Freescale MC9S08AC8 8-bit hcs08 central processor unit (cpu) Datasheet

MC9S08AC16
MC9S08AC8
S9S08AW16A
S9S08AW8A
Data Sheet: Advanced Information
HCS08
Microcontrollers
MC9S08AC16
Rev. 0
12/2007
freescale.com
PRELIMINARY
MC9S08AC16 Series Features
MC9S08AC16 Series Devices
•
•
Consumer & Industrial
— MC9S08AC16
— MC9S08AC8
Automotive
— S9S08AW16A
— S9S08AW8A
Peripherals
•
•
•
•
8-Bit HCS08 Central Processor Unit (CPU)
•
•
•
•
•
•
•
40-MHz HCS08 CPU (central processor unit)
20-MHz internal bus frequency
HC08 instruction set with added BGND
instruction
Background debugging system
Breakpoint capability to allow single breakpoint
setting during in-circuit debugging (plus two
more breakpoints in on-chip debug module)
Debug module containing two comparators and
nine trigger modes. Eight deep FIFO for storing
change-of-flow addresses and event-only data.
Debug module supports both tag and force
breakpoints.
Support for up to 32 interrupt/reset sources
Memory Options
•
•
Up to 16 KB of on-chip in-circuit programmable
FLASH memory with block protection and
security options
Up to 1 KB of on-chip RAM
Clock Source Options
•
Clock source options include crystal, resonator,
external clock, or internally generated clock
with precision NVM trimming
System Protection
•
•
•
•
Optional computer operating properly (COP)
reset with option to run from independent
internal clock source or bus clock
Low-voltage detection with reset or interrupt
Illegal opcode detection with reset
Illegal address detection with reset
•
•
ADC — 8-channel, 10-bit analog-to-digital
converter with automatic compare function
SCI — Two serial communications interface
modules with optional 13-bit break
SPI — Serial peripheral interface module
IIC — Inter-integrated circuit bus module to
operate at up to 100 kbps with maximum bus
loading; capable of higher baud rates with
reduced loading
Timers — Three1 16-bit timer/pulse-width
modulator (TPM) modules — Two1 2-channel
and one 4-channel; each has selectable input
capture, output compare, and edge-aligned
PWM capability on each channel. Each timer
module may be configured for buffered,
centered PWM (CPWM) on all channels
KBI — 7-pin keyboard interrupt module
Input/Output
•
•
•
•
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Up to 38 general-purpose input/output (I/O)
pins
Software selectable pullups on ports when
used as inputs
Software selectable slew rate control on ports
when used as outputs
Software selectable drive strength on ports
when used as outputs
Master reset pin and power-on reset (POR)
Internal pullup on RESET, IRQ, and BKGD/MS
pins to reduce customer system cost
Package Options
•
•
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48-pin quad flat no-lead package (QFN)
44-pin low-profile quad flat package (LQFP)
32-pin low-profile quad flat package (LQFP)
Power-Saving Modes
•
Wait plus two stops
1. MC9S08AC16 and MC9S08AC8 devices only.
MC9S08AC16 Series Data Sheet
Covers MC9S08AC16
MC9S08AC8
S9S08AW16A
S9S08AW8A
MC9S08AC16
Rev. 0
12/2007
PRELIMINARY
Revision History
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. For your
convenience, the page number designators have been linked to the appropriate location.
Revision
Number
Revision
Date
0
12/2007
Description of Changes
Initial Release.
This product incorporates SuperFlash® technology licensed from SST.
Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
© Freescale Semiconductor, Inc., 2006. All rights reserved.
MC9S08AC16 Series Data Sheet, Rev. 0
6
PRELIMINARY
Freescale Semiconductor
List of Chapters
Chapter
Title
Page
Chapter 1
Introduction.............................................................................. 19
Chapter 2
Pins and Connections ............................................................. 25
Chapter 3
Modes of Operation ................................................................. 35
Chapter 4
Memory ..................................................................................... 41
Chapter 5
Resets, Interrupts, and System Configuration ..................... 63
Chapter 6
Parallel Input/Output ............................................................... 81
Chapter 7
Central Processor Unit (S08CPUV2) .................................... 111
Chapter 8
Internal Clock Generator (S08ICGV4) .................................. 131
Chapter 9
Keyboard Interrupt (S08KBIV1) ............................................ 159
Chapter 10
Timer/PWM (S08TPMV3) ....................................................... 165
Chapter 11
Serial Communications Interface (S08SCIV4)..................... 193
Chapter 12
Serial Peripheral Interface (S08SPIV3) ................................ 213
Chapter 13
Inter-Integrated Circuit (S08IICV2) ....................................... 229
Chapter 14
Analog-to-Digital Converter (S08ADC10V1)........................ 249
Chapter 15
Development Support ........................................................... 277
Appendix A
Electrical Characteristics and Timing Specifications ....... 299
Appendix B
Ordering Information and Mechanical Drawings............... 325
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
7
Contents
Section Number
Title
Page
Chapter 1
Introduction
1.1
1.2
1.3
Overview .........................................................................................................................................19
MCU Block Diagrams .....................................................................................................................20
System Clock Distribution ..............................................................................................................22
Chapter 2
Pins and Connections
2.1
2.2
2.3
Introduction .....................................................................................................................................25
Device Pin Assignment ...................................................................................................................25
Recommended System Connections ...............................................................................................29
2.3.1 Power (VDD, 2 x VSS, VDDAD, VSSAD) ............................................................................31
2.3.2 Oscillator (XTAL, EXTAL) ..............................................................................................31
2.3.3 RESET ..............................................................................................................................31
2.3.4 Background/Mode Select (BKGD/MS) ............................................................................32
2.3.5 ADC Reference Pins (VREFH, VREFL) ..............................................................................32
2.3.6 External Interrupt Pin (IRQ) .............................................................................................32
2.3.7 General-Purpose I/O and Peripheral Ports ........................................................................33
Chapter 3
Modes of Operation
3.1
3.2
3.3
3.4
3.5
3.6
Introduction .....................................................................................................................................35
Features ...........................................................................................................................................35
Run Mode ........................................................................................................................................35
Active Background Mode ................................................................................................................35
Wait Mode .......................................................................................................................................36
Stop Modes ......................................................................................................................................36
3.6.1 Stop2 Mode .......................................................................................................................37
3.6.2 Stop3 Mode .......................................................................................................................38
3.6.3 Active BDM Enabled in Stop Mode .................................................................................38
3.6.4 LVD Enabled in Stop Mode ..............................................................................................39
3.6.5 On-Chip Peripheral Modules in Stop Modes ....................................................................39
Chapter 4
Memory
4.1
MC9S08AC16 Series Memory Map ...............................................................................................41
4.1.1 Reset and Interrupt Vector Assignments ...........................................................................42
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
9
Section Number
4.2
4.3
4.4
4.5
4.6
Title
Page
Register Addresses and Bit Assignments ........................................................................................43
RAM ................................................................................................................................................49
FLASH ............................................................................................................................................50
4.4.1 Features .............................................................................................................................50
4.4.2 Program and Erase Times .................................................................................................50
4.4.3 Program and Erase Command Execution .........................................................................51
4.4.4 Burst Program Execution ..................................................................................................52
4.4.5 Access Errors ....................................................................................................................54
4.4.6 FLASH Block Protection ..................................................................................................54
4.4.7 Vector Redirection ............................................................................................................55
Security ............................................................................................................................................55
FLASH Registers and Control Bits .................................................................................................57
4.6.1 FLASH Clock Divider Register (FCDIV) ........................................................................57
4.6.2 FLASH Options Register (FOPT and NVOPT) ................................................................58
4.6.3 FLASH Configuration Register (FCNFG) ........................................................................59
4.6.4 FLASH Protection Register (FPROT and NVPROT) .......................................................60
4.6.5 FLASH Status Register (FSTAT) ......................................................................................60
4.6.6 FLASH Command Register (FCMD) ...............................................................................62
Chapter 5
Resets, Interrupts, and System Configuration
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
Introduction .....................................................................................................................................63
Features ...........................................................................................................................................63
MCU Reset ......................................................................................................................................63
Computer Operating Properly (COP) Watchdog .............................................................................64
Interrupts .........................................................................................................................................65
5.5.1 Interrupt Stack Frame .......................................................................................................66
5.5.2 External Interrupt Request (IRQ) Pin ...............................................................................66
5.5.3 Interrupt Vectors, Sources, and Local Masks ....................................................................67
Low-Voltage Detect (LVD) System ................................................................................................69
5.6.1 Power-On Reset Operation ...............................................................................................69
5.6.2 LVD Reset Operation ........................................................................................................69
5.6.3 LVD Interrupt Operation ...................................................................................................69
5.6.4 Low-Voltage Warning (LVW) ...........................................................................................69
Real-Time Interrupt (RTI) ...............................................................................................................69
MCLK Output .................................................................................................................................70
Reset, Interrupt, and System Control Registers and Control Bits ...................................................70
5.9.1 Interrupt Pin Request Status and Control Register (IRQSC) ............................................71
5.9.2 System Reset Status Register (SRS) .................................................................................72
5.9.3 System Background Debug Force Reset Register (SBDFR) ............................................73
5.9.4 System Options Register (SOPT) .....................................................................................74
5.9.5 System MCLK Control Register (SMCLK) .....................................................................75
MC9S08AC16 Series Data Sheet, Rev. 0
10
PRELIMINARY
Freescale Semiconductor
Section Number
5.9.6
5.9.7
5.9.8
5.9.9
5.9.10
Title
Page
System Device Identification Register (SDIDH, SDIDL) ................................................76
System Real-Time Interrupt Status and Control Register (SRTISC) ................................77
System Power Management Status and Control 1 Register (SPMSC1) ...........................78
System Power Management Status and Control 2 Register (SPMSC2) ...........................79
System Options Register 2 (SOPT2) ................................................................................80
Chapter 6
Parallel Input/Output
6.1
6.2
6.3
6.4
6.5
6.6
6.7
Introduction .....................................................................................................................................81
Features ...........................................................................................................................................83
Pin Descriptions ..............................................................................................................................83
6.3.1 Port A ................................................................................................................................83
6.3.2 Port B ................................................................................................................................84
6.3.3 Port C ................................................................................................................................84
6.3.4 Port D ................................................................................................................................85
6.3.5 Port E ................................................................................................................................85
6.3.6 Port F .................................................................................................................................86
6.3.7 Port G ................................................................................................................................86
Parallel I/O Control .........................................................................................................................87
Pin Control ......................................................................................................................................88
6.5.1 Internal Pullup Enable .......................................................................................................88
6.5.2 Output Slew Rate Control Enable .....................................................................................88
6.5.3 Output Drive Strength Select ............................................................................................88
