. Port V I/O Register (PTV)
Read: Anytime. Write: anytime.
If the associated data direction bit (DDRVx) is set to 1 (output), a read returns the value of the I/O register
bit.
If the associated data direction bit (DDRVx) is set to 0 (input) and the slew rate is enabled, the associated
I/O register bit (PTVx) reads “1”.
If the associated data direction bit (DDRVx) is set to 0 (input) and the slew rate is disabled, a read returns
the value of the pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
156
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.8.2
R
Port V Input Register (PTIV)
7
6
5
4
3
2
1
0
PTIV7
PTIV6
PTIV5
PTIV4
PTIV3
PTIV2
PTIV1
PTIV0
u
u
u
u
u
u
u
u
W
Reset
= Reserved or Unimplemented
u = Unaffected by reset
Figure 4-50. Port V Input Register (PTIV)
Read: Anytime. Write: Never, writes to this register have no effect.
If the associated slew rate control is enabled (digital input buffer is disabled), a read returns a “1”. If the
associated slew rate control is disabled (digital input buffer is enabled), a read returns the status of the
associated pin.
4.3.8.3
Port V Data Direction Register (DDRV)
7
6
5
4
3
2
1
0
DDRV7
DDRV6
DDRV5
DDRV4
DDRV3
DDRV2
DDRV1
DDRV0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-51. Port V Data Direction Register (DDRV)
Read: Anytime. Write: Anytime.
This register configures port pins PV[7:0] as either input or output.
When enabled, the SSD or MC modules force the I/O state to be an output for each associated pin and the
associated Data Direction Register bit has no effect. If the SSD and MC modules are disabled, the
corresponding Data Direction Register bits revert to control the I/O direction of the associated pins.
Table 4-36. DDRV Field Descriptions
Field
7:0
DDRV[7:0]
Description
Data Direction Port V
0 Associated pin is configured as input.
1 Associated pin is configured as output.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
157
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.8.4
Port V Slew Rate Register (SRRV)
7
6
5
4
3
2
1
0
SRRV7
SRRV6
SRRV5
SRRV4
SRRV3
SRRV2
SRRV1
SRRV0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-52. Port V Slew Rate Register (SRRV)
Read: anytime. Write: Anytime.
This register enables the slew rate control and disables the digital input buffer for port pins PV[7:0].
Table 4-37. SRRV Field Descriptions
Field
7:0
SRRV[7:0]
4.3.8.5
Description
Slew Rate Port V
0 Disables slew rate control and enables digital input buffer.
1 Enables slew rate control and disables digital input buffer.
Port V Pull Device Enable Register (PERV)
7
6
5
4
3
2
1
0
PERV7
PERV6
PERV5
PERV4
PERV3
PERV2
PERV1
PERV0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-53. Port V Pull Device Enable Register (PERV)
Read: Anytime. Write: Anytime.
This register configures whether a pull-up or a pull-down device is activated on configured input pins. If
a pin is configured as output, the corresponding Pull Device Enable Register bit has no effect.
Table 4-38. PERV Field Descriptions
Field
7:0
PERV[7:0]
Description
Pull Device Enable Port V
0 Pull-up or pull-down device is disabled.
1 Pull-up or pull-down device is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
158
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.3.8.6
Port V Polarity Select Register (PPSV)
7
6
5
4
3
2
1
0
PPSV7
PPSV6
PPSV5
PPSV4
PPSV3
PPSV2
PPSV1
PPSV0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 4-54. Port V Polarity Select Register (PPSV)
Read: Anytime. Write: Anytime.
The Port V Polarity Select Register selects whether a pull-down or a pull-up device is connected to the pin.
The Port V Polarity Select Register is effective only when the corresponding Data Direction Register bit
is set to 0 (input) and the corresponding Pull Device Enable Register bit is set to 1.
Table 4-39. PPSV Field Descriptions
Field
7:0
PPSV[7:0]
Description
Pull Select Port V
0 A pull-up device is connected to the associated port V pin.
1 A pull-down device is connected to the associated port V pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
159
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.4
Functional Description
Each pin associated with ports AD, L, P, S, T, U and V can act as general-purpose I/O. In addition the pin
can act as an output from a peripheral module or an input to a peripheral module.
A set of configuration registers is common to all ports. All registers can be written at any time, however a
specific configuration might not become active.
Example: Selecting a pull-up resistor. This resistor does not become active while the port is used
as a push-pull output.
4.4.1
I/O Register
The I/O Register holds the value driven out to the pin if the port is used as a general-purpose I/O. Writing
to the I/O Register only has an effect on the pin if the port is used as general-purpose output.
When reading the I/O Register, the value of each pin is returned if the corresponding Data Direction
Register bit is set to 0 (pin configured as input). If the data direction register bits is set to 1, the content of
the I/O Register bit is returned. This is independent of any other configuration (Figure 4-55).
Due to internal synchronization circuits, it can take up to 2 bus cycles until the correct value is read on the
I/O Register when changing the data direction register.
4.4.2
Input Register
The Input Register is a read-only register and generally returns the value of the pin (Figure 4-55). It can
be used to detect overload or short circuit conditions.
Due to internal synchronization circuits, it can take up to 2 bus cycles until the correct value is read on the
Input Register when changing the Data Direction Register.
4.4.3
Data Direction Register
The Data Direction Register defines whether the pin is used as an input or an output. A Data Direction
Register bit set to 0 configures the pin as an input. A Data Direction Register bit set to 0 configures the pin
as an output. If a peripheral module controls the pin the contents of the data direction register is ignored
(Figure 4-55).
MC9S12HZ256 Data Sheet, Rev. 2.04
160
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
PTIx
0
1
PTx
PAD
0
1
DDRx
0
1
Digital
Module
data out
output enable
module enable
Figure 4-55. Illustration of I/O Pin Functionality
Figure 4-56 shows the state of digital inputs and outputs when an analog module drives the port. When the
analog module is enabled all associated digital output ports are disabled and all associated digital input
ports read “1”.
1
Digital
Input
1
0
Module
Enable
Analog
Module
Digital
Output
Analog
Output
0
PAD
1
PIM Boundary
Figure 4-56. Digital Ports and Analog Module
4.4.4
Reduced Drive Register
If the port is used as an output the Reduced Drive Register allows the configuration of the drive strength.
4.4.5
Pull Device Enable Register
The Pull Device Enable Register turns on a pull-up or pull-down device. The pull device becomes active
only if the pin is used as an input or as a wired-or output.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
161
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.4.6
Polarity Select Register
The Polarity Select Register selects either a pull-up or pull-down device if enabled. The pull device
becomes active only if the pin is used as an input or as a wired-or output.
4.4.7
Pin Configuration Summary
The following table summarizes the effect of various configuration in the Data Direction (DDR),
Input/Output (I/O), reduced drive (RDR), Pull Enable (PE), Pull Select (PS) and Interrupt Enable (IE)
register bits. The PS configuration bit is used for two purposes:
1. Configure the sensitive interrupt edge (rising or falling), if interrupt is enabled.
2. Select either a pull-up or pull-down device if PE is set to “1”.
Table 4-40. Pin Configuration Summary
1
2
DDR
IO
RDR
PE
PS
IE1
Function2
Pull Device
Interrupt
0
X
X
0
X
0
Input
Disabled
Disabled
0
X
X
1
0
0
Input
Pull Up
Disabled
0
X
X
1
1
0
Input
Pull Down
Disabled
0
X
X
0
0
1
Input
Disabled
Falling Edge
0
X
X
0
1
1
Input
Disabled
Rising Edge
0
X
X
1
0
1
Input
Pull Up
Falling Edge
0
X
X
1
1
1
Input
Pull Down
Rising Edge
1
0
0
X
X
0
Output to 0, Full Drive
Disabled
Disabled
1
1
0
X
X
0
Output to 1, Full Drive
Disabled
Disabled
1
0
1
X
X
0
Output to 0, Reduced Drive
Disabled
Disabled
1
1
1
X
X
0
Output to 1, Reduced Drive
Disabled
Disabled
1
0
0
X
0
1
Output to 0, Full Drive
Disabled
Falling Edge
1
1
0
X
1
1
Output to 1, Full Drive
Disabled
Rising Edge
1
0
1
X
0
1
Output to 0, Reduced Drive
Disabled
Falling Edge
1
1
1
X
1
1
Output to 1, Reduced Drive
Disabled
Rising Edge
Applicable only on Port AD.
Digital outputs are disabled and digital input logic is forced to “1” when an analog module associated with the port is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
162
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.5
Resets
The reset values of all registers are given in the register description in Section 4.3, “Memory Map and
Register Definition”.
All ports start up as general-purpose inputs on reset.
4.5.1
Reset Initialization
All registers including the data registers get set/reset asynchronously. Table 4-41 summarizes the port
properties after reset initialization.
P
Table 4-41. Port Reset State Summary
Reset States
Port
A
B
E
1
Data
Direction
Refer to
section Bus
Control and
Input/Output
Pull Mode
Red. Drive/
Slew Rate
Wired-OR
Mode
Pull Down
Refer to section Bus Control and Input/Output
Interrupt
Pull Down
Pull Down1
K
Pull Down
BKGD pin
Pull Down
T
Input
Pull Down
Disabled
N/A
N/A
S
Input
Hi-z
Disabled
Disabled
N/A
M
Input
Hi-z
Disabled
Disabled
N/A
P
Input
Hi-z
Disabled
N/A
N/A
L
Input
Pull Down
Disabled
N/A
N/A
U
Input
Hi-z
Disabled
N/A
N/A
V
Input
Hi-z
Disabled
N/A
N/A
AD
Input
Hi-z
Disabled
N/A
Disabled
PE[1:0] pins have pull-ups instead of pull-downs.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
163
Chapter 4 Port Integration Module (PIM9HZ256V2)
4.6
4.6.1
Interrupts
General
Port AD generates an edge sensitive interrupt if enabled. It offers eight I/O pins with edge triggered
interrupt capability in wired-or fashion. The interrupt enable as well as the sensitivity to rising or falling
edges can be individually configured on per pin basis. All eight bits/pins share the same interrupt vector.
Interrupts can be used with the pins configured as inputs (with the corresponding ATDDIEN1 bit set to 1)
or outputs.
An interrupt is generated when a bit in the port interrupt flag register and its corresponding port interrupt
enable bit are both set. This external interrupt feature is capable to wake up the CPU when it is in stop or
wait mode.
A digital filter on each pin prevents pulses (Figure 4-58) shorter than a specified time from generating an
interrupt. The minimum time varies over process conditions, temperature and voltage (Figure 4-57 and
Table 4-42).
Glitch, filtered out, no interrupt flag set
Valid pulse, interrupt flag set
tifmin
tifmax
Figure 4-57. Interrupt Glitch Filter on Port AD (PPS = 0)
Table 4-42. Pulse Detection Criteria
Mode
Pulse
STOP1
STOP
Unit
Ignored
Uncertain
Valid
1
tpulse <= 3
3 < tpulse
<4
tpulse >= 4
Bus Clock
Bus Clock
Bus Clock
Unit
tpulse <= 3.2
3.2 < tpulse
< 10
tpulse >= 10
µs
µs
µs
These values include the spread of the oscillator frequency over temperature,
voltage and process.
MC9S12HZ256 Data Sheet, Rev. 2.04
164
Freescale Semiconductor
Chapter 4 Port Integration Module (PIM9HZ256V2)
tpulse
Figure 4-58. Pulse Illustration
A valid edge on an input is detected if 4 consecutive samples of a passive level are followed by 4
consecutive samples of an active level directly or indirectly
The filters are continuously clocked by the bus clock in RUN and WAIT mode. In STOP mode the clock
is generated by a single RC oscillator in the port integration module. To maximize current saving the RC
oscillator runs only if the following condition is true on any pin:
Sample count <= 4 and port interrupt enabled (PIE=1) and port interrupt flag not set (PIF=0).
4.6.2
Interrupt Sources
Table 4-43. Port Integration Module Interrupt Sources
Interrupt
Source
Interrupt
Flag
Local
Enable
Global (CCR)
Mask
Port AD
PIFAD[7:0]
PIEAD[7:0]
I Bit
NOTE
Vector addresses and their relative interrupt priority are determined at the
MCU level.
4.6.3
Operation in Stop Mode
All clocks are stopped in STOP mode. The port integration module has asynchronous paths on port AD to
generate wake-up interrupts from stop mode. For other sources of external interrupts refer to the respective
block description chapters.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
165
Chapter 4 Port Integration Module (PIM9HZ256V2)
MC9S12HZ256 Data Sheet, Rev. 2.04
166
Freescale Semiconductor
Chapter 5
Clocks and Reset Generator (CRGV4)
5.1
Introduction
This specification describes the function of the clocks and reset generator (CRG).
5.1.1
Features
The main features of this block are:
• Phase-locked loop (PLL) frequency multiplier
— Reference divider
— Automatic bandwidth control mode for low-jitter operation
— Automatic frequency lock detector
— CPU interrupt on entry or exit from locked condition
— Self-clock mode in absence of reference clock
• System clock generator
— Clock quality check
— Clock switch for either oscillator- or PLL-based system clocks
— User selectable disabling of clocks during wait mode for reduced power consumption
• Computer operating properly (COP) watchdog timer with time-out clear window
• System reset generation from the following possible sources:
— Power-on reset
— Low voltage reset
Refer to the device overview section for availability of this feature.
— COP reset
— Loss of clock reset
— External pin reset
• Real-time interrupt (RTI)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
167
Chapter 5 Clocks and Reset Generator (CRGV4)
5.1.2
Modes of Operation
This subsection lists and briefly describes all operating modes supported by the CRG.
• Run mode
All functional parts of the CRG are running during normal run mode. If RTI or COP functionality
is required the individual bits of the associated rate select registers (COPCTL, RTICTL) have to be
set to a nonzero value.
• Wait mode
This mode allows to disable the system and core clocks depending on the configuration of the
individual bits in the CLKSEL register.
• Stop mode
Depending on the setting of the PSTP bit, stop mode can be differentiated between full stop mode
(PSTP = 0) and pseudo-stop mode (PSTP = 1).
— Full stop mode
The oscillator is disabled and thus all system and core clocks are stopped. The COP and the
RTI remain frozen.
— Pseudo-stop mode
The oscillator continues to run and most of the system and core clocks are stopped. If the
respective enable bits are set the COP and RTI will continue to run, else they remain frozen.
• Self-clock mode
Self-clock mode will be entered if the clock monitor enable bit (CME) and the self-clock mode
enable bit (SCME) are both asserted and the clock monitor in the oscillator block detects a loss of
clock. As soon as self-clock mode is entered the CRG starts to perform a clock quality check.
Self-clock mode remains active until the clock quality check indicates that the required quality of
the incoming clock signal is met (frequency and amplitude). Self-clock mode should be used for
safety purposes only. It provides reduced functionality to the MCU in case a loss of clock is causing
severe system conditions.
5.1.3
Block Diagram
Figure 5-1 shows a block diagram of the CRG.
MC9S12HZ256 Data Sheet, Rev. 2.04
168
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Voltage
Regulator
Power-on Reset
Low Voltage Reset 1
CRG
RESET
CM fail
Clock
Monitor
OSCCLK
EXTAL
Oscillator
XTAL
COP Timeout
XCLKS
Reset
Generator
Clock Quality
Checker
COP
RTI
System Reset
Bus Clock
Core Clock
Oscillator Clock
Registers
XFC
VDDPLL
VSSPLL
PLLCLK
PLL
Clock and Reset
Control
Real-Time Interrupt
PLL Lock Interrupt
Self-Clock Mode
Interrupt
1
Refer to the device overview section for availability of the low-voltage reset feature.
Figure 5-1. CRG Block Diagram
5.2
External Signal Description
This section lists and describes the signals that connect off chip.
5.2.1
VDDPLL, VSSPLL — PLL Operating Voltage, PLL Ground
These pins provides operating voltage (VDDPLL) and ground (VSSPLL) for the PLL circuitry. This allows
the supply voltage to the PLL to be independently bypassed. Even if PLL usage is not required VDDPLL
and VSSPLL must be connected properly.
5.2.2
XFC — PLL Loop Filter Pin
A passive external loop filter must be placed on the XFC pin. The filter is a second-order, low-pass filter
to eliminate the VCO input ripple. The value of the external filter network and the reference frequency
determines the speed of the corrections and the stability of the PLL. Refer to the device overview chapter
for calculation of PLL loop filter (XFC) components. If PLL usage is not required the XFC pin must be
tied to VDDPLL.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
169
Chapter 5 Clocks and Reset Generator (CRGV4)
VDDPLL
CS
CP
MCU
RS
XFC
Figure 5-2. PLL Loop Filter Connections
5.2.3
RESET — Reset Pin
RESET is an active low bidirectional reset pin. As an input it initializes the MCU asynchronously to a
known start-up state. As an open-drain output it indicates that an system reset (internal to MCU) has been
triggered.
5.3
Memory Map and Register Definition
This section provides a detailed description of all registers accessible in the CRG.
5.3.1
Module Memory Map
Table 5-1 gives an overview on all CRG registers.
Table 5-1. CRG Memory Map
Address
Offset
Use
Access
0x0000
CRG Synthesizer Register (SYNR)
R/W
0x0001
CRG Reference Divider Register (REFDV)
R/W
(CTFLG)1
0x0002
CRG Test Flags Register
R/W
0x0003
CRG Flags Register (CRGFLG)
R/W
0x0004
CRG Interrupt Enable Register (CRGINT)
R/W
0x0005
CRG Clock Select Register (CLKSEL)
R/W
0x0006
CRG PLL Control Register (PLLCTL)
R/W
0x0007
CRG RTI Control Register (RTICTL)
R/W
0x0008
CRG COP Control Register (COPCTL)
(FORBYP)2
0x0009
CRG Force and Bypass Test Register
0x000A
CRG Test Control Register
(CTCTL)3
0x000B
CRG COP Arm/Timer Reset (ARMCOP)
R/W
R/W
R/W
R/W
1
CTFLG is intended for factory test purposes only.
FORBYP is intended for factory test purposes only.
3
CTCTL is intended for factory test purposes only.
2
MC9S12HZ256 Data Sheet, Rev. 2.04
170
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
NOTE
Register address = base address + address offset, where the base address is
defined at the MCU level and the address offset is defined at the module
level.
5.3.2
Register Descriptions
This section describes in address order all the CRG registers and their individual bits.
Register
Name
SYNR
R
Bit 7
6
5
4
3
2
1
Bit 0
0
0
SYN5
SYN4
SYN3
SYN2
SYN1
SYN0
0
0
0
0
REFDV3
REFDV2
REFDV1
REFDV0
0
0
0
0
0
0
0
0
RTIF
PORF
LVRF
LOCKIF
LOCK
TRACK
0
0
0
0
PLLSEL
PSTP
SYSWAI
ROAWAI
PLLWAI
CWAI
RTIWAI
COPWAI
CME
PLLON
AUTO
ACQ
PRE
PCE
SCME
RTR6
RTR5
RTR4
RTR3
RTR2
RTR1
RTR0
0
0
0
CR2
CR1
CR0
W
REFDV
R
W
CTFLG
R
W
CRGFLG
R
W
CRGINT
R
W
CLKSEL
R
W
PLLCTL
R
W
RTICTL
R
RTIE
0
W
COPCTL
R
W
FORBYP
R
LOCKIE
0
SCMIF
SCMIE
SCM
0
WCOP
RSBCK
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
CTCTL
R
W
= Unimplemented or Reserved
Figure 5-3. CRG Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
171
Chapter 5 Clocks and Reset Generator (CRGV4)
Register
Name
ARMCOP
Bit 7
6
5
4
3
2
1
Bit 0
R
0
0
0
0
0
0
0
0
W
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
= Unimplemented or Reserved
Figure 5-3. CRG Register Summary (continued)
5.3.2.1
CRG Synthesizer Register (SYNR)
The SYNR register controls the multiplication factor of the PLL. If the PLL is on, the count in the loop
divider (SYNR) register effectively multiplies up the PLL clock (PLLCLK) from the reference frequency
by 2 x (SYNR+1). PLLCLK will not be below the minimum VCO frequency (fSCM).
( SYNR + 1 )
PLLCLK = 2xOSCCLKx ----------------------------------( REFDV + 1 )
NOTE
If PLL is selected (PLLSEL=1), Bus Clock = PLLCLK / 2
Bus Clock must not exceed the maximum operating system frequency.
R
7
6
0
0
5
4
3
2
1
0
SYN5
SYNR
SYN3
SYN2
SYN1
SYN0
0
0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 5-4. CRG Synthesizer Register (SYNR)
Read: anytime
Write: anytime except if PLLSEL = 1
NOTE
Write to this register initializes the lock detector bit and the track detector
bit.
MC9S12HZ256 Data Sheet, Rev. 2.04
172
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
5.3.2.2
CRG Reference Divider Register (REFDV)
The REFDV register provides a finer granularity for the PLL multiplier steps. The count in the reference
divider divides OSCCLK frequency by REFDV + 1.
R
7
6
5
4
0
0
0
0
3
2
1
0
REFDV3
REFDV2
REFDV1
REFDV0
0
0
0
0
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 5-5. CRG Reference Divider Register (REFDV)
Read: anytime
Write: anytime except when PLLSEL = 1
NOTE
Write to this register initializes the lock detector bit and the track detector
bit.
5.3.2.3
Reserved Register (CTFLG)
This register is reserved for factory testing of the CRG module and is not available in normal modes.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 5-6. CRG Reserved Register (CTFLG)
Read: always reads 0x0000 in normal modes
Write: unimplemented in normal modes
NOTE
Writing to this register when in special mode can alter the CRG
functionality.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
173
Chapter 5 Clocks and Reset Generator (CRGV4)
5.3.2.4
CRG Flags Register (CRGFLG)
This register provides CRG status bits and flags.
7
6
5
4
RTIF
PORF
LVRF
LOCKIF
0
Note 1
Note 2
0
R
3
2
LOCK
TRACK
1
0
SCM
SCMIF
W
Reset
0
0
0
0
1. PORF is set to 1 when a power-on reset occurs. Unaffected by system reset.
2. LVRF is set to 1 when a low-voltage reset occurs. Unaffected by system reset.
= Unimplemented or Reserved
Figure 5-7. CRG Flag Register (CRGFLG)
Read: anytime
Write: refer to each bit for individual write conditions
Table 5-2. CRGFLG Field Descriptions
Field
Description
7
RTIF
Real-Time Interrupt Flag — RTIF is set to 1 at the end of the RTI period. This flag can only be cleared by writing
a 1. Writing a 0 has no effect. If enabled (RTIE = 1), RTIF causes an interrupt request.
0 RTI time-out has not yet occurred.
1 RTI time-out has occurred.
6
PORF
Power-on Reset Flag — PORF is set to 1 when a power-on reset occurs. This flag can only be cleared by writing
a 1. Writing a 0 has no effect.
0 Power-on reset has not occurred.
1 Power-on reset has occurred.
5
LVRF
Low-Voltage Reset Flag — If low voltage reset feature is not available (see the device overview chapter), LVRF
always reads 0. LVRF is set to 1 when a low voltage reset occurs. This flag can only be cleared by writing a 1.
Writing a 0 has no effect.
0 Low voltage reset has not occurred.
1 Low voltage reset has occurred.
4
LOCKIF
PLL Lock Interrupt Flag — LOCKIF is set to 1 when LOCK status bit changes. This flag can only be cleared by
writing a 1. Writing a 0 has no effect.If enabled (LOCKIE = 1), LOCKIF causes an interrupt request.
0 No change in LOCK bit.
1 LOCK bit has changed.
3
LOCK
Lock Status Bit — LOCK reflects the current state of PLL lock condition. This bit is cleared in self-clock mode.
Writes have no effect.
0 PLL VCO is not within the desired tolerance of the target frequency.
1 PLL VCO is within the desired tolerance of the target frequency.
2
TRACK
Track Status Bit — TRACK reflects the current state of PLL track condition. This bit is cleared in self-clock mode.
Writes have no effect.
0 Acquisition mode status.
1 Tracking mode status.
MC9S12HZ256 Data Sheet, Rev. 2.04
174
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-2. CRGFLG Field Descriptions (continued)
Field
1
SCMIF
0
SCM
5.3.2.5
Description
Self-Clock Mode Interrupt Flag — SCMIF is set to 1 when SCM status bit changes. This flag can only be
cleared by writing a 1. Writing a 0 has no effect. If enabled (SCMIE=1), SCMIF causes an interrupt request.
0 No change in SCM bit.
1 SCM bit has changed.
Self-Clock Mode Status Bit — SCM reflects the current clocking mode. Writes have no effect.
0 MCU is operating normally with OSCCLK available.
1 MCU is operating in self-clock mode with OSCCLK in an unknown state. All clocks are derived from PLLCLK
running at its minimum frequency fSCM.
CRG Interrupt Enable Register (CRGINT)
This register enables CRG interrupt requests.
7
R
6
5
0
0
RTIE
4
3
2
0
0
LOCKIE
1
0
0
SCMIE
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 5-8. CRG Interrupt Enable Register (CRGINT)
Read: anytime
Write: anytime
Table 5-3. CRGINT Field Descriptions
Field
7
RTIE
Description
Real-Time Interrupt Enable Bit
0 Interrupt requests from RTI are disabled.
1 Interrupt will be requested whenever RTIF is set.
4
LOCKIE
Lock Interrupt Enable Bit
0 LOCK interrupt requests are disabled.
1 Interrupt will be requested whenever LOCKIF is set.
1
SCMIE
Self-Clock Mode Interrupt Enable Bit
0 SCM interrupt requests are disabled.
1 Interrupt will be requested whenever SCMIF is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
175
Chapter 5 Clocks and Reset Generator (CRGV4)
5.3.2.6
CRG Clock Select Register (CLKSEL)
This register controls CRG clock selection. Refer to Figure 5-17 for details on the effect of each bit.
7
6
5
4
3
2
1
0
PLLSEL
PSTP
SYSWAI
ROAWAI
PLLWAI
CWAI
RTIWAI
COPWAI
0
0
0
0
0
0
0
0
R
W
Reset
Figure 5-9. CRG Clock Select Register (CLKSEL)
Read: anytime
Write: refer to each bit for individual write conditions
Table 5-4. CLKSEL Field Descriptions
Field
Description
7
PLLSEL
PLL Select Bit — Write anytime. Writing a 1 when LOCK = 0 and AUTO = 1, or TRACK = 0 and AUTO = 0 has
no effect. This prevents the selection of an unstable PLLCLK as SYSCLK. PLLSEL bit is cleared when the MCU
enters self-clock mode, stop mode or wait mode with PLLWAI bit set.
0 System clocks are derived from OSCCLK (Bus Clock = OSCCLK / 2).
1 System clocks are derived from PLLCLK (Bus Clock = PLLCLK / 2).
6
PSTP
Pseudo-Stop Bit — Write: anytime — This bit controls the functionality of the oscillator during stop mode.
0 Oscillator is disabled in stop mode.
1 Oscillator continues to run in stop mode (pseudo-stop). The oscillator amplitude is reduced. Refer to oscillator
block description for availability of a reduced oscillator amplitude.
Note: Pseudo-stop allows for faster stop recovery and reduces the mechanical stress and aging of the resonator
in case of frequent stop conditions at the expense of a slightly increased power consumption.
Note: Lower oscillator amplitude exhibits lower power consumption but could have adverse effects during any
electro-magnetic susceptibility (EMS) tests.
5
SYSWAI
System Clocks Stop in Wait Mode Bit — Write: anytime
0 In wait mode, the system clocks continue to run.
1 In wait mode, the system clocks stop.
Note: RTI and COP are not affected by SYSWAI bit.
4
ROAWAI
Reduced Oscillator Amplitude in Wait Mode Bit — Write: anytime — Refer to oscillator block description
chapter for availability of a reduced oscillator amplitude. If no such feature exists in the oscillator block then
setting this bit to 1 will not have any effect on power consumption.
0 Normal oscillator amplitude in wait mode.
1 Reduced oscillator amplitude in wait mode.
Note: Lower oscillator amplitude exhibits lower power consumption but could have adverse effects during any
electro-magnetic susceptibility (EMS) tests.
3
PLLWAI
PLL Stops in Wait Mode Bit — Write: anytime — If PLLWAI is set, the CRG will clear the PLLSEL bit before
entering wait mode. The PLLON bit remains set during wait mode but the PLL is powered down. Upon exiting
wait mode, the PLLSEL bit has to be set manually if PLL clock is required.
While the PLLWAI bit is set the AUTO bit is set to 1 in order to allow the PLL to automatically lock on the selected
target frequency after exiting wait mode.
0 PLL keeps running in wait mode.
1 PLL stops in wait mode.
2
CWAI
Core Stops in Wait Mode Bit — Write: anytime
0 Core clock keeps running in wait mode.
1 Core clock stops in wait mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
176
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-4. CLKSEL Field Descriptions (continued)
Field
Description
1
RTIWAI
RTI Stops in Wait Mode Bit — Write: anytime
0 RTI keeps running in wait mode.
1 RTI stops and initializes the RTI dividers whenever the part goes into wait mode.
0
COPWAI
COP Stops in Wait Mode Bit — Normal modes: Write once —Special modes: Write anytime
0 COP keeps running in wait mode.
1 COP stops and initializes the COP dividers whenever the part goes into wait mode.
5.3.2.7
CRG PLL Control Register (PLLCTL)
This register controls the PLL functionality.
7
6
5
4
CME
PLLON
AUTO
ACQ
1
1
1
1
3
R
2
1
0
PRE
PCE
SCME
0
0
1
0
W
Reset
0
= Unimplemented or Reserved
Figure 5-10. CRG PLL Control Register (PLLCTL)
Read: anytime
Write: refer to each bit for individual write conditions
Table 5-5. PLLCTL Field Descriptions
Field
Description
7
CME
Clock Monitor Enable Bit — CME enables the clock monitor. Write anytime except when SCM = 1.
0 Clock monitor is disabled.
1 Clock monitor is enabled. Slow or stopped clocks will cause a clock monitor reset sequence or self-clock
mode.
Note: Operating with CME = 0 will not detect any loss of clock. In case of poor clock quality this could cause
unpredictable operation of the MCU.
Note: In Stop Mode (PSTP = 0) the clock monitor is disabled independently of the CME bit setting and any loss
of clock will not be detected.
6
PLLON
Phase Lock Loop On Bit — PLLON turns on the PLL circuitry. In self-clock mode, the PLL is turned on, but the
PLLON bit reads the last latched value. Write anytime except when PLLSEL = 1.
0 PLL is turned off.
1 PLL is turned on. If AUTO bit is set, the PLL will lock automatically.
5
AUTO
Automatic Bandwidth Control Bit — AUTO selects either the high bandwidth (acquisition) mode or the low
bandwidth (tracking) mode depending on how close to the desired frequency the VCO is running. Write anytime
except when PLLWAI=1, because PLLWAI sets the AUTO bit to 1.
0 Automatic mode control is disabled and the PLL is under software control, using ACQ bit.
1 Automatic mode control is enabled and ACQ bit has no effect.
4
ACQ
Acquisition Bit — Write anytime. If AUTO=1 this bit has no effect.
0 Low bandwidth filter is selected.
1 High bandwidth filter is selected.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
177
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-5. PLLCTL Field Descriptions (continued)
Field
Description
2
PRE
RTI Enable during Pseudo-Stop Bit — PRE enables the RTI during pseudo-stop mode. Write anytime.
0 RTI stops running during pseudo-stop mode.
1 RTI continues running during pseudo-stop mode.
Note: If the PRE bit is cleared the RTI dividers will go static while pseudo-stop mode is active. The RTI dividers
will not initialize like in wait mode with RTIWAI bit set.
1
PCE
COP Enable during Pseudo-Stop Bit — PCE enables the COP during pseudo-stop mode. Write anytime.
0 COP stops running during pseudo-stop mode
1 COP continues running during pseudo-stop mode
Note: If the PCE bit is cleared the COP dividers will go static while pseudo-stop mode is active. The COP dividers
will not initialize like in wait mode with COPWAI bit set.
0
SCME
Self-Clock Mode Enable Bit — Normal modes: Write once —Special modes: Write anytime — SCME can not
be cleared while operating in self-clock mode (SCM=1).
0 Detection of crystal clock failure causes clock monitor reset (see Section 5.5.1, “Clock Monitor Reset”).
1 Detection of crystal clock failure forces the MCU in self-clock mode (see Section 5.4.7.2, “Self-Clock Mode”).
5.3.2.8
CRG RTI Control Register (RTICTL)
This register selects the timeout period for the real-time interrupt.
7
R
6
5
4
3
2
1
0
RTR6
RTR5
RTR4
RTR3
RTR2
RTR1
RTR0
0
0
0
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 5-11. CRG RTI Control Register (RTICTL)
Read: anytime
Write: anytime
NOTE
A write to this register initializes the RTI counter.
Table 5-6. RTICTL Field Descriptions
Field
Description
6:4
RTR[6:4]
Real-Time Interrupt Prescale Rate Select Bits — These bits select the prescale rate for the RTI. See Table 5-7.
3:0
RTR[3:0]
Real-Time Interrupt Modulus Counter Select Bits — These bits select the modulus counter target value to
provide additional granularity. Table 5-7 shows all possible divide values selectable by the RTICTL register. The
source clock for the RTI is OSCCLK.
MC9S12HZ256 Data Sheet, Rev. 2.04
178
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-7. RTI Frequency Divide Rates
RTR[6:4] =
RTR[3:0]
000
(OFF)
001
(210)
010
(211)
011
(212)
100
(213)
101
(214)
110
(215)
111
(216)
0000 (÷1)
OFF*
210
211
212
213
214
215
216
0001 (÷2)
OFF*
2x210
2x211
2x212
2x213
2x214
2x215
2x216
0010 (÷3)
OFF*
3x210
3x211
3x212
3x213
3x214
3x215
3x216
0011 (÷4)
OFF*
4x210
4x211
4x212
4x213
4x214
4x215
4x216
0100 (÷5)
OFF*
5x210
5x211
5x212
5x213
5x214
5x215
5x216
0101 (÷6)
OFF*
6x210
6x211
6x212
6x213
6x214
6x215
6x216
0110 (÷7)
OFF*
7x210
7x211
7x212
7x213
7x214
7x215
7x216
0111 (÷8)
OFF*
8x210
8x211
8x212
8x213
8x214
8x215
8x216
1000 (÷9)
OFF*
9x210
9x211
9x212
9x213
9x214
9x215
9x216
1001 (÷10)
OFF*
10x210
10x211
10x212
10x213
10x214
10x215
10x216
1010 (÷11)
OFF*
11x210
11x211
11x212
11x213
11x214
11x215
11x216
1011 (÷12)
OFF*
12x210
12x211
12x212
12x213
12x214
12x215
12x216
1100 (÷ 13)
OFF*
13x210
13x211
13x212
13x213
13x214
13x215
13x216
1101 (÷14)
OFF*
14x210
14x211
14x212
14x213
14x214
14x215
14x216
1110 (÷15)
OFF*
15x210
15x211
15x212
15x213
15x214
15x215
15x216
1111 (÷ 16)
OFF*
16x210
16x211
16x212
16x213
16x214
16x215
16x216
* Denotes the default value out of reset.This value should be used to disable the RTI to ensure future backwards compatibility.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
179
Chapter 5 Clocks and Reset Generator (CRGV4)
5.3.2.9
CRG COP Control Register (COPCTL)
This register controls the COP (computer operating properly) watchdog.
7
6
WCOP
RSBCK
0
0
R
5
4
3
0
0
0
2
1
0
CR2
CR1
CR0
0
0
0
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 5-12. CRG COP Control Register (COPCTL)
Read: anytime
Write: WCOP, CR2, CR1, CR0: once in user mode, anytime in special mode
Write: RSBCK: once
Table 5-8. COPCTL Field Descriptions
Field
Description
7
WCOP
Window COP Mode Bit — When set, a write to the ARMCOP register must occur in the last 25% of the selected
period. A write during the first 75% of the selected period will reset the part. As long as all writes occur during
this window, 0x0055 can be written as often as desired. As soon as 0x00AA is written after the 0x0055, the
time-out logic restarts and the user must wait until the next window before writing to ARMCOP. Table 5-9 shows
the exact duration of this window for the seven available COP rates.
0 Normal COP operation
1 Window COP operation
6
RSBCK
COP and RTI Stop in Active BDM Mode Bit
0 Allows the COP and RTI to keep running in active BDM mode.
1 Stops the COP and RTI counters whenever the part is in active BDM mode.
2:0
CR[2:0]
COP Watchdog Timer Rate Select — These bits select the COP time-out rate (see Table 5-9). The COP
time-out period is OSCCLK period divided by CR[2:0] value. Writing a nonzero value to CR[2:0] enables the COP
counter and starts the time-out period. A COP counter time-out causes a system reset. This can be avoided by
periodically (before time-out) reinitializing the COP counter via the ARMCOP register.
Table 5-9. COP Watchdog Rates1
1
CR2
CR1
CR0
OSCCLK
Cycles to Time Out
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
COP disabled
214
216
218
220
222
223
224
OSCCLK cycles are referenced from the previous COP time-out reset
(writing 0x0055/0x00AA to the ARMCOP register)
MC9S12HZ256 Data Sheet, Rev. 2.04
180
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
5.3.2.10
Reserved Register (FORBYP)
NOTE
This reserved register is designed for factory test purposes only, and is not
intended for general user access. Writing to this register when in special
modes can alter the CRG’s functionality.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 5-13. Reserved Register (FORBYP)
Read: always read 0x0000 except in special modes
Write: only in special modes
5.3.2.11
Reserved Register (CTCTL)
NOTE
This reserved register is designed for factory test purposes only, and is not
intended for general user access. Writing to this register when in special test
modes can alter the CRG’s functionality.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 5-14. Reserved Register (CTCTL)
Read: always read 0x0080 except in special modes
Write: only in special modes
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
181
Chapter 5 Clocks and Reset Generator (CRGV4)
5.3.2.12
CRG COP Timer Arm/Reset Register (ARMCOP)
This register is used to restart the COP time-out period.
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
W
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
Reset
Figure 5-15. ARMCOP Register Diagram
Read: always reads 0x0000
Write: anytime
When the COP is disabled (CR[2:0] = “000”) writing to this register has no effect.
When the COP is enabled by setting CR[2:0] nonzero, the following applies:
Writing any value other than 0x0055 or 0x00AA causes a COP reset. To restart the COP time-out
period you must write 0x0055 followed by a write of 0x00AA. Other instructions may be executed
between these writes but the sequence (0x0055, 0x00AA) must be completed prior to COP end of
time-out period to avoid a COP reset. Sequences of 0x0055 writes or sequences of 0x00AA writes
are allowed. When the WCOP bit is set, 0x0055 and 0x00AA writes must be done in the last 25%
of the selected time-out period; writing any value in the first 75% of the selected period will cause
a COP reset.
5.4
Functional Description
This section gives detailed informations on the internal operation of the design.
5.4.1
Phase Locked Loop (PLL)
The PLL is used to run the MCU from a different time base than the incoming OSCCLK. For increased
flexibility, OSCCLK can be divided in a range of 1 to 16 to generate the reference frequency. This offers
a finer multiplication granularity. The PLL can multiply this reference clock by a multiple of 2, 4, 6,...
126,128 based on the SYNR register.
[ SYNR + 1 ]
PLLCLK = 2 × OSCCLK × ----------------------------------[ REFDV + 1 ]
CAUTION
Although it is possible to set the two dividers to command a very high clock
frequency, do not exceed the specified bus frequency limit for the MCU.
If (PLLSEL = 1), Bus Clock = PLLCLK / 2
The PLL is a frequency generator that operates in either acquisition mode or tracking mode, depending on
the difference between the output frequency and the target frequency. The PLL can change between
acquisition and tracking modes either automatically or manually.
MC9S12HZ256 Data Sheet, Rev. 2.04
182
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
The VCO has a minimum operating frequency, which corresponds to the self-clock mode frequency fSCM.
REFERENCE
REFDV <3:0>
EXTAL
REDUCED
CONSUMPTION
OSCILLATOR
OSCCLK
FEEDBACK
REFERENCE
PROGRAMMABLE
DIVIDER
XTAL
CRYSTAL
MONITOR
supplied by:
LOOP
PROGRAMMABLE
DIVIDER
LOCK
LOCK
DETECTOR
VDDPLL/VSSPLL
PDET
PHASE
DETECTOR
UP
DOWN
CPUMP
VCO
VDDPLL
LOOP
FILTER
SYN <5:0>
VDDPLL/VSSPLL
XFC
PIN
PLLCLK
VDD/VSS
Figure 5-16. PLL Functional Diagram
5.4.1.1
PLL Operation
The oscillator output clock signal (OSCCLK) is fed through the reference programmable divider and is
divided in a range of 1 to 16 (REFDV+1) to output the reference clock. The VCO output clock, (PLLCLK)
is fed back through the programmable loop divider and is divided in a range of 2 to 128 in increments of
[2 x (SYNR +1)] to output the feedback clock. See Figure 5-16.
The phase detector then compares the feedback clock, with the reference clock. Correction pulses are
generated based on the phase difference between the two signals. The loop filter then slightly alters the DC
voltage on the external filter capacitor connected to XFC pin, based on the width and direction of the
correction pulse. The filter can make fast or slow corrections depending on its mode, as described in the
next subsection. The values of the external filter network and the reference frequency determine the speed
of the corrections and the stability of the PLL.
5.4.1.2
Acquisition and Tracking Modes
The lock detector compares the frequencies of the feedback clock, and the reference clock. Therefore, the
speed of the lock detector is directly proportional to the final reference frequency. The circuit determines
the mode of the PLL and the lock condition based on this comparison.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
183
Chapter 5 Clocks and Reset Generator (CRGV4)
The PLL filter can be manually or automatically configured into one of two possible operating modes:
• Acquisition mode
In acquisition mode, the filter can make large frequency corrections to the VCO. This mode is used
at PLL start-up or when the PLL has suffered a severe noise hit and the VCO frequency is far off
the desired frequency. When in acquisition mode, the TRACK status bit is cleared in the CRGFLG
register.
• Tracking mode
In tracking mode, the filter makes only small corrections to the frequency of the VCO. PLL jitter
is much lower in tracking mode, but the response to noise is also slower. The PLL enters tracking
mode when the VCO frequency is nearly correct and the TRACK bit is set in the CRGFLG register.
The PLL can change the bandwidth or operational mode of the loop filter manually or automatically.
In automatic bandwidth control mode (AUTO = 1), the lock detector automatically switches between
acquisition and tracking modes. Automatic bandwidth control mode also is used to determine when the
PLL clock (PLLCLK) is safe to use as the source for the system and core clocks. If PLL LOCK interrupt
requests are enabled, the software can wait for an interrupt request and then check the LOCK bit. If CPU
interrupts are disabled, software can poll the LOCK bit continuously (during PLL start-up, usually) or at
periodic intervals. In either case, only when the LOCK bit is set, is the PLLCLK clock safe to use as the
source for the system and core clocks. If the PLL is selected as the source for the system and core clocks
and the LOCK bit is clear, the PLL has suffered a severe noise hit and the software must take appropriate
action, depending on the application.
The following conditions apply when the PLL is in automatic bandwidth control mode (AUTO = 1):
• The TRACK bit is a read-only indicator of the mode of the filter.
• The TRACK bit is set when the VCO frequency is within a certain tolerance, ∆trk, and is clear when
the VCO frequency is out of a certain tolerance, ∆unt.
• The LOCK bit is a read-only indicator of the locked state of the PLL.
• The LOCK bit is set when the VCO frequency is within a certain tolerance, ∆Lock, and is cleared
when the VCO frequency is out of a certain tolerance, ∆unl.
• CPU interrupts can occur if enabled (LOCKIE = 1) when the lock condition changes, toggling the
LOCK bit.
The PLL can also operate in manual mode (AUTO = 0). Manual mode is used by systems that do not
require an indicator of the lock condition for proper operation. Such systems typically operate well below
the maximum system frequency (fsys) and require fast start-up. The following conditions apply when in
manual mode:
• ACQ is a writable control bit that controls the mode of the filter. Before turning on the PLL in
manual mode, the ACQ bit should be asserted to configure the filter in acquisition mode.
• After turning on the PLL by setting the PLLON bit software must wait a given time (tacq) before
entering tracking mode (ACQ = 0).
• After entering tracking mode software must wait a given time (tal) before selecting the PLLCLK
as the source for system and core clocks (PLLSEL = 1).
MC9S12HZ256 Data Sheet, Rev. 2.04
184
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
5.4.2
System Clocks Generator
PLLSEL or SCM
WAIT(CWAI,SYSWAI),
STOP
PHASE
LOCK
LOOP
PLLCLK
1
SYSCLK
Core Clock
0
WAIT(SYSWAI),
STOP
÷2
SCM
WAIT(RTIWAI),
STOP(PSTP,PRE),
RTI enable
EXTAL
CLOCK PHASE
GENERATOR
Bus Clock
1
OSCILLATOR
RTI
OSCCLK
0
WAIT(COPWAI),
STOP(PSTP,PCE),
COP enable
XTAL
COP
Clock
Monitor
WAIT(SYSWAI),
STOP
Oscillator
Clock
STOP(PSTP)
Gating
Condition
Oscillator
Clock
(running during
Pseudo-Stop Mode
= Clock Gate
Figure 5-17. System Clocks Generator
The clock generator creates the clocks used in the MCU (see Figure 5-17). The gating condition placed on
top of the individual clock gates indicates the dependencies of different modes (stop, wait) and the setting
of the respective configuration bits.
The peripheral modules use the bus clock. Some peripheral modules also use the oscillator clock. The
memory blocks use the bus clock. If the MCU enters self-clock mode (see Section 5.4.7.2, “Self-Clock
Mode”), oscillator clock source is switched to PLLCLK running at its minimum frequency fSCM. The bus
clock is used to generate the clock visible at the ECLK pin. The core clock signal is the clock for the CPU.
The core clock is twice the bus clock as shown in Figure 5-18. But note that a CPU cycle corresponds to
one bus clock.
PLL clock mode is selected with PLLSEL bit in the CLKSEL register. When selected, the PLL output
clock drives SYSCLK for the main system including the CPU and peripherals. The PLL cannot be turned
off by clearing the PLLON bit, if the PLL clock is selected. When PLLSEL is changed, it takes a maximum
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
185
Chapter 5 Clocks and Reset Generator (CRGV4)
of 4 OSCCLK plus 4 PLLCLK cycles to make the transition. During the transition, all clocks freeze and
CPU activity ceases.
CORE CLOCK:
BUS CLOCK / ECLK
Figure 5-18. Core Clock and Bus Clock Relationship
5.4.3
Clock Monitor (CM)
If no OSCCLK edges are detected within a certain time, the clock monitor within the oscillator block
generates a clock monitor fail event. The CRG then asserts self-clock mode or generates a system reset
depending on the state of SCME bit. If the clock monitor is disabled or the presence of clocks is detected
no failure is indicated by the oscillator block.The clock monitor function is enabled/disabled by the CME
control bit.
5.4.4
Clock Quality Checker
The clock monitor performs a coarse check on the incoming clock signal. The clock quality checker
provides a more accurate check in addition to the clock monitor.
A clock quality check is triggered by any of the following events:
• Power-on reset (POR)
• Low voltage reset (LVR)
• Wake-up from full stop mode (exit full stop)
• Clock monitor fail indication (CM fail)
A time window of 50000 VCO clock cycles1 is called check window.
A number greater equal than 4096 rising OSCCLK edges within a check window is called osc ok. Note that
osc ok immediately terminates the current check window. See Figure 5-19 as an example.
1. VCO clock cycles are generated by the PLL when running at minimum frequency fSCM.
MC9S12HZ256 Data Sheet, Rev. 2.04
186
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
check window
1
VCO
clock
2
50000
49999
3
1 2 3 4 5
4096
OSCCLK
4095
osc ok
Figure 5-19. Check Window Example
The sequence for clock quality check is shown in Figure 5-20.
CM fail
Clock OK
POR
LVR
exit full stop
Clock Monitor Reset
Enter SCM
yes
check window
SCM
active?
num=num+1
yes
osc ok
num=50
no
num=0
no
?
num<50
?
yes
no
SCME=1
?
no
yes
SCM
active?
yes
Switch to OSCCLK
no
Exit SCM
Figure 5-20. Sequence for Clock Quality Check
NOTE
Remember that in parallel to additional actions caused by self-clock mode
or clock monitor reset1 handling the clock quality checker continues to
check the OSCCLK signal.
1. A Clock Monitor Reset will always set the SCME bit to logical’1’
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
187
Chapter 5 Clocks and Reset Generator (CRGV4)
NOTE
The clock quality checker enables the PLL and the voltage regulator
(VREG) anytime a clock check has to be performed. An ongoing clock
quality check could also cause a running PLL (fSCM) and an active VREG
during pseudo-stop mode or wait mode
5.4.5
Computer Operating Properly Watchdog (COP)
WAIT(COPWAI),
STOP(PSTP,PCE),
COP enable
CR[2:0]
0:0:0
CR[2:0]
0:0:1
÷ 16384
OSCCLK
gating condition
= Clock Gate
÷4
0:1:0
÷4
0:1:1
÷4
1:0:0
÷4
1:0:1
÷2
1:1:0
÷2
1:1:1
COP TIMEOUT
Figure 5-21. Clock Chain for COP
The COP (free running watchdog timer) enables the user to check that a program is running and
sequencing properly. The COP is disabled out of reset. When the COP is being used, software is
responsible for keeping the COP from timing out. If the COP times out it is an indication that the software
is no longer being executed in the intended sequence; thus a system reset is initiated (see Section 5.5.2,
“Computer Operating Properly Watchdog (COP) Reset).” The COP runs with a gated OSCCLK (see
Section Figure 5-21., “Clock Chain for COP”). Three control bits in the COPCTL register allow selection
of seven COP time-out periods.
When COP is enabled, the program must write 0x0055 and 0x00AA (in this order) to the ARMCOP
register during the selected time-out period. As soon as this is done, the COP time-out period is restarted.
If the program fails to do this and the COP times out, the part will reset. Also, if any value other than
0x0055 or 0x00AA is written, the part is immediately reset.
Windowed COP operation is enabled by setting WCOP in the COPCTL register. In this mode, writes to
the ARMCOP register to clear the COP timer must occur in the last 25% of the selected time-out period.
A premature write will immediately reset the part.
If PCE bit is set, the COP will continue to run in pseudo-stop mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
188
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
5.4.6
Real-Time Interrupt (RTI)
The RTI can be used to generate a hardware interrupt at a fixed periodic rate. If enabled (by setting
RTIE=1), this interrupt will occur at the rate selected by the RTICTL register. The RTI runs with a gated
OSCCLK (see Section Figure 5-22., “Clock Chain for RTI”). At the end of the RTI time-out period the
RTIF flag is set to 1 and a new RTI time-out period starts immediately.
A write to the RTICTL register restarts the RTI time-out period.
If the PRE bit is set, the RTI will continue to run in pseudo-stop mode.
.
WAIT(RTIWAI),
STOP(PSTP,PRE),
RTI enable
÷ 1024
OSCCLK
RTR[6:4]
0:0:0
0:0:1
÷2
0:1:0
÷2
0:1:1
÷2
1:0:0
÷2
1:0:1
÷2
1:1:0
÷2
1:1:1
gating condition
= Clock Gate
4-BIT MODULUS
COUNTER (RTR[3:0])
RTI TIMEOUT
Figure 5-22. Clock Chain for RTI
5.4.7
5.4.7.1
Modes of Operation
Normal Mode
The CRG block behaves as described within this specification in all normal modes.
5.4.7.2
Self-Clock Mode
The VCO has a minimum operating frequency, fSCM. If the external clock frequency is not available due
to a failure or due to long crystal start-up time, the bus clock and the core clock are derived from the VCO
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
189
Chapter 5 Clocks and Reset Generator (CRGV4)
running at minimum operating frequency; this mode of operation is called self-clock mode. This requires
CME = 1 and SCME = 1. If the MCU was clocked by the PLL clock prior to entering self-clock mode, the
PLLSEL bit will be cleared. If the external clock signal has stabilized again, the CRG will automatically
select OSCCLK to be the system clock and return to normal mode. See Section 5.4.4, “Clock Quality
Checker” for more information on entering and leaving self-clock mode.
NOTE
In order to detect a potential clock loss, the CME bit should be always
enabled (CME=1).
If CME bit is disabled and the MCU is configured to run on PLL clock
(PLLCLK), a loss of external clock (OSCCLK) will not be detected and will
cause the system clock to drift towards the VCO’s minimum frequency
fSCM. As soon as the external clock is available again the system clock
ramps up to its PLL target frequency. If the MCU is running on external
clock any loss of clock will cause the system to go static.
5.4.8
Low-Power Operation in Run Mode
The RTI can be stopped by setting the associated rate select bits to 0.
The COP can be stopped by setting the associated rate select bits to 0.
5.4.9
Low-Power Operation in Wait Mode
The WAI instruction puts the MCU in a low power consumption stand-by mode depending on setting of
the individual bits in the CLKSEL register. All individual wait mode configuration bits can be superposed.
This provides enhanced granularity in reducing the level of power consumption during wait mode.
Table 5-10 lists the individual configuration bits and the parts of the MCU that are affected in wait mode.
Table 5-10. MCU Configuration During Wait Mode
1
PLLWAI
CWAI
SYSWAI
RTIWAI
COPWAI
ROAWAI
PLL
stopped
—
—
—
—
—
Core
—
stopped
stopped
—
—
—
System
—
—
stopped
—
—
—
RTI
—
—
—
stopped
—
—
COP
—
—
—
—
stopped
—
Oscillator
—
—
—
—
—
reduced1
Refer to oscillator block description for availability of a reduced oscillator amplitude.
After executing the WAI instruction the core requests the CRG to switch MCU into wait mode. The CRG
then checks whether the PLLWAI, CWAI and SYSWAI bits are asserted (see Figure 5-23). Depending on
the configuration the CRG switches the system and core clocks to OSCCLK by clearing the PLLSEL bit,
disables the PLL, disables the core clocks and finally disables the remaining system clocks. As soon as all
clocks are switched off wait mode is active.
MC9S12HZ256 Data Sheet, Rev. 2.04
190
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Core req’s
Wait Mode.
PLLWAI=1
?
no
yes
Clear
PLLSEL,
Disable PLL
CWAI or
SYSWAI=1
?
no
yes
Disable
core clocks
SYSWAI=1
?
no
yes
Disable
system clocks
no
Enter
Wait Mode
CME=1
?
Wait Mode left
due to external
reset
no
yes
Exit Wait w.
ext.RESET
CM fail
?
INT
?
yes
no
yes
Exit Wait w.
CMRESET
no
SCME=1
?
yes
SCMIE=1
?
Generate
SCM Interrupt
(Wakeup from Wait)
no
Exit
Wait Mode
yes
Exit
Wait Mode
SCM=1
?
no
yes
Enter
SCM
Enter
SCM
Continue w.
normal OP
Figure 5-23. Wait Mode Entry/Exit Sequence
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
191
Chapter 5 Clocks and Reset Generator (CRGV4)
There are five different scenarios for the CRG to restart the MCU from wait mode:
• External reset
• Clock monitor reset
• COP reset
• Self-clock mode interrupt
• Real-time interrupt (RTI)
If the MCU gets an external reset during wait mode active, the CRG asynchronously restores all
configuration bits in the register space to its default settings and starts the reset generator. After completing
the reset sequence processing begins by fetching the normal reset vector. Wait mode is exited and the MCU
is in run mode again.
If the clock monitor is enabled (CME=1) the MCU is able to leave wait mode when loss of
oscillator/external clock is detected by a clock monitor fail. If the SCME bit is not asserted the CRG
generates a clock monitor fail reset (CMRESET). The CRG’s behavior for CMRESET is the same
compared to external reset, but another reset vector is fetched after completion of the reset sequence. If the
SCME bit is asserted the CRG generates a SCM interrupt if enabled (SCMIE=1). After generating the
interrupt the CRG enters self-clock mode and starts the clock quality checker (see Section 5.4.4, “Clock
Quality Checker”). Then the MCU continues with normal operation.If the SCM interrupt is blocked by
SCMIE = 0, the SCMIF flag will be asserted and clock quality checks will be performed but the MCU will
not wake-up from wait mode.
If any other interrupt source (e.g. RTI) triggers exit from wait mode the MCU immediately continues with
normal operation. If the PLL has been powered-down during wait mode the PLLSEL bit is cleared and the
MCU runs on OSCCLK after leaving wait mode. The software must manually set the PLLSEL bit again,
in order to switch system and core clocks to the PLLCLK.
If wait mode is entered from self-clock mode, the CRG will continue to check the clock quality until clock
check is successful. The PLL and voltage regulator (VREG) will remain enabled.
Table 5-11 summarizes the outcome of a clock loss while in wait mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
192
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-11. Outcome of Clock Loss in Wait Mode
CME
SCME
SCMIE
CRG Actions
0
X
X
Clock failure -->
No action, clock loss not detected.
1
0
X
Clock failure -->
CRG performs Clock Monitor Reset immediately
1
1
0
Clock failure -->
Scenario 1: OSCCLK recovers prior to exiting Wait Mode.
– MCU remains in Wait Mode,
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– Set SCMIF interrupt flag.
Some time later OSCCLK recovers.
– CM no longer indicates a failure,
– 4096 OSCCLK cycles later Clock Quality Check indicates clock o.k.,
– SCM deactivated,
– PLL disabled depending on PLLWAI,
– VREG remains enabled (never gets disabled in Wait Mode).
– MCU remains in Wait Mode.
Some time later either a wakeup interrupt occurs (no SCM interrupt)
– Exit Wait Mode using OSCCLK as system clock (SYSCLK),
– Continue normal operation.
or an External Reset is applied.
– Exit Wait Mode using OSCCLK as system clock,
– Start reset sequence.
Scenario 2: OSCCLK does not recover prior to exiting Wait Mode.
– MCU remains in Wait Mode,
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– Set SCMIF interrupt flag,
– Keep performing Clock Quality Checks (could continue infinitely)
while in Wait Mode.
Some time later either a wakeup interrupt occurs (no SCM interrupt)
– Exit Wait Mode in SCM using PLL clock (fSCM) as system clock,
– Continue to perform additional Clock Quality Checks until OSCCLK
is o.k. again.
or an External RESET is applied.
– Exit Wait Mode in SCM using PLL clock (fSCM) as system clock,
– Start reset sequence,
– Continue to perform additional Clock Quality Checks until OSCCLK
is o.k.again.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
193
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-11. Outcome of Clock Loss in Wait Mode (continued)
CME
SCME
SCMIE
1
1
1
CRG Actions
Clock failure -->
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– SCMIF set.
SCMIF generates Self-Clock Mode wakeup interrupt.
– Exit Wait Mode in SCM using PLL clock (fSCM) as system clock,
– Continue to perform a additional Clock Quality Checks until OSCCLK
is o.k. again.
5.4.10
Low-Power Operation in Stop Mode
All clocks are stopped in STOP mode, dependent of the setting of the PCE, PRE and PSTP bit. The
oscillator is disabled in STOP mode unless the PSTP bit is set. All counters and dividers remain frozen but
do not initialize. If the PRE or PCE bits are set, the RTI or COP continues to run in pseudo-stop mode. In
addition to disabling system and core clocks the CRG requests other functional units of the MCU (e.g.
voltage-regulator) to enter their individual power-saving modes (if available). This is the main difference
between pseudo-stop mode and wait mode.
After executing the STOP instruction the core requests the CRG to switch the MCU into stop mode. If the
PLLSEL bit remains set when entering stop mode, the CRG will switch the system and core clocks to
OSCCLK by clearing the PLLSEL bit. Then the CRG disables the PLL, disables the core clock and finally
disables the remaining system clocks. As soon as all clocks are switched off, stop mode is active.
If pseudo-stop mode (PSTP = 1) is entered from self-clock mode the CRG will continue to check the clock
quality until clock check is successful. The PLL and the voltage regulator (VREG) will remain enabled. If
full stop mode (PSTP = 0) is entered from self-clock mode an ongoing clock quality check will be stopped.
A complete timeout window check will be started when stop mode is exited again.
Wake-up from stop mode also depends on the setting of the PSTP bit.
MC9S12HZ256 Data Sheet, Rev. 2.04
194
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Core req’s
Stop Mode.
Clear
PLLSEL,
Disable PLL
Exit Stop w.
ext.RESET
no
Wait Mode left
due to external
INT
?
no
Enter
Stop Mode
PSTP=1
?
yes
CME=1
?
yes
no
Exit Stop w.
CMRESET
no
SCME=1
?
no
yes
Clock
OK
?
CM fail
?
INT
?
no
yes
no
yes
yes
Exit Stop w.
CMRESET
yes
no
SCME=1
?
yes
SCMIE=1
?
Exit
Stop Mode
Exit
Stop Mode
Generate
SCM Interrupt
(Wakeup from Stop)
no
Exit
Stop Mode
yes
Exit
Stop Mode
SCM=1
?
no
yes
Enter
SCM
Enter
SCM
Enter
SCM
Continue w.
normal OP
Figure 5-24. Stop Mode Entry/Exit Sequence
5.4.10.1
Wake-Up from Pseudo-Stop (PSTP=1)
Wake-up from pseudo-stop is the same as wake-up from wait mode. There are also three different scenarios
for the CRG to restart the MCU from pseudo-stop mode:
•
External reset
•
Clock monitor fail
•
Wake-up interrupt
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
195
Chapter 5 Clocks and Reset Generator (CRGV4)
If the MCU gets an external reset during pseudo-stop mode active, the CRG asynchronously restores all
configuration bits in the register space to its default settings and starts the reset generator. After completing
the reset sequence processing begins by fetching the normal reset vector. Pseudo-stop mode is exited and
the MCU is in run mode again.
If the clock monitor is enabled (CME = 1) the MCU is able to leave pseudo-stop mode when loss of
oscillator/external clock is detected by a clock monitor fail. If the SCME bit is not asserted the CRG
generates a clock monitor fail reset (CMRESET). The CRG’s behavior for CMRESET is the same
compared to external reset, but another reset vector is fetched after completion of the reset sequence. If the
SCME bit is asserted the CRG generates a SCM interrupt if enabled (SCMIE=1). After generating the
interrupt the CRG enters self-clock mode and starts the clock quality checker (see Section 5.4.4, “Clock
Quality Checker”). Then the MCU continues with normal operation. If the SCM interrupt is blocked by
SCMIE = 0, the SCMIF flag will be asserted but the CRG will not wake-up from pseudo-stop mode.
If any other interrupt source (e.g. RTI) triggers exit from pseudo-stop mode the MCU immediately
continues with normal operation. Because the PLL has been powered-down during stop mode the PLLSEL
bit is cleared and the MCU runs on OSCCLK after leaving stop mode. The software must set the PLLSEL
bit again, in order to switch system and core clocks to the PLLCLK.
Table 5-12 summarizes the outcome of a clock loss while in pseudo-stop mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
196
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-12. Outcome of Clock Loss in Pseudo-Stop Mode
CME
SCME
SCMIE
CRG Actions
0
X
X
Clock failure -->
No action, clock loss not detected.
1
0
X
Clock failure -->
CRG performs Clock Monitor Reset immediately
1
1
0
Clock Monitor failure -->
Scenario 1: OSCCLK recovers prior to exiting Pseudo-Stop Mode.
– MCU remains in Pseudo-Stop Mode,
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– Set SCMIF interrupt flag.
Some time later OSCCLK recovers.
– CM no longer indicates a failure,
– 4096 OSCCLK cycles later Clock Quality Check indicates clock o.k.,
– SCM deactivated,
– PLL disabled,
– VREG disabled.
– MCU remains in Pseudo-Stop Mode.
Some time later either a wakeup interrupt occurs (no SCM interrupt)
– Exit Pseudo-Stop Mode using OSCCLK as system clock (SYSCLK),
– Continue normal operation.
or an External Reset is applied.
– Exit Pseudo-Stop Mode using OSCCLK as system clock,
– Start reset sequence.
Scenario 2: OSCCLK does not recover prior to exiting Pseudo-Stop Mode.
– MCU remains in Pseudo-Stop Mode,
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– Set SCMIF interrupt flag,
– Keep performing Clock Quality Checks (could continue infinitely)
while in Pseudo-Stop Mode.
Some time later either a wakeup interrupt occurs (no SCM interrupt)
– Exit Pseudo-Stop Mode in SCM using PLL clock (fSCM) as system clock
– Continue to perform additional Clock Quality Checks until OSCCLK
is o.k. again.
or an External RESET is applied.
– Exit Pseudo-Stop Mode in SCM using PLL clock (fSCM) as system clock
– Start reset sequence,
– Continue to perform additional Clock Quality Checks until OSCCLK
is o.k.again.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
197
Chapter 5 Clocks and Reset Generator (CRGV4)
Table 5-12. Outcome of Clock Loss in Pseudo-Stop Mode (continued)
CME
SCME
SCMIE
1
1
1
CRG Actions
Clock failure -->
– VREG enabled,
– PLL enabled,
– SCM activated,
– Start Clock Quality Check,
– SCMIF set.
SCMIF generates Self-Clock Mode wakeup interrupt.
– Exit Pseudo-Stop Mode in SCM using PLL clock (fSCM) as system clock,
– Continue to perform a additional Clock Quality Checks until OSCCLK
is o.k. again.
5.4.10.2
Wake-up from Full Stop (PSTP=0)
The MCU requires an external interrupt or an external reset in order to wake-up from stop mode.
If the MCU gets an external reset during full stop mode active, the CRG asynchronously restores all
configuration bits in the register space to its default settings and will perform a maximum of 50 clock
check_windows (see Section 5.4.4, “Clock Quality Checker”). After completing the clock quality check
the CRG starts the reset generator. After completing the reset sequence processing begins by fetching the
normal reset vector. Full stop mode is exited and the MCU is in run mode again.
If the MCU is woken-up by an interrupt, the CRG will also perform a maximum of 50 clock
check_windows (see Section 5.4.4, “Clock Quality Checker”). If the clock quality check is successful, the
CRG will release all system and core clocks and will continue with normal operation. If all clock checks
within the timeout-window are failing, the CRG will switch to self-clock mode or generate a clock monitor
reset (CMRESET) depending on the setting of the SCME bit.
Because the PLL has been powered-down during stop mode the PLLSEL bit is cleared and the MCU runs
on OSCCLK after leaving stop mode. The software must manually set the PLLSEL bit again, in order to
switch system and core clocks to the PLLCLK.
NOTE
In full stop mode, the clock monitor is disabled and any loss of clock will
not be detected.
5.5
Resets
This section describes how to reset the CRG and how the CRG itself controls the reset of the MCU. It
explains all special reset requirements. Because the reset generator for the MCU is part of the CRG, this
section also describes all automatic actions that occur during or as a result of individual reset conditions.
The reset values of registers and signals are provided in Section 5.3, “Memory Map and Register
MC9S12HZ256 Data Sheet, Rev. 2.04
198
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
Definition.” All reset sources are listed in Table 5-13. Refer to the device overview chapter for related
vector addresses and priorities.
Table 5-13. Reset Summary
Reset Source
Local Enable
Power-on Reset
None
Low Voltage Reset
None
External Reset
None
Clock Monitor Reset
PLLCTL (CME=1, SCME=0)
COP Watchdog Reset
COPCTL (CR[2:0] nonzero)
The reset sequence is initiated by any of the following events:
•
Low level is detected at the RESET pin (external reset).
•
Power on is detected.
•
Low voltage is detected.
•
COP watchdog times out.
•
Clock monitor failure is detected and self-clock mode was disabled (SCME = 0).
Upon detection of any reset event, an internal circuit drives the RESET pin low for 128 SYSCLK cycles
(see Figure 5-25). Because entry into reset is asynchronous it does not require a running SYSCLK.
However, the internal reset circuit of the CRG cannot sequence out of current reset condition without a
running SYSCLK. The number of 128 SYSCLK cycles might be increased by n = 3 to 6 additional
SYSCLK cycles depending on the internal synchronization latency. After 128+n SYSCLK cycles the
RESET pin is released. The reset generator of the CRG waits for additional 64 SYSCLK cycles and then
samples the RESET pin to determine the originating source. Table 5-14 shows which vector will be
fetched.
Table 5-14. Reset Vector Selection
Sampled RESET Pin
(64 Cycles After
Release)
Clock Monitor
Reset Pending
COP Reset
Pending
1
0
0
POR / LVR / External Reset
1
1
X
Clock Monitor Reset
1
0
1
COP Reset
0
X
X
POR / LVR / External Reset
with rise of RESET pin
Vector Fetch
NOTE
External circuitry connected to the RESET pin should not include a large
capacitance that would interfere with the ability of this signal to rise to a
valid logic 1 within 64 SYSCLK cycles after the low drive is released.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
199
Chapter 5 Clocks and Reset Generator (CRGV4)
The internal reset of the MCU remains asserted while the reset generator completes the 192 SYSCLK long
reset sequence. The reset generator circuitry always makes sure the internal reset is deasserted
synchronously after completion of the 192 SYSCLK cycles. In case the RESET pin is externally driven
low for more than these 192 SYSCLK cycles (external reset), the internal reset remains asserted too.
RESET
)(
)(
CRG drives RESET pin low
RESET pin
released
)
)
SYSCLK
128+n cycles
possibly
SYSCLK
not
running
)
(
(
(
64 cycles
with n being
min 3 / max 6
cycles depending
on internal
synchronization
delay
possibly
RESET
driven low
externally
Figure 5-25. RESET Timing
5.5.1
Clock Monitor Reset
The CRG generates a clock monitor reset in case all of the following conditions are true:
•
Clock monitor is enabled (CME=1)
•
Loss of clock is detected
•
Self-clock mode is disabled (SCME=0)
The reset event asynchronously forces the configuration registers to their default settings (see Section 5.3,
“Memory Map and Register Definition”). In detail the CME and the SCME are reset to logical ‘1’ (which
doesn’t change the state of the CME bit, because it has already been set). As a consequence, the CRG
immediately enters self-clock mode and starts its internal reset sequence. In parallel the clock quality
check starts. As soon as clock quality check indicates a valid oscillator clock the CRG switches to
OSCCLK and leaves self-clock mode. Because the clock quality checker is running in parallel to the reset
generator, the CRG may leave self-clock mode while completing the internal reset sequence. When the
reset sequence is finished the CRG checks the internally latched state of the clock monitor fail circuit. If a
clock monitor fail is indicated processing begins by fetching the clock monitor reset vector.
5.5.2
Computer Operating Properly Watchdog (COP) Reset
When COP is enabled, the CRG expects sequential write of 0x0055 and 0x00AA (in this order) to the
ARMCOP register during the selected time-out period. As soon as this is done, the COP time-out period
restarts. If the program fails to do this the CRG will generate a reset. Also, if any value other than 0x0055
or 0x00AA is written, the CRG immediately generates a reset. In case windowed COP operation is enabled
MC9S12HZ256 Data Sheet, Rev. 2.04
200
Freescale Semiconductor
Chapter 5 Clocks and Reset Generator (CRGV4)
writes (0x0055 or 0x00AA) to the ARMCOP register must occur in the last 25% of the selected time-out
period. A premature write the CRG will immediately generate a reset.
As soon as the reset sequence is completed the reset generator checks the reset condition. If no clock
monitor failure is indicated and the latched state of the COP timeout is true, processing begins by fetching
the COP vector.
5.5.3
Power-On Reset, Low Voltage Reset
The on-chip voltage regulator detects when VDD to the MCU has reached a certain level and asserts
power-on reset or low voltage reset or both. As soon as a power-on reset or low voltage reset is triggered
the CRG performs a quality check on the incoming clock signal. As soon as clock quality check indicates
a valid oscillator clock signal the reset sequence starts using the oscillator clock. If after 50 check windows
the clock quality check indicated a non-valid oscillator clock the reset sequence starts using self-clock
mode.
Figure 5-26 and Figure 5-27 show the power-up sequence for cases when the RESET pin is tied to VDD
and when the RESET pin is held low.
RESET
Clock Quality Check
(no Self-Clock Mode)
)(
Internal POR
)(
128 SYSCLK
Internal RESET
64 SYSCLK
)(
Figure 5-26. RESET Pin Tied to VDD (by a Pull-Up Resistor)
RESET
Clock Quality Check
(no Self-Clock Mode)
)(
Internal POR
)(
128 SYSCLK
Internal RESET
)(
64 SYSCLK
Figure 5-27. RESET Pin Held Low Externally
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
201
Chapter 5 Clocks and Reset Generator (CRGV4)
5.6
Interrupts
The interrupts/reset vectors requested by the CRG are listed in Table 5-15. Refer to the device overview
chapter for related vector addresses and priorities.
Table 5-15. CRG Interrupt Vectors
5.6.1
Interrupt Source
CCR
Mask
Local Enable
Real-time interrupt
I bit
CRGINT (RTIE)
LOCK interrupt
I bit
CRGINT (LOCKIE)
SCM interrupt
I bit
CRGINT (SCMIE)
Real-Time Interrupt
The CRG generates a real-time interrupt when the selected interrupt time period elapses. RTI interrupts
are locally disabled by setting the RTIE bit to 0. The real-time interrupt flag (RTIF) is set to 1 when a
timeout occurs, and is cleared to 0 by writing a 1 to the RTIF bit.
The RTI continues to run during pseudo-stop mode if the PRE bit is set to 1. This feature can be used for
periodic wakeup from pseudo-stop if the RTI interrupt is enabled.
5.6.2
PLL Lock Interrupt
The CRG generates a PLL lock interrupt when the LOCK condition of the PLL has changed, either from
a locked state to an unlocked state or vice versa. Lock interrupts are locally disabled by setting the
LOCKIE bit to 0. The PLL Lock interrupt flag (LOCKIF) is set to1 when the LOCK condition has
changed, and is cleared to 0 by writing a 1 to the LOCKIF bit.
5.6.3
Self-Clock Mode Interrupt
The CRG generates a self-clock mode interrupt when the SCM condition of the system has changed, either
entered or exited self-clock mode. SCM conditions can only change if the self-clock mode enable bit
(SCME) is set to 1. SCM conditions are caused by a failing clock quality check after power-on reset (POR)
or low voltage reset (LVR) or recovery from full stop mode (PSTP = 0) or clock monitor failure. For details
on the clock quality check refer to Section 5.4.4, “Clock Quality Checker.” If the clock monitor is enabled
(CME = 1) a loss of external clock will also cause a SCM condition (SCME = 1).
SCM interrupts are locally disabled by setting the SCMIE bit to 0. The SCM interrupt flag (SCMIF) is set
to 1 when the SCM condition has changed, and is cleared to 0 by writing a 1 to the SCMIF bit.
MC9S12HZ256 Data Sheet, Rev. 2.04
202
Freescale Semiconductor
Chapter 6
Oscillator (OSCV2)
6.1
Introduction
The OSC module provides two alternative oscillator concepts:
• A low noise and low power Colpitts oscillator with amplitude limitation control (ALC)
• A robust full swing Pierce oscillator with the possibility to feed in an external square wave
6.1.1
Features
The Colpitts OSC option provides the following features:
• Amplitude limitation control (ALC) loop:
— Low power consumption and low current induced RF emission
— Sinusoidal waveform with low RF emission
— Low crystal stress (an external damping resistor is not required)
— Normal and low amplitude mode for further reduction of power and emission
• An external biasing resistor is not required
The Pierce OSC option provides the following features:
• Wider high frequency operation range
• No DC voltage applied across the crystal
• Full rail-to-rail (2.5 V nominal) swing oscillation with low EM susceptibility
• Fast start up
Common features:
• Clock monitor (CM)
• Operation from the VDDPLL 2.5 V (nominal) supply rail
6.1.2
Modes of Operation
Two modes of operation exist:
• Amplitude limitation controlled Colpitts oscillator mode suitable for power and emission critical
applications
• Full swing Pierce oscillator mode that can also be used to feed in an externally generated square
wave suitable for high frequency operation and harsh environments
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
203
Chapter 6 Oscillator (OSCV2)
6.2
External Signal Description
This section lists and describes the signals that connect off chip.
6.2.1
VDDPLL and VSSPLL — PLL Operating Voltage, PLL Ground
These pins provide the operating voltage (VDDPLL) and ground (VSSPLL) for the OSC circuitry. This
allows the supply voltage to the OSC to be independently bypassed.
6.2.2
EXTAL and XTAL — Clock/Crystal Source Pins
These pins provide the interface for either a crystal or a CMOS compatible clock to control the internal
clock generator circuitry. EXTAL is the external clock input or the input to the crystal oscillator amplifier.
XTAL is the output of the crystal oscillator amplifier. All the MCU internal system clocks are derived from
the EXTAL input frequency. In full stop mode (PSTP = 0) the EXTAL pin is pulled down by an internal
resistor of typical 200 kΩ.
NOTE
Freescale Semiconductor recommends an evaluation of the application
board and chosen resonator or crystal by the resonator or crystal supplier.
The Crystal circuit is changed from standard.
The Colpitts circuit is not suited for overtone resonators and crystals.
EXTAL
CDC*
MCU
C1
Crystal or Ceramic
Resonator
XTAL
C2
VSSPLL
* Due to the nature of a translated ground Colpitts oscillator
a DC voltage bias is applied to the crystal.
Please contact the crystal manufacturer for crystal DC bias
conditions and recommended capacitor value CDC.
Figure 6-1. Colpitts Oscillator Connections (XCLKS = 0)
NOTE
The Pierce circuit is not suited for overtone resonators and crystals without
a careful component selection.
MC9S12HZ256 Data Sheet, Rev. 2.04
204
Freescale Semiconductor
Chapter 6 Oscillator (OSCV2)
EXTAL
MCU
RB
C3
Crystal or Ceramic
Resonator
RS*
XTAL
C4
VSSPLL
* Rs can be zero (shorted) when used with higher frequency crystals.
Refer to manufacturer’s data.
Figure 6-2. Pierce Oscillator Connections (XCLKS = 1)
EXTAL
CMOS-Compatible
External Oscillator
(VDDPLL Level)
MCU
XTAL
Not Connected
Figure 6-3. External Clock Connections (XCLKS = 1)
6.2.3
XCLKS — Colpitts/Pierce Oscillator Selection Signal
The XCLKS is an input signal which controls whether a crystal in combination with the internal Colpitts
(low power) oscillator is used or whether the Pierce oscillator/external clock circuitry is used. The XCLKS
signal is sampled during reset with the rising edge of RESET. Table 6-1 lists the state coding of the
sampled XCLKS signal. Refer to the device overview chapter for polarity of the XCLKS pin.
Table 6-1. Clock Selection Based on XCLKS
XCLKS
Description
0
Colpitts oscillator selected
1
Pierce oscillator/external clock selected
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
205
Chapter 6 Oscillator (OSCV2)
6.3
Memory Map and Register Definition
The CRG contains the registers and associated bits for controlling and monitoring the OSC module.
6.4
Functional Description
The OSC block has two external pins, EXTAL and XTAL. The oscillator input pin, EXTAL, is intended
to be connected to either a crystal or an external clock source. The selection of Colpitts oscillator or Pierce
oscillator/external clock depends on the XCLKS signal which is sampled during reset. The XTAL pin is
an output signal that provides crystal circuit feedback.
A buffered EXTAL signal, OSCCLK, becomes the internal reference clock. To improve noise immunity,
the oscillator is powered by the VDDPLL and VSSPLL power supply pins.
The Pierce oscillator can be used for higher frequencies compared to the low power Colpitts oscillator.
6.4.1
Amplitude Limitation Control (ALC)
The Colpitts oscillator is equipped with a feedback system which does not waste current by generating
harmonics. Its configuration is “Colpitts oscillator with translated ground.” The transconductor used is
driven by a current source under the control of a peak detector which will measure the amplitude of the
AC signal appearing on EXTAL node in order to implement an amplitude limitation control (ALC) loop.
The ALC loop is in charge of reducing the quiescent current in the transconductor as a result of an increase
in the oscillation amplitude. The oscillation amplitude can be limited to two values. The normal amplitude
which is intended for non power saving modes and a small amplitude which is intended for low power
operation modes. Please refer to the CRG block description chapter for the control and assignment of the
amplitude value to operation modes.
6.4.2
Clock Monitor (CM)
The clock monitor circuit is based on an internal resistor-capacitor (RC) time delay so that it can operate
without any MCU clocks. If no OSCCLK edges are detected within this RC time delay, the clock monitor
indicates a failure which asserts self clock mode or generates a system reset depending on the state of
SCME bit. If the clock monitor is disabled or the presence of clocks is detected no failure is indicated.The
clock monitor function is enabled/disabled by the CME control bit, described in the CRG block description
chapter.
6.5
Interrupts
OSC contains a clock monitor, which can trigger an interrupt or reset. The control bits and status bits for
the clock monitor are described in the CRG block description chapter.
MC9S12HZ256 Data Sheet, Rev. 2.04
206
Freescale Semiconductor
Chapter 7
Analog-to-Digital Converter (ATD10B16CV4)
7.1
Introduction
The ATD10B16C is a 16-channel, 10-bit, multiplexed input successive approximation analog-to-digital
converter. Refer to the Electrical Specifications chapter for ATD accuracy.
7.1.1
•
•
•
•
•
•
•
•
•
•
•
•
•
•
7.1.2
Features
8-/10-bit resolution
7 µs, 10-bit single conversion time
Sample buffer amplifier
Programmable sample time
Left/right justified, signed/unsigned result data
External trigger control
Conversion completion interrupt generation
Analog input multiplexer for 16 analog input channels
Analog/digital input pin multiplexing
1 to 16 conversion sequence lengths
Continuous conversion mode
Multiple channel scans
Configurable external trigger functionality on any AD channel or any of four additional trigger
inputs. The four additional trigger inputs can be chip external or internal. Refer to device
specification for availability and connectivity
Configurable location for channel wrap around (when converting multiple channels in a sequence)
Modes of Operation
There is software programmable selection between performing single or continuous conversion on a
single channel or multiple channels.
7.1.3
Block Diagram
Refer to Figure 7-1 for a block diagram of the ATD0B16C block.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
207
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Bus Clock
ATD clock
Clock
Prescaler
Trigger
Mux
ETRIG0
ETRIG1
ETRIG2
ATD10B16C
Sequence Complete
Mode and
Timing Control
Interrupt
ETRIG3
(see Device Overview
chapter for availability
and connectivity)
ATDDIEN
ATDCTL1
Results
ATD 0
ATD 1
ATD 2
ATD 3
ATD 4
ATD 5
ATD 6
ATD 7
ATD 8
ATD 9
ATD 10
ATD 11
ATD 12
ATD 13
ATD 14
ATD 15
PORTAD
VDDA
VSSA
Successive
Approximation
Register (SAR)
and DAC
VRH
VRL
AN15
AN14
AN13
AN12
AN11
+
AN10
Sample & Hold
AN9
1
1
AN8
AN7
Analog
MUX
Comparator
AN6
AN5
AN4
AN3
AN2
AN1
AN0
Figure 7-1. ATD10B16C Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
208
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.2
External Signal Description
This section lists all inputs to the ATD10B16C block.
7.2.1
ANx (x = 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) — Analog Input
Channel x Pins
This pin serves as the analog input channel x. It can also be configured as general-purpose digital input
and/or external trigger for the ATD conversion.
7.2.2
ETRIG3, ETRIG2, ETRIG1, ETRIG0 — External Trigger Pins
These inputs can be configured to serve as an external trigger for the ATD conversion.
Refer to the Device Overview chapter for availability and connectivity of these inputs.
7.2.3
VRH, VRL — High Reference Voltage Pin, Low Reference Voltage Pin
VRH is the high reference voltage, VRL is the low reference voltage for ATD conversion.
7.2.4
VDDA, VSSA — Analog Circuitry Power Supply Pins
These pins are the power supplies for the analog circuitry of the ATD10B16C block.
7.3
Memory Map and Register Definition
This section provides a detailed description of all registers accessible in the ATD10B16C.
7.3.1
Module Memory Map
Table 7-1 gives an overview of all ATD10B16C registers
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
209
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
.
Table 7-1. ATD10B16C Memory Map
1
Address Offset
Use
Access
0x0000
ATD Control Register 0 (ATDCTL0)
R/W
0x0001
ATD Control Register 1 (ATDCTL1)
R/W
0x0002
ATD Control Register 2 (ATDCTL2)
R/W
0x0003
ATD Control Register 3 (ATDCTL3)
R/W
0x0004
ATD Control Register 4 (ATDCTL4)
R/W
0x0005
ATD Control Register 5 (ATDCTL5)
R/W
0x0006
ATD Status Register 0 (ATDSTAT0)
R/W
0x0007
Unimplemented
0x0008
ATD Test Register 0 (ATDTEST0)1
R
0x0009
ATD Test Register 1 (ATDTEST1)
R/W
0x000A
ATD Status Register 2 (ATDSTAT2)
R
0x000B
ATD Status Register 1 (ATDSTAT1)
R
0x000C
ATD Input Enable Register 0 (ATDDIEN0)
R/W
0x000D
ATD Input Enable Register 1 (ATDDIEN1)
R/W
0x000E
Port Data Register 0 (PORTAD0)
R
0x000F
Port Data Register 1 (PORTAD1)
R
0x0010, 0x0011
ATD Result Register 0 (ATDDR0H, ATDDR0L)
R/W
0x0012, 0x0013
ATD Result Register 1 (ATDDR1H, ATDDR1L)
R/W
0x0014, 0x0015
ATD Result Register 2 (ATDDR2H, ATDDR2L)
R/W
0x0016, 0x0017
ATD Result Register 3 (ATDDR3H, ATDDR3L)
R/W
0x0018, 0x0019
ATD Result Register 4 (ATDDR4H, ATDDR4L)
R/W
0x001A, 0x001B
ATD Result Register 5 (ATDDR5H, ATDDR5L)
R/W
0x001C, 0x001D
ATD Result Register 6 (ATDDR6H, ATDDR6L)
R/W
0x001E, 0x001F
ATD Result Register 7 (ATDDR7H, ATDDR7L)
R/W
0x0020, 0x0021
ATD Result Register 8 (ATDDR8H, ATDDR8L)
R/W
0x0022, 0x0023
ATD Result Register 9 (ATDDR9H, ATDDR9L)
R/W
0x0024, 0x0025
ATD Result Register 10 (ATDDR10H, ATDDR10L)
R/W
0x0026, 0x0027
ATD Result Register 11 (ATDDR11H, ATDDR11L)
R/W
0x0028, 0x0029
ATD Result Register 12 (ATDDR12H, ATDDR12L)
R/W
0x002A, 0x002B
ATD Result Register 13 (ATDDR13H, ATDDR13L)
R/W
0x002C, 0x002D
ATD Result Register 14 (ATDDR14H, ATDDR14L)
R/W
0x002E, 0x002F
ATD Result Register 15 (ATDDR15H, ATDDR15L)
R/W
ATDTEST0 is intended for factory test purposes only.
NOTE
Register Address = Base Address + Address Offset, where the Base Address
is defined at the MCU level and the Address Offset is defined at the module
level.
MC9S12HZ256 Data Sheet, Rev. 2.04
210
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2
Register Descriptions
This section describes in address order all the ATD10B16C registers and their individual bits.
Register
Name
0x0000
ATDCTL0
0x0001
ATDCTL1
0x0002
ATDCTL2
R
R
W
W
0x0004
ATDCTL4
W
R
R
R
W
0x0006
ATDSTAT0
W
0x0007
Unimplemented
W
R
0
0
0
0
0
0
0
AFFC
AWAI
ETRIGLE
ETRIGP
ETRIGE
ASCIE
S8C
S4C
S2C
S1C
FIFO
FRZ1
FRZ0
SRES8
SMP1
SMP0
PRS4
PRS3
PRS2
PRS1
PRS0
DJM
DSGN
SCAN
MULT
CD
CC
CB
CA
ETORF
FIFOR
CC3
CC2
CC1
CC0
ADPU
0
SCF
0
R
3
2
1
Bit 0
WRAP3
WRAP2
WRAP1
WRAP0
ETRIGCH3 ETRIGCH2 ETRIGCH1 ETRIGCH0
ASCIF
Unimplemented
W
W
0x000A
ATDSTAT2
W
0x000C
ATDDIEN0
4
R
0x0009
ATDTEST1
0x000B
ATDSTAT1
5
ETRIGSEL
R
W
0x0008
ATDTEST0
6
W
0x0003
ATDCTL3
0x0005
ATDCTL5
Bit 7
R
R
R
Unimplemented
SC
CCF15
CCF14
CCF13
CCF12
CCF11
CCF10
CCF9
CCF8
CCF7
CCF6
CCF5
CCF4
CCF3
CCF2
CCF1
CCF0
IEN15
IEN14
IEN13
IEN12
IEN11
IEN10
IEN9
IEN8
W
R
W
= Unimplemented or Reserved
u = Unaffected
Figure 7-2. ATD Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
211
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Register
Name
0x000D
ATDDIEN1
R
W
0x000E
PORTAD0
R
Bit 7
6
5
4
3
2
1
Bit 0
IEN7
IEN6
IEN5
IEN4
IEN3
IEN2
IEN1
IEN0
PTAD15
PTAD14
PTAD13
PTAD12
PTAD11
PTAD10
PTAD9
PTAD8
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
BIT 8
BIT 6
BIT 7
BIT 5
BIT 6
BIT 4
BIT 5
BIT 3
BIT 4
BIT 2
BIT 3
BIT 1
BIT 2
BIT 0
BIT 0
u
0
0
0
0
0
0
0
0
0
0
0
0
W
0x000F
PORTAD1
R
W
R BIT 9 MSB
BIT 7 MSB
0x0010–0x002F W
ATDDRxH–
ATDDRxL R
BIT 1
u
W
= Unimplemented or Reserved
u = Unaffected
Figure 7-2. ATD Register Summary (continued)
7.3.2.1
ATD Control Register 0 (ATDCTL0)
Writes to this register will abort current conversion sequence but will not start a new sequence.