Pin Behavior in Stop Modes ............................................................................................................89
Parallel I/O and Pin Control Registers ............................................................................................89
6.7.1 Port A I/O Registers (PTAD and PTADD) .......................................................................89
6.7.2 Port A Pin Control Registers (PTAPE, PTASE, PTADS) .................................................90
6.7.3 Port B I/O Registers (PTBD and PTBDD) .......................................................................92
6.7.4 Port B Pin Control Registers (PTBPE, PTBSE, PTBDS) .................................................93
6.7.5 Port C I/O Registers (PTCD and PTCDD) .......................................................................95
6.7.6 Port C Pin Control Registers (PTCPE, PTCSE, PTCDS) .................................................96
6.7.7 Port D I/O Registers (PTDD and PTDDD) .......................................................................98
6.7.8 Port D Pin Control Registers (PTDPE, PTDSE, PTDDS) ................................................99
6.7.9 Port E I/O Registers (PTED and PTEDD) ......................................................................101
6.7.10 Port E Pin Control Registers (PTEPE, PTESE, PTEDS) ................................................102
6.7.11 Port F I/O Registers (PTFD and PTFDD) .......................................................................104
6.7.12 Port F Pin Control Registers (PTFPE, PTFSE, PTFDS) ................................................105
6.7.13 Port G I/O Registers (PTGD and PTGDD) .....................................................................107
6.7.14 Port G Pin Control Registers (PTGPE, PTGSE, PTGDS) ..............................................108
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
11
Section Number
Title
Page
Chapter 7
Central Processor Unit (S08CPUV2)
7.1
7.2
7.3
7.4
7.5
Introduction ...................................................................................................................................111
7.1.1 Features ...........................................................................................................................111
Programmer’s Model and CPU Registers .....................................................................................112
7.2.1 Accumulator (A) .............................................................................................................112
7.2.2 Index Register (H:X) .......................................................................................................112
7.2.3 Stack Pointer (SP) ...........................................................................................................113
7.2.4 Program Counter (PC) ....................................................................................................113
7.2.5 Condition Code Register (CCR) .....................................................................................113
Addressing Modes .........................................................................................................................115
7.3.1 Inherent Addressing Mode (INH) ...................................................................................115
7.3.2 Relative Addressing Mode (REL) ...................................................................................115
7.3.3 Immediate Addressing Mode (IMM) ..............................................................................115
7.3.4 Direct Addressing Mode (DIR) ......................................................................................115
7.3.5 Extended Addressing Mode (EXT) ................................................................................116
7.3.6 Indexed Addressing Mode ..............................................................................................116
Special Operations .........................................................................................................................117
7.4.1 Reset Sequence ...............................................................................................................117
7.4.2 Interrupt Sequence ..........................................................................................................117
7.4.3 Wait Mode Operation ......................................................................................................118
7.4.4 Stop Mode Operation ......................................................................................................118
7.4.5 BGND Instruction ...........................................................................................................119
HCS08 Instruction Set Summary ..................................................................................................120
Chapter 8
Internal Clock Generator (S08ICGV4)
8.1
8.2
8.3
Introduction ...................................................................................................................................133
8.1.1 Features ...........................................................................................................................133
8.1.2 Modes of Operation ........................................................................................................134
8.1.3 Block Diagram ................................................................................................................135
External Signal Description ..........................................................................................................135
8.2.1 EXTAL — External Reference Clock / Oscillator Input ................................................135
8.2.2 XTAL — Oscillator Output ............................................................................................135
8.2.3 External Clock Connections ...........................................................................................136
8.2.4 External Crystal/Resonator Connections ........................................................................136
Register Definition ........................................................................................................................137
8.3.1 ICG Control Register 1 (ICGC1) ....................................................................................137
8.3.2 ICG Control Register 2 (ICGC2) ....................................................................................139
8.3.3 ICG Status Register 1 (ICGS1) .......................................................................................140
8.3.4 ICG Status Register 2 (ICGS2) .......................................................................................141
8.3.5 ICG Filter Registers (ICGFLTU, ICGFLTL) ..................................................................141
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
Freescale Semiconductor
Section Number
8.4
8.5
Title
Page
8.3.6 ICG Trim Register (ICGTRM) .......................................................................................142
Functional Description ..................................................................................................................142
8.4.1 Off Mode (Off) ................................................................................................................143
8.4.2 Self-Clocked Mode (SCM) .............................................................................................143
8.4.3 FLL Engaged, Internal Clock (FEI) Mode .....................................................................144
8.4.4 FLL Engaged Internal Unlocked ....................................................................................145
8.4.5 FLL Engaged Internal Locked ........................................................................................145
8.4.6 FLL Bypassed, External Clock (FBE) Mode ..................................................................145
8.4.7 FLL Engaged, External Clock (FEE) Mode ...................................................................145
8.4.8 FLL Lock and Loss-of-Lock Detection ..........................................................................146
8.4.9 FLL Loss-of-Clock Detection .........................................................................................147
8.4.10 Clock Mode Requirements .............................................................................................148
8.4.11 Fixed Frequency Clock ...................................................................................................149
8.4.12 High Gain Oscillator .......................................................................................................149
Initialization/Application Information ..........................................................................................149
8.5.1 Introduction .....................................................................................................................149
8.5.2 Example #1: External Crystal = 32 kHz, Bus Frequency = 4.19 MHz ...........................151
8.5.3 Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz ..............................153
8.5.4 Example #3: No External Crystal Connection, 5.4 MHz Bus Frequency ......................155
8.5.5 Example #4: Internal Clock Generator Trim ..................................................................157
Chapter 9
Keyboard Interrupt (S08KBIV1)
9.1
9.2
9.3
9.4
9.5
Introduction ...................................................................................................................................159
Keyboard Pin Sharing ....................................................................................................................159
Features .........................................................................................................................................159
9.3.1 KBI Block Diagram ........................................................................................................161
Register Definition ........................................................................................................................161
9.4.1 KBI Status and Control Register (KBISC) .....................................................................162
9.4.2 KBI Pin Enable Register (KBIPE) ..................................................................................163
Functional Description ..................................................................................................................163
9.5.1 Pin Enables ......................................................................................................................163
9.5.2 Edge and Level Sensitivity ..............................................................................................163
9.5.3 KBI Interrupt Controls ....................................................................................................164
Chapter 10
Timer/PWM (S08TPMV3)
10.1 Introduction ...................................................................................................................................165
10.2 Features .........................................................................................................................................165
10.3 TPMV3 Differences from Previous Versions ................................................................................168
10.3.1 Migrating from TPMV1 ..................................................................................................170
10.3.2 Features ...........................................................................................................................171
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
13
Section Number
10.4
10.5
10.6
10.7
10.8
Title
Page
10.3.3 Modes of Operation ........................................................................................................171
10.3.4 Block Diagram ................................................................................................................172
Signal Description .........................................................................................................................174
10.4.1 Detailed Signal Descriptions ...........................................................................................174
Register Definition ........................................................................................................................178
10.5.1 TPM Status and Control Register (TPMxSC) ................................................................178
10.5.2 TPM-Counter Registers (TPMxCNTH:TPMxCNTL) ....................................................179
10.5.3 TPM Counter Modulo Registers (TPMxMODH:TPMxMODL) ....................................180
10.5.4 TPM Channel n Status and Control Register (TPMxCnSC) ..........................................181
10.5.5 TPM Channel Value Registers (TPMxCnVH:TPMxCnVL) ..........................................183
Functional Description ..................................................................................................................184
10.6.1 Counter ............................................................................................................................185
10.6.2 Channel Mode Selection .................................................................................................187
Reset Overview .............................................................................................................................190
10.7.1 General ............................................................................................................................190
10.7.2 Description of Reset Operation .......................................................................................190
Interrupts .......................................................................................................................................190
10.8.1 General ............................................................................................................................190
10.8.2 Description of Interrupt Operation ..................................................................................191
Chapter 11
Serial Communications Interface (S08SCIV4)
11.1 Introduction ...................................................................................................................................193
11.1.1 Features ...........................................................................................................................195
11.1.2 Modes of Operation ........................................................................................................195
11.1.3 Block Diagram ................................................................................................................196
11.2 Register Definition ........................................................................................................................198
11.2.1 SCI Baud Rate Registers (SCIxBDH, SCIxBDL) ..........................................................198
11.2.2 SCI Control Register 1 (SCIxC1) ...................................................................................199
11.2.3 SCI Control Register 2 (SCIxC2) ...................................................................................200
11.2.4 SCI Status Register 1 (SCIxS1) ......................................................................................201
11.2.5 SCI Status Register 2 (SCIxS2) ......................................................................................203
11.2.6 SCI Control Register 3 (SCIxC3) ...................................................................................204
11.2.7 SCI Data Register (SCIxD) .............................................................................................205
11.3 Functional Description ..................................................................................................................205
11.3.1 Baud Rate Generation .....................................................................................................205
11.3.2 Transmitter Functional Description ................................................................................206
11.3.3 Receiver Functional Description .....................................................................................207
11.3.4 Interrupts and Status Flags ..............................................................................................209
11.3.5 Additional SCI Functions ...............................................................................................210
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
Freescale Semiconductor
Section Number
Title
Page
Chapter 12
Serial Peripheral Interface (S08SPIV3)
12.1 Introduction ...................................................................................................................................213
12.1.1 Features ...........................................................................................................................215
12.1.2 Block Diagrams ..............................................................................................................215
12.1.3 SPI Baud Rate Generation ..............................................................................................217
12.2 External Signal Description ..........................................................................................................218
12.2.1 SPSCK — SPI Serial Clock ............................................................................................218
12.2.2 MOSI — Master Data Out, Slave Data In ......................................................................218
12.2.3 MISO — Master Data In, Slave Data Out ......................................................................218
12.2.4 SS — Slave Select ...........................................................................................................218
12.3 Modes of Operation .......................................................................................................................219
12.3.1 SPI in Stop Modes ..........................................................................................................219
12.4 Register Definition ........................................................................................................................219
12.4.1 SPI Control Register 1 (SPI1C1) ....................................................................................219
12.4.2 SPI Control Register 2 (SPI1C2) ....................................................................................220
12.4.3 SPI Baud Rate Register (SPI1BR) ..................................................................................221
12.4.4 SPI Status Register (SPI1S) ............................................................................................222
12.4.5 SPI Data Register (SPI1D) ..............................................................................................223
12.5 Functional Description ..................................................................................................................224
12.5.1 SPI Clock Formats ..........................................................................................................224
12.5.2 SPI Interrupts ..................................................................................................................227
12.5.3 Mode Fault Detection .....................................................................................................227
Chapter 13
Inter-Integrated Circuit (S08IICV2)
13.1 Introduction ...................................................................................................................................229
13.1.1 Features ...........................................................................................................................231
13.1.2 Modes of Operation ........................................................................................................231
13.1.3 Block Diagram ................................................................................................................232
13.2 External Signal Description ..........................................................................................................232
13.2.1 SCL — Serial Clock Line ...............................................................................................232
13.2.2 SDA — Serial Data Line ................................................................................................232
13.3 Register Definition ........................................................................................................................232
13.3.1 IIC Address Register (IIC1A) .........................................................................................233
13.3.2 IIC Frequency Divider Register (IIC1F) .........................................................................233
13.3.3 IIC Control Register (IIC1C1) ........................................................................................236
13.3.4 IIC Status Register (IIC1S) .............................................................................................237
13.3.5 IIC Data I/O Register (IIC1D) ........................................................................................238
13.3.6 IIC Control Register 2 (IIC1C2) .....................................................................................238
13.4 Functional Description ..................................................................................................................239
13.4.1 IIC Protocol .....................................................................................................................239
MC9S08AC16 Series Data Sheet, Rev. 0
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Section Number
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13.4.2 10-bit Address .................................................................................................................243
13.4.3 General Call Address ......................................................................................................244
13.5 Resets ............................................................................................................................................244
13.6 Interrupts .......................................................................................................................................244
13.6.1 Byte Transfer Interrupt ....................................................................................................244
13.6.2 Address Detect Interrupt .................................................................................................244
13.6.3 Arbitration Lost Interrupt ................................................................................................244
13.7 Initialization/Application Information ..........................................................................................246
Chapter 14
Analog-to-Digital Converter (S08ADC10V1)
14.1 Overview .......................................................................................................................................249
14.2 Channel Assignments ....................................................................................................................249
14.2.1 Alternate Clock ...............................................................................................................250
14.2.2 Hardware Trigger ............................................................................................................250
14.2.3 Temperature Sensor ........................................................................................................252
14.2.4 Features ...........................................................................................................................253
14.2.5 Block Diagram ................................................................................................................253
14.3 External Signal Description ..........................................................................................................254
14.3.1 Analog Power (VDDAD) ..................................................................................................255
14.3.2 Analog Ground (VSSAD) .................................................................................................255
14.3.3 Voltage Reference High (VREFH) ...................................................................................255
14.3.4 Voltage Reference Low (VREFL) .....................................................................................255
14.3.5 Analog Channel Inputs (ADx) ........................................................................................255
14.4 Register Definition ........................................................................................................................255
14.4.1 Status and Control Register 1 (ADC1SC1) ....................................................................255
14.4.2 Status and Control Register 2 (ADC1SC2) ....................................................................257
14.4.3 Data Result High Register (ADC1RH) ...........................................................................258
14.4.4 Data Result Low Register (ADC1RL) ............................................................................258
14.4.5 Compare Value High Register (ADC1CVH) ..................................................................259
14.4.6 Compare Value Low Register (ADC1CVL) ...................................................................259
14.4.7 Configuration Register (ADC1CFG) ..............................................................................259
14.4.8 Pin Control 1 Register (APCTL1) ..................................................................................261
14.4.9 Pin Control 2 Register (APCTL2) ..................................................................................262
14.4.10Pin Control 3 Register (APCTL3) ..................................................................................263
14.5 Functional Description ..................................................................................................................264
14.5.1 Clock Select and Divide Control ....................................................................................264
14.5.2 Input Select and Pin Control ...........................................................................................265
14.5.3 Hardware Trigger ............................................................................................................265
14.5.4 Conversion Control .........................................................................................................265
14.5.5 Automatic Compare Function .........................................................................................268
14.5.6 MCU Wait Mode Operation ............................................................................................268
MC9S08AC16 Series Data Sheet, Rev. 0
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14.5.7 MCU Stop3 Mode Operation ..........................................................................................268
14.5.8 MCU Stop1 and Stop2 Mode Operation .........................................................................269
14.6 Initialization Information ..............................................................................................................269
14.6.1 ADC Module Initialization Example .............................................................................269
14.7 Application Information ................................................................................................................271
14.7.1 External Pins and Routing ..............................................................................................271
14.7.2 Sources of Error ..............................................................................................................273
Chapter 15
Development Support
15.1 Introduction ...................................................................................................................................277
15.1.1 Features ...........................................................................................................................278
15.2 Background Debug Controller (BDC) ..........................................................................................278
15.2.1 BKGD Pin Description ...................................................................................................279
15.2.2 Communication Details ..................................................................................................280
15.2.3 BDC Commands .............................................................................................................284
15.2.4 BDC Hardware Breakpoint .............................................................................................286
15.3 On-Chip Debug System (DBG) ....................................................................................................287
15.3.1 Comparators A and B ......................................................................................................287
15.3.2 Bus Capture Information and FIFO Operation ...............................................................287
15.3.3 Change-of-Flow Information ..........................................................................................288
15.3.4 Tag vs. Force Breakpoints and Triggers .........................................................................288
15.3.5 Trigger Modes .................................................................................................................289
15.3.6 Hardware Breakpoints ....................................................................................................291
15.4 Register Definition ........................................................................................................................291
15.4.1 BDC Registers and Control Bits .....................................................................................291
15.4.2 System Background Debug Force Reset Register (SBDFR) ..........................................293
15.4.3 DBG Registers and Control Bits .....................................................................................294
Appendix A
Electrical Characteristics and Timing Specifications
A.1
A.2
A.3
A.4
A.5
A.6
A.7
A.8
A.9
Introduction ....................................................................................................................................299
Parameter Classification.................................................................................................................299
Absolute Maximum Ratings...........................................................................................................299
Thermal Characteristics..................................................................................................................301
ESD Protection and Latch-Up Immunity .......................................................................................302
DC Characteristics..........................................................................................................................303
Supply Current Characteristics.......................................................................................................306
ADC Characteristics.......................................................................................................................309
Internal Clock Generation Module Characteristics ........................................................................312
A.9.1 ICG Frequency Specifications .........................................................................................313
A.10 AC Characteristics..........................................................................................................................316
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
17
Section Number
Title
Page
A.10.1 Control Timing ................................................................................................................316
A.10.2 Timer/PWM (TPM) Module Timing ...............................................................................317
A.11 SPI Characteristics .........................................................................................................................319
A.12 FLASH Specifications....................................................................................................................322
A.13 EMC Performance..........................................................................................................................323
Appendix B
Ordering Information and Mechanical Drawings
B.1 Ordering Information .....................................................................................................................325
B.2 Mechanical Drawings.....................................................................................................................326
MC9S08AC16 Series Data Sheet, Rev. 0
18
PRELIMINARY
Freescale Semiconductor
Chapter 1
Introduction
1.1
Overview
The MC9S08AC16 Series devices are members of the low-cost, high-performance HCS08 Family of 8-bit
microcontroller units (MCUs). All MCUs in the family use the enhanced HCS08 core and are available
with a variety of modules, memory sizes, memory types, and package types. Refer to Table 1-1 for
memory sizes and package types.