R
7
6
5
4
0
0
0
0
3
2
1
0
WRAP3
WRAP2
WRAP1
WRAP0
1
1
1
1
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 7-3. ATD Control Register 0 (ATDCTL0)
Read: Anytime
Write: Anytime
Table 7-2. ATDCTL0 Field Descriptions
Field
3:0
WRAP[3:0]
Description
Wrap Around Channel Select Bits — These bits determine the channel for wrap around when doing
multi-channel conversions. The coding is summarized in Table 7-3.
MC9S12HZ256 Data Sheet, Rev. 2.04
212
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-3. Multi-Channel Wrap Around Coding
7.3.2.2
WRAP3
WRAP2
WRAP1
WRAP0
Multiple Channel Conversions
(MULT = 1) Wrap Around to AN0
after Converting
0
0
0
0
Reserved
0
0
0
1
AN1
0
0
1
0
AN2
0
0
1
1
AN3
0
1
0
0
AN4
0
1
0
1
AN5
0
1
1
0
AN6
0
1
1
1
AN7
1
0
0
0
AN8
1
0
0
1
AN9
1
0
1
0
AN10
1
0
1
1
AN11
1
1
0
0
AN12
1
1
0
1
AN13
1
1
1
0
AN14
1
1
1
1
AN15
ATD Control Register 1 (ATDCTL1)
Writes to this register will abort current conversion sequence but will not start a new sequence.
7
R
6
5
4
0
0
0
ETRIGSEL
3
2
1
0
ETRIGCH3
ETRIGCH2
ETRIGCH1
ETRIGCH0
1
1
1
1
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 7-4. ATD Control Register 1 (ATDCTL1)
Read: Anytime
Write: Anytime
Table 7-4. ATDCTL1 Field Descriptions
Field
Description
7
ETRIGSEL
External Trigger Source Select — This bit selects the external trigger source to be either one of the AD
channels or one of the ETRIG[3:0] inputs. See device specification for availability and connectivity of
ETRIG[3:0] inputs. If ETRIG[3:0] input option is not available, writing a 1 to ETRISEL only sets the bit but has
no effect, that means one of the AD channels (selected by ETRIGCH[3:0]) remains the source for external
trigger. The coding is summarized in Table 7-5.
3:0
External Trigger Channel Select — These bits select one of the AD channels or one of the ETRIG[3:0] inputs
ETRIGCH[3:0] as source for the external trigger. The coding is summarized in Table 7-5.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
213
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-5. External Trigger Channel Select Coding
1
7.3.2.3
ETRIGSEL
ETRIGCH3
ETRIGCH2
ETRIGCH1
ETRIGCH0
External Trigger Source
0
0
0
0
0
AN0
0
0
0
0
1
AN1
0
0
0
1
0
AN2
0
0
0
1
1
AN3
0
0
1
0
0
AN4
0
0
1
0
1
AN5
0
0
1
1
0
AN6
0
0
1
1
1
AN7
0
1
0
0
0
AN8
0
1
0
0
1
AN9
0
1
0
1
0
AN10
0
1
0
1
1
AN11
0
1
1
0
0
AN12
0
1
1
0
1
AN13
0
1
1
1
0
AN14
0
1
1
1
1
AN15
1
0
0
0
0
ETRIG01
1
0
0
0
1
ETRIG11
1
0
0
1
0
ETRIG21
1
0
0
1
1
ETRIG31
1
0
1
X
X
Reserved
1
1
X
X
X
Reserved
Only if ETRIG[3:0] input option is available (see device specification), else ETRISEL is ignored, that means
external trigger source remains on one of the AD channels selected by ETRIGCH[3:0]
ATD Control Register 2 (ATDCTL2)
This register controls power down, interrupt and external trigger. Writes to this register will abort current
conversion sequence but will not start a new sequence.
MC9S12HZ256 Data Sheet, Rev. 2.04
214
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7
6
5
4
3
2
1
ADPU
AFFC
AWAI
ETRIGLE
ETRIGP
ETRIGE
ASCIE
0
0
0
0
0
0
0
R
0
ASCIF
W
Reset
0
= Unimplemented or Reserved
Figure 7-5. ATD Control Register 2 (ATDCTL2)
Read: Anytime
Write: Anytime
Table 7-6. ATDCTL2 Field Descriptions
Field
Description
7
ADPU
ATD Power Down — This bit provides on/off control over the ATD10B16C block allowing reduced MCU power
consumption. Because analog electronic is turned off when powered down, the ATD requires a recovery time
period after ADPU bit is enabled.
0 Power down ATD
1 Normal ATD functionality
6
AFFC
ATD Fast Flag Clear All
0 ATD flag clearing operates normally (read the status register ATDSTAT1 before reading the result register
to clear the associate CCF flag).
1 Changes all ATD conversion complete flags to a fast clear sequence. Any access to a result register will
cause the associate CCF flag to clear automatically.
5
AWAI
ATD Power Down in Wait Mode — When entering Wait Mode this bit provides on/off control over the
ATD10B16C block allowing reduced MCU power. Because analog electronic is turned off when powered down,
the ATD requires a recovery time period after exit from Wait mode.
0 ATD continues to run in Wait mode
1 Halt conversion and power down ATD during Wait mode
After exiting Wait mode with an interrupt conversion will resume. But due to the recovery time the result of
this conversion should be ignored.
4
ETRIGLE
External Trigger Level/Edge Control — This bit controls the sensitivity of the external trigger signal. See
Table 7-7 for details.
3
ETRIGP
External Trigger Polarity — This bit controls the polarity of the external trigger signal. See Table 7-7 for
details.
2
ETRIGE
External Trigger Mode Enable — This bit enables the external trigger on one of the AD channels or one of
the ETRIG[3:0] inputs as described in Table 7-5. If external trigger source is one of the AD channels, the digital
input buffer of this channel is enabled. The external trigger allows to synchronize the start of conversion with
external events.
0 Disable external trigger
1 Enable external trigger
1
ASCIE
ATD Sequence Complete Interrupt Enable
0 ATD Sequence Complete interrupt requests are disabled.
1 ATD Interrupt will be requested whenever ASCIF = 1 is set.
0
ASCIF
ATD Sequence Complete Interrupt Flag — If ASCIE = 1 the ASCIF flag equals the SCF flag (see
Section 7.3.2.7, “ATD Status Register 0 (ATDSTAT0)”), else ASCIF reads zero. Writes have no effect.
0 No ATD interrupt occurred
1 ATD sequence complete interrupt pending
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
215
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-7. External Trigger Configurations
ETRIGLE
ETRIGP
External Trigger Sensitivity
0
0
Falling Edge
0
1
Ring Edge
1
0
Low Level
1
1
High Level
MC9S12HZ256 Data Sheet, Rev. 2.04
216
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.4
ATD Control Register 3 (ATDCTL3)
This register controls the conversion sequence length, FIFO for results registers and behavior in Freeze
Mode. Writes to this register will abort current conversion sequence but will not start a new sequence.
7
R
6
5
4
3
2
1
0
S8C
S4C
S2C
S1C
FIFO
FRZ1
FRZ0
0
1
0
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 7-6. ATD Control Register 3 (ATDCTL3)
Read: Anytime
Write: Anytime
Table 7-8. ATDCTL3 Field Descriptions
Field
Description
6
S8C
Conversion Sequence Length — This bit controls the number of conversions per sequence. Table 7-9 shows
all combinations. At reset, S4C is set to 1 (sequence length is 4). This is to maintain software continuity to HC12
Family.
5
S4C
Conversion Sequence Length — This bit controls the number of conversions per sequence. Table 7-9 shows
all combinations. At reset, S4C is set to 1 (sequence length is 4). This is to maintain software continuity to HC12
Family.
4
S2C
Conversion Sequence Length — This bit controls the number of conversions per sequence. Table 7-9 shows
all combinations. At reset, S4C is set to 1 (sequence length is 4). This is to maintain software continuity to HC12
Family.
3
S1C
Conversion Sequence Length — This bit controls the number of conversions per sequence. Table 7-9 shows
all combinations. At reset, S4C is set to 1 (sequence length is 4). This is to maintain software continuity to HC12
Family.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
217
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-8. ATDCTL3 Field Descriptions (continued)
Field
Description
2
FIFO
Result Register FIFO Mode —If this bit is zero (non-FIFO mode), the A/D conversion results map into the
result registers based on the conversion sequence; the result of the first conversion appears in the first result
register, the second result in the second result register, and so on.
If this bit is one (FIFO mode) the conversion counter is not reset at the beginning or ending of a conversion
sequence; sequential conversion results are placed in consecutive result registers. In a continuously scanning
conversion sequence, the result register counter will wrap around when it reaches the end of the result register
file. The conversion counter value (CC3-0 in ATDSTAT0) can be used to determine where in the result register
file, the current conversion result will be placed.
Aborting a conversion or starting a new conversion by write to an ATDCTL register (ATDCTL5-0) clears the
conversion counter even if FIFO=1. So the first result of a new conversion sequence, started by writing to
ATDCTL5, will always be place in the first result register (ATDDDR0). Intended usage of FIFO mode is
continuos conversion (SCAN=1) or triggered conversion (ETRIG=1).
Finally, which result registers hold valid data can be tracked using the conversion complete flags. Fast flag clear
mode may or may not be useful in a particular application to track valid data.
0 Conversion results are placed in the corresponding result register up to the selected sequence length.
1 Conversion results are placed in consecutive result registers (wrap around at end).
1:0
FRZ[1:0]
Background Debug Freeze Enable — When debugging an application, it is useful in many cases to have the
ATD pause when a breakpoint (Freeze Mode) is encountered. These 2 bits determine how the ATD will respond
to a breakpoint as shown in Table 7-10. Leakage onto the storage node and comparator reference capacitors
may compromise the accuracy of an immediately frozen conversion depending on the length of the freeze
period.
Table 7-9. Conversion Sequence Length Coding
S8C
S4C
S2C
S1C
Number of Conversions
per Sequence
0
0
0
0
16
0
0
0
1
1
0
0
1
0
2
0
0
1
1
3
0
1
0
0
4
0
1
0
1
5
0
1
1
0
6
0
1
1
1
7
1
0
0
0
8
1
0
0
1
9
1
0
1
0
10
1
0
1
1
11
1
1
0
0
12
1
1
0
1
13
1
1
1
0
14
1
1
1
1
15
MC9S12HZ256 Data Sheet, Rev. 2.04
218
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-10. ATD Behavior in Freeze Mode (Breakpoint)
FRZ1
FRZ0
Behavior in Freeze Mode
0
0
Continue conversion
0
1
Reserved
1
0
Finish current conversion, then freeze
1
1
Freeze Immediately
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
219
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.5
ATD Control Register 4 (ATDCTL4)
This register selects the conversion clock frequency, the length of the second phase of the sample time and
the resolution of the A/D conversion (i.e., 8-bits or 10-bits). Writes to this register will abort current
conversion sequence but will not start a new sequence.
7
6
5
4
3
2
1
0
SRES8
SMP1
SMP0
PRS4
PRS3
PRS2
PRS1
PRS0
0
0
0
0
0
1
0
1
R
W
Reset
Figure 7-7. ATD Control Register 4 (ATDCTL4)
Read: Anytime
Write: Anytime
Table 7-11. ATDCTL4 Field Descriptions
Field
Description
7
SRES8
A/D Resolution Select — This bit selects the resolution of A/D conversion results as either 8 or 10 bits. The
A/D converter has an accuracy of 10 bits. However, if low resolution is required, the conversion can be speeded
up by selecting 8-bit resolution.
0 10 bit resolution
1 8 bit resolution
6:5
SMP[1:0]
Sample Time Select —These two bits select the length of the second phase of the sample time in units of ATD
conversion clock cycles. Note that the ATD conversion clock period is itself a function of the prescaler value
(bits PRS4-0). The sample time consists of two phases. The first phase is two ATD conversion clock cycles
long and transfers the sample quickly (via the buffer amplifier) onto the A/D machine’s storage node. The
second phase attaches the external analog signal directly to the storage node for final charging and high
accuracy. Table 7-12 lists the lengths available for the second sample phase.
4:0
PRS[4:0]
ATD Clock Prescaler — These 5 bits are the binary value prescaler value PRS. The ATD conversion clock
frequency is calculated as follows:
[ BusClock ]
ATDclock = -------------------------------- × 0.5
[ PRS + 1 ]
Note: The maximum ATD conversion clock frequency is half the bus clock. The default (after reset) prescaler
value is 5 which results in a default ATD conversion clock frequency that is bus clock divided by 12.
Table 7-13 illustrates the divide-by operation and the appropriate range of the bus clock.
Table 7-12. Sample Time Select
SMP1
SMP0
Length of 2nd Phase of Sample Time
0
0
2 A/D conversion clock periods
0
1
4 A/D conversion clock periods
1
0
8 A/D conversion clock periods
1
1
16 A/D conversion clock periods
MC9S12HZ256 Data Sheet, Rev. 2.04
220
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-13. Clock Prescaler Values
Prescale Value
Total Divisor
Value
Max. Bus Clock1
Min. Bus Clock2
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
Divide by 2
Divide by 4
Divide by 6
Divide by 8
Divide by 10
Divide by 12
Divide by 14
Divide by 16
Divide by 18
Divide by 20
Divide by 22
Divide by 24
Divide by 26
Divide by 28
Divide by 30
Divide by 32
Divide by 34
Divide by 36
Divide by 38
Divide by 40
Divide by 42
Divide by 44
Divide by 46
Divide by 48
Divide by 50
Divide by 52
Divide by 54
Divide by 56
Divide by 58
Divide by 60
Divide by 62
Divide by 64
4 MHz
8 MHz
12 MHz
16 MHz
20 MHz
24 MHz
28 MHz
32 MHz
36 MHz
40 MHz
44 MHz
48 MHz
52 MHz
56 MHz
60 MHz
64 MHz
68 MHz
72 MHz
76 MHz
80 MHz
84 MHz
88 MHz
92 MHz
96 MHz
100 MHz
104 MHz
108 MHz
112 MHz
116 MHz
120 MHz
124 MHz
128 MHz
1 MHz
2 MHz
3 MHz
4 MHz
5 MHz
6 MHz
7 MHz
8 MHz
9 MHz
10 MHz
11 MHz
12 MHz
13 MHz
14 MHz
15 MHz
16 MHz
17 MHz
18 MHz
19 MHz
20 MHz
21 MHz
22 MHz
23 MHz
24 MHz
25 MHz
26 MHz
27 MHz
28 MHz
29 MHz
30 MHz
31 MHz
32 MHz
1
Maximum ATD conversion clock frequency is 2 MHz. The maximum allowed bus clock frequency is
shown in this column.
2
Minimum ATD conversion clock frequency is 500 kHz. The minimum allowed bus clock frequency is
shown in this column.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
221
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.6
ATD Control Register 5 (ATDCTL5)
This register selects the type of conversion sequence and the analog input channels sampled. Writes to this
register will abort current conversion sequence and start a new conversion sequence. If external trigger is
enabled (ETRIGE = 1) an initial write to ATDCTL5 is required to allow starting of a conversion sequence
which will then occur on each trigger event. Start of conversion means the beginning of the sampling
phase.
7
6
5
4
3
2
1
0
DJM
DSGN
SCAN
MULT
CD
CC
CB
CA
0
0
0
0
0
0
0
0
R
W
Reset
Figure 7-8. ATD Control Register 5 (ATDCTL5)
Read: Anytime
Write: Anytime
Table 7-14. ATDCTL5 Field Descriptions
Field
Description
7
DJM
Result Register Data Justification — This bit controls justification of conversion data in the result registers.
See Section 7.3.2.16, “ATD Conversion Result Registers (ATDDRx)” for details.
0 Left justified data in the result registers.
1 Right justified data in the result registers.
6
DSGN
Result Register Data Signed or Unsigned Representation — This bit selects between signed and unsigned
conversion data representation in the result registers. Signed data is represented as 2’s complement. Signed
data is not available in right justification. See <st-bold>7.3.2.16 ATD Conversion Result Registers (ATDDRx)
for details.
0 Unsigned data representation in the result registers.
1 Signed data representation in the result registers.
Table 7-15 summarizes the result data formats available and how they are set up using the control bits.
Table 7-16 illustrates the difference between the signed and unsigned, left justified output codes for an input
signal range between 0 and 5.12 Volts.
5
SCAN
Continuous Conversion Sequence Mode — This bit selects whether conversion sequences are performed
continuously or only once. If external trigger is enabled (ETRIGE=1) setting this bit has no effect, that means
each trigger event starts a single conversion sequence.
0 Single conversion sequence
1 Continuous conversion sequences (scan mode)
4
MULT
Multi-Channel Sample Mode — When MULT is 0, the ATD sequence controller samples only from the
specified analog input channel for an entire conversion sequence. The analog channel is selected by channel
selection code (control bits CD/CC/CB/CA located in ATDCTL5). When MULT is 1, the ATD sequence controller
samples across channels. The number of channels sampled is determined by the sequence length value (S8C,
S4C, S2C, S1C). The first analog channel examined is determined by channel selection code (CC, CB, CA
control bits); subsequent channels sampled in the sequence are determined by incrementing the channel
selection code or wrapping around to AN0 (channel 0.
0 Sample only one channel
1 Sample across several channels
MC9S12HZ256 Data Sheet, Rev. 2.04
222
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-14. ATDCTL5 Field Descriptions (continued)
Field
Description
3:0
C[D:A}
Analog Input Channel Select Code — These bits select the analog input channel(s) whose signals are
sampled and converted to digital codes. Table 7-17 lists the coding used to select the various analog input
channels.
In the case of single channel conversions (MULT = 0), this selection code specified the channel to be examined.
In the case of multiple channel conversions (MULT = 1), this selection code represents the first channel to be
examined in the conversion sequence. Subsequent channels are determined by incrementing the channel
selection code or wrapping around to AN0 (after converting the channel defined by the Wrap Around Channel
Select Bits WRAP[3:0] in ATDCTL0). In case starting with a channel number higher than the one defined by
WRAP[3:0] the first wrap around will be AN15 to AN0.
Table 7-15. Available Result Data Formats.
SRES8
DJM
DSGN
Result Data Formats
Description and Bus Bit Mapping
1
0
0
8-bit / left justified / unsigned — bits 15:8
1
0
1
8-bit / left justified / signed — bits 15:8
1
1
X
8-bit / right justified / unsigned — bits 7:0
0
0
0
10-bit / left justified / unsigned — bits 15:6
0
0
1
10-bit / left justified / signed -— bits 15:6
0
1
X
10-bit / right justified / unsigned — bits 9:0
Table 7-16. Left Justified, Signed and Unsigned ATD Output Codes.
Input Signal
VRL = 0 Volts
VRH = 5.12 Volts
Signed
8-Bit Codes
Unsigned
8-Bit Codes
Signed
10-Bit Codes
Unsigned
10-Bit Codes
5.120 Volts
7F
FF
7FC0
FFC0
5.100
7F
FF
7F00
FF00
5.080
7E
FE
7E00
FE00
2.580
01
81
0100
8100
2.560
00
80
0000
8000
2.540
FF
7F
FF00
7F00
0.020
81
01
8100
0100
0.000
80
00
8000
0000
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
223
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-17. Analog Input Channel Select Coding
CD
CC
CB
CA
Analog Input
Channel
0
0
0
0
AN0
0
0
0
1
AN1
0
0
1
0
AN2
0
0
1
1
AN3
0
1
0
0
AN4
0
1
0
1
AN5
0
1
1
0
AN6
0
1
1
1
AN7
1
0
0
0
AN8
1
0
0
1
AN9
1
0
1
0
AN10
1
0
1
1
AN11
1
1
0
0
AN12
1
1
0
1
AN13
1
1
1
0
AN14
1
1
1
1
AN15
MC9S12HZ256 Data Sheet, Rev. 2.04
224
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.7
ATD Status Register 0 (ATDSTAT0)
This read-only register contains the Sequence Complete Flag, overrun flags for external trigger and FIFO
mode, and the conversion counter.
7
6
R
5
4
ETORF
FIFOR
0
0
0
SCF
3
2
1
0
CC3
CC2
CC1
CC0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 7-9. ATD Status Register 0 (ATDSTAT0)
Read: Anytime
Write: Anytime (No effect on CC[3:0])
Table 7-18. ATDSTAT0 Field Descriptions
Field
7
SCF
5
ETORF
Description
Sequence Complete Flag — This flag is set upon completion of a conversion sequence. If conversion
sequences are continuously performed (SCAN = 1), the flag is set after each one is completed. This flag is
cleared when one of the following occurs:
• Write “1” to SCF
• Write to ATDCTL5 (a new conversion sequence is started)
• If AFFC = 1 and read of a result register
0 Conversion sequence not completed
1 Conversion sequence has completed
External Trigger Overrun Flag —While in edge trigger mode (ETRIGLE = 0), if additional active edges are
detected while a conversion sequence is in process the overrun flag is set. This flag is cleared when one of the
following occurs:
• Write “1” to ETORF
• Write to ATDCTL0,1,2,3,4 (a conversion sequence is aborted)
• Write to ATDCTL5 (a new conversion sequence is started)
0 No External trigger over run error has occurred
1 External trigger over run error has occurred
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
225
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-18. ATDSTAT0 Field Descriptions (continued)
Field
Description
4
FIFOR
FIFO Over Run Flag — This bit indicates that a result register has been written to before its associated
conversion complete flag (CCF) has been cleared. This flag is most useful when using the FIFO mode because
the flag potentially indicates that result registers are out of sync with the input channels. However, it is also
practical for non-FIFO modes, and indicates that a result register has been over written before it has been read
(i.e., the old data has been lost). This flag is cleared when one of the following occurs:
• Write “1” to FIFOR
• Start a new conversion sequence (write to ATDCTL5 or external trigger)
0 No over run has occurred
1 Overrun condition exists (result register has been written while associated CCFx flag remained set)
3:0
CC[3:0}
Conversion Counter — These 4 read-only bits are the binary value of the conversion counter. The conversion
counter points to the result register that will receive the result of the current conversion. For example, CC3 = 0,
CC2 = 1, CC1 = 1, CC0 = 0 indicates that the result of the current conversion will be in ATD Result Register 6.
If in non-FIFO mode (FIFO = 0) the conversion counter is initialized to zero at the begin and end of the
conversion sequence. If in FIFO mode (FIFO = 1) the register counter is not initialized. The conversion
counters wraps around when its maximum value is reached.
Aborting a conversion or starting a new conversion by write to an ATDCTL register (ATDCTL5-0) clears the
conversion counter even if FIFO=1.
MC9S12HZ256 Data Sheet, Rev. 2.04
226
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.8
R
Reserved Register 0 (ATDTEST0)
7
6
5
4
3
2
1
0
u
u
u
u
u
u
u
u
1
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
u = Unaffected
Figure 7-10. Reserved Register 0 (ATDTEST0)
Read: Anytime, returns unpredictable values
Write: Anytime in special modes, unimplemented in normal modes
NOTE
Writing to this register when in special modes can alter functionality.
7.3.2.9
ATD Test Register 1 (ATDTEST1)
This register contains the SC bit used to enable special channel conversions.
R
7
6
5
4
3
2
1
u
u
u
u
u
u
u
0
SC
W
Reset
0
0
0
0
0
= Unimplemented or Reserved
0
0
0
u = Unaffected
Figure 7-11. Reserved Register 1 (ATDTEST1)
Read: Anytime, returns unpredictable values for bit 7 and bit 6
Write: Anytime
NOTE
Writing to this register when in special modes can alter functionality.
Table 7-19. ATDTEST1 Field Descriptions
Field
Description
0
SC
Special Channel Conversion Bit — If this bit is set, then special channel conversion can be selected using
CC, CB, and CA of ATDCTL5. Table 7-20 lists the coding.
0 Special channel conversions disabled
1 Special channel conversions enabled
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
227
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
Table 7-20. Special Channel Select Coding
SC
CD
CC
CB
CA
Analog Input Channel
1
0
0
X
X
Reserved
7.3.2.10
1
0
1
0
0
VRH
1
0
1
0
1
VRL
1
0
1
1
0
(VRH+VRL) / 2
1
0
1
1
1
Reserved
1
1
X
X
X
Reserved
ATD Status Register 2 (ATDSTAT2)
This read-only register contains the Conversion Complete Flags CCF15 to CCF8.
R
7
6
5
4
3
2
1
0
CCF15
CCF14
CCF13
CCF12
CCF11
CCF10
CCF9
CCF8
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 7-12. ATD Status Register 2 (ATDSTAT2)
Read: Anytime
Write: Anytime, no effect
Table 7-21. ATDSTAT2 Field Descriptions
Field
Description
7:0
CCF[15:8]
Conversion Complete Flag Bits — A conversion complete flag is set at the end of each conversion in a
conversion sequence. The flags are associated with the conversion position in a sequence (and also the result
register number). Therefore, CCF8 is set when the ninth conversion in a sequence is complete and the result
is available in result register ATDDR8; CCF9 is set when the tenth conversion in a sequence is complete and
the result is available in ATDDR9, and so forth. A flag CCFx (x = 15, 14, 13, 12, 11, 10, 9, 8) is cleared when
one of the following occurs:
• Write to ATDCTL5 (a new conversion sequence is started)
• If AFFC = 0 and read of ATDSTAT2 followed by read of result register ATDDRx
• If AFFC = 1 and read of result register ATDDRx
In case of a concurrent set and clear on CCFx: The clearing by method A) will overwrite the set. The clearing
by methods B) or C) will be overwritten by the set.
0 Conversion number x not completed
1 Conversion number x has completed, result ready in ATDDRx
MC9S12HZ256 Data Sheet, Rev. 2.04
228
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.11
ATD Status Register 1 (ATDSTAT1)
This read-only register contains the Conversion Complete Flags CCF7 to CCF0
R
7
6
5
4
3
2
1
0
CCF7
CCF6
CCF5
CCF4
CCF3
CCF2
CCF1
CCF0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 7-13. ATD Status Register 1 (ATDSTAT1)
Read: Anytime
Write: Anytime, no effect
Table 7-22. ATDSTAT1 Field Descriptions
Field
Description
7:0
CCF[7:0]
Conversion Complete Flag Bits — A conversion complete flag is set at the end of each conversion in a
conversion sequence. The flags are associated with the conversion position in a sequence (and also the result
register number). Therefore, CCF0 is set when the first conversion in a sequence is complete and the result is
available in result register ATDDR0; CCF1 is set when the second conversion in a sequence is complete and
the result is available in ATDDR1, and so forth. A CCF flag is cleared when one of the following occurs:
• Write to ATDCTL5 (a new conversion sequence is started)
• If AFFC = 0 and read of ATDSTAT1 followed by read of result register ATDDRx
• If AFFC = 1 and read of result register ATDDRx
In case of a concurrent set and clear on CCFx: The clearing by method A) will overwrite the set. The clearing
by methods B) or C) will be overwritten by the set.
Conversion number x not completed
Conversion number x has completed, result ready in ATDDRx
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
229
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.12
ATD Input Enable Register 0 (ATDDIEN0)
7
6
5
4
3
2
1
0
IEN15
IEN14
IEN13
IEN12
IEN11
IEN10
IEN9
IEN8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 7-14. ATD Input Enable Register 0 (ATDDIEN0)
Read: Anytime
Write: anytime
Table 7-23. ATDDIEN0 Field Descriptions
Field
Description
7:0
IEN[15:8]
ATD Digital Input Enable on Channel Bits — This bit controls the digital input buffer from the analog input
pin (ANx) to PTADx data register.
0 Disable digital input buffer to PTADx
1 Enable digital input buffer to PTADx.
Note: Setting this bit will enable the corresponding digital input buffer continuously. If this bit is set while
simultaneously using it as an analog port, there is potentially increased power consumption because the
digital input buffer maybe in the linear region.
7.3.2.13
ATD Input Enable Register 1 (ATDDIEN1)
7
6
5
4
3
2
1
0
IEN7
IEN6
IEN5
IEN4
IEN3
IEN2
IEN1
IEN0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 7-15. ATD Input Enable Register 1 (ATDDIEN1)
Read: Anytime
Write: Anytime
Table 7-24. ATDDIEN1 Field Descriptions
Field
Description
7:0
IEN[7:0]
ATD Digital Input Enable on Channel Bits — This bit controls the digital input buffer from the analog input
pin (ANx) to PTADx data register.
0 Disable digital input buffer to PTADx
1 Enable digital input buffer to PTADx.
Note: Setting this bit will enable the corresponding digital input buffer continuously. If this bit is set while
simultaneously using it as an analog port, there is potentially increased power consumption because the
digital input buffer maybe in the linear region.
MC9S12HZ256 Data Sheet, Rev. 2.04
230
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.14
Port Data Register 0 (PORTAD0)
The data port associated with the ATD is input-only. The port pins are shared with the analog A/D inputs
AN[15:8].
R
7
6
5
4
3
2
1
0
PTAD15
PTAD14
PTAD13
PTAD12
PTAD11
PTAD10
PTAD9
PTAD8
1
1
1
1
1
1
1
1
AN15
AN14
AN13
AN12
AN11
AN10
AN9
AN8
W
Reset
Pin
Function
= Unimplemented or Reserved
Figure 7-16. Port Data Register 0 (PORTAD0)
Read: Anytime
Write: Anytime, no effect
The A/D input channels may be used for general-purpose digital input.
Table 7-25. PORTAD0 Field Descriptions
Field
Description
7:0
PTAD[15:8]
A/D Channel x (ANx) Digital Input Bits— If the digital input buffer on the ANx pin is enabled (IENx = 1) or
channel x is enabled as external trigger (ETRIGE = 1, ETRIGCH[3-0] = x, ETRIGSEL = 0) read returns the
logic level on ANx pin (signal potentials not meeting VIL or VIH specifications will have an indeterminate value)).
If the digital input buffers are disabled (IENx = 0) and channel x is not enabled as external trigger, read returns
a “1”.
Reset sets all PORTAD0 bits to “1”.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
231
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.15
Port Data Register 1 (PORTAD1)
The data port associated with the ATD is input-only. The port pins are shared with the analog A/D inputs
AN7-0.
R
7
6
5
4
3
2
1
0
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
1
1
1
1
1
1
1
1
AN 7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
W
Reset
Pin
Function
= Unimplemented or Reserved
Figure 7-17. Port Data Register 1 (PORTAD1)
Read: Anytime
Write: Anytime, no effect
The A/D input channels may be used for general-purpose digital input.
Table 7-26. PORTAD1 Field Descriptions
Field
Description
7:0
PTAD[7:8]
A/D Channel x (ANx) Digital Input Bits — If the digital input buffer on the ANx pin is enabled (IENx=1) or
channel x is enabled as external trigger (ETRIGE = 1, ETRIGCH[3-0] = x, ETRIGSEL = 0) read returns the
logic level on ANx pin (signal potentials not meeting VIL or VIH specifications will have an indeterminate value)).
If the digital input buffers are disabled (IENx = 0) and channel x is not enabled as external trigger, read returns
a “1”.
Reset sets all PORTAD1 bits to “1”.
MC9S12HZ256 Data Sheet, Rev. 2.04
232
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.16
ATD Conversion Result Registers (ATDDRx)
The A/D conversion results are stored in 16 read-only result registers. The result data is formatted in the
result registers bases on two criteria. First there is left and right justification; this selection is made using
the DJM control bit in ATDCTL5. Second there is signed and unsigned data; this selection is made using
the DSGN control bit in ATDCTL5. Signed data is stored in 2’s complement format and only exists in left
justified format. Signed data selected for right justified format is ignored.
Read: Anytime
Write: Anytime in special mode, unimplemented in normal modes
7.3.2.16.1
Left Justified Result Data
7
R (10-BIT) BIT 9 MSB
R (8-BIT) BIT 7 MSB
6
5
4
3
2
1
0
BIT 8
BIT 6
BIT 7
BIT 5
BIT 6
BIT 4
BIT 5
BIT 3
BIT 4
BIT 2
BIT 3
BIT 1
BIT 2
BIT 0
0
0
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 7-18. Left Justified, ATD Conversion Result Register x, High Byte (ATDDRxH)
R (10-BIT)
R (8-BIT)
7
6
5
4
3
2
1
0
BIT 1
u
BIT 0
u
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
u = Unaffected
Figure 7-19. Left Justified, ATD Conversion Result Register x, Low Byte (ATDDRxL)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
233
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.3.2.16.2
R (10-BIT)
R (8-BIT)
Right Justified Result Data
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
BIT 9 MSB
0
BIT 8
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 7-20. Right Justified, ATD Conversion Result Register x, High Byte (ATDDRxH)
7
R (10-BIT)
BIT 7
R (8-BIT) BIT 7 MSB
6
5
4
3
2
1
0
BIT 6
BIT 6
BIT 5
BIT 5
BIT 4
BIT 4
BIT 3
BIT 3
BIT 2
BIT 2
BIT 1
BIT 1
BIT 0
BIT 0
0
0
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 7-21. Right Justified, ATD Conversion Result Register x, Low Byte (ATDDRxL)
7.4
Functional Description
The ATD10B16C is structured in an analog and a digital sub-block.
7.4.1
Analog Sub-block
The analog sub-block contains all analog electronics required to perform a single conversion. Separate
power supplies VDDA and VSSA allow to isolate noise of other MCU circuitry from the analog sub-block.
7.4.1.1
Sample and Hold Machine
The sample and hold (S/H) machine accepts analog signals from the external world and stores them as
capacitor charge on a storage node.
The sample process uses a two stage approach. During the first stage, the sample amplifier is used to
quickly charge the storage node.The second stage connects the input directly to the storage node to
complete the sample for high accuracy.
When not sampling, the sample and hold machine disables its own clocks. The analog electronics continue
drawing their quiescent current. The power down (ADPU) bit must be set to disable both the digital clocks
and the analog power consumption.
The input analog signals are unipolar and must fall within the potential range of VSSA to VDDA.
MC9S12HZ256 Data Sheet, Rev. 2.04
234
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.4.1.2
Analog Input Multiplexer
The analog input multiplexer connects one of the 16 external analog input channels to the sample and hold
machine.
7.4.1.3
Sample Buffer Amplifier
The sample amplifier is used to buffer the input analog signal so that the storage node can be quickly
charged to the sample potential.
7.4.1.4
Analog-to-Digital (A/D) Machine
The A/D machine performs analog to digital conversions. The resolution is program selectable at either 8
or 10 bits. The A/D machine uses a successive approximation architecture. It functions by comparing the
stored analog sample potential with a series of digitally generated analog potentials. By following a binary
search algorithm, the A/D machine locates the approximating potential that is nearest to the sampled
potential.
When not converting the A/D machine disables its own clocks. The analog electronics continue drawing
quiescent current. The power down (ADPU) bit must be set to disable both the digital clocks and the analog
power consumption.
Only analog input signals within the potential range of VRL to VRH (A/D reference potentials) will result
in a non-railed digital output codes.
7.4.2
Digital Sub-Block
This subsection explains some of the digital features in more detail. See register descriptions for all details.
7.4.2.1
External Trigger Input
The external trigger feature allows the user to synchronize ATD conversions to the external environment
events rather than relying on software to signal the ATD module when ATD conversions are to take place.
The external trigger signal (out of reset ATD channel 15, configurable in ATDCTL1) is programmable to
be edge or level sensitive with polarity control. Table 7-27 gives a brief description of the different
combinations of control bits and their effect on the external trigger function.
Table 7-27. External Trigger Control Bits
ETRIGLE
ETRIGP
ETRIGE
SCAN
Description
X
X
0
0
Ignores external trigger. Performs one conversion sequence and stops.
X
X
0
1
Ignores external trigger. Performs continuous conversion sequences.
0
0
1
X
Falling edge triggered. Performs one conversion sequence per trigger.
0
1
1
X
Rising edge triggered. Performs one conversion sequence per trigger.
1
0
1
X
Trigger active low. Performs continuous conversions while trigger is active.
1
1
1
X
Trigger active high. Performs continuous conversions while trigger is active.
During a conversion, if additional active edges are detected the overrun error flag ETORF is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
235
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
In either level or edge triggered modes, the first conversion begins when the trigger is received. In both
cases, the maximum latency time is one bus clock cycle plus any skew or delay introduced by the trigger
circuitry.
After ETRIGE is enabled, conversions cannot be started by a write to ATDCTL5, but rather must be
triggered externally.
If the level mode is active and the external trigger both de-asserts and re-asserts itself during a conversion
sequence, this does not constitute an overrun. Therefore, the flag is not set. If the trigger remains asserted
in level mode while a sequence is completing, another sequence will be triggered immediately.
7.4.2.2
General-Purpose Digital Input Port Operation
The input channel pins can be multiplexed between analog and digital data. As analog inputs, they are
multiplexed and sampled to supply signals to the A/D converter. As digital inputs, they supply external
input data that can be accessed through the digital port registers (PORTAD0 & PORTAD1) (input-only).
The analog/digital multiplex operation is performed in the input pads. The input pad is always connected
to the analog inputs of the ATD10B16C. The input pad signal is buffered to the digital port registers. This
buffer can be turned on or off with the ATDDIEN0 & ATDDIEN1 register. This is important so that the
buffer does not draw excess current when analog potentials are presented at its input.
7.4.3
Operation in Low Power Modes
The ATD10B16C can be configured for lower MCU power consumption in three different ways:
• Stop Mode
Stop Mode: This halts A/D conversion. Exit from Stop mode will resume A/D conversion, But due
to the recovery time the result of this conversion should be ignored.
Entering stop mode causes all clocks to halt and thus the system is placed in a minimum power
standby mode. This halts any conversion sequence in progress. During recovery from stop mode,
there must be a minimum delay for the stop recovery time tSR before initiating a new ATD
conversion sequence.
• Wait Mode
Wait Mode with AWAI = 1: This halts A/D conversion. Exit from Wait mode will resume A/D
conversion, but due to the recovery time the result of this conversion should be ignored.
Entering wait mode, the ATD conversion either continues or halts for low power depending on the
logical value of the AWAIT bit.
• Freeze Mode
Writing ADPU = 0 (Note that all ATD registers remain accessible.): This aborts any A/D
conversion in progress.
In freeze mode, the ATD10B16C will behave according to the logical values of the FRZ1 and FRZ0
bits. This is useful for debugging and emulation.
NOTE
The reset value for the ADPU bit is zero. Therefore, when this module is
reset, it is reset into the power down state.
MC9S12HZ256 Data Sheet, Rev. 2.04
236
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
7.5
Resets
At reset the ATD10B16C is in a power down state. The reset state of each individual bit is listed within
Section 7.3, “Memory Map and Register Definition,” which details the registers and their bit fields.
7.6
Interrupts
The interrupt requested by the ATD10B16C is listed in Table 7-28. Refer to MCU specification for related
vector address and priority.
Table 7-28. ATD Interrupt Vectors
Interrupt Source
Sequence Complete Interrupt
CCR Mask
Local Enable
I bit
ASCIE in ATDCTL2
See Section 7.3.2, “Register Descriptions,” for further details.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
237
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
MC9S12HZ256 Data Sheet, Rev. 2.04
238
Freescale Semiconductor
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
239
Chapter 7 Analog-to-Digital Converter (ATD10B16CV4)
MC9S12HZ256 Data Sheet, Rev. 2.04
240
Freescale Semiconductor
Chapter 8
Liquid Crystal Display (LCD32F4BV1)
8.1
Introduction
The LCD32F4B driver module has 32 frontplane drivers and 4 backplane drivers so that a maximum of
128 LCD segments are controllable. Each segment is controlled by a corresponding bit in the LCD RAM.
Four multiplex modes (1/1, 1/2, 1/3, 1/4 duty), and three bias (1/1, 1/2, 1/3) methods are available. The V0
voltage is the lowest level of the output waveform and V3 becomes the highest level. All frontplane and
backplane pins can be multiplexed with other port functions.
The LCD32F4B driver system consists of five major sub-modules:
• Timing and Control – consists of registers and control logic for frame clock generation, bias
voltage level select, frame duty select, backplane select, and frontplane select/enable to produce
the required frame frequency and voltage waveforms.
• LCD RAM – contains the data to be displayed on the LCD. Data can be read from or written to the
display RAM at any time.
• Frontplane Drivers – consists of 32 frontplane drivers.
• Backplane Drivers – consists of 4 backplane drivers.
• Voltage Generator – Based on voltage applied to VLCD, it generates the voltage levels for the
timing and control logic to produce the frontplane and backplane waveforms.
8.1.1
Features
The LCD32F4B includes these distinctive features:
• Supports five LCD operation modes
• 32 frontplane drivers
• 4 backplane drivers
— Each frontplane has an enable bit respectively
• Programmable frame clock generator
• Programmable bias voltage level selector
• On-chip generation of 4 different output voltage levels
8.1.2
Modes of Operation
The LCD32F4B module supports five operation modes with different numbers of backplanes and different
biasing levels. During pseudo stop mode and wait mode the LCD operation can be suspended under
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
241
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
software control. Depending on the state of internal bits, the LCD can operate normally or the LCD clock
generation can be turned off and the LCD32F4B module enters a power conservation state.
This is a high level description only, detailed descriptions of operating modes are contained in
Section 8.4.2, “Operation in Wait Mode”, Section 8.4.3, “Operation in Pseudo Stop Mode”, and
Section 8.4.4, “Operation in Stop Mode”.
8.1.3
Block Diagram
Figure 8-1 is a block diagram of the LCD32F4B module.
Internal Address/Data/Clocks
OSCCLK
Timing
and
Control
Logic
LCD
RAM
16 bytes
Prescaler
LCD Clock
V3
V3
V2
V2
Frontplane
Drivers
V1
Voltage
Generator
Backplane
Drivers
V0
V0
FP[31:0]
V1
VLCD
BP[3:0]
Figure 8-1. LCD32F4B Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
242
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.2
External Signal Description
The LCD32F4B module has a total of 37 external pins.
Table 8-1. Signal Properties
Name
Function
Reset State
4 backplane waveforms
BP[3:0]
Backplane waveform signals
that connect directly to the pads
High impedance
32 frontplane waveforms
FP[31:0] Frontplane waveform signals
that connect directly to the pads
High impedance
LCD voltage
8.2.1
Port
VLCD
LCD supply voltage
—
BP[3:0] — Analog Backplane Pins
This output signal vector represents the analog backplane waveforms of the LCD32F4B module and is
connected directly to the corresponding pads.
8.2.2
FP[31:0] — Analog Frontplane Pins
This output signal vector represents the analog frontplane waveforms of the LCD32F4B module and is
connected directly to the corresponding pads.
8.2.3
VLCD — LCD Supply Voltage Pin
Positive supply voltage for the LCD waveform generation.
8.3
Memory Map and Register Definition
This section provides a detailed description of all memory and registers.
8.3.1
Module Memory Map
The memory map for the LCD32F4B module is given in Table 8-2. The address listed for each register is
the address offset. The total address for each register is the sum of the base address for the LCD32F4B
module and the address offset for each register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
243
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
Table 8-2. LCD32F4B Memory Map
Address
Offset
Use
Access
0x0000
LCD Control Register 0 (LCDCR0)
Read/Write
0x0001
LCD Control Register 1 (LCDCR1)
Read/Write
0x0002
LCD Frontplane Enable Register 0 (FPENR0)
Read/Write
0x0003
LCD Frontplane Enable Register 1 (FPENR1)
Read/Write
0x0004
LCD Frontplane Enable Register 2 (FPENR2)
Read/Write
0x0005
LCD Frontplane Enable Register 3 (FPENR3)
Read/Write
0x0006
Unimplemented
0x0007
Unimplemented
0x0008
LCDRAM (Location 0)
Read/Write
0x0009
LCDRAM (Location 1)
Read/Write
0x000A
LCDRAM (Location 2)
Read/Write
0x000B
LCDRAM (Location 3)
Read/Write
0x000C
LCDRAM (Location 4)
Read/Write
0x000D
LCDRAM (Location 5)
Read/Write
0x000E
LCDRAM (Location 6)
Read/Write
0x000F
LCDRAM (Location 7)
Read/Write
0x0010
LCDRAM (Location 8)
Read/Write
0x0011
LCDRAM (Location 9)
Read/Write
0x0012
LCDRAM (Location 10)
Read/Write
0x0013
LCDRAM (Location 11)
Read/Write
0x0014
LCDRAM (Location 12)
Read/Write
0x0015
LCDRAM (Location 13)
Read/Write
0x0016
LCDRAM (Location 14)
Read/Write
0x0017
LCDRAM (Location 15)
Read/Write
MC9S12HZ256 Data Sheet, Rev. 2.04
244
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.3.2
Register Descriptions
This section consists of register descriptions. Each description includes a standard register diagram.
Details of register bit and field function follow the register diagrams, in bit order.
8.3.2.1
LCD Control Register 0 (LCDCR0)
7
6
R
5
4
3
2
1
0
LCLK2
LCLK1
LCLK0
BIAS
DUTY1
DUTY0
0
0
0
0
0
0
0
LCDEN
W
Reset
0
0
= Unimplemented or Reserved
Figure 8-2. LCD Control Register 0 (LCDCR0)
Read: anytime
Write: LCDEN anytime. To avoid segment flicker the clock prescaler bits, the bias select bit and the duty
select bits must not be changed when the LCD is enabled.
Table 8-3. LCDCR0 Field Descriptions
Field
7
LCDEN
Description
LCD32F4B Driver System Enable — The LCDEN bit starts the LCD waveform generator.
0 All frontplane and backplane pins are disabled. In addition, the LCD32F4B system is disabled
and all LCD waveform generation clocks are stopped.
1 LCD driver system is enabled. All FP[31:0] pins with FP[31:0]EN set, will output an LCD driver
waveform The BP[3:0] pins will output an LCD32F4B driver waveform based on the settings of DUTY0
and DUTY1.
5:3
LCLK[2:0]
LCD Clock Prescaler — The LCD clock prescaler bits determine the OSCCLK divider value to produce the LCD
clock frequency. For detailed description of the correlation between LCD clock prescaler bits and the divider
value please refer to Table 8-7.
2
BIAS
BIAS Voltage Level Select — This bit selects the bias voltage levels during various LCD operating modes, as
shown in Table 8-8.
1:0
DUTY[1:0]
LCD Duty Select — The DUTY1 and DUTY0 bits select the duty (multiplex mode) of the LCD32F4B driver
system, as shown in Table 8-8.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
245
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.3.2.2
R
LCD Control Register 1 (LCDCR1)
7
6
5
4
3
2
0
0
0
0
0
0
1
0
LCDSWAI
LCDRPSTP
0
0
W
Reset
0
0
0
0
0
0
Unimplemented or Reserved
Figure 8-3. LCD Control Register 1 (LCDCR1)
Read: anytime
Write: anytime
Table 8-4. LCDCR1 Field Descriptions
Field
1
LCDSWAI
Description
LCD Stop in Wait Mode — This bit controls the LCD operation while in wait mode.
0 LCD operates normally in wait mode.
1 Stop LCD32F4B driver system when in wait mode.
0
LCD Run in Pseudo Stop Mode — This bit controls the LCD operation while in pseudo stop mode.
LCDRPSTP 0 Stop LCD32F4B driver system when in pseudo stop mode.
1 LCD operates normally in pseudo stop mode.
8.3.2.3
LCD Frontplane Enable Register 0–3 (FPENR0–FPENR3)
7
6
5
4
3
2
1
0
FP7EN
FP6EN
FP5EN
FP4EN
FP3EN
FP2EN
FP1EN
FP0EN
0
0
0
0
0
0
0
0
R
W
Reset
Figure 8-4. LCD Frontplane Enable Register 0 (FPENR0)
7
6
5
4
3
2
1
0
FP15EN
FP14EN
FP13EN
FP12EN
FP11EN
FP10EN
FP9EN
FP8EN
0
0
0
0
0
0
0
0
R
W
Reset
Figure 8-5. LCD Frontplane Enable Register 1 (FPENR1)
7
6
5
4
3
2
1
0
FP23EN
FP22EN
FP21EN
FP20EN
FP19EN
FP18EN
FP17EN
FP16EN
0
0
0
0
0
0
0
0
R
W
Reset
Figure 8-6. LCD Frontplane Enable Register 2 (FPENR2)
MC9S12HZ256 Data Sheet, Rev. 2.04
246
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
7
6
5
4
3
2
1
0
FP31EN
FP30EN
FP29EN
FP28EN
FP27EN
FP26EN
FP25EN
FP24EN
0
0
0
0
0
0
0
0
R
W
Reset
Figure 8-7. LCD Frontplane Enable Register 3 (FPENR3)
These bits enable the frontplane output waveform on the corresponding frontplane pin when LCDEN = 1.
Read: anytime
Write: anytime
Table 8-5. FPENR0–FPENR3 Field Descriptions
Field
Description
31:0
Frontplane Output Enable — The FP[31:0]EN bit enables the frontplane driver outputs. If LCDEN = 0, these
FP[31:0]EN bits have no effect on the state of the I/O pins. It is recommended to set FP[31:0]EN bits before LCDEN is set.
0 Frontplane driver output disabled on FP[31:0].
1 Frontplane driver output enabled on FP[31:0].
8.3.2.4
LCD RAM (LCDRAM)
The LCD RAM consists of 16 bytes. After reset the LCD RAM contents will be indeterminate (I), as
indicated by Figure 8-8.
R
LCDRAM
W
7
6
5
4
3
2
1
0
FP1BP3
FP1BP2
FP1BP1
FP1BP0
FP0BP3
FP0BP2
FP0BP1
FP0BP0
I
I
I
I
I
I
I
I
FP3BP3
FP3BP2
FP3BP1
FP3BP0
FP2BP3
FP2BP2
FP2BP1
FP2BP0
I
I
I
I
I
I
I
I
FP5BP3
FP5BP2
FP5BP1
FP5BP0
FP4BP3
FP4BP2
FP4BP1
FP4BP0
I
I
I
I
I
I
I
I
FP7BP3
FP7BP2
FP7BP1
FP7BP0
FP6BP3
FP6BP2
FP6BP1
FP6BP0
I
I
I
I
I
I
I
I
FP9BP3
FP9BP2
FP9BP1
FP9BP0
FP8BP3
FP8BP2
FP8BP1
FP8BP0
I
I
I
I
I
I
I
I
FP11BP3
FP11BP2
FP11BP1
FP11BP0
FP10BP3
FP10BP2
FP10BP1
FP10BP0
I
I
I
I
I
I
I
I
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
I = Value is indeterminate
Figure 8-8. LCD RAM (LCDRAM)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
247
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
R
LCDRAM
W
FP13BP3
FP13BP2
FP13BP1
FP13BP0
FP12BP3
FP12BP2
FP12BP1
FP12BP0
I
I
I
I
I
I
I
I
FP15BP3
FP15BP2
FP15BP1
FP15BP0
FP14BP3
FP14BP2
FP14BP1
FP14BP0
I
I
I
I
I
I
I
I
FP17BP3
FP17BP2
FP17BP1
FP17BP0
FP16BP3
FP16BP2
FP16BP1
FP16BP0
I
I
I
I
I
I
I
I
FP19BP3
FP19BP2
FP19BP1
FP19BP0
FP18BP3
FP18BP2
FP18BP1
FP18BP0
I
I
I
I
I
I
I
I
FP21BP3
FP21BP2
FP21BP1
FP21BP0
FP20BP3
FP20BP2
FP20BP1
FP20BP0
I
I
I
I
I
I
I
I
FP23BP3
FP23BP2
FP23BP1
FP23BP0
FP22BP3
FP22BP2
FP22BP1
FP22BP0
I
I
I
I
I
I
I
I
FP25BP3
FP25BP2
FP25BP1
FP25BP0
FP24BP3
FP24BP2
FP24BP1
FP24BP0
I
I
I
I
I
I
I
I
FP27BP3
FP27BP2
FP27BP1
FP27BP0
FP26BP3
FP26BP2
FP26BP1
FP26BP0
I
I
I
I
I
I
I
I
FP29BP3
FP29BP2
FP29BP1
FP29BP0
FP28BP3
FP28BP2
FP28BP1
FP28BP0
I
I
I
I
I
I
I
I
FP31BP3
FP31BP2
FP31BP1
FP31BP0
FP30BP3
FP30BP2
FP30BP1
FP30BP0
I
I
I
I
I
I
I
I
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
R
LCDRAM
W
Reset
I = Value is indeterminate
Figure 8-8. LCD RAM (LCDRAM) (continued)
Read: anytime
Write: anytime
Table 8-6. LCD RAM Field Descriptions
Field
Description
31:0
3:0
FP[31:0]
BP[3:0]
LCD Segment ON — The FP[31:0]BP[3:0] bit displays (turns on) the LCD segment connected between FP[31:0]
and BP[3:0].
0 LCD segment OFF
1 LCD segment ON
MC9S12HZ256 Data Sheet, Rev. 2.04
248
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4
Functional Description
This section provides a complete functional description of the LCD32F4B block, detailing the operation
of the design from the end user perspective in a number of subsections.
8.4.1
8.4.1.1
LCD Driver Description
Frontplane, Backplane, and LCD System During Reset
During a reset the following conditions exist:
• The LCD32F4B system is configured in the default mode, 1/4 duty and 1/3 bias, that means all
backplanes are used.
• All frontplane enable bits, FP[31:0]EN are cleared and the ON/OFF control for the display, the
LCDEN bit is cleared, thereby forcing all frontplane and backplane driver outputs to the high
impedance state. The MCU pin state during reset is defined by the port integration module (PIM).
8.4.1.2
LCD Clock and Frame Frequency
The frequency of the oscillator clock (OSCCLK) and divider determine the LCD clock frequency. The
divider is set by the LCD clock prescaler bits, LCLK[2:0], in the LCD control register 0 (LCDCR0).
Table 8-7 shows the LCD clock and frame frequency for some multiplexed mode at OSCCLK = 16 MHz,
8 MHz, 4 MHz, 2 MHz, 1 MHz, and 0.5 MHz.
Table 8-7. LCD Clock and Frame Frequency
Oscillator
Frequency in
MHz
LCD Clock Prescaler
Divider
Frame Frequency [Hz]
LCD Clock
Frequency [Hz]
1/1 Duty
1/2 Duty
1/3 Duty
1/4 Duty
LCLK2
LCLK1
LCLK0
OSCCLK = 0.5
0
0
0
0
0
1
1024
2048
488
244
488
244
244
122
163
81
122
61
OSCCLK = 1.0
0
0
0
1
1
0
2048
4096
488
244
488
244
244
122
163
81
122
61
OSCCLK = 2.0
0
0
1
1
0
1
4096
8192
488
244
488
244
244
122
163
81
122
61
OSCCLK = 4.0
0
1
1
0
1
0
8192
16384
488
244
488
244
244
122
163
81
122
61
OSCCLK = 8.0
1
1
0
0
0
1
16384
32768
488
244
488
244
244
122
163
81
122
61
OSCCLK = 16.0
1
1
1
1
0
1
65536
131072
244
122
244
122
122
61
81
40
61
31
For other combinations of OSCCLK and divider not shown in Table 8-7, the following formula may be
used to calculate the LCD frame frequency for each multiplex mode:
OSCCLK (Hz)
LCD Frame Frequency (Hz) = ------------------------------------ ⋅ Duty
Divider
The possible divider values are shown in Table 8-7.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
249
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4.1.3
LCD RAM
For a segment on the LCD to be displayed, data must be written to the LCD RAM which is shown in
Section 8.3, “Memory Map and Register Definition”. The 128 bits in the LCD RAM correspond to the 128
segments that are driven by the frontplane and backplane drivers. Writing a 1 to a given location will result
in the corresponding display segment being driven with a differential RMS voltage necessary to turn the
segment ON when the LCDEN bit is set and the corresponding FP[31:0]EN bit is set. Writing a 0 to a given
location will result in the corresponding display segment being driven with a differential RMS voltage
necessary to turn the segment OFF. The LCD RAM is a dual port RAM that interfaces with the internal
address and data buses of the MCU. It is possible to read from LCD RAM locations for scrolling purposes.
When LCDEN = 0, the LCD RAM can be used as on-chip RAM. Writing or reading of the LCDEN bit
does not change the contents of the LCD RAM. After a reset, the LCD RAM contents will be
indeterminate.
8.4.1.4
LCD Driver System Enable and Frontplane Enable Sequencing
If LCDEN = 0 (LCD32F4B driver system disabled) and the frontplane enable bit, FP[31:0]EN, is set, the
frontplane driver waveform will not appear on the output until LCDEN is set. If LCDEN = 1 (LCD32F4B
driver system enabled), the frontplane driver waveform will appear on the output as soon as the
corresponding frontplane enable bit, FP[31:0]EN, in the registers FPENR0–FPENR3 is set.
8.4.1.5
LCD Bias and Modes of Operation
The LCD32F4B driver has five modes of operation:
• 1/1 duty (1 backplane), 1/1 bias (2 voltage levels)
• 1/2 duty (2 backplanes), 1/2 bias (3 voltage levels)
• 1/2 duty (2 backplanes), 1/3 bias (4 voltage levels)
• 1/3 duty (3 backplanes), 1/3 bias (4 voltage levels)
• 1/4 duty (4 backplanes), 1/3 bias (4 voltage levels)
The voltage levels required for the different operating modes are generated internally based on VLCD.
Changing VLCD alters the differential RMS voltage across the segments in the ON and OFF states,
thereby setting the display contrast.
The backplane waveforms are continuous and repetitive every frame. They are fixed within each operating
mode and are not affected by the data in the LCD RAM.
The frontplane waveforms generated are dependent on the state (ON or OFF) of the LCD segments as
defined in the LCD RAM. The LCD32F4B driver hardware uses the data in the LCD RAM to construct
the frontplane waveform to create a differential RMS voltage necessary to turn the segment ON or OFF.
The LCD duty is decided by the DUTY1 and DUTY0 bits in the LCD control register 0 (LCDCR0). The
number of bias voltage levels is determined by the BIAS bit in LCDCR0. Table 8-8 summarizes the
multiplex modes (duties) and the bias voltage levels that can be selected for each multiplex mode (duty).
The backplane pins have their corresponding backplane waveform output BP[3:0] in high impedance state
when in the OFF state as indicated in Table 8-8. In the OFF state the corresponding pins BP[3:0]can be
used for other functionality, for example as general purpose I/O ports.
MC9S12HZ256 Data Sheet, Rev. 2.04
250
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
Table 8-8. LCD Duty and Bias
LCDCR0 Register
Backplanes
Bias (BIAS = 0)
Bias (BIAS = 1)
Duty
DUTY1
DUTY0
BP3
BP2
BP1
BP0
1/1
1/2
1/3
1/1
1/2
1/3
1/1
0
1
OFF
OFF
OFF
BP0
YES
NA
NA
YES
NA
NA
1/2
1
0
OFF
OFF
BP1
BP0
NA
YES
NA
NA
NA
YES
1/3
1
1
OFF
BP2
BP1
BP0
NA
NA
YES
NA
NA
YES
1/4
0
0
BP3
BP2
BP1
BP0
NA
NA
YES
NA
NA
YES
8.4.2
Operation in Wait Mode
The LCD32F4B driver system operation during wait mode is controlled by the LCD stop in wait
(LCDSWAI) bit in the LCD control register 1 (LCDCR1). If LCDSWAI is reset, the LCD32F4B driver
system continues to operate during wait mode. If LCDSWAI is set, the LCD32F4B driver system is turned
off during wait mode. In this case, the LCD waveform generation clocks are stopped and the LCD32F4B
drivers pull down to VSSX those frontplane and backplane pins that were enabled before entering wait
mode. The contents of the LCD RAM and the LCD registers retain the values they had prior to entering
wait mode.
8.4.3
Operation in Pseudo Stop Mode
The LCD32F4B driver system operation during pseudo stop mode is controlled by the LCD run in pseudo
stop (LCDRPSTP) bit in the LCD control register 1 (LCDCR1). If LCDRPSTP is reset, the LCD32F4B
driver system is turned off during pseudo stop mode. In this case, the LCD waveform generation clocks
are stopped and the LCD32F4B drivers pull down to VSSX those frontplane and backplane pins that were
enabled before entering pseudo stop mode. If LCDRPSTP is set, the LCD32F4B driver system continues
to operate during pseudo stop mode. The contents of the LCD RAM and the LCD registers retain the
values they had prior to entering pseudo stop mode.
8.4.4
Operation in Stop Mode
All LCD32F4B driver system clocks are stopped, the LCD32F4B driver system pulls down to VSSX those
frontplane and backplane pins that were enabled before entering stop mode. Also, during stop mode, the
contents of the LCD RAM and the LCD registers retain the values they had prior to entering stop mode.
As a result, after exiting from stop mode, the LCD32F4B driver system clocks will run (if LCDEN = 1)
and the frontplane and backplane pins retain the functionality they had prior to entering stop mode.
8.4.5
LCD Waveform Examples
Figure 8-9 through Figure 8-13 show the timing examples of the LCD output waveforms for the available
modes of operation.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
251
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4.5.1
1/1 Duty Multiplexed with 1/1 Bias Mode
Duty = 1/1:DUTY1 = 0, DUTY0 = 1
Bias = 1/1:BIAS = 0 or BIAS = 1
V0 = V1 = VSSX, V2 = V3 = VLCD
- BP1, BP2, and BP3 are not used, a maximum of 32 segments are displayed.
1 Frame
VLCD
BP0
VSSX
VLCD
FPx (xxx0)
VSSX
VLCD
FPy (xxx1)
VSSX
+VLCD
0
BP0-FPx (OFF)
-VLCD
+VLCD
0
BP0-FPy (ON)
-VLCD
Figure 8-9. 1/1 Duty and 1/1 Bias
MC9S12HZ256 Data Sheet, Rev. 2.04
252
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4.5.2
1/2 Duty Multiplexed with 1/2 Bias Mode
Duty = 1/2:DUTY1 = 1, DUTY0 = 0
Bias = 1/2:BIAS = 0
V0 = VSSX, V1 = V2 = VLCD * 1/2, V3 = VLCD
- BP2 and BP3 are not used, a maximum of 64 segments are displayed.
1 Frame
BP0
VLCD
VLCD × 1/2
VSSX
BP1
VLCD
VLCD × 1/2
VSSX
FPx (xx10)
VLCD
VLCD × 1/2
VSSX
FPy (xx00)
VLCD
VLCD × 1/2
VSSX
FPz (xx11)
VLCD
VLCD × 1/2
VSSX
BP0-FPx (OFF)
+VLCD
+VLCD × 1/2
0
-VLCD × 1/2
-VLCD
BP1-FPx (ON)
+VLCD
+VLCD × 1/2
0
-VLCD × 1/2
-VLCD
BP0-FPy (OFF)
+VLCD
+VLCD × 1/2
0
-VLCD × 1/2
-VLCD
BP0-FPz (ON)
+VLCD
+VLCD × 1/2
0
-VLCD × 1/2
-VLCD
Figure 8-10. 1/2 Duty and 1/2 Bias
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
253
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4.5.3
1/2 Duty Multiplexed with 1/3 Bias Mode
Duty = 1/2:DUTY1 = 1, DUTY0 = 0
Bias = 1/3:BIAS = 1
V0 = VSSX, V1 = VLCD * 1/3, V2 = VLCD * 2/3, V3 = VLCD
- BP2 and BP3 are not used, a maximum of 64 segments are displayed.
1 Frame
BP0
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
BP1
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
FPx (xx10)
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
FPy (xx00)
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
FPz (xx11)
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP0-FPx (OFF)
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP1-FPx (ON)
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP0-FPy (OFF)
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP0-FPz (ON)
Figure 8-11. 1/2 Duty and 1/3 Bias
MC9S12HZ256 Data Sheet, Rev. 2.04
254
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4.5.4
1/3 Duty Multiplexed with 1/3 Bias Mode
Duty = 1/3:DUTY1 = 1, DUTY0 = 1
Bias = 1/3:BIAS = 0 or BIAS = 1
V0 = VSSX, V1 = VLCD * 1/3, V2 = VLCD * 2/3, V3 = VLCD
- BP3 is not used, a maximum of 96 segments are displayed.
1 Frame
BP0
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
BP1
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
BP2
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
FPx (x010)
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP0-FPx (OFF)
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP1-FPx (ON)
Figure 8-12. 1/3 Duty and 1/3 Bias
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
255
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.4.5.5
1/4 Duty Multiplexed with 1/3 Bias Mode
Duty = 1/4:DUTY1 = 0, DUTY0 = 0
Bias = 1/3:BIAS = 0 or BIAS = 1
V0 = VSSX, V1 = VLCD * 1/3, V2 = VLCD * 2/3, V3 = VLCD
- A maximum of 128 segments are displayed.
1 Frame
BP0
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
BP1
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
BP2
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
BP3
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
FPx (1001)
VLCD
VLCD × 2/3
VLCD × 1/3
VSSX
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP0-FPx (ON)
+VLCD
+VLCD × 2/3
+VLCD × 1/3
0
-VLCD × 1/3
-VLCD × 2/3
-VLCD
BP1-FPx (OFF)
Figure 8-13. 1/4 Duty and 1/3 Bias
MC9S12HZ256 Data Sheet, Rev. 2.04
256
Freescale Semiconductor
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
8.5
Resets
The reset values of registers and signals are described in Section 8.3, “Memory Map and Register
Definition”. The behavior of the LCD32F4B system during reset is described in Section 8.4.1, “LCD
Driver Description”.
8.6
Interrupts
This module does not generate any interrupts.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
257
Chapter 8 Liquid Crystal Display (LCD32F4BV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
258
Freescale Semiconductor
Chapter 9
Motor Controller (MC10B8CV1)
9.1
Introduction
The block MC10B8C is a PWM motor controller suitable to drive instruments in a cluster configuration
or any other loads requiring a PWM signal. The motor controller has eight PWM channels associated with
two pins each (16 pins in total).
9.1.1
Features
The MC10B8C includes the following features:
• 10/11-bit PWM counter
• 11-bit resolution with selectable PWM dithering function
• 7-bit resolution mode (fast mode): duty cycle can be changed by accessing only 1 byte/output
• Left, right, or center aligned PWM
• Output slew rate control
• This module is suited for, but not limited to, driving small stepper and air core motors used in
instrumentation applications. This module can be used for other motor control or PWM
applications that match the frequency, resolution, and output drive capabilities of the module.
9.1.2
Modes of Operation
9.1.2.1
Functional Modes
9.1.2.1.1
PWM Resolution
The motor controller can be configured to either 11- or 7-bits resolution mode by clearing or setting the
FAST bit. This bit influences all PWM channels. For details, please refer to Section 9.3.2.5, “Motor
Controller Duty Cycle Registers”.
9.1.2.1.2
Dither Function
Dither function can be selected or deselected by setting or clearing the DITH bit. This bit influences all
PWM channels. For details, please refer to Section 9.4.1.3.5, “Dither Bit (DITH)”.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
259
Chapter 9 Motor Controller (MC10B8CV1)
9.1.2.2
PWM Channel Configuration Modes
The eight PWM channels can operate in three functional modes. Those modes are, with some restrictions,
selectable for each channel independently.
9.1.2.2.1
Dual Full H-Bridge Mode
This mode is suitable to drive a stepper motor or a 360o air gauge instrument. For details, please refer to
Section 9.4.1.1.1, “Dual Full H-Bridge Mode (MCOM = 11)”. In this mode two adjacent PWM channels
are combined, and two PWM channels drive four pins.
9.1.2.2.2
Full H-Bridge Mode
This mode is suitable to drive any load requiring a PWM signal in a H-bridge configuration using two pins.
For details please refer to Section 9.4.1.1.2, “Full H-Bridge Mode (MCOM = 10)”.
9.1.2.2.3
Half H-Bridge Mode
This mode is suitable to drive a 90o instrument driven by one pin. For details, please refer to
Section 9.4.1.1.3, “Half H-Bridge Mode (MCOM = 00 or 01)”.
9.1.2.3
PWM Alignment Modes
Each PWM channel can operate independently in three different alignment modes. For details, please refer
to Section 9.4.1.3.1, “PWM Alignment Modes”.
9.1.2.4
Low-Power Modes
The behavior of the motor controller in low-power modes is programmable. For details, please refer to
Section 9.4.5, “Operation in Wait Mode” and Section 9.4.6, “Operation in Stop and Pseudo-Stop Modes”.
MC9S12HZ256 Data Sheet, Rev. 2.04
260
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
9.1.3
Block Diagram
Control Registers
FAST
DITH
Period Register
11-Bit Timer/Counter
PWM Channel Pair
PWM Channel
11
Duty Register 0
Comparator
M0C0M
M0C0P
Duty Register 1
Comparator
M0C1M
M0C1P
Duty Register 2
Comparator
M1C0M
M1C0P
Duty Register 3
Comparator
M1C1M
M1C1P
Duty Register 4
Comparator
M2C0M
M2C0P
Duty Register 5
Comparator
M2C1M
M2C1P
Duty Register 6
Comparator
M3C0M
M3C0P
Duty Register 7
Comparator
M3C1M
M3C1P
Figure 9-1. MC10B8C Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
261
Chapter 9 Motor Controller (MC10B8CV1)
9.2
External Signal Description
The motor controller is associated with 16 pins. Table 9-1 lists the relationship between the PWM channels
and signal pins as well as PWM channel pair (motor number), coils, and nodes they are supposed to drive
if all channels are set to dual full H-bridge configuration.
Table 9-1. PWM Channel and Pin Assignment
Pin Name
PWM Channel
PWM Channel Pair1
Coil
Node
M0C0M
0
0
0
Minus
1
Minus
M0C0P
M0C1M
Plus
1
M0C1P
M1C0M
Plus
2
1
0
M1C0P
M1C1M
Plus
3
1
Minus
0
Minus
1
Minus
M1C1P
M2C0M
Plus
4
2
M2C0P
M2C1M
Plus
5
M2C1P
M3C0M
Plus
6
3
0
M3C0P
M3C1M
9.2.1
Minus
Plus
7
M3C1P
1
Minus
1
Minus
Plus
A PWM Channel Pair always consists of PWM channel x and PWM channel x+1 (x = 2⋅n). The term
“PWM Channel Pair” is equivalent to the term “Motor”. E.g. Channel Pair 0 is equivalent to Motor 0
M0C0M/M0C0P/M0C1M/M0C1P — PWM Output Pins for Motor 0
High current PWM output pins that can be used for motor drive. These pins interface to the coils of
motor 0. PWM output on M0C0M results in a positive current flow through coil 0 when M0C0P is driven
to a logic high state. PWM output on M0C1M results in a positive current flow through coil 1 when
M0C1P is driven to a logic high state.
9.2.2
M1C0M/M1C0P/M1C1M/M1C1P — PWM Output Pins for Motor 1
High current PWM output pins that can be used for motor drive. These pins interface to the coils of
motor 1. PWM output on M1C0M results in a positive current flow through coil 0 when M1C0P is driven
to a logic high state. PWM output on M1C1M results in a positive current flow through coil 1 when
M1C1P is driven to a logic high state.
9.2.3
M2C0M/M2C0P/M2C1M/M2C1P — PWM Output Pins for Motor 2
High current PWM output pins that can be used for motor drive. These pins interface to the coils of
motor 2. PWM output on M2C0M results in a positive current flow through coil 0 when M2C0P is driven
MC9S12HZ256 Data Sheet, Rev. 2.04
262
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
to a logic high state. PWM output on M2C1M results in a positive current flow through coil 1 when
M2C1P is driven to a logic high state.
9.2.4
M3C0M/M3C0P/M3C1M/M3C1P — PWM Output Pins for Motor 3
High current PWM output pins that can be used for motor drive. These pins interface to the coils of
motor 3. PWM output on M3C0M results in a positive current flow through coil 0 when M3C0P is driven
to a logic high state. PWM output on M3C1M results in a positive current flow through coil 1 when
M3C1P is driven to a logic high state.
9.3
Memory Map and Register Definition
This section provides a detailed description of all registers of the 10-bit 8-channel motor controller
module.
9.3.1
Module Memory Map
Figure 9-2 shows the memory map of the 10-bit 8-channel motor controller module.
Figure 9-2. MC10B8C Memory Map
Offset
Register
Access
0x0000
Motor Controller Control Register 0 (MCCTL0)
RW
0x0001
Motor Controller Control Register 1 (MCCTL1)
RW
0x0002
Motor Controller Period Register (High Byte)
RW
0x0003
Motor Controller Period Register (Low Byte)
RW
0x0004
Reserved1
—
0x0005
Reserved
—
0x0006
Reserved
—
0x0007
Reserved
—
0x0008
Reserved
—
0x0009
Reserved
—
0x000A
Reserved
—
0x000B
Reserved
—
0x000C
Reserved
—
0x000D
Reserved
—
0x000E
Reserved
—
0x000F
Reserved
0x0010
Motor Controller Channel Control Register 0 (MCCC0)
RW
0x0011
Motor Controller Channel Control Register 1 (MCCC1)
RW
0x0012
Motor Controller Channel Control Register 2 (MCCC2)
RW
0x0013
Motor Controller Channel Control Register 3 (MCCC3)
RW
0x0014
Motor Controller Channel Control Register 4 (MCCC4)
RW
0x0015
Motor Controller Channel Control Register 5 (MCCC5)
RW
—
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
263
Chapter 9 Motor Controller (MC10B8CV1)
Figure 9-2. MC10B8C Memory Map (continued)
Offset
Register
Access
0x0016
Motor Controller Channel Control Register 6 (MCCC6)
RW
0x0017
Motor Controller Channel Control Register 7 (MCCC7)
RW
0x0018
Reserved
—
0x0019
Reserved
—
0x001A
Reserved
—
0x001B
Reserved
—
0x001C
Reserved
—
0x001D
Reserved
—
0x001E
Reserved
—
0x001F
Reserved
—
0x0020
Motor Controller Duty Cycle Register 0 (MCDC0) — High Byte
RW
0x0021
Motor Controller Duty Cycle Register 0 (MCDC0) — Low Byte
RW
0x0022
Motor Controller Duty Cycle Register 1 (MCDC1) — High Byte
RW
0x0023
Motor Controller Duty Cycle Register 1 (MCDC1) — Low Byte
RW
0x0024
Motor Controller Duty Cycle Register 2 (MCDC2) — High Byte
RW
0x0025
Motor Controller Duty Cycle Register 2 (MCDC2) — Low Byte
RW
0x0026
Motor Controller Duty Cycle Register 3 (MCDC3) — High Byte
RW
0x0027
Motor Controller Duty Cycle Register 3 (MCDC3) — Low Byte
RW
0x0028
Motor Controller Duty Cycle Register 4 (MCDC4) — High Byte
RW
0x0029
Motor Controller Duty Cycle Register 4 (MCDC4) — Low Byte
RW
0x002A
Motor Controller Duty Cycle Register 5 (MCDC5) — High Byte
RW
0x002B
Motor Controller Duty Cycle Register 5 (MCDC5) — Low Byte
RW
0x002C
Motor Controller Duty Cycle Register 6 (MCDC6) — High Byte
RW
0x002D
Motor Controller Duty Cycle Register 6 (MCDC6) — Low Byte
RW
0x002E
Motor Controller Duty Cycle Register 7 (MCDC7) — High Byte
RW
0x002F
Motor Controller Duty Cycle Register 7 (MCDC7) — Low Byte
RW
0x0030
Reserved
—
0x0031
Reserved
—
0x0032
Reserved
—
0x0033
Reserved
—
0x0034
Reserved
—
0x0035
Reserved
—
0x0036
Reserved
—
0x0037
Reserved
—
0x0038
Reserved
—
0x0039
Reserved
—
0x003A
Reserved
—
0x003B
Reserved
—
0x003C
Reserved
—
0x003D
Reserved
—
MC9S12HZ256 Data Sheet, Rev. 2.04
264
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
Figure 9-2. MC10B8C Memory Map (continued)
Offset
1
Register
Access
0x003E
Reserved
—
0x003F
Reserved
—
Write accesses to “Reserved” addresses have no effect. Read accesses to “Reserved” addresses provide
invalid data (0x0000).
9.3.2
9.3.2.1
Register Descriptions
Motor Controller Control Register 0
This register controls the operating mode of the motor controller module.
7
R
6
5
4
3
2
MCSWAI
FAST
DITH
0
0
0
0
1
0
0
MCPRE[1:0]
MCTOIF
W
Reset
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-3. Motor Controller Control Register 0 (MCCTL0)
Table 9-2. MCCTL0 Field Descriptions
Field
Description
6:5
MCPRE[1:0]
Motor Controller Prescaler Select — MCPRE1 and MCPRE0 determine the prescaler value that sets the
motor controller timer counter clock frequency (fTC). The clock source for the prescaler is the peripheral bus
clock (fBUS) as shown in Figure 9-22. Writes to MCPRE1 or MCPRE0 will not affect the timer counter clock
frequency fTC until the start of the next PWM period. Table 9-3 shows the prescaler values that result from the
possible combinations of MCPRE1 and MCPRE0
4
MCSWAI
Motor Controller Module Stop in Wait Mode
0 Entering wait mode has no effect on the motor controller module and the associated port pins maintain the
functionality they had prior to entering wait mode both during wait mode and after exiting wait mode.
1 Entering wait mode will stop the clock of the module and debias the analog circuitry. The
module will release the pins.
3
FAST
Motor Controller PWM Resolution Mode
0 PWM operates in 11-bit resolution mode, duty cycle registers of all channels are switched to word mode.
1 PWM operates in 7-bit resolution (fast) mode, duty cycle registers of all channels are switched to byte mode.
2
DITH
Motor Control/Driver Dither Feature Enable (refer to Section 9.4.1.3.5, “Dither Bit (DITH)”)
0 Dither feature is disabled.
1 Dither feature is enabled.
0
MCTOIF
Motor Controller Timer Counter Overflow Interrupt Flag — This bit is set when a motor controller timer
counter overflow occurs. The bit is cleared by writing a 1 to the bit.
0 A motor controller timer counter overflow has not occurred since the last reset or since the bit was cleared.
1 A motor controller timer counter overflow has occurred.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
265
Chapter 9 Motor Controller (MC10B8CV1)
.
Table 9-3. Prescaler Values
9.3.2.2
MCPRE[1:0]
fTC
00
fBus
01
fBus/2
10
fBus/4
11
fBus/8
Motor Controller Control Register 1
This register controls the behavior of the analog section of the motor controller as well as the interrupt
enables.
7
R
6
5
4
3
2
1
0
0
0
0
0
0
RECIRC
0
MCTOIE
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-4. Motor Controller Control Register 1 (MCCTL1)
Table 9-4. MCCTL1 Field Descriptions
Field
Description
7
RECIRC
Recirculation in (Dual) Full H-Bridge Mode (refer to Section 9.4.1.3.3, “RECIRC Bit”)— RECIRC only affects
the outputs in (dual) full H-bridge modes. In half H-bridge mode, the PWM output is always active low.
RECIRC = 1 will also invert the effect of the S bits (refer to Section 9.4.1.3.2, “Sign Bit (S)”) in (dual) full
H-bridge modes. RECIRC must be changed only while no PWM channel is operating in (dual) full H-bridge
mode; otherwise, erroneous output pattern may occur.
0 Recirculation on the high side transistors. Active state for PWM output is logic low, the static channel will
output logic high.
1 Recirculation on the low side transistors. Active state for PWM output is logic high, the static channel will
output logic low.
0
MCTOIE
Motor Controller Timer Counter Overflow Interrupt Enable
0 Interrupt disabled.
1 Interrupt enabled. An interrupt will be generated when the motor controller timer counter overflow interrupt flag
(MCTOIF) is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
266
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
9.3.2.3
Motor Controller Period Register
The period register defines PER, the number of motor controller timer counter clocks a PWM period lasts.
The motor controller timer counter is clocked with the frequency fTC. If dither mode is enabled (DITH = 1,
refer to Section 9.4.1.3.5, “Dither Bit (DITH)”), P0 is ignored and reads as a 0. In this case
PER = 2 * D[10:1].
R
15
14
13
12
11
0
0
0
0
0
10
9
8
7
6
5
4
3
2
1
0
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-5. Motor Controller Period Register (MCPER) with DITH = 0
R
15
14
13
12
11
0
0
0
0
0
10
9
8
7
6
5
4
3
2
1
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
0
0
0
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-6. Motor Controller Period Register (MCPER) with DITH = 1
For example, programming MCPER to 0x0022 (PER = 34 decimal) will result in 34 counts for each
complete PWM period. Setting MCPER to 0 will shut off all PWM channels as if MCAM[1:0] is set to 0
in all channel control registers after the next period timer counter overflow. In this case, the motor
controller releases all pins.
NOTE
Programming MCPER to 0x0001 and setting the DITH bit will be managed
as if MCPER is programmed to 0x0000. All PWM channels will be shut off
after the next period timer counter overflow.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
267
Chapter 9 Motor Controller (MC10B8CV1)
9.3.2.4
Motor Controller Channel Control Registers
Each PWM channel has one associated control register to control output delay, PWM alignment, and
output mode. The registers are named MCCC0... MCCC7. In the following, MCCC0 is described as a
reference for all eight registers.
7
6
5
4
MCOM1
MCOM0
MCAM1
MCAM0
0
0
0
0
R
3
2
0
0
1
0
CD1
CD0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 9-7. Motor Controller Control Register Channel 0–7 (MCCC0–MCCC7)
Table 9-5. MCCC0–MCCC7 Field Descriptions
Field
Description
7:6
Output Mode — MCOM1, MCOM0 control the PWM channel’s output mode. See Table 9-6.
MCOM[1:0]
5:4
MCAM[1:0]
PWM Channel Alignment Mode — MCAM1, MCAM0 control the PWM channel’s PWM alignment mode and
operation. See Table 9-7.
MCAM[1:0] and MCOM[1:0] are double buffered. The values used for the generation of the output waveform
will be copied to the working registers either at once (if all PWM channels are disabled or MCPER is set to 0)
or if a timer counter overflow occurs. Reads of the register return the most recent written value, which are not
necessarily the currently active values.
1:0
CD[1:0]
PWM Channel Delay — Each PWM channel can be individually delayed by a programmable number of PWM
timer counter clocks. The delay will be n/fTC. See Table 9-8.
Table 9-6. Output Mode
MCOM[1:0]
Output Mode
00
Half H-bridge mode, PWM on MnCxM, MnCxP is released
01
Half H-bridge mode, PWM on MnCxP, MnCxM is released
10
Full H-bridge mode
11
Dual full H-bridge mode
Table 9-7. PWM Alignment Mode
MCAM[1:0]
PWM Alignment Mode
00
Channel disabled
01
Left aligned
10
Right aligned
11
Center aligned
MC9S12HZ256 Data Sheet, Rev. 2.04
268
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
Table 9-8. Channel Delay
CD[1:0]
n [# of PWM Clocks]
00
0
01
1
10
2
11
3
NOTE
The PWM motor controller will release the pins after the next PWM timer
counter overflow without accommodating any channel delay if a single
channel has been disabled or if the period register has been cleared or all
channels have been disabled. Program one or more inactive PWM frames
(duty cycle = 0) before writing a configuration that disables a single channel
or the entire PWM motor controller.
9.3.2.5
Motor Controller Duty Cycle Registers
Each duty cycle register sets the sign and duty functionality for the respective PWM channel.
The contents of the duty cycle registers define DUTY, the number of motor controller timer counter clocks
the corresponding output is driven low (RECIRC = 0) or is driven high (RECIRC = 1). Setting all bits to 0
will give a static high output in case of RECIRC = 0; otherwise, a static low output. Values greater than
or equal to the contents of the period register will generate a static low output in case of RECIRC = 0, or
a static high output if RECIRC = 1. The layout of the duty cycle registers differ dependent upon the state
of the FAST bit in the control register 0.
15
R
14
13
12
11
S
S
S
S
S
10
9
8
7
6
5
4
3
2
1
0
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-8. Motor Controller Duty Cycle Register x (MCDCx) with FAST = 0
15
14
13
12
11
10
9
8
S
D8
D7
D6
D5
D4
D3
D2
0
0
0
0
0
0
0
0
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 9-9. Motor Controller Duty Cycle Register x (MCDCx) with FAST = 1
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
269
Chapter 9 Motor Controller (MC10B8CV1)
Table 9-9. MCDCx Field Descriptions
Field
Description
0
S
SIGN — The SIGN bit is used to define which output will drive the PWM signal in (dual) full-H-bridge modes. The
SIGN bit has no effect in half-bridge modes. See Section 9.4.1.3.2, “Sign Bit (S)”, and table Table 9-11 for
detailed information about the impact of RECIRC and SIGN bit on the PWM output.
Whenever FAST = 1, the bits D10, D9, D1, and D0 will be set to 0 if the duty cycle register is written.
For example setting MCDCx = 0x0158 with FAST = 0 gives the same output waveform as setting
MCDCx = 0x5600 with FAST = 1 (with FAST = 1, the low byte of MCDCx needs not to be written).
The state of the FAST bit has impact only during write and read operations. A change of the FAST bit (set
or clear) without writing a new value does not impact the internal interpretation of the duty cycle values.
To prevent the output from inconsistent signals, the duty cycle registers are double buffered. The motor
controller module will use working registers to generate the output signals. The working registers are
copied from the bus accessible registers at the following conditions:
• MCPER is set to 0 (all channels are disabled in this case)
• MCAM[1:0] of the respective channel is set to 0 (channel is disabled)
• A PWM timer counter overflow occurs while in half H-bridge or full H-bridge mode
• A PWM channel pair is configured to work in Dual Full H-Bridge mode and a PWM timer counter
overflow occurs after the odd1 duty cycle register of the channel pair has been written.
In this way, the output of the PWM will always be either the old PWM waveform or the new PWM
waveform, not some variation in between.
Reads of this register return the most recent value written. Reads do not necessarily return the value of the
currently active sign, duty cycle, and dither functionality due to the double buffering scheme.
1. Odd duty cycle register: MCDCx+1, x = 2⋅n
MC9S12HZ256 Data Sheet, Rev. 2.04
270
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
9.4
Functional Description
9.4.1
Modes of Operation
9.4.1.1
PWM Output Modes
The motor controller is configurable between three output modes.
• Dual full H-bridge mode can be used to control either a stepper motor or a 360° air core instrument.
In this case two PWM channels are combined.
• In full H-bridge mode, each PWM channel is updated independently.
• In half H-bridge mode, one pin of the PWM channel can generate a PWM signal to control a 90°
air core instrument (or other load requiring a PWM signal) and the other pin is unused.
The mode of operation for each PWM channel is determined by the corresponding MCOM[1:0] bits in
channel control registers. After a reset occurs, each PWM channel will be disabled, the corresponding pins
are released.
Each PWM channel consists of two pins. One output pin will generate a PWM signal. The other will
operate as logic high or low output depending on the state of the RECIRC bit (refer to Section 9.4.1.3.3,
“RECIRC Bit”), while in (dual) full H-bridge mode, or will be released, while in half H-bridge mode. The
state of the S bit in the duty cycle register determines the pin where the PWM signal is driven in full
H-bridge mode. While in half H-bridge mode, the state of the released pin is determined by other modules
associated with this pin.
Associated with each PWM channel pair n are two PWM channels, x and x + 1, where x = 2 * n and n
(0, 1, 2, 3) is the PWM channel pair number. Duty cycle register x controls the sign of the PWM signal
(which pin drives the PWM signal) and the duty cycle of the PWM signal for motor controller channel x.
The pins associated with PWM channel x are MnC0P and MnC0M. Similarly, duty cycle register x + 1
controls the sign of the PWM signal and the duty cycle of the PWM signal for channel x + 1. The pins
associated with PWM channel x + 1 are MnC1P and MnC1M. This is summarized in Table 9-10.
Table 9-10. Corresponding Registers and Pin Names for Each PWM Channel Pair
PWM
Channel
Pair Number
PWM
Channel Control
Register
Duty Cycle
Register
Channel
Number
Pin
Names
n
MCMCx
MCDCx
PWM Channel x, x = 2⋅n
MnC0M
MnC0P
MCMCx + 1
MCDCx + 1
PWM Channel x + 1, x = 2⋅n
MnC1M
MnC1P
0
MCMC0
MCDC0
PWM Channel 0
M0C0M
M0C0P
MCMC1
MCDC1
PWM Channel 1
M0C1M
M0C1P
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
271
Chapter 9 Motor Controller (MC10B8CV1)
Table 9-10. Corresponding Registers and Pin Names for Each PWM Channel Pair (continued)
PWM
Channel
Pair Number
PWM
Channel Control
Register
Duty Cycle
Register
Channel
Number
Pin
Names
1
MCMC2
MCDC2
PWM Channel 2
M1C0M
M1C0P
MCMC3
MCDC3
PWM Channel 3
M1C1M
M1C1P
2
MCMC4
MCDC4
PWM Channel 4
M2C0M
M2C0P
MCMC5
MCDC5
PWM Channel 5
M2C1M
M2C1P
3
MCMC6
MCDC6
PWM Channel 6
M3C0M
M3C0P
MCMC7
MCDC7
PWM Channel 7
M3C1M
M3C1P
9.4.1.1.1
Dual Full H-Bridge Mode (MCOM = 11)
PWM channel pairs x and x + 1 operate in dual full H-bridge mode if both channels have been enabled
(MCAM[1:0]=01, 10, or 11) and both of the corresponding output mode bits MCOM[1:0] in both PWM
channel control registers are set.