•
•
NOTE
The MC9S08AC16 and MC9S08AC8 devices are qualified for, and are
intended to be used in, consumer and industrial applications.
The S9S08AW16A and S9S08AW8A devices are qualified for, and are
intended to be used in, automotive applications.
Table 1-1 summarizes the feature set available in the MCUs.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
19
Chapter 1 Introduction
Table 1-1. Features by MCU and Package
Consumer and Industrial “AC” Devices
Feature
MC9S08AC16
MC9S08AC8
FLASH size (bytes)
16K
8K
RAM size (bytes)
1024
768
48
44
32
48
44
32
ADC channels
8
8
6
8
8
6
TPM1 channels
4
4
2
4
4
2
TPM2 channels
2
2
2
2
2
2
TPM3 channels
2
2
2
2
2
2
KBI pins
7
6
4
7
6
4
GPIO pins
38
34
22
38
34
22
Pin quantity
Consumer & Industrial
Qualified
yes
yes
Automotive Qualified
no
no
Automotive “AW” Devices
Feature
S9S08AW16A
S9S08AW8A
FLASH size (bytes)
16K
8K
RAM size (bytes)
1024
768
48
44
32
48
44
32
ADC channels
8
8
6
8
8
6
TPM1 channels
4
4
2
4
4
2
TPM2 channels
2
2
2
2
2
2
TPM3 channels
—
—
—
—
—
—
Pin quantity
1.2
KBI pins
7
6
4
7
6
4
GPIO pins
38
34
22
38
34
22
Consumer & Industrial
Qualified
no
no
Automotive Qualified
yes
yes
MCU Block Diagrams
The block diagram shows the structure of the MC9S08AC16 Series MCU.
MC9S08AC16 Series Data Sheet, Rev. 0
20
PRELIMINARY
Freescale Semiconductor
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 1 Introduction
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
21
Chapter 1 Introduction
Figure 1-1. MC9S08AC16 Block Diagram
Table 1-2 lists the functional versions of the on-chip modules.
Table 1-2. Versions of On-Chip Modules
Module
1.3
Version
Analog-to-Digital Converter
(ADC)
1
Internal Clock Generator
(ICG)
4
Inter-Integrated Circuit
(IIC)
2
Keyboard Interrupt
(KBI)
1
Serial Communications Interface
(SCI)
4
Serial Peripheral Interface
(SPI)
3
Timer Pulse-Width Modulator
(TPM)
3
Central Processing Unit
(CPU)
2
System Clock Distribution
TPMCLK
ICGERCLK
SYSTEM
CONTROL
LOGIC
RTI
FFE
TPM1
TPM2
IIC1
SCI1
SCI2
SPI1
RAM
FLASH
2
ICG
XCLK**
COP
ICGOUT
2
1 kHz
BUSCLK
ICGLCLK*
CPU
BDC
TPM3***
* ICGLCLK is the alternate BDC clock source for the MC9S08AC16 Series.
** XCLK is the fixed-frequency clock.
*** TPM3 is not available on S9S08AWxxA devices.
ADC1
ADC has min and max
frequency requirements.
See the Electricals appendix
and the ADC chapter.
FLASH has frequency
requirements for program
and erase operation.
See the Electricals
appendix.
Figure 1-2. System Clock Distribution Diagram
Some of the modules inside the MCU have clock source choices. Figure 1-2 shows a simplified clock
connection diagram. The ICG supplies the clock sources:
• ICGOUT is an output of the ICG module. It is one of the following:
— The external crystal oscillator
— An external clock source
MC9S08AC16 Series Data Sheet, Rev. 0
22
PRELIMINARY
Freescale Semiconductor
Chapter 1 Introduction
•
•
•
— The output of the digitally-controlled oscillator (DCO) in the frequency-locked loop
sub-module
— Control bits inside the ICG determine which source is connected.
FFE is a control signal generated inside the ICG. If the frequency of ICGOUT > 4 × the frequency
of ICGERCLK, this signal is a logic 1 and the fixed-frequency clock will be ICGERCLK/2.
Otherwise the fixed-frequency clock will be BUSCLK.
ICGLCLK — Development tools can select this internal self-clocked source (~ 8 MHz) to speed
up BDC communications in systems where the bus clock is slow.
ICGERCLK — External reference clock can be selected as the real-time interrupt clock source.
Can also be used as the ALTCLK input to the ADC module.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
23
Chapter 1 Introduction
MC9S08AC16 Series Data Sheet, Rev. 0
24
PRELIMINARY
Freescale Semiconductor
Chapter 2
Pins and Connections
2.1
Introduction
This chapter describes signals that connect to package pins. It includes a pinout diagram, a table of signal
properties, and detailed discussion of signals.
2.2
Device Pin Assignment
37 PTG4/KB1IP4
38 VREFH
39 VREFL
40 BKGD/MS
41 PTG5/XTAL
42 PTG6/EXTAL
43 VSS
44 PTC0/SCL1
45 PTC1/SDA1
46 PTC2/MCLK
47 PTC3/TxD2
48 PTC5/RxD2
Figure 2-1 shows the 48-pin QFN pin assignments for the MC9S08AC16 Series device.
PTC4 1
36 PTG3/KBIP3
IRQ/TPMCLK 2
35 PTD3/KBIP6/AD1P11
RESET 3
34 PTD2/KBIP5/AD1P10
PTF0/TPM1CH2 4
33 VSSAD
PTF1/TPM1CH3 5
32 VDDAD
PTF4/TPM2CH0 6
31 PTD1/AD1P9
48-Pin QFN
PTA2 24
25 PTA7
PTA1 23
PTE3/TPM1CH1 12
PTA0 22
26 PTB0/TPM3CH0/AD1P01
PTG2/KBIP2 21
PTE2/TPM1CH0 11
PTG1/KBIP1 20
27 PTB1/TPM3CH1/AD1P11
PTG0/KBIP0 19
PTE1/RxD1 10
VDD 18
28 PTB2/AD1P2
VSS 17
PTE0/TxD1 9
PTE7/SPSCK1 16
29 PTB3/AD1P3
PTE6/MOSI1 15
PTF6 8
PTE5/MISO1 14
30 PTD0/AD1P8
PTE4/SS1 13
PTF5/TPM2CH1 7
Figure 2-1. MC9S08AC16 Series in 48-Pin QFN Package1
1. TPM3 not available on the S9S08AWxxA.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
25
Chapter 2 Pins and Connections
34
44
43
PTC4 1
VREFH
VREFL
BKGD/MS
PTG5/XTAL
PTG6/EXTAL
VSS
PTC0/SCL1
PTC1/SDA1
PTC2/MCLK
PTC3/TxD2
PTC5/RxD2
Figure 2-2. shows the 44-pin LQFP pin assignments for the MC9S08AC16 Series device.
42
41
40
39
38
37
35
36
33 PTG3/KBIP3
IRQ/TPMCLK
2
32
PTD3/KBIP6/AD1P11
RESET
3
31
PTD2/KBIP5/AD1P10
PTF0/TPM1CH2
4
30
VSSAD
PTF1/TPM1CH3
5
29
VDDAD
28
PTD1/AD1P9
44-Pin LQFP
PTF4/TPM2CH0
6
PTF5/TPM2CH1
7
27
PTD0/AD1P8
PTE0/TxD1
8
26
PTB3/AD1P3
PTE1/RxD1
9
25
PTB2/AD1P2
PTE2/TPM1CH0
10
24
PTB1/TPM3CH1/AD1P1
1
1
PTE3/TPM1CH1 11
23 PTB0/TPM3CH0/AD1P0
13
14
15
16
17
18
19
20
21
PTA0
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
VDD
VSS
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTA1
22
12
Figure 2-2. MC9S08AC16 Series in 44-Pin LQFP Package1
1. TPM3 not available on the S9S08AWxxA.
MC9S08AC16 Series Data Sheet, Rev. 0
26
PRELIMINARY
Freescale Semiconductor
Chapter 2 Pins and Connections
PTC0/SCL1
VSS
PTG6/EXTAL
PTG5/XTAL
BKGD/MS
VREFL
VREFH
PTC1/SDA1
Figure 2-3. shows the 32-pin LQFP pin assignments for the MC9S08AC16 Series device.
31
30
29
28
27
26
25
32
IRQ/TPMCLK 1
24 PTD3/AD1P11/KBIP6
RESET
2
23
PTD2/AD1P10/KBIP5
PTF4/TPM2CH0
3
22
VSSAD
PTF5/TPM2CH1
4
21
VDDAD
PTE0/TxD1
5
20
PTB3/AD1P3
PTE1/RxD1
6
19
PTB2/AD1P2
PTE2/TPM1CH0
7
18
PTB1/TPM3CH1/AD1P11
PTE3/TPM1CH1
8
17
PTB0/TPM3CH0/AD1P01
PTE7/SPSCK1
14
15
16
PTG1/KBIP1
PTE6/MOSI1
13
PTG0/KBIP0
12
VDD
11
VSS
10
PTE5/MISO1
32-Pin LQFP
PTE4/SS1
9
Figure 2-3. MC9S08AC16 Series in 32-Pin LQFP Package1
1. TPM3 not available on the S9S08AWxxA.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
27
Chapter 2 Pins and Connections
Table 2-1. Pin Availability by Package Pin-Count
Pin Number
<-- Lowest
48
44
32
Port Pin
25
—
— PTA7
TPMCLK
26
23
17 PTB0
TPM3CH01 AD1P0
RESET
27
24
18 PTB1
TPM3CH11 AD1P1
TPM1CH2
28
25
19 PTB2
AD1P2
— PTF1
TPM1CH3
29
26
20 PTB3
AD1P3
6
3
PTF4
TPM2CH0
30
27
— PTD0
AD1P8
7
4
PTF5
TPM2CH1
31
28
— PTD1
AD1P9
32
29
21
VDDAD
VSSAD
Pin Number
<-- Lowest
48
44
32
Port Pin
1
1
— PTC4
2
2
1
3
3
2
4
4
— PTF0
5
5
6
7
Priority
--> Highest
Alt 1
Alt 2
IRQ
Priority
--> Highest
Alt 1
8
—
— PTF6
9
8
5
PTE0
TxD1
33
30
22
10
9
6
PTE1
RxD1
34
31
23 PTD2
AD1P10
11
10
7
PTE2
TPM1CH0
35
32
24 PTD3
AD1P11
TPM1CH1
36
33
— PTG3
SS1
37
—
— PTG4
Alt 2
KBIP5
KBIP6
KBIP3
12
11
8
PTE3
13
12
9
PTE4
14
13
10 PTE5
MISO1
38
34
25
15
14
11 PTE6
MOSI1
39
35
26
36
27 BKGD
MS
KBIP4
VREFH
VREFL
16
15
12 PTE7
SPSCK1
40
17
16
13
VSS
41
37
28 PTG5
XTAL
18
17
14
VDD
42
38
29 PTG6
EXTAL
19
18
15 PTG0
KBIP0
43
39
30
VSS
40
31 PTC0
SCL1
20
19
16 PTG1
KBIP1
44
21
20
— PTG2
KBIP2
45
41
32 PTC1
SDA1
22
21
— PTA0
46
42
— PTC2
MCLK
23
22
— PTA1
47
43
— PTC3
TxD2
— PTA2
48
44
— PTC5
RxD2
24
—
1
TPM3 not available on S9S08AWxxA.
Table 2-2. Pin Function Reference
Signal Function
Example(s)
Reference
Port Pins
PTAx, PTBx
Chapter 6, “Parallel Input/Output”
Serial peripheral interface
SS, MISO, MOSI, SPSCK
Chapter 12, “Serial Peripheral Interface (S08SPIV3)”
Keyboard interrupts
KBIPx
Chapter 9, “Keyboard Interrupt (S08KBIV1)”
Timer/PWM
TCLK, TPMCHx
Chapter 10, “Timer/PWM (S08TPMV3)”
Inter-integrated circuit
SCL, SDA
Chapter 13, “Inter-Integrated Circuit (S08IICV2)”
Serial communications interface
TxD, RxD
Chapter 11, “Serial Communications Interface (S08SCIV4)”
Oscillator/clocking
EXTAL, XTAL
Chapter 8, “Internal Clock Generator (S08ICGV4)”
Analog-to-digital
ADPx
Chapter 14, “Analog-to-Digital Converter (S08ADC10V1)”
Power/core
BKGD/MS, VDD, VSS
Chapter 2, “Pins and Connections”
Reset and interrupts
RESET, IRQ
Chapter 5, “Resets, Interrupts, and System Configuration”
MC9S08AC16 Series Data Sheet, Rev. 0
28
PRELIMINARY
Freescale Semiconductor
Chapter 2 Pins and Connections
2.3
Recommended System Connections
Figure 2-4 shows pin connections that are common to almost all MC9S08AC16 Series application
systems.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
29
Chapter 2 Pins and Connections
VREFH
CBYAD
0.1 μF
PTA0
VSSAD
VREFL
VDD
VDD
SYSTEM
POWER
+
5V
MC9S08AC16
VDDAD
CBLK +
10 μF
PORT
A
CBY
0.1 μF
PTA1
PTA2
PTA7
PTB0/AD1P0/TPM3CH0 NOTE 4
VSS (x2)
PORT
B
PTB1/AD1P1/TPM3CH1 NOTE 4
PTB2/AD1P2
PTB3/AD1P3
NOTE 1
RF
C1
X1
RS
PTC0/SCL1
XTAL
NOTE 2
C2
EXTAL
NOTE 2
PTC1/SDA1
PORT
C
PTC2/MCLK
I/O AND
PTC3/TxD2
PERIPHERAL
PTC4
BACKGROUND HEADER
PTC5/RxD2
INTERFACE TO
APPLICATION
VDD
BKGD/MS
PTD0/AD1P8
PORT
D
VDD
OPTIONAL
MANUAL
RESET
RESET
NOTE 3
VDD
PTE0/TxD1
PTE1/RxD1
PTE2/TPM1CH0
4.7 kΩ–
10 kΩ
ASYNCHRONOUS
INTERRUPT
INPUT
PTD2/AD1P10/KBIP5
PTD3/AD1P11/KBIP6
4.7 kΩ–10 kΩ
0.1 μF
SYSTEM
PTD1/AD1P9
0.1 μF
TPMCLK/IRQ
NOTE 3
PORT
E
PTE3/TPM1CH1
PTE4/SS1
PTE5/MISO1
PTE6/MOSI1
PTE7/SPSCK1
PTG0/KBIP0
PTG1/KBIP1
PTG2/KBIP2
PTG3/KBIP3
PTF0/TPM1CH2
PORT
G
PTG4/KBIP4
PTG5/XTAL
PORT
F
PTF1/TPM1CH3
PTF4/TPM2CH0
PTF5/TPM2CH1
PTF6
PTG6/EXTAL
NOTES:
1. Not required if using the internal clock option.
2. XTAL and EXTAL are PTG5 and PTG6 respectively.
3. RC filters on RESET and IRQ are recommended for EMC-sensitive applications.
4. TPM3 is not available on S9S08AWxxA.
Figure 2-4. Basic System Connections
MC9S08AC16 Series Data Sheet, Rev. 0
30
PRELIMINARY
Freescale Semiconductor
Chapter 2 Pins and Connections
2.3.1
Power (VDD, 2 x VSS, VDDAD, VSSAD)
VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all
I/O buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides regulated
lower-voltage source to the CPU and other internal circuitry of the MCU.
Typically, application systems have two separate capacitors across the power pins. In this case, there
should be a bulk electrolytic capacitor, such as a 10-μF tantalum capacitor, to provide bulk charge storage
for the overall system and a 0.1-μF ceramic bypass capacitor located as near to the paired VDD and VSS
power pins as practical to suppress high-frequency noise. The MC9S08AC16 has a second VSS pin. This
pin should be connected to the system ground plane or to the primary VSS pin through a low-impedance
connection.
VDDAD and VSSAD are the analog power supply pins for the MCU. This voltage source supplies power to
the ADC module. A 0.1-μF ceramic bypass capacitor should be located as near to the analog power pins
as practical to suppress high-frequency noise.
2.3.2
Oscillator (XTAL, EXTAL)
Out of reset the MCU uses an internally generated clock (self-clocked mode — fSelf_reset) equivalent to
about 8-MHz crystal rate. This frequency source is used during reset startup and can be enabled as the
clock source for stop recovery to avoid the need for a long crystal startup delay. This MCU also contains
a trimmable internal clock generator (ICG) module that can be used to run the MCU. For more information
on the ICG, see the Chapter 8, “Internal Clock Generator (S08ICGV4).”
The oscillator in this MCU is a Pierce oscillator that can accommodate a crystal or ceramic resonator in
either of two frequency ranges selected by the RANGE bit in the ICGC1 register. Rather than a crystal or
ceramic resonator, an external oscillator can be connected to the EXTAL input pin.
Refer to Figure 2-4 for the following discussion. RS (when used) and RF should be low-inductance
resistors such as carbon composition resistors. Wire-wound resistors, and some metal film resistors, have
too much inductance. C1 and C2 normally should be high-quality ceramic capacitors that are specifically
designed for high-frequency applications.
RF is used to provide a bias path to keep the EXTAL input in its linear range during crystal startup and its
value is not generally critical. Typical systems use 1 MΩ to 10 MΩ. Higher values are sensitive to humidity
and lower values reduce gain and (in extreme cases) could prevent startup.