A typical configuration in dual full H-bridge mode is shown in Figure 9-10. PWM channel x drives the
PWM output signal on either MnC0P or MnC0M. If MnC0P drives the PWM signal, MnC0M will be
output either high or low depending on the RECIRC bit. If MnC0M drives the PWM signal, MnC0P will
be an output high or low. PWM channel x + 1 drives the PWM output signal on either MnC1P or MnC1M.
If MnC1P drives the PWM signal, MnC1M will be an output high or low. If MnC1M drives the PWM
signal, MnC1P will be an output high or low. This results in motor recirculation currents on the high side
drivers (RECIRC = 0) while the PWM signal is at a logic high level, or motor recirculation currents on the
low side drivers (RECIRC = 1) while the PWM signal is at a logic low level. The pin driving the PWM
signal is determined by the S (sign) bit in the corresponding duty cycle register and the state of the
RECIRC bit. The value of the PWM duty cycle is determined by the value of the D[10:0] or D[8:2] bits
respectively in the duty cycle register depending on the state of the FAST bit.
MC9S12HZ256 Data Sheet, Rev. 2.04
272
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
PWM Channel x
MnC0P
MnC0M
Motor n, Coil 0
Motor n, Coil 1
PWM Channel x + 1
MnC1P
MnC1M
Figure 9-10. Typical Dual Full H-Bridge Mode Configuration
Whenever FAST = 0 only 16-bit write accesses to the duty cycle registers are allowed, 8-bit write accesses
can lead to unpredictable duty cycles.
While fast mode is enabled (FAST = 1), 8-bit write accesses to the high byte of the duty cycle registers are
allowed, because only the high byte of the duty cycle register is used to determine the duty cycle.
The following sequence should be used to update the current magnitude and direction for coil 0 and coil
1 of the motor to achieve consistent PWM output:
1. Write to duty cycle register x
2. Write to duty cycle register x + 1.
At the next timer counter overflow, the duty cycle registers will be copied to the working duty cycle
registers. Sequential writes to the duty cycle register x will result in the previous data being overwritten.
9.4.1.1.2
Full H-Bridge Mode (MCOM = 10)
In full H-bridge mode, the PWM channels x and x + 1 operate independently. The duty cycle working
registers are updated whenever a timer counter overflow occurs.
9.4.1.1.3
Half H-Bridge Mode (MCOM = 00 or 01)
In half H-bridge mode, the PWM channels x and x + 1 operate independently. In this mode, each PWM
channel can be configured such that one pin is released and the other pin is a PWM output. Figure 9-11
shows a typical configuration in half H-bridge mode.
The two pins associated with each channel are switchable between released mode and PWM output
dependent upon the state of the MCOM[1:0] bits in the MCCCx (channel control) register. See register
description in Section 9.3.2.4, “Motor Controller Channel Control Registers”. In half H-bridge mode, the
state of the S bit has no effect.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
273
Chapter 9 Motor Controller (MC10B8CV1)
VDDM
Released
MnC0P
MnC0M
PWM Channel x
PWM Output
VDDM
VSSM
Released
PWM Channel x + 1
MnC1P
MnC1M
PWM Output
VSSM
Figure 9-11. Typical Quad Half H-Bridge Mode Configuration
9.4.1.2
Relationship Between PWM Mode and PWM Channel Enable
The pair of motor controller channels cannot be placed into dual full H-bridge mode unless both motor
controller channels have been enabled (MCAM[1:0] not equal to 00) and dual full H-bridge mode is
selected for both PWM channels (MCOM[1:0] = 11). If only one channel is set to dual full H-bridge mode,
this channel will operate in full H-bridge mode, the other as programmed.
9.4.1.3
9.4.1.3.1
Relationship Between Sign, Duty, Dither, RECIRC, Period,
and PWM Mode Functions
PWM Alignment Modes
Each PWM channel can be programmed individually to three different alignment modes. The mode is
determined by the MCAM[1:0] bits in the corresponding channel control register.
Left aligned (MCAM[1:0] = 01): The output will start active (low if RECIRC = 0 or high if RECIRC = 1)
and will turn inactive (high if RECIRC = 0 or low if RECIRC = 1) after the number of counts specified by
the corresponding duty cycle register.
MC9S12HZ256 Data Sheet, Rev. 2.04
274
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
Motor Controller
Timer Counter
Clock
Motor Controller
0
Timer Counter
99 0
15
15
99 0
PWM Output
1 Period
1 Period
100 Counts
100 Counts
DITH = 0, MCAM[1:0] = 01, MCDCx = 15, MCPER = 100, RECIRC = 0
Right aligned (MCAM[1:0] = 10): The output will start inactive (high if RECIRC = 0 and low if
RECIRC = 1) and will turn active after the number of counts specified by the difference of the contents of
period register and the corresponding duty cycle register.
Motor Controller
Timer Counter
Clock
Motor Controller
0
Timer Counter
85
99 0
85
99 0
PWM Output
1 Period
1 Period
100 Counts
100 Counts
DITH = 0, MCAM[1:0] = 10, MCDCx = 15, MCPER = 100, RECIRC = 0
Center aligned (MCAM[1:0] = 11): Even periods will be output left aligned, odd periods will be output
right aligned. PWM operation starts with the even period after the channel has been enabled. PWM
operation in center aligned mode might start with the odd period if the channel has not been disabled before
changing the alignment mode to center aligned.
Motor Controller
Timer Counter
Clock
Motor Controller
0
Timer Counter
99 0
15
85
99 0
PWM Output
1 Period
1 Period
100 Counts
100 Counts
DITH = 0, MCAM[1:0] = 11, MCDCx = 15, MCPER = 100, RECIRC = 0
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
275
Chapter 9 Motor Controller (MC10B8CV1)
9.4.1.3.2
Sign Bit (S)
Assuming RECIRC = 0 (the active state of the PWM signal is low), when the S bit for the corresponding
channel is cleared, MnC0P (if the PWM channel number is even, n = 0, 1, 2, 3, see Table 9-10) or MnC1P
(if the PWM channel number is odd, n = 0, 1, 2, 3, see Table 9-10), outputs a logic high while in (dual)
full H-bridge mode. In half H-bridge mode the state of the S bit has no effect. The PWM output signal is
generated on MnC0M (if the PWM channel number is even, n = 0, 1, 2, 3, see Table 9-10) or MnC1M (if
the PWM channel number is odd, n = 0, 1, 2, 3).
Assuming RECIRC = 0 (the active state of the PWM signal is low), when the S bit for the corresponding
channel is set, MnC0M (if the PWM channel number is even, n = 0, 1, 2, 3, see Table 9-10) or MnC1M
(if the PWM channel number is odd, n = 0, 1, 2, 3, see Table 9-10), outputs a logic high while in (dual)
full H-bridge mode. In half H-bridge mode the state of the S bit has no effect. The PWM output signal is
generated on MnC0P (if the PWM channel number is even, n = 0, 1, 2, 3, see Table 9-10) or MnC1P (if
the PWM channel number is odd, n = 0, 1, 2, 3).
Setting RECIRC = 1 will also invert the effect of the S bit such that while S = 0, MnC0P or MnC1P will
generate the PWM signal and MnC0M or MnC1M will be a static low output. While S = 1, MnC0M or
MnC1M will generate the PWM signal and MnC0P or MnC1P will be a static low output. In this case the
active state of the PWM signal will be high.
See Table 9-11 for detailed information about the impact of SIGN and RECIRC bit on the PWM output.
Table 9-11. Impact of RECIRC and SIGN Bit on the PWM Output
Output Mode
RECIRC
SIGN
MnCyM
MnCyP
1
(Dual) Full H-Bridge
0
0
PWM1
(Dual) Full H-Bridge
0
1
1
PWM
(Dual) Full H-Bridge
1
0
0
PWM2
(Dual) Full H-Bridge
1
1
PWM
1
Half H-Bridge: PWM on MnCyM
Don’t care
Don’t care
PWM
—3
Half H-Bridge: PWM on MnCyP
Don’t care
Don’t care
—
PWM
1
PWM: The PWM signal is low active. e.g., the waveform starts with 0 in left aligned mode. Output M generates the PWM signal.
Output P is static high.
2 PWM: The PWM signal is high active. e.g., the waveform starts with 1 in left aligned mode. output P generates the PWM signal.
Output M is static low.
3 The state of the output transistors is not controlled by the motor controller.
9.4.1.3.3
RECIRC Bit
The RECIRC bit controls the flow of the recirculation current of the load. Setting RECIRC = 0 will cause
recirculation current to flow through the high side transistors, and RECIRC = 1 will cause the recirculation
current to flow through the low side transistors. The RECIRC bit is only active in (dual) full H-bridge
modes.
Effectively, RECIRC = 0 will cause a static high output on the output terminal not driven by the PWM,
RECIRC = 1 will cause a static low output on the output terminals not driven by the PWM. To achieve the
same current direction, the S bit behavior is inverted if RECIRC = 1. Figure 9-12, Figure 9-13,
Figure 9-14, and Figure 9-15 illustrate the effect of the RECIRC bit in (dual) full H-bridge modes.
MC9S12HZ256 Data Sheet, Rev. 2.04
276
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
RECIRC bit must be changed only while no PWM channel is operated in (dual) full H-bridge mode.
VDDM
Static 0
PWM 1
MnC0P
MnC0M
Static 0
PWM 1
VSSM
Figure 9-12. PWM Active Phase, RECIRC = 0, S = 0
VDDM
Static 0
PWM 0
MnC0P
MnC0M
Static 0
PWM 0
VSSM
Figure 9-13. PWM Passive Phase, RECIRC = 0, S = 0
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
277
Chapter 9 Motor Controller (MC10B8CV1)
VDDM
Static 1
PWM 0
MnC0P
MnC0M
Static 1
PWM 0
VSSM
Figure 9-14. PWM Active Phase, RECIRC = 1, S = 0
VDDM
Static 1
PWM 1
MnC0P
MnC0M
PWM 1
Static 1
VSSM
Figure 9-15. PWM Passive Phase, RECIRC = 1, S = 0
MC9S12HZ256 Data Sheet, Rev. 2.04
278
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
9.4.1.3.4
Relationship Between RECIRC Bit, S Bit, MCOM Bits, PWM State, and Output
Transistors
Please refer to Figure 9-16 for the output transistor assignment.
VDDM
T3
T1
MnCyP
MnCyM
T2
T4
VSSM
Figure 9-16. Output Transistor Assignment
Table 9-12 illustrates the state of the output transistors in different states of the PWM motor controller
module. ‘—’ means that the state of the output transistor is not controlled by the motor controller.
Table 9-12. State of Output Transistors in Various Modes
Mode
MCOM[1:0]
PWM Duty
RECIRC
S
T1
T2
T3
T4
Off
Don’t care
—
Don’t care
Don’t care
—
—
—
—
Half H-Bridge
00
Active
Don’t care
Don’t care
—
—
OFF
ON
Half H-Bridge
00
Passive
Don’t care
Don’t care
—
—
ON
OFF
Half H-Bridge
01
Active
Don’t care
Don’t care
OFF
ON
—
—
Half H-Bridge
01
Passive
Don’t care
Don’t care
ON
OFF
—
—
(Dual) Full
10 or 11
Active
0
0
ON
OFF
OFF
ON
(Dual) Full
10 or 11
Passive
0
0
ON
OFF
ON
OFF
(Dual) Full
10 or 11
Active
0
1
OFF
ON
ON
OFF
(Dual) Full
10 or 11
Passive
0
1
ON
OFF
ON
OFF
(Dual) Full
10 or 11
Active
1
0
ON
OFF
OFF
ON
(Dual) Full
10 or 11
Passive
1
0
OFF
ON
OFF
ON
(Dual) Full
10 or 11
Active
1
1
OFF
ON
ON
OFF
(Dual) Full
10 or 11
Passive
1
1
OFF
ON
OFF
ON
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
279
Chapter 9 Motor Controller (MC10B8CV1)
9.4.1.3.5
Dither Bit (DITH)
The purpose of the dither mode is to increase the minimum length of output pulses without decreasing the
PWM resolution, in order to limit the pulse distortion introduced by the slew rate control of the outputs. If
dither mode is selected the output pattern will repeat after two timer counter overflows. For the same
output frequency, the shortest output pulse will have twice the length while dither feature is selected. To
achieve the same output frame frequency, the prescaler of the MC10B8C module has to be set to twice the
division rate if dither mode is selected; e.g., with the same prescaler division rate the repeat rate of the
output pattern is the same as well as the shortest output pulse with or without dither mode selected.
The DITH bit in control register 0 enables or disables the dither function.
DITH = 0: dither function is disabled.
When DITH is cleared and assuming left aligned operation and RECIRC = 0, the PWM output will start
at a logic low level at the beginning of the PWM period (motor controller timer counter = 0x000). The
PWM output remains low until the motor controller timer counter matches the 11-bit PWM duty cycle
value, DUTY, contained in D[10:0] in MCDCx. When a match (output compare between motor controller
timer counter and DUTY) occurs, the PWM output will toggle to a logic high level and will remain at a
logic high level until the motor controller timer counter overflows (reaches the contents of MCPER – 1).
After the motor controller timer counter resets to 0x000, the PWM output will return to a logic low level.
This completes one PWM period. The PWM period repeats every P counts (as defined by the bits P[10:0]
in the motor controller period register) of the motor controller timer counter. If DUTY >= P, the output
will be static low. If DUTY = 0x0000, the output will be continuously at a logic high level. The
relationship between the motor controller timer counter clock, motor controller timer counter value, and
PWM output while DITH = 0 is shown in Figure 9-17.
Motor Controller
Timer Counter Clock
Motor Controller
Timer Counter
0
100
199 0
100
199 0
PWM Output
1 Period
200 Counts
1 Period
200 Counts
Figure 9-17. PWM Output: DITH = 0, MCAM[1:0] = 01, MCDC = 100,
MCPER = 200, RECIRC = 0
DITH = 1: dither function is enabled
Please note if DITH = 1, the bit P0 in the motor controller period register will be internally forced to 0 and
read always as 0.
When DITH is set and assuming left aligned operation and RECIRC = 0, the PWM output will start at a
logic low level at the beginning of the PWM period (when the motor controller timer counter = 0x000).
The PWM output remains low until the motor controller timer counter matches the 10-bit PWM duty cycle
MC9S12HZ256 Data Sheet, Rev. 2.04
280
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
value, DUTY, contained in D[10:1] in MCDCx. When a match (output compare between motor controller
timer counter and DUTY) occurs, the PWM output will toggle to a logic high level and will remain at a
logic high level until the motor controller timer counter overflows (reaches the value defined by
P[10:1] – 1 in MCPER). After the motor controller timer counter resets to 0x000, the PWM output will
return to a logic low level. This completes the first half of the PWM period. During the second half of the
PWM period, the PWM output will remain at a logic low level until either the motor controller timer
counter matches the 10-bit PWM duty cycle value, DUTY, contained in D[10:1] in MCDCx if D0 = 0, or
the motor controller timer counter matches the 10-bit PWM duty cycle value + 1 (the value of D[10:1] in
MCDCx is increment by 1 and is compared with the motor controller timer counter value) if D0 = 1 in the
corresponding duty cycle register. When a match occurs, the PWM output will toggle to a logic high level
and will remain at a logic high level until the motor controller timer counter overflows (reaches the value
defined by P[10:1] – 1 in MCPER). After the motor controller timer counter resets to 0x000, the PWM
output will return to a logic low level.
This process will repeat every number of counts of the motor controller timer counter defined by the period
register contents (P[10:0]). If the output is neither set to 0% nor to 100% there will be four edges on the
PWM output per PWM period in this case. Therefore, the PWM output compare function will alternate
between DUTY and DUTY + 1 every half PWM period if D0 in the corresponding duty cycle register is
set to 1. The relationship between the motor controller timer counter clock (fTC), motor controller timer
counter value, and left aligned PWM output if DITH = 1 is shown in Figure 9-18 and Figure 9-19.
Figure 9-20 and Figure 9-21 show right aligned and center aligned PWM operation respectively, with
dither feature enabled and D0 = 1. Please note: In the following examples, the MCPER value is defined
by the bits P[10:0], which is, if DITH = 1, always an even number.
NOTE
The DITH bit must be changed only if the motor controller is disabled (all
channels disabled or period register cleared) to avoid erroneous waveforms.
Motor Controller
Timer Counter
Clock
Motor Controller
0
Timer Counter
15
16
99 0
15
16
99 0
PWM Output
1 Period
100 Counts
100 Counts
Figure 9-18. PWM Output: DITH = 1, MCAM[1:0] = 01, MCDC = 31, MCPER = 200, RECIRC = 0
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
281
Chapter 9 Motor Controller (MC10B8CV1)
Motor Controller
Timer Counter
Clock
Motor Controller
Timer Counter
0
16
15
99 0
15
16
99 0
PWM Output
1 Period
100 Counts
100 Counts
Figure 9-19. PWM Output: DITH = 1, MCAM[1:0] = 01, MCDC = 30, MCPER = 200, RECIRC = 0
.
Motor Controller
Timer Counter
Clock
Motor Controller
0
Timer Counter
84
85
99 0
84
85
99 0
PWM Output
1 Period
100 Counts
100 Counts
Figure 9-20. PWM Output: DITH = 1, MCAM[1:0] = 10, MCDC = 31, MCPER = 200, RECIRC = 0
Motor Controller
Timer Counter
Clock
Motor Controller
0
Timer Counter
99 0
15
84
99 0
PWM Output
1 Period
100 Counts
100 Counts
Figure 9-21. PWM Output: DITH = 1, MCAM[1:0] = 11, MCDC = 31, MCPER = 200, RECIRC = 0
MC9S12HZ256 Data Sheet, Rev. 2.04
282
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
9.4.2
PWM Duty Cycle
The PWM duty cycle for the motor controller channel x can be determined by dividing the decimal
representation of bits D[10:0] in MCDCx by the decimal representation of the bits P[10:0] in MCPER and
multiplying the result by 100% as shown in the equation below:
DUTY
Effective PWM Channel X % Duty Cycle = --------------------- ⋅ 100%
MCPER
NOTE
x = PWM Channel Number = 0, 1, 2, 3 ... 8. This equation is only valid if
DUTY <= MCPER and MCPER is not equal to 0.
Whenever D[10:0] >= P[10:0], a constant low level (RECIRC = 0) or high level (RECIRC = 1) will be
output.
9.4.3
Motor Controller Counter Clock Source
Figure 9-22 shows how the PWM motor controller timer counter clock source is selected.
Clock
Generator
Clocks and
Reset
Generator
Module
CLK
Peripheral
Bus
Clock fBUS
Motor Controller
Timer
Counter Clock
Prescaler Select
MPPRE0, MPPRE1
1
1/2
1/4
1/8
Motor Controller Timer
Counter Clock fTC
11-Bit Motor Controller
Timer Counter
Motor Controller Timer
Counter Prescaler
Figure 9-22. Motor Controller Counter Clock Selection
The peripheral bus clock is the source for the motor controller counter prescaler. The motor controller
counter clock rate, fTC, is set by selecting the appropriate prescaler value. The prescaler is selected with
the MCPRE[1:0] bits in motor controller control register 0 (MCCTL0). The motor controller channel
frequency of operation can be calculated using the following formula if DITH = 0:
fTC
Motor Channel Frequency (Hz) = -----------------------------MCPER ⋅ M
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
283
Chapter 9 Motor Controller (MC10B8CV1)
The motor controller channel frequency of operation can be calculated using the following formula if
DITH = 1:
fTC
Motor Channel Frequency (Hz) = ------------------------------------MCPER ⋅ M ⁄ 2
NOTE
Both equations are only valid if MCPER is not equal to 0. M = 1 for left or
right aligned mode, M = 2 for center aligned mode.
Table 9-13 shows examples of the motor controller channel frequencies that can be generated based on
different peripheral bus clock frequencies and the prescaler value.
Table 9-13. Motor Controller Channel Frequencies (Hz),
MCPER = 256, DITH = 0, MCAM = 10, 01
Peripheral Bus Clock Frequency
Prescaler
16 MHz
10 MHz
8 MHz
5 MHz
4 MHz
1
62500
39063
31250
19531
15625
1/2
31250
19531
15625
9766
7813
1/4
15625
9766
7813
4883
3906
1/8
7813
4883
3906
2441
1953
NOTE
Due to the selectable slew rate control of the outputs, clipping may occur on
short output pulses.
9.4.4
Output Switching Delay
In order to prevent large peak current draw from the motor power supply, selectable delays can be used to
stagger the high logic level to low logic level transitions on the motor controller outputs. The timing delay,
td, is determined by the CD[1:0] bits in the corresponding channel control register (MCMCx) and is
selectable between 0, 1, 2, or 3 motor controller timer counter clock cycles.
NOTE
A PWM channel gets disabled at the next timer counter overflow without
notice of the switching delay.
MC9S12HZ256 Data Sheet, Rev. 2.04
284
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
9.4.5
Operation in Wait Mode
During wait mode, the operation of the motor controller pins are selectable between the following two
options:
1. MCSWAI = 1: All module clocks are stopped and the associated port pins are set to their inactive
state, which is defined by the state of the RECIRC bit during wait mode. The motor controller
module registers stay the same as they were prior to entering wait mode. Therefore, after exiting
from wait mode, the associated port pins will resume to the same functionality they had prior to
entering wait mode.
2.
9.4.6
MCSWAI = 0: The PWM clocks continue to run and the associated port pins maintain the
functionality they had prior to entering wait mode both during wait mode and after exiting wait
mode.
Operation in Stop and Pseudo-Stop Modes
All module clocks are stopped and the associated port pins are set to their inactive state, which is defined
by the state of the RECIRC bit. The motor controller module registers stay the same as they were prior to
entering stop or pseudo-stop modes. Therefore, after exiting from stop or pseudo-stop modes, the
associated port pins will resume to the same functionality they had prior to entering stop or pseudo-stop
modes.
9.5
Reset
The motor controller is reset by system reset. All associated ports are released, all registers of the motor
controller module will switch to their reset state as defined in Section 9.3.2, “Register Descriptions”.
9.6
Interrupts
The motor controller has one interrupt source.
9.6.1
Timer Counter Overflow Interrupt
An interrupt will be requested when the MCTOIE bit in the motor controller control register 1 is set and
the running PWM frame is finished. The interrupt is cleared by either setting the MCTOIE bit to 0 or to
write a 1 to the MCTOIF bit in the motor controller control register 0.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
285
Chapter 9 Motor Controller (MC10B8CV1)
9.7
Initialization/Application Information
This section provides an example of how the PWM motor controller can be initialized and used by
application software. The configuration parameters (e.g., timer settings, duty cycle values, etc.) are not
guaranteed to be adequate for any real application.
The example software is implemented in assembly language.
9.7.1
Code Example
One way to use the motor controller is:
1. Perform global initialization
a) Set the motor controller control registers MCCTL0 and MCCTL1 to appropriate values.
i) Prescaler disabled (MCPRE1 = 0, MCPRE0 = 0).
ii) Fast mode and dither disabled (FAST = 0, DITH = 0).
iii) Recirculation feature in dual full H-bridge mode disabled (RECIRC = 0).
All other bits in MCCTL0 and MCCTL1 are set to 0.
b) Configure the channel control registers for the desired mode.
i) Dual full H-bridge mode (MCOM[1:0] = 11).
ii) Left aligned PWM (MCAM[1:0] = 01).
iii) No channel delay (MCCD[1:0] = 00).
2. Perform the startup phase
a) Clear the duty cycle registers MCDC0 and MCDC1
b) Initialize the period register MCPER, which is equivalent to enabling the motor controller.
c) Enable the timer which generates the timebase for the updates of the duty cycle registers.
3. Main program
a) Check if pin PB0 is set to “1” and execute the sub program if a timer interrupt is pending.
b) Initiate the shutdown procedure if pin PB0 is set to “0”.
4. Sub program
a) Update the duty cycle registers
Load the duty cycle registers MCDC0 and MCDC1 with new values from the table and clear
the timer interrupt flag.
The sub program will initiate the shutdown procedure if pin PB0 is set to “0”.
b) Shutdown procedure
The timer is disabled and the duty cycle registers are cleared to drive an inactive value on the PWM output
as long as the motor controller is enabled. The period register is cleared after a certain time, which disables
the motor controller. The table address is restored and the timer interrupt flag is cleared.
MC9S12HZ256 Data Sheet, Rev. 2.04
286
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
;-----------------------------------------------------------------------------------------; Motor Controller (MC10B8C) setup example
;-----------------------------------------------------------------------------------------; Timer defines
;-----------------------------------------------------------------------------------------T_START
EQU $0040
TSCR1
EQU T_START+$06
TFLG2
EQU T_START+$0F
;-----------------------------------------------------------------------------------------; Motor Controller defines
;-----------------------------------------------------------------------------------------MC_START
EQU $0200
MCCTL0
EQU MC_START+$00
MCCTL1
EQU MC_START+$01
MCPER_HI
EQU MC_START+$02
MCPER_LO
EQU MC_START+$03
MCCC0
EQU MC_START+$10
MCCC1
EQU MC_START+$11
MCCC2
EQU MC_START+$12
MCCC3
EQU MC_START+$13
MCDC0_HI
EQU MC_START+$20
MCDC0_LO
EQU MC_START+$21
MCDC1_HI
EQU MC_START+$22
MCDC1_LO
EQU MC_START+$23
MCDC2_HI
EQU MC_START+$24
MCDC2_LO
EQU MC_START+$25
MCDC3_HI
EQU MC_START+$26
MCDC3_LO
EQU MC_START+$27
;-----------------------------------------------------------------------------------------; Port defines
;-----------------------------------------------------------------------------------------DDRB
EQU $0003
PORTB
EQU $0001
;-----------------------------------------------------------------------------------------; Flash defines
;-----------------------------------------------------------------------------------------FLASH_START
EQU $0100
FCMD
EQU FLASH_START+$06
FCLKDIV
EQU FLASH_START+$00
FSTAT
EQU FLASH_START+$05
FTSTMOD
EQU FLASH_START+$02
; Variables
CODE_START
EQU $1000
; start of program code
DTYDAT
EQU $1500
; start of motor controller duty cycle data
TEMP_X
EQU $1700
; save location for IX reg in ISR
TABLESIZE
EQU $1704
; number of config entries in the table
MCPERIOD
EQU $0250
; motor controller period
;-----------------------------------------------------------------------------------------;-----------------------------------------------------------------------------------------ORG
CODE_START
; start of code
LDS
#$1FFF
; set stack pointer
MOVW
#$000A,TABLESIZE
; number of configurations in the table
MOVW
TABLESIZE,TEMP_X
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
287
Chapter 9 Motor Controller (MC10B8CV1)
;-----------------------------------------------------------------------------------------;global motor controller init
;-----------------------------------------------------------------------------------------GLB_INIT: MOVB
#$0000,MCCTL0
; fMC = fBUS, FAST=0, DITH=0
MOVB
#$0000,MCCTL1
; RECIRC=0, MCTOIE=0
MOVW
#$D0D0,MCCC0
; dual full h-bridge mode, left aligned,
; no channel delay
MOVW
#$0000,MCPER_HI
; disable motor controller
;-----------------------------------------------------------------------------------------;motor controller startup
;-----------------------------------------------------------------------------------------STARTUP:
MOVW
#$0000,MCDC0_HI
; define startup duty cycles
MOVW
#$0000,MCDC1_HI
MOVW
#MCPERIOD,MCPER_HI
; define PWM period
MOVB
#$80,TSCR1
; enable timer
MAIN:
LDAA
PORTB
; if PB=0, activate shutdown
ANDA
#$01
BEQ
MN0
JSR
TIM_SR
MN0:
TST
TFLG2
; poll for timer counter overflow flag
BEQ
MAIN
; TOF set?
JSR
TIM_SR
; yes, go to TIM_SR
BRA
MAIN
TIM_SR:
LDX
TEMP_X
; restore index register X
LDAA
PORTB
; if PB=0, enter shutdown routine
ANDA
#$01
BNE
SHUTDOWN
LDX
TEMP_X
; restore index register X
BEQ
NEW_SEQ
; all mc configurations done?
NEW_CFG: LDD
DTYDAT,X
; load new config’s
STD
MCDC0_HI
DEX
DEX
LDD
DTYDAT,X
STD
MCDC1_HI
BRA
END_SR
; leave sub-routine
SHUTDOWN: MOVB
#$00,TSCR1
; disable timer
MOVW
#$0000,MCDC0_HI
; define startup duty cycle
MOVW
#$0000,MCDC1_HI
; define startup duty cycle
LDAA
#$0000
; ensure that duty cycle registers are
; cleared for some time before disabling
; the motor controller
LOOP
DECA
BNE
LOOP
MOVW
#$0000,MCPER_HI
; define pwm period
NEW_SEQ: MOVW
TABLESIZE,TEMP_X
; start new tx loop
LDX
TEMP_X
END_SR:
STX
TEMP_X
; save byte counter
MOVB
#$80,TFLG2
; clear TOF
RTS
; wait for new timer overflow
MC9S12HZ256 Data Sheet, Rev. 2.04
288
Freescale Semiconductor
Chapter 9 Motor Controller (MC10B8CV1)
;-----------------------------------------------------------------------------------------; motor controller duty cycles
;-----------------------------------------------------------------------------------------org
DTYDAT
DC.B
$02, $FF1; MCDC1_HI, MCDC1_LO
DC.B
$02, $D0 ; MCDC0_HI, MCDC0_LO
DC.B
$02, $A0 ; MCDC1_HI, MCDC1_LO
DC.B
$02, $90 ; MCDC0_HI, MCDC0_LO
DC.B
$02, $60 ; MCDC1_HI, MCDC1_LO
DC.B
$02, $25 ; MCDC0_HI, MCDC0_LO
1. The values for the duty cycle table have to be defined for the needs of the target application.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
289
Chapter 9 Motor Controller (MC10B8CV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
290
Freescale Semiconductor
Chapter 10
Stepper Stall Detector (SSDV1)
10.1
Introduction
The stepper stall detector (SSD) block provides a circuit to measure and integrate the induced voltage on
the non-driven coil of a stepper motor using full steps when the gauge pointer is returning to zero (RTZ).
During the RTZ event, the pointer is returned to zero using full steps in either clockwise or counter
clockwise direction, where only one coil is driven at any point in time. The back electromotive force
(EMF) signal present on the non-driven coil is integrated after a blanking time, and its results stored in a
16-bit accumulator. The 16-bit modulus down counter can be used to monitor the blanking time and the
integration time. The value in the accumulator represents the change in linked flux (magnetic flux times
the number of turns in the coil) and can be compared to a stored threshold. Values above the threshold
indicate a moving motor, in which case the pointer can be advanced another full step in the same direction
and integration be repeated. Values below the threshold indicate a stalled motor, thereby marking the
cessation of the RTZ event. The SSD is capable of multiplexing two stepper motors.
10.1.1
•
•
Return to zero modes
— Blanking with no drive
— Blanking with drive
— Conversion
— Integration
Low-power modes
10.1.2
•
•
•
•
•
•
Modes of Operation
Features
Programmable full step state
Programmable integration polarity
Blanking (recirculation) state
16-bit integration accumulator register
16-bit modulus down counter with interrupt
Multiplex two stepper motors
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
291
Chapter 10 Stepper Stall Detector (SSDV1)
10.1.3
Block Diagram
Coil COSx
x = A or B
Coil SINx
VDDM
T3
T1
S1
S3
S2
S4
P
A
D
P
A
D
VSSM
T7
SINxP
SINxM
S5
S7
S6
S8
T6
T4
T2
VDDM
T5
COSxM
COSxP
P
A
D
VDDM
VDDM
T8
VSSM
VSSM
P
A
D
VSSM
reference
integrator
DAC
C1
R1
–
–
+
16-bit accumulator
register
DFF
VDDM
+
R2
16-bit load
register
R2
sigma-delta converter
(analog)
VSSM
4:1 MUX
Bus Clock
1/8
1/2
1/2
1/2
2:1 MUX
16-bit modulus
down counter
1/8
Figure 10-1. SSD Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
292
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
10.2
External Signal Description
Each SSD signal is the output pin of a half bridge, designed to source or sink current. The H-bridge pins
drive the sine and cosine coils of a stepper motor to provide four-quadrant operation. The SSD is capable
of multiplexing between stepper motor A and stepper motor B if two motors are connected.
Table 10-1. Pin Table1
1
10.2.1
Pin Name
Node
Coil
COSxM
Minus
COSx
COSxP
Plus
SINxM
Minus
SINxP
Plus
SINx
x = A or B indicating motor A or motor B
COSxM/COSxP — Cosine Coil Pins for Motor x
These pins interface to the cosine coils of a stepper motor to measure the back EMF for calibration of the
pointer reset position.
10.2.2
SINxM/SINxP — Sine Coil Pins for Motor x
These pins interface to the sine coils of a stepper motor to measure the back EMF for calibration of the
pointer reset position.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
293
Chapter 10 Stepper Stall Detector (SSDV1)
10.3
Memory Map and Register Definition
This section provides a detailed description of all registers of the stepper stall detector (SSD) block.
10.3.1
Module Memory Map
Table 10-2 gives an overview of all registers in the SSD memory map. The SSD occupies eight bytes in
the memory space. The register address results from the addition of base address and address offset. The
base address is determined at the MCU level and is given in the Device Overview chapter. The address
offset is defined at the block level and is given here.
Table 10-2. SSD Memory Map
Address
Offset
10.3.2
Use
Access
0x0000
RTZCTL
R/W
0x0001
MDCCTL
R/W
0x0002
SSDCTL
R/W
0x0003
SSDFLG
R/W
0x0004
MDCCNT (High)
R/W
0x0005
MDCCNT (Low)
R/W
0x0006
ITGACC (High)
R
0x0007
ITGACC (Low)
R
Register Descriptions
This section describes in detail all the registers and register bits in the SSD block. Each description
includes a standard register diagram with an associated figure number. Details of register bit and field
function follow the register diagrams, in bit order.
MC9S12HZ256 Data Sheet, Rev. 2.04
294
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
10.3.2.1
Return-to-Zero Control Register (RTZCTL)
7
6
5
4
ITG
DCOIL
RCIR
POL
0
0
0
0
R
3
2
1
0
0
SMS
STEP
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 10-2. Return-to-Zero Control Register (RTZCTL)
Read: anytime
Write: anytime
Table 10-3. RTZCTL Field Descriptions
Field
Description
7
ITG
Integration — During return to zero (RTZE = 1), one of the coils must be recirculated or non-driven determined
by the STEP field. If the ITG bit is set, the coil is non-driven, and if the ITG bit is clear, the coil is being recirculated.
Table 10-4 shows the condition state of each transistor from Figure 10-1 based on the STEP, ITG, DCOIL and
RCIR bits.
Regardless of the RTZE bit value, if the ITG bit is set, one end of the non-driven coil connects to the (non-zero)
reference input and the other end connects to the integrator input of the sigma-delta converter. Regardless of
the RTZE bit value, if the ITG bit is clear, the non-driven coil is in a blanking state, the converter is in a reset state,
and the accumulator is initialized to zero. Table 10-5 shows the condition state of each switch from Figure 10-1
based on the ITG, STEP and POL bits.
0 Blanking
1 Integration
6
DCOIL
Drive Coil — During return to zero (RTZE=1), one of the coils must be driven determined by the STEP field. If
the DCOIL bit is set, this coil is driven. If the DCOIL bit is clear, this coil is disconnected or drivers turned off.
Table 10-4 shows the condition state of each transistor from Figure 10-1 based on the STEP, ITG, DCOIL and
RCIR bits.
0 Disconnect Coil
1 Drive Coil
5
RCIR
Recirculation in Blanking Mode — During return to zero (RTZE = 1), one of the coils is recirculated prior to
integration during the blanking period. This bit determines if the coil is recirculated via VDDM or via VSSM.
Table 10-4 shows the condition state of each transistor from Figure 10-1 based on the STEP, ITG, DCOIL and
RCIR bits.
0 Recirculation on the high side transistors
1 Recirculation on the low side transistors
4
POL
Polarity — This bit determines which end of the non-driven coil is routed to the sigma-delta converter during
conversion or integration mode. Table 10-5 shows the condition state of each switch from Figure 10-1 based on
the ITG, STEP and POL bits.
2
SMS
Stepper Motor Select — This bit selects one of two possible stepper motors to be used for stall detection. See
top level chip description for the stepper motor assignments to the SSD.
0 Stepper Motor A is selected for stall detection
1 Stepper Motor B is selected for stall detection
1:0
STEP
Full Step State — This field indicates one of the four possible full step states. Step 0 is considered the east pole
or 0° angle, step 1 is the north Pole or 90° angle, step 2 is the west pole or 180° angle, and step 3 is the south
pole or 270° angle. For each full step state, Table 10-6 shows the current through each of the two coils, and the
coil nodes that are multiplexed to the sigma-delta converter during conversion or integration mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
295
Chapter 10 Stepper Stall Detector (SSDV1)
Table 10-4. Transistor Condition States (RTZE = 1)
STEP
ITG
DCOIL
RCIR
T1
T2
T3
T4
T5
T6
T7
T8
xx
1
0
x
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
00
0
0
0
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
00
0
0
1
OFF
OFF
OFF
OFF
OFF
ON
OFF
ON
00
0
1
0
ON
OFF
OFF
ON
ON
OFF
ON
OFF
00
0
1
1
ON
OFF
OFF
ON
OFF
ON
OFF
ON
00
1
1
x
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
01
0
0
0
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
01
0
0
1
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
01
0
1
0
ON
OFF
ON
OFF
ON
OFF
OFF
ON
01
0
1
1
OFF
ON
OFF
ON
ON
OFF
OFF
ON
01
1
1
x
OFF
OFF
OFF
OFF
ON
OFF
OFF
ON
10
0
0
0
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
10
0
0
1
OFF
OFF
OFF
OFF
OFF
ON
OFF
ON
10
0
1
0
OFF
ON
ON
OFF
ON
OFF
ON
OFF
10
0
1
1
OFF
ON
ON
OFF
OFF
ON
OFF
ON
10
1
1
x
OFF
ON
ON
OFF
OFF
OFF
OFF
OFF
11
0
0
0
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
11
0
0
1
OFF
ON
OFF
ON
OFF
OFF
OFF
OFF
11
0
1
0
ON
OFF
ON
OFF
OFF
ON
ON
OFF
11
0
1
1
OFF
ON
OFF
ON
OFF
ON
ON
OFF
11
1
1
x
OFF
OFF
OFF
OFF
OFF
ON
ON
OFF
Table 10-5. Switch Condition States (RTZE = 1 or 0)
ITG
STEP
POL
S1
S2
S3
S4
S5
S6
S7
S8
0
xx
x
Open
Open
Open
Open
Open
Open
Open
Open
1
00
0
Open
Open
Open
Open
Close
Open
Open
Close
1
00
1
Open
Open
Open
Open
Open
Close
Close
Open
1
01
0
Open
Close
Close
Open
Open
Open
Open
Open
1
01
1
Close
Open
Open
Close
Open
Open
Open
Open
1
10
0
Open
Open
Open
Open
Open
Close
Close
Open
1
10
1
Open
Open
Open
Open
Close
Open
Open
Close
1
11
0
Close
Open
Open
Close
Open
Open
Open
Open
1
11
1
Open
Close
Close
Open
Open
Open
Open
Open
MC9S12HZ256 Data Sheet, Rev. 2.04
296
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
Table 10-6. Full Step States
COSINE
Coil Current
STEP Pole
Coil Node to
Integrator input
(Close Switch)
SINE
Coil Current
Angle
DCOIL = 0 DCOIL = 1 DCOIL = 0 DCOIL = 1
0
East
0°
0
+ I max
0
0
1
North
90°
0
0
0
+ I max
2
West
180°
0
– I max
0
0
3
South
270°
0
0
0
– I max
10.3.2.2
ITG = 1
POL = 0
ITG = 1
POL = 1
ITG = 1
POL = 0
ITG = 1
POL = 1
SINxM (S8)
SINxP (S6)
SINxP (S5)
SINxM (S7)
COSxP (S2) COSxM (S4) COSxM (S3) COSxP (S1)
SINxP (S6)
SINxM (S8)
SINxM (S7)
SINxP (S5)
COSxM (S4) COSxP (S2) COSxP (S1) COSxM (S3)
Modulus Down Counter Control Register (MDCCTL)
7
6
5
4
MCZIE
MODMC
RDMCL
PRE
R
3
2
0
W
Reset
Coil Node to
Reference input
(Close Switch)
1
0
0
MCEN
AOVIE
FLMC
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-3. Modulus Down Counter Control Register (MDCCTL)
Read: anytime
Write: anytime.
l
Table 10-7. MDCCTL Field Descriptions
Field
Description
7
MCZIE
Modulus Counter Underflow Interrupt Enable
0 Interrupt disabled.
1 Interrupt enabled. An interrupt will be generated when the modulus counter underflow interrupt flag (MCZIF)
is set.
6
MODMC
Modulus Mode Enable
0 The modulus counter counts down from the value in the counter register and will stop at 0x0000.
1 Modulus mode is enabled. When the counter reaches 0x0000, the counter is loaded with the latest value
written to the modulus counter register.
Note: For proper operation, the MCEN bit should be cleared before modifying the MODMC bit in order to reset
the modulus counter to 0xFFFF.
5
RDMCL
Read Modulus Down-Counter Load
0 Reads of the modulus count register (MDCCNT) will return the present value of the count register.
1 Reads of the modulus count register (MDCCNT) will return the contents of the load register.
4
PRE
Prescaler
0 The modulus down counter clock frequency is the bus frequency divided by 64.
1 The modulus down counter clock frequency is the bus frequency divided by 512.
Note: A change in the prescaler division rate will not be effective until a load of the load register into the modulus
counter count register occurs.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
297
Chapter 10 Stepper Stall Detector (SSDV1)
Table 10-7. MDCCTL Field Descriptions (continued)
Field
Description
3
FLMC
Force Load Register into the Modulus Counter Count Register — This bit always reads zero.
0 Write zero to this bit has no effect.
1 Write one into this bit loads the load register into the modulus counter count register.
2
MCEN
Modulus Down-Counter Enable
0 Modulus down-counter is disabled. The modulus counter (MDCCNT) is preset to 0xFFFF. This will prevent an
early interrupt flag when the modulus down-counter is enabled.
1 Modulus down-counter is enabled.
0
AOVIE
Accumulator Overflow Interrupt Enable
0 Interrupt disabled.
1 Interrupt enabled. An interrupt will be generated when the accumulator overflow interrupt flag (AOVIF) is set.
10.3.2.3
Stepper Stall Detector Control Register (SSDCTL)
7
6
5
4
RTZE
SDCPU
SSDWAI
FTST
0
0
0
0
R
3
2
0
0
1
0
ACLKS
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 10-4. Stepper Stall Detector Control Register (SSDCTL)
Read: anytime
Write: anytime
l
Table 10-8. SSDCTL Field Descriptions
Field
Description
7
RTZE
Return to Zero Enable — If this bit is set, the coils are controlled by the SSD and are configured into one of the
four full step states as shown in Table 10-6. If this bit is cleared, the coils are not controlled by the SSD.
0 RTZ is disabled.
1 RTZ is enabled.
6
SDCPU
Sigma-Delta Converter Power Up — This bit provides on/off control for the sigma-delta converter allowing
reduced MCU power consumption. Because the analog circuit is turned off when powered down, the sigma-delta
converter requires a recovery time after it is powered up.
0 Sigma-delta converter is powered down.
1 Sigma-delta converter is powered up.
5
SSDWAI
SSD Disabled during Wait Mode — When entering Wait Mode, this bit provides on/off control over the SSD
allowing reduced MCU power consumption. Because the analog circuit is turned off when powered down, the
sigma-delta converter requires a recovery time after exit from Wait Mode.
0 SSD continues to run in WAIT mode.
1 Entering WAIT mode freezes the clock to the prescaler divider, powers down the sigma-delta converter, and
if RTZE bit is set, the sine and cosine coils are recirculated via VSSM.
MC9S12HZ256 Data Sheet, Rev. 2.04
298
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
Table 10-8. SSDCTL Field Descriptions (continued)
Field
4
FTST
1:0
ACLKS
Description
Factory Test — This bit is reserved for factory test and reads zero in user mode.
Accumulator Sample Frequency Select — This field sets the accumulator sample frequency by pre-scaling
the bus frequency by a factor of 8, 16, 32, or 64. A faster sample frequency can provide more accurate results
but cause the accumulator to overflow. Best results are achieved with a frequency between 500 kHz and 2 MHz.
Accumulator Sample Frequency = fBUS / (8 x 2ACLKS)
Table 10-9. Accumulator Sample Frequency
ACLKS
Frequency
fBUS = 40
MHz
fBUS = 25
MHz
fBUS = 16
MHz
0
fBUS / 8
5.00 MHz
3.12 MHz
2.00 MHz
1
fBUS / 16
2.50 MHz
1.56 MHz
1.00 MHz
2
fBUS / 32
1.25 MHz
781 kHz
500 kHz
3
fBUS / 64
625 kHz
391 kHz
250 kHz
NOTE
A change in the accumulator sample frequency will not be effective until the
ITG bit is cleared.
10.3.2.4
Stepper Stall Detector Flag Register (SSDFLG)
7
R
6
5
4
3
2
1
0
0
0
0
0
0
MCZIF
0
AOVIF
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-5. Stepper Stall Detector Flag Register (SSDFLG)
Read: anytime
Write: anytime.
l
Table 10-10. SSDFLG Field Descriptions
Field
Description
7
MCZIF
Modulus Counter Underflow Interrupt Flag — This flag is set when the modulus down-counter reaches
0x0000. If not masked (MCZIE = 1), a modulus counter underflow interrupt is pending while this flag is set. This
flag is cleared by writing a ‘1’ to the bit. A write of ‘0’ has no effect.
0
AOVIF
Accumulator Overflow Interrupt Flag — This flag is set when the Integration Accumulator has a positive or
negative overflow. If not masked (AOVIE = 1), an accumulator overflow interrupt is pending while this flag is set.
This flag is cleared by writing a ‘1’ to the bit. A write of ‘0’ has no effect.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
299
Chapter 10 Stepper Stall Detector (SSDV1)
10.3.2.5
Modulus Down-Counter Count Register (MDCCNT)
15
14
13
12
11
10
9
8
1
1
1
1
R
MDCCNT
W
Reset
1
1
1
1
Figure 10-6. Modulus Down-Counter Count Register High (MDCCNT)
7
6
5
4
3
2
1
0
1
1
1
1
R
MDCCNT
W
Reset
1
1
1
1
Figure 10-7. Modulus Down-Counter Count Register Low (MDCCNT)
Read: anytime
Write: anytime.
NOTE
A separate read/write for high byte and low byte gives a different result than
accessing the register as a word.
If the RDMCL bit in the MDCCTL register is cleared, reads of the MDCCNT register will return the
present value of the count register. If the RDMCL bit is set, reads of the MDCCNT register will return the
contents of the load register.
With a 0x0000 write to the MDCCNT register, the modulus counter stays at zero and does not set the
MCZIF flag in the SSDFLG register.
If modulus mode is not enabled (MODMC = 0), a write to the MDCCNT register immediately updates the
load register and the counter register with the value written to it. The modulus counter will count down
from this value and will stop at 0x0000.
If modulus mode is enabled (MODMC = 1), a write to the MDCCNT register updates the load register with
the value written to it. The count register will not be updated with the new value until the next counter
underflow. The FLMC bit in the MDCCTL register can be used to immediately update the count register
with the new value if an immediate load is desired.
The modulus down counter clock frequency is the bus frequency divided by 64 or 512.
MC9S12HZ256 Data Sheet, Rev. 2.04
300
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
10.3.2.6
Integration Accumulator Register (ITGACC)
15
14
13
12
R
11
10
9
8
0
0
0
0
ITGACC
W
Reset
0
0
0
0
Figure 10-8. Integration Accumulator Register High (ITGACC)
7
6
5
4
R
3
2
1
0
0
0
0
0
ITGACC
W
Reset
0
0
0
0
Figure 10-9. Integration Accumulator Register Low (ITGACC)
Read: anytime.
Write: Never.
NOTE
A separate read for high byte and low byte gives a different result than
accessing the register as a word.
This 16-bit field is signed and is represented in two’s complement. It indicates the change in flux while
integrating the back EMF present in the non-driven coil during a return to zero event.
When ITG is zero, the accumulator is initialized to 0x0000 and the sigma-delta converter is in a reset state.
When ITG is one, the accumulator increments or decrements depending on the sigma-delta conversion
sample. The accumulator sample frequency is determined by the ACLKS field. The accumulator freezes
at 0x7FFF on a positive overflow and freezes at 0x8000 on a negative overflow.
10.4
Functional Description
The stepper stall detector (SSD) has a simple control block to configure the H-bridge drivers of a stepper
motor in four different full step states with four available modes during a return to zero event. The SSD
has a detect circuit using a sigma-delta converter to measure and integrate changes in flux of the
de-energized winding in the stepping motor and the conversion result is accumulated in a 16-bit signed
register. The SSD also has a 16-bit modulus down counter to monitor blanking and integration times. DC
offset compensation is implemented when using the modulus down counter to monitor integration times.
10.4.1
Return to Zero Modes
There are four return to zero modes as shown in Table 10-11.
Table 10-11. Return to Zero Modes
ITG
DCOIL
Mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
301
Chapter 10 Stepper Stall Detector (SSDV1)
Table 10-11. Return to Zero Modes
10.4.1.1
0
0
Blanking with no drive
0
1
Blanking with drive
1
0
Conversion
1
1
Integration
Blanking with No Drive
In blanking mode with no drive, one of the coils is masked from the sigma-delta converter, and if RTZ is
enabled (RTZE = 1), it is set up to recirculate its current. If RTZ is enabled (RTZE = 1), the other coil is
disconnected to prevent any loss of flux change that would occur when the motor starts moving before the
end of recirculation and start of integration. In blanking mode with no drive, the accumulator is initialized
to 0x0000 and the converter is in a reset state.
10.4.1.2
Blanking with Drive
In blanking mode with drive, one of the coils is masked from the sigma-delta converter, and if RTZ is
enabled (RTZE = 1), it is set up to recirculate its current. If RTZ is enabled (RTZE = 1), the other coil is
driven. In blanking mode with drive, the accumulator is initialized to 0x0000 and the converter is in a reset
state.
10.4.1.3
Conversion
In conversion mode, one of the coils is routed for integration with one end connected to the (non-zero)
reference input and the other end connected to the integrator input of the sigma-delta converter. If RTZ is
enabled (RTZE=1), both coils are disconnected. This mode is not useful for stall detection.
10.4.1.4
Integration
In integration mode, one of the coils is routed for integration with one end connected to the (non-zero)
reference input and the other end connected to the integrator input of the sigma-delta converter. If RTZ is
enabled (RTZE = 1), the other coil is driven. This mode is used to rectify and integrate the back EMF
produced by the coils to detect stepped rotary motion.
DC offset compensation is implemented when using the modulus down counter to monitor integration
time.
10.4.2
Full Step States
During a return to zero (RTZ) event, the stepper motor pointer requires a 90° full motor electrical step with
full amplitude pulses applied to each phase in turn. For counter clockwise rotation (CCW), the STEP value
is incremented 0, 1, 2, 3, 0 and so on, and for a clockwise rotation the STEP value is decremented 3, 2, 1,
0 and so on. Figure 10-10 shows the current level through each coil for each full step in CCW rotation
when DCOIL is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
302
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
+ Imax
SINE COIL
CURRENT
0
_ Imax
Recirculation
+ Imax
COSINE COIL
CURRENT
0
_ Imax
1
0
2
3
Figure 10-10. Full Steps (CCW)
Figure 10-11 shows the current flow in the SINx and COSx H-bridges when STEP = 0, DCOIL = 1,
ITG = 0 and RCIR = 0.
VDDM
VDDM
T3
T1
COSxP
COSxM
T2
T4
T7
T5
SINxP
SINxM
T6
VSSM
T8
VSSM
Figure 10-11. Current Flow when STEP = 0, DCOIL = 1, ITG = 0, RCIR = 0
Figure 10-12 shows the current flow in the SINx and COSx H-bridges when STEP = 1, DCOIL = 1,
ITG = 0 and RCIR = 1.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
303
Chapter 10 Stepper Stall Detector (SSDV1)
VDDM
VDDM
T3
T1
COSxP
COSxM
T2
T4
T7
T5
SINxP
SINxM
T6
VSSM
T8
VSSM
Figure 10-12. Current Flow when STEP = 1, DCOIL = 1, ITG = 0, RCIR = 1
Figure 10-13 shows the current flow in the SINx and COSx H-bridges when STEP = 2, DCOIL = 1 and
ITG = 1.
VDDM
VDDM
T3
T1
COSxP
COSxM
T2
T4
T7
T5
SINxP
SINxM
T6
VSSM
T8
VSSM
Figure 10-13. Current flow when STEP = 2, DCOIL = 1, ITG = 1
Figure 10-14 shows the current flow in the SINx and COSx H-bridges when STEP = 3, DCOIL = 1 and
ITG = 1.
MC9S12HZ256 Data Sheet, Rev. 2.04
304
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
VDDM
VDDM
T3
T1
COSxP
COSxM
T2
T4
T7
T5
SINxP
SINxM
T6
VSSM
T8
VSSM
Figure 10-14. Current flow when STEP = 3, DCOIL = 1, ITG = 1
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
305
Chapter 10 Stepper Stall Detector (SSDV1)
10.4.3
Operation in Low Power Modes
The SSD block can be configured for lower MCU power consumption in three different ways.
• Stop mode powers down the sigma-delta converter and halts clock to the modulus counter. Exit
from Stop enables the sigma-delta converter and the clock to the modulus counter but due to the
converter recovery time, the integration result should be ignored.
• Wait mode with SSDWAI bit set powers down the sigma-delta converter and halts the clock to the
modulus counter. Exit from Wait enables the sigma-delta converter and clock to the modulus
counter but due to the converter recovery time, the integration result should be ignored.
• Clearing SDCPU bit powers down the sigma-delta converter.
10.4.4
Stall Detection Flow
Figure 10-15 shows a flowchart and software setup for stall detection of a stepper motor. To control a
second stepper motor, the SMS bit must be toggled during the SSD initialization.
MC9S12HZ256 Data Sheet, Rev. 2.04
306
Freescale Semiconductor
Chapter 10 Stepper Stall Detector (SSDV1)
Using Motor Control module, drive pointer to within 3 full steps of
calibrated zero position.
Advance Pointer
Initialize SSD
1. Clear (or set) RCIR; clear (or set) POL; clear (or set) SMS;
2. Set MCZIE; clear MODMC; clear (or set) PRE; set MCEN.
3. Set RTZE; set SDCPU; write ACLKS (select sample frequency).
4. Store threshold value in RAM.
Start Blanking
1. Clear MCZIF.
2. Write MDCCNT with blanking time value.
3. Clear ITG; clear (or set) DCOIL; increment (or decrement) STEP for
CCW (or CW) motion.
End of
Blanking?
MDCCNT = 0x0000? or MCZIF = 1?
No
Yes
1. Clear MCZIF.
2. Write MDCCNT with integration time value.
3. Set ITG; set DCOIL.
Start Integration
End of
Integration?
MDCCNT = 0x0000? or MCZIF = 1?
No
Yes
No
Stall
Detection?
ITGACC < Threshold (RAM value)?
Yes
Disable SSD
1. Clear MCZIF.
2. Clear MCEN.
3. Clear ITG.
4. Clear RTZE; clear SDCPU.
Figure 10-15. Return-to-Zero Flowchart
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
307
Chapter 10 Stepper Stall Detector (SSDV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
308
Freescale Semiconductor
Chapter 11
Inter-Integrated Circuit (IICV2)
11.1
Introduction
The inter-IC bus (IIC) is a two-wire, bidirectional serial bus that provides a simple, efficient method of data
exchange between devices. Being a two-wire device, the IIC bus minimizes the need for large numbers of
connections between devices, and eliminates the need for an address decoder.
This bus is suitable for applications requiring occasional communications over a short distance between a
number of devices. It also provides flexibility, allowing additional devices to be connected to the bus for
further expansion and system development.
The interface is designed to operate up to 100 kbps with maximum bus loading and timing. The device is
capable of operating at higher baud rates, up to a maximum of clock/20, with reduced bus loading. The
maximum communication length and the number of devices that can be connected are limited by a
maximum bus capacitance of 400 pF.
11.1.1
Features
The IIC module has the following key features:
• Compatible with I2C bus standard
• Multi-master operation
• Software programmable for one of 256 different serial clock frequencies
• Software selectable acknowledge bit
• Interrupt driven byte-by-byte data transfer
• Arbitration lost interrupt with automatic mode switching from master to slave
• Calling address identification interrupt
• Start and stop signal generation/detection
• Repeated start signal generation
• Acknowledge bit generation/detection
• Bus busy detection
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
309
Chapter 11 Inter-Integrated Circuit (IICV2)
11.1.2
Modes of Operation
The IIC functions the same in normal, special, and emulation modes. It has two low power modes: wait
and stop modes.
11.1.3
Block Diagram
The block diagram of the IIC module is shown in Figure 11-1.
IIC
Registers
Start
Stop
Arbitration
Control
Clock
Control
In/Out
Data
Shift
Register
Interrupt
bus_clock
SCL
SDA
Address
Compare
Figure 11-1. IIC Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
310
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
11.2
External Signal Description
The IIC module has two external pins.
11.2.1
IIC_SCL — Serial Clock Line Pin
This is the bidirectional serial clock line (SCL) of the module, compatible to the IIC bus specification.
11.2.2
IIC_SDA — Serial Data Line Pin
This is the bidirectional serial data line (SDA) of the module, compatible to the IIC bus specification.
11.3
Memory Map and Register Definition
This section provides a detailed description of all memory and registers for the IIC module.
11.3.1
Module Memory Map
The memory map for the IIC module is given below in Table 11-1. The address listed for each register is
the address offset.The total address for each register is the sum of the base address for the IIC module and
the address offset for each register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
311
Chapter 11 Inter-Integrated Circuit (IICV2)
11.3.2
Register Descriptions
This section consists of register descriptions in address order. Each description includes a standard register
diagram with an associated figure number. Details of register bit and field function follow the register
diagrams, in bit order.
Register
Name
IBAD
R
W
IBFD
R
W
IBCR
R
W
IBSR
R
Bit 7
6
5
4
3
2
1
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
IBC7
IBC6
IBC5
IBC4
IBC3
IBC2
IBC1
IBEN
IBIE
MS/SL
Tx/Rx
TXAK
0
0
TCF
IAAS
IBB
D7
D6
D5
IBAL
W
IBDR
R
W
D4
RSTA
0
SRW
D3
D2
IBIF
D1
Bit 0
0
IBC0
IBSWAI
RXAK
D0
= Unimplemented or Reserved
Table 11-1. IIC Register Summary
11.3.2.1
IIC Address Register (IBAD)
7
6
5
4
3
2
1
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
0
0
0
0
0
0
0
R
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 11-2. IIC Bus Address Register (IBAD)
Read and write anytime
This register contains the address the IIC bus will respond to when addressed as a slave; note that it is not
the address sent on the bus during the address transfer.
Table 11-2. IBAD Field Descriptions
Field
Description
7:1
ADR[7:1]
Slave Address — Bit 1 to bit 7 contain the specific slave address to be used by the IIC bus module.The default
mode of IIC bus is slave mode for an address match on the bus.
0
Reserved
Reserved — Bit 0 of the IBAD is reserved for future compatibility. This bit will always read 0.
MC9S12HZ256 Data Sheet, Rev. 2.04
312
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
11.3.2.2
IIC Frequency Divider Register (IBFD)
7
6
5
4
3
2
1
0
IBC7
IBC6
IBC5
IBC4
IBC3
IBC2
IBC1
IBC0
0
0
0
0
0
0
0
0
R
W
Reset
= Unimplemented or Reserved
Figure 11-3. IIC Bus Frequency Divider Register (IBFD)
Read and write anytime
Table 11-3. IBFD Field Descriptions
Field
Description
7:0
IBC[7:0]
I Bus Clock Rate 7:0 — This field is used to prescale the clock for bit rate selection. The bit clock generator is
implemented as a prescale divider — IBC7:6, prescaled shift register — IBC5:3 select the prescaler divider and
IBC2-0 select the shift register tap point. The IBC bits are decoded to give the tap and prescale values as shown
in Table 11-4.
Table 11-4. I-Bus Tap and Prescale Values
IBC2-0
(bin)
SCL Tap
(clocks)
SDA Tap
(clocks)
000
5
1
001
6
1
010
7
2
011
8
2
100
9
3
101
10
3
110
12
4
111
15
4
IBC5-3
(bin)
scl2start
(clocks)
scl2stop
(clocks)
scl2tap
(clocks)
tap2tap
(clocks)
000
2
7
4
1
001
2
7
4
2
010
2
9
6
4
011
6
9
6
8
100
14
17
14
16
101
30
33
30
32
110
62
65
62
64
111
126
129
126
128
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
313
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-5. Multiplier Factor
IBC7-6
MUL
00
01
01
02
10
04
11
RESERVED
The number of clocks from the falling edge of SCL to the first tap (Tap[1]) is defined by the values shown
in the scl2tap column of Table 11-4, all subsequent tap points are separated by 2IBC5-3 as shown in the
tap2tap column in Table 11-4. The SCL Tap is used to generated the SCL period and the SDA Tap is used
to determine the delay from the falling edge of SCL to SDA changing, the SDA hold time.
IBC7–6 defines the multiplier factor MUL. The values of MUL are shown in the Table 11-5.
SCL Divider
SCL
SDA Hold
SDA
SDA
SCL Hold(stop)
SCL Hold(start)
SCL
START condition
STOP condition
Figure 11-4. SCL Divider and SDA Hold
The equation used to generate the divider values from the IBFD bits is:
SCL Divider = MUL x {2 x (scl2tap + [(SCL_Tap -1) x tap2tap] + 2)}
MC9S12HZ256 Data Sheet, Rev. 2.04
314
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
The SDA hold delay is equal to the CPU clock period multiplied by the SDA Hold value shown in
Table 11-6. The equation used to generate the SDA Hold value from the IBFD bits is:
SDA Hold = MUL x {scl2tap + [(SDA_Tap - 1) x tap2tap] + 3}
The equation for SCL Hold values to generate the start and stop conditions from the IBFD bits is:
SCL Hold(start) = MUL x [scl2start + (SCL_Tap - 1) x tap2tap]
SCL Hold(stop) = MUL x [scl2stop + (SCL_Tap - 1) x tap2tap]
Table 11-6. IIC Divider and Hold Values (Sheet 1 of 5)
IBC[7:0]
(hex)
SCL Divider
(clocks)
SDA Hold
(clocks)
SCL Hold
(start)
SCL Hold
(stop)
20
22
24
26
28
30
34
40
28
32
36
40
44
48
56
68
48
56
64
72
80
88
104
128
80
96
112
128
144
160
192
240
160
192
224
7
7
8
8
9
9
10
10
7
7
9
9
11
11
13
13
9
9
13
13
17
17
21
21
9
9
17
17
25
25
33
33
17
17
33
6
7
8
9
10
11
13
16
10
12
14
16
18
20
24
30
18
22
26
30
34
38
46
58
38
46
54
62
70
78
94
118
78
94
110
11
12
13
14
15
16
18
21
15
17
19
21
23
25
29
35
25
29
33
37
41
45
53
65
41
49
57
65
73
81
97
121
81
97
113
MUL=1
00
01
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F
10
11
12
13
14
15
16
17
18
19
1A
1B
1C
1D
1E
1F
20
21
22
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
315
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-6. IIC Divider and Hold Values (Sheet 2 of 5)
IBC[7:0]
(hex)
SCL Divider
(clocks)
SDA Hold
(clocks)
SCL Hold
(start)
SCL Hold
(stop)
23
24
25
26
27
28
29
2A
2B
2C
2D
2E
2F
30
31
32
33
34
35
36
37
38
39
3A
3B
3C
3D
3E
3F
256
288
320
384
480
320
384
448
512
576
640
768
960
640
768
896
1024
1152
1280
1536
1920
1280
1536
1792
2048
2304
2560
3072
3840
33
49
49
65
65
33
33
65
65
97
97
129
129
65
65
129
129
193
193
257
257
129
129
257
257
385
385
513
513
126
142
158
190
238
158
190
222
254
286
318
382
478
318
382
446
510
574
638
766
958
638
766
894
1022
1150
1278
1534
1918
129
145
161
193
241
161
193
225
257
289
321
385
481
321
385
449
513
577
641
769
961
641
769
897
1025
1153
1281
1537
1921
40
41
42
43
44
45
46
47
48
49
4A
4B
4C
4D
4E
40
44
48
52
56
60
68
80
56
64
72
80
88
96
112
14
14
16
16
18
18
20
20
14
14
18
18
22
22
26
12
14
16
18
20
22
26
32
20
24
28
32
36
40
48
22
24
26
28
30
32
36
42
30
34
38
42
46
50
58
MUL=2
MC9S12HZ256 Data Sheet, Rev. 2.04
316
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-6. IIC Divider and Hold Values (Sheet 3 of 5)
IBC[7:0]
(hex)
SCL Divider
(clocks)
SDA Hold
(clocks)
SCL Hold
(start)
SCL Hold
(stop)
4F
50
51
52
53
54
55
56
57
58
59
5A
5B
5C
5D
5E
5F
60
61
62
63
64
65
66
67
68
69
6A
6B
6C
6D
6E
6F
70
71
72
73
74
75
76
77
78
79
7A
7B
136
96
112
128
144
160
176
208
256
160
192
224
256
288
320
384
480
320
384
448
512
576
640
768
960
640
768
896
1024
1152
1280
1536
1920
1280
1536
1792
2048
2304
2560
3072
3840
2560
3072
3584
4096
26
18
18
26
26
34
34
42
42
18
18
34
34
50
50
66
66
34
34
66
66
98
98
130
130
66
66
130
130
194
194
258
258
130
130
258
258
386
386
514
514
258
258
514
514
60
36
44
52
60
68
76
92
116
76
92
108
124
140
156
188
236
156
188
220
252
284
316
380
476
316
380
444
508
572
636
764
956
636
764
892
1020
1148
1276
1532
1916
1276
1532
1788
2044
70
50
58
66
74
82
90
106
130
82
98
114
130
146
162
194
242
162
194
226
258
290
322
386
482
322
386
450
514
578
642
770
962
642
770
898
1026
1154
1282
1538
1922
1282
1538
1794
2050
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
317
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-6. IIC Divider and Hold Values (Sheet 4 of 5)
IBC[7:0]
(hex)
SCL Divider
(clocks)
SDA Hold
(clocks)
SCL Hold
(start)
SCL Hold
(stop)
7C
7D
7E
7F
4608
5120
6144
7680
770
770
1026
1026
2300
2556
3068
3836
2306
2562
3074
3842
80
81
82
83
84
85
86
87
88
89
8A
8B
8C
8D
8E
8F
90
91
92
93
94
95
96
97
98
99
9A
9B
9C
9D
9E
9F
A0
A1
A2
A3
A4
A5
A6
A7
80
88
96
104
112
120
136
160
112
128
144
160
176
192
224
272
192
224
256
288
320
352
416
512
320
384
448
512
576
640
768
960
640
768
896
1024
1152
1280
1536
1920
28
28
32
32
36
36
40
40
28
28
36
36
44
44
52
52
36
36
52
52
68
68
84
84
36
36
68
68
100
100
132
132
68
68
132
132
196
196
260
260
24
28
32
36
40
44
52
64
40
48
56
64
72
80
96
120
72
88
104
120
136
152
184
232
152
184
216
248
280
312
376
472
312
376
440
504
568
632
760
952
44
48
52
56
60
64
72
84
60
68
76
84
92
100
116
140
100
116
132
148
164
180
212
260
164
196
228
260
292
324
388
484
324
388
452
516
580
644
772
964
MUL=4
MC9S12HZ256 Data Sheet, Rev. 2.04
318
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-6. IIC Divider and Hold Values (Sheet 5 of 5)
IBC[7:0]
(hex)
SCL Divider
(clocks)
SDA Hold
(clocks)
SCL Hold
(start)
SCL Hold
(stop)
A8
A9
AA
AB
AC
AD
AE
AF
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
BA
BB
BC
BD
BE
BF
1280
1536
1792
2048
2304
2560
3072
3840
2560
3072
3584
4096
4608
5120
6144
7680
5120
6144
7168
8192
9216
10240
12288
15360
132
132
260
260
388
388
516
516
260
260
516
516
772
772
1028
1028
516
516
1028
1028
1540
1540
2052
2052
632
760
888
1016
1144
1272
1528
1912
1272
1528
1784
2040
2296
2552
3064
3832
2552
3064
3576
4088
4600
5112
6136
7672
644
772
900
1028
1156
1284
1540
1924
1284
1540
1796
2052
2308
2564
3076
3844
2564
3076
3588
4100
4612
5124
6148
7684
11.3.2.3
IIC Control Register (IBCR)
7
6
5
4
3
IBEN
IBIE
MS/SL
Tx/Rx
TXAK
R
1
0
0
0
IBSWAI
RSTA
W
Reset
2
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-5. IIC Bus Control Register (IBCR)
Read and write anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
319
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-7. IBCR Field Descriptions
Field
Description
7
IBEN
I-Bus Enable — This bit controls the software reset of the entire IIC bus module.
0 The module is reset and disabled. This is the power-on reset situation. When low the interface is held in reset
but registers can be accessed
1 The IIC bus module is enabled.This bit must be set before any other IBCR bits have any effect
If the IIC bus module is enabled in the middle of a byte transfer the interface behaves as follows: slave mode
ignores the current transfer on the bus and starts operating whenever a subsequent start condition is detected.
Master mode will not be aware that the bus is busy, hence if a start cycle is initiated then the current bus cycle
may become corrupt. This would ultimately result in either the current bus master or the IIC bus module losing
arbitration, after which bus operation would return to normal.
6
IBIE
I-Bus Interrupt Enable
0 Interrupts from the IIC bus module are disabled. Note that this does not clear any currently pending interrupt
condition
1 Interrupts from the IIC bus module are enabled. An IIC bus interrupt occurs provided the IBIF bit in the status
register is also set.
5
MS/SL
Master/Slave Mode Select Bit — Upon reset, this bit is cleared. When this bit is changed from 0 to 1, a START
signal is generated on the bus, and the master mode is selected. When this bit is changed from 1 to 0, a STOP
signal is generated and the operation mode changes from master to slave.A STOP signal should only be
generated if the IBIF flag is set. MS/SL is cleared without generating a STOP signal when the master loses
arbitration.
0 Slave Mode
1 Master Mode
4
Tx/Rx
Transmit/Receive Mode Select Bit — This bit selects the direction of master and slave transfers. When
addressed as a slave this bit should be set by software according to the SRW bit in the status register. In master
mode this bit should be set according to the type of transfer required. Therefore, for address cycles, this bit will
always be high.
0 Receive
1 Transmit
3
TXAK
Transmit Acknowledge Enable — This bit specifies the value driven onto SDA during data acknowledge cycles
for both master and slave receivers. The IIC module will always acknowledge address matches, provided it is
enabled, regardless of the value of TXAK. Note that values written to this bit are only used when the IIC bus is a
receiver, not a transmitter.
0 An acknowledge signal will be sent out to the bus at the 9th clock bit after receiving one byte data
1 No acknowledge signal response is sent (i.e., acknowledge bit = 1)
2
RSTA
Repeat Start — Writing a 1 to this bit will generate a repeated START condition on the bus, provided it is the
current bus master. This bit will always be read as a low. Attempting a repeated start at the wrong time, if the bus
is owned by another master, will result in loss of arbitration.
1 Generate repeat start cycle
1
Reserved — Bit 1 of the IBCR is reserved for future compatibility. This bit will always read 0.
RESERVED
0
IBSWAI
I Bus Interface Stop in Wait Mode
0 IIC bus module clock operates normally
1 Halt IIC bus module clock generation in wait mode
Wait mode is entered via execution of a CPU WAI instruction. In the event that the IBSWAI bit is set, all
clocks internal to the IIC will be stopped and any transmission currently in progress will halt.If the CPU
were woken up by a source other than the IIC module, then clocks would restart and the IIC would resume
MC9S12HZ256 Data Sheet, Rev. 2.04
320
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
from where was during the previous transmission. It is not possible for the IIC to wake up the CPU when
its internal clocks are stopped.
If it were the case that the IBSWAI bit was cleared when the WAI instruction was executed, the IIC internal
clocks and interface would remain alive, continuing the operation which was currently underway. It is also
possible to configure the IIC such that it will wake up the CPU via an interrupt at the conclusion of the
current operation. See the discussion on the IBIF and IBIE bits in the IBSR and IBCR, respectively.
11.3.2.4
R
IIC Status Register (IBSR)
7
6
5
TCF
IAAS
IBB
4
3
2
0
SRW
IBAL
1
0
RXAK
IBIF
W
Reset
1
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 11-6. IIC Bus Status Register (IBSR)
This status register is read-only with exception of bit 1 (IBIF) and bit 4 (IBAL), which are software
clearable.
Table 11-8. IBSR Field Descriptions
Field
Description
7
TCF
Data Transferring Bit — While one byte of data is being transferred, this bit is cleared. It is set by the falling
edge of the 9th clock of a byte transfer. Note that this bit is only valid during or immediately following a transfer
to the IIC module or from the IIC module.
0 Transfer in progress
1 Transfer complete
6
IAAS
Addressed as a Slave Bit — When its own specific address (I-bus address register) is matched with the calling
address, this bit is set.The CPU is interrupted provided the IBIE is set.Then the CPU needs to check the SRW
bit and set its Tx/Rx mode accordingly.Writing to the I-bus control register clears this bit.
0 Not addressed
1 Addressed as a slave
5
IBB
Bus Busy Bit
0 This bit indicates the status of the bus. When a START signal is detected, the IBB is set. If a STOP signal is
detected, IBB is cleared and the bus enters idle state.
1 Bus is busy
4
IBAL
Arbitration Lost — The arbitration lost bit (IBAL) is set by hardware when the arbitration procedure is lost.
Arbitration is lost in the following circumstances:
1. SDA sampled low when the master drives a high during an address or data transmit cycle.
2. SDA sampled low when the master drives a high during the acknowledge bit of a data receive cycle.
3. A start cycle is attempted when the bus is busy.
4. A repeated start cycle is requested in slave mode.
5. A stop condition is detected when the master did not request it.
This bit must be cleared by software, by writing a one to it. A write of 0 has no effect on this bit.
3
Reserved — Bit 3 of IBSR is reserved for future use. A read operation on this bit will return 0.
RESERVED
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
321
Chapter 11 Inter-Integrated Circuit (IICV2)
Table 11-8. IBSR Field Descriptions (continued)
Field
Description
2
SRW
Slave Read/Write — When IAAS is set this bit indicates the value of the R/W command bit of the calling address
sent from the master
This bit is only valid when the I-bus is in slave mode, a complete address transfer has occurred with an address
match and no other transfers have been initiated.
Checking this bit, the CPU can select slave transmit/receive mode according to the command of the master.
0 Slave receive, master writing to slave
1 Slave transmit, master reading from slave
1
IBIF
I-Bus Interrupt — The IBIF bit is set when one of the following conditions occurs:
— Arbitration lost (IBAL bit set)
— Byte transfer complete (TCF bit set)
— Addressed as slave (IAAS bit set)
It will cause a processor interrupt request if the IBIE bit is set. This bit must be cleared by software, writing a one
to it. A write of 0 has no effect on this bit.
0
RXAK
Received Acknowledge — The value of SDA during the acknowledge bit of a bus cycle. If the received
acknowledge bit (RXAK) is low, it indicates an acknowledge signal has been received after the completion of 8
bits data transmission on the bus. If RXAK is high, it means no acknowledge signal is detected at the 9th clock.
0 Acknowledge received
1 No acknowledge received
11.3.2.5
IIC Data I/O Register (IBDR)
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 11-7. IIC Bus Data I/O Register (IBDR)
In master transmit mode, when data is written to the IBDR a data transfer is initiated. The most significant
bit is sent first. In master receive mode, reading this register initiates next byte data receiving. In slave
mode, the same functions are available after an address match has occurred.Note that the Tx/Rx bit in the
IBCR must correctly reflect the desired direction of transfer in master and slave modes for the transmission
to begin. For instance, if the IIC is configured for master transmit but a master receive is desired, then
reading the IBDR will not initiate the receive.
Reading the IBDR will return the last byte received while the IIC is configured in either master receive or
slave receive modes. The IBDR does not reflect every byte that is transmitted on the IIC bus, nor can
software verify that a byte has been written to the IBDR correctly by reading it back.
In master transmit mode, the first byte of data written to IBDR following assertion of MS/SL is used for
the address transfer and should com.prise of the calling address (in position D7:D1) concatenated with the
required R/W bit (in position D0).
MC9S12HZ256 Data Sheet, Rev. 2.04
322
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
11.4
Functional Description
This section provides a complete functional description of the IIC.
11.4.1
I-Bus Protocol
The IIC bus system uses a serial data line (SDA) and a serial clock line (SCL) for data transfer. All devices
connected to it must have open drain or open collector outputs. Logic AND function is exercised on both
lines with external pull-up resistors. The value of these resistors is system dependent.
Normally, a standard communication is composed of four parts: START signal, slave address transmission,
data transfer and STOP signal. They are described briefly in the following sections and illustrated in
Figure 11-8.
MSB
SCL
SDA
1
LSB
2
3
4
5
6
7
Calling Address
Read/
Write
MSB
SDA
MSB
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Start
Signal
SCL
8
1
XXX
3
4
5
6
7
8
Calling Address
Read/
Write
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
Data Byte
1
XX
Ack
Bit
9
No Stop
Ack Signal
Bit
MSB
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Start
Signal
2
Ack
Bit
LSB
2
LSB
1
LSB
2
3
4
5
6
7
8
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Repeated
Start
Signal
New Calling Address
Read/
Write
No Stop
Ack Signal
Bit
Figure 11-8. IIC-Bus Transmission Signals
11.4.1.1
START Signal
When the bus is free, i.e. no master device is engaging the bus (both SCL and SDA lines are at logical
high), a master may initiate communication by sending a START signal.As shown in Figure 11-8, a
START signal is defined as a high-to-low transition of SDA while SCL is high. This signal denotes the
beginning of a new data transfer (each data transfer may contain several bytes of data) and brings all slaves
out of their idle states.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
323
Chapter 11 Inter-Integrated Circuit (IICV2)
SDA
SCL
START Condition
STOP Condition
Figure 11-9. Start and Stop Conditions
11.4.1.2
Slave Address Transmission
The first byte of data transfer immediately after the START signal is the slave address transmitted by the
master. This is a seven-bit calling address followed by a R/W bit. The R/W bit tells the slave the desired
direction of data transfer.
1 = Read transfer, the slave transmits data to the master.
0 = Write transfer, the master transmits data to the slave.
Only the slave with a calling address that matches the one transmitted by the master will respond by
sending back an acknowledge bit. This is done by pulling the SDA low at the 9th clock (see Figure 11-8).
No two slaves in the system may have the same address. If the IIC bus is master, it must not transmit an
address that is equal to its own slave address. The IIC bus cannot be master and slave at the same
time.However, if arbitration is lost during an address cycle the IIC bus will revert to slave mode and operate
correctly even if it is being addressed by another master.
11.4.1.3
Data Transfer
As soon as successful slave addressing is achieved, the data transfer can proceed byte-by-byte in a
direction specified by the R/W bit sent by the calling master
All transfers that come after an address cycle are referred to as data transfers, even if they carry sub-address
information for the slave device.
Each data byte is 8 bits long. Data may be changed only while SCL is low and must be held stable while
SCL is high as shown in Figure 11-8. There is one clock pulse on SCL for each data bit, the MSB being
transferred first. Each data byte has to be followed by an acknowledge bit, which is signalled from the
receiving device by pulling the SDA low at the ninth clock. So one complete data byte transfer needs nine
clock pulses.
If the slave receiver does not acknowledge the master, the SDA line must be left high by the slave. The
master can then generate a stop signal to abort the data transfer or a start signal (repeated start) to
commence a new calling.
MC9S12HZ256 Data Sheet, Rev. 2.04
324
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
If the master receiver does not acknowledge the slave transmitter after a byte transmission, it means 'end
of data' to the slave, so the slave releases the SDA line for the master to generate STOP or START signal.
11.4.1.4
STOP Signal
The master can terminate the communication by generating a STOP signal to free the bus. However, the
master may generate a START signal followed by a calling command without generating a STOP signal
first. This is called repeated START. A STOP signal is defined as a low-to-high transition of SDA while
SCL at logical 1 (see Figure 11-8).
The master can generate a STOP even if the slave has generated an acknowledge at which point the slave
must release the bus.
11.4.1.5
Repeated START Signal
As shown in Figure 11-8, a repeated START signal is a START signal generated without first generating a
STOP signal to terminate the communication. This is used by the master to communicate with another
slave or with the same slave in different mode (transmit/receive mode) without releasing the bus.
11.4.1.6
Arbitration Procedure
The Inter-IC bus is a true multi-master bus that allows more than one master to be connected on it. If two
or more masters try to control the bus at the same time, a clock synchronization procedure determines the
bus clock, for which the low period is equal to the longest clock low period and the high is equal to the
shortest one among the masters. The relative priority of the contending masters is determined by a data
arbitration procedure, a bus master loses arbitration if it transmits logic 1 while another master transmits
logic 0. The losing masters immediately switch over to slave receive mode and stop driving SDA output.
In this case the transition from master to slave mode does not generate a STOP condition. Meanwhile, a
status bit is set by hardware to indicate loss of arbitration.
11.4.1.7
Clock Synchronization
Because wire-AND logic is performed on SCL line, a high-to-low transition on SCL line affects all the
devices connected on the bus. The devices start counting their low period and as soon as a device's clock
has gone low, it holds the SCL line low until the clock high state is reached.However, the change of low to
high in this device clock may not change the state of the SCL line if another device clock is within its low
period. Therefore, synchronized clock SCL is held low by the device with the longest low period. Devices
with shorter low periods enter a high wait state during this time (see Figure 11-9). When all devices
concerned have counted off their low period, the synchronized clock SCL line is released and pulled high.
There is then no difference between the device clocks and the state of the SCL line and all the devices start
counting their high periods.The first device to complete its high period pulls the SCL line low again.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
325
Chapter 11 Inter-Integrated Circuit (IICV2)
WAIT
Start Counting High Period
SCL1
SCL2
SCL
Internal Counter Reset
Figure 11-10. IIC-Bus Clock Synchronization
11.4.1.8
Handshaking
The clock synchronization mechanism can be used as a handshake in data transfer. Slave devices may hold
the SCL low after completion of one byte transfer (9 bits). In such case, it halts the bus clock and forces
the master clock into wait states until the slave releases the SCL line.
11.4.1.9
Clock Stretching
The clock synchronization mechanism can be used by slaves to slow down the bit rate of a transfer. After
the master has driven SCL low the slave can drive SCL low for the required period and then release it.If
the slave SCL low period is greater than the master SCL low period then the resulting SCL bus signal low
period is stretched.
11.4.2
Operation in Run Mode
This is the basic mode of operation.
11.4.3
Operation in Wait Mode
IIC operation in wait mode can be configured. Depending on the state of internal bits, the IIC can operate
normally when the CPU is in wait mode or the IIC clock generation can be turned off and the IIC module
enters a power conservation state during wait mode. In the later case, any transmission or reception in
progress stops at wait mode entry.
11.4.4
Operation in Stop Mode
The IIC is inactive in stop mode for reduced power consumption. The STOP instruction does not affect IIC
register states.
MC9S12HZ256 Data Sheet, Rev. 2.04
326
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
11.5
Resets
The reset state of each individual bit is listed in Section 11.3, “Memory Map and Register Definition,”
which details the registers and their bit-fields.
11.6
Interrupts
IIC uses only one interrupt vector.
Table 11-9. Interrupt Summary
Interrupt
Offset
Vector
Priority
IIC
Interrupt
—
—
—
Source
Description
IBAL, TCF, IAAS When either of IBAL, TCF or IAAS bits is set
bits in IBSR
may cause an interrupt based on arbitration
register
lost, transfer complete or address detect
conditions
Internally there are three types of interrupts in IIC. The interrupt service routine can determine the interrupt
type by reading the status register.
IIC Interrupt can be generated on
1. Arbitration lost condition (IBAL bit set)
2. Byte transfer condition (TCF bit set)
3. Address detect condition (IAAS bit set)
The IIC interrupt is enabled by the IBIE bit in the IIC control register. It must be cleared by writing 0 to
the IBF bit in the interrupt service routine.
11.7
Initialization/Application Information
11.7.1
11.7.1.1
IIC Programming Examples
Initialization Sequence
Reset will put the IIC bus control register to its default status. Before the interface can be used to transfer
serial data, an initialization procedure must be carried out, as follows:
1. Update the frequency divider register (IBFD) and select the required division ratio to obtain SCL
frequency from system clock.
2. Update the IIC bus address register (IBAD) to define its slave address.
3. Set the IBEN bit of the IIC bus control register (IBCR) to enable the IIC interface system.
4. Modify the bits of the IIC bus control register (IBCR) to select master/slave mode, transmit/receive
mode and interrupt enable or not.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
327
Chapter 11 Inter-Integrated Circuit (IICV2)
11.7.1.2
Generation of START
After completion of the initialization procedure, serial data can be transmitted by selecting the 'master
transmitter' mode. If the device is connected to a multi-master bus system, the state of the IIC bus busy bit
(IBB) must be tested to check whether the serial bus is free.
If the bus is free (IBB=0), the start condition and the first byte (the slave address) can be sent. The data
written to the data register comprises the slave calling address and the LSB set to indicate the direction of
transfer required from the slave.
The bus free time (i.e., the time between a STOP condition and the following START condition) is built
into the hardware that generates the START cycle. Depending on the relative frequencies of the system
clock and the SCL period it may be necessary to wait until the IIC is busy after writing the calling address
to the IBDR before proceeding with the following instructions. This is illustrated in the following example.
An example of a program which generates the START signal and transmits the first byte of data (slave
address) is shown below:
CHFLAG
BRSET
IBSR,#$20,*
;WAIT FOR IBB FLAG TO CLEAR
TXSTART
BSET
IBCR,#$30
;SET TRANSMIT AND MASTER MODE;i.e. GENERATE START CONDITION
MOVB
CALLING,IBDR
;TRANSMIT THE CALLING ADDRESS, D0=R/W
BRCLR
IBSR,#$20,*
;WAIT FOR IBB FLAG TO SET
IBFREE
11.7.1.3
Post-Transfer Software Response
Transmission or reception of a byte will set the data transferring bit (TCF) to 1, which indicates one byte
communication is finished. The IIC bus interrupt bit (IBIF) is set also; an interrupt will be generated if the
interrupt function is enabled during initialization by setting the IBIE bit. Software must clear the IBIF bit
in the interrupt routine first. The TCF bit will be cleared by reading from the IIC bus data I/O register
(IBDR) in receive mode or writing to IBDR in transmit mode.
Software may service the IIC I/O in the main program by monitoring the IBIF bit if the interrupt function
is disabled. Note that polling should monitor the IBIF bit rather than the TCF bit because their operation
is different when arbitration is lost.
Note that when an interrupt occurs at the end of the address cycle the master will always be in transmit
mode, i.e. the address is transmitted. If master receive mode is required, indicated by R/W bit in IBDR,
then the Tx/Rx bit should be toggled at this stage.
During slave mode address cycles (IAAS=1), the SRW bit in the status register is read to determine the
direction of the subsequent transfer and the Tx/Rx bit is programmed accordingly. For slave mode data
cycles (IAAS=0) the SRW bit is not valid, the Tx/Rx bit in the control register should be read to determine
the direction of the current transfer.
The following is an example of a software response by a 'master transmitter' in the interrupt routine.
ISR
TRANSMIT
BCLR
BRCLR
BRCLR
BRSET
MOVB
IBSR,#$02
IBCR,#$20,SLAVE
IBCR,#$10,RECEIVE
IBSR,#$01,END
DATABUF,IBDR
;CLEAR THE IBIF FLAG
;BRANCH IF IN SLAVE MODE
;BRANCH IF IN RECEIVE MODE
;IF NO ACK, END OF TRANSMISSION
;TRANSMIT NEXT BYTE OF DATA
MC9S12HZ256 Data Sheet, Rev. 2.04
328
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
11.7.1.4
Generation of STOP
A data transfer ends with a STOP signal generated by the 'master' device. A master transmitter can simply
generate a STOP signal after all the data has been transmitted. The following is an example showing how
a stop condition is generated by a master transmitter.
MASTX
END
EMASTX
TST
BEQ
BRSET
MOVB
DEC
BRA
BCLR
RTI
TXCNT
END
IBSR,#$01,END
DATABUF,IBDR
TXCNT
EMASTX
IBCR,#$20
;GET VALUE FROM THE TRANSMITING COUNTER
;END IF NO MORE DATA
;END IF NO ACK
;TRANSMIT NEXT BYTE OF DATA
;DECREASE THE TXCNT
;EXIT
;GENERATE A STOP CONDITION
;RETURN FROM INTERRUPT
If a master receiver wants to terminate a data transfer, it must inform the slave transmitter by not
acknowledging the last byte of data which can be done by setting the transmit acknowledge bit (TXAK)
before reading the 2nd last byte of data. Before reading the last byte of data, a STOP signal must be
generated first. The following is an example showing how a STOP signal is generated by a master receiver.