C1 and C2 are typically in the 5-pF to 25-pF range and are chosen to match the requirements of a specific
crystal or resonator. Be sure to take into account printed circuit board (PCB) capacitance and MCU pin
capacitance when sizing C1 and C2. The crystal manufacturer typically specifies a load capacitance which
is the series combination of C1 and C2 which are usually the same size. As a first-order approximation,
use 10 pF as an estimate of combined pin and PCB capacitance for each oscillator pin (EXTAL and
XTAL).
2.3.3
RESET
RESET is a dedicated pin with a pullup device built in. It has input hysteresis, a high current output driver,
and no output slew rate control. Internal power-on reset and low-voltage reset circuitry typically make
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
31
Chapter 2 Pins and Connections
external reset circuitry unnecessary. This pin is normally connected to the standard 6-pin background
debug connector so a development system can directly reset the MCU system. If desired, a manual external
reset can be added by supplying a simple switch to ground (pull reset pin low to force a reset).
Whenever any reset is initiated (whether from an external signal or from an internal system), the reset pin
is driven low for approximately 34 bus cycles. The reset circuitry decodes the cause of reset and records it
by setting a corresponding bit in the system control reset status register (SRS).
In EMC-sensitive applications, an external RC filter is recommended on the reset pin. See Figure 2-4 for
an example.
2.3.4
Background/Mode Select (BKGD/MS)
While in reset, the BKGD/MS pin functions as a mode select pin. Immediately after reset rises the pin
functions as the background pin and can be used for background debug communication. While functioning
as a background/mode select pin, the pin includes an internal pullup device, input hysteresis, a standard
output driver, and no output slew rate control.
If nothing is connected to this pin, the MCU will enter normal operating mode at the rising edge of reset.
If a debug system is connected to the 6-pin standard background debug header, it can hold BKGD/MS low
during the rising edge of reset which forces the MCU to active background mode.
The BKGD pin is used primarily for background debug controller (BDC) communications using a custom
protocol that uses 16 clock cycles of the target MCU’s BDC clock per bit time. The target MCU’s BDC
clock could be as fast as the bus clock rate, so there should never be any significant capacitance connected
to the BKGD/MS pin that could interfere with background serial communications.
Although the BKGD pin is a pseudo open-drain pin, the background debug communication protocol
provides brief, actively driven, high speedup pulses to ensure fast rise times. Small capacitances from
cables and the absolute value of the internal pullup device play almost no role in determining rise and fall
times on the BKGD pin.
2.3.5
ADC Reference Pins (VREFH, VREFL)
The VREFH and VREFL pins are the voltage reference high and voltage reference low inputs respectively
for the ADC module.
2.3.6
External Interrupt Pin (IRQ)
The IRQ pin is the input source for the IRQ interrupt and is also the input for the BIH and BIL instructions.
If the IRQ function is not enabled, this pin does not perform any function.
In EMC-sensitive applications, an external RC filter is recommended on the IRQ pin. See Figure 2-4 for
an example.
MC9S08AC16 Series Data Sheet, Rev. 0
32
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Chapter 2 Pins and Connections
2.3.7
General-Purpose I/O and Peripheral Ports
The remaining pins are shared among general-purpose I/O and on-chip peripheral functions such as timers
and serial I/O systems. Immediately after reset, all of these pins are configured as high-impedance
general-purpose inputs with internal pullup devices disabled.
NOTE
To avoid extra current drain from floating input pins, the reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unused pins to outputs so the pins do not
float.
For information about controlling these pins as general-purpose I/O pins, see Chapter 6, “Parallel
Input/Output.” For information about how and when on-chip peripheral systems use these pins, refer to the
appropriate chapter from Table 2-2.
When an on-chip peripheral system is controlling a pin, data direction control bits still determine what is
read from port data registers even though the peripheral module controls the pin direction by controlling
the enable for the pin’s output buffer. See the Chapter 6, “Parallel Input/Output” chapter for more details.
Pullup enable bits for each input pin control whether on-chip pullup devices are enabled whenever the pin
is acting as an input even if it is being controlled by an on-chip peripheral module. When the PTD3, PTD2,
and PTG4 pins are controlled by the KBI module and are configured for rising-edge/high-level sensitivity,
the pullup enable control bits enable pulldown devices rather than pullup devices. Similarly, when IRQ is
configured as the IRQ input and is set to detect rising edges, the pullup enable control bit enables a
pulldown device rather than a pullup device.
NOTE
When an alternative function is first enabled it is possible to get a spurious
edge to the module, user software should clear out any associated flags
before interrupts are enabled. Table 2-1 illustrates the priority if multiple
modules are enabled. The highest priority module will have control over the
pin. Selecting a higher priority pin function with a lower priority function
already enabled can cause spurious edges to the lower priority module. It is
recommended that all modules that share a pin be disabled before enabling
another module.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
33
Chapter 2 Pins and Connections
MC9S08AC16 Series Data Sheet, Rev. 0
34
PRELIMINARY
Freescale Semiconductor
Chapter 3
Modes of Operation
3.1
Introduction
The operating modes of the MC9S08AC16 Series are described in this chapter. Entry into each mode, exit
from each mode, and functionality while in each of the modes are described.
3.2
•
•
•
3.3
Features
Active background mode for code development
Wait mode:
— CPU shuts down to conserve power
— System clocks running
— Full voltage regulation maintained
Stop modes:
— System clocks stopped; voltage regulator in standby
— Stop2 — Partial power down of internal circuits, RAM contents retained
— Stop3 — All internal circuits powered for fast recovery
Run Mode
This is the normal operating mode for the MC9S08AC16 Series. This mode is selected when the
BKGD/MS pin is high at the rising edge of reset. In this mode, the CPU executes code from internal
memory with execution beginning at the address fetched from memory at 0xFFFE:0xFFFF after reset.
3.4
Active Background Mode
The active background mode functions are managed through the background debug controller (BDC) in
the HCS08 core. The BDC, together with the on-chip debug module (DBG), provide the means for
analyzing MCU operation during software development.
Active background mode is entered in any of five ways:
• When the BKGD/MS pin is low at the rising edge of reset
• When a BACKGROUND command is received through the BKGD pin
• When a BGND instruction is executed
• When encountering a BDC breakpoint
• When encountering a DBG breakpoint
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
35
Chapter 3 Modes of Operation
After entering active background mode, the CPU is held in a suspended state waiting for serial background
commands rather than executing instructions from the user’s application program.
Background commands are of two types:
• Non-intrusive commands, defined as commands that can be issued while the user program is
running. Non-intrusive commands can be issued through the BKGD pin while the MCU is in run
mode; non-intrusive commands can also be executed when the MCU is in the active background
mode. Non-intrusive commands include:
— Memory access commands
— Memory-access-with-status commands
— BDC register access commands
— The BACKGROUND command
• Active background commands, which can only be executed while the MCU is in active background
mode. Active background commands include commands to:
— Read or write CPU registers
— Trace one user program instruction at a time
— Leave active background mode to return to the user’s application program (GO)
The active background mode is used to program a bootloader or user application program into the FLASH
program memory before the MCU is operated in run mode for the first time. When the MC9S08AC16
Series is shipped from the Freescale Semiconductor factory, the FLASH program memory is erased by
default unless specifically noted so there is no program that could be executed in run mode until the
FLASH memory is initially programmed. The active background mode can also be used to erase and
reprogram the FLASH memory after it has been previously programmed.
For additional information about the active background mode, refer to Chapter 15, “Development
Support.”
3.5
Wait Mode
Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT instruction, the CPU
enters a low-power state in which it is not clocked. The I bit in CCR is cleared when the CPU enters the
wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits the wait mode and
resumes processing, beginning with the stacking operations leading to the interrupt service routine.
While the MCU is in wait mode, there are some restrictions on which background debug commands can
be used. Only the BACKGROUND command and memory-access-with-status commands are available
when the MCU is in wait mode. The memory-access-with-status commands do not allow memory access,
but they report an error indicating that the MCU is in either stop or wait mode. The BACKGROUND
command can be used to wake the MCU from wait mode and enter active background mode.
3.6
Stop Modes
One of two stop modes is entered upon execution of a STOP instruction when the STOPE bit in the system
option register is set. In both stop modes, all internal clocks are halted. If the STOPE bit is not set when
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PRELIMINARY
Freescale Semiconductor
Chapter 3 Modes of Operation
the CPU executes a STOP instruction, the MCU will not enter either of the stop modes and an illegal
opcode reset is forced. The stop modes are selected by setting the appropriate bits in SPMSC2.
HCS08 devices that are designed for low voltage operation (1.8V to 3.6V) also include stop1 mode. The
MC9S08AC16 Series family of devices does not include stop1 mode.
Table 3-1 summarizes the behavior of the MCU in each of the stop modes.
Table 3-1. Stop Mode Behavior
1
Mode
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ADC
Regulator
I/O Pins
RTI
Stop2
1
Off
Standby
Off
Disabled
Standby
States
held
Optionally on
Stop3
0
Standby
Standby
Off1
Optionally on
Standby
States
held
Optionally on
Crystal oscillator can be configured to run in stop3. Please see the ICG registers.
3.6.1
Stop2 Mode
The stop2 mode provides very low standby power consumption and maintains the contents of RAM and
the current state of all of the I/O pins. To enter stop2, the user must execute a STOP instruction with stop2
selected (PPDC = 1) and stop mode enabled (STOPE = 1). In addition, the LVD must not be enabled to
operate in stop (LVDSE = LVDE = 1). If the LVD is enabled in stop, then the MCU enters stop3 upon the
execution of the STOP instruction regardless of the state of PPDC.
Before entering stop2 mode, the user must save the contents of the I/O port registers, as well as any other
memory-mapped registers which they want to restore after exit of stop2, to locations in RAM. Upon exit
of stop2, these values can be restored by user software before pin latches are opened.
When the MCU is in stop2 mode, all internal circuits that are powered from the voltage regulator are turned
off, except for the RAM. The voltage regulator is in a low-power standby state, as is the ADC. Upon entry
into stop2, the states of the I/O pins are latched. The states are held while in stop2 mode and after exiting
stop2 mode until a logic 1 is written to PPDACK in SPMSC2.
Exit from stop2 is done by asserting either of the wake-up pins: RESET or IRQ/TPMCLK, or by an RTI
interrupt. IRQ/TPMCLK is always an active low input when the MCU is in stop2, regardless of how it was
configured before entering stop2.
Upon wake-up from stop2 mode, the MCU will start up as from a power-on reset (POR) except pin states
remain latched. The CPU will take the reset vector. The system and all peripherals will be in their default
reset states and must be initialized.
After waking up from stop2, the PPDF bit in SPMSC2 is set. This flag may be used to direct user code to
go to a stop2 recovery routine. PPDF remains set and the I/O pin states remain latched until a logic 1 is
written to PPDACK in SPMSC2.
To maintain I/O state for pins that were configured as general-purpose I/O, the user must restore the
contents of the I/O port registers, which have been saved in RAM, to the port registers before writing to
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
37
Chapter 3 Modes of Operation
the PPDACK bit. If the port registers are not restored from RAM before writing to PPDACK, then the
register bits will assume their reset states when the I/O pin latches are opened and the I/O pins will switch
to their reset states.
For pins that were configured as peripheral I/O, the user must reconfigure the peripheral module that
interfaces to the pin before writing to the PPDACK bit. If the peripheral module is not enabled before
writing to PPDACK, the pins will be controlled by their associated port control registers when the I/O
latches are opened.
3.6.2
Stop3 Mode
To enter stop3, the user must execute a STOP instruction with stop3 selected (PPDC = 0) and stop mode
enabled (STOPE = 1). Upon entering the stop3 mode, all of the clocks in the MCU, including the oscillator
itself, are halted. The ICG enters its standby state, as does the voltage regulator and the ADC. The states
of all of the internal registers and logic, as well as the RAM content, are maintained. The I/O pin states are
not latched at the pin as in stop2. Instead they are maintained by virtue of the states of the internal logic
driving the pins being maintained.
Exit from stop3 is done by asserting RESET or by an interrupt from one of the following sources: the
real-time interrupt (RTI), LVD system, ADC, IRQ, KBI, or SCI.
If stop3 is exited by means of the RESET pin, then the MCU will be reset and operation will resume after
taking the reset vector. Exit by means of an asynchronous interrupt or the real-time interrupt will result in
the MCU taking the appropriate interrupt vector.
A separate self-clocked source (≈1 kHz) for the real-time interrupt allows a wakeup from stop2 or stop3
mode with no external components. When RTIS2:RTIS1:RTIS0 = 0:0:0, the real-time interrupt function
and this 1-kHz source are disabled. Power consumption is lower when the 1-kHz source is disabled, but in
that case the real-time interrupt cannot wake the MCU from stop.
3.6.3
Active BDM Enabled in Stop Mode
Entry into the active background mode from run mode is enabled if the ENBDM bit in BDCSCR is set.
This register is described in Chapter 15, “Development Support” of this data sheet. If ENBDM is set when
the CPU executes a STOP instruction, the system clocks to the background debug logic remain active when
the MCU enters stop mode so background debug communication is still possible. In addition, the voltage
regulator does not enter its low-power standby state but maintains full internal regulation. If the user
attempts to enter stop2 with ENBDM set, the MCU will instead enter stop3.
Most background commands are not available in stop mode. The memory-access-with-status commands
do not allow memory access, but they report an error indicating that the MCU is in either stop or wait
mode. The BACKGROUND command can be used to wake the MCU from stop and enter active
background mode if the ENBDM bit is set. After entering background debug mode, all background
commands are available. Table 3-2 summarizes the behavior of the MCU in stop when entry into the
background debug mode is enabled.
MC9S08AC16 Series Data Sheet, Rev. 0
38
PRELIMINARY
Freescale Semiconductor
Chapter 3 Modes of Operation
Table 3-2. BDM Enabled Stop Mode Behavior
Mode
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ADC
Regulator
I/O Pins
RTI
Stop3
0
Standby
Standby
Active
Optionally on
Active
States
held
Optionally on
3.6.4
LVD Enabled in Stop Mode
The LVD system is capable of generating either an interrupt or a reset when the supply voltage drops below
the LVD voltage. If the LVD is enabled in stop by setting the LVDE and the LVDSE bits, then the voltage
regulator remains active during stop mode. If the user attempts to enter stop2 with the LVD enabled for
stop, the MCU will instead enter stop3. Table 3-3 summarizes the behavior of the MCU in stop when the
LVD is enabled.
Table 3-3. LVD Enabled Stop Mode Behavior
Mode
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ADC
Regulator
I/O Pins
RTI
Stop3
0
Standby
Standby
Off
Optionally on
Active
States
held
Optionally on
3.6.5
On-Chip Peripheral Modules in Stop Modes
When the MCU enters any stop mode, system clocks to the internal peripheral modules are stopped. Even
in the exception case (ENBDM = 1), where clocks are kept alive to the background debug logic, clocks to
the peripheral systems are halted to reduce power consumption. Refer to Section 3.6.2, “Stop3 Mode” for
specific information on system behavior in stop modes.
I/O Pins
• All I/O pin states remain unchanged when the MCU enters stop3 mode.
• If the MCU is configured to go into stop2 mode, all I/O pins states are latched before entering stop.
Memory
• All RAM and register contents are preserved while the MCU is in stop3 mode.
• All registers will be reset upon wake-up from stop2, but the contents of RAM are preserved and
pin states remain latched until the PPDACK bit is written. The user may save any memory-mapped
register data into RAM before entering stop2 and restore the data upon exit from stop2.
• The contents of the FLASH memory are non-volatile and are preserved in any of the stop modes.
ICG — In stop3 mode, the ICG enters its low-power standby state. The oscillator may be kept running
when the ICG is in standby by setting OSCSTEN. In stop2 mode, the ICG is turned off. The oscillator
cannot be kept running in stop2 even if OSCSTEN is set. If the MCU is configured to go into stop2 mode,
the ICG will be reset upon wake-up from stop and must be reinitialized.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
39
Chapter 3 Modes of Operation
TPM — When the MCU enters stop mode, the clock to the TPM1 and TPM2 modules stop. The modules
halt operation. If the MCU is configured to go into stop2 mode, the TPM modules will be reset upon
wake-up from stop and must be reinitialized.
ADC — When the MCU enters stop mode, the ADC will enter a low-power standby state unless the
asynchronous clock source, ADACK, is enabled. Conversions can occur in stop3 if ADACK is enabled. If
the MCU is configured to go into stop2 mode, the ADC will be reset upon wake-up from stop and must be
re-initialized.
KBI — During stop3, the KBI pins that are enabled continue to function as interrupt sources that are
capable of waking the MCU from stop3. The KBI is disabled in stop2 and must be reinitialized after
waking up.
SCI — When the MCU enters stop mode, the clocks to the SCI1 and SCI2 modules stop. The modules
halt operation. If the MCU is configured to go into stop2 mode, the SCI modules will be reset upon
wake-up from stop and must be reinitialized.
SPI — When the MCU enters stop mode, the clocks to the SPI module stop. The module halts operation.
If the MCU is configured to go into stop2 mode, the SPI module will be reset upon wake-up from stop and
must be reinitialized.
IIC — When the MCU enters stop mode, the clocks to the IIC module stops. The module halts operation.
If the MCU is configured to go into stop2 mode, the IIC module will be reset upon wake-up from stop and
must be reinitialized.
Voltage Regulator — The voltage regulator enters a low-power standby state when the MCU enters either
of the stop modes unless the LVD is enabled in stop mode or BDM is enabled.