MASR
DEC
BEQ
MOVB
DEC
BNE
BSET
RXCNT
ENMASR
RXCNT,D1
D1
NXMAR
IBCR,#$08
ENMASR
NXMAR
BRA
BCLR
MOVB
RTI
NXMAR
IBCR,#$20
IBDR,RXBUF
11.7.1.5
Generation of Repeated START
LAMAR
;DECREASE THE RXCNT
;LAST BYTE TO BE READ
;CHECK SECOND LAST BYTE
;TO BE READ
;NOT LAST OR SECOND LAST
;SECOND LAST, DISABLE ACK
;TRANSMITTING
;LAST ONE, GENERATE ‘STOP’ SIGNAL
;READ DATA AND STORE
At the end of data transfer, if the master continues to want to communicate on the bus, it can generate
another START signal followed by another slave address without first generating a STOP signal. A
program example is as shown.
RESTART
BSET
MOVB
IBCR,#$04
CALLING,IBDR
11.7.1.6
Slave Mode
;ANOTHER START (RESTART)
;TRANSMIT THE CALLING ADDRESS;D0=R/W
In the slave interrupt service routine, the module addressed as slave bit (IAAS) should be tested to check
if a calling of its own address has just been received. If IAAS is set, software should set the transmit/receive
mode select bit (Tx/Rx bit of IBCR) according to the R/W command bit (SRW). Writing to the IBCR
clears the IAAS automatically. Note that the only time IAAS is read as set is from the interrupt at the end
of the address cycle where an address match occurred, interrupts resulting from subsequent data transfers
will have IAAS cleared. A data transfer may now be initiated by writing information to IBDR, for slave
transmits, or dummy reading from IBDR, in slave receive mode. The slave will drive SCL low in-between
byte transfers, SCL is released when the IBDR is accessed in the required mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
329
Chapter 11 Inter-Integrated Circuit (IICV2)
In slave transmitter routine, the received acknowledge bit (RXAK) must be tested before transmitting the
next byte of data. Setting RXAK means an 'end of data' signal from the master receiver, after which it must
be switched from transmitter mode to receiver mode by software. A dummy read then releases the SCL
line so that the master can generate a STOP signal.
11.7.1.7
Arbitration Lost
If several masters try to engage the bus simultaneously, only one master wins and the others lose
arbitration. The devices which lost arbitration are immediately switched to slave receive mode by the
hardware. Their data output to the SDA line is stopped, but SCL continues to be generated until the end of
the byte during which arbitration was lost. An interrupt occurs at the falling edge of the ninth clock of this
transfer with IBAL=1 and MS/SL=0. If one master attempts to start transmission while the bus is being
engaged by another master, the hardware will inhibit the transmission; switch the MS/SL bit from 1 to 0
without generating STOP condition; generate an interrupt to CPU and set the IBAL to indicate that the
attempt to engage the bus is failed. When considering these cases, the slave service routine should test the
IBAL first and the software should clear the IBAL bit if it is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
330
Freescale Semiconductor
Chapter 11 Inter-Integrated Circuit (IICV2)
Clear
IBIF
Master
Mode
?
Y
TX
N
Arbitration
Lost
?
Y
RX
Tx/Rx
?
N
Last Byte
Transmitted
?
N
Clear IBAL
Y
RXAK=0
?
Last
Byte To Be Read
?
N
N
Y
N
Y
Y
IAAS=1
?
IAAS=1
?
Y
N
Address Transfer
End Of
Addr Cycle
(Master Rx)
?
N
Y
Y
Y
(Read)
2nd Last
Byte To Be Read
?
SRW=1
?
Write Next
Byte To IBDR
Generate
Stop Signal
Set TXAK =1
Generate
Stop Signal
Read Data
From IBDR
And Store
ACK From
Receiver
?
N
Read Data
From IBDR
And Store
Tx Next
Byte
Set RX
Mode
Switch To
Rx Mode
Dummy Read
From IBDR
Dummy Read
From IBDR
Switch To
Rx Mode
RX
TX
Y
Set TX
Mode
Write Data
To IBDR
Dummy Read
From IBDR
TX/RX
?
N (Write)
N
Data Transfer
RTI
Figure 11-11. Flow-Chart of Typical IIC Interrupt Routine
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
331
Chapter 11 Inter-Integrated Circuit (IICV2)
MC9S12HZ256 Data Sheet, Rev. 2.04
332
Freescale Semiconductor
Chapter 12
Freescale’s Scalable Controller Area Network (MSCANV2)
12.1
Introduction
Freescale’s scalable controller area network (MSCAN) definition is based on the MSCAN12 definition,
which is the specific implementation of the MSCAN concept targeted for the M68HC12 microcontroller
family.
The module is a communication controller implementing the CAN 2.0A/B protocol as defined in the
Bosch specification dated September 1991. For users to fully understand the MSCAN specification, it is
recommended that the Bosch specification be read first to familiarize the reader with the terms and
concepts contained within this document.
Though not exclusively intended for automotive applications, CAN protocol is designed to meet the
specific requirements of a vehicle serial data bus: real-time processing, reliable operation in the EMI
environment of a vehicle, cost-effectiveness, and required bandwidth.
MSCAN uses an advanced buffer arrangement resulting in predictable real-time behavior and simplified
application software.
12.1.1
Block Diagram
MSCAN
Oscillator Clock
Bus Clock
CANCLK
MUX
Presc.
Tq Clk
Receive/
Transmit
Engine
RXCAN
TXCAN
Transmit Interrupt Req.
Receive Interrupt Req.
Errors Interrupt Req.
Message
Filtering
and
Buffering
Control
and
Status
Wake-Up Interrupt Req.
Configuration
Registers
Wake-Up
Low Pass Filter
Figure 12-1. MSCAN Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
333
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.1.2
Features
The basic features of the MSCAN are as follows:
• Implementation of the CAN protocol — Version 2.0A/B
— Standard and extended data frames
— Zero to eight bytes data length
— Programmable bit rate up to 1 Mbps1
— Support for remote frames
• Five receive buffers with FIFO storage scheme
• Three transmit buffers with internal prioritization using a “local priority” concept
• Flexible maskable identifier filter supports two full-size (32-bit) extended identifier filters, or four
16-bit filters, or eight 8-bit filters
• Programmable wakeup functionality with integrated low-pass filter
• Programmable loopback mode supports self-test operation
• Programmable listen-only mode for monitoring of CAN bus
• Separate signalling and interrupt capabilities for all CAN receiver and transmitter error states
(warning, error passive, bus-off)
• Programmable MSCAN clock source either bus clock or oscillator clock
• Internal timer for time-stamping of received and transmitted messages
• Three low-power modes: sleep, power down, and MSCAN enable
• Global initialization of configuration registers
12.1.3
Modes of Operation
The following modes of operation are specific to the MSCAN. See Section 12.4, “Functional Description,”
for details.
• Listen-Only Mode
• MSCAN Sleep Mode
• MSCAN Initialization Mode
• MSCAN Power Down Mode
12.2
External Signal Description
The MSCAN uses two external pins:
12.2.1
RXCAN — CAN Receiver Input Pin
RXCAN is the MSCAN receiver input pin.
1. Depending on the actual bit timing and the clock jitter of the PLL.
MC9S12HZ256 Data Sheet, Rev. 2.04
334
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.2.2
TXCAN — CAN Transmitter Output Pin
TXCAN is the MSCAN transmitter output pin. The TXCAN output pin represents the logic level on the
CAN bus:
0 = Dominant state
1 = Recessive state
12.2.3
CAN System
A typical CAN system with MSCAN is shown in Figure 12-2. Each CAN station is connected physically
to the CAN bus lines through a transceiver device. The transceiver is capable of driving the large current
needed for the CAN bus and has current protection against defective CAN or defective stations.
CAN node 2
CAN node 1
CAN node n
MCU
CAN Controller
(MSCAN)
TXCAN
RXCAN
Transceiver
CAN_H
CAN_L
CAN Bus
Figure 12-2. CAN System
12.3
Memory Map and Register Definition
This section provides a detailed description of all registers accessible in the MSCAN.
12.3.1
Module Memory Map
Table 12-1 gives an overview on all registers and their individual bits in the MSCAN memory map. The
register address results from the addition of base address and address offset. The base address is
determined at the MCU level and can be found in the Memory block description chapter. The address offset
is defined at the module level.
The MSCAN occupies 64 bytes in the memory space. The base address of the MSCAN module is
determined at the MCU level when the MCU is defined. The register decode map is fixed and begins at the
first address of the module address offset.
Table 12-1 shows the individual registers associated with the MSCAN and their relative offset from the
base address. The detailed register descriptions follow in the order they appear in the register map.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
335
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-1. MSCAN Memory Map
Address
Offset
1
2
Register
Access
0x0000
MSCAN Control Register 0 (CANCTL0)
R/W1
0x0001
MSCAN Control Register 1 (CANCTL1)
R/W1
0x0002
MSCAN Bus Timing Register 0 (CANBTR0)
R/W
0x0003
MSCAN Bus Timing Register 1 (CANBTR1)
R/W
0x0004
MSCAN Receiver Flag Register (CANRFLG)
R/W1
0x0005
MSCAN Receiver Interrupt Enable Register (CANRIER)
R/W
0x0006
MSCAN Transmitter Flag Register (CANTFLG)
R/W1
0x0007
MSCAN Transmitter Interrupt Enable Register (CANTIER)
R/W1
0x0008
MSCAN Transmitter Message Abort Request Register (CANTARQ)
R/W1
0x0009
MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
0x000A
MSCAN Transmit Buffer Selection Register (CANTBSEL)
R/W1
R
0x000B
MSCAN Identifier Acceptance Control Register (CANIDAC)
R/W1
0x000C
RESERVED
0x000D
RESERVED
0x000E
MSCAN Receive Error Counter (CANRXERR)
0x000F
MSCAN Transmit Error Counter (CANTXERR)
0x0010
MSCAN Identifier Acceptance Register 0(CANIDAR0)
R/W
0x0011
MSCAN Identifier Acceptance Register 1(CANIDAR1)
R/W
0x0012
MSCAN Identifier Acceptance Register 2 (CANIDAR2)
R/W
0x0013
MSCAN Identifier Acceptance Register 3 (CANIDAR3)
R/W
0x0014
MSCAN Identifier Mask Register 0 (CANIDMR0)
R/W
0x0015
MSCAN Identifier Mask Register 1 (CANIDMR1)
R/W
0x0016
MSCAN Identifier Mask Register 2 (CANIDMR2)
R/W
0x0017
MSCAN Identifier Mask Register 3 (CANIDMR3)
R/W
0x0018
MSCAN Identifier Acceptance Register 4 (CANIDAR4)
R/W
0x0019
MSCAN Identifier Acceptance Register 5 (CANIDAR5)
R/W
0x001A
MSCAN Identifier Acceptance Register 6 (CANIDAR6)
R/W
R
R
0x001B
MSCAN Identifier Acceptance Register 7 (CANIDAR7)
R/W
0x001C
MSCAN Identifier Mask Register 4 (CANIDMR4)
R/W
0x001D
MSCAN Identifier Mask Register 5 (CANIDMR5)
R/W
0x001E
MSCAN Identifier Mask Register 6 (CANIDMR6)
R/W
0x001F
MSCAN Identifier Mask Register 7 (CANIDMR7)
R/W
0x0020
-0x002F
Foreground Receive Buffer (CANRXFG)
R2
0x0030
-0x003F
Foreground Transmit Buffer (CANTXFG)
R2/W
Refer to detailed register description for write access restrictions on per bit basis.
Reserved bits and unused bits within the TX- and RX-buffers (CANTXFG, CANRXFG) will be read
as “X”, because of RAM-based implementation.
MC9S12HZ256 Data Sheet, Rev. 2.04
336
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-2. MSCAN Memory Map
Offset
Address
1
Register
Access
0x0000
This section describes in detail all the registers and register bits in the
MSCAN module. Each description includes a standard register diagram
with an associated figure number. Details of register bit and field
function follow the register diagrams, in bit order. All bits of all registers
in this module are completely synchronous to internal clocks during a
register read.
R/W1
0x0001
MSCAN Control Register 1 (CANCTL1)
R/W1
0x0002
MSCAN Bus Timing Register 0 (CANBTR0)
R/W
0x0003
MSCAN Bus Timing Register 1 (CANBTR1)
R/W
0x0004
MSCAN Receiver Flag Register (CANRFLG)
R/W1
0x0005
MSCAN Receiver Interrupt Enable Register (CANRIER)
R/W
0x0006
MSCAN Transmitter Flag Register (CANTFLG)
R/W1
0x0007
MSCAN Transmitter Interrupt Enable Register (CANTIER)
R/W1
0x0008
MSCAN Transmitter Message Abort Request Register (CANTARQ)
R/W1
0x0009
MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
0x000A
MSCAN Transmit Buffer Selection Register (CANTBSEL)
R/W1
0x000B
MSCAN Identifier Acceptance Control Register (CANIDAC)
R/W1
0x000C
RESERVED
0x000D
RESERVED
R
0x000E
MSCAN Receive Error Counter (CANRXERR)
R
0x000F
MSCAN Transmit Error Counter (CANTXERR)
R
0x0010
MSCAN Identifier Acceptance Register 0(CANIDAR0)
R/W
0x0011
MSCAN Identifier Acceptance Register 1(CANIDAR1)
R/W
0x0012
MSCAN Identifier Acceptance Register 2 (CANIDAR2)
R/W
0x0013
MSCAN Identifier Acceptance Register 3 (CANIDAR3)
R/W
0x0014
MSCAN Identifier Mask Register 0 (CANIDMR0)
R/W
0x0015
MSCAN Identifier Mask Register 1 (CANIDMR1)
R/W
0x0016
MSCAN Identifier Mask Register 2 (CANIDMR2)
R/W
0x0017
MSCAN Identifier Mask Register 3 (CANIDMR3)
R/W
0x0018
MSCAN Identifier Acceptance Register 4 (CANIDAR4)
R/W
0x0019
MSCAN Identifier Acceptance Register 5 (CANIDAR5)
R/W
0x001A
MSCAN Identifier Acceptance Register 6 (CANIDAR6)
R/W
0x001B
MSCAN Identifier Acceptance Register 7 (CANIDAR7)
R/W
0x001C
MSCAN Identifier Mask Register 4 (CANIDMR4)
R/W
0x001D
MSCAN Identifier Mask Register 5 (CANIDMR5)
R/W
0x001E
MSCAN Identifier Mask Register 6 (CANIDMR6)
R/W
0x001F
MSCAN Identifier Mask Register 7 (CANIDMR7)
R/W
0x0020
-0x002F
Foreground Receive Buffer (CANRXFG)
R2
0x0030
-0x003F
Foreground Transmit Buffer (CANTXFG)
R2/W
Refer to detailed register description for write access restrictions on per bit basis.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
337
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
2
12.3.2
Reserved bits and unused bits within the TX- and RX-buffers (CANTXFG, CANRXFG) will be read
as “x”, because of RAM-based implementation.
Register Descriptions
This section describes in detail all the registers and register bits in the MSCAN module. Each description
includes a standard register diagram with an associated figure number. Details of register bit and field
function follow the register diagrams, in bit order. All bits of all registers in this module are completely
synchronous to internal clocks during a register read.
12.3.2.1
MSCAN Control Register 0 (CANCTL0)
The CANCTL0 register provides various control bits of the MSCAN module as described below.
7
R
6
5
RXACT
RXFRM
4
3
2
1
0
TIME
WUPE
SLPRQ
INITRQ
0
0
0
1
SYNCH
CSWAI
W
Reset:
0
0
0
0
= Unimplemented
Figure 12-3. MSCAN Control Register 0 (CANCTL0)
NOTE
The CANCTL0 register, except WUPE, INITRQ, and SLPRQ, is held in the
reset state when the initialization mode is active (INITRQ = 1 and
INITAK = 1). This register is writable again as soon as the initialization
mode is exited (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime when out of initialization mode; exceptions are read-only RXACT and SYNCH, RXFRM
(which is set by the module only), and INITRQ (which is also writable in initialization mode).
Table 12-3. CANCTL0 Register Field Descriptions
Field
Description
7
RXFRM1
Received Frame Flag — This bit is read and clear only. It is set when a receiver has received a valid message
correctly, independently of the filter configuration. After it is set, it remains set until cleared by software or reset.
Clearing is done by writing a 1. Writing a 0 is ignored. This bit is not valid in loopback mode.
0 No valid message was received since last clearing this flag
1 A valid message was received since last clearing of this flag
6
RXACT
Receiver Active Status — This read-only flag indicates the MSCAN is receiving a message. The flag is
controlled by the receiver front end. This bit is not valid in loopback mode.
0 MSCAN is transmitting or idle2
1 MSCAN is receiving a message (including when arbitration is lost)2
5
CSWAI3
CAN Stops in Wait Mode — Enabling this bit allows for lower power consumption in wait mode by disabling all
the clocks at the CPU bus interface to the MSCAN module.
0 The module is not affected during wait mode
1 The module ceases to be clocked during wait mode
MC9S12HZ256 Data Sheet, Rev. 2.04
338
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-3. CANCTL0 Register Field Descriptions (continued)
1
2
3
4
5
6
7
Field
Description
4
SYNCH
Synchronized Status — This read-only flag indicates whether the MSCAN is synchronized to the CAN bus and
able to participate in the communication process. It is set and cleared by the MSCAN.
0 MSCAN is not synchronized to the CAN bus
1 MSCAN is synchronized to the CAN bus
3
TIME
Timer Enable — This bit activates an internal 16-bit wide free running timer which is clocked by the bit clock rate.
If the timer is enabled, a 16-bit time stamp will be assigned to each transmitted/received message within the
active TX/RX buffer. As soon as a message is acknowledged on the CAN bus, the time stamp will be written to
the highest bytes (0x000E, 0x000F) in the appropriate buffer (see Section 12.3.3, “Programmer’s Model of
Message Storage”). The internal timer is reset (all bits set to 0) when disabled. This bit is held low in initialization
mode.
0 Disable internal MSCAN timer
1 Enable internal MSCAN timer
2
WUPE4
Wake-Up Enable — This configuration bit allows the MSCAN to restart from sleep mode when traffic on CAN is
detected (see Section 12.4.6.4, “MSCAN Sleep Mode”).
0 Wake-up disabled — The MSCAN ignores traffic on CAN
1 Wake-up enabled — The MSCAN is able to restart
1
SLPRQ5
Sleep Mode Request — This bit requests the MSCAN to enter sleep mode, which is an internal power saving
mode (see Section 12.4.6.4, “MSCAN Sleep Mode”). The sleep mode request is serviced when the CAN bus is
idle, i.e., the module is not receiving a message and all transmit buffers are empty. The module indicates entry
to sleep mode by setting SLPAK = 1 (see Section 12.3.2.2, “MSCAN Control Register 1 (CANCTL1)”). Sleep
mode will be active until SLPRQ is cleared by the CPU or, depending on the setting of WUPE, the MSCAN
detects activity on the CAN bus and clears SLPRQ itself.
0 Running — The MSCAN functions normally
1 Sleep mode request — The MSCAN enters sleep mode when CAN bus idle
0
INITRQ6,7
Initialization Mode Request — When this bit is set by the CPU, the MSCAN skips to initialization mode (see
Section 12.4.6.5, “MSCAN Initialization Mode”). Any ongoing transmission or reception is aborted and
synchronization to the CAN bus is lost. The module indicates entry to initialization mode by setting INITAK = 1
(Section 12.3.2.2, “MSCAN Control Register 1 (CANCTL1)”).
The following registers enter their hard reset state and restore their default values: CANCTL08, CANRFLG9,
CANRIER10, CANTFLG, CANTIER, CANTARQ, CANTAAK, and CANTBSEL.
The registers CANCTL1, CANBTR0, CANBTR1, CANIDAC, CANIDAR0-7, and CANIDMR0-7 can only be
written by the CPU when the MSCAN is in initialization mode (INITRQ = 1 and INITAK = 1). The values of the
error counters are not affected by initialization mode.
When this bit is cleared by the CPU, the MSCAN restarts and then tries to synchronize to the CAN bus. If the
MSCAN is not in bus-off state, it synchronizes after 11 consecutive recessive bits on the CAN bus; if the MSCAN
is in bus-off state, it continues to wait for 128 occurrences of 11 consecutive recessive bits.
Writing to other bits in CANCTL0, CANRFLG, CANRIER, CANTFLG, or CANTIER must be done only after
initialization mode is exited, which is INITRQ = 0 and INITAK = 0.
0 Normal operation
1 MSCAN in initialization mode
The MSCAN must be in normal mode for this bit to become set.
See the Bosch CAN 2.0A/B specification for a detailed definition of transmitter and receiver states.
In order to protect from accidentally violating the CAN protocol, the TXCAN pin is immediately forced to a recessive state when
the CPU enters wait (CSWAI = 1) or stop mode (see Section 12.4.6.2, “Operation in Wait Mode” and Section 12.4.6.3,
“Operation in Stop Mode”).
The CPU has to make sure that the WUPE register and the WUPIE wake-up interrupt enable register (see Section 12.3.2.6,
“MSCAN Receiver Interrupt Enable Register (CANRIER)) is enabled, if the recovery mechanism from stop or wait is required.
The CPU cannot clear SLPRQ before the MSCAN has entered sleep mode (SLPRQ = 1 and SLPAK = 1).
The CPU cannot clear INITRQ before the MSCAN has entered initialization mode (INITRQ = 1 and INITAK = 1).
In order to protect from accidentally violating the CAN protocol, the TXCAN pin is immediately forced to a recessive state when
the initialization mode is requested by the CPU. Thus, the recommended procedure is to bring the MSCAN into sleep mode
(SLPRQ = 1 and SLPAK = 1) before requesting initialization mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
339
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
8
Not including WUPE, INITRQ, and SLPRQ.
TSTAT1 and TSTAT0 are not affected by initialization mode.
10
RSTAT1 and RSTAT0 are not affected by initialization mode.
9
12.3.2.2
MSCAN Control Register 1 (CANCTL1)
The CANCTL1 register provides various control bits and handshake status information of the MSCAN
module as described below.
Read: Anytime
Write: Anytime when INITRQ = 1 and INITAK = 1, except CANE which is write once in normal and
anytime in special system operation modes when the MSCAN is in initialization mode (INITRQ = 1 and
INITAK = 1).
Table 12-4. CANCTL1 Register Field Descriptions
Field
7
CANE
Description
MSCAN Enable
0 MSCAN module is disabled
1 MSCAN module is enabled
6
CLKSRC
MSCAN Clock Source — This bit defines the clock source for the MSCAN module (only for systems with a clock
generation module; Section 12.4.3.2, “Clock System,” and Section Figure 12-40., “MSCAN Clocking Scheme,”).
0 MSCAN clock source is the oscillator clock
1 MSCAN clock source is the bus clock
5
LOOPB
Loopback Self Test Mode — When this bit is set, the MSCAN performs an internal loopback which can be used
for self test operation. The bit stream output of the transmitter is fed back to the receiver internally. The RXCAN
input pin is ignored and the TXCAN output goes to the recessive state (logic 1). The MSCAN behaves as it does
normally when transmitting and treats its own transmitted message as a message received from a remote node.
In this state, the MSCAN ignores the bit sent during the ACK slot in the CAN frame acknowledge field to ensure
proper reception of its own message. Both transmit and receive interrupts are generated.
0 Loopback self test disabled
1 Loopback self test enabled
4
LISTEN
Listen Only Mode — This bit configures the MSCAN as a CAN bus monitor. When LISTEN is set, all valid CAN
messages with matching ID are received, but no acknowledgement or error frames are sent out (see
Section 12.4.5.4, “Listen-Only Mode”). In addition, the error counters are frozen. Listen only mode supports
applications which require “hot plugging” or throughput analysis. The MSCAN is unable to transmit any
messages when listen only mode is active.
0 Normal operation
1 Listen only mode activated
2
WUPM
Wake-Up Mode — If WUPE in CANCTL0 is enabled, this bit defines whether the integrated low-pass filter is
applied to protect the MSCAN from spurious wake-up (see Section 12.4.6.4, “MSCAN Sleep Mode”).
0 MSCAN wakes up the CPU after any recessive to dominant edge on the CAN bus
1 MSCAN wakes up the CPU only in case of a dominant pulse on the CAN bus that has a length of Twup
MC9S12HZ256 Data Sheet, Rev. 2.04
340
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-4. CANCTL1 Register Field Descriptions (continued)
Field
Description
1
SLPAK
Sleep Mode Acknowledge — This flag indicates whether the MSCAN module has entered sleep mode (see
Section 12.4.6.4, “MSCAN Sleep Mode”). It is used as a handshake flag for the SLPRQ sleep mode request.
Sleep mode is active when SLPRQ = 1 and SLPAK = 1. Depending on the setting of WUPE, the MSCAN will
clear the flag if it detects activity on the CAN bus while in sleep mode.
0 Running — The MSCAN operates normally
1 Sleep mode active — The MSCAN has entered sleep mode
0
INITAK
Initialization Mode Acknowledge — This flag indicates whether the MSCAN module is in initialization mode
(see Section 12.4.6.5, “MSCAN Initialization Mode”). It is used as a handshake flag for the INITRQ initialization
mode request. Initialization mode is active when INITRQ = 1 and INITAK = 1. The registers CANCTL1,
CANBTR0, CANBTR1, CANIDAC, CANIDAR0–CANIDAR7, and CANIDMR0–CANIDMR7 can be written only by
the CPU when the MSCAN is in initialization mode.
0 Running — The MSCAN operates normally
1 Initialization mode active — The MSCAN has entered initialization mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
341
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.3
MSCAN Bus Timing Register 0 (CANBTR0)
The CANBTR0 register configures various CAN bus timing parameters of the MSCAN module.
7
6
5
4
3
2
1
0
SJW1
SJW0
BRP5
BRP4
BRP3
BRP2
BRP1
BRP0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 12-4. MSCAN Bus Timing Register 0 (CANBTR0)
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
Table 12-5. CANBTR0 Register Field Descriptions
Field
Description
7:6
SJW[1:0]
Synchronization Jump Width — The synchronization jump width defines the maximum number of time quanta
(Tq) clock cycles a bit can be shortened or lengthened to achieve resynchronization to data transitions on the
CAN bus (see Table 12-6).
5:0
BRP[5:0]
Baud Rate Prescaler — These bits determine the time quanta (Tq) clock which is used to build up the bit timing
(see Table 12-7).
Table 12-6. Synchronization Jump Width
SJW1
SJW0
Synchronization Jump Width
0
0
1 Tq clock cycle
0
1
2 Tq clock cycles
1
0
3 Tq clock cycles
1
1
4 Tq clock cycles
Table 12-7. Baud Rate Prescaler
BRP5
BRP4
BRP3
BRP2
BRP1
BRP0
Prescaler value (P)
0
0
0
0
0
0
1
0
0
0
0
0
1
2
0
0
0
0
1
0
3
0
0
0
0
1
1
4
:
:
:
:
:
:
:
1
1
1
1
1
1
64
MC9S12HZ256 Data Sheet, Rev. 2.04
342
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.4
MSCAN Bus Timing Register 1 (CANBTR1)
The CANBTR1 register configures various CAN bus timing parameters of the MSCAN module.
7
6
5
4
3
2
1
0
SAMP
TSEG22
TSEG21
TSEG20
TSEG13
TSEG12
TSEG11
TSEG10
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 12-5. MSCAN Bus Timing Register 1 (CANBTR1)
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
Table 12-8. CANBTR1 Register Field Descriptions
Field
Description
7
SAMP
Sampling — This bit determines the number of CAN bus samples taken per bit time.
0 One sample per bit.
1 Three samples per bit1.
If SAMP = 0, the resulting bit value is equal to the value of the single bit positioned at the sample point. If
SAMP = 1, the resulting bit value is determined by using majority rule on the three total samples. For higher bit
rates, it is recommended that only one sample is taken per bit time (SAMP = 0).
6:4
Time Segment 2 — Time segments within the bit time fix the number of clock cycles per bit time and the location
TSEG2[2:0] of the sample point (see Figure 12-41). Time segment 2 (TSEG2) values are programmable as shown in
Table 12-9.
3:0
Time Segment 1 — Time segments within the bit time fix the number of clock cycles per bit time and the location
TSEG1[3:0] of the sample point (see Figure 12-41). Time segment 1 (TSEG1) values are programmable as shown in
Table 12-10.
1
In this case, PHASE_SEG1 must be at least 2 time quanta (Tq).
Table 12-9. Time Segment 2 Values
1
TSEG22
TSEG21
TSEG20
Time Segment 2
0
0
0
1 Tq clock cycle1
0
0
1
2 Tq clock cycles
:
:
:
:
1
1
0
7 Tq clock cycles
1
1
1
8 Tq clock cycles
This setting is not valid. Please refer to Table 12-36 for valid settings.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
343
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-10. Time Segment 1 Values
1
TSEG13
TSEG12
TSEG11
TSEG10
Time segment 1
0
0
0
0
1 Tq clock cycle1
0
0
0
1
2 Tq clock cycles1
0
0
1
0
3 Tq clock cycles1
0
0
1
1
4 Tq clock cycles
:
:
:
:
:
1
1
1
0
15 Tq clock cycles
1
1
1
1
16 Tq clock cycles
This setting is not valid. Please refer to Table 12-36 for valid settings.
The bit time is determined by the oscillator frequency, the baud rate prescaler, and the number of time
quanta (Tq) clock cycles per bit (as shown in Table 12-9 and Table 12-10).
Eqn. 12-1
( Prescaler value )
Bit Time = ------------------------------------------------------ • ( 1 + TimeSegment1 + TimeSegment2 )
f CANCLK
12.3.2.5
MSCAN Receiver Flag Register (CANRFLG)
A flag can be cleared only by software (writing a 1 to the corresponding bit position) when the condition
which caused the setting is no longer valid. Every flag has an associated interrupt enable bit in the
CANRIER register.
7
6
R
WUPIF
CSCIF
0
0
5
4
3
2
RSTAT1
RSTAT0
TSTAT1
TSTAT0
1
0
OVRIF
RXF
0
0
W
Reset:
0
0
0
0
= Unimplemented
Figure 12-6. MSCAN Receiver Flag Register (CANRFLG)
NOTE
The CANRFLG register is held in the reset state1 when the initialization
mode is active (INITRQ = 1 and INITAK = 1). This register is writable again
as soon as the initialization mode is exited (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime when out of initialization mode, except RSTAT[1:0] and TSTAT[1:0] flags which are
read-only; write of 1 clears flag; write of 0 is ignored.
1. The RSTAT[1:0], TSTAT[1:0] bits are not affected by initialization mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
344
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-11. CANRFLG Register Field Descriptions
Field
Description
7
WUPIF
Wake-Up Interrupt Flag — If the MSCAN detects CAN bus activity while in sleep mode (see Section 12.4.6.4,
“MSCAN Sleep Mode,”) and WUPE = 1 in CANTCTL0 (see Section 12.3.2.1, “MSCAN Control Register 0
(CANCTL0)”), the module will set WUPIF. If not masked, a wake-up interrupt is pending while this flag is set.
0
No wake-up activity observed while in sleep mode
1
MSCAN detected activity on the CAN bus and requested wake-up
6
CSCIF
CAN Status Change Interrupt Flag — This flag is set when the MSCAN changes its current CAN bus status
due to the actual value of the transmit error counter (TEC) and the receive error counter (REC). An additional
4-bit (RSTAT[1:0], TSTAT[1:0]) status register, which is split into separate sections for TEC/REC, informs the
system on the actual CAN bus status (see Section 12.3.2.6, “MSCAN Receiver Interrupt Enable Register
(CANRIER)”). If not masked, an error interrupt is pending while this flag is set. CSCIF provides a blocking
interrupt. That guarantees that the receiver/transmitter status bits (RSTAT/TSTAT) are only updated when no CAN
status change interrupt is pending. If the TECs/RECs change their current value after the CSCIF is asserted,
which would cause an additional state change in the RSTAT/TSTAT bits, these bits keep their status until the
current CSCIF interrupt is cleared again.
0
No change in CAN bus status occurred since last interrupt
1
MSCAN changed current CAN bus status
5:4
Receiver Status Bits — The values of the error counters control the actual CAN bus status of the MSCAN. As
RSTAT[1:0] soon as the status change interrupt flag (CSCIF) is set, these bits indicate the appropriate receiver related CAN
bus status of the MSCAN. The coding for the bits RSTAT1, RSTAT0 is:
00
RxOK: 0 ≤ receive error counter ≤ 96
01
RxWRN: 96 < receive error counter ≤ 127
10
RxERR: 127 < receive error counter
11
Bus-off1: transmit error counter > 255
3:2
Transmitter Status Bits — The values of the error counters control the actual CAN bus status of the MSCAN.
TSTAT[1:0] As soon as the status change interrupt flag (CSCIF) is set, these bits indicate the appropriate transmitter related
CAN bus status of the MSCAN. The coding for the bits TSTAT1, TSTAT0 is:
00
TxOK: 0 ≤ transmit error counter ≤ 96
01
TxWRN: 96 < transmit error counter ≤ 127
10
TxERR: 127 < transmit error counter ≤ 255
11
Bus-Off: transmit error counter > 255
1
OVRIF
Overrun Interrupt Flag — This flag is set when a data overrun condition occurs. If not masked, an error interrupt
is pending while this flag is set.
0
No data overrun condition
1
A data overrun detected
0
RXF2
Receive Buffer Full Flag — RXF is set by the MSCAN when a new message is shifted in the receiver FIFO. This
flag indicates whether the shifted buffer is loaded with a correctly received message (matching identifier,
matching cyclic redundancy code (CRC) and no other errors detected). After the CPU has read that message
from the RxFG buffer in the receiver FIFO, the RXF flag must be cleared to release the buffer. A set RXF flag
prohibits the shifting of the next FIFO entry into the foreground buffer (RxFG). If not masked, a receive interrupt
is pending while this flag is set.
0
No new message available within the RxFG
1
The receiver FIFO is not empty. A new message is available in the RxFG
1
Redundant Information for the most critical CAN bus status which is “bus-off”. This only occurs if the Tx error counter exceeds
a number of 255 errors. Bus-off affects the receiver state. As soon as the transmitter leaves its bus-off state the receiver state
skips to RxOK too. Refer also to TSTAT[1:0] coding in this register.
2 To ensure data integrity, do not read the receive buffer registers while the RXF flag is cleared. For MCUs with dual CPUs,
reading the receive buffer registers while the RXF flag is cleared may result in a CPU fault condition.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
345
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.6
MSCAN Receiver Interrupt Enable Register (CANRIER)
This register contains the interrupt enable bits for the interrupt flags described in the CANRFLG register.
7
6
5
4
3
2
1
0
WUPIE
CSCIE
RSTATE1
RSTATE0
TSTATE1
TSTATE0
OVRIE
RXFIE
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 12-7. MSCAN Receiver Interrupt Enable Register (CANRIER)
NOTE
The CANRIER register is held in the reset state when the initialization mode
is active (INITRQ=1 and INITAK=1). This register is writable when not in
initialization mode (INITRQ=0 and INITAK=0).
The RSTATE[1:0], TSTATE[1:0] bits are not affected by initialization
mode.
Read: Anytime
Write: Anytime when not in initialization mode
Table 12-12. CANRIER Register Field Descriptions
Field
7
WUPIE1
6
CSCIE
Description
Wake-Up Interrupt Enable
0 No interrupt request is generated from this event.
1 A wake-up event causes a Wake-Up interrupt request.
CAN Status Change Interrupt Enable
0 No interrupt request is generated from this event.
1 A CAN Status Change event causes an error interrupt request.
5:4
Receiver Status Change Enable — These RSTAT enable bits control the sensitivity level in which receiver state
RSTATE[1:0] changes are causing CSCIF interrupts. Independent of the chosen sensitivity level the RSTAT flags continue to
indicate the actual receiver state and are only updated if no CSCIF interrupt is pending.
00 Do not generate any CSCIF interrupt caused by receiver state changes.
01 Generate CSCIF interrupt only if the receiver enters or leaves “bus-off” state. Discard other receiver state
changes for generating CSCIF interrupt.
10 Generate CSCIF interrupt only if the receiver enters or leaves “RxErr” or “bus-off”2 state. Discard other
receiver state changes for generating CSCIF interrupt.
11 Generate CSCIF interrupt on all state changes.
3:2
Transmitter Status Change Enable — These TSTAT enable bits control the sensitivity level in which transmitter
TSTATE[1:0] state changes are causing CSCIF interrupts. Independent of the chosen sensitivity level, the TSTAT flags
continue to indicate the actual transmitter state and are only updated if no CSCIF interrupt is pending.
00 Do not generate any CSCIF interrupt caused by transmitter state changes.
01 Generate CSCIF interrupt only if the transmitter enters or leaves “bus-off” state. Discard other transmitter
state changes for generating CSCIF interrupt.
10 Generate CSCIF interrupt only if the transmitter enters or leaves “TxErr” or “bus-off” state. Discard other
transmitter state changes for generating CSCIF interrupt.
11 Generate CSCIF interrupt on all state changes.
MC9S12HZ256 Data Sheet, Rev. 2.04
346
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-12. CANRIER Register Field Descriptions (continued)
Field
Description
1
OVRIE
Overrun Interrupt Enable
0 No interrupt request is generated from this event.
1 An overrun event causes an error interrupt request.
0
RXFIE
Receiver Full Interrupt Enable
0 No interrupt request is generated from this event.
1 A receive buffer full (successful message reception) event causes a receiver interrupt request.
1
WUPIE and WUPE (see Section 12.3.2.1, “MSCAN Control Register 0 (CANCTL0)”) must both be enabled if the recovery
mechanism from stop or wait is required.
2
Bus-off state is defined by the CAN standard (see Bosch CAN 2.0A/B protocol specification: for only transmitters. Because the
only possible state change for the transmitter from bus-off to TxOK also forces the receiver to skip its current state to RxOK,
the coding of the RXSTAT[1:0] flags define an additional bus-off state for the receiver (see Section 12.3.2.5, “MSCAN Receiver
Flag Register (CANRFLG)”).
12.3.2.7
MSCAN Transmitter Flag Register (CANTFLG)
The transmit buffer empty flags each have an associated interrupt enable bit in the CANTIER register.
R
7
6
5
4
3
0
0
0
0
0
2
1
0
TXE2
TXE1
TXE0
1
1
1
W
Reset:
0
0
0
0
0
= Unimplemented
Figure 12-8. MSCAN Transmitter Flag Register (CANTFLG)
NOTE
The CANTFLG register is held in the reset state when the initialization
mode is active (INITRQ = 1 and INITAK = 1). This register is writable when
not in initialization mode (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime for TXEx flags when not in initialization mode; write of 1 clears flag, write of 0 is ignored
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
347
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-13. CANTFLG Register Field Descriptions
Field
Description
2:0
TXE[2:0]
Transmitter Buffer Empty — This flag indicates that the associated transmit message buffer is empty, and thus
not scheduled for transmission. The CPU must clear the flag after a message is set up in the transmit buffer and
is due for transmission. The MSCAN sets the flag after the message is sent successfully. The flag is also set by
the MSCAN when the transmission request is successfully aborted due to a pending abort request (see
Section 12.3.2.9, “MSCAN Transmitter Message Abort Request Register (CANTARQ)”). If not masked, a
transmit interrupt is pending while this flag is set.
Clearing a TXEx flag also clears the corresponding ABTAKx (see Section 12.3.2.10, “MSCAN Transmitter
Message Abort Acknowledge Register (CANTAAK)”). When a TXEx flag is set, the corresponding ABTRQx bit
is cleared (see Section 12.3.2.9, “MSCAN Transmitter Message Abort Request Register (CANTARQ)”).
When listen-mode is active (see Section 12.3.2.2, “MSCAN Control Register 1 (CANCTL1)”) the TXEx flags
cannot be cleared and no transmission is started.
Read and write accesses to the transmit buffer will be blocked, if the corresponding TXEx bit is cleared
(TXEx = 0) and the buffer is scheduled for transmission.
0 The associated message buffer is full (loaded with a message due for transmission)
1 The associated message buffer is empty (not scheduled)
12.3.2.8
MSCAN Transmitter Interrupt Enable Register (CANTIER)
This register contains the interrupt enable bits for the transmit buffer empty interrupt flags.
R
7
6
5
4
3
0
0
0
0
0
2
1
0
TXEIE2
TXEIE1
TXEIE0
0
0
0
W
Reset:
0
0
0
0
0
= Unimplemented
Figure 12-9. MSCAN Transmitter Interrupt Enable Register (CANTIER)
NOTE
The CANTIER register is held in the reset state when the initialization mode
is active (INITRQ = 1 and INITAK = 1). This register is writable when not
in initialization mode (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime when not in initialization mode
Table 12-14. CANTIER Register Field Descriptions
Field
2:0
TXEIE[2:0]
Description
Transmitter Empty Interrupt Enable
0 No interrupt request is generated from this event.
1 A transmitter empty (transmit buffer available for transmission) event causes a transmitter empty interrupt
request.
MC9S12HZ256 Data Sheet, Rev. 2.04
348
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.9
MSCAN Transmitter Message Abort Request Register (CANTARQ)
The CANTARQ register allows abort request of queued messages as described below.
R
7
6
5
4
3
0
0
0
0
0
2
1
0
ABTRQ2
ABTRQ1
ABTRQ0
0
0
0
W
Reset:
0
0
0
0
0
= Unimplemented
Figure 12-10. MSCAN Transmitter Message Abort Request Register (CANTARQ)
NOTE
The CANTARQ register is held in the reset state when the initialization
mode is active (INITRQ = 1 and INITAK = 1). This register is writable when
not in initialization mode (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime when not in initialization mode
Table 12-15. CANTARQ Register Field Descriptions
Field
Description
2:0
Abort Request — The CPU sets the ABTRQx bit to request that a scheduled message buffer (TXEx = 0) be
ABTRQ[2:0] aborted. The MSCAN grants the request if the message has not already started transmission, or if the
transmission is not successful (lost arbitration or error). When a message is aborted, the associated TXE (see
Section 12.3.2.7, “MSCAN Transmitter Flag Register (CANTFLG)”) and abort acknowledge flags (ABTAK, see
Section 12.3.2.10, “MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)”) are set and a
transmit interrupt occurs if enabled. The CPU cannot reset ABTRQx. ABTRQx is reset whenever the associated
TXE flag is set.
0 No abort request
1 Abort request pending
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
349
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.10 MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
The CANTAAK register indicates the successful abort of a queued message, if requested by the
appropriate bits in the CANTARQ register.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
ABTAK2
ABTAK1
ABTAK0
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented
Figure 12-11. MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
NOTE
The CANTAAK register is held in the reset state when the initialization
mode is active (INITRQ = 1 and INITAK = 1).
Read: Anytime
Write: Unimplemented for ABTAKx flags
Table 12-16. CANTAAK Register Field Descriptions
Field
Description
2:0
Abort Acknowledge — This flag acknowledges that a message was aborted due to a pending abort request
ABTAK[2:0] from the CPU. After a particular message buffer is flagged empty, this flag can be used by the application
software to identify whether the message was aborted successfully or was sent anyway. The ABTAKx flag is
cleared whenever the corresponding TXE flag is cleared.
0 The message was not aborted.
1 The message was aborted.
MC9S12HZ256 Data Sheet, Rev. 2.04
350
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.11 MSCAN Transmit Buffer Selection Register (CANTBSEL)
The CANTBSEL register allows the selection of the actual transmit message buffer, which then will be
accessible in the CANTXFG register space.
R
7
6
5
4
3
0
0
0
0
0
2
1
0
TX2
TX1
TX0
0
0
0
W
Reset:
0
0
0
0
0
= Unimplemented
Figure 12-12. MSCAN Transmit Buffer Selection Register (CANTBSEL)
NOTE
The CANTBSEL register is held in the reset state when the initialization
mode is active (INITRQ = 1 and INITAK=1). This register is writable when
not in initialization mode (INITRQ = 0 and INITAK = 0).
Read: Find the lowest ordered bit set to 1, all other bits will be read as 0
Write: Anytime when not in initialization mode
Table 12-17. CANTBSEL Register Field Descriptions
Field
Description
2:0
TX[2:0]
Transmit Buffer Select — The lowest numbered bit places the respective transmit buffer in the CANTXFG
register space (e.g., TX1 = 1 and TX0 = 1 selects transmit buffer TX0; TX1 = 1 and TX0 = 0 selects transmit
buffer TX1). Read and write accesses to the selected transmit buffer will be blocked, if the corresponding TXEx
bit is cleared and the buffer is scheduled for transmission (see Section 12.3.2.7, “MSCAN Transmitter Flag
Register (CANTFLG)”).
0 The associated message buffer is deselected
1 The associated message buffer is selected, if lowest numbered bit
The following gives a short programming example of the usage of the CANTBSEL register:
To get the next available transmit buffer, application software must read the CANTFLG register and write
this value back into the CANTBSEL register. In this example Tx buffers TX1 and TX2 are available. The
value read from CANTFLG is therefore 0b0000_0110. When writing this value back to CANTBSEL, the
Tx buffer TX1 is selected in the CANTXFG because the lowest numbered bit set to 1 is at bit position 1.
Reading back this value out of CANTBSEL results in 0b0000_0010, because only the lowest numbered
bit position set to 1 is presented. This mechanism eases the application software the selection of the next
available Tx buffer.
•
•
•
LDD CANTFLG; value read is 0b0000_0110
STD CANTBSEL; value written is 0b0000_0110
LDD CANTBSEL; value read is 0b0000_0010
If all transmit message buffers are deselected, no accesses are allowed to the CANTXFG registers.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
351
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.12 MSCAN Identifier Acceptance Control Register (CANIDAC)
The CANIDAC register is used for identifier acceptance control as described below.
R
7
6
0
0
5
4
IDAM1
IDAM0
0
0
3
2
1
0
0
IDHIT2
IDHIT1
IDHIT0
0
0
0
0
W
Reset:
0
0
= Unimplemented
Figure 12-13. MSCAN Identifier Acceptance Control Register (CANIDAC)
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1), except bits IDHITx, which are
read-only
Table 12-18. CANIDAC Register Field Descriptions
Field
Description
5:4
IDAM[1:0]
Identifier Acceptance Mode — The CPU sets these flags to define the identifier acceptance filter organization
(see Section 12.4.3, “Identifier Acceptance Filter”). Table 12-19 summarizes the different settings. In filter closed
mode, no message is accepted such that the foreground buffer is never reloaded.
2:0
IDHIT[2:0]
Identifier Acceptance Hit Indicator — The MSCAN sets these flags to indicate an identifier acceptance hit (see
Section 12.4.3, “Identifier Acceptance Filter”). Table 12-20 summarizes the different settings.
Table 12-19. Identifier Acceptance Mode Settings
IDAM1
IDAM0
Identifier Acceptance Mode
0
0
Two 32-bit acceptance filters
0
1
Four 16-bit acceptance filters
1
0
Eight 8-bit acceptance filters
1
1
Filter closed
Table 12-20. Identifier Acceptance Hit Indication
IDHIT2
IDHIT1
IDHIT0
Identifier Acceptance Hit
0
0
0
Filter 0 hit
0
0
1
Filter 1 hit
0
1
0
Filter 2 hit
0
1
1
Filter 3 hit
1
0
0
Filter 4 hit
1
0
1
Filter 5 hit
1
1
0
Filter 6 hit
1
1
1
Filter 7 hit
The IDHITx indicators are always related to the message in the foreground buffer (RxFG). When a
message gets shifted into the foreground buffer of the receiver FIFO the indicators are updated as well.
MC9S12HZ256 Data Sheet, Rev. 2.04
352
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.13 MSCAN Reserved Register
reserved for factory testing of the MSCAN module and is not available in normal system operation modes.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented
Figure 12-14. MSCAN Reserved Register
Read: Always read 0x0000 in normal system operation modes
Write: Unimplemented in normal system operation modes
NOTE
Writing to this register when in special modes can alter the MSCAN
functionality.
12.3.2.14 MSCAN Receive Error Counter (CANRXERR)
This register reflects the status of the MSCAN receive error counter.
R
7
6
5
4
3
2
1
0
RXERR7
RXERR6
RXERR5
RXERR4
RXERR3
RXERR2
RXERR1
RXERR0
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented
Figure 12-15. MSCAN Receive Error Counter (CANRXERR)
Read: Only when in sleep mode (SLPRQ = 1 and SLPAK = 1) or initialization mode (INITRQ = 1 and
INITAK = 1)
Write: Unimplemented
NOTE
Reading this register when in any other mode other than sleep or
initialization mode may return an incorrect value. For MCUs with dual
CPUs, this may result in a CPU fault condition.
Writing to this register when in special modes can alter the MSCAN
functionality.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
353
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.15 MSCAN Transmit Error Counter (CANTXERR)
This register reflects the status of the MSCAN transmit error counter.
R
7
6
5
4
3
2
1
0
TXERR7
TXERR6
TXERR5
TXERR4
TXERR3
TXERR2
TXERR1
TXERR0
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented
Figure 12-16. MSCAN Transmit Error Counter (CANTXERR)
Read: Only when in sleep mode (SLPRQ = 1 and SLPAK = 1) or initialization mode (INITRQ = 1 and
INITAK = 1)
Write: Unimplemented
NOTE
Reading this register when in any other mode other than sleep or
initialization mode, may return an incorrect value. For MCUs with dual
CPUs, this may result in a CPU fault condition.
Writing to this register when in special modes can alter the MSCAN
functionality.
MC9S12HZ256 Data Sheet, Rev. 2.04
354
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.16 MSCAN Identifier Acceptance Registers (CANIDAR0-7)
On reception, each message is written into the background receive buffer. The CPU is only signalled to
read the message if it passes the criteria in the identifier acceptance and identifier mask registers
(accepted); otherwise, the message is overwritten by the next message (dropped).
The acceptance registers of the MSCAN are applied on the IDR0–IDR3 registers (see Section 12.3.3.1,
“Identifier Registers (IDR0–IDR3)”) of incoming messages in a bit by bit manner (see Section 12.4.3,
“Identifier Acceptance Filter”).
For extended identifiers, all four acceptance and mask registers are applied. For standard identifiers, only
the first two (CANIDAR0/1, CANIDMR0/1) are applied.
Module Base + 0x0010 (CANIDAR0)
0x0011 (CANIDAR1)
0x0012 (CANIDAR2)
0x0013 (CANIDAR3)
R
W
Reset
R
W
Reset
R
W
Reset
R
W
Reset
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
Figure 12-17. MSCAN Identifier Acceptance Registers (First Bank) — CANIDAR0–CANIDAR3
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
Table 12-21. CANIDAR0–CANIDAR3 Register Field Descriptions
Field
Description
7:0
AC[7:0]
Acceptance Code Bits — AC[7:0] comprise a user-defined sequence of bits with which the corresponding bits
of the related identifier register (IDRn) of the receive message buffer are compared. The result of this comparison
is then masked with the corresponding identifier mask register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
355
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Module Base + 0x0018 (CANIDAR4)
0x0019 (CANIDAR5)
0x001A (CANIDAR6)
0x001B (CANIDAR7)
R
W
Reset
R
W
Reset
R
W
Reset
R
W
Reset
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AC7
AC6
AC5
AC4
AC3
AC2
AC1
AC0
0
0
0
0
0
0
0
0
Figure 12-18. MSCAN Identifier Acceptance Registers (Second Bank) — CANIDAR4–CANIDAR7
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
Table 12-22. CANIDAR4–CANIDAR7 Register Field Descriptions
Field
Description
7:0
AC[7:0]
Acceptance Code Bits — AC[7:0] comprise a user-defined sequence of bits with which the corresponding bits
of the related identifier register (IDRn) of the receive message buffer are compared. The result of this comparison
is then masked with the corresponding identifier mask register.
MC9S12HZ256 Data Sheet, Rev. 2.04
356
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.2.17 MSCAN Identifier Mask Registers (CANIDMR0–CANIDMR7)
The identifier mask register specifies which of the corresponding bits in the identifier acceptance register
are relevant for acceptance filtering. To receive standard identifiers in 32 bit filter mode, it is required to
program the last three bits (AM[2:0]) in the mask registers CANIDMR1 and CANIDMR5 to “don’t care.”
To receive standard identifiers in 16 bit filter mode, it is required to program the last three bits (AM[2:0])
in the mask registers CANIDMR1, CANIDMR3, CANIDMR5, and CANIDMR7 to “don’t care.”
Module Base + 0x0014 (CANIDMR0)
0x0015 (CANIDMR1)
0x0016 (CANIDMR2)
0x0017 (CANIDMR3)
R
W
Reset
R
W
Reset
R
W
Reset
R
W
Reset
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
Figure 12-19. MSCAN Identifier Mask Registers (First Bank) — CANIDMR0–CANIDMR3
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
Table 12-23. CANIDMR0–CANIDMR3 Register Field Descriptions
Field
Description
7:0
AM[7:0]
Acceptance Mask Bits — If a particular bit in this register is cleared, this indicates that the corresponding bit in
the identifier acceptance register must be the same as its identifier bit before a match is detected. The message
is accepted if all such bits match. If a bit is set, it indicates that the state of the corresponding bit in the identifier
acceptance register does not affect whether or not the message is accepted.
0 Match corresponding acceptance code register and identifier bits
1 Ignore corresponding acceptance code register bit
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
357
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Module Base + 0x001C (CANIDMR4)
0x001D (CANIDMR5)
0x001E (CANIDMR6)
0x001F (CANIDMR7)
R
W
Reset
R
W
Reset
R
W
Reset
R
W
Reset
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
7
6
5
4
3
2
1
0
AM7
AM6
AM5
AM4
AM3
AM2
AM1
AM0
0
0
0
0
0
0
0
0
Figure 12-20. MSCAN Identifier Mask Registers (Second Bank) — CANIDMR4–CANIDMR7
Read: Anytime
Write: Anytime in initialization mode (INITRQ = 1 and INITAK = 1)
Table 12-24. CANIDMR4–CANIDMR7 Register Field Descriptions
Field
Description
7:0
AM[7:0]
Acceptance Mask Bits — If a particular bit in this register is cleared, this indicates that the corresponding bit in
the identifier acceptance register must be the same as its identifier bit before a match is detected. The message
is accepted if all such bits match. If a bit is set, it indicates that the state of the corresponding bit in the identifier
acceptance register does not affect whether or not the message is accepted.
0 Match corresponding acceptance code register and identifier bits
1 Ignore corresponding acceptance code register bit
MC9S12HZ256 Data Sheet, Rev. 2.04
358
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.3.3
Programmer’s Model of Message Storage
The following section details the organization of the receive and transmit message buffers and the
associated control registers.
To simplify the programmer interface, the receive and transmit message buffers have the same outline.
Each message buffer allocates 16 bytes in the memory map containing a 13 byte data structure.
An additional transmit buffer priority register (TBPR) is defined for the transmit buffers. Within the last
two bytes of this memory map, the MSCAN stores a special 16-bit time stamp, which is sampled from an
internal timer after successful transmission or reception of a message. This feature is only available for
transmit and receiver buffers, if the TIME bit is set (see Section 12.3.2.1, “MSCAN Control Register 0
(CANCTL0)”).
The time stamp register is written by the MSCAN. The CPU can only read these registers.
Table 12-25. Message Buffer Organization
Offset
Address
Register
0x00X0
Identifier Register 0
0x00X1
Identifier Register 1
0x00X2
Identifier Register 2
0x00X3
Identifier Register 3
0x00X4
Data Segment Register 0
0x00X5
Data Segment Register 1
0x00X6
Data Segment Register 2
0x00X7
Data Segment Register 3
0x00X8
Data Segment Register 4
0x00X9
Data Segment Register 5
0x00XA
Data Segment Register 6
0x00XB
Data Segment Register 7
0x00XC
Data Length Register
0x00XD
Transmit Buffer Priority Register1
0x00XE
Time Stamp Register (High Byte)2
0x00XF
Time Stamp Register (Low Byte)3
Access
1
Not applicable for receive buffers
Read-only for CPU
3 Read-only for CPU
2
Figure 12-21 shows the common 13-byte data structure of receive and transmit buffers for extended
identifiers. The mapping of standard identifiers into the IDR registers is shown in Figure 12-22.
All bits of the receive and transmit buffers are ‘x’ out of reset because of RAM-based implementation1.
All reserved or unused bits of the receive and transmit buffers always read ‘x’.
1. Exception: The transmit priority registers are 0 out of reset.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
359
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Register
Name
IDR0
IDR1
R
W
R
W
R
IDR2
W
IDR3
W
R
R
DSR0
W
R
DSR1
W
R
DSR2
W
DSR3
W
R
R
DSR4
W
R
DSR5
W
DSR6
W
R
R
DSR7
W
Bit 7
6
5
4
3
2
1
Bit0
ID28
ID27
ID26
ID25
ID24
ID23
ID22
ID21
ID20
ID19
ID18
SRR (=1)
IDE (=1)
ID17
ID16
ID15
ID14
ID13
ID12
ID11
ID10
ID9
ID8
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
RTR
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DLC3
DLC2
DLC1
DLC0
R
DLR
W
= Unused, always read ‘x’
Figure 12-21. Receive/Transmit Message Buffer — Extended Identifier Mapping
Read: For transmit buffers, anytime when TXEx flag is set (see Section 12.3.2.7, “MSCAN Transmitter
Flag Register (CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see
Section 12.3.2.11, “MSCAN Transmit Buffer Selection Register (CANTBSEL)”). For receive buffers,
only when RXF flag is set (see Section 12.3.2.5, “MSCAN Receiver Flag Register (CANRFLG)”).
MC9S12HZ256 Data Sheet, Rev. 2.04
360
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Write: For transmit buffers, anytime when TXEx flag is set (see Section 12.3.2.7, “MSCAN Transmitter
Flag Register (CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see
Section 12.3.2.11, “MSCAN Transmit Buffer Selection Register (CANTBSEL)”). Unimplemented for
receive buffers.
Reset: Undefined (0x00XX) because of RAM-based implementation
Register
Name
R
IDR0
W
R
IDR1
W
Bit 7
6
5
4
3
2
1
Bit 0
ID10
ID9
ID8
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
RTR
IDE (=0)
R
IDR2
W
R
IDR3
W
= Unused, always read ‘x’
Figure 12-22. Receive/Transmit Message Buffer — Standard Identifier Mapping
12.3.3.1
Identifier Registers (IDR0–IDR3)
The identifier registers for an extended format identifier consist of a total of 32 bits; ID[28:0], SRR, IDE,
and RTR bits. The identifier registers for a standard format identifier consist of a total of 13 bits; ID[10:0],
RTR, and IDE bits.
12.3.3.1.1
IDR0–IDR3 for Extended Identifier Mapping
7
6
5
4
3
2
1
0
ID28
ID27
ID26
ID25
ID24
ID23
ID22
ID21
x
x
x
x
x
x
x
x
R
W
Reset:
Figure 12-23. Identifier Register 0 (IDR0) — Extended Identifier Mapping
Table 12-26. IDR0 Register Field Descriptions — Extended
Field
Description
7:0
ID[28:21]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
361
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
7
6
5
4
3
2
1
0
ID20
ID19
ID18
SRR (=1)
IDE (=1)
ID17
ID16
ID15
x
x
x
x
x
x
x
x
R
W
Reset:
Figure 12-24. Identifier Register 1 (IDR1) — Extended Identifier Mapping
Table 12-27. IDR1 Register Field Descriptions — Extended
Field
Description
7:5
ID[20:18]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
4
SRR
Substitute Remote Request — This fixed recessive bit is used only in extended format. It must be set to 1 by
the user for transmission buffers and is stored as received on the CAN bus for receive buffers.
3
IDE
ID Extended — This flag indicates whether the extended or standard identifier format is applied in this buffer. In
the case of a receive buffer, the flag is set as received and indicates to the CPU how to process the buffer
identifier registers. In the case of a transmit buffer, the flag indicates to the MSCAN what type of identifier to send.
0 Standard format (11 bit)
1 Extended format (29 bit)
2:0
ID[17:15]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
7
6
5
4
3
2
1
0
ID14
ID13
ID12
ID11
ID10
ID9
ID8
ID7
x
x
x
x
x
x
x
x
R
W
Reset:
Figure 12-25. Identifier Register 2 (IDR2) — Extended Identifier Mapping
Table 12-28. IDR2 Register Field Descriptions — Extended
Field
Description
7:0
ID[14:7]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
MC9S12HZ256 Data Sheet, Rev. 2.04
362
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
7
6
5
4
3
2
1
0
ID6
ID5
ID4
ID3
ID2
ID1
ID0
RTR
x
x
x
x
x
x
x
x
R
W
Reset:
Figure 12-26. Identifier Register 3 (IDR3) — Extended Identifier Mapping
Table 12-29. IDR3 Register Field Descriptions — Extended
Field
Description
7:1
ID[6:0]
Extended Format Identifier — The identifiers consist of 29 bits (ID[28:0]) for the extended format. ID28 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number.
0
RTR
Remote Transmission Request — This flag reflects the status of the remote transmission request bit in the
CAN frame. In the case of a receive buffer, it indicates the status of the received frame and supports the
transmission of an answering frame in software. In the case of a transmit buffer, this flag defines the setting of
the RTR bit to be sent.
0 Data frame
1 Remote frame
12.3.3.1.2
IDR0–IDR3 for Standard Identifier Mapping
7
6
5
4
3
2
1
0
ID10
ID9
ID8
ID7
ID6
ID5
ID4
ID3
x
x
x
x
x
x
x
x
R
W
Reset:
Figure 12-27. Identifier Register 0 — Standard Mapping
Table 12-30. IDR0 Register Field Descriptions — Standard
Field
Description
7:0
ID[10:3]
Standard Format Identifier — The identifiers consist of 11 bits (ID[10:0]) for the standard format. ID10 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number. See also ID bits in Table 12-31.
7
6
5
4
3
ID2
ID1
ID0
RTR
IDE (=0)
x
x
x
x
x
2
1
0
x
x
x
R
W
Reset:
= Unused; always read ‘x’
Figure 12-28. Identifier Register 1 — Standard Mapping
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
363
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-31. IDR1 Register Field Descriptions
Field
Description
7:5
ID[2:0]
Standard Format Identifier — The identifiers consist of 11 bits (ID[10:0]) for the standard format. ID10 is the
most significant bit and is transmitted first on the CAN bus during the arbitration procedure. The priority of an
identifier is defined to be highest for the smallest binary number. See also ID bits in Table 12-30.
4
RTR
Remote Transmission Request — This flag reflects the status of the Remote Transmission Request bit in the
CAN frame. In the case of a receive buffer, it indicates the status of the received frame and supports the
transmission of an answering frame in software. In the case of a transmit buffer, this flag defines the setting of
the RTR bit to be sent.
0 Data frame
1 Remote frame
3
IDE
ID Extended — This flag indicates whether the extended or standard identifier format is applied in this buffer. In
the case of a receive buffer, the flag is set as received and indicates to the CPU how to process the buffer
identifier registers. In the case of a transmit buffer, the flag indicates to the MSCAN what type of identifier to send.
0 Standard format (11 bit)
1 Extended format (29 bit)
7
6
5
4
3
2
1
0
x
x
x
x
x
x
x
x
R
W
Reset:
= Unused; always read ‘x’
Figure 12-29. Identifier Register 2 — Standard Mapping
7
6
5
4
3
2
1
0
x
x
x
x
x
x
x
x
R
W
Reset:
= Unused; always read ‘x’
Figure 12-30. Identifier Register 3 — Standard Mapping
12.3.3.2
Data Segment Registers (DSR0-7)
The eight data segment registers, each with bits DB[7:0], contain the data to be transmitted or received.
The number of bytes to be transmitted or received is determined by the data length code in the
corresponding DLR register.
MC9S12HZ256 Data Sheet, Rev. 2.04
364
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Module Base + 0x0004 (DSR0)
0x0005 (DSR1)
0x0006 (DSR2)
0x0007 (DSR3)
0x0008 (DSR4)
0x0009 (DSR5)
0x000A (DSR6)
0x000B (DSR7)
7
6
5
4
3
2
1
0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
x
x
x
x
x
x
x
x
R
W
Reset:
Figure 12-31. Data Segment Registers (DSR0–DSR7) — Extended Identifier Mapping
Table 12-32. DSR0–DSR7 Register Field Descriptions
Field
Description
7:0
DB[7:0]
Data bits 7:0
12.3.3.3
Data Length Register (DLR)
This register keeps the data length field of the CAN frame.
7
6
5
4
3
2
1
0
DLC3
DLC2
DLC1
DLC0
x
x
x
x
R
W
Reset:
x
x
x
x
= Unused; always read “x”
Figure 12-32. Data Length Register (DLR) — Extended Identifier Mapping
Table 12-33. DLR Register Field Descriptions
Field
Description
3:0
DLC[3:0]
Data Length Code Bits — The data length code contains the number of bytes (data byte count) of the respective
message. During the transmission of a remote frame, the data length code is transmitted as programmed while
the number of transmitted data bytes is always 0. The data byte count ranges from 0 to 8 for a data frame.
Table 12-34 shows the effect of setting the DLC bits.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
365
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-34. Data Length Codes
Data Length Code
12.3.3.4
DLC3
DLC2
DLC1
DLC0
Data Byte
Count
0
0
0
0
0
0
0
0
1
1
0
0
1
0
2
0
0
1
1
3
0
1
0
0
4
0
1
0
1
5
0
1
1
0
6
0
1
1
1
7
1
0
0
0
8
Transmit Buffer Priority Register (TBPR)
This register defines the local priority of the associated message buffer. The local priority is used for the
internal prioritization process of the MSCAN and is defined to be highest for the smallest binary number.
The MSCAN implements the following internal prioritization mechanisms:
• All transmission buffers with a cleared TXEx flag participate in the prioritization immediately
before the SOF (start of frame) is sent.
• The transmission buffer with the lowest local priority field wins the prioritization.
In cases of more than one buffer having the same lowest priority, the message buffer with the lower index
number wins.
7
6
5
4
3
2
1
0
PRIO7
PRIO6
PRIO5
PRIO4
PRIO3
PRIO2
PRIO1
PRIO0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 12-33. Transmit Buffer Priority Register (TBPR)
Read: Anytime when TXEx flag is set (see Section 12.3.2.7, “MSCAN Transmitter Flag Register
(CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see Section 12.3.2.11,
“MSCAN Transmit Buffer Selection Register (CANTBSEL)”).
Write: Anytime when TXEx flag is set (see Section 12.3.2.7, “MSCAN Transmitter Flag Register
(CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see Section 12.3.2.11,
“MSCAN Transmit Buffer Selection Register (CANTBSEL)”).
12.3.3.5
Time Stamp Register (TSRH–TSRL)
If the TIME bit is enabled, the MSCAN will write a special time stamp to the respective registers in the
active transmit or receive buffer as soon as a message has been acknowledged on the CAN bus (see
MC9S12HZ256 Data Sheet, Rev. 2.04
366
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Section 12.3.2.1, “MSCAN Control Register 0 (CANCTL0)”). The time stamp is written on the bit sample
point for the recessive bit of the ACK delimiter in the CAN frame. In case of a transmission, the CPU can
only read the time stamp after the respective transmit buffer has been flagged empty.
The timer value, which is used for stamping, is taken from a free running internal CAN bit clock. A timer
overrun is not indicated by the MSCAN. The timer is reset (all bits set to 0) during initialization mode. The
CPU can only read the time stamp registers.
R
7
6
5
4
3
2
1
0
TSR15
TSR14
TSR13
TSR12
TSR11
TSR10
TSR9
TSR8
x
x
x
x
x
x
x
x
W
Reset:
Figure 12-34. Time Stamp Register — High Byte (TSRH)
R
7
6
5
4
3
2
1
0
TSR7
TSR6
TSR5
TSR4
TSR3
TSR2
TSR1
TSR0
x
x
x
x
x
x
x
x
W
Reset:
Figure 12-35. Time Stamp Register — Low Byte (TSRL)
Read: Anytime when TXEx flag is set (see Section 12.3.2.7, “MSCAN Transmitter Flag Register
(CANTFLG)”) and the corresponding transmit buffer is selected in CANTBSEL (see Section 12.3.2.11,
“MSCAN Transmit Buffer Selection Register (CANTBSEL)”).
Write: Unimplemented
12.4
12.4.1
Functional Description
General
This section provides a complete functional description of the MSCAN. It describes each of the features
and modes listed in the introduction.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
367
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.2
Message Storage
CAN
Receive / Transmit
Engine
CPU12
Memory Mapped
I/O
Rx0
RXF
Receiver
TxBG
Tx0
MSCAN
TxFG
Tx1
TxBG
Tx2
Transmitter
CPU bus
RxFG
RxBG
MSCAN
Rx1
Rx2
Rx3
Rx4
TXE0
PRIO
TXE1
CPU bus
PRIO
TXE2
PRIO
Figure 12-36. User Model for Message Buffer Organization
MSCAN facilitates a sophisticated message storage system which addresses the requirements of a broad
range of network applications.
MC9S12HZ256 Data Sheet, Rev. 2.04
368
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.2.1
Message Transmit Background
Modern application layer software is built upon two fundamental assumptions:
• Any CAN node is able to send out a stream of scheduled messages without releasing the CAN bus
between the two messages. Such nodes arbitrate for the CAN bus immediately after sending the
previous message and only release the CAN bus in case of lost arbitration.
• The internal message queue within any CAN node is organized such that the highest priority
message is sent out first, if more than one message is ready to be sent.
The behavior described in the bullets above cannot be achieved with a single transmit buffer. That buffer
must be reloaded immediately after the previous message is sent. This loading process lasts a finite amount
of time and must be completed within the inter-frame sequence (IFS) to be able to send an uninterrupted
stream of messages. Even if this is feasible for limited CAN bus speeds, it requires that the CPU reacts
with short latencies to the transmit interrupt.
A double buffer scheme de-couples the reloading of the transmit buffer from the actual message sending
and, therefore, reduces the reactiveness requirements of the CPU. Problems can arise if the sending of a
message is finished while the CPU re-loads the second buffer. No buffer would then be ready for
transmission, and the CAN bus would be released.
At least three transmit buffers are required to meet the first of the above requirements under all
circumstances. The MSCAN has three transmit buffers.
The second requirement calls for some sort of internal prioritization which the MSCAN implements with
the “local priority” concept described in Section 12.4.2.2, “Transmit Structures.”
12.4.2.2
Transmit Structures
The MSCAN triple transmit buffer scheme optimizes real-time performance by allowing multiple
messages to be set up in advance. The three buffers are arranged as shown in Figure 12-36.
All three buffers have a 13-byte data structure similar to the outline of the receive buffers (see
Section 12.3.3, “Programmer’s Model of Message Storage”). An additional Section 12.3.3.4, “Transmit
Buffer Priority Register (TBPR) contains an 8-bit local priority field (PRIO) (see Section 12.3.3.4,
“Transmit Buffer Priority Register (TBPR)”). The remaining two bytes are used for time stamping of a
message, if required (see Section 12.3.3.5, “Time Stamp Register (TSRH–TSRL)”).
To transmit a message, the CPU must identify an available transmit buffer, which is indicated by a set
transmitter buffer empty (TXEx) flag (see Section 12.3.2.7, “MSCAN Transmitter Flag Register
(CANTFLG)”). If a transmit buffer is available, the CPU must set a pointer to this buffer by writing to the
CANTBSEL register (see Section 12.3.2.11, “MSCAN Transmit Buffer Selection Register
(CANTBSEL)”). This makes the respective buffer accessible within the CANTXFG address space (see
Section 12.3.3, “Programmer’s Model of Message Storage”). The algorithmic feature associated with the
CANTBSEL register simplifies the transmit buffer selection. In addition, this scheme makes the handler
software simpler because only one address area is applicable for the transmit process, and the required
address space is minimized.
The CPU then stores the identifier, the control bits, and the data content into one of the transmit buffers.
Finally, the buffer is flagged as ready for transmission by clearing the associated TXE flag.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
369
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
The MSCAN then schedules the message for transmission and signals the successful transmission of the
buffer by setting the associated TXE flag. A transmit interrupt (see Section 12.4.8.2, “Transmit Interrupt”)
is generated1 when TXEx is set and can be used to drive the application software to re-load the buffer.
If more than one buffer is scheduled for transmission when the CAN bus becomes available for arbitration,
the MSCAN uses the local priority setting of the three buffers to determine the prioritization. For this
purpose, every transmit buffer has an 8-bit local priority field (PRIO). The application software programs
this field when the message is set up. The local priority reflects the priority of this particular message
relative to the set of messages being transmitted from this node. The lowest binary value of the PRIO field
is defined to be the highest priority. The internal scheduling process takes place whenever the MSCAN
arbitrates for the CAN bus. This is also the case after the occurrence of a transmission error.
When a high priority message is scheduled by the application software, it may become necessary to abort
a lower priority message in one of the three transmit buffers. Because messages that are already in
transmission cannot be aborted, the user must request the abort by setting the corresponding abort request
bit (ABTRQ) (see Section 12.3.2.9, “MSCAN Transmitter Message Abort Request Register
(CANTARQ)”.) The MSCAN then grants the request, if possible, by:
1. Setting the corresponding abort acknowledge flag (ABTAK) in the CANTAAK register.
2. Setting the associated TXE flag to release the buffer.
3. Generating a transmit interrupt. The transmit interrupt handler software can determine from the
setting of the ABTAK flag whether the message was aborted (ABTAK = 1) or sent (ABTAK = 0).
12.4.2.3
Receive Structures
The received messages are stored in a five stage input FIFO. The five message buffers are alternately
mapped into a single memory area (see Figure 12-36). The background receive buffer (RxBG) is
exclusively associated with the MSCAN, but the foreground receive buffer (RxFG) is addressable by the
CPU (see Figure 12-36). This scheme simplifies the handler software because only one address area is
applicable for the receive process.
All receive buffers have a size of 15 bytes to store the CAN control bits, the identifier (standard or
extended), the data contents, and a time stamp, if enabled (see Section 12.3.3, “Programmer’s Model of
Message Storage”).
The receiver full flag (RXF) (see Section 12.3.2.5, “MSCAN Receiver Flag Register (CANRFLG)”)
signals the status of the foreground receive buffer. When the buffer contains a correctly received message
with a matching identifier, this flag is set.
On reception, each message is checked to see whether it passes the filter (see Section 12.4.3, “Identifier
Acceptance Filter”) and simultaneously is written into the active RxBG. After successful reception of a
valid message, the MSCAN shifts the content of RxBG into the receiver FIFO2, sets the RXF flag, and
generates a receive interrupt (see Section 12.4.8.3, “Receive Interrupt”) to the CPU3. The user’s receive
handler must read the received message from the RxFG and then reset the RXF flag to acknowledge the
interrupt and to release the foreground buffer. A new message, which can follow immediately after the IFS
1. The transmit interrupt occurs only if not masked. A polling scheme can be applied on TXEx also.
2. Only if the RXF flag is not set.
3. The receive interrupt occurs only if not masked. A polling scheme can be applied on RXF also.
MC9S12HZ256 Data Sheet, Rev. 2.04
370
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
field of the CAN frame, is received into the next available RxBG. If the MSCAN receives an invalid
message in its RxBG (wrong identifier, transmission errors, etc.) the actual contents of the buffer will be
over-written by the next message. The buffer will then not be shifted into the FIFO.
When the MSCAN module is transmitting, the MSCAN receives its own transmitted messages into the
background receive buffer, RxBG, but does not shift it into the receiver FIFO, generate a receive interrupt,
or acknowledge its own messages on the CAN bus. The exception to this rule is in loopback mode (see
Section 12.3.2.2, “MSCAN Control Register 1 (CANCTL1)”) where the MSCAN treats its own messages
exactly like all other incoming messages. The MSCAN receives its own transmitted messages in the event
that it loses arbitration. If arbitration is lost, the MSCAN must be prepared to become a receiver.
An overrun condition occurs when all receive message buffers in the FIFO are filled with correctly
received messages with accepted identifiers and another message is correctly received from the CAN bus
with an accepted identifier. The latter message is discarded and an error interrupt with overrun indication
is generated if enabled (see Section 12.4.8.5, “Error Interrupt”). The MSCAN remains able to transmit
messages while the receiver FIFO being filled, but all incoming messages are discarded. As soon as a
receive buffer in the FIFO is available again, new valid messages will be accepted.
12.4.3
Identifier Acceptance Filter
The MSCAN identifier acceptance registers (see Section 12.3.2.12, “MSCAN Identifier Acceptance
Control Register (CANIDAC)”) define the acceptable patterns of the standard or extended identifier
(ID[10:0] or ID[28:0]). Any of these bits can be marked ‘don’t care’ in the MSCAN identifier mask
registers (see Section 12.3.2.17, “MSCAN Identifier Mask Registers (CANIDMR0–CANIDMR7)”).
A filter hit is indicated to the application software by a set receive buffer full flag (RXF = 1) and three bits
in the CANIDAC register (see Section 12.3.2.12, “MSCAN Identifier Acceptance Control Register
(CANIDAC)”). These identifier hit flags (IDHIT[2:0]) clearly identify the filter section that caused the
acceptance. They simplify the application software’s task to identify the cause of the receiver interrupt. If
more than one hit occurs (two or more filters match), the lower hit has priority.
A very flexible programmable generic identifier acceptance filter has been introduced to reduce the CPU
interrupt loading. The filter is programmable to operate in four different modes (see Bosch CAN 2.0A/B
protocol specification):
• Two identifier acceptance filters, each to be applied to:
— The full 29 bits of the extended identifier and to the following bits of the CAN 2.0B frame:
– Remote transmission request (RTR)
– Identifier extension (IDE)
– Substitute remote request (SRR)
— The 11 bits of the standard identifier plus the RTR and IDE bits of the CAN 2.0A/B messages1.
This mode implements two filters for a full length CAN 2.0B compliant extended identifier.
Figure 12-37 shows how the first 32-bit filter bank (CANIDAR0–CANIDAR3,
CANIDMR0–CANIDMR3) produces a filter 0 hit. Similarly, the second filter bank
(CANIDAR4–CANIDAR7, CANIDMR4–CANIDMR7) produces a filter 1 hit.
1.Although this mode can be used for standard identifiers, it is recommended to use the four or eight identifier acceptance
filters for standard identifiers
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
371
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
•
•
•
Four identifier acceptance filters, each to be applied to
— a) the 14 most significant bits of the extended identifier plus the SRR and IDE bits of CAN 2.0B
messages or
— b) the 11 bits of the standard identifier, the RTR and IDE bits of CAN 2.0A/B messages.
Figure 12-38 shows how the first 32-bit filter bank (CANIDAR0–CANIDA3,
CANIDMR0–3CANIDMR) produces filter 0 and 1 hits. Similarly, the second filter bank
(CANIDAR4–CANIDAR7, CANIDMR4–CANIDMR7) produces filter 2 and 3 hits.
Eight identifier acceptance filters, each to be applied to the first 8 bits of the identifier. This mode
implements eight independent filters for the first 8 bits of a CAN 2.0A/B compliant standard
identifier or a CAN 2.0B compliant extended identifier. Figure 12-39 shows how the first 32-bit
filter bank (CANIDAR0–CANIDAR3, CANIDMR0–CANIDMR3) produces filter 0 to 3 hits.
Similarly, the second filter bank (CANIDAR4–CANIDAR7, CANIDMR4–CANIDMR7)
produces filter 4 to 7 hits.
Closed filter. No CAN message is copied into the foreground buffer RxFG, and the RXF flag is
never set.
CAN 2.0B
Extended Identifier ID28
IDR0
ID21
ID20
IDR1
CAN 2.0A/B
Standard Identifier ID10
IDR0
ID3
ID2
IDR1
ID15
IDE
ID14
IDR2
ID7
ID6
IDR3
RTR
ID10
IDR2
ID3
ID10
IDR3
ID3
AM7
CANIDMR0
AM0
AM7
CANIDMR1
AM0
AM7
CANIDMR2
AM0
AM7
CANIDMR3
AM0
AC7
CANIDAR0
AC0
AC7
CANIDAR1
AC0
AC7
CANIDAR2
AC0
AC7
CANIDAR3
AC0
ID Accepted (Filter 0 Hit)
Figure 12-37. 32-bit Maskable Identifier Acceptance Filter
MC9S12HZ256 Data Sheet, Rev. 2.04
372
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
CAN 2.0B
Extended Identifier
ID28
IDR0
ID21
ID20
IDR1
CAN 2.0A/B
Standard Identifier
ID10
IDR0
ID3
ID2
IDR1
AM7
CANIDMR0
AM0
AM7
CANIDMR1
AM0
AC7
CANIDAR0
AC0
AC7
CANIDAR1
AC0
ID15
IDE
ID14
IDR2
ID7
ID6
IDR3
RTR
ID10
IDR2
ID3
ID10
IDR3
ID3
ID Accepted (Filter 0 Hit)
AM7
CANIDMR2
AM0
AM7
CANIDMR3
AM0
AC7
CANIDAR2
AC0
AC7
CANIDAR3
AC0
ID Accepted (Filter 1 Hit)
Figure 12-38. 16-bit Maskable Identifier Acceptance Filters
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
373
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
CAN 2.0B
Extended Identifier ID28
IDR0
ID21
ID20
IDR1
CAN 2.0A/B
Standard Identifier ID10
IDR0
ID3
ID2
IDR1
AM7
CIDMR0
AM0
AC7
CIDAR0
AC0
ID15
IDE
ID14
IDR2
ID7
ID6
IDR3
RTR
ID10
IDR2
ID3
ID10
IDR3
ID3
ID Accepted (Filter 0 Hit)
AM7
CIDMR1
AM0
AC7
CIDAR1
AC0
ID Accepted (Filter 1 Hit)
AM7
CIDMR2
AM0
AC7
CIDAR2
AC0
ID Accepted (Filter 2 Hit)
AM7
CIDMR3
AM0
AC7
CIDAR3
AC0
ID Accepted (Filter 3 Hit)
Figure 12-39. 8-bit Maskable Identifier Acceptance Filters
MC9S12HZ256 Data Sheet, Rev. 2.04
374
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.3.1
Protocol Violation Protection
The MSCAN protects the user from accidentally violating the CAN protocol through programming errors.
The protection logic implements the following features:
• The receive and transmit error counters cannot be written or otherwise manipulated.
• All registers which control the configuration of the MSCAN cannot be modified while the MSCAN
is on-line. The MSCAN has to be in Initialization Mode. The corresponding INITRQ/INITAK
handshake bits in the CANCTL0/CANCTL1 registers (see Section 12.3.2.1, “MSCAN Control
Register 0 (CANCTL0)”) serve as a lock to protect the following registers:
— MSCAN control 1 register (CANCTL1)
— MSCAN bus timing registers 0 and 1 (CANBTR0, CANBTR1)
— MSCAN identifier acceptance control register (CANIDAC)
— MSCAN identifier acceptance registers (CANIDAR0–CANIDAR7)
— MSCAN identifier mask registers (CANIDMR0–CANIDMR7)
• The TXCAN pin is immediately forced to a recessive state when the MSCAN goes into the power
down mode or initialization mode (see Section 12.4.6.6, “MSCAN Power Down Mode,” and
Section 12.4.6.5, “MSCAN Initialization Mode”).
• The MSCAN enable bit (CANE) is writable only once in normal system operation modes, which
provides further protection against inadvertently disabling the MSCAN.
12.4.3.2
Clock System
Figure 12-40 shows the structure of the MSCAN clock generation circuitry.
MSCAN
Bus Clock
CANCLK
CLKSRC
Prescaler
(1 .. 64)
Time quanta clock (Tq)
CLKSRC
Oscillator Clock
Figure 12-40. MSCAN Clocking Scheme
The clock source bit (CLKSRC) in the CANCTL1 register (12.3.2.2/12-340) defines whether the internal
CANCLK is connected to the output of a crystal oscillator (oscillator clock) or to the bus clock.
The clock source has to be chosen such that the tight oscillator tolerance requirements (up to 0.4%) of the
CAN protocol are met. Additionally, for high CAN bus rates (1 Mbps), a 45% to 55% duty cycle of the
clock is required.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
375
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
If the bus clock is generated from a PLL, it is recommended to select the oscillator clock rather than the
bus clock due to jitter considerations, especially at the faster CAN bus rates.
For microcontrollers without a clock and reset generator (CRG), CANCLK is driven from the crystal
oscillator (oscillator clock).
A programmable prescaler generates the time quanta (Tq) clock from CANCLK. A time quantum is the
atomic unit of time handled by the MSCAN.
Eqn. 12-2
f CANCLK
=
----------------------------------------------------Tq ( Prescaler value -)
A bit time is subdivided into three segments as described in the Bosch CAN specification. (see
Figure 12-41):
• SYNC_SEG: This segment has a fixed length of one time quantum. Signal edges are expected to
happen within this section.
• Time Segment 1: This segment includes the PROP_SEG and the PHASE_SEG1 of the CAN
standard. It can be programmed by setting the parameter TSEG1 to consist of 4 to 16 time quanta.
• Time Segment 2: This segment represents the PHASE_SEG2 of the CAN standard. It can be
programmed by setting the TSEG2 parameter to be 2 to 8 time quanta long.
Eqn. 12-3
f Tq
Bit Rate = --------------------------------------------------------------------------------( number of Time Quanta )
NRZ Signal
SYNC_SEG
Time Segment 1
(PROP_SEG + PHASE_SEG1)
Time Segment 2
(PHASE_SEG2)
1
4 ... 16
2 ... 8
8 ... 25 Time Quanta
= 1 Bit Time
Transmit Point
Sample Point
(single or triple sampling)
Figure 12-41. Segments within the Bit Time
MC9S12HZ256 Data Sheet, Rev. 2.04
376
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-35. Time Segment Syntax
Syntax
Description
System expects transitions to occur on the CAN bus during this
period.
SYNC_SEG
Transmit Point
A node in transmit mode transfers a new value to the CAN bus at
this point.
Sample Point
A node in receive mode samples the CAN bus at this point. If the
three samples per bit option is selected, then this point marks the
position of the third sample.
The synchronization jump width (see the Bosch CAN specification for details) can be programmed in a
range of 1 to 4 time quanta by setting the SJW parameter.
The SYNC_SEG, TSEG1, TSEG2, and SJW parameters are set by programming the MSCAN bus timing
registers (CANBTR0, CANBTR1) (see Section 12.3.2.3, “MSCAN Bus Timing Register 0 (CANBTR0)”
and Section 12.3.2.4, “MSCAN Bus Timing Register 1 (CANBTR1)”).
Table 12-36 gives an overview of the CAN compliant segment settings and the related parameter values.
NOTE
It is the user’s responsibility to ensure the bit time settings are in compliance
with the CAN standard.
Table 12-36. CAN Standard Compliant Bit Time Segment Settings
12.4.4
Synchronization
Jump Width
Time Segment 1
TSEG1
Time Segment 2
TSEG2
SJW
5 .. 10
4 .. 9
2
1
1 .. 2
0 .. 1
4 .. 11
3 .. 10
3
2
1 .. 3
0 .. 2
5 .. 12
4 .. 11
4
3
1 .. 4
0 .. 3
6 .. 13
5 .. 12
5
4
1 .. 4
0 .. 3
7 .. 14
6 .. 13
6
5
1 .. 4
0 .. 3
8 .. 15
7 .. 14
7
6
1 .. 4
0 .. 3
9 .. 16
8 .. 15
8
7
1 .. 4
0 .. 3
Timer Link
The MSCAN generates an internal time stamp whenever a valid frame is received or transmitted and the
TIME bit is enabled. Because the CAN specification defines a frame to be valid if no errors occur before
the end of frame (EOF) field is transmitted successfully, the actual value of an internal timer is written at
EOF to the appropriate time stamp position within the transmit buffer. For receive frames, the time stamp
is written to the receive buffer.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
377
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.5
12.4.5.1
Modes of Operation
Normal Modes
The MSCAN module behaves as described within this specification in all normal system operation modes.
12.4.5.2
Special Modes
The MSCAN module behaves as described within this specification in all special system operation modes.
12.4.5.3
Emulation Modes
In all emulation modes, the MSCAN module behaves just like normal system operation modes as
described within this specification.
12.4.5.4
Listen-Only Mode
In an optional CAN bus monitoring mode (listen-only), the CAN node is able to receive valid data frames
and valid remote frames, but it sends only “recessive” bits on the CAN bus. In addition, it cannot start a
transmision. If the MAC sub-layer is required to send a “dominant” bit (ACK bit, overload flag, or active
error flag), the bit is rerouted internally so that the MAC sub-layer monitors this “dominant” bit, although
the CAN bus may remain in recessive state externally.
12.4.5.5
Security Modes
The MSCAN module has no security features.
12.4.6
Low-Power Options
If the MSCAN is disabled (CANE = 0), the MSCAN clocks are stopped for power saving.
If the MSCAN is enabled (CANE = 1), the MSCAN has two additional modes with reduced power
consumption, compared to normal mode: sleep and power down mode. In sleep mode, power consumption
is reduced by stopping all clocks except those to access the registers from the CPU side. In power down
mode, all clocks are stopped and no power is consumed.
Table 12-37 summarizes the combinations of MSCAN and CPU modes. A particular combination of
modes is entered by the given settings on the CSWAI and SLPRQ/SLPAK bits.
For all modes, an MSCAN wake-up interrupt can occur only if the MSCAN is in sleep mode (SLPRQ = 1
and SLPAK = 1), wake-up functionality is enabled (WUPE = 1), and the wake-up interrupt is enabled
(WUPIE = 1).
MC9S12HZ256 Data Sheet, Rev. 2.04
378
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Table 12-37. CPU vs. MSCAN Operating Modes
MSCAN Mode
Reduced Power Consumption
CPU Mode
Normal
Sleep
RUN
CSWAI = X1
SLPRQ = 0
SLPAK = 0
CSWAI = X
SLPRQ = 1
SLPAK = 1
WAIT
CSWAI = 0
SLPRQ = 0
SLPAK = 0
CSWAI = 0
SLPRQ = 1
SLPAK = 1
STOP
1
Power Down
Disabled
(CANE=0)
CSWAI = X
SLPRQ = X
SLPAK = X
CSWAI = 1
SLPRQ = X
SLPAK = X
CSWAI = X
SLPRQ = X
SLPAK = X
CSWAI = X
SLPRQ = X
SLPAK = X
CSWAI = X
SLPRQ = X
SLPAK = X
‘X’ means don’t care.
12.4.6.1
Operation in Run Mode
As shown in Table 12-37, only MSCAN sleep mode is available as low power option when the CPU is in
run mode.
12.4.6.2
Operation in Wait Mode
The WAI instruction puts the MCU in a low power consumption stand-by mode. If the CSWAI bit is set,
additional power can be saved in power down mode because the CPU clocks are stopped. After leaving
this power down mode, the MSCAN restarts its internal controllers and enters normal mode again.
While the CPU is in wait mode, the MSCAN can be operated in normal mode and generate interrupts
(registers can be accessed via background debug mode). The MSCAN can also operate in any of the
low-power modes depending on the values of the SLPRQ/SLPAK and CSWAI bits as seen in Table 12-37.
12.4.6.3
Operation in Stop Mode
The STOP instruction puts the MCU in a low power consumption stand-by mode. In stop mode, the
MSCAN is set in power down mode regardless of the value of the SLPRQ/SLPAK and CSWAI bits
Table 12-37.
12.4.6.4
MSCAN Sleep Mode
The CPU can request the MSCAN to enter this low power mode by asserting the SLPRQ bit in the
CANCTL0 register. The time when the MSCAN enters sleep mode depends on a fixed synchronization
delay and its current activity:
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
379
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
•
•
•
If there are one or more message buffers scheduled for transmission (TXEx = 0), the MSCAN will
continue to transmit until all transmit message buffers are empty (TXEx = 1, transmitted
successfully or aborted) and then goes into sleep mode.
If the MSCAN is receiving, it continues to receive and goes into sleep mode as soon as the CAN
bus next becomes idle.
If the MSCAN is neither transmitting nor receiving, it immediately goes into sleep mode.
Bus Clock Domain
CAN Clock Domain
SLPRQ
SYNC
sync.
SLPRQ
sync.
SYNC
SLPAK
CPU
Sleep Request
SLPAK
Flag
SLPAK
SLPRQ
Flag
MSCAN
in Sleep Mode
Figure 12-42. Sleep Request / Acknowledge Cycle
NOTE
The application software must avoid setting up a transmission (by clearing
one or more TXEx flag(s)) and immediately request sleep mode (by setting
SLPRQ). Whether the MSCAN starts transmitting or goes into sleep mode
directly depends on the exact sequence of operations.
If sleep mode is active, the SLPRQ and SLPAK bits are set (Figure 12-42). The application software must
use SLPAK as a handshake indication for the request (SLPRQ) to go into sleep mode.
When in sleep mode (SLPRQ = 1 and SLPAK = 1), the MSCAN stops its internal clocks. However, clocks
that allow register accesses from the CPU side continue to run.
If the MSCAN is in bus-off state, it stops counting the 128 occurrences of 11 consecutive recessive bits
due to the stopped clocks. The TXCAN pin remains in a recessive state. If RXF = 1, the message can be
read and RXF can be cleared. Shifting a new message into the foreground buffer of the receiver FIFO
(RxFG) does not take place while in sleep mode.
It is possible to access the transmit buffers and to clear the associated TXE flags. No message abort takes
place while in sleep mode.
If the WUPE bit in CANCLT0 is not asserted, the MSCAN will mask any activity it detects on CAN. The
RXCAN pin is therefore held internally in a recessive state. This locks the MSCAN in sleep mode
(Figure 12-43).
MC9S12HZ256 Data Sheet, Rev. 2.04
380
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
The MSCAN is able to leave sleep mode (wake up) only when:
• CAN bus activity occurs and WUPE = 1
or
• the CPU clears the SLPRQ bit
NOTE
The CPU cannot clear the SLPRQ bit before sleep mode (SLPRQ = 1 and
SLPAK = 1) is active.
After wake-up, the MSCAN waits for 11 consecutive recessive bits to synchronize to the CAN bus. As a
consequence, if the MSCAN is woken-up by a CAN frame, this frame is not received.
The receive message buffers (RxFG and RxBG) contain messages if they were received before sleep mode
was entered. All pending actions will be executed upon wake-up; copying of RxBG into RxFG, message
aborts and message transmissions. If the MSCAN remains in bus-off state after sleep mode was exited, it
continues counting the 128 occurrences of 11 consecutive recessive bits.
CAN Activity
(CAN Activity & WUPE) | SLPRQ
Wait
for Idle
StartUp
CAN Activity
SLPRQ
CAN Activity &
SLPRQ
Sleep
Idle
(CAN Activity & WUPE) |
CAN Activity
CAN Activity &
SLPRQ
CAN Activity
Tx/Rx
Message
Active
CAN Activity
Figure 12-43. Simplified State Transitions for Entering/Leaving Sleep Mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
381
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.6.5
MSCAN Initialization Mode
In initialization mode, any on-going transmission or reception is immediately aborted and synchronization
to the CAN bus is lost, potentially causing CAN protocol violations. To protect the CAN bus system from
fatal consequences of violations, the MSCAN immediately drives the TXCAN pin into a recessive state.
NOTE
The user is responsible for ensuring that the MSCAN is not active when
initialization mode is entered. The recommended procedure is to bring the
MSCAN into sleep mode (SLPRQ = 1 and SLPAK = 1) before setting the
INITRQ bit in the CANCTL0 register. Otherwise, the abort of an on-going
message can cause an error condition and can impact other CAN bus
devices.
In initialization mode, the MSCAN is stopped. However, interface registers remain accessible. This mode
is used to reset the CANCTL0, CANRFLG, CANRIER, CANTFLG, CANTIER, CANTARQ,
CANTAAK, and CANTBSEL registers to their default values. In addition, the MSCAN enables the
configuration of the CANBTR0, CANBTR1 bit timing registers; CANIDAC; and the CANIDAR,
CANIDMR message filters. See Section 12.3.2.1, “MSCAN Control Register 0 (CANCTL0),” for a
detailed description of the initialization mode.
Bus Clock Domain
CAN Clock Domain
INITRQ
SYNC
sync.
INITRQ
sync.
SYNC
INITAK
CPU
Init Request
INITAK
Flag
INITAK
INIT
Flag
Figure 12-44. Initialization Request/Acknowledge Cycle
Due to independent clock domains within the MSCAN, INITRQ must be synchronized to all domains by
using a special handshake mechanism. This handshake causes additional synchronization delay (see
Section Figure 12-44., “Initialization Request/Acknowledge Cycle”).
If there is no message transfer ongoing on the CAN bus, the minimum delay will be two additional bus
clocks and three additional CAN clocks. When all parts of the MSCAN are in initialization mode, the
INITAK flag is set. The application software must use INITAK as a handshake indication for the request
(INITRQ) to go into initialization mode.
NOTE
The CPU cannot clear INITRQ before initialization mode (INITRQ = 1 and
INITAK = 1) is active.
MC9S12HZ256 Data Sheet, Rev. 2.04
382
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.6.6
MSCAN Power Down Mode
The MSCAN is in power down mode (Table 12-37) when
• CPU is in stop mode
or
• CPU is in wait mode and the CSWAI bit is set
When entering the power down mode, the MSCAN immediately stops all ongoing transmissions and
receptions, potentially causing CAN protocol violations. To protect the CAN bus system from fatal
consequences of violations to the above rule, the MSCAN immediately drives the TXCAN pin into a
recessive state.
NOTE
The user is responsible for ensuring that the MSCAN is not active when
power down mode is entered. The recommended procedure is to bring the
MSCAN into Sleep mode before the STOP or WAI instruction (if CSWAI
is set) is executed. Otherwise, the abort of an ongoing message can cause an
error condition and impact other CAN bus devices.
In power down mode, all clocks are stopped and no registers can be accessed. If the MSCAN was not in
sleep mode before power down mode became active, the module performs an internal recovery cycle after
powering up. This causes some fixed delay before the module enters normal mode again.
12.4.6.7
Programmable Wake-Up Function
The MSCAN can be programmed to wake up the MSCAN as soon as CAN bus activity is detected (see
control bit WUPE in Section 12.3.2.1, “MSCAN Control Register 0 (CANCTL0)”). The sensitivity to
existing CAN bus action can be modified by applying a low-pass filter function to the RXCAN input line
while in sleep mode (see control bit WUPM in Section 12.3.2.2, “MSCAN Control Register 1
(CANCTL1)”).
This feature can be used to protect the MSCAN from wake-up due to short glitches on the CAN bus lines.
Such glitches can result from—for example—electromagnetic interference within noisy environments.
12.4.7
Reset Initialization
The reset state of each individual bit is listed in Section 12.3.2, “Register Descriptions,” which details all
the registers and their bit-fields.
12.4.8
Interrupts
This section describes all interrupts originated by the MSCAN. It documents the enable bits and generated
flags. Each interrupt is listed and described separately.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
383
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
12.4.8.1
Description of Interrupt Operation
The MSCAN supports four interrupt vectors (see Table 12-38), any of which can be individually masked
(for details see sections from Section 12.3.2.6, “MSCAN Receiver Interrupt Enable Register
(CANRIER),” to Section 12.3.2.8, “MSCAN Transmitter Interrupt Enable Register (CANTIER)”).
NOTE
The dedicated interrupt vector addresses are defined in the Resets and
Interrupts chapter.
Table 12-38. Interrupt Vectors
Interrupt Source
Wake-Up Interrupt (WUPIF)
12.4.8.2
CCR Mask
I bit
Local Enable
CANRIER (WUPIE)
Error Interrupts Interrupt (CSCIF, OVRIF)
I bit
CANRIER (CSCIE, OVRIE)
Receive Interrupt (RXF)
I bit
CANRIER (RXFIE)
Transmit Interrupts (TXE[2:0])
I bit
CANTIER (TXEIE[2:0])
Transmit Interrupt
At least one of the three transmit buffers is empty (not scheduled) and can be loaded to schedule a message
for transmission. The TXEx flag of the empty message buffer is set.
12.4.8.3
Receive Interrupt
A message is successfully received and shifted into the foreground buffer (RxFG) of the receiver FIFO.
This interrupt is generated immediately after receiving the EOF symbol. The RXF flag is set. If there are
multiple messages in the receiver FIFO, the RXF flag is set as soon as the next message is shifted to the
foreground buffer.
12.4.8.4
Wake-Up Interrupt
A wake-up interrupt is generated if activity on the CAN bus occurs during MSCN internal sleep mode.
WUPE (see Section 12.3.2.1, “MSCAN Control Register 0 (CANCTL0)”) must be enabled.
12.4.8.5
Error Interrupt
An error interrupt is generated if an overrun of the receiver FIFO, error, warning, or bus-off condition
occurrs. Section 12.3.2.5, “MSCAN Receiver Flag Register (CANRFLG) indicates one of the following
conditions:
• Overrun — An overrun condition of the receiver FIFO as described in Section 12.4.2.3, “Receive
Structures,” occurred.
• CAN Status Change — The actual value of the transmit and receive error counters control the
CAN bus state of the MSCAN. As soon as the error counters skip into a critical range
(Tx/Rx-warning, Tx/Rx-error, bus-off) the MSCAN flags an error condition. The status change,
which caused the error condition, is indicated by the TSTAT and RSTAT flags (see
MC9S12HZ256 Data Sheet, Rev. 2.04
384
Freescale Semiconductor
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
Section 12.3.2.5, “MSCAN Receiver Flag Register (CANRFLG)” and Section 12.3.2.6, “MSCAN
Receiver Interrupt Enable Register (CANRIER)”).
12.4.8.6
Interrupt Acknowledge
Interrupts are directly associated with one or more status flags in either the Section 12.3.2.5, “MSCAN
Receiver Flag Register (CANRFLG)” or the Section 12.3.2.7, “MSCAN Transmitter Flag Register
(CANTFLG).” Interrupts are pending as long as one of the corresponding flags is set. The flags in
CANRFLG and CANTFLG must be reset within the interrupt handler to handshake the interrupt. The flags
are reset by writing a 1 to the corresponding bit position. A flag cannot be cleared if the respective
condition prevails.
NOTE
It must be guaranteed that the CPU clears only the bit causing the current
interrupt. For this reason, bit manipulation instructions (BSET) must not be
used to clear interrupt flags. These instructions may cause accidental
clearing of interrupt flags which are set after entering the current interrupt
service routine.
12.4.8.7
Recovery from Stop or Wait
The MSCAN can recover from stop or wait via the wake-up interrupt. This interrupt can only occur if the
MSCAN was in sleep mode (SLPRQ = 1 and SLPAK = 1) before entering power down mode, the wake-up
option is enabled (WUPE = 1), and the wake-up interrupt is enabled (WUPIE = 1).
12.5
12.5.1
Initialization/Application Information
MSCAN initialization
The procedure to initially start up the MSCAN module out of reset is as follows:
1. Assert CANE
2. Write to the configuration registers in initialization mode
3. Clear INITRQ to leave initialization mode and enter normal mode
If the configuration of registers which are writable in initialization mode needs to be changed only when
the MSCAN module is in normal mode:
1. Bring the module into sleep mode by setting SLPRQ and awaiting SLPAK to assert after the CAN
bus becomes idle.
2. Enter initialization mode: assert INITRQ and await INITAK
3. Write to the configuration registers in initialization mode
4. Clear INITRQ to leave initialization mode and continue in normal mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
385
Chapter 12 Freescale’s Scalable Controller Area Network (MSCANV2)
MC9S12HZ256 Data Sheet, Rev. 2.04
386
Freescale Semiconductor
Chapter 13
Serial Communication Interface (SCIV4)
13.1
Introduction
This block description chapter provides an overview of serial communication interface (SCI) module.
The SCI allows full duplex, asynchronous, serial communication between the CPU and remote devices,
including other CPUs. The SCI transmitter and receiver operate independently, although they use the same
baud rate generator. The CPU monitors the status of the SCI, writes the data to be transmitted, and
processes received data.
13.1.1
Glossary
IR: infrared
IrDA: Infrared Design Association
IRQ: interrupt request
LSB: least significant bit
MSB: most significant bit
NRZ: non-return-to-Zero
RZI: return-to-zero-inverted
RXD: receive pin
SCI: serial communication interface
TXD: transmit pin
13.1.2
Features
The SCI includes these distinctive features:
• Full-duplex or single-wire operation
• Standard mark/space non-return-to-zero (NRZ) format
• Selectable IrDA 1.4 return-to-zero-inverted (RZI) format with programmable pulse widths
• 13-bit baud rate selection
• Programmable 8-bit or 9-bit data format
• Separately enabled transmitter and receiver
• Programmable polarity for transmitter and receiver
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
387
Chapter 13 Serial Communication Interface (SCIV4)
•
•
•
•
•
•
Programmable transmitter output parity
Two receiver wakeup methods:
— Idle line wakeup
— Address mark wakeup
Interrupt-driven operation with eight flags:
— Transmitter empty
— Transmission complete
— Receiver full
— Idle receiver input
— Receiver overrun
— Noise error
— Framing error
— Parity error
Receiver framing error detection
Hardware parity checking
1/16 bit-time noise detection
13.1.3
Modes of Operation
The SCI functions the same in normal, special, and emulation modes. It has two low-power modes, wait
and stop modes.
13.1.3.1
Run Mode
Normal mode of operation.
13.1.3.2
Wait Mode
SCI operation in wait mode depends on the state of the SCISWAI bit in the SCI control register 1
(SCICR1).
• If SCISWAI is clear, the SCI operates normally when the CPU is in wait mode.
• If SCISWAI is set, SCI clock generation ceases and the SCI module enters a power-conservation
state when the CPU is in wait mode. Setting SCISWAI does not affect the state of the receiver
enable bit, RE, or the transmitter enable bit, TE.
If SCISWAI is set, any transmission or reception in progress stops at wait mode entry. The
transmission or reception resumes when either an internal or external interrupt brings the CPU out
of wait mode. Exiting wait mode by reset aborts any transmission or reception in progress and
resets the SCI.
MC9S12HZ256 Data Sheet, Rev. 2.04
388
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.1.3.3
Stop Mode
The SCI is inactive during stop mode for reduced power consumption. The STOP instruction does not
affect the SCI register states, but the SCI bus clock will be disabled. The SCI operation resumes after an
external interrupt brings the CPU out of stop mode. Exiting stop mode by reset aborts any transmission or
reception in progress and resets the SCI.
13.1.4
Block Diagram
Figure 13-1 is a high level block diagram of the SCI module, showing the interaction of various function
blocks.
SCI Data Register
IDLE Interrupt Request
RXD
Data In
Infrared
Decoder
Receive Shift Register
IRQ
Generation
Receive & Wakeup Control
Bus Clk
BAUD
Generator
÷16
RDRF/OR
Interrupt
Request
Data Format Control
TDRE
Interrupt
Request
SCI
Interrupt
Request
Transmit Control
Transmit Shift Register
IRQ
Generation
TC Interrupt Request
SCI Data Register
Infrared
Data Out
TXD
Encoder
Figure 13-1. SCI Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
389
Chapter 13 Serial Communication Interface (SCIV4)
13.2
External Signal Descriptions
The SCI module has a total of two external pins.
13.2.1
TXD — SCI Transmit Pin
The TXD pin transmits SCI (standard or infrared) data. It will idle high in either mode and is high
impedance anytime the transmitter is disabled.
13.2.2
RXD — SCI Receive Pin
The RXD pin receives SCI (standard or infrared) data. An idle line is detected as a line high. This input is
ignored when the receiver is disabled and should be terminated to a known voltage.
13.3
Memory Map and Register Definition
This subsection provides a detailed description of all the SCI registers.
13.3.1
Module Memory Map
The memory map for the SCI module is given in Figure 13-2. The address listed for each register is the
address offset. The total address for each register is the sum of the base address for the SCI module and
the address offset for each register.
13.3.2
Register Descriptions
This subsection consists of register descriptions in address order. Each description includes a standard
register diagram with an associated figure number. Writes to reserved register locations do not have any
effect and reads of these locations return a 0. Details of register bit and field function follow the register
diagrams, in bit order.
Register
Name
SCIBDH
Bit 7
6
5
4
3
2
1
Bit 0
IREN
TNP1
TNP0
SBR12
SBR11
SBR10
SBR9
SBR8
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
R
W
SCIBDL
R
W
SCICR1
R
W
= Unimplemented or Reserved
Figure 13-2. SCI Registers Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
390
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
Register
Name
SCICR2
Bit 7
6
5
4
3
2
1
Bit 0
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
0
0
0
TXPOL
RXPOL
BRK13
TXDIR
0
0
0
0
0
0
R
W
SCISR1
R
W
SCISR2
R
RAF
W
SCIDRH
R
R8
T8
W
SCIDRL
R
R7
R6
R5
R4
R3
R2
R1
R0
W
T7
T6
T5
T4
T3
T2
T1
T0
= Unimplemented or Reserved
Figure 13-2. SCI Registers Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
391
Chapter 13 Serial Communication Interface (SCIV4)
13.3.2.1
SCI Baud Rate Registers (SCIBDH and SCIBDL)
7
6
5
4
3
2
1
0
IREN
TNP1
TNP0
SBR12
SBR11
SBR10
SBR9
SBR8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 13-3. SCI Baud Rate Register High (SCIBDH)
Table 13-1. SCIBDH Field Descriptions
Field
7
IREN
6:5
TNP[1:0]
4:0
SBR[11:8]
Description
Infrared Enable Bit — This bit enables/disables the infrared modulation/demodulation submodule.
0 IR disabled
1 IR enabled
Transmitter Narrow Pulse Bits — These bits determine if the SCI will transmit a 1/16, 3/16, 1/32, or 1/4 narrow
pulse. Refer to Table 13-3.
SCI Baud Rate Bits — The baud rate for the SCI is determined by the bits in this register. The baud rate is
calculated two different ways depending on the state of the IREN bit.
The formulas for calculating the baud rate are:
When IREN = 0 then,
SCI baud rate = SCI module clock / (16 x SBR[12:0])
When IREN = 1 then,
SCI baud rate = SCI module clock / (32 x SBR[12:1])
7
6
5
4
3
2
1
0
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
0
0
0
0
0
1
0
0
R
W
Reset
Figure 13-4. SCI Baud Rate Register Low (SCIBDL)
Table 13-2. SCIBDL Field Descriptions
Field
7:0
SBR[7:0]
Description
SCI Baud Rate Bits — The baud rate for the SCI is determined by the bits in this register. The baud rate is
calculated two different ways depending on the state of the IREN bit.
The formulas for calculating the baud rate are:
When IREN = 0 then,
SCI baud rate = SCI module clock / (16 x SBR[12:0])
When IREN = 1 then,
SCI baud rate = SCI module clock / (32 x SBR[12:1])
Read: anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
392
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
NOTE
If only SCIBDH is written to, a read will not return the correct data until
SCIBDL is written to as well, following a write to SCIBDH.
Write: anytime
The SCI baud rate register is used to determine the baud rate of the SCI and to control the infrared
modulation/demodulation submodule.
Table 13-3. IRSCI Transmit Pulse Width
TNP[1:0]
Narrow Pulse Width
11
1/4
10
1/32
01
1/16
00
3/16
NOTE
The baud rate generator is disabled after reset and not started until the TE
bit or the RE bit is set for the first time. The baud rate generator is disabled
when (SBR[12:0] = 0 and IREN = 0) or (SBR[12:1] = 0 and IREN = 1).
Writing to SCIBDH has no effect without writing to SCIBDL, because
writing to SCIBDH puts the data in a temporary location until SCIBDL is
written to.
13.3.2.2
SCI Control Register 1 (SCICR1)
7
6
5
4
3
2
1
0
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
0
0
0
0
0
0
0
0
R
W
Reset
Figure 13-5. SCI Control Register 1 (SCICR1)
Read: anytime
Write: anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
393
Chapter 13 Serial Communication Interface (SCIV4)
Table 13-4. SCICR1 Field Descriptions
Field
Description
7
LOOPS
Loop Select Bit — LOOPS enables loop operation. In loop operation, the RXD pin is disconnected from the SCI
and the transmitter output is internally connected to the receiver input. Both the transmitter and the receiver must
be enabled to use the loop function.
0 Normal operation enabled
1 Loop operation enabled
The receiver input is determined by the RSRC bit.
6
SCISWAI
5
RSRC
4
M
SCI Stop in Wait Mode Bit — SCISWAI disables the SCI in wait mode.
0 SCI enabled in wait mode
1 SCI disabled in wait mode
Receiver Source Bit — When LOOPS = 1, the RSRC bit determines the source for the receiver shift register
input.
0 Receiver input internally connected to transmitter output
1 Receiver input connected externally to transmitter
Refer to Table 13-5.
Data Format Mode Bit — MODE determines whether data characters are eight or nine bits long.
0 One start bit, eight data bits, one stop bit
1 One start bit, nine data bits, one stop bit
3
WAKE
Wakeup Condition Bit — WAKE determines which condition wakes up the SCI: a logic 1 (address mark) in the
most significant bit position of a received data character or an idle condition on the RXD pin.
0 Idle line wakeup
1 Address mark wakeup
2
ILT
Idle Line Type Bit — ILT determines when the receiver starts counting logic 1s as idle character bits. The
counting begins either after the start bit or after the stop bit. If the count begins after the start bit, then a string of
logic 1s preceding the stop bit may cause false recognition of an idle character. Beginning the count after the
stop bit avoids false idle character recognition, but requires properly synchronized transmissions.
0 Idle character bit count begins after start bit
1 Idle character bit count begins after stop bit
1
PE
Parity Enable Bit — PE enables the parity function. When enabled, the parity function inserts a parity bit in the
most significant bit position.
0 Parity function disabled
1 Parity function enabled
0
PT
Parity Type Bit — PT determines whether the SCI generates and checks for even parity or odd parity. With even
parity, an even number of 1s clears the parity bit and an odd number of 1s sets the parity bit. With odd parity, an
odd number of 1s clears the parity bit and an even number of 1s sets the parity bit.
0 Even parity
1 Odd parity
Table 13-5. Loop Functions
LOOPS
RSRC
Function
0
x
Normal operation
1
0
Loop mode with transmitter output internally connected to receiver input
1
1
Single-wire mode with TXD pin connected to receiver input
MC9S12HZ256 Data Sheet, Rev. 2.04
394
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.3.2.3
SCI Control Register 2 (SCICR2)
7
6
5
4
3
2
1
0
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
0
R
W
Reset
Figure 13-6. SCI Control Register 2 (SCICR2)
Read: anytime
Write: anytime
Table 13-6. SCICR2 Field Descriptions
Field
7
TIE
Description
Transmitter Interrupt Enable Bit —TIE enables the transmit data register empty flag, TDRE, to generate
interrupt requests.
0 TDRE interrupt requests disabled
1 TDRE interrupt requests enabled
6
TCIE
Transmission Complete Interrupt Enable Bit — TCIE enables the transmission complete flag, TC, to generate
interrupt requests.
0 TC interrupt requests disabled
1 TC interrupt requests enabled
5
RIE
Receiver Full Interrupt Enable Bit — RIE enables the receive data register full flag, RDRF, or the overrun flag,
OR, to generate interrupt requests.
0 RDRF and OR interrupt requests disabled
1 RDRF and OR interrupt requests enabled
4
ILIE
Idle Line Interrupt Enable Bit — ILIE enables the idle line flag, IDLE, to generate interrupt requests.
0 IDLE interrupt requests disabled
1 IDLE interrupt requests enabled
3
TE
Transmitter Enable Bit — TE enables the SCI transmitter and configures the TXD pin as being controlled by
the SCI. The TE bit can be used to queue an idle preamble.
0 Transmitter disabled
1 Transmitter enabled
2
RE
Receiver Enable Bit — RE enables the SCI receiver.
0 Receiver disabled
1 Receiver enabled
1
RWU
Receiver Wakeup Bit — Standby state
0 Normal operation.
1 RWU enables the wakeup function and inhibits further receiver interrupt requests. Normally, hardware wakes
the receiver by automatically clearing RWU.
0
SBK
Send Break Bit — Toggling SBK sends one break character (10 or 11 logic 0s, respectively 13 or 14 logics 0s
if BRK13 is set). Toggling implies clearing the SBK bit before the break character has finished transmitting. As
long as SBK is set, the transmitter continues to send complete break characters (10 or 11 bits, respectively 13
or 14 bits).
0 No break characters
1 Transmit break characters
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
395
Chapter 13 Serial Communication Interface (SCIV4)
13.3.2.4
SCI Status Register 1 (SCISR1)
The SCISR1 and SCISR2 registers provide inputs to the MCU for generation of SCI interrupts. Also, these
registers can be polled by the MCU to check the status of these bits. The flag-clearing procedures require
that the status register be read followed by a read or write to the SCI data register. It is permissible to
execute other instructions between the two steps as long as it does not compromise the handling of I/O.
Note that the order of operations is important for flag clearing.
R
7
6
5
4
3
2
1
0
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
1
1
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 13-7. SCI Status Register 1 (SCISR1)
Read: anytime
Write: has no meaning or effect
Table 13-7. SCISR1 Field Descriptions
Field
Description
7
TDRE
Transmit Data Register Empty Flag — TDRE is set when the transmit shift register receives a byte from the
SCI data register. When TDRE is 1, the transmit data register (SCIDRH/L) is empty and can receive a new value
to transmit.Clear TDRE by reading SCI status register 1 (SCISR1), with TDRE set and then writing to SCI data
register low (SCIDRL).
0 No byte transferred to transmit shift register
1 Byte transferred to transmit shift register; transmit data register empty
6
TC
Transmit Complete Flag — TC is set low when there is a transmission in progress or when a preamble or break
character is loaded. TC is set high when the TDRE flag is set and no data, preamble, or break character is being
transmitted.When TC is set, the TXD pin becomes idle (logic 1). Clear TC by reading SCI status register 1
(SCISR1) with TC set and then writing to SCI data register low (SCIDRL). TC is cleared automatically when data,
preamble, or break is queued and ready to be sent. TC is cleared in the event of a simultaneous set and clear of
the TC flag (transmission not complete).
0 Transmission in progress
1 No transmission in progress
5
RDRF
Receive Data Register Full Flag — RDRF is set when the data in the receive shift register transfers to the SCI
data register. Clear RDRF by reading SCI status register 1 (SCISR1) with RDRF set and then reading SCI data
register low (SCIDRL).
0 Data not available in SCI data register
1 Received data available in SCI data register
4
IDLE
Idle Line Flag1 — IDLE is set when 10 consecutive logic 1s (if M = 0) or 11 consecutive logic 1s (if M = 1) appear
on the receiver input. After the IDLE flag is cleared, a valid frame must again set the RDRF flag before an idle
condition can set the IDLE flag.Clear IDLE by reading SCI status register 1 (SCISR1) with IDLE set and then
reading SCI data register low (SCIDRL).
0 Receiver input is either active now or has never become active since the IDLE flag was last cleared
1 Receiver input has become idle
MC9S12HZ256 Data Sheet, Rev. 2.04
396
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
Table 13-7. SCISR1 Field Descriptions (continued)
1
2
Field
Description
3
OR
Overrun Flag2 — OR is set when software fails to read the SCI data register before the receive shift register
receives the next frame. The OR bit is set immediately after the stop bit has been completely received for the
second frame. The data in the shift register is lost, but the data already in the SCI data registers is not affected.
Clear OR by reading SCI status register 1 (SCISR1) with OR set and then reading SCI data register low
(SCIDRL).
0 No overrun
1 Overrun
2
NF
Noise Flag — NF is set when the SCI detects noise on the receiver input. NF bit is set during the same cycle as
the RDRF flag but does not get set in the case of an overrun. Clear NF by reading SCI status register 1(SCISR1),
and then reading SCI data register low (SCIDRL).
0 No noise
1 Noise
1
FE
Framing Error Flag — FE is set when a logic 0 is accepted as the stop bit. FE bit is set during the same cycle
as the RDRF flag but does not get set in the case of an overrun. FE inhibits further data reception until it is
cleared. Clear FE by reading SCI status register 1 (SCISR1) with FE set and then reading the SCI data register
low (SCIDRL).
0 No framing error
1 Framing error
0
PF
Parity Error Flag — PF is set when the parity enable bit (PE) is set and the parity of the received data does not
match the parity type bit (PT). PF bit is set during the same cycle as the RDRF flag but does not get set in the
case of an overrun. Clear PF by reading SCI status register 1 (SCISR1), and then reading SCI data register low
(SCIDRL).
0 No parity error
1 Parity error
When the receiver wakeup bit (RWU) is set, an idle line condition does not set the IDLE flag.
The OR flag may read back as set when RDRF flag is clear. This may happen if the following sequence of events occurs:
1. After the first frame is received, read status register SCISR1 (returns RDRF set and OR flag clear);
2. Receive second frame without reading the first frame in the data register (the second frame is not received and OR flag
is set);
3. Read data register SCIDRL (returns first frame and clears RDRF flag in the status register);
4. Read status register SCISR1 (returns RDRF clear and OR set).
Event 3 may be at exactly the same time as event 2 or any time after. When this happens, a dummy SCIDRL read following
event 4 will be required to clear the OR flag if further frames are to be received.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
397
Chapter 13 Serial Communication Interface (SCIV4)
13.3.2.5
R
SCI Status Register 2 (SCISR2)
7
6
5
0
0
0
4
3
2
1
TXPOL
RXPOL
BRK13
TXDIR
0
0
0
0
0
RAF
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 13-8. SCI Status Register 2 (SCISR2)
Read: anytime
Write: anytime
Table 13-8. SCISR2 Field Descriptions
Field
Description
4
TXPOL
Transmit Polarity — This bit control the polarity of the transmitted data. In NRZ format, a 1 is represented by a
mark and a 0 is represented by a space for normal polarity, and the opposite for inverted polarity. In IrDA format,
a 0 is represented by short high pulse in the middle of a bit time remaining idle low for a 1 for normal polarity, and
a 0 is represented by short low pulse in the middle of a bit time remaining idle high for a 1 for inverted polarity.
0 Normal polarity
1 Inverted polarity
3
RXPOL
Receive Polarity — This bit control the polarity of the received data. In NRZ format, a 1 is represented by a mark
and a 0 is represented by a space for normal polarity, and the opposite for inverted polarity. In IrDA format, a 0
is represented by short high pulse in the middle of a bit time remaining idle low for a 1 for normal polarity, and a
0 is represented by short low pulse in the middle of a bit time remaining idle high for a 1 for inverted polarity.
0 Normal polarity
1 Inverted polarity
2
BRK13
Break Transmit Character Length — This bit determines whether the transmit break character is 10 or 11 bit
respectively 13 or 14 bits long. The detection of a framing error is not affected by this bit.
0 Break character is 10 or 11 bit long
1 Break character is 13 or 14 bit long
1
TXDIR
Transmitter Pin Data Direction in Single-Wire Mode — This bit determines whether the TXD pin is going to
be used as an input or output, in the single-wire mode of operation. This bit is only relevant in the single-wire
mode of operation.
0 TXD pin to be used as an input in single-wire mode
1 TXD pin to be used as an output in single-wire mode
0
RAF
Receiver Active Flag — RAF is set when the receiver detects a logic 0 during the RT1 time period of the start
bit search. RAF is cleared when the receiver detects an idle character.
0 No reception in progress
1 Reception in progress
MC9S12HZ256 Data Sheet, Rev. 2.04
398
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.3.2.6
SCI Data Registers (SCIDRH and SCIDRL)
7
R
6
R8
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
T8
W
Reset
0
0
= Unimplemented or Reserved
Figure 13-9. SCI Data Register High (SCIDRH)
Table 13-9. SCIDRH Field Descriptions
Field
Description
7
R8
Received Bit 8 — R8 is the ninth data bit received when the SCI is configured for 9-bit data format (M = 1).
6
T8
Transmit Bit 8 — T8 is the ninth data bit transmitted when the SCI is configured for 9-bit data format (M = 1).
7
6
5
4
3
2
1
0
R
R7
R6
R5
R4
R3
R2
R1
R0
W
T7
T6
T5
T4
T3
T2
T1
T0
0
0
0
0
0
0
0
0
Reset
Figure 13-10. SCI Data Register Low (SCIDRL)
Read: anytime; reading accesses SCI receive data register
Write: anytime; writing accesses SCI transmit data register; writing to R8 has no effect
Table 13-10. SCIDRL Field Descriptions
Field
7:0
R[7:0]
T[7:0}
Description
Received bits 7 through 0 — For 9-bit or 8-bit data formats
Transmit bits 7 through 0 — For 9-bit or 8-bit formats
NOTE
If the value of T8 is the same as in the previous transmission, T8 does not
have to be rewritten.The same value is transmitted until T8 is rewritten
In 8-bit data format, only SCI data register low (SCIDRL) needs to be
accessed.
When transmitting in 9-bit data format and using 8-bit write instructions,
write first to SCI data register high (SCIDRH) then to SCIDRL.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
399
Chapter 13 Serial Communication Interface (SCIV4)
13.4
Functional Description
This subsection provides a complete functional description of the SCI block, detailing the operation of the
design from the end user’s perspective in a number of descriptions.
Figure 13-11 shows the structure of the SCI module. The SCI allows full duplex, asynchronous, serial
communication between the CPU and remote devices, including other CPUs. The SCI transmitter and
receiver operate independently, although they use the same baud rate generator. The CPU monitors the
status of the SCI, writes the data to be transmitted, and processes received data.
IREN
SCI DATA
REGISTER
RXD
INFRARED
RECEIVE
DECODER
R8
Ir_RXD
SCRXD
RECEIVE
SHIFT REGISTER
NF
RE
R16XCLK
RECEIVE
AND WAKEUP
CONTROL
RWU
PF
LOOPS
RAF
RSRC
IDLE
ILIE
IDLE
RDRF
M
BAUD RATE
GENERATOR
OR
RDRF/OR
BUS
CLOCK
FE
WAKE
DATA FORMAT
CONTROL
ILT
RIE
PE
SBR12–SBR0
PT
TE
÷16
TRANSMIT
CONTROL
TRANSMIT
SHIFT REGISTER
T8
SCI
Interrupt
Request
TIE
LOOPS
SBK
TDRE
RSRC
TC
TDRE
TC
TCIE
SCTXD
SCI DATA
REGISTER
R16XCLK
INFRARED
TRANSMIT
ENCODER
TXD
Ir_TXD
R32XCLK
TNP[1:0]
IREN
Figure 13-11. Detailed SCI Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
400
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.4.1
Infrared Interface Submodule
This module provides the capability of transmitting narrow pulses to an IR LED and receiving narrow
pulses and transforming them to serial bits, which are sent to the SCI. The IrDA physical layer
specification defines a half-duplex infrared communication link for exchange data. The full standard
includes data rates up to 16 Mbits/s. This design covers only data rates between 2.4 kbits/s and
115.2 kbits/s.
The infrared submodule consists of two major blocks: the transmit encoder and the receive decoder. The
SCI transmits serial bits of data which are encoded by the infrared submodule to transmit a narrow pulse
for every 0 bit. No pulse is transmitted for every 1 bit. When receiving data, the IR pulses should be
detected using an IR photo diode and transformed to CMOS levels by the IR receive decoder (external
from the MCU). The narrow pulses are then stretched by the infrared submodule to get back to a serial bit
stream to be received by the SCI. The polarity of transmitted pulses and expected receive pulses can be
inverted so that a direct connection can be made to external IrDA transceiver modules that uses active low
pulses.
The infrared submodule receives its clock sources from the SCI. One of these two clocks are selected in
the infrared submodule in order to generate either 3/16, 1/16, 1/32, or 1/4 narrow pulses during
transmission. The infrared block receives two clock sources from the SCI, R16XCLK, and R32XCLK,
which are configured to generate the narrow pulse width during transmission. The R16XCLK and
R32XCLK are internal clocks with frequencies 16 and 32 times the baud rate respectively. Both
R16XCLK and R32XCLK clocks are used for transmitting data. The receive decoder uses only the
R16XCLK clock.
13.4.1.1
Infrared Transmit Encoder
The infrared transmit encoder converts serial bits of data from transmit shift register to the TXD pin. A
narrow pulse is transmitted for a 0 bit and no pulse for a 1 bit. The narrow pulse is sent in the middle of
the bit with a duration of 1/32, 1/16, 3/16, or 1/4 of a bit time. A narrow high pulse is transmitted for a 0 bit
when TXPOL is cleared, while a narrow low pulse is transmitted for a 0 bit when TXPOL is set.
13.4.1.2
Infrared Receive Decoder
The infrared receive block converts data from the RXD pin to the receive shift register. A narrow pulse is
expected for each 0 received and no pulse is expected for each 1 received. A narrow high pulse is expected
for a 0 bit when RXPOL is cleared, while a narrow low pulse is expected for a 0 bit when RXPOL is set.
This receive decoder meets the edge jitter requirement as defined by the IrDA serial infrared physical layer
specification.
13.4.2
Data Format
The SCI uses the standard NRZ mark/space data format. When Infrared is enabled, the SCI uses RZI data
format where 0s are represented by light pulses and 1s remain low. See Figure 13-12.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
401
Chapter 13 Serial Communication Interface (SCIV4)
8-BIT DATA FORMAT
(BIT M IN SCICR1 CLEAR)
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
POSSIBLE
PARITY
BIT
BIT 6
BIT 7
NEXT
START
BIT
STOP
BIT
STANDARD
SCI DATA
INFRARED
SCI DATA
9-BIT DATA FORMAT
(BIT M IN SCICR1 SET)
START
BIT
BIT 0
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
POSSIBLE
PARITY
BIT
BIT 6
BIT 7
BIT 8
STOP
BIT
NEXT
START
BIT
STANDARD
SCI DATA
INFRARED
SCI DATA
Figure 13-12. SCI Data Formats
Each data character is contained in a frame that includes a start bit, eight or nine data bits, and a stop bit.
Clearing the M bit in SCI control register 1 configures the SCI for 8-bit data characters. A frame with eight
data bits has a total of 10 bits. Setting the M bit configures the SCI for nine-bit data characters. A frame
with nine data bits has a total of 11 bits
Table 13-11. Example of 8-bit Data Formats
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
1
8
0
0
1
1
7
0
1
1
7
1
0
1
1
1
1
The address bit identifies the frame as an address
character. See Section 13.4.5.6, “Receiver Wakeup”.
When the SCI is configured for 9-bit data characters, the ninth data bit is the T8 bit in SCI data register
high (SCIDRH). It remains unchanged after transmission and can be used repeatedly without rewriting it.
A frame with nine data bits has a total of 11 bits.
Table 13-12. Example of 9-Bit Data Formats
1
Start
Bit
Data
Bits
Address
Bits
Parity
Bits
Stop
Bit
1
9
0
0
1
1
8
0
1
1
1
8
11
0
1
The address bit identifies the frame as an address
character. See Section 13.4.5.6, “Receiver Wakeup”.
MC9S12HZ256 Data Sheet, Rev. 2.04
402
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.4.3
Baud Rate Generation
A 13-bit modulus counter in the baud rate generator derives the baud rate for both the receiver and the
transmitter. The value from 0 to 8191 written to the SBR[12:0] bits determines the module clock divisor.
The SBR bits are in the SCI baud rate registers (SCIBDH and SCIBDL). The baud rate clock is
synchronized with the bus clock and drives the receiver. The baud rate clock divided by 16 drives the
transmitter. The receiver has an acquisition rate of 16 samples per bit time.
Baud rate generation is subject to one source of error:
• Integer division of the module clock may not give the exact target frequency.
Table 13-13 lists some examples of achieving target baud rates with a module clock frequency of 10.2
MHz.
When IREN = 0 then,
SCI baud rate = SCI module clock / (16 * SCIBR[12:0])
Table 13-13. Baud Rates (Example: Module Clock = 10.2 MHz)
Bits
SBR[12–0]
Receiver
Clock (Hz)
Transmitter
Clock (Hz)
Target Baud
Rate
Error
(%)
17
600,000.0
37,500.0
38,400
2.3
33
309,090.9
19,318.2
19,200
.62
66
154,545.5
9659.1
9600
.62
133
76,691.7
4793.2
4800
.14
266
38,345.9
2396.6
2400
.14
531
19,209.0
1200.6
1200
.11
1062
9604.5
600.3
600
.05
2125
4800.0
300.0
300
.00
4250
2400.0
150.0
150
.00
5795
1760.1
110.0
110
.00
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
403
Chapter 13 Serial Communication Interface (SCIV4)
13.4.4
Transmitter
INTERNAL BUS
÷ 16
BAUD DIVIDER
STOP
SBR12–SBR0
SCI DATA REGISTERS
H
11-BIT TRANSMIT SHIFT REGISTER
8
7
6
5
4
3
2
1
0
TXPOL
SCTXD
L
PT
PARITY
GENERATION
LOOP
CONTROL
BREAK (ALL 0s)
PE
PREAMBLE (ALL ONES)
T8
SHIFT ENABLE
LOAD FROM SCIDR
MSB
M
START
BUS
CLOCK
TO RECEIVER
LOOPS
RSRC
TRANSMITTER CONTROL
TDRE INTERRUPT REQUEST
TC INTERRUPT REQUEST
TDRE
TE
SBK
TIE
TC
TCIE
Figure 13-13. Transmitter Block Diagram
13.4.4.1
Transmitter Character Length
The SCI transmitter can accommodate either 8-bit or 9-bit data characters. The state of the M bit in SCI
control register 1 (SCICR1) determines the length of data characters. When transmitting 9-bit data, bit T8
in SCI data register high (SCIDRH) is the ninth bit (bit 8).
13.4.4.2
Character Transmission
To transmit data, the MCU writes the data bits to the SCI data registers (SCIDRH/SCIDRL), which in turn
are transferred to the transmitter shift register. The transmit shift register then shifts a frame out through
the TXD pin, after it has prefaced them with a start bit and appended them with a stop bit. The SCI data
registers (SCIDRH and SCIDRL) are the write-only buffers between the internal data bus and the transmit
shift register.
The SCI also sets a flag, the transmit data register empty flag (TDRE), every time it transfers data from
the buffer (SCIDRH/L) to the transmitter shift register. The transmit driver routine may respond to this
MC9S12HZ256 Data Sheet, Rev. 2.04
404
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
flag by writing another byte to the transmitter buffer (SCIDRH/SCIDRL), while the shift register is
shifting out the first byte.
To initiate an SCI transmission:
1. Configure the SCI:
a) Select a baud rate. Write this value to the SCI baud registers (SCIBDH/L) to begin the baud
rate generator. Remember that the baud rate generator is disabled when the baud rate is 0.
Writing to the SCIBDH has no effect without also writing to SCIBDL.
b) Write to SCICR1 to configure word length, parity, and other configuration bits (LOOPS,
RSRC, M, WAKE, ILT, PE, and PT).
c) Enable the transmitter, interrupts, receive, and wake up as required, by writing to the SCICR2
register bits (TIE, TCIE, RIE, ILIE, TE, RE, RWU, and SBK). A preamble or idle character
will now be shifted out of the transmitter shift register.
2. Transmit procedure for each byte:
a) Poll the TDRE flag by reading the SCISR1 or responding to the TDRE interrupt. Keep in mind
that the TDRE bit resets to 1.
b) If the TDRE flag is set, write the data to be transmitted to SCIDRH/L, where the ninth bit is
written to the T8 bit in SCIDRH if the SCI is in 9-bit data format. A new transmission will not
result until the TDRE flag has been cleared.
3. Repeat step 2 for each subsequent transmission.
NOTE
The TDRE flag is set when the shift register is loaded with the next data to
be transmitted from SCIDRH/L, which happens, generally speaking, a little
over half-way through the stop bit of the previous frame. Specifically, this
transfer occurs 9/16ths of a bit time AFTER the start of the stop bit of the
previous frame.
Writing the TE bit from 0 to a 1 automatically loads the transmit shift register with a preamble of 10
logic 1s (if M = 0) or 11 logic 1s (if M = 1). After the preamble shifts out, control logic transfers the data
from the SCI data register into the transmit shift register. A logic 0 start bit automatically goes into the
least significant bit position of the transmit shift register. A logic 1 stop bit goes into the most significant
bit position.
Hardware supports odd or even parity. When parity is enabled, the most significant bit (MSB) of the data
character is the parity bit.
The transmit data register empty flag, TDRE, in SCI status register 1 (SCISR1) becomes set when the SCI
data register transfers a byte to the transmit shift register. The TDRE flag indicates that the SCI data
register can accept new data from the internal data bus. If the transmit interrupt enable bit, TIE, in SCI
control register 2 (SCICR2) is also set, the TDRE flag generates a transmitter interrupt request.
When the transmit shift register is not transmitting a frame, the TXD pin goes to the idle condition, logic 1.
If at any time software clears the TE bit in SCI control register 2 (SCICR2), the transmitter enable signal
goes low and the transmit signal goes idle.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
405
Chapter 13 Serial Communication Interface (SCIV4)
If software clears TE while a transmission is in progress (TC = 0), the frame in the transmit shift register
continues to shift out. To avoid accidentally cutting off the last frame in a message, always wait for TDRE
to go high after the last frame before clearing TE.
To separate messages with preambles with minimum idle line time, use this sequence between messages:
1. Write the last byte of the first message to SCIDRH/L.
2. Wait for the TDRE flag to go high, indicating the transfer of the last frame to the transmit shift
register.
3. Queue a preamble by clearing and then setting the TE bit.
4. Write the first byte of the second message to SCIDRH/L.
13.4.4.3
Break Characters
Writing a logic 1 to the send break bit, SBK, in SCI control register 2 (SCICR2) loads the transmit shift
register with a break character. A break character contains all logic 0s and has no start, stop, or parity bit.
Break character length depends on the M bit in SCI control register 1 (SCICR1). As long as SBK is at
logic 1, transmitter logic continuously loads break characters into the transmit shift register. After software
clears the SBK bit, the shift register finishes transmitting the last break character and then transmits at least
one logic 1. The automatic logic 1 at the end of a break character guarantees the recognition of the start bit
of the next frame.
The SCI recognizes a break character when a start bit is followed by eight or nine logic 0 data bits and a
logic 0 where the stop bit should be. Receiving a break character has these effects on SCI registers:
• Sets the framing error flag, FE
• Sets the receive data register full flag, RDRF
• Clears the SCI data registers (SCIDRH/L)
• May set the overrun flag, OR, noise flag, NF, parity error flag, PE, or the receiver active flag, RAF
(see Section 13.3.2.4, “SCI Status Register 1 (SCISR1)” and Section 13.3.2.5, “SCI Status
Register 2 (SCISR2)”).
13.4.4.4
Idle Characters
An idle character (or preamble) contains all logic 1s and has no start, stop, or parity bit. Idle character
length depends on the M bit in SCI control register 1 (SCICR1). The preamble is a synchronizing idle
character that begins the first transmission initiated after writing the TE bit from 0 to 1.
If the TE bit is cleared during a transmission, the TXD pin becomes idle after completion of the
transmission in progress. Clearing and then setting the TE bit during a transmission queues an idle
character to be sent after the frame currently being transmitted.
NOTE
When queueing an idle character, return the TE bit to logic 1 before the stop
bit of the current frame shifts out through the TXD pin. Setting TE after the
stop bit appears on TXD causes data previously written to the SCI data
register to be lost. Toggle the TE bit for a queued idle character while the
MC9S12HZ256 Data Sheet, Rev. 2.04
406
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
TDRE flag is set and immediately before writing the next byte to the SCI
data register.
If the TE bit is clear and the transmission is complete, the SCI is not the
master of the TXD pin
13.4.5
Receiver
INTERNAL BUS
SBR12–SBR0
DATA
RECOVERY
SCRXD
LOOP
CONTROL
FROM TXD PIN
OR TRANSMITTER
H
RE
8
7
6
5
4
3
2
1
0
START
11-BIT RECEIVE SHIFT REGISTER
L
MSB
RXPOL
STOP
BAUD
DIVIDER
ALL ONES
BUS
CLOCK
SCI DATA REGISTER
RAF
LOOPS
RSRC
FE
M
WAKE
ILT
PE
PT
NF
WAKEUP
LOGIC
PE
R8
PARITY
CHECKING
IDLE INTERRUPT REQUEST
RWU
IDLE
ILIE
RDRF
RDRF/OR INTERRUPT REQUEST
RIE
OR
Figure 13-14. SCI Receiver Block Diagram
13.4.5.1
Receiver Character Length
The SCI receiver can accommodate either 8-bit or 9-bit data characters. The state of the M bit in SCI
control register 1 (SCICR1) determines the length of data characters. When receiving 9-bit data, bit R8 in
SCI data register high (SCIDRH) is the ninth bit (bit 8).
13.4.5.2
Character Reception
During an SCI reception, the receive shift register shifts a frame in from the RXD pin. The SCI data
register is the read-only buffer between the internal data bus and the receive shift register.
After a complete frame shifts into the receive shift register, the data portion of the frame transfers to the
SCI data register. The receive data register full flag, RDRF, in SCI status register 1 (SCISR1) becomes set,
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
407
Chapter 13 Serial Communication Interface (SCIV4)
indicating that the received byte can be read. If the receive interrupt enable bit, RIE, in SCI control register
2 (SCICR2) is also set, the RDRF flag generates an RDRF interrupt request.
13.4.5.3
Data Sampling
The receiver samples the RXD pin at the RT clock rate. The RT clock is an internal signal with a frequency
16 times the baud rate. To adjust for baud rate mismatch, the RT clock (see Figure 13-15) is
re-synchronized:
• After every start bit
• After the receiver detects a data bit change from logic 1 to logic 0 (after the majority of data bit
samples at RT8, RT9, and RT10 returns a valid logic 1 and the majority of the next RT8, RT9, and
RT10 samples returns a valid logic 0)
To locate the start bit, data recovery logic does an asynchronous search for a logic 0 preceded by three
logic 1s. When the falling edge of a possible start bit occurs, the RT clock begins to count to 16.
START BIT
LSB
RXD
SAMPLES
1
1
1
1
1
1
1
1
0
0
START BIT
QUALIFICATION
0
0
START BIT
VERIFICATION
0
0
0
DATA
SAMPLING
RT4
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
RT3
RT2
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT CLOCK COUNT
RT1
RT CLOCK
RESET RT CLOCK
Figure 13-15. Receiver Data Sampling
To verify the start bit and to detect noise, data recovery logic takes samples at RT3, RT5, and RT7.
Table 13-14 summarizes the results of the start bit verification samples.
Table 13-14. Start Bit Verification
RT3, RT5, and RT7 Samples
Start Bit Verification
Noise Flag
000
Yes
0
001
Yes
1
010
Yes
1
011
No
0
100
Yes
1
101
No
0
110
No
0
111
No
0
If start bit verification is not successful, the RT clock is reset and a new search for a start bit begins.
MC9S12HZ256 Data Sheet, Rev. 2.04
408
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
To determine the value of a data bit and to detect noise, recovery logic takes samples at RT8, RT9, and
RT10. Table 13-15 summarizes the results of the data bit samples.
Table 13-15. Data Bit Recovery
RT8, RT9, and RT10 Samples
Data Bit Determination
Noise Flag
000
0
0
001
0
1
010
0
1
011
1
1
100
0
1
101
1
1
110
1
1
111
1
0
NOTE
The RT8, RT9, and RT10 samples do not affect start bit verification. If any
or all of the RT8, RT9, and RT10 start bit samples are logic 1s following a
successful start bit verification, the noise flag (NF) is set and the receiver
assumes that the bit is a start bit (logic 0).
To verify a stop bit and to detect noise, recovery logic takes samples at RT8, RT9, and RT10. Table 13-16
summarizes the results of the stop bit samples.
Table 13-16. Stop Bit Recovery
RT8, RT9, and RT10 Samples
Framing Error Flag
Noise Flag
000
1
0
001
1
1
010
1
1
011
0
1
100
1
1
101
0
1
110
0
1
111
0
0
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
409
Chapter 13 Serial Communication Interface (SCIV4)
In Figure 13-16 the verification samples RT3 and RT5 determine that the first low detected was noise and
not the beginning of a start bit. The RT clock is reset and the start bit search begins again. The noise flag
is not set because the noise occurred before the start bit was found.
START BIT
LSB
0
0
0
0
0
0
0
RT9
RT1
1
RT10
RT1
1
RT8
RT1
1
RT7
0
RT1
1
RT1
1
RT5
1
RT1
RXD
SAMPLES
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT6
RT5
RT4
RT3
RT2
RT4
RT3
RT CLOCK COUNT
RT2
RT CLOCK
RESET RT CLOCK
Figure 13-16. Start Bit Search Example 1
In Figure 13-17, verification sample at RT3 is high. The RT3 sample sets the noise flag. Although the
perceived bit time is misaligned, the data samples RT8, RT9, and RT10 are within the bit time and data
recovery is successful.
PERCEIVED START BIT
ACTUAL START BIT
LSB
1
RT1
RT1
RT1
RT1
0
1
0
0
0
0
0
RT10
1
RT9
1
RT8
1
RT7
1
RT1
RXD
SAMPLES
RT7
RT6
RT5
RT4
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT6
RT5
RT4
RT3
RT2
RT CLOCK COUNT
RT1
RT CLOCK
RESET RT CLOCK
Figure 13-17. Start Bit Search Example 2
MC9S12HZ256 Data Sheet, Rev. 2.04
410
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
In Figure 13-18, a large burst of noise is perceived as the beginning of a start bit, although the test sample
at RT5 is high. The RT5 sample sets the noise flag. Although this is a worst-case misalignment of
perceived bit time, the data samples RT8, RT9, and RT10 are within the bit time and data recovery is
successful.
PERCEIVED START BIT
LSB
ACTUAL START BIT
RT1
RT1
0
1
0
0
0
0
RT10
0
RT9
1
RT8
1
RT7
1
RT1
SAMPLES
RT1
RXD
RT9
RT8
RT7
RT6
RT5
RT4
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT6
RT5
RT4
RT3
RT CLOCK COUNT
RT2
RT CLOCK
RESET RT CLOCK
Figure 13-18. Start Bit Search Example 3
Figure 13-19 shows the effect of noise early in the start bit time. Although this noise does not affect proper
synchronization with the start bit time, it does set the noise flag.
PERCEIVED AND ACTUAL START BIT
LSB
1
RT1
RT1
RT1
1
1
1
1
0
RT1
1
RT1
1
RT1
1
RT1
1
RT1
SAMPLES
RT1
RXD
1
0
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT9
RT10
RT8
RT7
RT6
RT5
RT4
RT3
RT2
RT CLOCK COUNT
RT1
RT CLOCK
RESET RT CLOCK
Figure 13-19. Start Bit Search Example 4
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
411
Chapter 13 Serial Communication Interface (SCIV4)
Figure 13-20 shows a burst of noise near the beginning of the start bit that resets the RT clock. The sample
after the reset is low but is not preceded by three high samples that would qualify as a falling edge.
Depending on the timing of the start bit search and on the data, the frame may be missed entirely or it may
set the framing error flag.
1
0
0
0
0
0
0
0
0
RT1
RT1
1
RT1
0
RT1
0
RT1
RT1
1
RT1
RT1
1
RT1
RT1
1
RT1
RT1
1
RT1
1
RT1
1
RT1
1
RT1
1
RT1
1
RT1
SAMPLES
LSB
RT7
START BIT
NO START BIT FOUND
RXD
RT1
RT1
RT1
RT1
RT6
RT5
RT4
RT3
RT CLOCK COUNT
RT2
RT CLOCK
RESET RT CLOCK
Figure 13-20. Start Bit Search Example 5
In Figure 13-21, a noise burst makes the majority of data samples RT8, RT9, and RT10 high. This sets the
noise flag but does not reset the RT clock. In start bits only, the RT8, RT9, and RT10 data samples are
ignored.
START BIT
LSB
1
0
0
0
0
1
0
1
RT10
RT1
1
RT9
RT1
1
RT8
RT1
1
RT7
1
RT1
1
RT1
1
RT1
1
RT1
1
RT1
SAMPLES
RT1
RXD
RT3
RT2
RT1
RT16
RT15
RT14
RT13
RT12
RT11
RT6
RT5
RT4
RT3
RT2
RT CLOCK COUNT
RT1
RT CLOCK
RESET RT CLOCK
Figure 13-21. Start Bit Search Example 6
13.4.5.4
Framing Errors
If the data recovery logic does not detect a logic 1 where the stop bit should be in an incoming frame, it
sets the framing error flag, FE, in SCI status register 1 (SCISR1). A break character also sets the FE flag
because a break character has no stop bit. The FE flag is set at the same time that the RDRF flag is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
412
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.4.5.5
Baud Rate Tolerance
A transmitting device may be operating at a baud rate below or above the receiver baud rate. Accumulated
bit time misalignment can cause one of the three stop bit data samples (RT8, RT9, and RT10) to fall
outside the actual stop bit. A noise error will occur if the RT8, RT9, and RT10 samples are not all the same
logical values. A framing error will occur if the receiver clock is misaligned in such a way that the majority
of the RT8, RT9, and RT10 stop bit samples are a logic 0.
As the receiver samples an incoming frame, it re-synchronizes the RT clock on any valid falling edge
within the frame. Re synchronization within frames will correct a misalignment between transmitter bit
times and receiver bit times.
13.4.5.5.1
Slow Data Tolerance
Figure 13-22 shows how much a slow received frame can be misaligned without causing a noise error or
a framing error. The slow stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit data
samples at RT8, RT9, and RT10.
MSB
STOP
RT16
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
RT3
RT2
RT1
RECEIVER
RT CLOCK
DATA
SAMPLES
Figure 13-22. Slow Data
Let’s take RTr as receiver RT clock and RTt as transmitter RT clock.
For an 8-bit data character, it takes the receiver 9 bit times x 16 RTr cycles +7 RTr cycles =151 RTr cycles
to start data sampling of the stop bit.
With the misaligned character shown in Figure 13-22, the receiver counts 151 RTr cycles at the point when
the count of the transmitting device is 9 bit times x 16 RTt cycles = 144 RTt cycles.
The maximum percent difference between the receiver count and the transmitter count of a slow 8-bit data
character with no errors is:
((151 – 144) / 151) x 100 = 4.63%
For a 9-bit data character, it takes the receiver 10 bit times x 16 RTr cycles + 7 RTr cycles = 167 RTr cycles
to start data sampling of the stop bit.
With the misaligned character shown in Figure 13-22, the receiver counts 167 RTr cycles at the point when
the count of the transmitting device is 10 bit times x 16 RTt cycles = 160 RTt cycles.
The maximum percent difference between the receiver count and the transmitter count of a slow 9-bit
character with no errors is:
((167 – 160) / 167) X 100 = 4.19%
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
413
Chapter 13 Serial Communication Interface (SCIV4)
13.4.5.5.2
Fast Data Tolerance
Figure 13-23 shows how much a fast received frame can be misaligned. The fast stop bit ends at RT10
instead of RT16 but continues to be sampled at RT8, RT9, and RT10.
STOP
IDLE OR NEXT FRAME
RT16
RT15
RT14
RT13
RT12
RT11
RT10
RT9
RT8
RT7
RT6
RT5
RT4
RT3
RT2
RT1
RECEIVER
RT CLOCK
DATA
SAMPLES
Figure 13-23. Fast Data
For an 8-bit data character, it takes the receiver 9 bit times x 16 RTr cycles + 10 RTr cycles = 154 RTr
cycles to finish data sampling of the stop bit.
With the misaligned character shown in Figure 13-23, the receiver counts 154 RTr cycles at the point when
the count of the transmitting device is 10 bit times x 16 RTt cycles = 160 RTt cycles.
The maximum percent difference between the receiver count and the transmitter count of a fast 8-bit
character with no errors is:
((160 – 154) / 160) x 100 = 3.75%
For a 9-bit data character, it takes the receiver 10 bit times x 16 RTr cycles + 10 RTr cycles = 170 RTr
cycles to finish data sampling of the stop bit.
With the misaligned character shown in Figure 13-23, the receiver counts 170 RTr cycles at the point when
the count of the transmitting device is 11 bit times x 16 RTt cycles = 176 RTt cycles.
The maximum percent difference between the receiver count and the transmitter count of a fast 9-bit
character with no errors is:
((176 – 170) / 176) x 100 = 3.40%
13.4.5.6
Receiver Wakeup
To enable the SCI to ignore transmissions intended only for other receivers in multiple-receiver systems,
the receiver can be put into a standby state. Setting the receiver wakeup bit, RWU, in SCI control register 2
(SCICR2) puts the receiver into standby state during which receiver interrupts are disabled.The SCI will
continue to load the receive data into the SCIDRH/L registers, but it will not set the RDRF flag.
The transmitting device can address messages to selected receivers by including addressing information
in the initial frame or frames of each message.
The WAKE bit in SCI control register 1 (SCICR1) determines how the SCI is brought out of the standby
state to process an incoming message. The WAKE bit enables either idle line wakeup or address mark
wakeup.
MC9S12HZ256 Data Sheet, Rev. 2.04
414
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
13.4.5.6.1
Idle Input Line Wakeup (WAKE = 0)
In this wakeup method, an idle condition on the RXD pin clears the RWU bit and wakes up the SCI. The
initial frame or frames of every message contain addressing information. All receivers evaluate the
addressing information, and receivers for which the message is addressed process the frames that follow.
Any receiver for which a message is not addressed can set its RWU bit and return to the standby state. The
RWU bit remains set and the receiver remains on standby until another idle character appears on the RXD
pin.
Idle line wakeup requires that messages be separated by at least one idle character and that no message
contains idle characters.
The idle character that wakes a receiver does not set the receiver idle bit, IDLE, or the receive data register
full flag, RDRF.
The idle line type bit, ILT, determines whether the receiver begins counting logic 1s as idle character bits
after the start bit or after the stop bit. ILT is in SCI control register 1 (SCICR1).
13.4.5.6.2
Address Mark Wakeup (WAKE = 1)
In this wakeup method, a logic 1 in the most significant bit (MSB) position of a frame clears the RWU bit
and wakes up the SCI. The logic 1 in the MSB position marks a frame as an address frame that contains
addressing information. All receivers evaluate the addressing information, and the receivers for which the
message is addressed process the frames that follow. Any receiver for which a message is not addressed
can set its RWU bit and return to the standby state. The RWU bit remains set and the receiver remains on
standby until another address frame appears on the RXD pin.
The logic 1 MSB of an address frame clears the receiver’s RWU bit before the stop bit is received and sets
the RDRF flag.
Address mark wakeup allows messages to contain idle characters but requires that the MSB be reserved
for use in address frames.
NOTE
With the WAKE bit clear, setting the RWU bit after the RXD pin has been
idle can cause the receiver to wake up immediately.
13.4.6
Single-Wire Operation
Normally, the SCI uses two pins for transmitting and receiving. In single-wire operation, the RXD pin is
disconnected from the SCI. The SCI uses the TXD pin for both receiving and transmitting.
TRANSMITTER
RECEIVER
TXD
RXD
Figure 13-24. Single-Wire Operation (LOOPS = 1, RSRC = 1)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
415
Chapter 13 Serial Communication Interface (SCIV4)
Enable single-wire operation by setting the LOOPS bit and the receiver source bit, RSRC, in SCI control
register 1 (SCICR1). Setting the LOOPS bit disables the path from the RXD pin to the receiver. Setting
the RSRC bit connects the TXD pin to the receiver. Both the transmitter and receiver must be enabled
(TE = 1 and RE = 1).The TXDIR bit (SCISR2[1]) determines whether the TXD pin is going to be used as
an input (TXDIR = 0) or an output (TXDIR = 1) in this mode of operation.
NOTE
In single-wire operation data from the TXD pin is inverted if RXPOL is set.
13.4.7
Loop Operation
In loop operation the transmitter output goes to the receiver input. The RXD pin is disconnected from the
SCI
.
TRANSMITTER
TXD
RECEIVER
RXD
Figure 13-25. Loop Operation (LOOPS = 1, RSRC = 0)
Enable loop operation by setting the LOOPS bit and clearing the RSRC bit in SCI control register 1
(SCICR1). Setting the LOOPS bit disables the path from the RXD pin to the receiver. Clearing the RSRC
bit connects the transmitter output to the receiver input. Both the transmitter and receiver must be enabled
(TE = 1 and RE = 1).
NOTE
In loop operation data from the transmitter is not recognized by the receiver
if RXPOL and TXPOL are not the same.
13.5
Interrupts
This section describes the interrupt originated by the SCI block.The MCU must service the interrupt
requests. Table 13-17 lists the five interrupt sources of the SCI.
Table 13-17. SCI Interrupt Sources
Interrupt
Source
Local Enable
TDRE
SCISR1[7]
TIE
TC
SCISR1[6]
TCIE
RDRF
SCISR1[5]
RIE
OR
SCISR1[3]
Description
Active high level. Indicates that a byte was
transferred from SCIDRH/L to the transmit
shift register.
Active high level. Indicates that a transmit is
complete.
Active high level. The RDRF interrupt indicates
that received data is available in the SCI data
register.
Active high level. This interrupt indicates that
an overrun condition has occurred.
MC9S12HZ256 Data Sheet, Rev. 2.04
416
Freescale Semiconductor
Chapter 13 Serial Communication Interface (SCIV4)
Table 13-17. SCI Interrupt Sources
IDLE
13.5.1
SCISR1[4]
ILIE
Active high level. Indicates that receiver input
has become idle.
Description of Interrupt Operation
The SCI only originates interrupt requests. The following is a description of how the SCI makes a request
and how the MCU should acknowledge that request. The interrupt vector offset and interrupt number are
chip dependent. The SCI only has a single interrupt line (SCI interrupt signal, active high operation) and
all the following interrupts, when generated, are ORed together and issued through that port.
13.5.1.1
TDRE Description
The TDRE interrupt is set high by the SCI when the transmit shift register receives a byte from the SCI
data register. A TDRE interrupt indicates that the transmit data register (SCIDRH/L) is empty and that a
new byte can be written to the SCIDRH/L for transmission.Clear TDRE by reading SCI status register 1
with TDRE set and then writing to SCI data register low (SCIDRL).
13.5.1.2
TC Description
The TC interrupt is set by the SCI when a transmission has been completed.A TC interrupt indicates that
there is no transmission in progress. TC is set high when the TDRE flag is set and no data, preamble, or
break character is being transmitted. When TC is set, the TXD pin becomes idle (logic 1). Clear TC by
reading SCI status register 1 (SCISR1) with TC set and then writing to SCI data register low (SCIDRL).TC
is cleared automatically when data, preamble, or break is queued and ready to be sent.
13.5.1.3
RDRF Description
The RDRF interrupt is set when the data in the receive shift register transfers to the SCI data register. A
RDRF interrupt indicates that the received data has been transferred to the SCI data register and that the
byte can now be read by the MCU. The RDRF interrupt is cleared by reading the SCI status register one
(SCISR1) and then reading SCI data register low (SCIDRL).
13.5.1.4
OR Description
The OR interrupt is set when software fails to read the SCI data register before the receive shift register
receives the next frame. The newly acquired data in the shift register will be lost in this case, but the data
already in the SCI data registers is not affected. The OR interrupt is cleared by reading the SCI status
register one (SCISR1) and then reading SCI data register low (SCIDRL).
13.5.1.5
IDLE Description
The IDLE interrupt is set when 10 consecutive logic 1s (if M = 0) or 11 consecutive logic 1s (if M = 1)
appear on the receiver input. After the IDLE is cleared, a valid frame must again set the RDRF flag before
an idle condition can set the IDLE flag. Clear IDLE by reading SCI status register 1 (SCISR1) with IDLE
set and then reading SCI data register low (SCIDRL).
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
417
Chapter 13 Serial Communication Interface (SCIV4)
13.5.2
Recovery from Wait Mode
The SCI interrupt request can be used to bring the CPU out of wait mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
418
Freescale Semiconductor
Chapter 14
Serial Peripheral Interface (SPIV3)
14.1
Introduction
The SPI module allows a duplex, synchronous, serial communication between the MCU and peripheral
devices. Software can poll the SPI status flags or the SPI operation can be interrupt driven.
14.1.1
Features
The SPI includes these distinctive features:
• Master mode and slave mode
• Bidirectional mode
• Slave select output
• Mode fault error flag with CPU interrupt capability
• Double-buffered data register
• Serial clock with programmable polarity and phase
• Control of SPI operation during wait mode
14.1.2
Modes of Operation
The SPI functions in three modes, run, wait, and stop.
• Run Mode
This is the basic mode of operation.
• Wait Mode
SPI operation in wait mode is a configurable low power mode, controlled by the SPISWAI bit
located in the SPICR2 register. In wait mode, if the SPISWAI bit is clear, the SPI operates like in
Run Mode. If the SPISWAI bit is set, the SPI goes into a power conservative state, with the SPI
clock generation turned off. If the SPI is configured as a master, any transmission in progress stops,
but is resumed after CPU goes into Run Mode. If the SPI is configured as a slave, reception and
transmission of a byte continues, so that the slave stays synchronized to the master.
• Stop Mode
The SPI is inactive in stop mode for reduced power consumption. If the SPI is configured as a
master, any transmission in progress stops, but is resumed after CPU goes into run mode. If the SPI
is configured as a slave, reception and transmission of a byte continues, so that the slave stays
synchronized to the master.
This is a high level description only, detailed descriptions of operating modes are contained in
Section 14.4, “Functional Description.”
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
419
Chapter 14 Serial Peripheral Interface (SPIV3)
14.1.3
Block Diagram
Figure 14-1 gives an overview on the SPI architecture. The main parts of the SPI are status, control, and
data registers, shifter logic, baud rate generator, master/slave control logic, and port control logic.
SPI
2
SPI Control Register 1
BIDIROE
2
SPI Control Register 2
SPC0
SPI Status Register
SPIF
Slave
Control
MODF SPTEF
CPOL
CPHA
Phase + SCK in
Slave Baud Rate Polarity
Control
Master Baud Rate
Phase + SCK out
Polarity
Control
Interrupt Control
SPI
Interrupt
Request
Baud Rate Generator
Master
Control
Counter
Bus Clock
3
SPR
Port
Control
Logic
SCK
SS
Prescaler Clock Select
SPPR
MOSI
Shift
Clock
Baud Rate
Sample
Clock
3
Shifter
SPI Baud Rate Register
data in
LSBFE=1
LSBFE=0
8
SPI Data Register
8
MSB
LSBFE=0
LSBFE=1
LSBFE=0
LSB
LSBFE=1
data out
Figure 14-1. SPI Block Diagram
14.2
External Signal Description
This section lists the name and description of all ports including inputs and outputs that do, or may, connect
off chip. The SPI module has a total of four external pins.
14.2.1
MOSI — Master Out/Slave In Pin
This pin is used to transmit data out of the SPI module when it is configured as a master and receive data
when it is configured as slave.
MC9S12HZ256 Data Sheet, Rev. 2.04
420
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
14.2.2
MISO — Master In/Slave Out Pin
This pin is used to transmit data out of the SPI module when it is configured as a slave and receive data
when it is configured as master.
14.2.3
SS — Slave Select Pin
This pin is used to output the select signal from the SPI module to another peripheral with which a data
transfer is to take place when its configured as a master and its used as an input to receive the slave select
signal when the SPI is configured as slave.
14.2.4
SCK — Serial Clock Pin
This pin is used to output the clock with respect to which the SPI transfers data or receive clock in case of
slave.
14.3
Memory Map and Register Definition
This section provides a detailed description of address space and registers used by the SPI.
The memory map for the SPI is given below in Table 14-1. The address listed for each register is the sum
of a base address and an address offset. The base address is defined at the SoC level and the address offset
is defined at the module level. Reads from the reserved bits return zeros and writes to the reserved bits have
no effect.
14.3.1
Module Memory Map
Table 14-1. SPI Memory Map
Address
0x0000
0x0001
0x0002
0x0003
0x0004
0x0005
0x0006
0x0007
Use
SPI Control Register 1 (SPICR1)
SPI Control Register 2 (SPICR2)
SPI Baud Rate Register (SPIBR)
SPI Status Register (SPISR)
Reserved
SPI Data Register (SPIDR)
Reserved
Reserved
Access
R/W
R/W1
R/W1
R2
— 2,3
R/W
— 2,3
— 2,3
1
Certain bits are non-writable.
Writes to this register are ignored.
3 Reading from this register returns all zeros.
2
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
421
Chapter 14 Serial Peripheral Interface (SPIV3)
14.3.2
Register Descriptions
This section consists of register descriptions in address order. Each description includes a standard register
diagram with an associated figure number. Details of register bit and field function follow the register
diagrams, in bit order.
Name
R
SPICR1
W
R
SPICR2
7
6
5
4
3
2
1
0
SPIE
SPE
SPTIE
MSTR
CPOL
CPHA
SSOE
LSBFE
0
0
0
MODFEN
BIDIROE
SPISWAI
SPC0
SPPR2
SPPR1
SPPR0
SPR2
SPR1
SPR0
SPIF
0
SPTEF
MODF
0
0
0
0
Bit 7
6
5
4
3
2
2
Bit 0
W
R
SPIBR
0
W
R
SPISR
0
0
W
R
Reserved
W
R
SPIDR
W
R
Reserved
W
R
Reserved
W
= Unimplemented or Reserved
Figure 14-2. SPI Register Summary
14.3.2.1
SPI Control Register 1 (SPICR1)
7
6
5
4
3
2
1
0
SPIE
SPE
SPTIE
MSTR
CPOL
CPHA
SSOE
LSBFE
0
0
0
0
0
1
0
0
R
W
Reset
Figure 14-3. SPI Control Register 1 (SPICR1)
Read: anytime
Write: anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
422
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
Table 14-2. SPICR1 Field Descriptions
Field
Description
7
SPIE
SPI Interrupt Enable Bit — This bit enables SPI interrupt requests, if SPIF or MODF status flag is set.
0 SPI interrupts disabled.
1 SPI interrupts enabled.
6
SPE
SPI System Enable Bit — This bit enables the SPI system and dedicates the SPI port pins to SPI system
functions. If SPE is cleared, SPI is disabled and forced into idle state, status bits in SPISR register are reset.
0 SPI disabled (lower power consumption).
1 SPI enabled, port pins are dedicated to SPI functions.
5
SPTIE
SPI Transmit Interrupt Enable — This bit enables SPI interrupt requests, if SPTEF flag is set.
0 SPTEF interrupt disabled.
1 SPTEF interrupt enabled.
4
MSTR
SPI Master/Slave Mode Select Bit — This bit selects, if the SPI operates in master or slave mode. Switching
the SPI from master to slave or vice versa forces the SPI system into idle state.
0 SPI is in slave mode
1 SPI is in master mode
3
CPOL
SPI Clock Polarity Bit — This bit selects an inverted or non-inverted SPI clock. To transmit data between SPI
modules, the SPI modules must have identical CPOL values. In master mode, a change of this bit will abort a
transmission in progress and force the SPI system into idle state.
0 Active-high clocks selected. In idle state SCK is low.
1 Active-low clocks selected. In idle state SCK is high.
2
CPHA
SPI Clock Phase Bit — This bit is used to select the SPI clock format. In master mode, a change of this bit will
abort a transmission in progress and force the SPI system into idle state.
0 Sampling of data occurs at odd edges (1,3,5,...,15) of the SCK clock
1 Sampling of data occurs at even edges (2,4,6,...,16) of the SCK clock
1
SSOE
Slave Select Output Enable — The SS output feature is enabled only in master mode, if MODFEN is set, by
asserting the SSOE as shown in Table 14-3. In master mode, a change of this bit will abort a transmission in
progress and force the SPI system into idle state.
0
LSBFE
LSB-First Enable — This bit does not affect the position of the MSB and LSB in the data register. Reads and
writes of the data register always have the MSB in bit 7. In master mode, a change of this bit will abort a
transmission in progress and force the SPI system into idle state.
0 Data is transferred most significant bit first.
1 Data is transferred least significant bit first.
Table 14-3. SS Input / Output Selection
MODFEN
SSOE
Master Mode
Slave Mode
0
0
SS not used by SPI
SS input
0
1
SS not used by SPI
SS input
1
0
SS input with MODF feature
SS input
1
1
SS is slave select output
SS input
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
423
Chapter 14 Serial Peripheral Interface (SPIV3)
14.3.2.2
R
SPI Control Register 2 (SPICR2)
7
6
5
0
0
0
4
3
MODFEN
BIDIROE
0
0
2
1
0
SPISWAI
SPC0
0
0
0
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 14-4. SPI Control Register 2 (SPICR2)
Read: anytime
Write: anytime; writes to the reserved bits have no effect
Table 14-4. SPICR2 Field Descriptions
Field
Description
4
MODFEN
Mode Fault Enable Bit — This bit allows the MODF failure being detected. If the SPI is in master mode and
MODFEN is cleared, then the SS port pin is not used by the SPI. In slave mode, the SS is available only as an
input regardless of the value of MODFEN. For an overview on the impact of the MODFEN bit on the SS port pin
configuration refer to Table 14-3. In master mode, a change of this bit will abort a transmission in progress and
force the SPI system into idle state.
0 SS port pin is not used by the SPI
1 SS port pin with MODF feature
3
BIDIROE
Output Enable in the Bidirectional Mode of Operation — This bit controls the MOSI and MISO output buffer
of the SPI, when in bidirectional mode of operation (SPC0 is set). In master mode this bit controls the output
buffer of the MOSI port, in slave mode it controls the output buffer of the MISO port. In master mode, with SPC0
set, a change of this bit will abort a transmission in progress and force the SPI into idle state.
0 Output buffer disabled
1 Output buffer enabled
1
SPISWAI
SPI Stop in Wait Mode Bit — This bit is used for power conservation while in wait mode.
0 SPI clock operates normally in wait mode
1 Stop SPI clock generation when in wait mode
0
SPC0
Serial Pin Control Bit 0 — This bit enables bidirectional pin configurations as shown in Table 14-5. In master
mode, a change of this bit will abort a transmission in progress and force the SPI system into idle state
Table 14-5. Bidirectional Pin Configurations
Pin Mode
SPC0
BIDIROE
MISO
MOSI
Master Mode of Operation
Normal
0
X
Master In
Master Out
Bidirectional
1
0
MISO not used by SPI
Master In
1
Master I/O
Slave Mode of Operation
Normal
0
X
Slave Out
Slave In
Bidirectional
1
0
Slave In
MOSI not used by SPI
1
Slave I/O
MC9S12HZ256 Data Sheet, Rev. 2.04
424
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
14.3.2.3
SPI Baud Rate Register (SPIBR)
7
R
6
5
4
3
SPPR2
SPPR1
SPPR0
0
0
0
0
2
1
0
SPR2
SPR1
SPR0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 14-5. SPI Baud Rate Register (SPIBR)
Read: anytime
Write: anytime; writes to the reserved bits have no effect
Table 14-6. SPIBR Field Descriptions
Field
Description
6:4
SPPR[2:0]
SPI Baud Rate Preselection Bits — These bits specify the SPI baud rates as shown in Table 14-7. In master
mode, a change of these bits will abort a transmission in progress and force the SPI system into idle state.
2:0
SPR[2:0}
SPI Baud Rate Selection Bits — These bits specify the SPI baud rates as shown in Table 14-7. In master mode,
a change of these bits will abort a transmission in progress and force the SPI system into idle state.
The baud rate divisor equation is as follows:
BaudRateDivisor = ( SPPR + 1 ) • 2
( SPR + 1 )
The baud rate can be calculated with the following equation:
Baud Rate = BusClock ⁄ BaudRateDivisor
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
425
Chapter 14 Serial Peripheral Interface (SPIV3)
Table 14-7. Example SPI Baud Rate Selection (25 MHz Bus Clock)
SPPR2
SPPR1
SPPR0
SPR2
SPR1
SPR0
Baud Rate
Divisor
Baud Rate
0
0
0
0
0
0
2
12.5 MHz
0
0
0
0
0
1
4
6.25 MHz
0
0
0
0
1
0
8
3.125 MHz
0
0
0
0
1
1
16
1.5625 MHz
0
0
0
1
0
0
32
781.25 kHz
0
0
0
1
0
1
64
390.63 kHz
0
0
0
1
1
0
128
195.31 kHz
0
0
0
1
1
1
256
97.66 kHz
0
0
1
0
0
0
4
6.25 MHz
0
0
1
0
0
1
8
3.125 MHz
0
0
1
0
1
0
16
1.5625 MHz
0
0
1
0
1
1
32
781.25 kHz
0
0
1
1
0
0
64
390.63 kHz
0
0
1
1
0
1
128
195.31 kHz
0
0
1
1
1
0
256
97.66 kHz
0
0
1
1
1
1
512
48.83 kHz
0
1
0
0
0
0
6
4.16667 MHz
0
1
0
0
0
1
12
2.08333 MHz
0
1
0
0
1
0
24
1.04167 MHz
0
1
0
0
1
1
48
520.83 kHz
0
1
0
1
0
0
96
260.42 kHz
0
1
0
1
0
1
192
130.21 kHz
0
1
0
1
1
0
384
65.10 kHz
0
1
0
1
1
1
768
32.55 kHz
0
1
1
0
0
0
8
3.125 MHz
0
1
1
0
0
1
16
1.5625 MHz
0
1
1
0
1
0
32
781.25 kHz
0
1
1
0
1
1
64
390.63 kHz
0
1
1
1
0
0
128
195.31 kHz
0
1
1
1
0
1
256
97.66 kHz
0
1
1
1
1
0
512
48.83 kHz
0
1
1
1
1
1
1024
24.41 kHz
1
0
0
0
0
0
10
2.5 MHz
1
0
0
0
0
1
20
1.25 MHz
1
0
0
0
1
0
40
625 kHz
1
0
0
0
1
1
80
312.5 kHz
1
0
0
1
0
0
160
156.25 kHz
1
0
0
1
0
1
320
78.13 kHz
1
0
0
1
1
0
640
39.06 kHz
MC9S12HZ256 Data Sheet, Rev. 2.04
426
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
Table 14-7. Example SPI Baud Rate Selection (25 MHz Bus Clock) (continued)
SPPR2
SPPR1
SPPR0
SPR2
SPR1
SPR0
Baud Rate
Divisor
Baud Rate
1
0
0
1
1
1
1280
19.53 kHz
1
0
1
0
0
0
12
2.08333 MHz
1
0
1
0
0
1
24
1.04167 MHz
1
0
1
0
1
0
48
520.83 kHz
1
0
1
0
1
1
96
260.42 kHz
1
0
1
1
0
0
192
130.21 kHz
1
0
1
1
0
1
384
65.10 kHz
1
0
1
1
1
0
768
32.55 kHz
1
0
1
1
1
1
1536
16.28 kHz
1
1
0
0
0
0
14
1.78571 MHz
1
1
0
0
0
1
28
892.86 kHz
1
1
0
0
1
0
56
446.43 kHz
1
1
0
0
1
1
112
223.21 kHz
1
1
0
1
0
0
224
111.61 kHz
1
1
0
1
0
1
448
55.80 kHz
1
1
0
1
1
0
896
27.90 kHz
1
1
0
1
1
1
1792
13.95 kHz
1
1
1
0
0
0
16
1.5625 MHz
1
1
1
0
0
1
32
781.25 kHz
1
1
1
0
1
0
64
390.63 kHz
1
1
1
0
1
1
128
195.31 kHz
1
1
1
1
0
0
256
97.66 kHz
1
1
1
1
0
1
512
48.83 kHz
1
1
1
1
1
0
1024
24.41 kHz
1
1
1
1
1
1
2048
12.21 kHz
NOTE
In slave mode of SPI S-clock speed DIV2 is not supported.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
427
Chapter 14 Serial Peripheral Interface (SPIV3)
14.3.2.4
R
SPI Status Register (SPISR)
7
6
5
4
3
2
1
0
SPIF
0
SPTEF
MODF
0
0
0
0
0
0
1
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 14-6. SPI Status Register (SPISR)
Read: anytime
Write: has no effect
Table 14-8. SPISR Field Descriptions
Field
Description
7
SPIF
SPIF Interrupt Flag — This bit is set after a received data byte has been transferred into the SPI Data Register.
This bit is cleared by reading the SPISR register (with SPIF set) followed by a read access to the SPI Data
Register.
0 Transfer not yet complete
1 New data copied to SPIDR
5
SPTEF
SPI Transmit Empty Interrupt Flag — If set, this bit indicates that the transmit data register is empty. To clear
this bit and place data into the transmit data register, SPISR has to be read with SPTEF = 1, followed by a write
to SPIDR. Any write to the SPI Data Register without reading SPTEF = 1, is effectively ignored.
0 SPI Data register not empty
1 SPI Data register empty
4
MODF
Mode Fault Flag — This bit is set if the SS input becomes low while the SPI is configured as a master and mode
fault detection is enabled, MODFEN bit of SPICR2 register is set. Refer to MODFEN bit description in
Section 14.3.2.2, “SPI Control Register 2 (SPICR2).” The flag is cleared automatically by a read of the SPI Status
Register (with MODF set) followed by a write to the SPI Control Register 1.
0 Mode fault has not occurred.
1 Mode fault has occurred.
14.3.2.5
SPI Data Register (SPIDR)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
2
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
= Unimplemented or Reserved
Figure 14-7. SPI Data Register (SPIDR)
Read: anytime; normally read only after SPIF is set
Write: anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
428
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
The SPI Data Register is both the input and output register for SPI data. A write to this register allows a
data byte to be queued and transmitted. For a SPI configured as a master, a queued data byte is transmitted
immediately after the previous transmission has completed. The SPI Transmitter Empty Flag SPTEF in
the SPISR register indicates when the SPI Data Register is ready to accept new data.
Reading the data can occur anytime from after the SPIF is set to before the end of the next transfer. If the
SPIF is not serviced by the end of the successive transfers, those data bytes are lost and the data within the
SPIDR retains the first byte until SPIF is serviced.
14.4
Functional Description
The SPI module allows a duplex, synchronous, serial communication between the MCU and peripheral
devices. Software can poll the SPI status flags or SPI operation can be interrupt driven.
The SPI system is enabled by setting the SPI enable (SPE) bit in SPI Control Register 1. While SPE bit is
set, the four associated SPI port pins are dedicated to the SPI function as:
• Slave select (SS)
• Serial clock (SCK)
• Master out/slave in (MOSI)
• Master in/slave out (MISO)
The main element of the SPI system is the SPI Data Register. The 8-bit data register in the master and the
8-bit data register in the slave are linked by the MOSI and MISO pins to form a distributed 16-bit register.
When a data transfer operation is performed, this 16-bit register is serially shifted eight bit positions by the
S-clock from the master, so data is exchanged between the master and the slave. Data written to the master
SPI Data Register becomes the output data for the slave, and data read from the master SPI Data Register
after a transfer operation is the input data from the slave.
A read of SPISR with SPTEF = 1 followed by a write to SPIDR puts data into the transmit data register.
When a transfer is complete, received data is moved into the receive data register. Data may be read from
this double-buffered system any time before the next transfer has completed. This 8-bit data register acts
as the SPI receive data register for reads and as the SPI transmit data register for writes. A single SPI
register address is used for reading data from the read data buffer and for writing data to the transmit data
register.
The clock phase control bit (CPHA) and a clock polarity control bit (CPOL) in the SPI Control Register 1
(SPICR1) select one of four possible clock formats to be used by the SPI system. The CPOL bit simply
selects a non-inverted or inverted clock. The CPHA bit is used to accommodate two fundamentally
different protocols by sampling data on odd numbered SCK edges or on even numbered SCK edges (see
Section 14.4.3, “Transmission Formats”).
The SPI can be configured to operate as a master or as a slave. When the MSTR bit in SPI Control
Register1 is set, master mode is selected, when the MSTR bit is clear, slave mode is selected.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
429
Chapter 14 Serial Peripheral Interface (SPIV3)
14.4.1
Master Mode
The SPI operates in master mode when the MSTR bit is set. Only a master SPI module can initiate
transmissions. A transmission begins by writing to the master SPI Data Register. If the shift register is
empty, the byte immediately transfers to the shift register. The byte begins shifting out on the MOSI pin
under the control of the serial clock.
• S-clock
The SPR2, SPR1, and SPR0 baud rate selection bits in conjunction with the SPPR2, SPPR1, and
SPPR0 baud rate preselection bits in the SPI Baud Rate register control the baud rate generator and
determine the speed of the transmission. The SCK pin is the SPI clock output. Through the SCK
pin, the baud rate generator of the master controls the shift register of the slave peripheral.
• MOSI and MISO Pins
In master mode, the function of the serial data output pin (MOSI) and the serial data input pin
(MISO) is determined by the SPC0 and BIDIROE control bits.
• SS Pin
If MODFEN and SSOE bit are set, the SS pin is configured as slave select output. The SS output
becomes low during each transmission and is high when the SPI is in idle state.
If MODFEN is set and SSOE is cleared, the SS pin is configured as input for detecting mode fault
error. If the SS input becomes low this indicates a mode fault error where another master tries to
drive the MOSI and SCK lines. In this case, the SPI immediately switches to slave mode, by
clearing the MSTR bit and also disables the slave output buffer MISO (or SISO in bidirectional
mode). So the result is that all outputs are disabled and SCK, MOSI and MISO are inputs. If a
transmission is in progress when the mode fault occurs, the transmission is aborted and the SPI is
forced into idle state.
This mode fault error also sets the mode fault (MODF) flag in the SPI Status Register (SPISR). If the SPI
interrupt enable bit (SPIE) is set when the MODF flag gets set, then an SPI interrupt sequence is also
requested.
When a write to the SPI Data Register in the master occurs, there is a half SCK-cycle delay. After the delay,
SCK is started within the master. The rest of the transfer operation differs slightly, depending on the clock
format specified by the SPI clock phase bit, CPHA, in SPI Control Register 1 (see Section 14.4.3,
“Transmission Formats”).
NOTE
A change of the bits CPOL, CPHA, SSOE, LSBFE, MODFEN, SPC0,
BIDIROE with SPC0 set, SPPR2–SPPR0 and SPR2–SPR0 in master mode
will abort a transmission in progress and force the SPI into idle state. The
remote slave cannot detect this, therefore the master has to ensure that the
remote slave is set back to idle state.
MC9S12HZ256 Data Sheet, Rev. 2.04
430
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
14.4.2
Slave Mode
The SPI operates in slave mode when the MSTR bit in SPI Control Register1 is clear.
• SCK Clock
In slave mode, SCK is the SPI clock input from the master.
• MISO and MOSI Pins
In slave mode, the function of the serial data output pin (MISO) and serial data input pin (MOSI)
is determined by the SPC0 bit and BIDIROE bit in SPI Control Register 2.
• SS Pin
The SS pin is the slave select input. Before a data transmission occurs, the SS pin of the slave SPI
must be low. SS must remain low until the transmission is complete. If SS goes high, the SPI is
forced into idle state.
The SS input also controls the serial data output pin, if SS is high (not selected), the serial data
output pin is high impedance, and, if SS is low the first bit in the SPI Data Register is driven out of
the serial data output pin. Also, if the slave is not selected (SS is high), then the SCK input is
ignored and no internal shifting of the SPI shift register takes place.
Although the SPI is capable of duplex operation, some SPI peripherals are capable of only receiving SPI
data in a slave mode. For these simpler devices, there is no serial data out pin.
NOTE
When peripherals with duplex capability are used, take care not to
simultaneously enable two receivers whose serial outputs drive the same
system slave’s serial data output line.
As long as no more than one slave device drives the system slave’s serial data output line, it is possible for
several slaves to receive the same transmission from a master, although the master would not receive return
information from all of the receiving slaves.
If the CPHA bit in SPI Control Register 1 is clear, odd numbered edges on the SCK input cause the data
at the serial data input pin to be latched. Even numbered edges cause the value previously latched from the
serial data input pin to shift into the LSB or MSB of the SPI shift register, depending on the LSBFE bit.
If the CPHA bit is set, even numbered edges on the SCK input cause the data at the serial data input pin to
be latched. Odd numbered edges cause the value previously latched from the serial data input pin to shift
into the LSB or MSB of the SPI shift register, depending on the LSBFE bit.
When CPHA is set, the first edge is used to get the first data bit onto the serial data output pin. When CPHA
is clear and the SS input is low (slave selected), the first bit of the SPI data is driven out of the serial data
output pin. After the eighth shift, the transfer is considered complete and the received data is transferred
into the SPI Data Register. To indicate transfer is complete, the SPIF flag in the SPI Status Register is set.
NOTE
A change of the bits CPOL, CPHA, SSOE, LSBFE, MODFEN, SPC0 and
BIDIROE with SPC0 set in slave mode will corrupt a transmission in
progress and has to be avoided.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
431
Chapter 14 Serial Peripheral Interface (SPIV3)
14.4.3
Transmission Formats
During an SPI transmission, data is transmitted (shifted out serially) and received (shifted in serially)
simultaneously. The serial clock (SCK) synchronizes shifting and sampling of the information on the two
serial data lines. A slave select line allows selection of an individual slave SPI device, slave devices that
are not selected do not interfere with SPI bus activities. Optionally, on a master SPI device, the slave select
line can be used to indicate multiple-master bus contention.
MASTER SPI
SHIFT REGISTER
BAUD RATE
GENERATOR
SLAVE SPI
MISO
MISO
MOSI
MOSI
SCK
SCK
SS
VDD
SHIFT REGISTER
SS
Figure 14-8. Master/Slave Transfer Block Diagram
14.4.3.1
Clock Phase and Polarity Controls
Using two bits in the SPI Control Register1, software selects one of four combinations of serial clock phase
and polarity.
The CPOL clock polarity control bit specifies an active high or low clock and has no significant effect on
the transmission format.
The CPHA clock phase control bit selects one of two fundamentally different transmission formats.
Clock phase and polarity should be identical for the master SPI device and the communicating slave
device. In some cases, the phase and polarity are changed between transmissions to allow a master device
to communicate with peripheral slaves having different requirements.
14.4.3.2
CPHA = 0 Transfer Format
The first edge on the SCK line is used to clock the first data bit of the slave into the master and the first
data bit of the master into the slave. In some peripherals, the first bit of the slave’s data is available at the
slave’s data out pin as soon as the slave is selected. In this format, the first SCK edge is issued a half cycle
after SS has become low.
A half SCK cycle later, the second edge appears on the SCK line. When this second edge occurs, the value
previously latched from the serial data input pin is shifted into the LSB or MSB of the shift register,
depending on LSBFE bit.
After this second edge, the next bit of the SPI master data is transmitted out of the serial data output pin of
the master to the serial input pin on the slave. This process continues for a total of 16 edges on the SCK
line, with data being latched on odd numbered edges and shifted on even numbered edges.
MC9S12HZ256 Data Sheet, Rev. 2.04
432
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
Data reception is double buffered. Data is shifted serially into the SPI shift register during the transfer and
is transferred to the parallel SPI Data Register after the last bit is shifted in.
After the 16th (last) SCK edge:
• Data that was previously in the master SPI Data Register should now be in the slave data register
and the data that was in the slave data register should be in the master.
• The SPIF flag in the SPI Status Register is set indicating that the transfer is complete.
Figure 14-9 is a timing diagram of an SPI transfer where CPHA = 0. SCK waveforms are shown for
CPOL = 0 and CPOL = 1. The diagram may be interpreted as a master or slave timing diagram because
the SCK, MISO, and MOSI pins are connected directly between the master and the slave. The MISO signal
is the output from the slave and the MOSI signal is the output from the master. The SS pin of the master
must be either high or reconfigured as a general-purpose output not affecting the SPI.
End of Idle State
Begin
1
SCK Edge Nr.
2
3
4
5
6
7
8
Begin of Idle State
End
Transfer
9
10
11
12
13 14
15
16
Bit 1
Bit 6
LSB Minimum 1/2 SCK
for tT, tl, tL
MSB
SCK (CPOL = 0)
SCK (CPOL = 1)
If next transfer begins here
SAMPLE I
MOSI/MISO
CHANGE O
MOSI pin
CHANGE O
MISO pin
SEL SS (O)
Master only
SEL SS (I)
tL
tT
MSB first (LSBFE = 0): MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
LSB first (LSBFE = 1): LSB
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
tL = Minimum leading time before the first SCK edge
tT = Minimum trailing time after the last SCK edge
tI = Minimum idling time between transfers (minimum SS high time)
tL, tT, and tI are guaranteed for the master mode and required for the slave mode.
tI
tL
Figure 14-9. SPI Clock Format 0 (CPHA = 0)
In slave mode, if the SS line is not deasserted between the successive transmissions then the content of the
SPI Data Register is not transmitted, instead the last received byte is transmitted. If the SS line is deasserted
for at least minimum idle time (half SCK cycle) between successive transmissions then the content of the
SPI Data Register is transmitted.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
433
Chapter 14 Serial Peripheral Interface (SPIV3)
In master mode, with slave select output enabled the SS line is always deasserted and reasserted between
successive transfers for at least minimum idle time.
14.4.3.3
CPHA = 1 Transfer Format
Some peripherals require the first SCK edge before the first data bit becomes available at the data out pin,
the second edge clocks data into the system. In this format, the first SCK edge is issued by setting the
CPHA bit at the beginning of the 8-cycle transfer operation.
The first edge of SCK occurs immediately after the half SCK clock cycle synchronization delay. This first
edge commands the slave to transfer its first data bit to the serial data input pin of the master.
A half SCK cycle later, the second edge appears on the SCK pin. This is the latching edge for both the
master and slave.
When the third edge occurs, the value previously latched from the serial data input pin is shifted into the
LSB or MSB of the SPI shift register, depending on LSBFE bit. After this edge, the next bit of the master
data is coupled out of the serial data output pin of the master to the serial input pin on the slave.
This process continues for a total of 16 edges on the SCK line with data being latched on even numbered
edges and shifting taking place on odd numbered edges.
Data reception is double buffered, data is serially shifted into the SPI shift register during the transfer and
is transferred to the parallel SPI Data Register after the last bit is shifted in.
After the 16th SCK edge:
• Data that was previously in the SPI Data Register of the master is now in the data register of the
slave, and data that was in the data register of the slave is in the master.
• The SPIF flag bit in SPISR is set indicating that the transfer is complete.
Figure 14-10 shows two clocking variations for CPHA = 1. The diagram may be interpreted as a master or
slave timing diagram because the SCK, MISO, and MOSI pins are connected directly between the master
and the slave. The MISO signal is the output from the slave, and the MOSI signal is the output from the
master. The SS line is the slave select input to the slave. The SS pin of the master must be either high or
reconfigured as a general-purpose output not affecting the SPI.
The SS line can remain active low between successive transfers (can be tied low at all times). This format
is sometimes preferred in systems having a single fixed master and a single slave that drive the MISO data
line.
• Back-to-back transfers in master mode
In master mode, if a transmission has completed and a new data byte is available in the SPI Data Register,
this byte is send out immediately without a trailing and minimum idle time.
The SPI interrupt request flag (SPIF) is common to both the master and slave modes. SPIF gets set one
half SCK cycle after the last SCK edge.
MC9S12HZ256 Data Sheet, Rev. 2.04
434
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
End of Idle State
Begin
SCK Edge Nr.
1
2
3
4
End
Transfer
5
6
7
8
9
10
11
12
13 14
Begin of Idle State
15
16
SCK (CPOL = 0)
SCK (CPOL = 1)
If next transfer begins here
SAMPLE I
MOSI/MISO
CHANGE O
MOSI pin
CHANGE O
MISO pin
SEL SS (O)
Master only
SEL SS (I)
tL
tT
tI
tL
MSB first (LSBFE = 0):
LSB first (LSBFE = 1):
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
LSB Minimum 1/2 SCK
for tT, tl, tL
LSB
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
MSB
tL = Minimum leading time before the first SCK edge, not required for back to back transfers
tT = Minimum trailing time after the last SCK edge
tI = Minimum idling time between transfers (minimum SS high time), not required for back to back transfers
Figure 14-10. SPI Clock Format 1 (CPHA = 1)
14.4.4
SPI Baud Rate Generation
Baud rate generation consists of a series of divider stages. Six bits in the SPI Baud Rate register (SPPR2,
SPPR1, SPPR0, SPR2, SPR1, and SPR0) determine the divisor to the SPI module clock which results in
the SPI baud rate.
The SPI clock rate is determined by the product of the value in the baud rate preselection bits
(SPPR2–SPPR0) and the value in the baud rate selection bits (SPR2–SPR0). The module clock divisor
equation is shown in Figure 14-11
When all bits are clear (the default condition), the SPI module clock is divided by 2. When the selection
bits (SPR2–SPR0) are 001 and the preselection bits (SPPR2–SPPR0) are 000, the module clock divisor
becomes 4. When the selection bits are 010, the module clock divisor becomes 8 etc.
When the preselection bits are 001, the divisor determined by the selection bits is multiplied by 2. When
the preselection bits are 010, the divisor is multiplied by 3, etc. See Table 14-7 for baud rate calculations
for all bit conditions, based on a 25-MHz bus clock. The two sets of selects allows the clock to be divided
by a non-power of two to achieve other baud rates such as divide by 6, divide by 10, etc.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
435
Chapter 14 Serial Peripheral Interface (SPIV3)
The baud rate generator is activated only when the SPI is in the master mode and a serial transfer is taking
place. In the other cases, the divider is disabled to decrease IDD current.
BaudRateDivisor = ( SPPR + 1 ) • 2
( SPR + 1 )
Figure 14-11. Baud Rate Divisor Equation
14.4.5
14.4.5.1
Special Features
SS Output
The SS output feature automatically drives the SS pin low during transmission to select external devices
and drives it high during idle to deselect external devices. When SS output is selected, the SS output pin
is connected to the SS input pin of the external device.
The SS output is available only in master mode during normal SPI operation by asserting SSOE and
MODFEN bit as shown in Table 14-3.
The mode fault feature is disabled while SS output is enabled.
NOTE
Care must be taken when using the SS output feature in a multimaster
system because the mode fault feature is not available for detecting system
errors between masters.
14.4.5.2
Bidirectional Mode (MOSI or MISO)
The bidirectional mode is selected when the SPC0 bit is set in SPI Control Register 2 (see Table 14-9). In
this mode, the SPI uses only one serial data pin for the interface with external device(s). The MSTR bit
decides which pin to use. The MOSI pin becomes the serial data I/O (MOMI) pin for the master mode, and
the MISO pin becomes serial data I/O (SISO) pin for the slave mode. The MISO pin in master mode and
MOSI pin in slave mode are not used by the SPI.
Table 14-9. Normal Mode and Bidirectional Mode
When SPE = 1
Master Mode MSTR = 1
Serial Out
Normal Mode
SPC0 = 0
Bidirectional Mode
SPC0 = 1
Slave Mode MSTR = 0
MOSI
Serial In
MOSI
SPI
SPI
Serial In
MISO
Serial Out
Serial Out
MOMI
Serial In
MISO
BIDIROE
SPI
Serial In
SPI
BIDIROE
Serial Out
SISO
MC9S12HZ256 Data Sheet, Rev. 2.04
436
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
The direction of each serial I/O pin depends on the BIDIROE bit. If the pin is configured as an output,
serial data from the shift register is driven out on the pin. The same pin is also the serial input to the shift
register.
The SCK is output for the master mode and input for the slave mode.
The SS is the input or output for the master mode, and it is always the input for the slave mode.
The bidirectional mode does not affect SCK and SS functions.
NOTE
In bidirectional master mode, with mode fault enabled, both data pins MISO
and MOSI can be occupied by the SPI, though MOSI is normally used for
transmissions in bidirectional mode and MISO is not used by the SPI. If a
mode fault occurs, the SPI is automatically switched to slave mode, in this
case MISO becomes occupied by the SPI and MOSI is not used. This has to
be considered, if the MISO pin is used for other purpose.
14.4.6
Error Conditions
The SPI has one error condition:
• Mode fault error
14.4.6.1
Mode Fault Error
If the SS input becomes low while the SPI is configured as a master, it indicates a system error where more
than one master may be trying to drive the MOSI and SCK lines simultaneously. This condition is not
permitted in normal operation, the MODF bit in the SPI Status Register is set automatically provided the
MODFEN bit is set.
In the special case where the SPI is in master mode and MODFEN bit is cleared, the SS pin is not used by
the SPI. In this special case, the mode fault error function is inhibited and MODF remains cleared. In case
the SPI system is configured as a slave, the SS pin is a dedicated input pin. Mode fault error doesn’t occur
in slave mode.
If a mode fault error occurs the SPI is switched to slave mode, with the exception that the slave output
buffer is disabled. So SCK, MISO and MOSI pins are forced to be high impedance inputs to avoid any
possibility of conflict with another output driver. A transmission in progress is aborted and the SPI is
forced into idle state.
If the mode fault error occurs in the bidirectional mode for a SPI system configured in master mode, output
enable of the MOMI (MOSI in bidirectional mode) is cleared if it was set. No mode fault error occurs in
the bidirectional mode for SPI system configured in slave mode.
The mode fault flag is cleared automatically by a read of the SPI Status Register (with MODF set) followed
by a write to SPI Control Register 1. If the mode fault flag is cleared, the SPI becomes a normal master or
slave again.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
437
Chapter 14 Serial Peripheral Interface (SPIV3)
14.4.7
Operation in Run Mode
In run mode with the SPI system enable (SPE) bit in the SPI control register clear, the SPI system is in a
low-power, disabled state. SPI registers remain accessible, but clocks to the core of this module are
disabled.
14.4.8
Operation in Wait Mode
SPI operation in wait mode depends upon the state of the SPISWAI bit in SPI Control Register 2.
• If SPISWAI is clear, the SPI operates normally when the CPU is in wait mode
• If SPISWAI is set, SPI clock generation ceases and the SPI module enters a power conservation
state when the CPU is in wait mode.
— If SPISWAI is set and the SPI is configured for master, any transmission and reception in
progress stops at wait mode entry. The transmission and reception resumes when the SPI exits
wait mode.
— If SPISWAI is set and the SPI is configured as a slave, any transmission and reception in
progress continues if the SCK continues to be driven from the master. This keeps the slave
synchronized to the master and the SCK.
If the master transmits several bytes while the slave is in wait mode, the slave will continue to
send out bytes consistent with the operation mode at the start of wait mode (i.e. If the slave is
currently sending its SPIDR to the master, it will continue to send the same byte. Else if the
slave is currently sending the last received byte from the master, it will continue to send each
previous master byte).
NOTE
Care must be taken when expecting data from a master while the slave is in
wait or stop mode. Even though the shift register will continue to operate,
the rest of the SPI is shut down (i.e. a SPIF interrupt will not be generated
until exiting stop or wait mode). Also, the byte from the shift register will
not be copied into the SPIDR register until after the slave SPI has exited wait
or stop mode. A SPIF flag and SPIDR copy is only generated if wait mode
is entered or exited during a tranmission. If the slave enters wait mode in idle
mode and exits wait mode in idle mode, neither a SPIF nor a SPIDR copy
will occur.
14.4.9
Operation in Stop Mode
Stop mode is dependent on the system. The SPI enters stop mode when the module clock is disabled (held
high or low). If the SPI is in master mode and exchanging data when the CPU enters stop mode, the
transmission is frozen until the CPU exits stop mode. After stop, data to and from the external SPI is
exchanged correctly. In slave mode, the SPI will stay synchronized with the master.
The stop mode is not dependent on the SPISWAI bit.
MC9S12HZ256 Data Sheet, Rev. 2.04
438
Freescale Semiconductor
Chapter 14 Serial Peripheral Interface (SPIV3)
14.5
Reset
The reset values of registers and signals are described in the Memory Map and Registers section (see
Section 14.3, “Memory Map and Register Definition”) which details the registers and their bit-fields.
• If a data transmission occurs in slave mode after reset without a write to SPIDR, it will transmit
garbage, or the byte last received from the master before the reset.
• Reading from the SPIDR after reset will always read a byte of zeros.
14.6
Interrupts
The SPI only originates interrupt requests when SPI is enabled (SPE bit in SPICR1 set). The following is
a description of how the SPI makes a request and how the MCU should acknowledge that request. The
interrupt vector offset and interrupt priority are chip dependent.
The interrupt flags MODF, SPIF and SPTEF are logically ORed to generate an interrupt request.
14.6.1
MODF
MODF occurs when the master detects an error on the SS pin. The master SPI must be configured for the
MODF feature (see Table 14-3). After MODF is set, the current transfer is aborted and the following bit is
changed:
• MSTR = 0, The master bit in SPICR1 resets.
The MODF interrupt is reflected in the status register MODF flag. Clearing the flag will also clear the
interrupt. This interrupt will stay active while the MODF flag is set. MODF has an automatic clearing
process which is described in Section 14.3.2.4, “SPI Status Register (SPISR).”
14.6.2
SPIF
SPIF occurs when new data has been received and copied to the SPI Data Register. After SPIF is set, it
does not clear until it is serviced. SPIF has an automatic clearing process which is described in
Section 14.3.2.4, “SPI Status Register (SPISR).” In the event that the SPIF is not serviced before the end
of the next transfer (i.e. SPIF remains active throughout another transfer), the latter transfers will be
ignored and no new data will be copied into the SPIDR.
14.6.3
SPTEF
SPTEF occurs when the SPI Data Register is ready to accept new data. After SPTEF is set, it does not clear
until it is serviced. SPTEF has an automatic clearing process which is described in Section 14.3.2.4, “SPI
Status Register (SPISR).”
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
439
Chapter 14 Serial Peripheral Interface (SPIV3)
MC9S12HZ256 Data Sheet, Rev. 2.04
440
Freescale Semiconductor
Chapter 15
Pulse-Width Modulator (PWM8B6CV1)
15.1
Introduction
The pulse width modulation (PWM) definition is based on the HC12 PWM definitions. The PWM8B6C
module contains the basic features from the HC11 with some of the enhancements incorporated on the
HC12, that is center aligned output mode and four available clock sources. The PWM8B6C module has
six channels with independent control of left and center aligned outputs on each channel.
Each of the six PWM channels has a programmable period and duty cycle as well as a dedicated counter.
A flexible clock select scheme allows a total of four different clock sources to be used with the counters.
Each of the modulators can create independent continuous waveforms with software-selectable duty rates
from 0% to 100%. The PWM outputs can be programmed as left aligned outputs or center aligned outputs
15.1.1
•
•
•
•
•
•
•
•
•
•
Features
Six independent PWM channels with programmable period and duty cycle
Dedicated counter for each PWM channel
Programmable PWM enable/disable for each channel
Software selection of PWM duty pulse polarity for each channel
Period and duty cycle are double buffered. Change takes effect when the end of the effective period
is reached (PWM counter reaches 0) or when the channel is disabled.
Programmable center or left aligned outputs on individual channels
Six 8-bit channel or three 16-bit channel PWM resolution
Four clock sources (A, B, SA, and SB) provide for a wide range of frequencies.
Programmable clock select logic
Emergency shutdown
15.1.2
Modes of Operation
There is a software programmable option for low power consumption in wait mode that disables the input
clock to the prescaler.
In freeze mode there is a software programmable option to disable the input clock to the prescaler. This is
useful for emulation.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
441
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.1.3
Block Diagram
PWM8B6C
PWM Channels
Channel 5
Bus Clock
Clock Select
PWM Clock
Period and Duty
PWM5
Counter
Channel 4
Period and Duty
PWM4
Counter
Control
Channel 3
Period and Duty
PWM3
Counter
Channel 2
Enable
Period and Duty
PWM2
Counter
Channel 1
Polarity
Period and Duty
Alignment
PWM1
Counter
Channel 0
Period and Duty
PWM0
Counter
Figure 15-1. PWM8B6C Block Diagram
15.2
External Signal Description
The PWM8B6C module has a total of six external pins.
15.2.1
PWM5 — Pulse Width Modulator Channel 5 Pin
This pin serves as waveform output of PWM channel 5 and as an input for the emergency shutdown
feature.
15.2.2
PWM4 — Pulse Width Modulator Channel 4 Pin
This pin serves as waveform output of PWM channel 4.
15.2.3
PWM3 — Pulse Width Modulator Channel 3 Pin
This pin serves as waveform output of PWM channel 3.
MC9S12HZ256 Data Sheet, Rev. 2.04
442
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.2.4
PWM2 — Pulse Width Modulator Channel 2 Pin
This pin serves as waveform output of PWM channel 2.
15.2.5
PWM1 — Pulse Width Modulator Channel 1 Pin
This pin serves as waveform output of PWM channel 1.
15.2.6
PWM0 — Pulse Width Modulator Channel 0 Pin
This pin serves as waveform output of PWM channel 0.
15.3
Memory Map and Register Definition
This subsection describes in detail all the registers and register bits in the PWM8B6C module.
The special-purpose registers and register bit functions that would not normally be made available to
device end users, such as factory test control registers and reserved registers are clearly identified by means
of shading the appropriate portions of address maps and register diagrams. Notes explaining the reasons
for restricting access to the registers and functions are also explained in the individual register descriptions.
15.3.1
Module Memory Map
The following paragraphs describe the content of the registers in the PWM8B6C module. The base address
of the PWM8B6C module is determined at the MCU level when the MCU is defined. The register decode
map is fixed and begins at the first address of the module address offset. Table 15-1 shows the registers
associated with the PWM and their relative offset from the base address. The register detail description
follows the order in which they appear in the register map.
Reserved bits within a register will always read as 0 and the write will be unimplemented. Unimplemented
functions are indicated by shading the bit.
Table 15-1 shows the memory map for the PWM8B6C module.
NOTE
Register address = base address + address offset, where the base address is
defined at the MCU level and the address offset is defined at the module
level.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
443
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-1. PWM8B6C Memory Map
Address
Offset
Register
Access
0x0000
PWM Enable Register (PWME)
R/W
0x0001
PWM Polarity Register (PWMPOL)
R/W
0x0002
PWM Clock Select Register (PWMCLK)
R/W
0x0003
PWM Prescale Clock Select Register (PWMPRCLK)
R/W
0x0004
PWM Center Align Enable Register (PWMCAE)
R/W
0x0005
PWM Control Register (PWMCTL)
R/W
0x0006
1
PWM Test Register (PWMTST)
R/W
2
0x0007
PWM Prescale Counter Register (PWMPRSC)
R/W
0x0008
PWM Scale A Register (PWMSCLA)
R/W
0x0009
PWM Scale B Register (PWMSCLB)
R/W
PWM Scale A Counter Register
(PWMSCNTA)3
R/W
0x000B
PWM Scale B Counter Register
(PWMSCNTB)4
R/W
0x000C
PWM Channel 0 Counter Register (PWMCNT0)
R/W
0x000D
PWM Channel 1 Counter Register (PWMCNT1)
R/W
0x000E
PWM Channel 2 Counter Register (PWMCNT2)
R/W
0x000F
PWM Channel 3 Counter Register (PWMCNT3)
R/W
0x0010
PWM Channel 4 Counter Register (PWMCNT4)
R/W
0x0011
PWM Channel 5 Counter Register (PWMCNT5)
R/W
0x0012
PWM Channel 0 Period Register (PWMPER0)
R/W
0x0013
PWM Channel 1 Period Register (PWMPER1)
R/W
0x0014
PWM Channel 2 Period Register (PWMPER2)
R/W
0x0015
PWM Channel 3 Period Register (PWMPER3)
R/W
0x0016
PWM Channel 4 Period Register (PWMPER4)
R/W
0x0017
PWM Channel 5 Period Register (PWMPER5)
R/W
0x0018
PWM Channel 0 Duty Register (PWMDTY0)
R/W
0x0019
PWM Channel 1 Duty Register (PWMDTY1)
R/W
0x001A
PWM Channel 2 Duty Register (PWMDTY2)
R/W
0x001B
PWM Channel 3 Duty Register (PWMDTY3)
R/W
0x001C
PWM Channel 4 Duty Register (PWMDTY4)
R/W
0x001D
PWM Channel 5 Duty Register (PWMDTY5)
R/W
0x001E
PWM Shutdown Register (PWMSDN)
R/W
0x000A
1
PWMTST is intended for factory test purposes only.
PWMPRSC is intended for factory test purposes only.
3 PWMSCNTA is intended for factory test purposes only.
4
PWMSCNTB is intended for factory test purposes only.
2
MC9S12HZ256 Data Sheet, Rev. 2.04
444
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2
Register Descriptions
The following paragraphs describe in detail all the registers and register bits in the PWM8B6C module.
Register
Name
Bit 7
6
5
4
3
2
1
Bit 0
PWME5
PWME4
PWME3
PWME2
PWME1
PWME0
PPOL5
PPOL4
PPOL3
PPOL2
PPOL1
PPOL0
PCLK5
PCLK4
PCLK3
PCLK2
PCLK1
PCLK0
PCKB1
PCKB0
PCKA2
PCKA1
PCKA0
CAE5
CAE4
CAE2
CAE2
CAE1
CAE0
CON45
CON23
CON01
PSWAI
PFRZ
0
0
PWME
R
W
0
0
PWMPOL
R
W
0
0
PWMCLK
R
W
0
0
PWMPRCLK
R
W
0
PWMCAE
R
W
0
PWMCTL
R
W
0
PWMTST
R
W
0
0
0
0
0
0
0
0
PWMPRSC
R
W
0
0
0
0
0
0
0
0
PWMSCLA
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMSCLB
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMSCNTA
R
W
0
0
0
0
0
0
0
0
PWMSCNTB
R
W
0
0
0
0
0
0
0
0
PWMCNT0
R
W
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
PWMCNT1
R
W
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
PWMCNT2
R
W
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
PCKB2
0
0
= Unimplemented or Reserved
Figure 15-2. PWM Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
445
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Register
Name
Bit 7
6
5
4
3
2
1
Bit 0
PWMCNT3
R
W
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
PWMCNT4
R
W
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
PWMCNT5
R
W
Bit 7
0
6
0
5
0
4
0
3
0
2
0
1
0
Bit 0
0
PWMPER0
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER1
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER2
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER3
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER4
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER5
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMDTY0
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER1
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER2
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER3
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER4
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMPER5
R
W
Bit 7
6
5
4
3
2
1
Bit 0
PWMSDB
R
W
PWMIF
PWMIE
0
PWMRSTRT
PWMLVL
0
PWM5IN
PWM5INL PWM5ENA
= Unimplemented or Reserved
Figure 15-2. PWM Register Summary (continued)
MC9S12HZ256 Data Sheet, Rev. 2.04
446
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2.1
PWM Enable Register (PWME)
Each PWM channel has an enable bit (PWMEx) to start its waveform output. When any of the PWMEx
bits are set (PWMEx = 1), the associated PWM output is enabled immediately. However, the actual PWM
waveform is not available on the associated PWM output until its clock source begins its next cycle due to
the synchronization of PWMEx and the clock source.
NOTE
The first PWM cycle after enabling the channel can be irregular.
An exception to this is when channels are concatenated. After concatenated mode is enabled (CONxx bits
set in PWMCTL register), enabling/disabling the corresponding 16-bit PWM channel is controlled by the
low-order PWMEx bit. In this case, the high-order bytes PWMEx bits have no effect and their
corresponding PWM output lines are disabled.
While in run mode, if all six PWM channels are disabled (PWME5–PWME0 = 0), the prescaler counter
shuts off for power savings.
R
7
6
0
0
5
4
3
2
1
0
PWME5
PWME4
PWME3
PWME2
PWME1
PWME0
0
0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 15-3. PWM Enable Register (PWME)
Read: anytime
Write: anytime
Table 15-2. PWME Field Descriptions
Field
Description
5
PWME5
Pulse Width Channel 5 Enable
0 Pulse width channel 5 is disabled.
1 Pulse width channel 5 is enabled. The pulse modulated signal becomes available at PWM,output bit 5 when
its clock source begins its next cycle.
4
PWME4
Pulse Width Channel 4 Enable
0 Pulse width channel 4 is disabled.
1 Pulse width channel 4 is enabled. The pulse modulated signal becomes available at PWM, output bit 4 when
its clock source begins its next cycle. If CON45 = 1, then bit has no effect and PWM output line 4 is disabled.
3
PWME3
Pulse Width Channel 3 Enable
0 Pulse width channel 3 is disabled.
1 Pulse width channel 3 is enabled. The pulse modulated signal becomes available at PWM, output bit 3 when
its clock source begins its next cycle.
2
PWME2
Pulse Width Channel 2 Enable
0 Pulse width channel 2 is disabled.
1 Pulse width channel 2 is enabled. The pulse modulated signal becomes available at PWM, output bit 2 when
its clock source begins its next cycle. If CON23 = 1, then bit has no effect and PWM output line 2 is disabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
447
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-2. PWME Field Descriptions (continued)
Field
Description
1
PWME1
Pulse Width Channel 1 Enable
0 Pulse width channel 1 is disabled.
1 Pulse width channel 1 is enabled. The pulse modulated signal becomes available at PWM, output bit 1 when
its clock source begins its next cycle.
0
PWME0
Pulse Width Channel 0 Enable
0 Pulse width channel 0 is disabled.
1 Pulse width channel 0 is enabled. The pulse modulated signal becomes available at PWM, output bit 0 when
its clock source begins its next cycle. If CON01 = 1, then bit has no effect and PWM output line 0 is disabled.
15.3.2.2
PWM Polarity Register (PWMPOL)
The starting polarity of each PWM channel waveform is determined by the associated PPOLx bit in the
PWMPOL register. If the polarity bit is 1, the PWM channel output is high at the beginning of the cycle
and then goes low when the duty count is reached. Conversely, if the polarity bit is 0 the output starts low
and then goes high when the duty count is reached.
R
7
6
0
0
5
4
3
2
1
0
PPOL5
PPOL4
PPOL3
PPOL2
PPOL1
PPOL0
0
0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 15-4. PWM Polarity Register (PWMPOL)
Read: anytime
Write: anytime
NOTE
PPOLx register bits can be written anytime. If the polarity is changed while
a PWM signal is being generated, a truncated or stretched pulse can occur
during the transition
Table 15-3. PWMPOL Field Descriptions
Field
Description
5
PPOL5
Pulse Width Channel 5 Polarity
0 PWM channel 5 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 5 output is high at the beginning of the period, then goes low when the duty count is reached.
4
PPOL4
Pulse Width Channel 4 Polarity
0 PWM channel 4 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 4 output is high at the beginning of the period, then goes low when the duty count is reached.
3
PPOL3
Pulse Width Channel 3 Polarity
0 PWM channel 3 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 3 output is high at the beginning of the period, then goes low when the duty count is reached.
MC9S12HZ256 Data Sheet, Rev. 2.04
448
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-3. PWMPOL Field Descriptions (continued)
Field
Description
2
PPOL2
Pulse Width Channel 2 Polarity
0 PWM channel 2 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 2 output is high at the beginning of the period, then goes low when the duty count is reached.
1
PPOL1
Pulse Width Channel 1 Polarity
0 PWM channel 1 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 1 output is high at the beginning of the period, then goes low when the duty count is reached.
0
PPOL0
Pulse Width Channel 0 Polarity
0 PWM channel 0 output is low at the beginning of the period, then goes high when the duty count is reached
1 PWM channel 0 output is high at the beginning of the period, then goes low when the duty count is reached.
15.3.2.3
PWM Clock Select Register (PWMCLK)
Each PWM channel has a choice of two clocks to use as the clock source for that channel as described
below.
R
7
6
0
0
5
4
3
2
1
0
PCLK5
PCLK4
PCLK3
PCLK2
PCLK1
PCLK0
0
0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 15-5. PWM Clock Select Register (PWMCLK)
Read: anytime
Write: anytime
NOTE
Register bits PCLK0 to PCLK5 can be written anytime. If a clock select is
changed while a PWM signal is being generated, a truncated or stretched
pulse can occur during the transition.
Table 15-4. PWMCLK Field Descriptions
Field
Description
5
PCLK5
Pulse Width Channel 5 Clock Select
0 Clock A is the clock source for PWM channel 5.
1 Clock SA is the clock source for PWM channel 5.
4
PCLK4
Pulse Width Channel 4 Clock Select
0 Clock A is the clock source for PWM channel 4.
1 Clock SA is the clock source for PWM channel 4.
3
PCLK3
Pulse Width Channel 3 Clock Select
0 Clock B is the clock source for PWM channel 3.
1 Clock SB is the clock source for PWM channel 3.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
449
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-4. PWMCLK Field Descriptions (continued)
Field
Description
2
PCLK2
Pulse Width Channel 2 Clock Select
0 Clock B is the clock source for PWM channel 2.
1 Clock SB is the clock source for PWM channel 2.
1
PCLK1
Pulse Width Channel 1 Clock Select
0 Clock A is the clock source for PWM channel 1.
1 Clock SA is the clock source for PWM channel 1.
0
PCLK0
Pulse Width Channel 0 Clock Select
0 Clock A is the clock source for PWM channel 0.
1 Clock SA is the clock source for PWM channel 0.
15.3.2.4
PWM Prescale Clock Select Register (PWMPRCLK)
This register selects the prescale clock source for clocks A and B independently.
7
R
6
5
4
3
0
2
1
0
PCKA2
PCKA1
PCKA0
0
0
0
0
PCKB2
PCKB1
PCKB0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 15-6. PWM Prescaler Clock Select Register (PWMPRCLK)
Read: anytime
Write: anytime
NOTE
PCKB2–PCKB0 and PCKA2–PCKA0 register bits can be written anytime.
If the clock prescale is changed while a PWM signal is being generated, a
truncated or stretched pulse can occur during the transition.
Table 15-5. PWMPRCLK Field Descriptions
Field
Description
6:5
PCKB[2:0]
Prescaler Select for Clock B — Clock B is 1 of two clock sources which can be used for channels 2 or 3. These
three bits determine the rate of clock B, as shown in Table 15-6.
2:0
PCKA[2:0]
Prescaler Select for Clock A — Clock A is 1 of two clock sources which can be used for channels 0, 1, 4, or 5.
These three bits determine the rate of clock A, as shown in Table 15-7.
MC9S12HZ256 Data Sheet, Rev. 2.04
450
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-6. Clock B Prescaler Selects
PCKB2
PCKB1
PCKB0
Value of Clock B
0
0
0
Bus Clock
0
0
1
Bus Clock / 2
0
1
0
Bus Clock / 4
0
1
1
Bus Clock / 8
1
0
0
Bus Clock / 16
1
0
1
Bus Clock / 32
1
1
0
Bus Clock / 64
1
1
1
Bus Clock / 128
Table 15-7. Clock A Prescaler Selects
15.3.2.5
PCKA2
PCKA1
PCKA0
Value of Clock A
0
0
0
Bus Clock
0
0
1
Bus Clock / 2
0
1
0
Bus Clock / 4
0
1
1
Bus Clock / 8
1
0
0
Bus Clock / 16
1
0
1
Bus Clock / 32
1
1
0
Bus Clock / 64
1
1
1
Bus Clock / 128
PWM Center Align Enable Register (PWMCAE)
The PWMCAE register contains six control bits for the selection of center aligned outputs or left aligned
outputs for each PWM channel. If the CAEx bit is set to a 1, the corresponding PWM output will be center
aligned. If the CAEx bit is cleared, the corresponding PWM output will be left aligned. Reference
Section 15.4.2.5, “Left Aligned Outputs,” and Section 15.4.2.6, “Center Aligned Outputs,” for a more
detailed description of the PWM output modes.
R
7
6
0
0
5
4
3
2
1
0
CAE5
CAE4
CAE3
CAE2
CAE1
CAE0
0
0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 15-7. PWM Center Align Enable Register (PWMCAE)
Read: anytime
Write: anytime
NOTE
Write these bits only when the corresponding channel is disabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
451
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-8. PWMCAE Field Descriptions
Field
Description
5
CAE5
Center Aligned Output Mode on Channel 5
0 Channel 5 operates in left aligned output mode.
1 Channel 5 operates in center aligned output mode.
4
CAE4
Center Aligned Output Mode on Channel 4
0 Channel 4 operates in left aligned output mode.
1 Channel 4 operates in center aligned output mode.
3
CAE3
Center Aligned Output Mode on Channel 3
1 Channel 3 operates in left aligned output mode.
1 Channel 3 operates in center aligned output mode.
2
CAE2
Center Aligned Output Mode on Channel 2
0 Channel 2 operates in left aligned output mode.
1 Channel 2 operates in center aligned output mode.
1
CAE1
Center Aligned Output Mode on Channel 1
0 Channel 1 operates in left aligned output mode.
1 Channel 1 operates in center aligned output mode.
0
CAE0
Center Aligned Output Mode on Channel 0
0 Channel 0 operates in left aligned output mode.
1 Channel 0 operates in center aligned output mode.
15.3.2.6
PWM Control Register (PWMCTL)
The PWMCTL register provides for various control of the PWM module.
7
R
6
5
4
3
2
CON45
CON23
CON01
PSWAI
PFRZ
0
0
0
0
0
0
1
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 15-8. PWM Control Register (PWMCTL)
Read: anytime
Write: anytime
There are three control bits for concatenation, each of which is used to concatenate a pair of PWM
channels into one 16-bit channel. When channels 4 and 5 are concatenated, channel 4 registers become the
high-order bytes of the double-byte channel. When channels 2 and 3 are concatenated, channel 2 registers
become the high-order bytes of the double-byte channel. When channels 0 and 1 are concatenated,
channel 0 registers become the high-order bytes of the double-byte channel.
Reference Section 15.4.2.7, “PWM 16-Bit Functions,” for a more detailed description of the concatenation
PWM function.
MC9S12HZ256 Data Sheet, Rev. 2.04
452
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
NOTE
Change these bits only when both corresponding channels are disabled.
Table 15-9. PWMCTL Field Descriptions
Field
Description
6
CON45
Concatenate Channels 4 and 5
0 Channels 4 and 5 are separate 8-bit PWMs.
1 Channels 4 and 5 are concatenated to create one 16-bit PWM channel. Channel 4 becomes the high-order
byte and channel 5 becomes the low-order byte. Channel 5 output pin is used as the output for this 16-bit PWM
(bit 5 of port PWMP). Channel 5 clock select control bit determines the clock source, channel 5 polarity bit
determines the polarity, channel 5 enable bit enables the output and channel 5 center aligned enable bit
determines the output mode.
5
CON23
Concatenate Channels 2 and 3
0 Channels 2 and 3 are separate 8-bit PWMs.
1 Channels 2 and 3 are concatenated to create one 16-bit PWM channel. Channel 2 becomes the high-order
byte and channel 3 becomes the low-order byte. Channel 3 output pin is used as the output for this 16-bit PWM
(bit 3 of port PWMP). Channel 3 clock select control bit determines the clock source, channel 3 polarity bit
determines the polarity, channel 3 enable bit enables the output and channel 3 center aligned enable bit
determines the output mode.
4
CON01
Concatenate Channels 0 and 1
0 Channels 0 and 1 are separate 8-bit PWMs.
1 Channels 0 and 1 are concatenated to create one 16-bit PWM channel. Channel 0 becomes the high-order
byte and channel 1 becomes the low-order byte. Channel 1 output pin is used as the output for this 16-bit PWM
(bit 1 of port PWMP). Channel 1 clock select control bit determines the clock source, channel 1 polarity bit
determines the polarity, channel 1 enable bit enables the output and channel 1 center aligned enable bit
determines the output mode.
3
PSWAI
PWM Stops in Wait Mode — Enabling this bit allows for lower power consumption in wait mode by disabling the
input clock to the prescaler.
0 Allow the clock to the prescaler to continue while in wait mode.
1 Stop the input clock to the prescaler whenever the MCU is in wait mode.
2
PFRZ
PWM Counters Stop in Freeze Mode — In freeze mode, there is an option to disable the input clock to the
prescaler by setting the PFRZ bit in the PWMCTL register. If this bit is set, whenever the MCU is in freeze mode
the input clock to the prescaler is disabled. This feature is useful during emulation as it allows the PWM function
to be suspended. In this way, the counters of the PWM can be stopped while in freeze mode so that after normal
program flow is continued, the counters are re-enabled to simulate real-time operations. Because the registers
remain accessible in this mode, to re-enable the prescaler clock, either disable the PFRZ bit or exit freeze mode.
0 Allow PWM to continue while in freeze mode.
1 Disable PWM input clock to the prescaler whenever the part is in freeze mode. This is useful for emulation.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
453
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2.7
Reserved Register (PWMTST)
This register is reserved for factory testing of the PWM module and is not available in normal modes.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 15-9. Reserved Register (PWMTST)
Read: always read 0x0000 in normal modes
Write: unimplemented in normal modes
NOTE
Writing to this register when in special modes can alter the PWM
functionality.
15.3.2.8
Reserved Register (PWMPRSC)
This register is reserved for factory testing of the PWM module and is not available in normal modes.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 15-10. Reserved Register (PWMPRSC)
Read: always read 0x0000 in normal modes
Write: unimplemented in normal modes
NOTE
Writing to this register when in special modes can alter the PWM
functionality.
MC9S12HZ256 Data Sheet, Rev. 2.04
454
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2.9
PWM Scale A Register (PWMSCLA)
PWMSCLA is the programmable scale value used in scaling clock A to generate clock SA. Clock SA is
generated by taking clock A, dividing it by the value in the PWMSCLA register and dividing that by two.
Clock SA = Clock A / (2 * PWMSCLA)
NOTE
When PWMSCLA = 0x0000, PWMSCLA value is considered a full scale
value of 256. Clock A is thus divided by 512.
Any value written to this register will cause the scale counter to load the new scale value (PWMSCLA).
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-11. PWM Scale A Register (PWMSCLA)
Read: anytime
Write: anytime (causes the scale counter to load the PWMSCLA value)
15.3.2.10 PWM Scale B Register (PWMSCLB)
PWMSCLB is the programmable scale value used in scaling clock B to generate clock SB. Clock SB is
generated by taking clock B, dividing it by the value in the PWMSCLB register and dividing that by two.
Clock SB = Clock B / (2 * PWMSCLB)
NOTE
When PWMSCLB = 0x0000, PWMSCLB value is considered a full scale
value of 256. Clock B is thus divided by 512.
Any value written to this register will cause the scale counter to load the new scale value (PWMSCLB).
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-12. PWM Scale B Register (PWMSCLB)
Read: anytime
Write: anytime (causes the scale counter to load the PWMSCLB value).
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
455
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2.11 Reserved Registers (PWMSCNTx)
The registers PWMSCNTA and PWMSCNTB are reserved for factory testing of the PWM module and
are not available in normal modes.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 15-13. Reserved Register (PWMSCNTA)
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 15-14. Reserved Register (PWMSCNTB)
Read: always read 0x0000 in normal modes
Write: unimplemented in normal modes
NOTE
Writing to these registers when in special modes can alter the PWM
functionality.
MC9S12HZ256 Data Sheet, Rev. 2.04
456
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2.12 PWM Channel Counter Registers (PWMCNTx)
Each channel has a dedicated 8-bit up/down counter which runs at the rate of the selected clock source.
The counter can be read at any time without affecting the count or the operation of the PWM channel. In
left aligned output mode, the counter counts from 0 to the value in the period register – 1. In center aligned
output mode, the counter counts from 0 up to the value in the period register and then back down to 0.
Any value written to the counter causes the counter to reset to 0x0000, the counter direction to be set to
up, the immediate load of both duty and period registers with values from the buffers, and the output to
change according to the polarity bit. The counter is also cleared at the end of the effective period (see
Section 15.4.2.5, “Left Aligned Outputs,” and Section 15.4.2.6, “Center Aligned Outputs,” for more
details). When the channel is disabled (PWMEx = 0), the PWMCNTx register does not count. When a
channel becomes enabled (PWMEx = 1), the associated PWM counter starts at the count in the
PWMCNTx register. For more detailed information on the operation of the counters, reference
Section 15.4.2.4, “PWM Timer Counters.”
In concatenated mode, writes to the 16-bit counter by using a 16-bit access or writes to either the low- or
high-order byte of the counter will reset the 16-bit counter. Reads of the 16-bit counter must be made by
16-bit access to maintain data coherency.
NOTE
Writing to the counter while the channel is enabled can cause an irregular
PWM cycle to occur.
7
6
5
4
3
2
1
0
R
Bit 7
6
5
4
3
2
1
Bit 0
W
0
0
0
0
0
0
0
0
Reset
0
0
0
0
0
0
0
0
Figure 15-15. PWM Channel Counter Registers (PWMCNT0)
7
6
5
4
3
2
1
0
R
Bit 7
6
5
4
3
2
1
Bit 0
W
0
0
0
0
0
0
0
0
Reset
0
0
0
0
0
0
0
0
Figure 15-16. PWM Channel Counter Registers (PWMCNT1)
7
6
5
4
3
2
1
0
R
Bit 7
6
5
4
3
2
1
Bit 0
W
0
0
0
0
0
0
0
0
Reset
0
0
0
0
0
0
0
0
Figure 15-17. PWM Channel Counter Registers (PWMCNT2)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
457
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
7
6
5
4
3
2
1
0
R
Bit 7
6
5
4
3
2
1
Bit 0
W
0
0
0
0
0
0
0
0
Reset
0
0
0
0
0
0
0
0
Figure 15-18. PWM Channel Counter Registers (PWMCNT3)
7
6
5
4
3
2
1
0
R
Bit 7
6
5
4
3
2
1
Bit 0
W
0
0
0
0
0
0
0
0
Reset
0
0
0
0
0
0
0
0
Figure 15-19. PWM Channel Counter Registers (PWMCNT4)
7
6
5
4
3
2
1
0
R
Bit 7
6
5
4
3
2
1
Bit 0
W
0
0
0
0
0
0
0
0
Reset
0
0
0
0
0
0
0
0
Figure 15-20. PWM Channel Counter Registers (PWMCNT5)
Read: anytime
Write: anytime (any value written causes PWM counter to be reset to 0x0000).
15.3.2.13 PWM Channel Period Registers (PWMPERx)
There is a dedicated period register for each channel. The value in this register determines the period of
the associated PWM channel.
The period registers for each channel are double buffered so that if they change while the channel is
enabled, the change will NOT take effect until one of the following occurs:
• The effective period ends
• The counter is written (counter resets to 0x0000)
• The channel is disabled
In this way, the output of the PWM will always be either the old waveform or the new waveform, not some
variation in between. If the channel is not enabled, then writes to the period register will go directly to the
latches as well as the buffer.
NOTE
Reads of this register return the most recent value written. Reads do not
necessarily return the value of the currently active period due to the double
buffering scheme.
Reference Section 15.4.2.3, “PWM Period and Duty,” for more information.
MC9S12HZ256 Data Sheet, Rev. 2.04
458
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
To calculate the output period, take the selected clock source period for the channel of interest (A, B, SA,
or SB) and multiply it by the value in the period register for that channel:
• Left aligned output (CAEx = 0)
• PWMx period = channel clock period * PWMPERx center aligned output (CAEx = 1)
• PWMx period = channel clock period * (2 * PWMPERx)
For boundary case programming values, please refer to Section 15.4.2.8, “PWM Boundary Cases.”
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-21. PWM Channel Period Registers (PWMPER0)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-22. PWM Channel Period Registers (PWMPER1)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-23. PWM Channel Period Registers (PWMPER2)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-24. PWM Channel Period Registers (PWMPER3)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-25. PWM Channel Period Registers (PWMPER4)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
459
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-26. PWM Channel Period Registers (PWMPER5)
Read: anytime
Write: anytime
15.3.2.14 PWM Channel Duty Registers (PWMDTYx)
There is a dedicated duty register for each channel. The value in this register determines the duty of the
associated PWM channel. The duty value is compared to the counter and if it is equal to the counter value
a match occurs and the output changes state.
The duty registers for each channel are double buffered so that if they change while the channel is enabled,
the change will NOT take effect until one of the following occurs:
• The effective period ends
• The counter is written (counter resets to 0x0000)
• The channel is disabled
In this way, the output of the PWM will always be either the old duty waveform or the new duty waveform,
not some variation in between. If the channel is not enabled, then writes to the duty register will go directly
to the latches as well as the buffer.
NOTE
Reads of this register return the most recent value written. Reads do not
necessarily return the value of the currently active duty due to the double
buffering scheme.
Reference Section 15.4.2.3, “PWM Period and Duty,” for more information.
NOTE
Depending on the polarity bit, the duty registers will contain the count of
either the high time or the low time. If the polarity bit is 1, the output starts
high and then goes low when the duty count is reached, so the duty registers
contain a count of the high time. If the polarity bit is 0, the output starts low
and then goes high when the duty count is reached, so the duty registers
contain a count of the low time.
To calculate the output duty cycle (high time as a % of period) for a particular channel:
• Polarity = 0 (PPOLx = 0)
Duty cycle = [(PWMPERx PWMDTYx)/PWMPERx] * 100%
• Polarity = 1 (PPOLx = 1)
Duty cycle = [PWMDTYx / PWMPERx] * 100%
• For boundary case programming values, please refer to Section 15.4.2.8, “PWM Boundary Cases.”
MC9S12HZ256 Data Sheet, Rev. 2.04
460
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 15-27. PWM Channel Duty Registers (PWMDTY0)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 15-28. PWM Channel Duty Registers (PWMDTY1)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 15-29. PWM Channel Duty Registers (PWMDTY2)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 15-30. PWM Channel Duty Registers (PWMDTY3)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 15-31. PWM Channel Duty Registers (PWMDTY4)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
1
1
1
1
1
1
1
1
R
W
Reset
Figure 15-32. PWM Channel Duty Registers (PWMDTY5)
Read: anytime
Write: anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
461
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.3.2.15 PWM Shutdown Register (PWMSDN)
The PWMSDN register provides for the shutdown functionality of the PWM module in the emergency
cases.
7
6
5
PWMIF
PWMIE
R
0
W
Reset
4
3
2
0
PWM5IN
PWMLVL
1
0
PWM5INL
PWM5ENA
0
0
PWMRSTRT
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 15-33. PWM Shutdown Register (PWMSDN)
Read: anytime
Write: anytime
Table 15-10. PWMSDN Field Descriptions
Field
Description
7
PWMIF
PWM Interrupt Flag — Any change from passive to asserted (active) state or from active to passive state will be
flagged by setting the PWMIF flag = 1. The flag is cleared by writing a logic 1 to it. Writing a 0 has no effect.
0 No change on PWM5IN input.
1 Change on PWM5IN input
6
PWMIE
PWM Interrupt Enable — If interrupt is enabled an interrupt to the CPU is asserted.
0 PWM interrupt is disabled.
1 PWM interrupt is enabled.
5
PWM Restart — The PWM can only be restarted if the PWM channel input 5 is deasserted. After writing a logic 1
PWMRSTRT to the PWMRSTRT bit (trigger event) the PWM channels start running after the corresponding counter passes
next “counter = 0” phase.
Also, if the PWM5ENA bit is reset to 0, the PWM do not start before the counter passes 0x0000.
The bit is always read as 0.
4
PWMLVL
PWM Shutdown Output Level — If active level as defined by the PWM5IN input, gets asserted all enabled PWM
channels are immediately driven to the level defined by PWMLVL.
0 PWM outputs are forced to 0
1 PWM outputs are forced to 1.
2
PWM5IN
PWM Channel 5 Input Status — This reflects the current status of the PWM5 pin.
1
PWM5INL
PWM Shutdown Active Input Level for Channel 5 — If the emergency shutdown feature is enabled
(PWM5ENA = 1), this bit determines the active level of the PWM5 channel.
0 Active level is low
1 Active level is high
0
PWM Emergency Shutdown Enable — If this bit is logic 1 the pin associated with channel 5 is forced to input
PWM5ENA and the emergency shutdown feature is enabled. All the other bits in this register are meaningful only if
PWM5ENA = 1.
0 PWM emergency feature disabled.
1 PWM emergency feature is enabled.
MC9S12HZ256 Data Sheet, Rev. 2.04
462
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.4
Functional Description
15.4.1
PWM Clock Select
There are four available clocks called clock A, clock B, clock SA (scaled A), and clock SB (scaled B).
These four clocks are based on the bus clock.
Clock A and B can be software selected to be 1, 1/2, 1/4, 1/8,..., 1/64, 1/128 times the bus clock. Clock SA
uses clock A as an input and divides it further with a reloadable counter. Similarly, clock SB uses clock B
as an input and divides it further with a reloadable counter. The rates available for clock SA are software
selectable to be clock A divided by 2, 4, 6, 8, ..., or 512 in increments of divide by 2. Similar rates are
available for clock SB. Each PWM channel has the capability of selecting one of two clocks, either the
pre-scaled clock (clock A or B) or the scaled clock (clock SA or SB).
The block diagram in Figure 15-34 shows the four different clocks and how the scaled clocks are created.
15.4.1.1
Prescale
The input clock to the PWM prescaler is the bus clock. It can be disabled whenever the part is in freeze
mode by setting the PFRZ bit in the PWMCTL register. If this bit is set, whenever the MCU is in freeze
mode the input clock to the prescaler is disabled. This is useful for emulation in order to freeze the PWM.
The input clock can also be disabled when all six PWM channels are disabled (PWME5–PWME0 = 0)
This is useful for reducing power by disabling the prescale counter.
Clock A and clock B are scaled values of the input clock. The value is software selectable for both clock A
and clock B and has options of 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, or 1/128 times the bus clock. The value
selected for clock A is determined by the PCKA2, PCKA1, and PCKA0 bits in the PWMPRCLK register.
The value selected for clock B is determined by the PCKB2, PCKB1, and PCKB0 bits also in the
PWMPRCLK register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
463
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Clock A
M
U
X
Clock to
PWM Ch 0
Clock A/2, A/4, A/6,....A/512
PCKA2
PCKA1
PCKA0
PCLK0
8-Bit Down Counter
Count = 1
M
U
X
Load
PWMSCLA
Clock SA
DIV 2
PCLK1
M
U
X
M
Clock to
PWM Ch 1
Clock to
PWM Ch 2
U
PCLK2
8 16 32 64 128
M
U
X
Clock B
4
M
U
X
Clock to
PWM Ch 4
Clock B/2, B/4, B/6,....B/512
PCLK4
M
U
8-Bit Down Counter
X
Count = 1
M
U
X
Load
PWMSCLB
Clock SB
PCLK5
PCKB2
PCKB1
PCKB0
DIV 2
Clock to
PWM Ch 5
PWME5:0
Bus Clock
PFRZ
FREEZE
Clock to
PWM Ch 3
PCLK3
2
Divide by Prescaler Taps:
X
PRESCALE
SCALE
CLOCK SELECT
Figure 15-34. PWM Clock Select Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
464
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.4.1.2
Clock Scale
The scaled A clock uses clock A as an input and divides it further with a user programmable value and
then divides this by 2. The scaled B clock uses clock B as an input and divides it further with a user
programmable value and then divides this by 2. The rates available for clock SA are software selectable
to be clock A divided by 2, 4, 6, 8, ..., or 512 in increments of divide by 2. Similar rates are available for
clock SB.
Clock A is used as an input to an 8-bit down counter. This down counter loads a user programmable scale
value from the scale register (PWMSCLA). When the down counter reaches 1, two things happen; a pulse
is output and the 8-bit counter is re-loaded. The output signal from this circuit is further divided by two.
This gives a greater range with only a slight reduction in granularity. Clock SA equals clock A divided by
two times the value in the PWMSCLA register.
NOTE
Clock SA = Clock A / (2 * PWMSCLA)
When PWMSCLA = 0x0000, PWMSCLA value is considered a full scale
value of 256. Clock A is thus divided by 512.
Similarly, clock B is used as an input to an 8-bit down counter followed by a divide by two producing clock
SB. Thus, clock SB equals clock B divided by two times the value in the PWMSCLB register.
NOTE
Clock SB = Clock B / (2 * PWMSCLB)
When PWMSCLB = 0x0000, PWMSCLB value is considered a full scale
value of 256. Clock B is thus divided by 512.
As an example, consider the case in which the user writes 0x00FF into the PWMSCLA register. Clock A
for this case will be bus clock divided by 4. A pulse will occur at a rate of once every 255 x 4 bus cycles.
Passing this through the divide by two circuit produces a clock signal at a bus clock divided by 2040 rate.
Similarly, a value of 0x0001 in the PWMSCLA register when clock A is bus clock divided by 4 will
produce a bus clock divided by 8 rate.
Writing to PWMSCLA or PWMSCLB causes the associated 8-bit down counter to be re-loaded.
Otherwise, when changing rates the counter would have to count down to 0x0001 before counting at the
proper rate. Forcing the associated counter to re-load the scale register value every time PWMSCLA or
PWMSCLB is written prevents this.
NOTE
Writing to the scale registers while channels are operating can cause
irregularities in the PWM outputs.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
465
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.4.1.3
Clock Select
Each PWM channel has the capability of selecting one of two clocks. For channels 0, 1, 4, and 5 the clock
choices are clock A or clock SA. For channels 2 and 3 the choices are clock B or clock SB. The clock
selection is done with the PCLKx control bits in the PWMCLK register.
NOTE
Changing clock control bits while channels are operating can cause
irregularities in the PWM outputs.
15.4.2
PWM Channel Timers
The main part of the PWM module are the actual timers. Each of the timer channels has a counter, a period
register and a duty register (each are 8 bit). The waveform output period is controlled by a match between
the period register and the value in the counter. The duty is controlled by a match between the duty register
and the counter value and causes the state of the output to change during the period. The starting polarity
of the output is also selectable on a per channel basis. Figure 15-35 shows a block diagram for PWM timer.
Clock Source
From Port PWMP
Data Register
8-Bit Counter
GATE
PWMCNTx
(clock edge sync)
8-Bit Compare =
up/down reset
T
Q
PWMDTYx
Q
M
U
X
M
U
X
R
To Pin
Driver
8-Bit Compare =
PWMPERx
PPOLx
Q
T
CAEx
Q
R
PWMEx
Figure 15-35. PWM Timer Channel Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
466
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.4.2.1
PWM Enable
Each PWM channel has an enable bit (PWMEx) to start its waveform output. When any of the PWMEx
bits are set (PWMEx = 1), the associated PWM output signal is enabled immediately. However, the actual
PWM waveform is not available on the associated PWM output until its clock source begins its next cycle
due to the synchronization of PWMEx and the clock source. An exception to this is when channels are
concatenated. Refer to Section 15.4.2.7, “PWM 16-Bit Functions,” for more detail.
NOTE
The first PWM cycle after enabling the channel can be irregular.
On the front end of the PWM timer, the clock is enabled to the PWM circuit by the PWMEx bit being high.
There is an edge-synchronizing circuit to guarantee that the clock will only be enabled or disabled at an
edge. When the channel is disabled (PWMEx = 0), the counter for the channel does not count.
15.4.2.2
PWM Polarity
Each channel has a polarity bit to allow starting a waveform cycle with a high or low signal. This is shown
on the block diagram as a mux select of either the Q output or the Q output of the PWM output flip-flop.
When one of the bits in the PWMPOL register is set, the associated PWM channel output is high at the
beginning of the waveform, then goes low when the duty count is reached. Conversely, if the polarity bit
is 0, the output starts low and then goes high when the duty count is reached.
15.4.2.3
PWM Period and Duty
Dedicated period and duty registers exist for each channel and are double buffered so that if they change
while the channel is enabled, the change will NOT take effect until one of the following occurs:
• The effective period ends
• The counter is written (counter resets to 0x0000)
• The channel is disabled
In this way, the output of the PWM will always be either the old waveform or the new waveform, not some
variation in between. If the channel is not enabled, then writes to the period and duty registers will go
directly to the latches as well as the buffer.
A change in duty or period can be forced into effect “immediately” by writing the new value to the duty
and/or period registers and then writing to the counter. This forces the counter to reset and the new duty
and/or period values to be latched. In addition, because the counter is readable it is possible to know where
the count is with respect to the duty value and software can be used to make adjustments.
NOTE
When forcing a new period or duty into effect immediately, an irregular
PWM cycle can occur.
Depending on the polarity bit, the duty registers will contain the count of
either the high time or the low time.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
467
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.4.2.4
PWM Timer Counters
Each channel has a dedicated 8-bit up/down counter which runs at the rate of the selected clock source
(reference Figure 15-34 for the available clock sources and rates). The counter compares to two registers,
a duty register and a period register as shown in Figure 15-35. When the PWM counter matches the duty
register the output flip-flop changes state causing the PWM waveform to also change state. A match
between the PWM counter and the period register behaves differently depending on what output mode is
selected as shown in Figure 15-35 and described in Section 15.4.2.5, “Left Aligned Outputs,” and
Section 15.4.2.6, “Center Aligned Outputs.”
Each channel counter can be read at anytime without affecting the count or the operation of the PWM
channel.
Any value written to the counter causes the counter to reset to 0x0000, the counter direction to be set to
up, the immediate load of both duty and period registers with values from the buffers, and the output to
change according to the polarity bit. When the channel is disabled (PWMEx = 0), the counter stops. When
a channel becomes enabled (PWMEx = 1), the associated PWM counter continues from the count in the
PWMCNTx register. This allows the waveform to resume when the channel is re-enabled. When the
channel is disabled, writing 0 to the period register will cause the counter to reset on the next selected
clock.
NOTE
If the user wants to start a new “clean” PWM waveform without any
“history” from the old waveform, the user must write to channel counter
(PWMCNTx) prior to enabling the PWM channel (PWMEx = 1).
Generally, writes to the counter are done prior to enabling a channel to start from a known state. However,
writing a counter can also be done while the PWM channel is enabled (counting). The effect is similar to
writing the counter when the channel is disabled except that the new period is started immediately with
the output set according to the polarity bit.
NOTE
Writing to the counter while the channel is enabled can cause an irregular
PWM cycle to occur.
The counter is cleared at the end of the effective period (see Section 15.4.2.5, “Left Aligned Outputs,” and
Section 15.4.2.6, “Center Aligned Outputs,” for more details).
Table 15-11. PWM Timer Counter Conditions
Counter Clears (0x0000)
When PWMCNTx register
written to any value
Effective period ends
Counter Counts
When PWM channel is
enabled (PWMEx = 1). Counts
from last value in PWMCNTx.
Counter Stops
When PWM channel is
disabled (PWMEx = 0)
MC9S12HZ256 Data Sheet, Rev. 2.04
468
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
15.4.2.5
Left Aligned Outputs
The PWM timer provides the choice of two types of outputs, left aligned or center aligned outputs. They
are selected with the CAEx bits in the PWMCAE register. If the CAEx bit is cleared (CAEx = 0), the
corresponding PWM output will be left aligned.
In left aligned output mode, the 8-bit counter is configured as an up counter only. It compares to two
registers, a duty register and a period register as shown in the block diagram in Figure 15-35. When the
PWM counter matches the duty register the output flip-flop changes state causing the PWM waveform to
also change state. A match between the PWM counter and the period register resets the counter and the
output flip-flop as shown in Figure 15-35 as well as performing a load from the double buffer period and
duty register to the associated registers as described in Section 15.4.2.3, “PWM Period and Duty.” The
counter counts from 0 to the value in the period register – 1.
NOTE
Changing the PWM output mode from left aligned output to center aligned
output (or vice versa) while channels are operating can cause irregularities
in the PWM output. It is recommended to program the output mode before
enabling the PWM channel.
PPOLx = 0
PPOLx = 1
PWMDTYx
Period = PWMPERx
Figure 15-36. PWM Left Aligned Output Waveform
To calculate the output frequency in left aligned output mode for a particular channel, take the selected
clock source frequency for the channel (A, B, SA, or SB) and divide it by the value in the period register
for that channel.
• PWMx frequency = clock (A, B, SA, or SB) / PWMPERx
• PWMx duty cycle (high time as a% of period):
— Polarity = 0 (PPOLx = 0)
Duty cycle = [(PWMPERx-PWMDTYx)/PWMPERx] * 100%
— Polarity = 1 (PPOLx = 1)
Duty cycle = [PWMDTYx / PWMPERx] * 100%
As an example of a left aligned output, consider the following case:
Clock source = bus clock, where bus clock = 10 MHz (100 ns period)
PPOLx = 0
PWMPERx = 4
PWMDTYx = 1
PWMx frequency = 10 MHz/4 = 2.5 MHz
PWMx period = 400 ns
PWMx duty cycle = 3/4 *100% = 75%
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
469
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Shown below is the output waveform generated.
E = 100 ns
DUTY CYCLE = 75%
PERIOD = 400 ns
Figure 15-37. PWM Left Aligned Output Example Waveform
15.4.2.6
Center Aligned Outputs
For center aligned output mode selection, set the CAEx bit (CAEx = 1) in the PWMCAE register and the
corresponding PWM output will be center aligned.
The 8-bit counter operates as an up/down counter in this mode and is set to up whenever the counter is
equal to 0x0000. The counter compares to two registers, a duty register and a period register as shown in
the block diagram in Figure 15-35. When the PWM counter matches the duty register the output flip-flop
changes state causing the PWM waveform to also change state. A match between the PWM counter and
the period register changes the counter direction from an up-count to a down-count. When the PWM
counter decrements and matches the duty register again, the output flip-flop changes state causing the
PWM output to also change state. When the PWM counter decrements and reaches 0, the counter direction
changes from a down-count back to an up-count and a load from the double buffer period and duty
registers to the associated registers is performed as described in Section 15.4.2.3, “PWM Period and
Duty.” The counter counts from 0 up to the value in the period register and then back down to 0. Thus the
effective period is PWMPERx*2.
NOTE
Changing the PWM output mode from left aligned output to center aligned
output (or vice versa) while channels are operating can cause irregularities
in the PWM output. It is recommended to program the output mode before
enabling the PWM channel.
PPOLx = 0
PPOLx = 1
PWMDTYx
PWMDTYx
PWMPERx
PWMPERx
Period = PWMPERx*2
Figure 15-38. PWM Center Aligned Output Waveform
MC9S12HZ256 Data Sheet, Rev. 2.04
470
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
To calculate the output frequency in center aligned output mode for a particular channel, take the selected
clock source frequency for the channel (A, B, SA, or SB) and divide it by twice the value in the period
register for that channel.
• PWMx frequency = clock (A, B, SA, or SB) / (2*PWMPERx)
• PWMx duty cycle (high time as a% of period):
— Polarity = 0 (PPOLx = 0)
Duty cycle = [(PWMPERx-PWMDTYx)/PWMPERx] * 100%
— Polarity = 1 (PPOLx = 1)
Duty cycle = [PWMDTYx / PWMPERx] * 100%
As an example of a center aligned output, consider the following case:
Clock source = bus clock, where bus clock = 10 MHz (100 ns period)
PPOLx = 0
PWMPERx = 4
PWMDTYx = 1
PWMx frequency = 10 MHz/8 = 1.25 MHz
PWMx period = 800 ns
PWMx duty cycle = 3/4 *100% = 75%
Shown below is the output waveform generated.
E = 100 ns
E = 100 ns
DUTY CYCLE = 75%
PERIOD = 800 ns
Figure 15-39. PWM Center Aligned Output Example Waveform
15.4.2.7
PWM 16-Bit Functions
The PWM timer also has the option of generating 6-channels of 8-bits or 3-channels of 16-bits for greater
PWM resolution}. This 16-bit channel option is achieved through the concatenation of two 8-bit channels.
The PWMCTL register contains three control bits, each of which is used to concatenate a pair of PWM
channels into one 16-bit channel. Channels 4 and 5 are concatenated with the CON45 bit, channels 2 and 3
are concatenated with the CON23 bit, and channels 0 and 1 are concatenated with the CON01 bit.
NOTE
Change these bits only when both corresponding channels are disabled.
When channels 4 and 5 are concatenated, channel 4 registers become the high-order bytes of the double
byte channel as shown in Figure 15-40. Similarly, when channels 2 and 3 are concatenated, channel 2
registers become the high-order bytes of the double byte channel. When channels 0 and 1 are concatenated,
channel 0 registers become the high-order bytes of the double byte channel.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
471
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Clock Source 5
High
Low
PWMCNT4
PWCNT5
Period/Duty Compare
PWM5
Clock Source 3
High
Low
PWMCNT2
PWCNT3
Period/Duty Compare
PWM3
Clock Source 1
High
Low
PWMCNT0
PWCNT1
Period/Duty Compare
PWM1
Figure 15-40. PWM 16-Bit Mode
When using the 16-bit concatenated mode, the clock source is determined by the low-order 8-bit channel
clock select control bits. That is channel 5 when channels 4 and 5 are concatenated, channel 3 when
channels 2 and 3 are concatenated, and channel 1 when channels 0 and 1 are concatenated. The resulting
PWM is output to the pins of the corresponding low-order 8-bit channel as also shown in Figure 15-40.
The polarity of the resulting PWM output is controlled by the PPOLx bit of the corresponding low-order
8-bit channel as well.
After concatenated mode is enabled (CONxx bits set in PWMCTL register), enabling/disabling the
corresponding 16-bit PWM channel is controlled by the low-order PWMEx bit. In this case, the high-order
bytes PWMEx bits have no effect and their corresponding PWM output is disabled.
In concatenated mode, writes to the 16-bit counter by using a 16-bit access or writes to either the low or
high-order byte of the counter will reset the 16-bit counter. Reads of the 16-bit counter must be made by
16-bit access to maintain data coherency.
Either left aligned or center aligned output mode can be used in concatenated mode and is controlled by
the low-order CAEx bit. The high-order CAEx bit has no effect.
MC9S12HZ256 Data Sheet, Rev. 2.04
472
Freescale Semiconductor
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
Table 15-12 is used to summarize which channels are used to set the various control bits when in 16-bit
mode.
Table 15-12. 16-bit Concatenation Mode Summary
15.4.2.8
CONxx
PWMEx
PPOLx
PCLKx
CAEx
PWMx Output
CON45
PWME5
PPOL5
PCLK5
CAE5
PWM5
CON23
PWME3
PPOL3
PCLK3
CAE3
PWM3
CON01
PWME1
PPOL1
PCLK1
CAE1
PWM1
PWM Boundary Cases
Table 15-13 summarizes the boundary conditions for the PWM regardless of the output mode (left aligned
or center aligned) and 8-bit (normal) or 16-bit (concatenation):
Table 15-13. PWM Boundary Cases
1
15.5
PWMDTYx
PWMPERx
PPOLx
PWMx Output
0x0000
(indicates no duty)
>0x0000
1
Always Low
0x0000
(indicates no duty)
>0x0000
0
Always High
XX
0x00001
(indicates no period)
1
Always High
XX
0x00001
(indicates no period)
0
Always Low
>= PWMPERx
XX
1
Always High
>= PWMPERx
XX
0
Always Low
Counter = 0x0000 and does not count.
Resets
The reset state of each individual bit is listed within the register description section (see Section 15.3,
“Memory Map and Register Definition,” which details the registers and their bit-fields. All special
functions or modes which are initialized during or just following reset are described within this section.
• The 8-bit up/down counter is configured as an up counter out of reset.
• All the channels are disabled and all the counters don’t count.
15.6
Interrupts
The PWM8B6C module has only one interrupt which is generated at the time of emergency shutdown, if
the corresponding enable bit (PWMIE) is set. This bit is the enable for the interrupt. The interrupt flag
PWMIF is set whenever the input level of the PWM5 channel changes while PWM5ENA=1 or when
PWMENA is being asserted while the level at PWM5 is active.
A description of the registers involved and affected due to this interrupt is explained in Section 15.3.2.15,
“PWM Shutdown Register (PWMSDN).”
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
473
Chapter 15 Pulse-Width Modulator (PWM8B6CV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
474
Freescale Semiconductor
Chapter 16
Timer Module (TIM16B8CV1)
16.1
Introduction
The basic timer consists of a 16-bit, software-programmable counter driven by a seven-stage
programmable prescaler.
This timer can be used for many purposes, including input waveform measurements while simultaneously
generating an output waveform. Pulse widths can vary from microseconds to many seconds.
This timer contains 8 complete input capture/output compare channels and one pulse accumulator. The
input capture function is used to detect a selected transition edge and record the time. The output compare
function is used for generating output signals or for timer software delays. The 16-bit pulse accumulator
is used to operate as a simple event counter or a gated time accumulator. The pulse accumulator shares
timer channel 7 when in event mode.
A full access for the counter registers or the input capture/output compare registers should take place in
one clock cycle. Accessing high byte and low byte separately for all of these registers may not yield the
same result as accessing them in one word.
16.1.1
Features
The TIM16B8C includes these distinctive features:
• Eight input capture/output compare channels.
• Clock prescaling.
• 16-bit counter.
• 16-bit pulse accumulator.
16.1.2
Modes of Operation
Stop:
Timer is off because clocks are stopped.
Freeze:
Timer counter keep on running, unless TSFRZ in TSCR (0x0006) is set to 1.
Wait:
Counters keep on running, unless TSWAI in TSCR (0x0006) is set to 1.
Normal:
Timer counter keep on running, unless TEN in TSCR (0x0006) is cleared to 0.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
475
Chapter 16 Timer Module (TIM16B8CV1)
16.1.3
Block Diagrams
Bus clock
Prescaler
16-bit Counter
Channel 0
Input capture
Output compare
Channel 1
Input capture
Output compare
Channel 2
Input capture
Output compare
Timer overflow
interrupt
Timer channel 0
interrupt
Channel 3
Input capture
Output compare
Registers
Channel 4
Input capture
Output compare
Channel 5
Input capture
Output compare
Timer channel 7
interrupt
PA overflow
interrupt
PA input
interrupt
Channel 6
Input capture
Output compare
16-bit
Pulse accumulator
Channel 7
Input capture
Output compare
IOC0
IOC1
IOC2
IOC3
IOC4
IOC5
IOC6
IOC7
Figure 16-1. TIM16B8C Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
476
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
TIMCLK (Timer clock)
CLK1
CLK0
Intermodule Bus
Clock select
(PAMOD)
Edge detector
PT7
PACLK
PACLK / 256
PACLK / 65536
Prescaled clock
(PCLK)
4:1 MUX
Interrupt
PACNT
MUX
Divide by 64
M clock
Figure 16-2. 16-Bit Pulse Accumulator Block Diagram
16-bit Main Timer
PTn
Edge detector
Set CnF Interrupt
TCn Input Capture Reg.
Figure 16-3. Interrupt Flag Setting
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
477
Chapter 16 Timer Module (TIM16B8CV1)
PULSE
ACCUMULATOR
PAD
CHANNEL 7 OUTPUT COMPARE
OM7
OL7
OC7M7
Figure 16-4. Channel 7 Output Compare/Pulse Accumulator Logic
NOTE
For more information see the respective functional descriptions in
Section 16.4, “Functional Description,” of this document.
16.2
External Signal Description
The TIM16B8C module has a total of eight external pins.
16.2.1
IOC7 — Input Capture and Output Compare Channel 7 Pin
This pin serves as input capture or output compare for channel 7. This can also be configured as pulse
accumulator input.
16.2.2
IOC6 — Input Capture and Output Compare Channel 6 Pin
This pin serves as input capture or output compare for channel 6.
16.2.3
IOC5 — Input Capture and Output Compare Channel 5 Pin
This pin serves as input capture or output compare for channel 5.
16.2.4
IOC4 — Input Capture and Output Compare Channel 4 Pin
This pin serves as input capture or output compare for channel 4. Pin
16.2.5
IOC3 — Input Capture and Output Compare Channel 3 Pin
This pin serves as input capture or output compare for channel 3.
MC9S12HZ256 Data Sheet, Rev. 2.04
478
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
16.2.6
IOC2 — Input Capture and Output Compare Channel 2 Pin
This pin serves as input capture or output compare for channel 2.
16.2.7
IOC1 — Input Capture and Output Compare Channel 1 Pin
This pin serves as input capture or output compare for channel 1.
16.2.8
IOC0 — Input Capture and Output Compare Channel 0 Pin
This pin serves as input capture or output compare for channel 0.
NOTE
For the description of interrupts see Section 16.6, “Interrupts”.
16.3
Memory Map and Register Definition
This section provides a detailed description of all memory and registers.
16.3.1
Module Memory Map
The memory map for the TIM16B8C module is given below in Table 16-1. The address listed for each
register is the address offset. The total address for each register is the sum of the base address for the
TIM16B8C module and the address offset for each register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
479
Chapter 16 Timer Module (TIM16B8CV1)
Table 16-1. TIM16B8C Memory Map
Address Offset
Use
Access
0x0000
Timer Input Capture/Output Compare Select (TIOS)
R/W
0x0001
Timer Compare Force Register (CFORC)
R/W1
0x0002
Output Compare 7 Mask Register (OC7M)
R/W
0x0003
Output Compare 7 Data Register (OC7D)
R/W
0x0004
Timer Count Register (TCNT(hi))
R/W2
0x0005
Timer Count Register (TCNT(lo))
R/W2
0x0006
Timer System Control Register1 (TSCR1)
R/W
0x0007
Timer Toggle Overflow Register (TTOV)
R/W
0x0008
Timer Control Register1 (TCTL1)
R/W
0x0009
Timer Control Register2 (TCTL2)
R/W
0x000A
Timer Control Register3 (TCTL3)
R/W
0x000B
Timer Control Register4 (TCTL4)
R/W
0x000C
Timer Interrupt Enable Register (TIE)
R/W
0x000D
Timer System Control Register2 (TSCR2)
R/W
0x000E
Main Timer Interrupt Flag1 (TFLG1)
R/W
0x000F
Main Timer Interrupt Flag2 (TFLG2)
R/W
0x0010
Timer Input Capture/Output Compare Register 0 (TC0(hi))
R/W3
0x0011
Timer Input Capture/Output Compare Register 0 (TC0(lo))
R/W3
0x0012
Timer Input Capture/Output Compare Register 1 (TC1(hi))
R/W3
0x0013
Timer Input Capture/Output Compare Register 1 (TC1(lo))
R/W3
0x0014
Timer Input Capture/Output Compare Register 2 (TC2(hi))
R/W3
0x0015
Timer Input Capture/Output Compare Register 2 (TC2(lo))
R/W3
0x0016
Timer Input Capture/Output Compare Register 3 (TC3(hi))
R/W3
0x0017
Timer Input Capture/Output Compare Register 3 (TC3(lo))
R/W3
0x0018
Timer Input Capture/Output Compare Register4 (TC4(hi))
R/W3
0x0019
Timer Input Capture/Output Compare Register 4 (TC4(lo))
R/W3
0x001A
Timer Input Capture/Output Compare Register 5 (TC5(hi))
R/W3
0x001B
Timer Input Capture/Output Compare Register 5 (TC5(lo))
R/W3
0x001C
Timer Input Capture/Output Compare Register 6 (TC6(hi))
R/W3
0x001D
Timer Input Capture/Output Compare Register 6 (TC6(lo))
R/W3
0x001E
Timer Input Capture/Output Compare Register 7 (TC7(hi))
R/W3
0x001F
Timer Input Capture/Output Compare Register 7 (TC7(lo))
R/W3
0x0020
16-Bit Pulse Accumulator Control Register (PACTL)
R/W
0x0021
Pulse Accumulator Flag Register (PAFLG)
R/W
0x0022
Pulse Accumulator Count Register (PACNT(hi))
R/W
0x0023
Pulse Accumulator Count Register (PACNT(lo))
R/W
—4
0x0024 – 0x002C Reserved
0x002D
Timer Test Register (TIMTST)
R/W2
—4
0x002E – 0x002F Reserved
1
Always read 0x0000.
Only writable in special modes (test_mode = 1).
3
Write to these registers have no meaning or effect during input capture.
2
MC9S12HZ256 Data Sheet, Rev. 2.04
480
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
4
Write has no effect; return 0 on read
16.3.2
Register Descriptions
This section consists of register descriptions in address order. Each description includes a standard
register diagram with an associated figure number. Details of register bit and field function follow the
register diagrams, in bit order.
Register
Name
0x0000
TIOS
0x0001
CFORC
0x0002
OC7M
Bit 7
6
5
4
3
2
1
Bit 0
IOS7
IOS6
IOS5
IOS4
IOS3
IOS2
IOS1
IOS0
R
0
0
0
0
0
0
0
0
W
FOC7
FOC6
FOC5
FOC4
FOC3
FOC2
FOC1
FOC0
OC7M7
OC7M6
OC7M5
OC7M4
OC7M3
OC7M2
OC7M1
OC7M0
OC7D7
OC7D6
OC7D5
OC7D4
OC7D3
OC7D2
OC7D1
OC7D0
TCNT15
TCNT14
TCNT13
TCNT12
TCNT11
TCNT10
TCNT9
TCNT8
TCNT7
TCNT6
TCNT5
TCNT4
TCNT3
TCNT2
TCNT1
TCNT0
TEN
TSWAI
TSFRZ
TFFCA
0
0
0
0
TOV7
TOV6
TOV5
TOV4
TOV3
TOV2
TOV1
TOV0
OM7
OL7
OM6
OL6
OM5
OL5
OM4
OL4
OM3
OL3
OM2
OL2
OM1
OL1
OM0
OL0
EDG7B
EDG7A
EDG6B
EDG6A
EDG5B
EDG5A
EDG4B
EDG4A
EDG3B
EDG3A
EDG2B
EDG2A
EDG1B
EDG1A
EDG0B
EDG0A
R
W
R
W
0x0003
OC7D
W
0x0004
TCNTH
W
0x0005
TCNTL
R
R
R
W
0x0006
TSCR2
W
0x0007
TTOV
W
0x0008
TCTL1
0x0009
TCTL2
0x000A
TCTL3
0x000B
TCTL4
R
R
R
W
R
W
R
W
R
W
= Unimplemented or Reserved
Figure 16-5. TIM16B8C Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
481
Chapter 16 Timer Module (TIM16B8CV1)
Register
Name
0x000C
TIE
R
W
0x000D
TSCR2
R
W
0x000E
TFLG1
W
R
0x000F
TFLG2
R
W
R
0x0010–0x001F
TCxH–TCxL
W
R
W
0x0020
PACTL
R
Bit 7
6
5
4
3
2
1
Bit 0
C7I
C6I
C5I
C4I
C3I
C2I
C1I
C0I
0
0
0
TCRE
PR2
PR1
PR0
C6F
C5F
C4F
C3F
C2F
C1F
C0F
0
0
0
0
0
0
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PAEN
PAMOD
PEDGE
CLK1
CLK0
PAOVI
PAI
0
0
0
0
0
0
PAOVF
PAIF
PACNT15
PACNT14
PACNT13
PACNT12
PACNT11
PACNT10
PACNT9
PACNT8
PACNT7
PACNT6
PACNT5
PACNT4
PACNT3
PACNT2
PACNT1
PACNT0
TOI
C7F
TOF
0
W
0x0021
PAFLG
R
W
0x0022
PACNTH
W
R
0x0023
PACNTL
R
W
0x0024–0x002F
Reserved
R
W
= Unimplemented or Reserved
Figure 16-5. TIM16B8C Register Summary (continued)
16.3.2.1
Timer Input Capture/Output Compare Select (TIOS)
7
6
5
4
3
2
1
0
IOS7
IOS6
IOS5
IOS4
IOS3
IOS2
IOS1
IOS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-6. Timer Input Capture/Output Compare Select (TIOS)
MC9S12HZ256 Data Sheet, Rev. 2.04
482
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
Read: Anytime
Write: Anytime
Table 16-2. TIOS Field Descriptions
Field
7:0
IOS[7:0]
16.3.2.2
Description
Input Capture or Output Compare Channel Configuration
0 The corresponding channel acts as an input capture.
1 The corresponding channel acts as an output compare.
Timer Compare Force Register (CFORC)
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
W
FOC7
FOC6
FOC5
FOC4
FOC3
FOC2
FOC1
FOC0
0
0
0
0
0
0
0
0
Reset
Figure 16-7. Timer Compare Force Register (CFORC)
Read: Anytime but will always return 0x0000 (1 state is transient)
Write: Anytime
Table 16-3. CFORC Field Descriptions
Field
Description
7:0
FOC[7:0]
Force Output Compare Action for Channel 7:0 — A write to this register with the corresponding data bit(s) set
causes the action which is programmed for output compare “x” to occur immediately. The action taken is the
same as if a successful comparison had just taken place with the TCx register except the interrupt flag does not
get set.
Note: A successful channel 7 output compare overrides any channel 6:0 compares. If forced output compare on
any channel occurs at the same time as the successful output compare then forced output compare action
will take precedence and interrupt flag won’t get set.
16.3.2.3
Output Compare 7 Mask Register (OC7M)
7
6
5
4
3
2
1
0
OC7M7
OC7M6
OC7M5
OC7M4
OC7M3
OC7M2
OC7M1
OC7M0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-8. Output Compare 7 Mask Register (OC7M)
Read: Anytime
Write: Anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
483
Chapter 16 Timer Module (TIM16B8CV1)
Table 16-4. OC7M Field Descriptions
Field
Description
7:0
OC7M[7:0]
Output Compare 7 Mask — Setting the OC7Mx (x ranges from 0 to 6) will set the corresponding port to be an
output port when the corresponding TIOSx (x ranges from 0 to 6) bit is set to be an output compare.
Note: A successful channel 7 output compare overrides any channel 6:0 compares. For each OC7M bit that is
set, the output compare action reflects the corresponding OC7D bit.
16.3.2.4
Output Compare 7 Data Register (OC7D)
7
6
5
4
3
2
1
0
OC7D7
OC7D6
OC7D5
OC7D4
OC7D3
OC7D2
OC7D1
OC7D0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-9. Output Compare 7 Data Register (OC7D)
Read: Anytime
Write: Anytime
Table 16-5. OC7D Field Descriptions
Field
Description
7:0
OC7D[7:0]
Output Compare 7 Data — A channel 7 output compare can cause bits in the output compare 7 data register
to transfer to the timer port data register depending on the output compare 7 mask register.
16.3.2.5
Timer Count Register (TCNT)
15
14
13
12
11
10
9
9
TCNT15
TCNT14
TCNT13
TCNT12
TCNT11
TCNT10
TCNT9
TCNT8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-10. Timer Count Register High (TCNTH)
7
6
5
4
3
2
1
0
TCNT7
TCNT6
TCNT5
TCNT4
TCNT3
TCNT2
TCNT1
TCNT0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-11. Timer Count Register Low (TCNTL)
The 16-bit main timer is an up counter.
A full access for the counter register should take place in one clock cycle. A separate read/write for high
byte and low byte will give a different result than accessing them as a word.
MC9S12HZ256 Data Sheet, Rev. 2.04
484
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
Read: Anytime
Write: Has no meaning or effect in the normal mode; only writable in special modes (test_mode = 1).
The period of the first count after a write to the TCNT registers may be a different size because the write
is not synchronized with the prescaler clock.
16.3.2.6
Timer System Control Register 1 (TSCR1)
7
6
5
4
TEN
TSWAI
TSFRZ
TFFCA
0
0
0
0
R
3
2
1
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 16-12. Timer System Control Register 1 (TSCR2)
Read: Anytime
Write: Anytime
Table 16-6. TSCR1 Field Descriptions
Field
7
TEN
Description
Timer Enable
0 Disables the main timer, including the counter. Can be used for reducing power consumption.
1 Allows the timer to function normally.
If for any reason the timer is not active, there is no ÷64 clock for the pulse accumulator because the ÷64 is
generated by the timer prescaler.
6
TSWAI
Timer Module Stops While in Wait
0 Allows the timer module to continue running during wait.
1 Disables the timer module when the MCU is in the wait mode. Timer interrupts cannot be used to get the MCU
out of wait.
TSWAI also affects pulse accumulator.
5
TSFRZ
Timer Stops While in Freeze Mode
0 Allows the timer counter to continue running while in freeze mode.
1 Disables the timer counter whenever the MCU is in freeze mode. This is useful for emulation.
TSFRZ does not stop the pulse accumulator.
4
TFFCA
Timer Fast Flag Clear All
0 Allows the timer flag clearing to function normally.
1 For TFLG1(0x000E), a read from an input capture or a write to the output compare channel (0x0010–0x001F)
causes the corresponding channel flag, CnF, to be cleared. For TFLG2 (0x000F), any access to the TCNT
register (0x0004, 0x0005) clears the TOF flag. Any access to the PACNT registers (0x0022, 0x0023) clears
the PAOVF and PAIF flags in the PAFLG register (0x0021). This has the advantage of eliminating software
overhead in a separate clear sequence. Extra care is required to avoid accidental flag clearing due to
unintended accesses.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
485
Chapter 16 Timer Module (TIM16B8CV1)
16.3.2.7
Timer Toggle On Overflow Register 1 (TTOV)
7
6
5
4
3
2
1
0
TOV7
TOV6
TOV5
TOV4
TOV3
TOV2
TOV1
TOV0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-13. Timer Toggle On Overflow Register 1 (TTOV)
Read: Anytime
Write: Anytime
Table 16-7. TTOV Field Descriptions
Field
Description
7:0
TOV[7:0]
Toggle On Overflow Bits — TOVx toggles output compare pin on overflow. This feature only takes effect when
in output compare mode. When set, it takes precedence over forced output compare but not channel 7 override
events.
0 Toggle output compare pin on overflow feature disabled.
1 Toggle output compare pin on overflow feature enabled.
16.3.2.8
Timer Control Register 1/Timer Control Register 2 (TCTL1/TCTL2)
7
6
5
4
3
2
1
0
OM7
OL7
OM6
OL6
OM5
OL5
OM4
OL4
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-14. Timer Control Register 1 (TCTL1)
7
6
5
4
3
2
1
0
OM3
OL3
OM2
OL2
OM1
OL1
OM0
OL0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-15. Timer Control Register 2 (TCTL2)
Read: Anytime
Write: Anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
486
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
Table 16-8. TCTL1/TCTL2 Field Descriptions
Field
Description
7:0
OMx
Output Mode — These eight pairs of control bits are encoded to specify the output action to be taken as a result
of a successful OCx compare. When either OMx or OLx is 1, the pin associated with OCx becomes an output
tied to OCx.
Note: To enable output action by OMx bits on timer port, the corresponding bit in OC7M should be cleared.
7:0
OLx
Output Level — These eight pairs of control bits are encoded to specify the output action to be taken as a result
of a successful OCx compare. When either OMx or OLx is 1, the pin associated with OCx becomes an output
tied to OCx.
Note: To enable output action by OLx bits on timer port, the corresponding bit in OC7M should be cleared.
Table 16-9. Compare Result Output Action
OMx
OLx
Action
0
0
Timer disconnected from output pin logic
0
1
Toggle OCx output line
1
0
Clear OCx output line to zero
1
1
Set OCx output line to one
To operate the 16-bit pulse accumulator independently of input capture or output compare 7 and 0
respectively the user must set the corresponding bits IOSx = 1, OMx = 0 and OLx = 0. OC7M7 in the
OC7M register must also be cleared.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
487
Chapter 16 Timer Module (TIM16B8CV1)
16.3.2.9
Timer Control Register 3/Timer Control Register 4 (TCTL3 and TCTL4)
7
6
5
4
3
2
1
0
EDG7B
EDG7A
EDG6B
EDG6A
EDG5B
EDG5A
EDG4B
EDG4A
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-16. Timer Control Register 3 (TCTL3)
7
6
5
4
3
2
1
0
EDG3B
EDG3A
EDG2B
EDG2A
EDG1B
EDG1A
EDG0B
EDG0A
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-17. Timer Control Register 4 (TCTL4)
Read: Anytime
Write: Anytime.
Table 16-10. TCTL3/TCTL4 Field Descriptions
Field
7:0
EDGnB
EDGnA
Description
Input Capture Edge Control — These eight pairs of control bits configure the input capture edge detector
circuits.
Table 16-11. Edge Detector Circuit Configuration
EDGnB
EDGnA
Configuration
0
0
Capture disabled
0
1
Capture on rising edges only
1
0
Capture on falling edges only
1
1
Capture on any edge (rising or falling)
MC9S12HZ256 Data Sheet, Rev. 2.04
488
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
16.3.2.10 Timer Interrupt Enable Register (TIE)
7
6
5
4
3
2
1
0
C7I
C6I
C5I
C4I
C3I
C2I
C1I
C0I
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-18. Timer Interrupt Enable Register (TIE)
Read: Anytime
Write: Anytime.
Table 16-12. TIE Field Descriptions
Field
Description
7:0
C7I:C0I
Input Capture/Output Compare “x” Interrupt Enable — The bits in TIE correspond bit-for-bit with the bits in
the TFLG1 status register. If cleared, the corresponding flag is disabled from causing a hardware interrupt. If set,
the corresponding flag is enabled to cause a interrupt.
16.3.2.11 Timer System Control Register 2 (TSCR2)
7
R
6
5
4
0
0
0
TOI
3
2
1
0
TCRE
PR2
PR1
PR0
0
0
0
0
W
Reset
0
0
0
0
= Unimplemented or Reserved
Figure 16-19. Timer System Control Register 2 (TSCR2)
Read: Anytime
Write: Anytime.
Table 16-13. TSCR2 Field Descriptions
Field
7
TOI
Description
Timer Overflow Interrupt Enable
0 Interrupt inhibited.
1 Hardware interrupt requested when TOF flag set.
3
TCRE
Timer Counter Reset Enable — This bit allows the timer counter to be reset by a successful output compare 7
event. This mode of operation is similar to an up-counting modulus counter.
0 Counter reset inhibited and counter free runs.
1 Counter reset by a successful output compare 7.
If TC7 = 0x0000 and TCRE = 1, TCNT will stay at 0x0000 continuously. If TC7 = 0xFFFF and TCRE = 1, TOF
will never be set when TCNT is reset from 0xFFFF to 0x0000.
2
PR[2:0]
Timer Prescaler Select — These three bits select the frequency of the timer prescaler clock derived from the
Bus Clock as shown in Table 16-14.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
489
Chapter 16 Timer Module (TIM16B8CV1)
Table 16-14. Timer Clock Selection
PR2
PR1
PR0
Timer Clock
0
0
0
Bus Clock / 1
0
0
1
Bus Clock / 2
0
1
0
Bus Clock / 4
0
1
1
Bus Clock / 8
1
0
0
Bus Clock / 16
1
0
1
Bus Clock / 32
1
1
0
Bus Clock / 64
1
1
1
Bus Clock / 128
NOTE
The newly selected prescale factor will not take effect until the next
synchronized edge where all prescale counter stages equal zero.
16.3.2.12 Main Timer Interrupt Flag 1 (TFLG1)
7
6
5
4
3
2
1
0
C7F
C6F
C5F
C4F
C3F
C2F
C1F
C0F
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-20. Main Timer Interrupt Flag 1 (TFLG1)
Read: Anytime
Write: Used in the clearing mechanism (set bits cause corresponding bits to be cleared). Writing a zero
will not affect current status of the bit.
Table 16-15. TRLG1 Field Descriptions
Field
7:0
C[7:0]F
Description
Input Capture/Output Compare Channel “x” Flag — These flags are set when an input capture or output
compare event occurs. Clear a channel flag by writing one to it.
When TFFCA bit in TSCR register is set, a read from an input capture or a write into an output compare channel
(0x0010–0x001F) will cause the corresponding channel flag CxF to be cleared.
MC9S12HZ256 Data Sheet, Rev. 2.04
490
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
16.3.2.13 Main Timer Interrupt Flag 2 (TFLG2)
7
R
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TOF
W
Reset
0
Unimplemented or Reserved
Figure 16-21. Main Timer Interrupt Flag 2 (TFLG2)
TFLG2 indicates when interrupt conditions have occurred. To clear a bit in the flag register, write the bit
to one.
Read: Anytime
Write: Used in clearing mechanism (set bits cause corresponding bits to be cleared).
Any access to TCNT will clear TFLG2 register if the TFFCA bit in TSCR register is set.
Table 16-16. TRLG2 Field Descriptions
Field
Description
7
TOF
Timer Overflow Flag — Set when 16-bit free-running timer overflows from 0xFFFF to 0x0000. This bit is cleared
automatically by a write to the TFLG2 register with bit 7 set. (See also TCRE control bit explanation.)
16.3.2.14 Timer Input Capture/Output Compare Registers High and Low 0–7
(TCxH and TCxL)
15
14
13
12
11
10
9
0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-22. Timer Input Capture/Output Compare Register x High (TCxH)
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-23. Timer Input Capture/Output Compare Register x Low (TCxL)
Depending on the TIOS bit for the corresponding channel, these registers are used to latch the value of the
free-running counter when a defined transition is sensed by the corresponding input capture edge detector
or to trigger an output action for output compare.
Read: Anytime
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
491
Chapter 16 Timer Module (TIM16B8CV1)
Write: Anytime for output compare function.Writes to these registers have no meaning or effect during
input capture. All timer input capture/output compare registers are reset to 0x0000.
NOTE
Read/Write access in byte mode for high byte should takes place before low
byte otherwise it will give a different result.
16.3.2.15 16-Bit Pulse Accumulator Control Register (PACTL)
7
R
6
5
4
3
2
1
0
PAEN
PAMOD
PEDGE
CLK1
CLK0
PAOVI
PAI
0
0
0
0
0
0
0
0
W
Reset
0
Unimplemented or Reserved
Figure 16-24. 16-Bit Pulse Accumulator Control Register (PACTL)
When PAEN is set, the PACT is enabled.The PACT shares the input pin with IOC7.
Read: Any time
Write: Any time
Table 16-17. PACTL Field Descriptions
Field
6
PAEN
Description
Pulse Accumulator System Enable — PAEN is independent from TEN. With timer disabled, the pulse
accumulator can function unless pulse accumulator is disabled.
0 16-Bit Pulse Accumulator system disabled.
1 Pulse Accumulator system enabled.
5
PAMOD
Pulse Accumulator Mode — This bit is active only when the Pulse Accumulator is enabled (PAEN = 1). See
Table 16-18.
0 Event counter mode.
1 Gated time accumulation mode.
4
PEDGE
Pulse Accumulator Edge Control — This bit is active only when the Pulse Accumulator is enabled (PAEN = 1).
For PAMOD bit = 0 (event counter mode). See Table 16-18.
0 Falling edges on IOC7 pin cause the count to be incremented.
1 Rising edges on IOC7 pin cause the count to be incremented.
For PAMOD bit = 1 (gated time accumulation mode).
0 IOC7 input pin high enables M (bus clock) divided by 64 clock to Pulse Accumulator and the trailing falling
edge on IOC7 sets the PAIF flag.
1 IOC7 input pin low enables M (bus clock) divided by 64 clock to Pulse Accumulator and the trailing rising edge
on IOC7 sets the PAIF flag.
3:2
CLK[1:0]
Clock Select Bits — Refer to Table 16-19.
MC9S12HZ256 Data Sheet, Rev. 2.04
492
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
Table 16-17. PACTL Field Descriptions (continued)
Field
1
PAOVI
0
PAI
Description
Pulse Accumulator Overflow Interrupt Enable
0 Interrupt inhibited.
1 Interrupt requested if PAOVF is set.
Pulse Accumulator Input Interrupt Enable
0 Interrupt inhibited.
1 Interrupt requested if PAIF is set.
Table 16-18. Pin Action
PAMOD
PEDGE
Pin Action
0
0
Falling edge
0
1
Rising edge
1
0
Div. by 64 clock enabled with pin high level
1
1
Div. by 64 clock enabled with pin low level
NOTE
If the timer is not active (TEN = 0 in TSCR), there is no divide-by-64
because the ÷64 clock is generated by the timer prescaler.
Table 16-19. Timer Clock Selection
CLK1
CLK0
Timer Clock
0
0
Use timer prescaler clock as timer counter clock
0
1
Use PACLK as input to timer counter clock
1
0
Use PACLK/256 as timer counter clock frequency
1
1
Use PACLK/65536 as timer counter clock frequency
For the description of PACLK please refer Figure 16-24.
If the pulse accumulator is disabled (PAEN = 0), the prescaler clock from the timer is always used as an
input clock to the timer counter. The change from one selected clock to the other happens immediately
after these bits are written.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
493
Chapter 16 Timer Module (TIM16B8CV1)
16.3.2.16 Pulse Accumulator Flag Register (PAFLG)
R
7
6
5
4
3
2
0
0
0
0
0
0
1
0
PAOVF
PAIF
0
0
W
Reset
0
0
0
0
0
0
Unimplemented or Reserved
Figure 16-25. Pulse Accumulator Flag Register (PAFLG)
Read: Anytime
Write: Anytime
When the TFFCA bit in the TSCR register is set, any access to the PACNT register will clear all the flags
in the PAFLG register.
Table 16-20. PAFLG Field Descriptions
Field
Description
1
PAOVF
Pulse Accumulator Overflow Flag — Set when the 16-bit pulse accumulator overflows from 0xFFFF to 0x0000.
This bit is cleared automatically by a write to the PAFLG register with bit 1 set.
0
PAIF
Pulse Accumulator Input edge Flag — Set when the selected edge is detected at the IOC7 input pin.In event
mode the event edge triggers PAIF and in gated time accumulation mode the trailing edge of the gate signal at
the IOC7 input pin triggers PAIF.
This bit is cleared by a write to the PAFLG register with bit 0 set.
Any access to the PACNT register will clear all the flags in this register when TFFCA bit in register TSCR(0x0006)
is set.
MC9S12HZ256 Data Sheet, Rev. 2.04
494
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
16.3.2.17 Pulse Accumulators Count Registers (PACNT)
15
14
13
12
11
10
9
0
PACNT15
PACNT14
PACNT13
PACNT12
PACNT11
PACNT10
PACNT9
PACNT8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-26. Pulse Accumulator Count Register High (PACNTH)
7
6
5
4
3
2
1
0
PACNT7
PACNT6
PACNT5
PACNT4
PACNT3
PACNT2
PACNT1
PACNT0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 16-27. Pulse Accumulator Count Register Low (PACNTL)
Read: Anytime
Write: Anytime
These registers contain the number of active input edges on its input pin since the last reset.
When PACNT overflows from 0xFFFF to 0x0000, the Interrupt flag PAOVF in PAFLG (0x0021) is set.
Full count register access should take place in one clock cycle. A separate read/write for high byte and low
byte will give a different result than accessing them as a word.
NOTE
Reading the pulse accumulator counter registers immediately after an active
edge on the pulse accumulator input pin may miss the last count because the
input has to be synchronized with the bus clock first.
16.4
Functional Description
This section provides a complete functional description of the timer TIM16B8C block. Please refer to the
detailed timer block diagram in Figure 16-28 as necessary.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
495
Chapter 16 Timer Module (TIM16B8CV1)
Bus Clock
CLK[1:0]
PR[2:1:0]
channel 7 output
compare
PACLK
PACLK/256
PACLK/65536
MUX
TCRE
PRESCALER
CxI
TCNT(hi):TCNT(lo)
CxF
CLEAR COUNTER
16-BIT COUNTER
TOF
INTERRUPT
LOGIC
TOI
TE
TOF
CHANNEL 0
16-BIT COMPARATOR
OM:OL0
TC0
EDG0A
C0F
C0F
EDGE
DETECT
EDG0B
CH. 0 CAPTURE
IOC0 PIN
LOGIC CH. 0COMPARE
TOV0
IOC0 PIN
IOC0
CHANNEL 1
16-BIT COMPARATOR
OM:OL1
EDGE
DETECT
EDG1B
EDG1A
C1F
C1F
TC1
CH. 1 CAPTURE
IOC1 PIN
LOGIC CH. 1 COMPARE
TOV1
IOC1 PIN
IOC1
CHANNEL2
CHANNEL7
16-BIT COMPARATOR
TC7
OM:O73
EDG7A
EDGE
DETECT
EDG7B
PAOVF
C7F
C7F
PACNT(hi):PACNT(lo)
TOV7
IOC7
PEDGE
PAE
PACLK/65536
CH.7 CAPTURE
IOC7 PIN PA INPUT
LOGIC CH. 7 COMPARE IOC7 PIN
EDGE
DETECT
16-BIT COUNTER
PACLK
PACLK/256
PAMOD
INTERRUPT
REQUEST
INTERRUPT
LOGIC
PAIF
DIVIDE-BY-64
PAOVI
PAI
PAOVF
PAIF
Bus Clock
PAOVF
PAOVI
Figure 16-28. Detailed Timer Block Diagram
16.4.1
Prescaler
The prescaler divides the bus clock by 1,2,4,8,16,32,64 or 128. The prescaler select bits, PR[2:0], select
the prescaler divisor. PR[2:0] are in timer system control register 2 (TSCR2).
MC9S12HZ256 Data Sheet, Rev. 2.04
496
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
16.4.2
Input Capture
Clearing the I/O (input/output) select bit, IOSx, configures channel x as an input capture channel. The
input capture function captures the time at which an external event occurs. When an active edge occurs on
the pin of an input capture channel, the timer transfers the value in the timer counter into the timer channel
registers, TCx.
The minimum pulse width for the input capture input is greater than two bus clocks.
An input capture on channel x sets the CxF flag. The CxI bit enables the CxF flag to generate interrupt
requests.
16.4.3
Output Compare
Setting the I/O select bit, IOSx, configures channel x as an output compare channel. The output compare
function can generate a periodic pulse with a programmable polarity, duration, and frequency. When the
timer counter reaches the value in the channel registers of an output compare channel, the timer can set,
clear, or toggle the channel pin. An output compare on channel x sets the CxF flag. The CxI bit enables the
CxF flag to generate interrupt requests.
The output mode and level bits, OMx and OLx, select set, clear, toggle on output compare. Clearing both
OMx and OLx disconnects the pin from the output logic.
Setting a force output compare bit, FOCx, causes an output compare on channel x. A forced output
compare does not set the channel flag.
A successful output compare on channel 7 overrides output compares on all other output compare
channels. The output compare 7 mask register masks the bits in the output compare 7 data register. The
timer counter reset enable bit, TCRE, enables channel 7 output compares to reset the timer counter. A
channel 7 output compare can reset the timer counter even if the IOC7 pin is being used as the pulse
accumulator input.
Writing to the timer port bit of an output compare pin does not affect the pin state. The value written is
stored in an internal latch. When the pin becomes available for general-purpose output, the last value
written to the bit appears at the pin.
16.4.4
Pulse Accumulator
The pulse accumulator (PACNT) is a 16-bit counter that can operate in two modes:
Event counter mode — Counting edges of selected polarity on the pulse accumulator input pin, PAI.
Gated time accumulation mode — Counting pulses from a divide-by-64 clock. The PAMOD bit selects the
mode of operation.
The minimum pulse width for the PAI input is greater than two bus clocks.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
497
Chapter 16 Timer Module (TIM16B8CV1)
16.4.5
Event Counter Mode
Clearing the PAMOD bit configures the PACNT for event counter operation. An active edge on the IOC7
pin increments the pulse accumulator counter. The PEDGE bit selects falling edges or rising edges to
increment the count.
NOTE
The PACNT input and timer channel 7 use the same pin IOC7. To use the
IOC7, disconnect it from the output logic by clearing the channel 7 output
mode and output level bits, OM7 and OL7. Also clear the channel 7 output
compare 7 mask bit, OC7M7.
The Pulse Accumulator counter register reflect the number of active input edges on the PACNT input pin
since the last reset.
The PAOVF bit is set when the accumulator rolls over from 0xFFFF to 0x0000. The pulse accumulator
overflow interrupt enable bit, PAOVI, enables the PAOVF flag to generate interrupt requests.
NOTE
The pulse accumulator counter can operate in event counter mode even
when the timer enable bit, TEN, is clear.
16.4.6
Gated Time Accumulation Mode
Setting the PAMOD bit configures the pulse accumulator for gated time accumulation operation. An active
level on the PACNT input pin enables a divided-by-64 clock to drive the pulse accumulator. The PEDGE
bit selects low levels or high levels to enable the divided-by-64 clock.
The trailing edge of the active level at the IOC7 pin sets the PAIF. The PAI bit enables the PAIF flag to
generate interrupt requests.
The pulse accumulator counter register reflect the number of pulses from the divided-by-64 clock since the
last reset.
NOTE
The timer prescaler generates the divided-by-64 clock. If the timer is not
active, there is no divided-by-64 clock.
16.5
Resets
The reset state of each individual bit is listed within Section 16.3, “Memory Map and Register Definition”
which details the registers and their bit fields.
16.6
Interrupts
This section describes interrupts originated by the TIM16B8C block. Table 16-21 lists the interrupts
generated by the TIM16B8C to communicate with the MCU.
MC9S12HZ256 Data Sheet, Rev. 2.04
498
Freescale Semiconductor
Chapter 16 Timer Module (TIM16B8CV1)
Table 16-21. TIM16B8CV1 Interrupts
1
Interrupt
Offset1
Vector1
Priority1
Source
Description
C[7:0]F
—
—
—
Timer Channel 7–0
Active high timer channel interrupts 7–0
PAOVI
—
—
—
Pulse Accumulator
Input
Active high pulse accumulator input interrupt
PAOVF
—
—
—
Pulse Accumulator
Overflow
Pulse accumulator overflow interrupt
TOF
—
—
—
Timer Overflow
Timer Overflow interrupt
Chip Dependent.
The TIM16B8C uses a total of 11 interrupt vectors. The interrupt vector offsets and interrupt numbers are
chip dependent.
16.6.1
Channel [7:0] Interrupt (C[7:0]F)
This active high outputs will be asserted by the module to request a timer channel 7 – 0 interrupt to be
serviced by the system controller.
16.6.2
Pulse Accumulator Input Interrupt (PAOVI)
This active high output will be asserted by the module to request a timer pulse accumulator input interrupt
to be serviced by the system controller.
16.6.3
Pulse Accumulator Overflow Interrupt (PAOVF)
This active high output will be asserted by the module to request a timer pulse accumulator overflow
interrupt to be serviced by the system controller.
16.6.4
Timer Overflow Interrupt (TOF)
This active high output will be asserted by the module to request a timer overflow interrupt to be serviced
by the system controller.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
499
Chapter 16 Timer Module (TIM16B8CV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
500
Freescale Semiconductor
Chapter 17
Dual Output Voltage Regulator (VREG3V3V2)
17.1
Introduction
The VREG3V3 is a dual output voltage regulator providing two separate 2.5 V (typical) supplies differing
in the amount of current that can be sourced. The regulator input voltage range is from 3.3 V up to 5 V
(typical).
17.1.1
Features
The block VREG3V3 includes these distinctive features:
• Two parallel, linear voltage regulators
— Bandgap reference
• Low-voltage detect (LVD) with low-voltage interrupt (LVI)
• Power-on reset (POR)
• Low-voltage reset (LVR)
17.1.2
Modes of Operation
There are three modes VREG3V3 can operate in:
• Full-performance mode (FPM) (MCU is not in stop mode)
The regulator is active, providing the nominal supply voltage of 2.5 V with full current sourcing
capability at both outputs. Features LVD (low-voltage detect), LVR (low-voltage reset), and POR
(power-on reset) are available.
• Reduced-power mode (RPM) (MCU is in stop mode)
The purpose is to reduce power consumption of the device. The output voltage may degrade to a
lower value than in full-performance mode, additionally the current sourcing capability is
substantially reduced. Only the POR is available in this mode, LVD and LVR are disabled.
• Shutdown mode
Controlled by VREGEN (see device overview chapter for connectivity of VREGEN).
This mode is characterized by minimum power consumption. The regulator outputs are in a high
impedance state, only the POR feature is available, LVD and LVR are disabled.
This mode must be used to disable the chip internal regulator VREG3V3, i.e., to bypass the
VREG3V3 to use external supplies.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
501
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
17.1.3
Block Diagram
Figure 17-1 shows the function principle of VREG3V3 by means of a block diagram. The regulator core
REG consists of two parallel sub-blocks, REG1 and REG2, providing two independent output voltages.
VDDPLL
REG2
VDDR
REG
VSSPLL
VDDA
VDD
REG1
LVD
LVR
LVR
POR
POR
VSS
VSSA
VREGEN
CTRL
LVI
REG: Regulator Core
LVD: Low Voltage Detect
CTRL: Regulator Control
LVR: Low Voltage Reset
POR: Power-on Reset
PIN
Figure 17-1. VREG3V3 Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
502
Freescale Semiconductor
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
17.2
External Signal Description
Due to the nature of VREG3V3 being a voltage regulator providing the chip internal power supply
voltages most signals are power supply signals connected to pads.
Table 17-1 shows all signals of VREG3V3 associated with pins.
Table 17-1. VREG3V3 — Signal Properties
Name
Port
VDDR
—
VDDA
Function
Reset State
Pull Up
VREG3V3 power input (positive supply)
—
—
—
VREG3V3 quiet input (positive supply)
—
—
VSSA
—
VREG3V3 quiet input (ground)
—
—
VDD
—
VREG3V3 primary output (positive supply)
—
—
VSS
—
VREG3V3 primary output (ground)
—
—
VDDPLL
—
VREG3V3 secondary output (positive supply)
—
—
VSSPLL
—
VREG3V3 secondary output (ground)
—
—
VREGEN (optional)
—
VREG3V3 (Optional) Regulator Enable
—
—
NOTE
Check device overview chapter for connectivity of the signals.
17.2.1
VDDR — Regulator Power Input
Signal VDDR is the power input of VREG3V3. All currents sourced into the regulator loads flow through
this pin. A chip external decoupling capacitor (100 nF...220 nF, X7R ceramic) between VDDR and VSSR
can smoothen ripple on VDDR.
For entering Shutdown Mode, pin VDDR should also be tied to ground on devices without a VREGEN pin.
17.2.2
VDDA, VSSA — Regulator Reference Supply
Signals VDDA/VSSA which are supposed to be relatively quiet are used to supply the analog parts of the
regulator. Internal precision reference circuits are supplied from these signals. A chip external decoupling
capacitor (100 nF...220 nF, X7R ceramic) between VDDA and VSSA can further improve the quality of this
supply.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
503
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
17.2.3
VDD, VSS — Regulator Output1 (Core Logic)
Signals VDD/VSS are the primary outputs of VREG3V3 that provide the power supply for the core logic.
These signals are connected to device pins to allow external decoupling capacitors (100 nF...220 nF, X7R
ceramic).
In Shutdown Mode an external supply at VDD/VSS can replace the voltage regulator.
17.2.4
VDDPLL, VSSPLL — Regulator Output2 (PLL)
Signals VDDPLL/VSSPLL are the secondary outputs of VREG3V3 that provide the power supply for the
PLL and oscillator. These signals are connected to device pins to allow external decoupling capacitors
(100 nF...220 nF, X7R ceramic).
In Shutdown Mode an external supply at VDDPLL/VSSPLL can replace the voltage regulator.
17.2.5
VREGEN — Optional Regulator Enable
This optional signal is used to shutdown VREG3V3. In that case VDD/VSS and VDDPLL/VSSPLL must be
provided externally. Shutdown Mode is entered with VREGEN being low. If VREGEN is high, the
VREG3V3 is either in Full Performance Mode or in Reduced Power Mode.
For the connectivity of VREGEN see device overview chapter.
NOTE
Switching from FPM or RPM to shutdown of VREG3V3 and vice versa is
not supported while the MCU is powered.
17.3
Memory Map and Register Definition
This subsection provides a detailed description of all registers accessible in VREG3V3.
17.3.1
Module Memory Map
Figure 17-2 provides an overview of all used registers.
Table 17-2. VREG3V3 Memory Map
Address
Offset
Use
Access
0x0000
VREG3V3 Control Register (VREGCTRL)
R/W
MC9S12HZ256 Data Sheet, Rev. 2.04
504
Freescale Semiconductor
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
17.3.2
Register Descriptions
The following paragraphs describe, in address order, all the VREG3V3 registers and their individual bits.
17.3.2.1
VREG3V3 — Control Register (VREGCTRL)
The VREGCTRL register allows to separately enable features of VREG3V3.
R
7
6
5
4
3
2
0
0
0
0
0
LVDS
1
0
LVIE
LVIF
0
0
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 17-2. VREG3V3 — Control Register (VREGCTRL)
Table 17-3. MCCTL1 Field Descriptions
Field
Description
2
LVDS
Low-Voltage Detect Status Bit — This read-only status bit reflects the input voltage. Writes have no effect.
0 Input voltage VDDA is above level VLVID or RPM or shutdown mode.
1 Input voltage VDDA is below level VLVIA and FPM.
1
LVIE
Low-Voltage Interrupt Enable Bit
0 Interrupt request is disabled.
1 Interrupt will be requested whenever LVIF is set.
0
LVIF
Low-Voltage Interrupt Flag — LVIF is set to 1 when LVDS status bit changes. This flag can only be cleared by
writing a 1. Writing a 0 has no effect. If enabled (LVIE = 1), LVIF causes an interrupt request.
0 No change in LVDS bit.
1 LVDS bit has changed.
NOTE
On entering the Reduced Power Mode the LVIF is not cleared by the
VREG3V3.
17.4
Functional Description
Block VREG3V3 is a voltage regulator as depicted in Figure 17-1. The regulator functional elements are
the regulator core (REG), a low-voltage detect module (LVD), a power-on reset module (POR) and a
low-voltage reset module (LVR). There is also the regulator control block (CTRL) which represents the
interface to the digital core logic but also manages the operating modes of VREG3V3.
17.4.1
REG — Regulator Core
VREG3V3, respectively its regulator core has two parallel, independent regulation loops (REG1 and
REG2) that differ only in the amount of current that can be sourced to the connected loads. Therefore, only
REG1 providing the supply at VDD/VSS is explained. The principle is also valid for REG2.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
505
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
The regulator is a linear series regulator with a bandgap reference in its Full Performance Mode and a
voltage clamp in Reduced Power Mode. All load currents flow from input VDDR to VSS or VSSPLL, the
reference circuits are connected to VDDA and VSSA.
17.4.2
Full-Performance Mode
In Full Performance Mode, a fraction of the output voltage (VDD) and the bandgap reference voltage are
fed to an operational amplifier. The amplified input voltage difference controls the gate of an output driver
which basically is a large NMOS transistor connected to the output.
17.4.3
Reduced-Power Mode
In Reduced Power Mode, the driver gate is connected to a buffered fraction of the input voltage (VDDR).
The operational amplifier and the bandgap are disabled to reduce power consumption.
17.4.4
LVD — Low-Voltage Detect
sub-block LVD is responsible for generating the low-voltage interrupt (LVI). LVD monitors the input
voltage (VDDA–VSSA) and continuously updates the status flag LVDS. Interrupt flag LVIF is set whenever
status flag LVDS changes its value. The LVD is available in FPM and is inactive in Reduced Power Mode
and Shutdown Mode.
17.4.5
POR — Power-On Reset
This functional block monitors output VDD. If VDD is below VPORD, signal POR is high, if it exceeds
VPORD, the signal goes low. The transition to low forces the CPU in the power-on sequence.
Due to its role during chip power-up this module must be active in all operating modes of VREG3V3.
17.4.6
LVR — Low-Voltage Reset
Block LVR monitors the primary output voltage VDD. If it drops below the assertion level (VLVRA) signal
LVR asserts and when rising above the deassertion level (VLVRD) signal LVR negates again. The LVR
function is available only in Full Performance Mode.
17.4.7
CTRL — Regulator Control
This part contains the register block of VREG3V3 and further digital functionality needed to control the
operating modes. CTRL also represents the interface to the digital core logic.
MC9S12HZ256 Data Sheet, Rev. 2.04
506
Freescale Semiconductor
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
17.5
Resets
This subsection describes how VREG3V3 controls the reset of the MCU.The reset values of registers and
signals are provided in Section 17.3, “Memory Map and Register Definition”. Possible reset sources are
listed in Table 17-4.
Table 17-4. VREG3V3 — Reset Sources
Reset Source
17.5.1
Local Enable
Power-on reset
Always active
Low-voltage reset
Available only in Full Performance Mode
Power-On Reset
During chip power-up the digital core may not work if its supply voltage VDD is below the POR
deassertion level (VPORD). Therefore, signal POR which forces the other blocks of the device into reset is
kept high until VDD exceeds VPORD. Then POR becomes low and the reset generator of the device
continues the start-up sequence. The power-on reset is active in all operation modes of VREG3V3.
17.5.2
Low-Voltage Reset
For details on low-voltage reset see Section 17.4.6, “LVR — Low-Voltage Reset”.
17.6
Interrupts
This subsection describes all interrupts originated by VREG3V3.
The interrupt vectors requested by VREG3V3 are listed in Table 17-5. Vector addresses and interrupt
priorities are defined at MCU level.
Table 17-5. VREG3V3 — Interrupt Vectors
Interrupt Source
Low Voltage Interrupt (LVI)
17.6.1
Local Enable
LVIE = 1; Available only in Full Performance Mode
LVI — Low-Voltage Interrupt
In FPM VREG3V3 monitors the input voltage VDDA. Whenever VDDA drops below level VLVIA the status
bit LVDS is set to 1. Vice versa, LVDS is reset to 0 when VDDA rises above level VLVID. An interrupt,
indicated by flag LVIF = 1, is triggered by any change of the status bit LVDS if interrupt enable bit
LVIE = 1.
NOTE
On entering the Reduced Power Mode, the LVIF is not cleared by the
VREG3V3.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
507
Chapter 17 Dual Output Voltage Regulator (VREG3V3V2)
MC9S12HZ256 Data Sheet, Rev. 2.04
508
Freescale Semiconductor
Chapter 18
Background Debug Module (BDMV4)
18.1
Introduction
This section describes the functionality of the background debug module (BDM) sub-block of the HCS12
core platform.
A block diagram of the BDM is shown in Figure 18-1.
HOST
SYSTEM
BKGD
16-BIT SHIFT REGISTER
ADDRESS
ENTAG
BDMACT
INSTRUCTION DECODE
AND EXECUTION
TRACE
SDV
ENBDM
BUS INTERFACE
AND
CONTROL LOGIC
DATA
CLOCKS
STANDARD BDM
FIRMWARE
LOOKUP TABLE
CLKSW
Figure 18-1. BDM Block Diagram
The background debug module (BDM) sub-block is a single-wire, background debug system implemented
in on-chip hardware for minimal CPU intervention. All interfacing with the BDM is done via the BKGD
pin.
BDMV4 has enhanced capability for maintaining synchronization between the target and host while
allowing more flexibility in clock rates. This includes a sync signal to show the clock rate and a handshake
signal to indicate when an operation is complete. The system is backwards compatible with older external
interfaces.
18.1.1
•
•
•
•
•
•
Features
Single-wire communication with host development system
BDMV4 (and BDM2): Enhanced capability for allowing more flexibility in clock rates
BDMV4: SYNC command to determine communication rate
BDMV4: GO_UNTIL command
BDMV4: Hardware handshake protocol to increase the performance of the serial communication
Active out of reset in special single-chip mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
509
Chapter 18 Background Debug Module (BDMV4)
•
•
•
•
•
•
•
Nine hardware commands using free cycles, if available, for minimal CPU intervention
Hardware commands not requiring active BDM
15 firmware commands execute from the standard BDM firmware lookup table
Instruction tagging capability
Software control of BDM operation during wait mode
Software selectable clocks
When secured, hardware commands are allowed to access the register space in special single-chip
mode, if the FLASH and EEPROM erase tests fail.
18.1.2
Modes of Operation
BDM is available in all operating modes but must be enabled before firmware commands are executed.
Some system peripherals may have a control bit which allows suspending the peripheral function during
background debug mode.
18.1.2.1
Regular Run Modes
All of these operations refer to the part in run mode. The BDM does not provide controls to conserve power
during run mode.
• Normal operation
General operation of the BDM is available and operates the same in all normal modes.
• Special single-chip mode
In special single-chip mode, background operation is enabled and active out of reset. This allows
programming a system with blank memory.
• Special peripheral mode
BDM is enabled and active immediately out of reset. BDM can be disabled
by clearing the BDMACT bit in the BDM status (BDMSTS) register. The
BDM serial system should not be used in special peripheral mode.
•
Emulation modes
General operation of the BDM is available and operates the same as in normal modes.
18.1.2.2
Secure Mode Operation
If the part is in secure mode, the operation of the BDM is reduced to a small subset of its regular run mode
operation. Secure operation prevents access to FLASH or EEPROM other than allowing erasure.
18.2
External Signal Description
A single-wire interface pin is used to communicate with the BDM system. Two additional pins are used
for instruction tagging. These pins are part of the multiplexed external bus interface (MEBI) sub-block and
all interfacing between the MEBI and BDM is done within the core interface boundary. Functional
descriptions of the pins are provided below for completeness.
MC9S12HZ256 Data Sheet, Rev. 2.04
510
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
•
•
•
•
•
BKGD — Background interface pin
TAGHI — High byte instruction tagging pin
TAGLO — Low byte instruction tagging pin
BKGD and TAGHI share the same pin.
TAGLO and LSTRB share the same pin.
NOTE
Generally these pins are shared as described, but it is best to check the
device overview chapter to make certain. All MCUs at the time of this
writing have followed this pin sharing scheme.
18.2.1
BKGD — Background Interface Pin
Debugging control logic communicates with external devices serially via the single-wire background
interface pin (BKGD). During reset, this pin is a mode select input which selects between normal and
special modes of operation. After reset, this pin becomes the dedicated serial interface pin for the
background debug mode.
18.2.2
TAGHI — High Byte Instruction Tagging Pin
This pin is used to tag the high byte of an instruction. When instruction tagging is on, a logic 0 at the falling
edge of the external clock (ECLK) tags the high half of the instruction word being read into the instruction
queue.
18.2.3
TAGLO — Low Byte Instruction Tagging Pin
This pin is used to tag the low byte of an instruction. When instruction tagging is on and low strobe is
enabled, a logic 0 at the falling edge of the external clock (ECLK) tags the low half of the instruction word
being read into the instruction queue.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
511
Chapter 18 Background Debug Module (BDMV4)
18.3
Memory Map and Register Definition
A summary of the registers associated with the BDM is shown in Figure 18-2. Registers are accessed by
host-driven communications to the BDM hardware using READ_BD and WRITE_BD commands.
Detailed descriptions of the registers and associated bits are given in the subsections that follow.
18.3.1
Module Memory Map
Table 18-1. INT Memory Map
Register
Address
Use
Reserved
Access
—
BDM Status Register (BDMSTS)
Reserved
R/W
—
BDM CCR Holding Register (BDMCCR)
R/W
7
BDM Internal Register Position (BDMINR)
R
8–
Reserved
—
MC9S12HZ256 Data Sheet, Rev. 2.04
512
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
18.3.2
Register Descriptions
Register
Name
Bit 7
6
5
4
3
2
1
Bit 0
X
X
X
X
X
X
0
0
SDV
TRACE
UNSEC
0
Reserved
R
W
BDMSTS
R
W
Reserved
R
W
X
X
X
X
X
X
X
X
Reserved
R
W
X
X
X
X
X
X
X
X
Reserved
R
W
X
X
X
X
X
X
X
X
Reserved
R
W
X
X
X
X
X
X
X
X
BDMCCR
R
W
CCR7
CCR6
CCR5
CCR4
CCR3
CCR2
CCR1
CCR0
BDMINR
R
W
0
REG14
REG13
REG12
REG11
0
0
0
Reserved
R
W
0
0
0
0
0
0
0
0
Reserved
R
W
0
0
0
0
0
0
0
0
Reserved
R
W
X
X
X
X
X
X
X
X
Reserved
R
W
X
X
X
X
X
X
X
X
ENBDM
BDMACT
ENTAG
= Unimplemented, Reserved
X
= Indeterminate
CLKSW
= Implemented (do not alter)
0
= Always read zero
Figure 18-2. BDM Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
513
Chapter 18 Background Debug Module (BDMV4)
18.3.2.1
BDM Status Register (BDMSTS)
7
6
R
5
BDMACT
ENBDM
4
3
SDV
TRACE
ENTAG
2
1
0
UNSEC
0
02
0
0
0
0
0
0
0
CLKSW
W
Reset:
Special single-chip mode:
Special peripheral mode:
All other modes:
11
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
0
0
0
0
= Implemented (do not alter)
Figure 18-3. BDM Status Register (BDMSTS)
Note:
1
ENBDM is read as "1" by a debugging environment in Special single-chip mode when the device is not secured or secured
but fully erased (Flash and EEPROM).This is because the ENBDM bit is set by the standard firmware before a BDM command
can be fully transmitted and executed.
2
UNSEC is read as "1" by a debugging environment in Special single-chip mode when the device is secured and fully erased,
else it is "0" and can only be read if not secure (see also bit description).
Read: All modes through BDM operation
Write: All modes but subject to the following:
• BDMACT can only be set by BDM hardware upon entry into BDM. It can only be cleared by the
standard BDM firmware lookup table upon exit from BDM active mode.
• CLKSW can only be written via BDM hardware or standard BDM firmware write commands.
• All other bits, while writable via BDM hardware or standard BDM firmware write commands,
should only be altered by the BDM hardware or standard firmware lookup table as part of BDM
command execution.
• ENBDM should only be set via a BDM hardware command if the BDM firmware commands are
needed. (This does not apply in special single-chip mode).
Table 18-2. BDMSTS Field Descriptions
Field
Description
7
ENBDM
Enable BDM — This bit controls whether the BDM is enabled or disabled. When enabled, BDM can be made
active to allow firmware commands to be executed. When disabled, BDM cannot be made active but BDM
hardware commands are allowed.
0 BDM disabled
1 BDM enabled
Note: ENBDM is set by the firmware immediately out of reset in special single-chip mode. In secure mode, this
bit will not be set by the firmware until after the EEPROM and FLASH erase verify tests are complete.
6
BDMACT
BDM Active Status — This bit becomes set upon entering BDM. The standard BDM firmware lookup table is
then enabled and put into the memory map. BDMACT is cleared by a carefully timed store instruction in the
standard BDM firmware as part of the exit sequence to return to user code and remove the BDM memory from
the map.
0 BDM not active
1 BDM active
MC9S12HZ256 Data Sheet, Rev. 2.04
514
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
Table 18-2. BDMSTS Field Descriptions (continued)
Field
Description
5
ENTAG
Tagging Enable — This bit indicates whether instruction tagging in enabled or disabled. It is set when the
TAGGO command is executed and cleared when BDM is entered. The serial system is disabled and the tag
function enabled 16 cycles after this bit is written. BDM cannot process serial commands while tagging is active.
0 Tagging not enabled or BDM active
1 Tagging enabled
4
SDV
Shift Data Valid — This bit is set and cleared by the BDM hardware. It is set after data has been transmitted as
part of a firmware read command or after data has been received as part of a firmware write command. It is
cleared when the next BDM command has been received or BDM is exited. SDV is used by the standard BDM
firmware to control program flow execution.
0 Data phase of command not complete
1 Data phase of command is complete
3
TRACE
TRACE1 BDM Firmware Command is Being Executed — This bit gets set when a BDM TRACE1 firmware
command is first recognized. It will stay set as long as continuous back-to-back TRACE1 commands are
executed. This bit will get cleared when the next command that is not a TRACE1 command is recognized.
0 TRACE1 command is not being executed
1 TRACE1 command is being executed
2
CLKSW
Clock Switch — The CLKSW bit controls which clock the BDM operates with. It is only writable from a hardware
BDM command. A 150 cycle delay at the clock speed that is active during the data portion of the command will
occur before the new clock source is guaranteed to be active. The start of the next BDM command uses the new
clock for timing subsequent BDM communications.
Table 18-3 shows the resulting BDM clock source based on the CLKSW and the PLLSEL (Pll select from the
clock and reset generator) bits.
Note: The BDM alternate clock source can only be selected when CLKSW = 0 and PLLSEL = 1. The BDM serial
interface is now fully synchronized to the alternate clock source, when enabled. This eliminates frequency
restriction on the alternate clock which was required on previous versions. Refer to the device overview
section to determine which clock connects to the alternate clock source input.
Note: If the acknowledge function is turned on, changing the CLKSW bit will cause the ACK to be at the new rate
for the write command which changes it.
1
UNSEC
Unsecure — This bit is only writable in special single-chip mode from the BDM secure firmware and always gets
reset to zero. It is in a zero state as secure mode is entered so that the secure BDM firmware lookup table is
enabled and put into the memory map along with the standard BDM firmware lookup table.
The secure BDM firmware lookup table verifies that the on-chip EEPROM and FLASH EEPROM are erased. This
being the case, the UNSEC bit is set and the BDM program jumps to the start of the standard BDM firmware
lookup table and the secure BDM firmware lookup table is turned off. If the erase test fails, the UNSEC bit will
not be asserted.
0 System is in a secured mode
1 System is in a unsecured mode
Note: When UNSEC is set, security is off and the user can change the state of the secure bits in the on-chip
FLASH EEPROM. Note that if the user does not change the state of the bits to “unsecured” mode, the
system will be secured again when it is next taken out of reset.
Table 18-3. BDM Clock Sources
PLLSEL
CLKSW
BDMCLK
0
0
Bus clock
0
1
Bus clock
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
515
Chapter 18 Background Debug Module (BDMV4)
Table 18-3. BDM Clock Sources
PLLSEL
CLKSW
BDMCLK
1
0
Alternate clock (refer to the device overview chapter to determine the alternate clock
source)
1
1
Bus clock dependent on the PLL
MC9S12HZ256 Data Sheet, Rev. 2.04
516
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
18.3.2.2
BDM CCR Holding Register (BDMCCR)
7
6
5
4
3
2
1
0
CCR7
CCR6
CCR5
CCR4
CCR3
CCR2
CCR1
CCR0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 18-4. BDM CCR Holding Register (BDMCCR)
Read: All modes
Write: All modes
NOTE
When BDM is made active, the CPU stores the value of the CCR register in
the BDMCCR register. However, out of special single-chip reset, the
BDMCCR is set to 0xD8 and not 0xD0 which is the reset value of the CCR
register.
When entering background debug mode, the BDM CCR holding register is used to save the contents of the
condition code register of the user’s program. It is also used for temporary storage in the standard BDM
firmware mode. The BDM CCR holding register can be written to modify the CCR value.
18.3.2.3
R
BDM Internal Register Position Register (BDMINR)
7
6
5
4
3
2
1
0
0
REG14
REG13
REG12
REG11
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 18-5. BDM Internal Register Position (BDMINR)
Read: All modes
Write: Never
Table 18-4. BDMINR Field Descriptions
Field
Description
6:3
Internal Register Map Position — These four bits show the state of the upper five bits of the base address for
REG[14:11] the system’s relocatable register block. BDMINR is a shadow of the INITRG register which maps the register
block to any 2K byte space within the first 32K bytes of the 64K byte address space.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
517
Chapter 18 Background Debug Module (BDMV4)
18.4
Functional Description
The BDM receives and executes commands from a host via a single wire serial interface. There are two
types of BDM commands, namely, hardware commands and firmware commands.
Hardware commands are used to read and write target system memory locations and to enter active
background debug mode, see Section 18.4.3, “BDM Hardware Commands.” Target system memory
includes all memory that is accessible by the CPU.
Firmware commands are used to read and write CPU resources and to exit from active background debug
mode, see Section 18.4.4, “Standard BDM Firmware Commands.” The CPU resources referred to are the
accumulator (D), X index register (X), Y index register (Y), stack pointer (SP), and program counter (PC).
Hardware commands can be executed at any time and in any mode excluding a few exceptions as
highlighted, see Section 18.4.3, “BDM Hardware Commands.” Firmware commands can only be executed
when the system is in active background debug mode (BDM).
18.4.1
Security
If the user resets into special single-chip mode with the system secured, a secured mode BDM firmware
lookup table is brought into the map overlapping a portion of the standard BDM firmware lookup table.
The secure BDM firmware verifies that the on-chip EEPROM and FLASH EEPROM are erased. This
being the case, the UNSEC bit will get set. The BDM program jumps to the start of the standard BDM
firmware and the secured mode BDM firmware is turned off and all BDM commands are allowed. If the
EEPROM or FLASH do not verify as erased, the BDM firmware sets the ENBDM bit, without asserting
UNSEC, and the firmware enters a loop. This causes the BDM hardware commands to become enabled,
but does not enable the firmware commands. This allows the BDM hardware to be used to erase the
EEPROM and FLASH. After execution of the secure firmware, regardless of the results of the erase tests,
the CPU registers, INITEE and PPAGE, will no longer be in their reset state.
18.4.2
Enabling and Activating BDM
The system must be in active BDM to execute standard BDM firmware commands. BDM can be activated
only after being enabled. BDM is enabled by setting the ENBDM bit in the BDM status (BDMSTS)
register. The ENBDM bit is set by writing to the BDM status (BDMSTS) register, via the single-wire
interface, using a hardware command such as WRITE_BD_BYTE.
After being enabled, BDM is activated by one of the following1:
• Hardware BACKGROUND command
• BDM external instruction tagging mechanism
• CPU BGND instruction
• Breakpoint sub-block’s force or tag mechanism2
When BDM is activated, the CPU finishes executing the current instruction and then begins executing the
firmware in the standard BDM firmware lookup table. When BDM is activated by the breakpoint
1. BDM is enabled and active immediately out of special single-chip reset.
2. This method is only available on systems that have a a breakpoint or a debug sub-block.
MC9S12HZ256 Data Sheet, Rev. 2.04
518
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
sub-block, the type of breakpoint used determines if BDM becomes active before or after execution of the
next instruction.
NOTE
If an attempt is made to activate BDM before being enabled, the CPU
resumes normal instruction execution after a brief delay. If BDM is not
enabled, any hardware BACKGROUND commands issued are ignored by
the BDM and the CPU is not delayed.
In active BDM, the BDM registers and standard BDM firmware lookup table are mapped to addresses
0xFF00 to 0xFFFF. BDM registers are mapped to addresses 0xFF00 to 0xFF07. The BDM uses these
registers which are readable anytime by the BDM. However, these registers are not readable by user
programs.
18.4.3
BDM Hardware Commands
Hardware commands are used to read and write target system memory locations and to enter active
background debug mode. Target system memory includes all memory that is accessible by the CPU such
as on-chip RAM, EEPROM, FLASH EEPROM, I/O and control registers, and all external memory.
Hardware commands are executed with minimal or no CPU intervention and do not require the system to
be in active BDM for execution, although they can continue to be executed in this mode. When executing
a hardware command, the BDM sub-block waits for a free CPU bus cycle so that the background access
does not disturb the running application program. If a free cycle is not found within 128 clock cycles, the
CPU is momentarily frozen so that the BDM can steal a cycle. When the BDM finds a free cycle, the
operation does not intrude on normal CPU operation provided that it can be completed in a single cycle.
However, if an operation requires multiple cycles the CPU is frozen until the operation is complete, even
though the BDM found a free cycle.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
519
Chapter 18 Background Debug Module (BDMV4)
The BDM hardware commands are listed in Table 18-5.
Table 18-5. Hardware Commands
Opcode
(hex)
Data
Description
BACKGROUND
90
None
Enter background mode if firmware is enabled. If enabled, an ACK will
be issued when the part enters active background mode.
ACK_ENABLE
D5
None
Enable handshake. Issues an ACK pulse after the command is
executed.
ACK_DISABLE
D6
None
Disable handshake. This command does not issue an ACK pulse.
READ_BD_BYTE
E4
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table in map.
Odd address data on low byte; even address data on high byte.
READ_BD_WORD
EC
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table in map.
Must be aligned access.
READ_BYTE
E0
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table out of
map. Odd address data on low byte; even address data on high byte.
READ_WORD
E8
16-bit address
16-bit data out
Read from memory with standard BDM firmware lookup table out of
map. Must be aligned access.
WRITE_BD_BYTE
C4
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table in map. Odd
address data on low byte; even address data on high byte.
WRITE_BD_WORD
CC
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table in map. Must
be aligned access.
WRITE_BYTE
C0
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table out of map.
Odd address data on low byte; even address data on high byte.
WRITE_WORD
C8
16-bit address
16-bit data in
Write to memory with standard BDM firmware lookup table out of map.
Must be aligned access.
Command
NOTE:
If enabled, ACK will occur when data is ready for transmission for all BDM READ commands and will occur after the write is
complete for all BDM WRITE commands.
The READ_BD and WRITE_BD commands allow access to the BDM register locations. These locations
are not normally in the system memory map but share addresses with the application in memory. To
distinguish between physical memory locations that share the same address, BDM memory resources are
enabled just for the READ_BD and WRITE_BD access cycle. This allows the BDM to access BDM
locations unobtrusively, even if the addresses conflict with the application memory map.
18.4.4
Standard BDM Firmware Commands
Firmware commands are used to access and manipulate CPU resources. The system must be in active
BDM to execute standard BDM firmware commands, see Section 18.4.2, “Enabling and Activating
BDM.” Normal instruction execution is suspended while the CPU executes the firmware located in the
standard BDM firmware lookup table. The hardware command BACKGROUND is the usual way to
activate BDM.
As the system enters active BDM, the standard BDM firmware lookup table and BDM registers become
visible in the on-chip memory map at 0xFF00–0xFFFF, and the CPU begins executing the standard BDM
MC9S12HZ256 Data Sheet, Rev. 2.04
520
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
firmware. The standard BDM firmware watches for serial commands and executes them as they are
received.
The firmware commands are shown in Table 18-6.
Table 18-6. Firmware Commands
Command1
Opcode (hex)
Data
Description
READ_NEXT
62
16-bit data out
Increment X by 2 (X = X + 2), then read word X points to.
READ_PC
63
16-bit data out
Read program counter.
READ_D
64
16-bit data out
Read D accumulator.
READ_X
65
16-bit data out
Read X index register.
READ_Y
66
16-bit data out
Read Y index register.
READ_SP
67
16-bit data out
Read stack pointer.
WRITE_NEXT
42
16-bit data in
Increment X by 2 (X = X + 2), then write word to location pointed to by X.
WRITE_PC
43
16-bit data in
Write program counter.
WRITE_D
44
16-bit data in
Write D accumulator.
WRITE_X
45
16-bit data in
Write X index register.
WRITE_Y
46
16-bit data in
Write Y index register.
WRITE_SP
47
16-bit data in
Write stack pointer.
GO
08
None
Go to user program. If enabled, ACK will occur when leaving active
background mode.
GO_UNTIL2
0C
None
Go to user program. If enabled, ACK will occur upon returning to active
background mode.
TRACE1
10
None
Execute one user instruction then return to active BDM. If enabled, ACK
will occur upon returning to active background mode.
TAGGO
18
None
Enable tagging and go to user program. There is no ACK pulse related to
this command.
1
If enabled, ACK will occur when data is ready for transmission for all BDM READ commands and will occur after the write is
complete for all BDM WRITE commands.
2
Both WAIT (with clocks to the S12 CPU core disabled) and STOP disable the ACK function. The GO_UNTIL command will not
get an Acknowledge if one of these two CPU instructions occurs before the “UNTIL” instruction. This can be a problem for any
instruction that uses ACK, but GO_UNTIL is a lot more difficult for the development tool to time-out.
18.4.5
BDM Command Structure
Hardware and firmware BDM commands start with an 8-bit opcode followed by a 16-bit address and/or a
16-bit data word depending on the command. All the read commands return 16 bits of data despite the byte
or word implication in the command name.
NOTE
8-bit reads return 16-bits of data, of which, only one byte will contain valid
data. If reading an even address, the valid data will appear in the MSB. If
reading an odd address, the valid data will appear in the LSB.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
521
Chapter 18 Background Debug Module (BDMV4)
NOTE
16-bit misaligned reads and writes are not allowed. If attempted, the BDM
will ignore the least significant bit of the address and will assume an even
address from the remaining bits.
For hardware data read commands, the external host must wait 150 bus clock cycles after sending the
address before attempting to obtain the read data. This is to be certain that valid data is available in the
BDM shift register, ready to be shifted out. For hardware write commands, the external host must wait
150 bus clock cycles after sending the data to be written before attempting to send a new command. This
is to avoid disturbing the BDM shift register before the write has been completed. The 150 bus clock cycle
delay in both cases includes the maximum 128 cycle delay that can be incurred as the BDM waits for a
free cycle before stealing a cycle.
For firmware read commands, the external host should wait 44 bus clock cycles after sending the command
opcode and before attempting to obtain the read data. This includes the potential of an extra 7 cycles when
the access is external with a narrow bus access (+1 cycle) and / or a stretch (+1, 2, or 3 cycles), (7 cycles
could be needed if both occur). The 44 cycle wait allows enough time for the requested data to be made
available in the BDM shift register, ready to be shifted out.
NOTE
This timing has increased from previous BDM modules due to the new
capability in which the BDM serial interface can potentially run faster than
the bus. On previous BDM modules this extra time could be hidden within
the serial time.
For firmware write commands, the external host must wait 32 bus clock cycles after sending the data to be
written before attempting to send a new command. This is to avoid disturbing the BDM shift register
before the write has been completed.
The external host should wait 64 bus clock cycles after a TRACE1 or GO command before starting any
new serial command. This is to allow the CPU to exit gracefully from the standard BDM firmware lookup
table and resume execution of the user code. Disturbing the BDM shift register prematurely may adversely
affect the exit from the standard BDM firmware lookup table.
NOTE
If the bus rate of the target processor is unknown or could be changing, it is
recommended that the ACK (acknowledge function) be used to indicate
when an operation is complete. When using ACK, the delay times are
automated.
Figure 18-6 represents the BDM command structure. The command blocks illustrate a series of eight bit
times starting with a falling edge. The bar across the top of the blocks indicates that the BKGD line idles
in the high state. The time for an 8-bit command is 8 × 16 target clock cycles.1
1. Target clock cycles are cycles measured using the target MCU’s serial clock rate. See Section 18.4.6, “BDM Serial Interface,”
and Section 18.3.2.1, “BDM Status Register (BDMSTS),” for information on how serial clock rate is selected.
MC9S12HZ256 Data Sheet, Rev. 2.04
522
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
HARDWARE
READ
8 BITS
AT ∼16 TC/BIT
16 BITS
AT ∼16 TC/BIT
COMMAND
ADDRESS
150-BC
DELAY
16 BITS
AT ∼16 TC/BIT
DATA
NEXT
COMMAND
150-BC
DELAY
HARDWARE
WRITE
COMMAND
ADDRESS
DATA
NEXT
COMMAND
44-BC
DELAY
FIRMWARE
READ
COMMAND
NEXT
COMMAND
DATA
32-BC
DELAY
FIRMWARE
WRITE
COMMAND
DATA
NEXT
COMMAND
64-BC
DELAY
GO,
TRACE
COMMAND
NEXT
COMMAND
BC = BUS CLOCK CYCLES
TC = TARGET CLOCK CYCLES
Figure 18-6. BDM Command Structure
18.4.6
BDM Serial Interface
The BDM communicates with external devices serially via the BKGD pin. During reset, this pin is a mode
select input which selects between normal and special modes of operation. After reset, this pin becomes
the dedicated serial interface pin for the BDM.
The BDM serial interface is timed using the clock selected by the CLKSW bit in the status register see
Section 18.3.2.1, “BDM Status Register (BDMSTS).” This clock will be referred to as the target clock in
the following explanation.
The BDM serial interface uses a clocking scheme in which the external host generates a falling edge on
the BKGD pin to indicate the start of each bit time. This falling edge is sent for every bit whether data is
transmitted or received. Data is transferred most significant bit (MSB) first at 16 target clock cycles per
bit. The interface times out if 512 clock cycles occur between falling edges from the host.
The BKGD pin is a pseudo open-drain pin and has an weak on-chip active pull-up that is enabled at all
times. It is assumed that there is an external pull-up and that drivers connected to BKGD do not typically
drive the high level. Because R-C rise time could be unacceptably long, the target system and host provide
brief driven-high (speedup) pulses to drive BKGD to a logic 1. The source of this speedup pulse is the host
for transmit cases and the target for receive cases.
The timing for host-to-target is shown in Figure 18-7 and that of target-to-host in Figure 18-8 and
Figure 18-9. All four cases begin when the host drives the BKGD pin low to generate a falling edge.
Because the host and target are operating from separate clocks, it can take the target system up to one full
clock cycle to recognize this edge. The target measures delays from this perceived start of the bit time
while the host measures delays from the point it actually drove BKGD low to start the bit up to one target
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
523
Chapter 18 Background Debug Module (BDMV4)
clock cycle earlier. Synchronization between the host and target is established in this manner at the start
of every bit time.
Figure 18-7 shows an external host transmitting a logic 1 and transmitting a logic 0 to the BKGD pin of a
target system. The host is asynchronous to the target, so there is up to a one clock-cycle delay from the
host-generated falling edge to where the target recognizes this edge as the beginning of the bit time. Ten
target clock cycles later, the target senses the bit level on the BKGD pin. Internal glitch detect logic
requires the pin be driven high no later that eight target clock cycles after the falling edge for a logic 1
transmission.
Because the host drives the high speedup pulses in these two cases, the rising edges look like digitally
driven signals.
CLOCK
TARGET SYSTEM
HOST
TRANSMIT 1
HOST
TRANSMIT 0
PERCEIVED
START OF BIT TIME
TARGET SENSES BIT
10 CYCLES
SYNCHRONIZATION
UNCERTAINTY
EARLIEST
START OF
NEXT BIT
Figure 18-7. BDM Host-to-Target Serial Bit Timing
The receive cases are more complicated. Figure 18-8 shows the host receiving a logic 1 from the target
system. Because the host is asynchronous to the target, there is up to one clock-cycle delay from the
host-generated falling edge on BKGD to the perceived start of the bit time in the target. The host holds the
BKGD pin low long enough for the target to recognize it (at least two target clock cycles). The host must
release the low drive before the target drives a brief high speedup pulse seven target clock cycles after the
perceived start of the bit time. The host should sample the bit level about 10 target clock cycles after it
started the bit time.
MC9S12HZ256 Data Sheet, Rev. 2.04
524
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
CLOCK
TARGET SYSTEM
HOST
DRIVE TO
BKGD PIN
TARGET SYSTEM
SPEEDUP
PULSE
HIGH-IMPEDANCE
HIGH-IMPEDANCE
HIGH-IMPEDANCE
PERCEIVED
START OF BIT TIME
R-C RISE
BKGD PIN
10 CYCLES
10 CYCLES
HOST SAMPLES
BKGD PIN
EARLIEST
START OF
NEXT BIT
Figure 18-8. BDM Target-to-Host Serial Bit Timing (Logic 1)
Figure 18-9 shows the host receiving a logic 0 from the target. Because the host is asynchronous to the
target, there is up to a one clock-cycle delay from the host-generated falling edge on BKGD to the start of
the bit time as perceived by the target. The host initiates the bit time but the target finishes it. Because the
target wants the host to receive a logic 0, it drives the BKGD pin low for 13 target clock cycles then briefly
drives it high to speed up the rising edge. The host samples the bit level about 10 target clock cycles after
starting the bit time.
CLOCK
TARGET SYS.
HOST
DRIVE TO
BKGD PIN
HIGH-IMPEDANCE
SPEEDUP PULSE
TARGET SYS.
DRIVE AND
SPEEDUP PULSE
PERCEIVED
START OF BIT TIME
BKGD PIN
10 CYCLES
10 CYCLES
HOST SAMPLES
BKGD PIN
EARLIEST
START OF
NEXT BIT
Figure 18-9. BDM Target-to-Host Serial Bit Timing (Logic 0)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
525
Chapter 18 Background Debug Module (BDMV4)
18.4.7
Serial Interface Hardware Handshake Protocol
BDM commands that require CPU execution are ultimately treated at the MCU bus rate. Because the BDM
clock source can be asynchronously related to the bus frequency, when CLKSW = 0, it is very helpful to
provide a handshake protocol in which the host could determine when an issued command is executed by
the CPU. The alternative is to always wait the amount of time equal to the appropriate number of cycles at
the slowest possible rate the clock could be running. This sub-section will describe the hardware
handshake protocol.
The hardware handshake protocol signals to the host controller when an issued command was successfully
executed by the target. This protocol is implemented by a 16 serial clock cycle low pulse followed by a
brief speedup pulse in the BKGD pin. This pulse is generated by the target MCU when a command, issued
by the host, has been successfully executed (see Figure 18-10). This pulse is referred to as the ACK pulse.
After the ACK pulse has finished: the host can start the bit retrieval if the last issued command was a read
command, or start a new command if the last command was a write command or a control command
(BACKGROUND, GO, GO_UNTIL, or TRACE1). The ACK pulse is not issued earlier than 32 serial
clock cycles after the BDM command was issued. The end of the BDM command is assumed to be the
16th tick of the last bit. This minimum delay assures enough time for the host to perceive the ACK pulse.
Note also that, there is no upper limit for the delay between the command and the related ACK pulse,
because the command execution depends upon the CPU bus frequency, which in some cases could be very
slow compared to the serial communication rate. This protocol allows a great flexibility for the POD
designers, because it does not rely on any accurate time measurement or short response time to any event
in the serial communication.
BDM CLOCK
(TARGET MCU)
16 CYCLES
TARGET
TRANSMITS
ACK PULSE
HIGH-IMPEDANCE
HIGH-IMPEDANCE
32 CYCLES
SPEEDUP PULSE
MINIMUM DELAY
FROM THE BDM COMMAND
BKGD PIN
EARLIEST
START OF
NEXT BIT
16th TICK OF THE
LAST COMMAD BIT
Figure 18-10. Target Acknowledge Pulse (ACK)
NOTE
If the ACK pulse was issued by the target, the host assumes the previous
command was executed. If the CPU enters WAIT or STOP prior to
executing a hardware command, the ACK pulse will not be issued meaning
that the BDM command was not executed. After entering wait or stop mode,
the BDM command is no longer pending.
MC9S12HZ256 Data Sheet, Rev. 2.04
526
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
Figure 18-11 shows the ACK handshake protocol in a command level timing diagram. The READ_BYTE
instruction is used as an example. First, the 8-bit instruction opcode is sent by the host, followed by the
address of the memory location to be read. The target BDM decodes the instruction. A bus cycle is grabbed
(free or stolen) by the BDM and it executes the READ_BYTE operation. Having retrieved the data, the
BDM issues an ACK pulse to the host controller, indicating that the addressed byte is ready to be retrieved.
After detecting the ACK pulse, the host initiates the byte retrieval process. Note that data is sent in the form
of a word and the host needs to determine which is the appropriate byte based on whether the address was
odd or even.
TARGET
BKGD PIN
READ_BYTE
HOST
BYTE ADDRESS
HOST
(2) BYTES ARE
RETRIEVED
NEW BDM
COMMAND
HOST
TARGET
BDM DECODES
THE COMMAND
TARGET
BDM ISSUES THE
ACK PULSE (OUT OF SCALE)
BDM EXECUTES THE
READ_BYTE COMMAND
Figure 18-11. Handshake Protocol at Command Level
Differently from the normal bit transfer (where the host initiates the transmission), the serial interface ACK
handshake pulse is initiated by the target MCU by issuing a falling edge in the BKGD pin. The hardware
handshake protocol in Figure 18-10 specifies the timing when the BKGD pin is being driven, so the host
should follow this timing constraint in order to avoid the risk of an electrical conflict in the BKGD pin.
NOTE
The only place the BKGD pin can have an electrical conflict is when one
side is driving low and the other side is issuing a speedup pulse (high). Other
“highs” are pulled rather than driven. However, at low rates the time of the
speedup pulse can become lengthy and so the potential conflict time
becomes longer as well.
The ACK handshake protocol does not support nested ACK pulses. If a BDM command is not
acknowledge by an ACK pulse, the host needs to abort the pending command first in order to be able to
issue a new BDM command. When the CPU enters WAIT or STOP while the host issues a command that
requires CPU execution (e.g., WRITE_BYTE), the target discards the incoming command due to the
WAIT or STOP being detected. Therefore, the command is not acknowledged by the target, which means
that the ACK pulse will not be issued in this case. After a certain time the host should decide to abort the
ACK sequence in order to be free to issue a new command. Therefore, the protocol should provide a
mechanism in which a command, and therefore a pending ACK, could be aborted.
NOTE
Differently from a regular BDM command, the ACK pulse does not provide
a time out. This means that in the case of a WAIT or STOP instruction being
executed, the ACK would be prevented from being issued. If not aborted, the
ACK would remain pending indefinitely. See the handshake abort procedure
described in Section 18.4.8, “Hardware Handshake Abort Procedure.”
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
527
Chapter 18 Background Debug Module (BDMV4)
18.4.8
Hardware Handshake Abort Procedure
The abort procedure is based on the SYNC command. In order to abort a command, which had not issued
the corresponding ACK pulse, the host controller should generate a low pulse in the BKGD pin by driving
it low for at least 128 serial clock cycles and then driving it high for one serial clock cycle, providing a
speedup pulse. By detecting this long low pulse in the BKGD pin, the target executes the SYNC protocol,
see Section 18.4.9, “SYNC — Request Timed Reference Pulse,” and assumes that the pending command
and therefore the related ACK pulse, are being aborted. Therefore, after the SYNC protocol has been
completed the host is free to issue new BDM commands.
Although it is not recommended, the host could abort a pending BDM command by issuing a low pulse in
the BKGD pin shorter than 128 serial clock cycles, which will not be interpreted as the SYNC command.
The ACK is actually aborted when a falling edge is perceived by the target in the BKGD pin. The short
abort pulse should have at least 4 clock cycles keeping the BKGD pin low, in order to allow the falling
edge to be detected by the target. In this case, the target will not execute the SYNC protocol but the pending
command will be aborted along with the ACK pulse. The potential problem with this abort procedure is
when there is a conflict between the ACK pulse and the short abort pulse. In this case, the target may not
perceive the abort pulse. The worst case is when the pending command is a read command (i.e.,
READ_BYTE). If the abort pulse is not perceived by the target the host will attempt to send a new
command after the abort pulse was issued, while the target expects the host to retrieve the accessed
memory byte. In this case, host and target will run out of synchronism. However, if the command to be
aborted is not a read command the short abort pulse could be used. After a command is aborted the target
assumes the next falling edge, after the abort pulse, is the first bit of a new BDM command.
NOTE
The details about the short abort pulse are being provided only as a reference
for the reader to better understand the BDM internal behavior. It is not
recommended that this procedure be used in a real application.
Because the host knows the target serial clock frequency, the SYNC command (used to abort a command)
does not need to consider the lower possible target frequency. In this case, the host could issue a SYNC
very close to the 128 serial clock cycles length. Providing a small overhead on the pulse length in order to
assure the SYNC pulse will not be misinterpreted by the target. See Section 18.4.9, “SYNC — Request
Timed Reference Pulse.”
Figure 18-12 shows a SYNC command being issued after a READ_BYTE, which aborts the
READ_BYTE command. Note that, after the command is aborted a new command could be issued by the
host computer.
NOTE
Figure 18-12 does not represent the signals in a true timing scale
MC9S12HZ256 Data Sheet, Rev. 2.04
528
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
READ_BYTE CMD IS ABORTED
BY THE SYNC REQUEST
(OUT OF SCALE)
BKGD PIN
READ_BYTE
SYNC RESPONSE
FROM THE TARGET
(OUT OF SCALE)
MEMORY ADDRESS
HOST
READ_STATUS
TARGET
HOST
BDM DECODE
AND STARTS TO EXECUTES
THE READ_BYTE CMD
TARGET
NEW BDM COMMAND
HOST
TARGET
NEW BDM COMMAND
Figure 18-12. ACK Abort Procedure at the Command Level
Figure 18-13 shows a conflict between the ACK pulse and the SYNC request pulse. This conflict could
occur if a POD device is connected to the target BKGD pin and the target is already in debug active mode.
Consider that the target CPU is executing a pending BDM command at the exact moment the POD is being
connected to the BKGD pin. In this case, an ACK pulse is issued along with the SYNC command. In this
case, there is an electrical conflict between the ACK speedup pulse and the SYNC pulse. Because this is
not a probable situation, the protocol does not prevent this conflict from happening.
AT LEAST 128 CYCLES
BDM CLOCK
(TARGET MCU)
ACK PULSE
TARGET MCU
DRIVES TO
BKGD PIN
HIGH-IMPEDANCE
ELECTRICAL CONFLICT
HOST AND
TARGET DRIVE
TO BKGD PIN
HOST
DRIVES SYNC
TO BKGD PIN
SPEEDUP PULSE
HOST SYNC REQUEST PULSE
BKGD PIN
16 CYCLES
Figure 18-13. ACK Pulse and SYNC Request Conflict
NOTE
This information is being provided so that the MCU integrator will be aware
that such a conflict could eventually occur.
The hardware handshake protocol is enabled by the ACK_ENABLE and disabled by the ACK_DISABLE
BDM commands. This provides backwards compatibility with the existing POD devices which are not
able to execute the hardware handshake protocol. It also allows for new POD devices, that support the
hardware handshake protocol, to freely communicate with the target device. If desired, without the need
for waiting for the ACK pulse.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
529
Chapter 18 Background Debug Module (BDMV4)
The commands are described as follows:
• ACK_ENABLE — enables the hardware handshake protocol. The target will issue the ACK pulse
when a CPU command is executed by the CPU. The ACK_ENABLE command itself also has the
ACK pulse as a response.
• ACK_DISABLE — disables the ACK pulse protocol. In this case, the host needs to use the worst
case delay time at the appropriate places in the protocol.
The default state of the BDM after reset is hardware handshake protocol disabled.
All the read commands will ACK (if enabled) when the data bus cycle has completed and the data is then
ready for reading out by the BKGD serial pin. All the write commands will ACK (if enabled) after the data
has been received by the BDM through the BKGD serial pin and when the data bus cycle is complete. See
Section 18.4.3, “BDM Hardware Commands,” and Section 18.4.4, “Standard BDM Firmware
Commands,” for more information on the BDM commands.
The ACK_ENABLE sends an ACK pulse when the command has been completed. This feature could be
used by the host to evaluate if the target supports the hardware handshake protocol. If an ACK pulse is
issued in response to this command, the host knows that the target supports the hardware handshake
protocol. If the target does not support the hardware handshake protocol the ACK pulse is not issued. In
this case, the ACK_ENABLE command is ignored by the target because it is not recognized as a valid
command.
The BACKGROUND command will issue an ACK pulse when the CPU changes from normal to
background mode. The ACK pulse related to this command could be aborted using the SYNC command.
The GO command will issue an ACK pulse when the CPU exits from background mode. The ACK pulse
related to this command could be aborted using the SYNC command.
The GO_UNTIL command is equivalent to a GO command with exception that the ACK pulse, in this
case, is issued when the CPU enters into background mode. This command is an alternative to the GO
command and should be used when the host wants to trace if a breakpoint match occurs and causes the
CPU to enter active background mode. Note that the ACK is issued whenever the CPU enters BDM, which
could be caused by a breakpoint match or by a BGND instruction being executed. The ACK pulse related
to this command could be aborted using the SYNC command.
The TRACE1 command has the related ACK pulse issued when the CPU enters background active mode
after one instruction of the application program is executed. The ACK pulse related to this command could
be aborted using the SYNC command.
The TAGGO command will not issue an ACK pulse because this would interfere with the tagging function
shared on the same pin.
MC9S12HZ256 Data Sheet, Rev. 2.04
530
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
18.4.9
SYNC — Request Timed Reference Pulse
The SYNC command is unlike other BDM commands because the host does not necessarily know the
correct communication speed to use for BDM communications until after it has analyzed the response to
the SYNC command. To issue a SYNC command, the host should perform the following steps:
1. Drive the BKGD pin low for at least 128 cycles at the lowest possible BDM serial communication
frequency (the lowest serial communication frequency is determined by the crystal oscillator or the
clock chosen by CLKSW.)
2. Drive BKGD high for a brief speedup pulse to get a fast rise time (this speedup pulse is typically
one cycle of the host clock.)
3. Remove all drive to the BKGD pin so it reverts to high impedance.
4. Listen to the BKGD pin for the sync response pulse.
Upon detecting the SYNC request from the host, the target performs the following steps:
1. Discards any incomplete command received or bit retrieved.
2. Waits for BKGD to return to a logic 1.
3. Delays 16 cycles to allow the host to stop driving the high speedup pulse.
4. Drives BKGD low for 128 cycles at the current BDM serial communication frequency.
5. Drives a one-cycle high speedup pulse to force a fast rise time on BKGD.
6. Removes all drive to the BKGD pin so it reverts to high impedance.
The host measures the low time of this 128 cycle SYNC response pulse and determines the correct speed
for subsequent BDM communications. Typically, the host can determine the correct communication speed
within a few percent of the actual target speed and the communication protocol can easily tolerate speed
errors of several percent.
As soon as the SYNC request is detected by the target, any partially received command or bit retrieved is
discarded. This is referred to as a soft-reset, equivalent to a time-out in the serial communication. After the
SYNC response, the target will consider the next falling edge (issued by the host) as the start of a new
BDM command or the start of new SYNC request.
Another use of the SYNC command pulse is to abort a pending ACK pulse. The behavior is exactly the
same as in a regular SYNC command. Note that one of the possible causes for a command to not be
acknowledged by the target is a host-target synchronization problem. In this case, the command may not
have been understood by the target and so an ACK response pulse will not be issued.
18.4.10 Instruction Tracing
When a TRACE1 command is issued to the BDM in active BDM, the CPU exits the standard BDM
firmware and executes a single instruction in the user code. As soon as this has occurred, the CPU is forced
to return to the standard BDM firmware and the BDM is active and ready to receive a new command. If
the TRACE1 command is issued again, the next user instruction will be executed. This facilitates stepping
or tracing through the user code one instruction at a time.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
531
Chapter 18 Background Debug Module (BDMV4)
If an interrupt is pending when a TRACE1 command is issued, the interrupt stacking operation occurs but
no user instruction is executed. Upon return to standard BDM firmware execution, the program counter
points to the first instruction in the interrupt service routine.
18.4.11 Instruction Tagging
The instruction queue and cycle-by-cycle CPU activity are reconstructible in real time or from trace history
that is captured by a logic analyzer. However, the reconstructed queue cannot be used to stop the CPU at
a specific instruction. This is because execution already has begun by the time an operation is visible
outside the system. A separate instruction tagging mechanism is provided for this purpose.
The tag follows program information as it advances through the instruction queue. When a tagged
instruction reaches the head of the queue, the CPU enters active BDM rather than executing the instruction.
NOTE
Tagging is disabled when BDM becomes active and BDM serial commands
are not processed while tagging is active.
Executing the BDM TAGGO command configures two system pins for tagging. The TAGLO signal shares
a pin with the LSTRB signal, and the TAGHI signal shares a pin with the BKGD signal.
Table 18-7 shows the functions of the two tagging pins. The pins operate independently, that is the state of
one pin does not affect the function of the other. The presence of logic level 0 on either pin at the fall of
the external clock (ECLK) performs the indicated function. High tagging is allowed in all modes. Low
tagging is allowed only when low strobe is enabled (LSTRB is allowed only in wide expanded modes and
emulation expanded narrow mode).
Table 18-7. Tag Pin Function
TAGHI
TAGLO
Tag
1
1
No tag
1
0
Low byte
0
1
High byte
0
0
Both bytes
18.4.12 Serial Communication Time-Out
The host initiates a host-to-target serial transmission by generating a falling edge on the BKGD pin. If
BKGD is kept low for more than 128 target clock cycles, the target understands that a SYNC command
was issued. In this case, the target will keep waiting for a rising edge on BKGD in order to answer the
SYNC request pulse. If the rising edge is not detected, the target will keep waiting forever without any
time-out limit.
Consider now the case where the host returns BKGD to logic one before 128 cycles. This is interpreted as
a valid bit transmission, and not as a SYNC request. The target will keep waiting for another falling edge
marking the start of a new bit. If, however, a new falling edge is not detected by the target within 512 clock
cycles since the last falling edge, a time-out occurs and the current command is discarded without affecting
memory or the operating mode of the MCU. This is referred to as a soft-reset.
MC9S12HZ256 Data Sheet, Rev. 2.04
532
Freescale Semiconductor
Chapter 18 Background Debug Module (BDMV4)
If a read command is issued but the data is not retrieved within 512 serial clock cycles, a soft-reset will
occur causing the command to be disregarded. The data is not available for retrieval after the time-out has
occurred. This is the expected behavior if the handshake protocol is not enabled. However, consider the
behavior where the BDC is running in a frequency much greater than the CPU frequency. In this case, the
command could time out before the data is ready to be retrieved. In order to allow the data to be retrieved
even with a large clock frequency mismatch (between BDC and CPU) when the hardware handshake
protocol is enabled, the time out between a read command and the data retrieval is disabled. Therefore, the
host could wait for more then 512 serial clock cycles and continue to be able to retrieve the data from an
issued read command. However, as soon as the handshake pulse (ACK pulse) is issued, the time-out feature
is re-activated, meaning that the target will time out after 512 clock cycles. Therefore, the host needs to
retrieve the data within a 512 serial clock cycles time frame after the ACK pulse had been issued. After
that period, the read command is discarded and the data is no longer available for retrieval. Any falling
edge of the BKGD pin after the time-out period is considered to be a new command or a SYNC request.
Note that whenever a partially issued command, or partially retrieved data, has occurred the time out in the
serial communication is active. This means that if a time frame higher than 512 serial clock cycles is
observed between two consecutive negative edges and the command being issued or data being retrieved
is not complete, a soft-reset will occur causing the partially received command or data retrieved to be
disregarded. The next falling edge of the BKGD pin, after a soft-reset has occurred, is considered by the
target as the start of a new BDM command, or the start of a SYNC request pulse.
18.4.13 Operation in Wait Mode
The BDM cannot be used in wait mode if the system disables the clocks to the BDM.
There is a clearing mechanism associated with the WAIT instruction when the clocks to the BDM (CPU
core platform) are disabled. As the clocks restart from wait mode, the BDM receives a soft reset (clearing
any command in progress) and the ACK function will be disabled. This is a change from previous BDM
modules.
18.4.14 Operation in Stop Mode
The BDM is completely shutdown in stop mode.
There is a clearing mechanism associated with the STOP instruction. STOP must be enabled and the part
must go into stop mode for this to occur. As the clocks restart from stop mode, the BDM receives a soft
reset (clearing any command in progress) and the ACK function will be disabled. This is a change from
previous BDM modules.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
533
Chapter 18 Background Debug Module (BDMV4)
MC9S12HZ256 Data Sheet, Rev. 2.04
534
Freescale Semiconductor
Chapter 19
Debug Module (DBGV1)
19.1
Introduction
This section describes the functionality of the debug (DBG) sub-block of the HCS12 core platform.
The DBG module is designed to be fully compatible with the existing BKP_HCS12_A module (BKP
mode) and furthermore provides an on-chip trace buffer with flexible triggering capability (DBG mode).
The DBG module provides for non-intrusive debug of application software. The DBG module is optimized
for the HCS12 16-bit architecture.
19.1.1
Features
The DBG module in BKP mode includes these distinctive features:
• Full or dual breakpoint mode
— Compare on address and data (full)
— Compare on either of two addresses (dual)
• BDM or SWI breakpoint
— Enter BDM on breakpoint (BDM)
— Execute SWI on breakpoint (SWI)
• Tagged or forced breakpoint
— Break just before a specific instruction will begin execution (TAG)
— Break on the first instruction boundary after a match occurs (Force)
• Single, range, or page address compares
— Compare on address (single)
— Compare on address 256 byte (range)
— Compare on any 16K page (page)
• At forced breakpoints compare address on read or write
• High and/or low byte data compares
• Comparator C can provide an additional tag or force breakpoint (enhancement for BKP mode)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
535
Chapter 19 Debug Module (DBGV1)
The DBG in DBG mode includes these distinctive features:
• Three comparators (A, B, and C)
— Dual mode, comparators A and B used to compare addresses
— Full mode, comparator A compares address and comparator B compares data
— Can be used as trigger and/or breakpoint
— Comparator C used in LOOP1 capture mode or as additional breakpoint
• Four capture modes
— Normal mode, change-of-flow information is captured based on trigger specification
— Loop1 mode, comparator C is dynamically updated to prevent redundant change-of-flow
storage.
— Detail mode, address and data for all cycles except program fetch (P) and free (f) cycles are
stored in trace buffer
— Profile mode, last instruction address executed by CPU is returned when trace buffer address is
read
• Two types of breakpoint or debug triggers
— Break just before a specific instruction will begin execution (tag)
— Break on the first instruction boundary after a match occurs (force)
• BDM or SWI breakpoint
— Enter BDM on breakpoint (BDM)
— Execute SWI on breakpoint (SWI)
• Nine trigger modes for comparators A and B
— A
— A or B
— A then B
— A and B, where B is data (full mode)
— A and not B, where B is data (full mode)
— Event only B, store data
— A then event only B, store data
— Inside range, A ≤ address ≤ B
— Outside range, address < Α or address > B
• Comparator C provides an additional tag or force breakpoint when capture mode is not configured
in LOOP1 mode.
• Sixty-four word (16 bits wide) trace buffer for storing change-of-flow information, event only data
and other bus information.
— Source address of taken conditional branches (long, short, bit-conditional, and loop constructs)
— Destination address of indexed JMP, JSR, and CALL instruction.
— Destination address of RTI, RTS, and RTC instructions
— Vector address of interrupts, except for SWI and BDM vectors
MC9S12HZ256 Data Sheet, Rev. 2.04
536
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
—
—
—
—
19.1.2
Data associated with event B trigger modes
Detail report mode stores address and data for all cycles except program (P) and free (f) cycles
Current instruction address when in profiling mode
BGND is not considered a change-of-flow (cof) by the debugger
Modes of Operation
There are two main modes of operation: breakpoint mode and debug mode. Each one is mutually exclusive
of the other and selected via a software programmable control bit.
In the breakpoint mode there are two sub-modes of operation:
• Dual address mode, where a match on either of two addresses will cause the system to enter
background debug mode (BDM) or initiate a software interrupt (SWI).
• Full breakpoint mode, where a match on address and data will cause the system to enter
background debug mode (BDM) or initiate a software interrupt (SWI).
In debug mode, there are several sub-modes of operation.
• Trigger modes
There are many ways to create a logical trigger. The trigger can be used to capture bus information
either starting from the trigger or ending at the trigger. Types of triggers (A and B are registers):
— A only
— A or B
— A then B
— Event only B (data capture)
— A then event only B (data capture)
— A and B, full mode
— A and not B, full mode
— Inside range
— Outside range
• Capture modes
There are several capture modes. These determine which bus information is saved and which is
ignored.
— Normal: save change-of-flow program fetches
— Loop1: save change-of-flow program fetches, ignoring duplicates
— Detail: save all bus operations except program and free cycles
— Profile: poll target from external device
19.1.3
Block Diagram
Figure 19-1 is a block diagram of this module in breakpoint mode. Figure 19-2 is a block diagram of this
module in debug mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
537
Chapter 19 Debug Module (DBGV1)
CLOCKS AND
CONTROL SIGNALS
BKP CONTROL
SIGNALS
CONTROL BLOCK
BREAKPOINT MODES
AND GENERATION OF SWI,
FORCE BDM, AND TAGS
......
RESULTS SIGNALS
CONTROL SIGNALS
READ/WRITE
CONTROL
CONTROL BITS
......
EXPANSION ADDRESS
ADDRESS
WRITE DATA
READ DATA
REGISTER BLOCK
BKPCT0
BKPCT1
COMPARE BLOCK
BKP READ
DATA BUS
WRITE
DATA BUS
EXPANSION ADDRESSES
BKP0X
COMPARATOR
BKP0H
COMPARATOR
BKP0L
COMPARATOR
BKP1X
COMPARATOR
BKP1H
COMPARATOR
DATA/ADDRESS
HIGH MUX
COMPARATOR
DATA/ADDRESS
LOW MUX
ADDRESS HIGH
ADDRESS LOW
EXPANSION ADDRESSES
DATA HIGH
BKP1L
ADDRESS HIGH
DATA LOW
ADDRESS LOW
READ DATA HIGH
COMPARATOR
READ DATA LOW
COMPARATOR
Figure 19-1. DBG Block Diagram in BKP Mode
MC9S12HZ256 Data Sheet, Rev. 2.04
538
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
DBG READ DATA BUS
ADDRESS BUS
ADDRESS/DATA/CONTROL
REGISTERS
CONTROL
WRITE DATA BUS
READ DATA BUS
READ/WRITE
TRACER
BUFFER
CONTROL
LOGIC
MATCH_A
COMPARATOR A
MATCH_B
COMPARATOR B
DBG MODE ENABLE
CONTROL
MATCH_C
LOOP1
COMPARATOR C
TAG
FORCE
CHANGE-OF-FLOW
INDICATORS
MCU IN BDM
DETAIL
EVENT ONLY
STORE
CPU PROGRAM COUNTER
POINTER
INSTRUCTION
LAST CYCLE
M
U
X
REGISTER
BUS CLOCK
WRITE DATA BUS
M
U
X
READ DATA BUS
M
U
X
LAST
INSTRUCTION
ADDRESS
PROFILE CAPTURE MODE
64 x 16 BIT
WORD
TRACE
BUFFER
M
U
X
TRACE BUFFER
OR PROFILING DATA
PROFILE
CAPTURE
REGISTER
READ/WRITE
Figure 19-2. DBG Block Diagram in DBG Mode
19.2
External Signal Description
The DBG sub-module relies on the external bus interface (generally the MEBI) when the DBG is matching
on the external bus.
The tag pins in Table 19-1 (part of the MEBI) may also be a part of the breakpoint operation.
Table 19-1. External System Pins Associated with DBG and MEBI
Pin Name
Pin Functions
Description
BKGD/MODC/
TAGHI
TAGHI
When instruction tagging is on, a 0 at the falling edge of E tags the high half of the
instruction word being read into the instruction queue.
PE3/LSTRB/ TAGLO
TAGLO
In expanded wide mode or emulation narrow modes, when instruction tagging is on
and low strobe is enabled, a 0 at the falling edge of E tags the low half of the
instruction word being read into the instruction queue.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
539
Chapter 19 Debug Module (DBGV1)
19.3
Memory Map and Register Definition
A summary of the registers associated with the DBG sub-block is shown in Figure 19-3. Detailed
descriptions of the registers and bits are given in the subsections that follow.
19.3.1
Module Memory Map
Table 19-2. DBG Memory Map
Address
Offset
19.3.2
Use
Access
Debug Control Register (DBGC1)
R/W
Debug Status and Control Register (DBGSC)
R/W
Debug Trace Buffer Register High (DBGTBH)
R
Debug Trace Buffer Register Low (DBGTBL)
R
4
Debug Count Register (DBGCNT)
5
Debug Comparator C Extended Register (DBGCCX)
R/W
R
6
Debug Comparator C Register High (DBGCCH)
R/W
Debug Comparator C Register Low (DBGCCL)
R/W
8
Debug Control Register 2 (DBGC2) / (BKPCT0)
R/W
9
Debug Control Register 3 (DBGC3) / (BKPCT1)
R/W
A
Debug Comparator A Extended Register (DBGCAX) / (/BKP0X)
R/W
B
Debug Comparator A Register High (DBGCAH) / (BKP0H)
R/W
Debug Comparator A Register Low (DBGCAL) / (BKP0L)
R/W
Debug Comparator B Extended Register (DBGCBX) / (BKP1X)
R/W
E
Debug Comparator B Register High (DBGCBH) / (BKP1H)
R/W
F
Debug Comparator B Register Low (DBGCBL) / (BKP1L)
R/W
Register Descriptions
This section consists of the DBG register descriptions in address order. Most of the register bits can be
written to in either BKP or DBG mode, although they may not have any effect in one of the modes.
However, the only bits in the DBG module that can be written while the debugger is armed (ARM = 1) are
DBGEN and ARM
Name1
DBGC1
DBGSC
R
W
R
Bit 7
6
5
4
3
DBGEN
ARM
TRGSEL
BEGIN
DBGBRK
AF
BF
CF
0
W
2
1
0
Bit 0
CAPMOD
TRG
= Unimplemented or Reserved
Figure 19-3. DBG Register Summary
MC9S12HZ256 Data Sheet, Rev. 2.04
540
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
Name1
DBGTBH
DBGTBL
DBGCNT
DBGCCX(2)
DBGCCH(2)
DBGCCL(2)
DBGC2
BKPCT0
DBGC3
BKPCT1
DBGCAX
BKP0X
DBGCAH
BKP0H
R
5
4
3
2
1
Bit 0
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
R
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
TBF
0
W
R
CNT
W
R
W
R
W
R
W
R
W
R
W
R
W
R
W
R
W
DBGCBX
BKP1X
W
DBGCBL
BKP1L
6
W
DBGCAL
BKP0L
DBGCBH
BKP1H
Bit 7
R
R
W
R
W
PAGSEL
EXTCMP
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
BKABEN
FULL
BDM
TAGAB
BKCEN
TAGC
RWCEN
RWC
BKAMBH
BKAMBL
BKBMBH
BKBMBL
RWAEN
RWA
RWBEN
RWB
PAGSEL
EXTCMP
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
PAGSEL
EXTCMP
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
= Unimplemented or Reserved
Figure 19-3. DBG Register Summary (continued)
1
The DBG module is designed for backwards compatibility to existing BKP modules. Register and bit names have changed from
the BKP module. This column shows the DBG register name, as well as the BKP register name for reference.
2 Comparator C can be used to enhance the BKP mode by providing a third breakpoint.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
541
Chapter 19 Debug Module (DBGV1)
19.3.2.1
Debug Control Register 1 (DBGC1)
NOTE
All bits are used in DBG mode only.
7
6
5
4
3
DBGEN
ARM
TRGSEL
BEGIN
DBGBRK
0
0
0
0
0
R
2
1
0
0
CAPMOD
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 19-4. Debug Control Register (DBGC1)
NOTE
This register cannot be written if BKP mode is enabled (BKABEN in
DBGC2 is set).
Table 19-3. DBGC1 Field Descriptions
Field
Description
7
DBGEN
DBG Mode Enable Bit — The DBGEN bit enables the DBG module for use in DBG mode. This bit cannot be
set if the MCU is in secure mode.
0 DBG mode disabled
1 DBG mode enabled
6
ARM
Arm Bit — The ARM bit controls whether the debugger is comparing and storing data in the trace buffer. See
Section 19.4.2.4, “Arming the DBG Module,” for more information.
0 Debugger unarmed
1 Debugger armed
Note: This bit cannot be set if the DBGEN bit is not also being set at the same time. For example, a write of 01
to DBGEN[7:6] will be interpreted as a write of 00.
5
TRGSEL
Trigger Selection Bit — The TRGSEL bit controls the triggering condition for comparators A and B in DBG
mode. It serves essentially the same function as the TAGAB bit in the DBGC2 register does in BKP mode. See
Section 19.4.2.1.2, “Trigger Selection,” for more information. TRGSEL may also determine the type of breakpoint
based on comparator A and B if enabled in DBG mode (DBGBRK = 1). Please refer to Section 19.4.3.1,
“Breakpoint Based on Comparator A and B.”
0 Trigger on any compare address match
1 Trigger before opcode at compare address gets executed (tagged-type)
4
BEGIN
Begin/End Trigger Bit — The BEGIN bit controls whether the trigger begins or ends storing of data in the trace
buffer. See Section 19.4.2.8.1, “Storing with Begin-Trigger,” and Section 19.4.2.8.2, “Storing with End-Trigger,”
for more details.
0 Trigger at end of stored data
1 Trigger before storing data
MC9S12HZ256 Data Sheet, Rev. 2.04
542
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
Table 19-3. DBGC1 Field Descriptions (continued)
Field
Description
3
DBGBRK
DBG Breakpoint Enable Bit — The DBGBRK bit controls whether the debugger will request a breakpoint based
on comparator A and B to the CPU upon completion of a tracing session. Please refer to Section 19.4.3,
“Breakpoints,” for further details.
0 CPU break request not enabled
1 CPU break request enabled
1:0
CAPMOD
Capture Mode Field — See Table 19-4 for capture mode field definitions. In LOOP1 mode, the debugger will
automatically inhibit redundant entries into capture memory. In detail mode, the debugger is storing address and
data for all cycles except program fetch (P) and free (f) cycles. In profile mode, the debugger is returning the
address of the last instruction executed by the CPU on each access of trace buffer address. Refer to
Section 19.4.2.6, “Capture Modes,” for more information.
Table 19-4. CAPMOD Encoding
CAPMOD
Description
00
Normal
01
LOOP1
10
DETAIL
11
PROFILE
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
543
Chapter 19 Debug Module (DBGV1)
19.3.2.2
R
Debug Status and Control Register (DBGSC)
7
6
5
4
AF
BF
CF
0
3
2
1
0
0
0
TRG
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 19-5. Debug Status and Control Register (DBGSC)
Table 19-5. DBGSC Field Descriptions
Field
Description
7
AF
Trigger A Match Flag — The AF bit indicates if trigger A match condition was met since arming. This bit is
cleared when ARM in DBGC1 is written to a 1 or on any write to this register.
0 Trigger A did not match
1 Trigger A match
6
BF
Trigger B Match Flag — The BF bit indicates if trigger B match condition was met since arming.This bit is
cleared when ARM in DBGC1 is written to a 1 or on any write to this register.
0 Trigger B did not match
1 Trigger B match
5
CF
Comparator C Match Flag — The CF bit indicates if comparator C match condition was met since arming.This
bit is cleared when ARM in DBGC1 is written to a 1 or on any write to this register.
0 Comparator C did not match
1 Comparator C match
3:0
TRG
Trigger Mode Bits — The TRG bits select the trigger mode of the DBG module as shown Table 19-6. See
Section 19.4.2.5, “Trigger Modes,” for more detail.
Table 19-6. Trigger Mode Encoding
TRG Value
Meaning
0000
A only
0001
A or B
0010
A then B
0011
Event only B
0100
A then event only B
0101
A and B (full mode)
0110
A and Not B (full mode)
0111
Inside range
1000
Outside range
1001
↓
1111
Reserved
(Defaults to A only)
MC9S12HZ256 Data Sheet, Rev. 2.04
544
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.3.2.3
R
Debug Trace Buffer Register (DBGTB)
15
14
13
12
11
10
9
8
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
u
u
u
u
u
u
u
u
W
Reset
= Unimplemented or Reserved
Figure 19-6. Debug Trace Buffer Register High (DBGTBH)
R
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
u
u
u
u
u
u
u
u
W
Reset
= Unimplemented or Reserved
Figure 19-7. Debug Trace Buffer Register Low (DBGTBL)
Table 19-7. DBGTB Field Descriptions
Field
Description
15:0
Trace Buffer Data Bits — The trace buffer data bits contain the data of the trace buffer. This register can be read
only as a word read. Any byte reads or misaligned access of these registers will return 0 and will not cause the
trace buffer pointer to increment to the next trace buffer address. The same is true for word reads while the
debugger is armed. In addition, this register may appear to contain incorrect data if it is not read with the same
capture mode bit settings as when the trace buffer data was recorded (See Section 19.4.2.9, “Reading Data from
Trace Buffer”). Because reads will reflect the contents of the trace buffer RAM, the reset state is undefined.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
545
Chapter 19 Debug Module (DBGV1)
19.3.2.4
R
Debug Count Register (DBGCNT)
7
6
TBF
0
0
0
5
4
3
2
1
0
0
0
0
CNT
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 19-8. Debug Count Register (DBGCNT)
Table 19-8. DBGCNT Field Descriptions
Field
Description
7
TBF
Trace Buffer Full — The TBF bit indicates that the trace buffer has stored 64 or more words of data since it was
last armed. If this bit is set, then all 64 words will be valid data, regardless of the value in CNT[5:0]. The TBF bit
is cleared when ARM in DBGC1 is written to a 1.
5:0
CNT
Count Value — The CNT bits indicate the number of valid data words stored in the trace buffer. Table 19-9 shows
the correlation between the CNT bits and the number of valid data words in the trace buffer. When the CNT rolls
over to 0, the TBF bit will be set and incrementing of CNT will continue if DBG is in end-trigger mode. The
DBGCNT register is cleared when ARM in DBGC1 is written to a 1.
Table 19-9. CNT Decoding Table
TBF
CNT
Description
0
000000
No data valid
0
000001
1 word valid
0
000010
..
..
111110
2 words valid
..
..
62 words valid
0
111111
63 words valid
1
000000
64 words valid; if BEGIN = 1, the
ARM bit will be cleared. A
breakpoint will be generated if
DBGBRK = 1
1
000001
..
..
111111
64 words valid,
oldest data has been overwritten
by most recent data
MC9S12HZ256 Data Sheet, Rev. 2.04
546
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.3.2.5
Debug Comparator C Extended Register (DBGCCX)
7
6
5
4
3
2
1
0
0
0
0
R
PAGSEL
EXTCMP
W
Reset
0
0
0
0
0
Figure 19-9. Debug Comparator C Extended Register (DBGCCX)
Table 19-10. DBGCCX Field Descriptions
Field
Description
7:6
PAGSEL
Page Selector Field — In both BKP and DBG mode, PAGSEL selects the type of paging as shown in
Table 19-11.
DPAGE and EPAGE are not yet implemented so the value in bit 7 will be ignored (i.e., PAGSEL values of 10 and
11 will be interpreted as values of 00 and 01, respectively).
5:0
EXTCMP
Comparator C Extended Compare Bits — The EXTCMP bits are used as comparison address bits as shown
in Table 19-11 along with the appropriate PPAGE, DPAGE, or EPAGE signal from the core.
Note: Comparator C can be used when the DBG module is configured for BKP mode. Extended addressing
comparisons for comparator C use PAGSEL and will operate differently to the way that comparator A and
B operate in BKP mode.
Table 19-11. PAGSEL Decoding1
PAGSEL
Description
EXTCMP
Comment
00
Normal (64k)
Not used
No paged memory
01
PPAGE
(256 — 16K pages)
EXTCMP[5:0] is compared to
address bits [21:16]2
PPAGE[7:0] / XAB[21:14] becomes
address bits [21:14]1
103
DPAGE (reserved)
(256 — 4K pages)
EXTCMP[3:0] is compared to
address bits [19:16]
DPAGE / XAB[21:14] becomes address
bits [19:12]
112
EPAGE (reserved)
(256 — 1K pages)
EXTCMP[1:0] is compared to
address bits [17:16]
EPAGE / XAB[21:14] becomes address
bits [17:10]
1
See Figure 19-10.
Current HCS12 implementations have PPAGE limited to 6 bits. Therefore, EXTCMP[5:4] should be set to 00.
3 Data page (DPAGE) and Extra page (EPAGE) are reserved for implementation on devices that support paged data and extra
space.
2
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
547
Chapter 19 Debug Module (DBGV1)
DBGCXX
7
DBGCXH[15:12]
EXTCMP
6
BIT 15
BIT 14
XAB16
XAB15
XAB14
PIX2
PIX1
PIX0
0
5
0
4
3
2
1
BIT 0
XAB21
XAB20
XAB19
XAB18
XAB17
PIX7
PIX6
PIX5
PIX4
PIX3
BIT 13
BIT 12
BKP/DBG MODE
PAGSEL
SEE NOTE 1
PORTK/XAB
PPAGE
SEE NOTE 2
NOTES:
1. In BKP and DBG mode, PAGSEL selects the type of paging as shown in Table 19-11.
2. Current HCS12 implementations are limited to six PPAGE bits, PIX[5:0]. Therefore, EXTCMP[5:4] = 00.
Figure 19-10. Comparator C Extended Comparison in BKP/DBG Mode
19.3.2.6
R
Debug Comparator C Register (DBGCC)
15
14
13
12
11
10
9
8
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 19-11. Debug Comparator C Register High (DBGCCH)
R
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 19-12. Debug Comparator C Register Low (DBGCCL)
Table 19-12. DBGCC Field Descriptions
Field
15:0
Description
Comparator C Compare Bits — The comparator C compare bits control whether comparator C will compare
the address bus bits [15:0] to a logic 1 or logic 0. See Table 19-13.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
Note: This register will be cleared automatically when the DBG module is armed in LOOP1 mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
548
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
Table 19-13. Comparator C Compares
PAGSEL
EXTCMP Compare
High-Byte Compare
x0
No compare
DBGCCH[7:0] = AB[15:8]
x1
EXTCMP[5:0] = XAB[21:16]
DBGCCH[7:0] = XAB[15:14],AB[13:8]
19.3.2.7
R
Debug Control Register 2 (DBGC2)
7
6
5
4
3
2
1
0
BKABEN1
FULL
BDM
TAGAB
BKCEN2
TAGC2
RWCEN2
RWC2
0
0
0
0
0
0
0
0
W
Reset
1
When BKABEN is set (BKP mode), all bits in DBGC2 are available. When BKABEN is cleared and DBG is used in DBG mode,
bits FULL and TAGAB have no meaning.
2 These bits can be used in BKP mode and DBG mode (when capture mode is not set in LOOP1) to provide a third breakpoint.
Figure 19-13. Debug Control Register 2 (DBGC2)
Table 19-14. DBGC2 Field Descriptions
Field
Description
7
BKABEN
Breakpoint Using Comparator A and B Enable — This bit enables the breakpoint capability using comparator
A and B, when set (BKP mode) the DBGEN bit in DBGC1 cannot be set.
0 Breakpoint module off
1 Breakpoint module on
6
FULL
Full Breakpoint Mode Enable — This bit controls whether the breakpoint module is in dual mode or full mode.
In full mode, comparator A is used to match address and comparator B is used to match data. See
Section 19.4.1.2, “Full Breakpoint Mode,” for more details.
0 Dual address mode enabled
1 Full breakpoint mode enabled
5
BDM
Background Debug Mode Enable — This bit determines if the breakpoint causes the system to enter
background debug mode (BDM) or initiate a software interrupt (SWI).
0 Go to software interrupt on a break request
1 Go to BDM on a break request
4
TAGAB
Comparator A/B Tag Select — This bit controls whether the breakpoint will cause a break on the next instruction
boundary (force) or on a match that will be an executable opcode (tagged). Non-executed opcodes cannot cause
a tagged breakpoint.
0 On match, break at the next instruction boundary (force)
1 On match, break if/when the instruction is about to be executed (tagged)
3
BKCEN
Breakpoint Comparator C Enable Bit — This bit enables the breakpoint capability using comparator C.
0 Comparator C disabled for breakpoint
1 Comparator C enabled for breakpoint
Note: This bit will be cleared automatically when the DBG module is armed in loop1 mode.
2
TAGC
Comparator C Tag Select — This bit controls whether the breakpoint will cause a break on the next instruction
boundary (force) or on a match that will be an executable opcode (tagged). Non-executed opcodes cannot cause
a tagged breakpoint.
0 On match, break at the next instruction boundary (force)
1 On match, break if/when the instruction is about to be executed (tagged)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
549
Chapter 19 Debug Module (DBGV1)
Table 19-14. DBGC2 Field Descriptions (continued)
Field
Description
1
RWCEN
Read/Write Comparator C Enable Bit — The RWCEN bit controls whether read or write comparison is enabled
for comparator C. RWCEN is not useful for tagged breakpoints.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
0
RWC
19.3.2.8
R
Read/Write Comparator C Value Bit — The RWC bit controls whether read or write is used in compare for
comparator C. The RWC bit is not used if RWCEN = 0.
0 Write cycle will be matched
1 Read cycle will be matched
Debug Control Register 3 (DBGC3)
7
6
5
4
3
2
1
0
BKAMBH1
BKAMBL1
BKBMBH2
BKBMBL2
RWAEN
RWA
RWBEN
RWB
0
0
0
0
0
0
0
0
W
Reset
1
2
In DBG mode, BKAMBH:BKAMBL has no meaning and are forced to 0’s.
In DBG mode, BKBMBH:BKBMBL are used in full mode to qualify data.
Figure 19-14. Debug Control Register 3 (DBGC3)
Table 19-15. DBGC3 Field Descriptions
Field
Description
7:6
Breakpoint Mask High Byte for First Address — In dual or full mode, these bits may be used to mask (disable)
BKAMB[H:L] the comparison of the high and/or low bytes of the first address breakpoint. The functionality is as given in
Table 19-16.
The x:0 case is for a full address compare. When a program page is selected, the full address compare will be
based on bits for a 20-bit compare. The registers used for the compare are {DBGCAX[5:0], DBGCAH[5:0],
DBGCAL[7:0]}, where DBGAX[5:0] corresponds to PPAGE[5:0] or extended address bits [19:14] and CPU
address [13:0]. When a program page is not selected, the full address compare will be based on bits for a 16-bit
compare. The registers used for the compare are {DBGCAH[7:0], DBGCAL[7:0]} which corresponds to CPU
address [15:0].
Note: This extended address compare scheme causes an aliasing problem in BKP mode in which several
physical addresses may match with a single logical address. This problem may be avoided by using DBG
mode to generate breakpoints.
The 1:0 case is not sensible because it would ignore the high order address and compare the low order and
expansion addresses. Logic forces this case to compare all address lines (effectively ignoring the BKAMBH
control bit).
The 1:1 case is useful for triggering a breakpoint on any access to a particular expansion page. This only makes
sense if a program page is being accessed so that the breakpoint trigger will occur only if DBGCAX compares.
MC9S12HZ256 Data Sheet, Rev. 2.04
550
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
Table 19-15. DBGC3 Field Descriptions (continued)
Field
Description
5:4
Breakpoint Mask High Byte and Low Byte of Data (Second Address) — In dual mode, these bits may be
BKBMB[H:L] used to mask (disable) the comparison of the high and/or low bytes of the second address breakpoint. The
functionality is as given in Table 19-17.
The x:0 case is for a full address compare. When a program page is selected, the full address compare will be
based on bits for a 20-bit compare. The registers used for the compare are {DBGCBX[5:0], DBGCBH[5:0],
DBGCBL[7:0]} where DBGCBX[5:0] corresponds to PPAGE[5:0] or extended address bits [19:14] and CPU
address [13:0]. When a program page is not selected, the full address compare will be based on bits for a 16-bit
compare. The registers used for the compare are {DBGCBH[7:0], DBGCBL[7:0]} which corresponds to CPU
address [15:0].
Note: This extended address compare scheme causes an aliasing problem in BKP mode in which several
physical addresses may match with a single logical address. This problem may be avoided by using DBG
mode to generate breakpoints.
The 1:0 case is not sensible because it would ignore the high order address and compare the low order and
expansion addresses. Logic forces this case to compare all address lines (effectively ignoring the BKBMBH
control bit).
The 1:1 case is useful for triggering a breakpoint on any access to a particular expansion page. This only makes
sense if a program page is being accessed so that the breakpoint trigger will occur only if DBGCBX compares.
In full mode, these bits may be used to mask (disable) the comparison of the high and/or low bytes of the data
breakpoint. The functionality is as given in Table 19-18.
3
RWAEN
2
RWA
Read/Write Comparator A Value Bit — The RWA bit controls whether read or write is used in compare for
comparator A. The RWA bit is not used if RWAEN = 0.
0 Write cycle will be matched
1 Read cycle will be matched
1
RWBEN
0
RWB
Read/Write Comparator A Enable Bit — The RWAEN bit controls whether read or write comparison is enabled
for comparator A. See Section 19.4.2.1.1, “Read or Write Comparison,” for more information. This bit is not useful
for tagged operations.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
Read/Write Comparator B Enable Bit — The RWBEN bit controls whether read or write comparison is enabled
for comparator B. See Section 19.4.2.1.1, “Read or Write Comparison,” for more information. This bit is not useful
for tagged operations.
0 Read/Write is not used in comparison
1 Read/Write is used in comparison
Read/Write Comparator B Value Bit — The RWB bit controls whether read or write is used in compare for
comparator B. The RWB bit is not used if RWBEN = 0.
0 Write cycle will be matched
1 Read cycle will be matched
Note: RWB and RWBEN are not used in full mode.
Table 19-16. Breakpoint Mask Bits for First Address
BKAMBH:BKAMBL
Address Compare
DBGCAX
DBGCAH
DBGCAL
x:0
Full address compare
Yes1
Yes
Yes
256 byte address range
Yes1
Yes
No
16K byte address range
1
No
No
0:1
1:1
1
Yes
If PPAGE is selected.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
551
Chapter 19 Debug Module (DBGV1)
Table 19-17. Breakpoint Mask Bits for Second Address (Dual Mode)
BKBMBH:BKBMBL
DBGCBH
DBGCBL
Full address compare
Yes
1
Yes
Yes
0:1
256 byte address range
Yes1
Yes
No
1:1
16K byte address range
Yes1
No
No
x:0
1
Address Compare
DBGCBX
If PPAGE is selected.
Table 19-18. Breakpoint Mask Bits for Data Breakpoints (Full Mode)
BKBMBH:BKBMBL
0:0
1
Data Compare
High and low byte compare
DBGCBX
DBGCBH
DBGCBL
1
Yes
Yes
1
No
0:1
High byte
No
Yes
No
1:0
Low byte
No1
No
Yes
1:1
No compare
No1
No
No
Expansion addresses for breakpoint B are not applicable in this mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
552
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.3.2.9
Debug Comparator A Extended Register (DBGCAX)
7
6
5
4
3
2
1
0
0
0
0
R
PAGSEL
EXTCMP
W
Reset
0
0
0
0
0
Figure 19-15. Debug Comparator A Extended Register (DBGCAX)
Table 19-19. DBGCAX Field Descriptions
Field
7:6
PAGSEL
Description
Page Selector Field — If DBGEN is set in DBGC1, then PAGSEL selects the type of paging as shown in
Table 19-20.
DPAGE and EPAGE are not yet implemented so the value in bit 7 will be ignored (i.e., PAGSEL values of 10 and
11 will be interpreted as values of 00 and 01, respectively).
In BKP mode, PAGSEL has no meaning and EXTCMP[5:0] are compared to address bits [19:14] if the address
is in the FLASH/ROM memory space.
5:0
EXTCMP
Comparator A Extended Compare Bits — The EXTCMP bits are used as comparison address bits as shown
in Table 19-20 along with the appropriate PPAGE, DPAGE, or EPAGE signal from the core.
Table 19-20. Comparator A or B Compares
Mode
BKP
1
DBG2
2
High-Byte Compare
Not FLASH/ROM access
No compare
DBGCxH[7:0] = AB[15:8]
FLASH/ROM access
EXTCMP[5:0] = XAB[19:14]
DBGCxH[5:0] = AB[13:8]
PAGSEL = 00
No compare
DBGCxH[7:0] = AB[15:8]
PAGSEL = 01
EXTCMP[5:0] = XAB[21:16]
DBGCxH[7:0] = XAB[15:14], AB[13:8]
See Figure 19-16.
See Figure 19-10 (note that while this figure provides extended comparisons for comparator C, the figure also pertains to
comparators A and B in DBG mode only).
PAGSEL
DBGCXX
0
EXTCMP
0
5
4
3
2
1
BIT 0
SEE NOTE 1
PORTK/XAB
PPAGE
XAB21
XAB20
XAB19
XAB18
XAB17
XAB16
XAB15
XAB14
PIX7
PIX6
PIX5
PIX4
PIX3
PIX2
PIX1
PIX0
BKP MODE
1
EXTCMP Compare
SEE NOTE 2
NOTES:
1. In BKP mode, PAGSEL has no functionality. Therefore, set PAGSEL to 00 (reset state).
2. Current HCS12 implementations are limited to six PPAGE bits, PIX[5:0].
Figure 19-16. Comparators A and B Extended Comparison in BKP Mode
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
553
Chapter 19 Debug Module (DBGV1)
19.3.2.10 Debug Comparator A Register (DBGCA)
15
14
13
12
11
10
9
8
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 19-17. Debug Comparator A Register High (DBGCAH)
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 19-18. Debug Comparator A Register Low (DBGCAL)
Table 19-21. DBGCA Field Descriptions
Field
Description
15:0
15:0
Comparator A Compare Bits — The comparator A compare bits control whether comparator A compares the
address bus bits [15:0] to a logic 1 or logic 0. See Table 19-20.
0 Compare corresponding address bit to a logic 0
1 Compare corresponding address bit to a logic 1
19.3.2.11 Debug Comparator B Extended Register (DBGCBX)
7
6
5
4
3
2
1
0
0
0
0
R
PAGSEL
EXTCMP
W
Reset
0
0
0
0
0
Figure 19-19. Debug Comparator B Extended Register (DBGCBX)
Table 19-22. DBGCBX Field Descriptions
Field
7:6
PAGSEL
Description
Page Selector Field — If DBGEN is set in DBGC1, then PAGSEL selects the type of paging as shown in
Table 19-11.
DPAGE and EPAGE are not yet implemented so the value in bit 7 will be ignored (i.e., PAGSEL values of 10 and
11 will be interpreted as values of 00 and 01, respectively.)
In BKP mode, PAGSEL has no meaning and EXTCMP[5:0] are compared to address bits [19:14] if the address
is in the FLASH/ROM memory space.
5:0
EXTCMP
Comparator B Extended Compare Bits — The EXTCMP bits are used as comparison address bits as shown
in Table 19-11 along with the appropriate PPAGE, DPAGE, or EPAGE signal from the core. Also see Table 19-20.
MC9S12HZ256 Data Sheet, Rev. 2.04
554
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.3.2.12 Debug Comparator B Register (DBGCB)
15
14
13
12
11
10
9
8
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 19-20. Debug Comparator B Register High (DBGCBH)
7
6
5
4
3
2
1
0
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 19-21. Debug Comparator B Register Low (DBGCBL)
Table 19-23. DBGCB Field Descriptions
Field
Description
15:0
15:0
Comparator B Compare Bits — The comparator B compare bits control whether comparator B compares the
address bus bits [15:0] or data bus bits [15:0] to a logic 1 or logic 0. See Table 19-20.
0 Compare corresponding address bit to a logic 0, compares to data if in Full mode
1 Compare corresponding address bit to a logic 1, compares to data if in Full mode
19.4
Functional Description
This section provides a complete functional description of the DBG module. The DBG module can be
configured to run in either of two modes, BKP or DBG. BKP mode is enabled by setting BKABEN in
DBGC2. DBG mode is enabled by setting DBGEN in DBGC1. Setting BKABEN in DBGC2 overrides the
DBGEN in DBGC1 and prevents DBG mode. If the part is in secure mode, DBG mode cannot be enabled.
19.4.1
DBG Operating in BKP Mode
In BKP mode, the DBG will be fully backwards compatible with the existing BKP_ST12_A module. The
DBGC2 register has four additional bits that were not available on existing BKP_ST12_A modules. As
long as these bits are written to either all 1s or all 0s, they should be transparent to the user. All 1s would
enable comparator C to be used as a breakpoint, but tagging would be enabled. The match address register
would be all 0s if not modified by the user. Therefore, code executing at address 0x0000 would have to
occur before a breakpoint based on comparator C would happen.
The DBG module in BKP mode supports two modes of operation: dual address mode and full breakpoint
mode. Within each of these modes, forced or tagged breakpoint types can be used. Forced breakpoints
occur at the next instruction boundary if a match occurs and tagged breakpoints allow for breaking just
before the tagged instruction executes. The action taken upon a successful match can be to either place the
CPU in background debug mode or to initiate a software interrupt.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
555
Chapter 19 Debug Module (DBGV1)
The breakpoint can operate in dual address mode or full breakpoint mode. Each of these modes is
discussed in the subsections below.
19.4.1.1
Dual Address Mode
When dual address mode is enabled, two address breakpoints can be set. Each breakpoint can cause the
system to enter background debug mode or to initiate a software interrupt based upon the state of BDM in
DBGC2 being logic 1 or logic 0, respectively. BDM requests have a higher priority than SWI requests. No
data breakpoints are allowed in this mode.
TAGAB in DBGC2 selects whether the breakpoint mode is forced or tagged. The BKxMBH:L bits in
DBGC3 select whether or not the breakpoint is matched exactly or is a range breakpoint. They also select
whether the address is matched on the high byte, low byte, both bytes, and/or memory expansion. The
RWx and RWxEN bits in DBGC3 select whether the type of bus cycle to match is a read, write, or
read/write when performing forced breakpoints.
19.4.1.2
Full Breakpoint Mode
Full breakpoint mode requires a match on address and data for a breakpoint to occur. Upon a successful
match, the system will enter background debug mode or initiate a software interrupt based upon the state
of BDM in DBGC2 being logic 1 or logic 0, respectively. BDM requests have a higher priority than SWI
requests. R/W matches are also allowed in this mode.
TAGAB in DBGC2 selects whether the breakpoint mode is forced or tagged. When TAGAB is set in
DBGC2, only addresses are compared and data is ignored. The BKAMBH:L bits in DBGC3 select
whether or not the breakpoint is matched exactly, is a range breakpoint, or is in page space. The
BKBMBH:L bits in DBGC3 select whether the data is matched on the high byte, low byte, or both bytes.
RWA and RWAEN bits in DBGC2 select whether the type of bus cycle to match is a read or a write when
performing forced breakpoints. RWB and RWBEN bits in DBGC2 are not used in full breakpoint mode.
NOTE
The full trigger mode is designed to be used for either a word access or a
byte access, but not both at the same time. Confusing trigger operation
(seemingly false triggers or no trigger) can occur if the trigger address
occurs in the user program as both byte and word accesses.
19.4.1.3
Breakpoint Priority
Breakpoint operation is first determined by the state of the BDM module. If the BDM module is already
active, meaning the CPU is executing out of BDM firmware, breakpoints are not allowed. In addition,
while executing a BDM TRACE command, tagging into BDM is not allowed. If BDM is not active, the
breakpoint will give priority to BDM requests over SWI requests. This condition applies to both forced
and tagged breakpoints.
In all cases, BDM related breakpoints will have priority over those generated by the Breakpoint sub-block.
This priority includes breakpoints enabled by the TAGLO and TAGHI external pins of the system that
interface with the BDM directly and whose signal information passes through and is used by the
breakpoint sub-block.
MC9S12HZ256 Data Sheet, Rev. 2.04
556
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
NOTE
BDM should not be entered from a breakpoint unless the ENABLE bit is set
in the BDM. Even if the ENABLE bit in the BDM is cleared, the CPU
actually executes the BDM firmware code. It checks the ENABLE and
returns if ENABLE is not set. If the BDM is not serviced by the monitor then
the breakpoint would be re-asserted when the BDM returns to normal CPU
flow.
There is no hardware to enforce restriction of breakpoint operation if the
BDM is not enabled.
When program control returns from a tagged breakpoint through an RTI or
a BDM GO command, it will return to the instruction whose tag generated
the breakpoint. Unless breakpoints are disabled or modified in the service
routine or active BDM session, the instruction will be tagged again and the
breakpoint will be repeated. In the case of BDM breakpoints, this situation
can also be avoided by executing a TRACE1 command before the GO to
increment the program flow past the tagged instruction.
19.4.1.4
Using Comparator C in BKP Mode
The original BKP_ST12_A module supports two breakpoints. The DBG_ST12_A module can be used in
BKP mode and allow a third breakpoint using comparator C. Four additional bits, BKCEN, TAGC,
RWCEN, and RWC in DBGC2 in conjunction with additional comparator C address registers, DBGCCX,
DBGCCH, and DBGCCL allow the user to set up a third breakpoint. Using PAGSEL in DBGCCX for
expanded memory will work differently than the way paged memory is done using comparator A and B in
BKP mode. See Section 19.3.2.5, “Debug Comparator C Extended Register (DBGCCX),” for more
information on using comparator C.
19.4.2
DBG Operating in DBG Mode
Enabling the DBG module in DBG mode, allows the arming, triggering, and storing of data in the trace
buffer and can be used to cause CPU breakpoints. The DBG module is made up of three main blocks, the
comparators, trace buffer control logic, and the trace buffer.
NOTE
In general, there is a latency between the triggering event appearing on the
bus and being detected by the DBG circuitry. In general, tagged triggers will
be more predictable than forced triggers.
19.4.2.1
Comparators
The DBG contains three comparators, A, B, and C. Comparator A compares the core address bus with the
address stored in DBGCAH and DBGCAL. Comparator B compares the core address bus with the address
stored in DBGCBH and DBGCBL except in full mode, where it compares the data buses to the data stored
in DBGCBH and DBGCBL. Comparator C can be used as a breakpoint generator or as the address
comparison unit in the loop1 mode. Matches on comparator A, B, and C are signaled to the trace buffer
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
557
Chapter 19 Debug Module (DBGV1)
control (TBC) block. When PAGSEL = 01, registers DBGCAX, DBGCBX, and DBGCCX are used to
match the upper addresses as shown in Table 19-11.
NOTE
If a tagged-type C breakpoint is set at the same address as an A/B
tagged-type trigger (including the initial entry in an inside or outside range
trigger), the C breakpoint will have priority and the trigger will not be
recognized.
19.4.2.1.1
Read or Write Comparison
Read or write comparisons are useful only with TRGSEL = 0, because only opcodes should be tagged as
they are “read” from memory. RWAEN and RWBEN are ignored when TRGSEL = 1.
In full modes (“A and B” and “A and not B”) RWAEN and RWA are used to select read or write
comparisons for both comparators A and B. Table 19-24 shows the effect for RWAEN, RWA, and RW on
the DBGCB comparison conditions. The RWBEN and RWB bits are not used and are ignored in full
modes.
Table 19-24. Read or Write Comparison Logic Table
19.4.2.1.2
RWAEN bit
RWA bit
RW signal
Comment
0
x
0
Write data bus
0
x
1
Read data bus
1
0
0
Write data bus
1
0
1
No data bus compare since RW=1
1
1
0
No data bus compare since RW=0
1
1
1
Read data bus
Trigger Selection
The TRGSEL bit in DBGC1 is used to determine the triggering condition in DBG mode. TRGSEL applies
to both trigger A and B except in the event only trigger modes. By setting TRGSEL, the comparators A
and B will qualify a match with the output of opcode tracking logic and a trigger occurs before the tagged
instruction executes (tagged-type trigger). With the TRGSEL bit cleared, a comparator match forces a
trigger when the matching condition occurs (force-type trigger).
NOTE
If the TRGSEL is set, the address stored in the comparator match address
registers must be an opcode address for the trigger to occur.
19.4.2.2
Trace Buffer Control (TBC)
The TBC is the main controller for the DBG module. Its function is to decide whether data should be stored
in the trace buffer based on the trigger mode and the match signals from the comparator. The TBC also
determines whether a request to break the CPU should occur.
MC9S12HZ256 Data Sheet, Rev. 2.04
558
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.4.2.3
Begin- and End-Trigger
The definitions of begin- and end-trigger as used in the DBG module are as follows:
• Begin-trigger: Storage in trace buffer occurs after the trigger and continues until 64 locations are
filled.
• End-trigger: Storage in trace buffer occurs until the trigger, with the least recent data falling out of
the trace buffer if more than 64 words are collected.
19.4.2.4
Arming the DBG Module
In DBG mode, arming occurs by setting DBGEN and ARM in DBGC1. The ARM bit in DBGC1 is cleared
when the trigger condition is met in end-trigger mode or when the Trace Buffer is filled in begin-trigger
mode. The TBC logic determines whether a trigger condition has been met based on the trigger mode and
the trigger selection.
19.4.2.5
Trigger Modes
The DBG module supports nine trigger modes. The trigger modes are encoded as shown in Table 19-6.
The trigger mode is used as a qualifier for either starting or ending the storing of data in the trace buffer.
When the match condition is met, the appropriate flag A or B is set in DBGSC. Arming the DBG module
clears the A, B, and C flags in DBGSC. In all trigger modes except for the event-only modes and DETAIL
capture mode, change-of-flow addresses are stored in the trace buffer. In the event-only modes only the
value on the data bus at the trigger event B will be stored. In DETAIL capture mode address and data for
all cycles except program fetch (P) and free (f) cycles are stored in trace buffer.
19.4.2.5.1
A Only
In the A only trigger mode, if the match condition for A is met, the A flag in DBGSC is set and a trigger
occurs.
19.4.2.5.2
A or B
In the A or B trigger mode, if the match condition for A or B is met, the corresponding flag in DBGSC is
set and a trigger occurs.
19.4.2.5.3
A then B
In the A then B trigger mode, the match condition for A must be met before the match condition for B is
compared. When the match condition for A or B is met, the corresponding flag in DBGSC is set. The
trigger occurs only after A then B have matched.
NOTE
When tagging and using A then B, if addresses A and B are close together,
then B may not complete the trigger sequence. This occurs when A and B
are in the instruction queue at the same time. Basically the A trigger has not
yet occurred, so the B instruction is not tagged. Generally, if address B is at
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
559
Chapter 19 Debug Module (DBGV1)
least six addresses higher than address A (or B is lower than A) and there
are not changes of flow to put these in the queue at the same time, then this
operation should trigger properly.
19.4.2.5.4
Event-Only B (Store Data)
In the event-only B trigger mode, if the match condition for B is met, the B flag in DBGSC is set and a
trigger occurs. The event-only B trigger mode is considered a begin-trigger type and the BEGIN bit in
DBGC1 is ignored. Event-only B is incompatible with instruction tagging (TRGSEL = 1), and thus the
value of TRGSEL is ignored. Please refer to Section 19.4.2.7, “Storage Memory,” for more information.
This trigger mode is incompatible with the detail capture mode so the detail capture mode will have
priority. TRGSEL and BEGIN will not be ignored and this trigger mode will behave as if it were “B only”.
19.4.2.5.5
A then Event-Only B (Store Data)
In the A then event-only B trigger mode, the match condition for A must be met before the match condition
for B is compared, after the A match has occurred, a trigger occurs each time B matches. When the match
condition for A or B is met, the corresponding flag in DBGSC is set. The A then event-only B trigger mode
is considered a begin-trigger type and BEGIN in DBGC1 is ignored. TRGSEL in DBGC1 applies only to
the match condition for A. Please refer to Section 19.4.2.7, “Storage Memory,” for more information.
This trigger mode is incompatible with the detail capture mode so the detail capture mode will have
priority. TRGSEL and BEGIN will not be ignored and this trigger mode will be the same as A then B.
19.4.2.5.6
A and B (Full Mode)
In the A and B trigger mode, comparator A compares to the address bus and comparator B compares to
the data bus. In the A and B trigger mode, if the match condition for A and B happen on the same bus cycle,
both the A and B flags in the DBGSC register are set and a trigger occurs.
If TRGSEL = 1, only matches from comparator A are used to determine if the trigger condition is met and
comparator B matches are ignored. If TRGSEL = 0, full-word data matches on an odd address boundary
(misaligned access) do not work unless the access is to a RAM that manages misaligned accesses in a
single clock cycle (which is typical of RAM modules used in HCS12 MCUs).
19.4.2.5.7
A and Not B (Full Mode)
In the A and not B trigger mode, comparator A compares to the address bus and comparator B compares
to the data bus. In the A and not B trigger mode, if the match condition for A and not B happen on the same
bus cycle, both the A and B flags in DBGSC are set and a trigger occurs.
If TRGSEL = 1, only matches from comparator A are used to determine if the trigger condition is met and
comparator B matches are ignored. As described in Section 19.4.2.5.6, “A and B (Full Mode),” full-word
data compares on misaligned accesses will not match expected data (and thus will cause a trigger in this
mode) unless the access is to a RAM that manages misaligned accesses in a single clock cycle.
MC9S12HZ256 Data Sheet, Rev. 2.04
560
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.4.2.5.8
Inside Range (A ≤ address ≤ B)
In the inside range trigger mode, if the match condition for A and B happen on the same bus cycle, both
the A and B flags in DBGSC are set and a trigger occurs. If a match condition on only A or only B occurs
no flags are set. If TRGSEL = 1, the inside range is accurate only to word boundaries. If TRGSEL = 0, an
aligned word access which straddles the range boundary will cause a trigger only if the aligned address is
within the range.
19.4.2.5.9
Outside Range (address < A or address > B)
In the outside range trigger mode, if the match condition for A or B is met, the corresponding flag in
DBGSC is set and a trigger occurs. If TRGSEL = 1, the outside range is accurate only to word boundaries.
If TRGSEL = 0, an aligned word access which straddles the range boundary will cause a trigger only if the
aligned address is outside the range.
19.4.2.5.10 Control Bit Priorities
The definitions of some of the control bits are incompatible with each other. Table 19-25 and the notes
associated with it summarize how these incompatibilities are managed:
• Read/write comparisons are not compatible with TRGSEL = 1. Therefore, RWAEN and RWBEN
are ignored.
• Event-only trigger modes are always considered a begin-type trigger. See Section 19.4.2.8.1,
“Storing with Begin-Trigger,” and Section 19.4.2.8.2, “Storing with End-Trigger.”
• Detail capture mode has priority over the event-only trigger/capture modes. Therefore, event-only
modes have no meaning in detail mode and their functions default to similar trigger modes.
Table 19-25. Resolution of Mode Conflicts
Normal / Loop1
Detail
Mode
Tag
Force
Tag
Force
A only
A or B
A then B
Event-only B
1
1, 3
3
A then event-only B
2
4
4
A and B (full mode)
5
5
A and not B (full mode)
5
5
Inside range
6
6
Outside range
6
6
1 — Ignored — same as force
2 — Ignored for comparator B
3 — Reduces to effectively “B only”
4 — Works same as A then B
5 — Reduces to effectively “A only” — B not compared
6 — Only accurate to word boundaries
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
561
Chapter 19 Debug Module (DBGV1)
19.4.2.6
Capture Modes
The DBG in DBG mode can operate in four capture modes. These modes are described in the following
subsections.
19.4.2.6.1
Normal Mode
In normal mode, the DBG module uses comparator A and B as triggering devices. Change-of-flow
information or data will be stored depending on TRG in DBGSC.
19.4.2.6.2
Loop1 Mode
The intent of loop1 mode is to prevent the trace buffer from being filled entirely with duplicate information
from a looping construct such as delays using the DBNE instruction or polling loops using
BRSET/BRCLR instructions. Immediately after address information is placed in the trace buffer, the DBG
module writes this value into the C comparator and the C comparator is placed in ignore address mode.
This will prevent duplicate address entries in the trace buffer resulting from repeated bit-conditional
branches. Comparator C will be cleared when the ARM bit is set in loop1 mode to prevent the previous
contents of the register from interfering with loop1 mode operation. Breakpoints based on comparator C
are disabled.
Loop1 mode only inhibits duplicate source address entries that would typically be stored in most tight
looping constructs. It will not inhibit repeated entries of destination addresses or vector addresses, because
repeated entries of these would most likely indicate a bug in the user’s code that the DBG module is
designed to help find.
NOTE
In certain very tight loops, the source address will have already been fetched
again before the C comparator is updated. This results in the source address
being stored twice before further duplicate entries are suppressed. This
condition occurs with branch-on-bit instructions when the branch is fetched
by the first P-cycle of the branch or with loop-construct instructions in
which the branch is fetched with the first or second P cycle. See examples
below:
LOOP
INCX
; 1-byte instruction fetched by 1st P-cycle of BRCLR
BRCLR CMPTMP,#$0c,LOOP ; the BRCLR instruction also will be fetched by 1st P-cycle of BRCLR
LOOP2 BRN
NOP
DBNE
*
A,LOOP2
; 2-byte instruction fetched by 1st P-cycle of DBNE
; 1-byte instruction fetched by 2nd P-cycle of DBNE
; this instruction also fetched by 2nd P-cycle of DBNE
NOTE
Loop1 mode does not support paged memory, and inhibits duplicate entries
in the trace buffer based solely on the CPU address. There is a remote
possibility of an erroneous address match if program flow alternates
between paged and unpaged memory space.
MC9S12HZ256 Data Sheet, Rev. 2.04
562
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
19.4.2.6.3
Detail Mode
In the detail mode, address and data for all cycles except program fetch (P) and free (f) cycles are stored
in trace buffer. This mode is intended to supply additional information on indexed, indirect addressing
modes where storing only the destination address would not provide all information required for a user to
determine where his code was in error.
19.4.2.6.4
Profile Mode
This mode is intended to allow a host computer to poll a running target and provide a histogram of program
execution. Each read of the trace buffer address will return the address of the last instruction executed. The
DBGCNT register is not incremented and the trace buffer does not get filled. The ARM bit is not used and
all breakpoints and all other debug functions will be disabled.
19.4.2.7
Storage Memory
The storage memory is a 64 words deep by 16-bits wide dual port RAM array. The CPU accesses the RAM
array through a single memory location window (DBGTBH:DBGTBL). The DBG module stores trace
information in the RAM array in a circular buffer format. As data is read via the CPU, a pointer into the
RAM will increment so that the next CPU read will receive fresh information. In all trigger modes except
for event-only and detail capture mode, the data stored in the trace buffer will be change-of-flow addresses.
change-of-flow addresses are defined as follows:
• Source address of conditional branches (long, short, BRSET, and loop constructs) taken
• Destination address of indexed JMP, JSR, and CALL instruction
• Destination address of RTI, RTS, and RTC instructions
• Vector address of interrupts except for SWI and BDM vectors
In the event-only trigger modes only the 16-bit data bus value corresponding to the event is stored. In the
detail capture mode, address and then data are stored for all cycles except program fetch (P) and free (f)
cycles.
19.4.2.8
19.4.2.8.1
Storing Data in Memory Storage Buffer
Storing with Begin-Trigger
Storing with begin-trigger can be used in all trigger modes. When DBG mode is enabled and armed in the
begin-trigger mode, data is not stored in the trace buffer until the trigger condition is met. As soon as the
trigger condition is met, the DBG module will remain armed until 64 words are stored in the trace buffer.
If the trigger is at the address of the change-of-flow instruction the change-of-flow associated with the
trigger event will be stored in the trace buffer.
19.4.2.8.2
Storing with End-Trigger
Storing with end-trigger cannot be used in event-only trigger modes. When DBG mode is enabled and
armed in the end-trigger mode, data is stored in the trace buffer until the trigger condition is met. When
the trigger condition is met, the DBG module will become de-armed and no more data will be stored. If
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
563
Chapter 19 Debug Module (DBGV1)
the trigger is at the address of a change-of-flow address the trigger event will not be stored in the trace
buffer.
19.4.2.9
Reading Data from Trace Buffer
The data stored in the trace buffer can be read using either the background debug module (BDM) module
or the CPU provided the DBG module is enabled and not armed. The trace buffer data is read out first-in
first-out. By reading CNT in DBGCNT the number of valid words can be determined. CNT will not
decrement as data is read from DBGTBH:DBGTBL. The trace buffer data is read by reading
DBGTBH:DBGTBL with a 16-bit read. Each time DBGTBH:DBGTBL is read, a pointer in the DBG will
be incremented to allow reading of the next word.
Reading the trace buffer while the DBG module is armed will return invalid data and no shifting of the
RAM pointer will occur.
NOTE
The trace buffer should be read with the DBG module enabled and in the
same capture mode that the data was recorded. The contents of the trace
buffer counter register (DBGCNT) are resolved differently in detail mode
verses the other modes and may lead to incorrect interpretation of the trace
buffer data.
19.4.3
Breakpoints
There are two ways of getting a breakpoint in DBG mode. One is based on the trigger condition of the
trigger mode using comparator A and/or B, and the other is using comparator C. External breakpoints
generated using the TAGHI and TAGLO external pins are disabled in DBG mode.
19.4.3.1
Breakpoint Based on Comparator A and B
A breakpoint request to the CPU can be enabled by setting DBGBRK in DBGC1. The value of BEGIN in
DBGC1 determines when the breakpoint request to the CPU will occur. When BEGIN in DBGC1 is set,
begin-trigger is selected and the breakpoint request will not occur until the trace buffer is filled with
64 words. When BEGIN in DBGC1 is cleared, end-trigger is selected and the breakpoint request will occur
immediately at the trigger cycle.
There are two types of breakpoint requests supported by the DBG module, tagged and forced. Tagged
breakpoints are associated with opcode addresses and allow breaking just before a specific instruction
executes. Forced breakpoints are not associated with opcode addresses and allow breaking at the next
instruction boundary. The type of breakpoint based on comparators A and B is determined by TRGSEL in
the DBGC1 register (TRGSEL = 1 for tagged breakpoint, TRGSEL = 0 for forced breakpoint).
Table 19-26 illustrates the type of breakpoint that will occur based on the debug run.
MC9S12HZ256 Data Sheet, Rev. 2.04
564
Freescale Semiconductor
Chapter 19 Debug Module (DBGV1)
Table 19-26. Breakpoint Setup
BEGIN
TRGSEL
DBGBRK
0
0
0
Fill trace buffer until trigger address
(no CPU breakpoint — keep running)
0
0
1
Fill trace buffer until trigger address, then a forced breakpoint
request occurs
0
1
0
Fill trace buffer until trigger opcode is about to execute
(no CPU breakpoint — keep running)
0
1
1
Fill trace buffer until trigger opcode about to execute, then a
tagged breakpoint request occurs
1
0
0
Start trace buffer at trigger address
(no CPU breakpoint — keep running)
1
0
1
Start trace buffer at trigger address, a forced breakpoint
request occurs when trace buffer is full
1
1
0
Start trace buffer at trigger opcode
(no CPU breakpoint — keep running)
1
1
1
Start trace buffer at trigger opcode, a forced breakpoint request
occurs when trace buffer is full
19.4.3.2
Type of Debug Run
Breakpoint Based on Comparator C
A breakpoint request to the CPU can be created if BKCEN in DBGC2 is set. Breakpoints based on a
successful comparator C match can be accomplished regardless of the mode of operation for comparator
A or B, and do not affect the status of the ARM bit. TAGC in DBGC2 is used to select either tagged or
forced breakpoint requests for comparator C. Breakpoints based on comparator C are disabled in LOOP1
mode.
NOTE
Because breakpoints cannot be disabled when the DBG is armed, one must
be careful to avoid an “infinite breakpoint loop” when using tagged-type C
breakpoints while the DBG is armed. If BDM breakpoints are selected,
executing a TRACE1 instruction before the GO instruction is the
recommended way to avoid re-triggering a breakpoint if one does not wish
to de-arm the DBG. If SWI breakpoints are selected, disarming the DBG in
the SWI interrupt service routine is the recommended way to avoid
re-triggering a breakpoint.
19.5
Resets
The DBG module is disabled after reset.
The DBG module cannot cause a MCU reset.
19.6
Interrupts
The DBG contains one interrupt source. If a breakpoint is requested and BDM in DBGC2 is cleared, an
SWI interrupt will be generated.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
565
Chapter 19 Debug Module (DBGV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
566
Freescale Semiconductor
Chapter 20
Interrupt (INTV1)
20.1
Introduction
This section describes the functionality of the interrupt (INT) sub-block of the S12 core platform.
A block diagram of the interrupt sub-block is shown in Figure 20-1.
INT
WRITE DATA BUS
HPRIO (OPTIONAL)
HIGHEST PRIORITY
I-INTERRUPT
INTERRUPTS
XMASK
INTERRUPT INPUT REGISTERS
AND CONTROL REGISTERS
READ DATA BUS
IMASK
QUALIFIED
INTERRUPTS
HPRIO VECTOR
WAKEUP
INTERRUPT PENDING
RESET FLAGS
PRIORITY DECODER
VECTOR REQUEST
VECTOR ADDRESS
Figure 20-1. INT Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
567
Chapter 20 Interrupt (INTV1)
The interrupt sub-block decodes the priority of all system exception requests and provides the applicable
vector for processing the exception. The INT supports I-bit maskable and X-bit maskable interrupts, a
non-maskable unimplemented opcode trap, a non-maskable software interrupt (SWI) or background debug
mode request, and three system reset vector requests. All interrupt related exception requests are managed
by the interrupt sub-block (INT).
20.1.1
Features
The INT includes these features:
• Provides two to 122 I-bit maskable interrupt vectors (0xFF00–0xFFF2)
• Provides one X-bit maskable interrupt vector (0xFFF4)
• Provides a non-maskable software interrupt (SWI) or background debug mode request vector
(0xFFF6)
• Provides a non-maskable unimplemented opcode trap (TRAP) vector (0xFFF8)
• Provides three system reset vectors (0xFFFA–0xFFFE) (reset, CMR, and COP)
• Determines the appropriate vector and drives it onto the address bus at the appropriate time
• Signals the CPU that interrupts are pending
• Provides control registers which allow testing of interrupts
• Provides additional input signals which prevents requests for servicing I and X interrupts
• Wakes the system from stop or wait mode when an appropriate interrupt occurs or whenever XIRQ
is active, even if XIRQ is masked
• Provides asynchronous path for all I and X interrupts, (0xFF00–0xFFF4)
• (Optional) selects and stores the highest priority I interrupt based on the value written into the
HPRIO register
20.1.2
Modes of Operation
The functionality of the INT sub-block in various modes of operation is discussed in the subsections that
follow.
• Normal operation
The INT operates the same in all normal modes of operation.
• Special operation
Interrupts may be tested in special modes through the use of the interrupt test registers.
• Emulation modes
The INT operates the same in emulation modes as in normal modes.
• Low power modes
See Section 20.4.1, “Low-Power Modes,” for details
MC9S12HZ256 Data Sheet, Rev. 2.04
568
Freescale Semiconductor
Chapter 20 Interrupt (INTV1)
20.2
External Signal Description
Most interfacing with the interrupt sub-block is done within the core. However, the interrupt does receive
direct input from the multiplexed external bus interface (MEBI) sub-block of the core for the IRQ and
XIRQ pin data.
20.3
Memory Map and Register Definition
Detailed descriptions of the registers and associated bits are given in the subsections that follow.
20.3.1
Module Memory Map
Table 20-1. INT Memory Map
Address
Offset
20.3.2
20.3.2.1
R
Use
Access
0x0015
Interrupt Test Control Register (ITCR)
R/W
0x0016
Interrupt Test Registers (ITEST)
R/W
0x001F
Highest Priority Interrupt (Optional) (HPRIO)
R/W
Register Descriptions
Interrupt Test Control Register
7
6
5
0
0
0
4
3
2
1
0
WRTINT
ADR3
ADR2
ADR1
ADR0
0
1
1
1
1
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 20-2. Interrupt Test Control Register (ITCR)
Read: See individual bit descriptions
Write: See individual bit descriptions
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
569
Chapter 20 Interrupt (INTV1)
Table 20-2. ITCR Field Descriptions
Field
Description
4
WRTINT
Write to the Interrupt Test Registers
Read: anytime
Write: only in special modes and with I-bit mask and X-bit mask set.
0 Disables writes to the test registers; reads of the test registers will return the state of the interrupt inputs.
1 Disconnect the interrupt inputs from the priority decoder and use the values written into the ITEST registers
instead.
Note: Any interrupts which are pending at the time that WRTINT is set will remain until they are overwritten.
3:0
ADR[3:0]
Test Register Select Bits
Read: anytime
Write: anytime
These bits determine which test register is selected on a read or write. The hexadecimal value written here will
be the same as the upper nibble of the lower byte of the vector selects. That is, an “F” written into ADR[3:0] will
select vectors 0xFFFE–0xFFF0 while a “7” written to ADR[3:0] will select vectors 0xFF7E–0xFF70.
20.3.2.2
Interrupt Test Registers
7
6
5
4
3
2
1
0
INTE
INTC
INTA
INT8
INT6
INT4
INT2
INT0
0
0
0
0
0
0
0
0
R
W
Reset
= Unimplemented or Reserved
Figure 20-3. Interrupt TEST Registers (ITEST)
Read: Only in special modes. Reads will return either the state of the interrupt inputs of the interrupt
sub-block (WRTINT = 0) or the values written into the TEST registers (WRTINT = 1). Reads will always
return 0s in normal modes.
Write: Only in special modes and with WRTINT = 1 and CCR I mask = 1.
Table 20-3. ITEST Field Descriptions
Field
Description
7:0
INT[E:0]
Interrupt TEST Bits — These registers are used in special modes for testing the interrupt logic and priority
independent of the system configuration. Each bit is used to force a specific interrupt vector by writing it to a
logic 1 state. Bits are named INTE through INT0 to indicate vectors 0xFFxE through 0xFFx0. These bits can be
written only in special modes and only with the WRTINT bit set (logic 1) in the interrupt test control register
(ITCR). In addition, I interrupts must be masked using the I bit in the CCR. In this state, the interrupt input lines
to the interrupt sub-block will be disconnected and interrupt requests will be generated only by this register.
These bits can also be read in special modes to view that an interrupt requested by a system block (such as a
peripheral block) has reached the INT module.
There is a test register implemented for every eight interrupts in the overall system. All of the test registers share
the same address and are individually selected using the value stored in the ADR[3:0] bits of the interrupt test
control register (ITCR).
Note: When ADR[3:0] have the value of 0x000F, only bits 2:0 in the ITEST register will be accessible. That is,
vectors higher than 0xFFF4 cannot be tested using the test registers and bits 7:3 will always read as a
logic 0. If ADR[3:0] point to an unimplemented test register, writes will have no effect and reads will always
return a logic 0 value.
MC9S12HZ256 Data Sheet, Rev. 2.04
570
Freescale Semiconductor
Chapter 20 Interrupt (INTV1)
20.3.2.3
Highest Priority I Interrupt (Optional)
7
6
5
4
3
2
1
PSEL7
PSEL6
PSEL5
PSEL4
PSEL3
PSEL2
PSEL1
1
1
1
1
0
0
1
R
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 20-4. Highest Priority I Interrupt Register (HPRIO)
Read: Anytime
Write: Only if I mask in CCR = 1
Table 20-4. HPRIO Field Descriptions
Field
Description
7:1
PSEL[7:1]
Highest Priority I Interrupt Select Bits — The state of these bits determines which I-bit maskable interrupt will
be promoted to highest priority (of the I-bit maskable interrupts). To promote an interrupt, the user writes the least
significant byte of the associated interrupt vector address to this register. If an unimplemented vector address or
a non I-bit masked vector address (value higher than 0x00F2) is written, IRQ (0xFFF2) will be the default highest
priority interrupt.
20.4
Functional Description
The interrupt sub-block processes all exception requests made by the CPU. These exceptions include
interrupt vector requests and reset vector requests. Each of these exception types and their overall priority
level is discussed in the subsections below.
20.4.1
Low-Power Modes
The INT does not contain any user-controlled options for reducing power consumption. The operation of
the INT in low-power modes is discussed in the following subsections.
20.4.1.1
Operation in Run Mode
The INT does not contain any options for reducing power in run mode.
20.4.1.2
Operation in Wait Mode
Clocks to the INT can be shut off during system wait mode and the asynchronous interrupt path will be
used to generate the wake-up signal upon recognition of a valid interrupt or any XIRQ request.
20.4.1.3
Operation in Stop Mode
Clocks to the INT can be shut off during system stop mode and the asynchronous interrupt path will be
used to generate the wake-up signal upon recognition of a valid interrupt or any XIRQ request.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
571
Chapter 20 Interrupt (INTV1)
20.5
Resets
The INT supports three system reset exception request types: normal system reset or power-on-reset
request, crystal monitor reset request, and COP watchdog reset request. The type of reset exception request
must be decoded by the system and the proper request made to the core. The INT will then provide the
service routine address for the type of reset requested.
20.6
Interrupts
As shown in the block diagram in Figure 20-1, the INT contains a register block to provide interrupt status
and control, an optional highest priority I interrupt (HPRIO) block, and a priority decoder to evaluate
whether pending interrupts are valid and assess their priority.
20.6.1
Interrupt Registers
The INT registers are accessible only in special modes of operation and function as described in
Section 20.3.2.1, “Interrupt Test Control Register,” and Section 20.3.2.2, “Interrupt Test Registers,”
previously.
20.6.2
Highest Priority I-Bit Maskable Interrupt
When the optional HPRIO block is implemented, the user is allowed to promote a single I-bit maskable
interrupt to be the highest priority I interrupt. The HPRIO evaluates all interrupt exception requests and
passes the HPRIO vector to the priority decoder if the highest priority I interrupt is active. RTI replaces
the promoted interrupt source.
20.6.3
Interrupt Priority Decoder
The priority decoder evaluates all interrupts pending and determines their validity and priority. When the
CPU requests an interrupt vector, the decoder will provide the vector for the highest priority interrupt
request. Because the vector is not supplied until the CPU requests it, it is possible that a higher priority
interrupt request could override the original exception that caused the CPU to request the vector. In this
case, the CPU will receive the highest priority vector and the system will process this exception instead of
the original request.
NOTE
Care must be taken to ensure that all exception requests remain active until
the system begins execution of the applicable service routine; otherwise, the
exception request may not be processed.
If for any reason the interrupt source is unknown (e.g., an interrupt request becomes inactive after the
interrupt has been recognized but prior to the vector request), the vector address will default to that of the
last valid interrupt that existed during the particular interrupt sequence. If the CPU requests an interrupt
vector when there has never been a pending interrupt request, the INT will provide the software interrupt
(SWI) vector address.
MC9S12HZ256 Data Sheet, Rev. 2.04
572
Freescale Semiconductor
Chapter 20 Interrupt (INTV1)
20.7
Exception Priority
The priority (from highest to lowest) and address of all exception vectors issued by the INT upon request
by the CPU is shown in Table 20-5.
Table 20-5. Exception Vector Map and Priority
Vector Address
Source
0xFFFE–0xFFFF
System reset
0xFFFC–0xFFFD
Crystal monitor reset
0xFFFA–0xFFFB
COP reset
0xFFF8–0xFFF9
Unimplemented opcode trap
0xFFF6–0xFFF7
Software interrupt instruction (SWI) or BDM vector request
0xFFF4–0xFFF5
XIRQ signal
0xFFF2–0xFFF3
IRQ signal
0xFFF0–0xFF00
Device-specific I-bit maskable interrupt sources (priority in descending order)
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
573
Chapter 20 Interrupt (INTV1)
MC9S12HZ256 Data Sheet, Rev. 2.04
574
Freescale Semiconductor
Chapter 21
Multiplexed External Bus Interface (MEBIV3)
21.1
Introduction
This section describes the functionality of the multiplexed external bus interface (MEBI) sub-block of the
S12 core platform. The functionality of the module is closely coupled with the S12 CPU and the memory
map controller (MMC) sub-blocks.
Figure 21-1 is a block diagram of the MEBI. In Figure 21-1, the signals on the right hand side represent
pins that are accessible externally. On some chips, these may not all be bonded out.
The MEBI sub-block of the core serves to provide access and/or visibility to internal core data
manipulation operations including timing reference information at the external boundary of the core and/or
system. Depending upon the system operating mode and the state of bits within the control registers of the
MEBI, the internal 16-bit read and write data operations will be represented in 8-bit or 16-bit accesses
externally. Using control information from other blocks within the system, the MEBI will determine the
appropriate type of data access to be generated.
21.1.1
Features
The block name includes these distinctive features:
• External bus controller with four 8-bit ports A,B, E, and K
• Data and data direction registers for ports A, B, E, and K when used as general-purpose I/O
• Control register to enable/disable alternate functions on ports E and K
• Mode control register
• Control register to enable/disable pull resistors on ports A, B, E, and K
• Control register to enable/disable reduced output drive on ports A, B, E, and K
• Control register to configure external clock behavior
• Control register to configure IRQ pin operation
• Logic to capture and synchronize external interrupt pin inputs
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
575
Internal Bus
Addr[19:0]
EXT
BUS
I/F
CTL
Data[15:0]
ADDR
DATA
Port K
ADDR
PK[7:0]/ECS/XCS/X[19:14]
Port A
REGS
PA[7:0]/A[15:8]/
D[15:8]/D[7:0]
Port B
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
PB[7:0]/A[7:0]/
D[7:0]
(Control)
ADDR
DATA
CPU pipe info
PIPE CTL
IRQ interrupt
XIRQ interrupt
IRQ CTL
TAG CTL
BDM tag info
mode
Port E
ECLK CTL
PE[7:2]/NOACC/
IPIPE1/MODB/CLKTO
IPIPE0/MODA/
ECLK/
LSTRB/TAGLO
R/W
PE1/IRQ
PE0/XIRQ
BKGD
BKGD/MODC/TAGHI
Control signal(s)
Data signal (unidirectional)
Data signal (bidirectional)
Data bus (unidirectional)
Data bus (bidirectional)
Figure 21-1. MEBI Block Diagram
MC9S12HZ256 Data Sheet, Rev. 2.04
576
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.1.2
•
•
•
•
•
•
•
•
21.2
Modes of Operation
Normal expanded wide mode
Ports A and B are configured as a 16-bit multiplexed address and data bus and port E provides bus
control and status signals. This mode allows 16-bit external memory and peripheral devices to be
interfaced to the system.
Normal expanded narrow mode
Ports A and B are configured as a 16-bit address bus and port A is multiplexed with 8-bit data.
Port E provides bus control and status signals. This mode allows 8-bit external memory and
peripheral devices to be interfaced to the system.
Normal single-chip mode
There is no external expansion bus in this mode. The processor program is executed from internal
memory. Ports A, B, K, and most of E are available as general-purpose I/O.
Special single-chip mode
This mode is generally used for debugging single-chip operation, boot-strapping, or security
related operations. The active background mode is in control of CPU execution and BDM firmware
is waiting for additional serial commands through the BKGD pin. There is no external expansion
bus after reset in this mode.
Emulation expanded wide mode
Developers use this mode for emulation systems in which the users target application is normal
expanded wide mode.
Emulation expanded narrow mode
Developers use this mode for emulation systems in which the users target application is normal
expanded narrow mode.
Special test mode
Ports A and B are configured as a 16-bit multiplexed address and data bus and port E provides bus
control and status signals. In special test mode, the write protection of many control bits is lifted
so that they can be thoroughly tested without needing to go through reset.
Special peripheral mode
This mode is intended for Freescale Semiconductor factory testing of the system. The CPU is
inactive and an external (tester) bus master drives address, data, and bus control signals.
External Signal Description
In typical implementations, the MEBI sub-block of the core interfaces directly with external system pins.
Some pins may not be bonded out in all implementations.
Table 21-1 outlines the pin names and functions and gives a brief description of their operation reset state
of these pins and associated pull-ups or pull-downs is dependent on the mode of operation and on the
integration of this block at the chip level (chip dependent).
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
577
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
.
Table 21-1. External System Pins Associated With MEBI
Pin Name
BKGD/MODC/
TAGHI
PA7/A15/D15/D7
thru
PA0/A8/D8/D0
PB7/A7/D7
thru
PB0/A0/D0
PE7/NOACC
PE6/IPIPE1/
MODB/CLKTO
PE5/IPIPE0/MODA
Pin Functions
Description
MODC
At the rising edge on RESET, the state of this pin is registered into the MODC
bit to set the mode. (This pin always has an internal pullup.)
BKGD
Pseudo open-drain communication pin for the single-wire background debug
mode. There is an internal pull-up resistor on this pin.
TAGHI
When instruction tagging is on, a 0 at the falling edge of E tags the high half of
the instruction word being read into the instruction queue.
PA7–PA0
General-purpose I/O pins, see PORTA and DDRA registers.
A15–A8
High-order address lines multiplexed during ECLK low. Outputs except in
special peripheral mode where they are inputs from an external tester system.
D15–D8
High-order bidirectional data lines multiplexed during ECLK high in expanded
wide modes, special peripheral mode, and visible internal accesses (IVIS = 1)
in emulation expanded narrow mode. Direction of data transfer is generally
indicated by R/W.
D15/D7
thru
D8/D0
Alternate high-order and low-order bytes of the bidirectional data lines
multiplexed during ECLK high in expanded narrow modes and narrow accesses
in wide modes. Direction of data transfer is generally indicated by R/W.
PB7–PB0
General-purpose I/O pins, see PORTB and DDRB registers.
A7–A0
Low-order address lines multiplexed during ECLK low. Outputs except in
special peripheral mode where they are inputs from an external tester system.
D7–D0
Low-order bidirectional data lines multiplexed during ECLK high in expanded
wide modes, special peripheral mode, and visible internal accesses (with
IVIS = 1) in emulation expanded narrow mode. Direction of data transfer is
generally indicated by R/W.
PE7
General-purpose I/O pin, see PORTE and DDRE registers.
NOACC
CPU No Access output. Indicates whether the current cycle is a free cycle. Only
available in expanded modes.
MODB
At the rising edge of RESET, the state of this pin is registered into the MODB
bit to set the mode.
PE6
General-purpose I/O pin, see PORTE and DDRE registers.
IPIPE1
Instruction pipe status bit 1, enabled by PIPOE bit in PEAR.
CLKTO
System clock test output. Only available in special modes. PIPOE = 1 overrides
this function. The enable for this function is in the clock module.
MODA
At the rising edge on RESET, the state of this pin is registered into the MODA
bit to set the mode.
PE5
General-purpose I/O pin, see PORTE and DDRE registers.
IPIPE0
Instruction pipe status bit 0, enabled by PIPOE bit in PEAR.
MC9S12HZ256 Data Sheet, Rev. 2.04
578
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
Table 21-1. External System Pins Associated With MEBI (continued)
Pin Name
PE4/ECLK
PE3/LSTRB/ TAGLO
PE2/R/W
PE1/IRQ
PE0/XIRQ
PK7/ECS
PK6/XCS
PK5/X19
thru
PK0/X14
Pin Functions
Description
PE4
General-purpose I/O pin, see PORTE and DDRE registers.
ECLK
Bus timing reference clock, can operate as a free-running clock at the system
clock rate or to produce one low-high clock per visible access, with the high
period stretched for slow accesses. ECLK is controlled by the NECLK bit in
PEAR, the IVIS bit in MODE, and the ESTR bit in EBICTL.
PE3
General-purpose I/O pin, see PORTE and DDRE registers.
LSTRB
Low strobe bar, 0 indicates valid data on D7–D0.
SZ8
In special peripheral mode, this pin is an input indicating the size of the data
transfer (0 = 16-bit; 1 = 8-bit).
TAGLO
In expanded wide mode or emulation narrow modes, when instruction tagging
is on and low strobe is enabled, a 0 at the falling edge of E tags the low half of
the instruction word being read into the instruction queue.
PE2
General-purpose I/O pin, see PORTE and DDRE registers.
R/W
Read/write, indicates the direction of internal data transfers. This is an output
except in special peripheral mode where it is an input.
PE1
General-purpose input-only pin, can be read even if IRQ enabled.
IRQ
Maskable interrupt request, can be level sensitive or edge sensitive.
PE0
General-purpose input-only pin.
XIRQ
Non-maskable interrupt input.
PK7
General-purpose I/O pin, see PORTK and DDRK registers.
ECS
Emulation chip select
PK6
General-purpose I/O pin, see PORTK and DDRK registers.
XCS
External data chip select
PK5–PK0
General-purpose I/O pins, see PORTK and DDRK registers.
X19–X14
Memory expansion addresses
Detailed descriptions of these pins can be found in the device overview chapter.
21.3
Memory Map and Register Definition
A summary of the registers associated with the MEBI sub-block is shown in Table 21-2. Detailed
descriptions of the registers and bits are given in the subsections that follow. On most chips the registers
are mappable. Therefore, the upper bits may not be all 0s as shown in the table and descriptions.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
579
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.1
Module Memory Map
Table 21-2. MEBI Memory Map
Address
Offset
21.3.2
21.3.2.1
Use
Access
0x0000
Port A Data Register (PORTA)
R/W
0x0001
Port B Data Register (PORTB)
R/W
0x0002
Data Direction Register A (DDRA)
R/W
0x0003
Data Direction Register B (DDRB)
R/W
0x0004
Reserved
R
0x0005
Reserved
R
0x0006
Reserved
R
0x0007
Reserved
R
0x0008
Port E Data Register (PORTE)
R/W
0x0009
Data Direction Register E (DDRE)
R/W
0x000A
Port E Assignment Register (PEAR)
R/W
0x000B
Mode Register (MODE)
R/W
0x000C
Pull Control Register (PUCR)
R/W
0x000D
Reduced Drive Register (RDRIV)
R/W
0x000E
External Bus Interface Control Register (EBICTL)
R/W
0x000F
Reserved
0x001E
IRQ Control Register (IRQCR)
R/W
0x00032
Port K Data Register (PORTK)
R/W
0x00033
Data Direction Register K (DDRK)
R/W
R
Register Descriptions
Port A Data Register (PORTA)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
AB/DB14
AB/DB13
AB/DB12
AB/DB11
AB/DB10
AB/DB9
AB/DB8
AB9 and
DB9/DB1
AB8 and
DB8/DB0
R
W
Reset
Single Chip
Expanded Wide,
Emulation Narrow with AB/DB15
IVIS, and Peripheral
Expanded Narrow AB15 and AB14 and AB13 and AB12 and AB11 and AB10 and
DB15/DB7 DB14/DB6 DB13/DB5 DB12/DB4 DB11/DB3 DB10/DB2
Figure 21-2. Port A Data Register (PORTA)
MC9S12HZ256 Data Sheet, Rev. 2.04
580
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
Read: Anytime when register is in the map
Write: Anytime when register is in the map
Port A bits 7 through 0 are associated with address lines A15 through A8 respectively and data lines
D15/D7 through D8/D0 respectively. When this port is not used for external addresses such as in
single-chip mode, these pins can be used as general-purpose I/O. Data direction register A (DDRA)
determines the primary direction of each pin. DDRA also determines the source of data for a read of
PORTA.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
NOTE
To ensure that you read the value present on the PORTA pins, always wait
at least one cycle after writing to the DDRA register before reading from the
PORTA register.
21.3.2.2
Port B Data Register (PORTB)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
AB/DB7
AB/DB6
AB/DB5
AB/DB4
AB/DB3
AB/DB2
AB/DB1
AB/DB0
AB7
AB6
AB5
AB4
AB3
AB2
AB1
AB0
R
W
Reset
Single Chip
Expanded Wide,
Emulation Narrow with
IVIS, and Peripheral
Expanded Narrow
Figure 21-3. Port A Data Register (PORTB)
Read: Anytime when register is in the map
Write: Anytime when register is in the map
Port B bits 7 through 0 are associated with address lines A7 through A0 respectively and data lines D7
through D0 respectively. When this port is not used for external addresses, such as in single-chip mode,
these pins can be used as general-purpose I/O. Data direction register B (DDRB) determines the primary
direction of each pin. DDRB also determines the source of data for a read of PORTB.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
NOTE
To ensure that you read the value present on the PORTB pins, always wait
at least one cycle after writing to the DDRB register before reading from the
PORTB register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
581
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.3
Data Direction Register A (DDRA)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 21-4. Data Direction Register A (DDRA)
Read: Anytime when register is in the map
Write: Anytime when register is in the map
This register controls the data direction for port A. When port A is operating as a general-purpose I/O port,
DDRA determines the primary direction for each port A pin. A 1 causes the associated port pin to be an
output and a 0 causes the associated pin to be a high-impedance input. The value in a DDR bit also affects
the source of data for reads of the corresponding PORTA register. If the DDR bit is 0 (input) the buffered
pin input state is read. If the DDR bit is 1 (output) the associated port data register bit state is read.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally. It is reset to 0x00 so the DDR does not override the three-state control
signals.
Table 21-3. DDRA Field Descriptions
Field
7:0
DDRA
Description
Data Direction Port A
0 Configure the corresponding I/O pin as an input
1 Configure the corresponding I/O pin as an output
MC9S12HZ256 Data Sheet, Rev. 2.04
582
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.4
Data Direction Register B (DDRB)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 21-5. Data Direction Register B (DDRB)
Read: Anytime when register is in the map
Write: Anytime when register is in the map
This register controls the data direction for port B. When port B is operating as a general-purpose I/O port,
DDRB determines the primary direction for each port B pin. A 1 causes the associated port pin to be an
output and a 0 causes the associated pin to be a high-impedance input. The value in a DDR bit also affects
the source of data for reads of the corresponding PORTB register. If the DDR bit is 0 (input) the buffered
pin input state is read. If the DDR bit is 1 (output) the associated port data register bit state is read.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally. It is reset to 0x00 so the DDR does not override the three-state control
signals.
Table 21-4. DDRB Field Descriptions
Field
7:0
DDRB
Description
Data Direction Port B
0 Configure the corresponding I/O pin as an input
1 Configure the corresponding I/O pin as an output
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
583
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.5
R
Reserved Registers
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 21-6. Reserved Register
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 21-7. Reserved Register
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 21-8. Reserved Register
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 21-9. Reserved Register
These register locations are not used (reserved). All unused registers and bits in this block return logic 0s
when read. Writes to these registers have no effect.
These registers are not in the on-chip map in special peripheral mode.
MC9S12HZ256 Data Sheet, Rev. 2.04
584
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.6
Port E Data Register (PORTE)
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
Bit 1
Bit 0
0
0
0
0
0
0
u
u
NOACC
MODB
or IPIPE1
or CLKTO
MODA
or IPIPE0
ECLK
LSTRB
or TAGLO
R/W
IRQ
XIRQ
R
W
Reset
Alternate
Pin Function
= Unimplemented or Reserved
u = Unaffected by reset
Figure 21-10. Port E Data Register (PORTE)
Read: Anytime when register is in the map
Write: Anytime when register is in the map
Port E is associated with external bus control signals and interrupt inputs. These include mode select
(MODB/IPIPE1, MODA/IPIPE0), E clock, size (LSTRB/TAGLO), read/write (R/W), IRQ, and XIRQ.
When not used for one of these specific functions, port E pins 7:2 can be used as general-purpose I/O and
pins 1:0 can be used as general-purpose input. The port E assignment register (PEAR) selects the function
of each pin and DDRE determines whether each pin is an input or output when it is configured to be
general-purpose I/O. DDRE also determines the source of data for a read of PORTE.
Some of these pins have software selectable pull resistors. IRQ and XIRQ can only be pulled up whereas
the polarity of the PE7, PE4, PE3, and PE2 pull resistors are determined by chip integration. Please refer
to the device overview chapter (Signal Property Summary) to determine the polarity of these resistors.
A single control bit enables the pull devices for all of these pins when they are configured as inputs.
This register is not in the on-chip map in special peripheral mode or in expanded modes when the EME
bit is set. Therefore, these accesses will be echoed externally.
NOTE
It is unwise to write PORTE and DDRE as a word access. If you are
changing port E pins from being inputs to outputs, the data may have extra
transitions during the write. It is best to initialize PORTE before enabling as
outputs.
NOTE
To ensure that you read the value present on the PORTE pins, always wait
at least one cycle after writing to the DDRE register before reading from the
PORTE register.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
585
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.7
Data Direction Register E (DDRE)
7
6
5
4
3
2
Bit 7
6
5
4
3
Bit 2
0
0
0
0
0
0
R
1
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 21-11. Data Direction Register E (DDRE)
Read: Anytime when register is in the map
Write: Anytime when register is in the map
Data direction register E is associated with port E. For bits in port E that are configured as general-purpose
I/O lines, DDRE determines the primary direction of each of these pins. A 1 causes the associated bit to
be an output and a 0 causes the associated bit to be an input. Port E bit 1 (associated with IRQ) and bit 0
(associated with XIRQ) cannot be configured as outputs. Port E, bits 1 and 0, can be read regardless of
whether the alternate interrupt function is enabled. The value in a DDR bit also affects the source of data
for reads of the corresponding PORTE register. If the DDR bit is 0 (input) the buffered pin input state is
read. If the DDR bit is 1 (output) the associated port data register bit state is read.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally. Also, it is not in the map in expanded modes while the EME control bit
is set.
Table 21-5. DDRE Field Descriptions
Field
Description
7:2
DDRE
Data Direction Port E
0 Configure the corresponding I/O pin as an input
1 Configure the corresponding I/O pin as an output
Note: It is unwise to write PORTE and DDRE as a word access. If you are changing port E pins from inputs to
outputs, the data may have extra transitions during the write. It is best to initialize PORTE before enabling
as outputs.
MC9S12HZ256 Data Sheet, Rev. 2.04
586
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.8
Port E Assignment Register (PEAR)
7
6
R
5
4
3
2
PIPOE
NECLK
LSTRE
RDWE
0
NOACCE
1
0
0
0
W
Reset
Special Single Chip
0
0
0
0
0
0
0
0
Special Test
0
0
1
0
1
1
0
0
Peripheral
0
0
0
0
0
0
0
0
Emulation Expanded
Narrow
1
0
1
0
1
1
0
0
Emulation Expanded
Wide
1
0
1
0
1
1
0
0
Normal Single Chip
0
0
0
1
0
0
0
0
Normal Expanded
Narrow
0
0
0
0
0
0
0
0
Normal Expanded Wide
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 21-12. Port E Assignment Register (PEAR)
Read: Anytime (provided this register is in the map).
Write: Each bit has specific write conditions. Please refer to the descriptions of each bit on the following
pages.
Port E serves as general-purpose I/O or as system and bus control signals. The PEAR register is used to
choose between the general-purpose I/O function and the alternate control functions. When an alternate
control function is selected, the associated DDRE bits are overridden.
The reset condition of this register depends on the mode of operation because bus control signals are
needed immediately after reset in some modes. In normal single-chip mode, no external bus control signals
are needed so all of port E is configured for general-purpose I/O. In normal expanded modes, only the E
clock is configured for its alternate bus control function and the other bits of port E are configured for
general-purpose I/O. As the reset vector is located in external memory, the E clock is required for this
access. R/W is only needed by the system when there are external writable resources. If the normal
expanded system needs any other bus control signals, PEAR would need to be written before any access
that needed the additional signals. In special test and emulation modes, IPIPE1, IPIPE0, E, LSTRB, and
R/W are configured out of reset as bus control signals.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
587
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
Table 21-6. PEAR Field Descriptions
Field
Description
7
NOACCE
CPU No Access Output Enable
Normal: write once
Emulation: write never
Special: write anytime
1 The associated pin (port E, bit 7) is general-purpose I/O.
0 The associated pin (port E, bit 7) is output and indicates whether the cycle is a CPU free cycle.
This bit has no effect in single-chip or special peripheral modes.
5
PIPOE
Pipe Status Signal Output Enable
Normal: write once
Emulation: write never
Special: write anytime.
0 The associated pins (port E, bits 6:5) are general-purpose I/O.
1 The associated pins (port E, bits 6:5) are outputs and indicate the state of the instruction queue
This bit has no effect in single-chip or special peripheral modes.
4
NECLK
No External E Clock
Normal and special: write anytime
Emulation: write never
0 The associated pin (port E, bit 4) is the external E clock pin. External E clock is free-running if ESTR = 0
1 The associated pin (port E, bit 4) is a general-purpose I/O pin.
External E clock is available as an output in all modes.
3
LSTRE
Low Strobe (LSTRB) Enable
Normal: write once
Emulation: write never
Special: write anytime.
0 The associated pin (port E, bit 3) is a general-purpose I/O pin.
1 The associated pin (port E, bit 3) is configured as the LSTRB bus control output. If BDM tagging is enabled,
TAGLO is multiplexed in on the rising edge of ECLK and LSTRB is driven out on the falling edge of ECLK.
This bit has no effect in single-chip, peripheral, or normal expanded narrow modes.
Note: LSTRB is used during external writes. After reset in normal expanded mode, LSTRB is disabled to provide
an extra I/O pin. If LSTRB is needed, it should be enabled before any external writes. External reads do
not normally need LSTRB because all 16 data bits can be driven even if the system only needs 8 bits of
data.
2
RDWE
Read/Write Enable
Normal: write once
Emulation: write never
Special: write anytime
0 The associated pin (port E, bit 2) is a general-purpose I/O pin.
1 The associated pin (port E, bit 2) is configured as the R/W pin
This bit has no effect in single-chip or special peripheral modes.
Note: R/W is used for external writes. After reset in normal expanded mode, R/W is disabled to provide an extra
I/O pin. If R/W is needed it should be enabled before any external writes.
MC9S12HZ256 Data Sheet, Rev. 2.04
588
Freescale Semiconductor
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
21.3.2.9
Mode Register (MODE)
7
6
5
1
0
MODC
MODB
MODA
EMK
EME
Special Single Chip
0
0
0
0
0
0
0
0
Emulation Expanded
Narrow
0
0
1
0
1
0
1
1
Special Test
0
1
0
0
1
0
0
0
Emulation Expanded
Wide
0
1
1
0
1
0
1
1
Normal Single Chip
1
0
0
0
0
0
0
0
Normal Expanded
Narrow
1
0
1
0
0
0
0
0
Peripheral
1
1
0
0
0
0
0
0
Normal Expanded Wide
1
1
1
0
0
0
0
0
R
4
3
0
2
0
IVIS
W
Reset
= Unimplemented or Reserved
Figure 21-13. Mode Register (MODE)
Read: Anytime (provided this register is in the map).
Write: Each bit has specific write conditions. Please refer to the descriptions of each bit on the following
pages.
The MODE register is used to establish the operating mode and other miscellaneous functions (i.e.,
internal visibility and emulation of port E and K).
In special peripheral mode, this register is not accessible but it is reset as shown to system configuration
features. Changes to bits in the MODE register are delayed one cycle after the write.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
589
Chapter 21 Multiplexed External Bus Interface (MEBIV3)
Table 21-7. MODE Field Descriptions
Field
Description
7:5
MOD[C:A]
Mode Select Bits — These bits indicate the current operating mode.
If MODA = 1, then MODC, MODB, and MODA are write never.
If MODC