MC9S08AC16 Series Data Sheet, Rev. 0
40
PRELIMINARY
Freescale Semiconductor
Chapter 4
Memory
4.1
MC9S08AC16 Series Memory Map
Figure 4-1 shows the memory maps for the MC9S08AC16 Series MCUs. On-chip memory in the
MC9S08AC16 Series of MCU consists of RAM, FLASH program memory for nonvolatile data storage,
plus I/O and control/status registers. The registers are divided into three groups:
• Direct-page registers (0x0000 through 0x006F)
• High-page registers (0x1800 through 0x185F)
• Nonvolatile registers (0xFFB0 through 0xFFBF)
0x0000
0x006F
0x0070
0x046F
0x0470
0x0000
0x006F
0x0070
0x036F
0x0370
0x046F
0x0470
DIRECT PAGE REGISTERS
RAM
1024 BYTES
UNIMPLEMENTED
DIRECT PAGE REGISTERS
RAM
768 BYTES
RESERVED — 256 BYTES
UNIMPLEMENTED
5008 BYTES
5008 BYTES
0x17FF
0x1800
0x17FF
0x1800
HIGH PAGE REGISTERS
HIGH PAGE REGISTERS
0x185F
0x1860
0x185F
0x1860
UNIMPLEMENTED
UNIMPLEMENTED
42,912 BYTES
42,912 BYTES
0xBFFF
0xC000
0xBFFF
0xC000
RESERVED
8192 BYTES
FLASH
0xDFFF
0xE000
16,384 BYTES
FLASH
8192 BYTES
0xFFFF
0xFFFF
MC9S08AC8 and S9S08AW8A
MC9S08AC16 and S9S08AW16A
Figure 4-1. MC9S08AC16 Series Memory Maps
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
41
Chapter 4 Memory
4.1.1
Reset and Interrupt Vector Assignments
Figure 4-1 shows address assignments for reset and interrupt vectors. The vector names shown in this table
are the labels used in the Freescale-provided equate file for the MC9S08AC16 Series. For more details
about resets, interrupts, interrupt priority, and local interrupt mask controls, refer to Chapter 5, “Resets,
Interrupts, and System Configuration.”
Table 4-1. Reset and Interrupt Vectors
Address (High/Low)
Vector
Vector Name
0xFFC0:FFC1 through 0xFFC4:FFC5
Unused Vector Space
(available for user program)
—
1
0xFFC6:FFC
TPM3 overflow
1
Vtpm3ch1
1
TPM3 channel 1
0xFFC8:FFC9
Vtpm3ovf
1
0xFFCA:FFCB
TPM3 channel 0
Vtpm3ch0
0xFFCC:FFCD
RTI
Vrti
0xFFCE:FFCF
IIC1
Viic1
0xFFD0:FFD1
ADC1 Conversion
Vadc1
0xFFD2:FFD3
KBI
Vkeyboard1
0xFFD4:FFD5
SCI2 Transmit
Vsci2tx
0xFFD6:FFD7
SCI2 Receive
Vsci2rx
0xFFD8:FFD9
SCI2 Error
Vsci2err
0xFFDA:FFDB
SCI1 Transmit
Vsci1tx
0xFFDC:FFDD
SCI1 Receive
Vsci1rx
0xFFDE:FFDF
SCI1 Error
Vsci1err
0xFFE0:FFE1
SPI1
Vspi1
0xFFE2:FFE3
TPM2 Overflow
Vtpm2ovf
0xFFE4:FFE5
TPM2 Channel 1
Vtpm2ch1
0xFFE6:FFE7
TPM2 Channel 0
Vtpm2ch0
0xFFE8:FFE9
TPM1 Overflow
Vtpm1ovf
0xFFEA:FFEB
Unused
—
0xFFEC:FFED
Unused
—
0xFFEE:FFEF
TPM1 Channel 3
Vtpm1ch3
0xFFF0:FFF1
TPM1 Channel 2
Vtpm1ch2
0xFFF2:FFF3
TPM1 Channel 1
Vtpm1ch1
0xFFF4:FFF5
TPM1 Channel 0
Vtpm1ch0
0xFFF6:FFF7
ICG
Vicg
0xFFF8:FFF9
Low Voltage Detect
Vlvd
0xFFFA:FFFB
IRQ
Virq
0xFFFC:FFFD
SWI
Vswi
0xFFFE:FFFF
Reset
Vreset
TPM3 is not available on S9S08AWxxA
MC9S08AC16 Series Data Sheet, Rev. 0
42
PRELIMINARY
Freescale Semiconductor
Chapter 4 Memory
4.2
Register Addresses and Bit Assignments
The registers in the MC9S08AC16 Series are divided into these three groups:
• Direct-page registers are located in the first 112 locations in the memory map, so they are
accessible with efficient direct addressing mode instructions.
• High-page registers are used much less often, so they are located above 0x1800 in the memory
map. This leaves more room in the direct page for more frequently used registers and variables.
• The nonvolatile register area consists of a block of 16 locations in FLASH memory at
0xFFB0–0xFFBF.
Nonvolatile register locations include:
— Three values which are loaded into working registers at reset
— An 8-byte backdoor comparison key which optionally allows a user to gain controlled access
to secure memory
Because the nonvolatile register locations are FLASH memory, they must be erased and
programmed like other FLASH memory locations.
Direct-page registers can be accessed with efficient direct addressing mode instructions. Bit manipulation
instructions can be used to access any bit in any direct-page register. Table 4-2 is a summary of all
user-accessible direct-page registers and control bits.
The direct page registers in Table 4-2 can use the more efficient direct addressing mode which only
requires the lower byte of the address. Because of this, the lower byte of the address in column one is
shown in bold text. In Table 4-3 and Table 4-4 the whole address in column one is shown in bold. In
Table 4-2, Table 4-3, and Table 4-4, the register names in column two are shown in bold to set them apart
from the bit names to the right. Cells that are not associated with named bits are shaded. A shaded cell with
a 0 indicates this unused bit always reads as a 0. Shaded cells with dashes indicate unused or reserved bit
locations that could read as 1s or 0s.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
43
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 1 of 3)
Address
Register Name
0x0000
0x0001
0x0002
0x0003
0x0004
0x0005
0x0006
0x0007
0x0008
0x0009
0x000A
0x000B
PTAD
PTADD
PTBD
PTBDD
PTCD
PTCDD
PTDD
PTDDD
PTED
PTEDD
PTFD
PTFDD
0x000C
0x000D
0x000E–
0x000F
0x0010
0x0011
0x0012
0x0013
0x0014
0x0015
0x0016
0x0017
0x0018
0x0019
0x001A–
0x001B
0x001C
0x001D
0x001E
0x001F
0x0020
0x0021
0x0022
0x0023
0x0024
0x0025
0x0026
0x0027
PTGD
PTGDD
Reserved
ADC1SC1
ADC1SC2
ADC1RH
ADC1RL
ADC1CVH
ADC1CVL
ADC1CFG
APCTL1
APCTL2
APCTL3
Reserved
IRQSC
Reserved
KBISC
KBIPE
TPM1SC
TPM1CNTH
TPM1CNTL
TPM1MODH
TPM1MODL
TPM1C0SC
TPM1C0VH
TPM1C0VL
Bit 7
6
5
4
3
2
1
Bit 0
PTAD7
R
R
R
R
PTAD2
PTAD1
PTAD0
PTADD7
R
R
R
R
PTADD2
PTADD1
PTADD0
R
R
R
R
PTBD3
PTBD2
PTBD1
PTBD0
R
R
R
R
PTBDD3
PTBDD2
PTBDD1
PTBDD0
0
R
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0
R
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
R
R
R
R
PTDD3
PTDD2
PTDD1
PTDD0
R
R
R
R
PTDDD3
PTDDD2
PTDDD1
PTDDD0
PTED7
PTED6
PTED5
PTED4
PTED3
PTED2
PTED1
PTED0
PTEDD7
PTEDD6
PTEDD5
PTEDD4
PTEDD3
PTEDD2
PTEDD1
PTEDD0
R
PTFD6
PTFD5
PTFD4
R
R
PTFD1
PTFD0
R
PTFDD6
PTFDD5
PTFDD4
R
R
PTFDD1
PTFDD0
0
PTGD6
PTGD5
PTGD4
PTGD3
PTGD2
PTGD1
PTGD0
0
PTGDD6
PTGDD5
PTGDD4
PTGDD3
PTGDD2
PTGDD1
PTGDD0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
COCO
AIEN
ADCO
ADACT
ADTRG
ACFE
ACFGT
0
0
R
R
0
0
0
0
0
0
ADR9
ADR8
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
ADR0
0
0
0
0
0
0
ADCV9
ADCV8
ADCV7
ADCV6
ADCV5
ADCV4
ADCV3
ADCV2
ADCV1
ADCV0
ADLPC
ADIV
ADCH
ADLSMP
MODE
ADICLK
ADPC7
ADPC6
ADPC5
ADPC4
ADPC3
ADPC2
ADPC1
ADPC0
ADPC15
ADPC14
ADPC13
ADPC12
ADPC11
ADPC10
ADPC9
ADPC8
ADPC23
ADPC22
ADPC21
ADPC20
ADPC19
ADPC18
ADPC17
ADPC16
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0
IRQPDD
IRQEDG
IRQPE
IRQF
0
IRQIE
IRQMOD
—
—
—
—
—
—
—
—
KBEDG7
KBEDG6
KBEDG5
KBEDG4
KBF
KBACK
KBIE
KBIMOD
KBIPE7
KBIPE6
KBIPE5
KBIPE4
KBIPE3
KBIPE2
KBIPE1
KBIPE0
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
MC9S08AC16 Series Data Sheet, Rev. 0
44
PRELIMINARY
Freescale Semiconductor
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 2 of 3)
Address
Register Name
0x0028
0x0029
0x002A
0x002B
0x002C
0x002D
0x002E
0x002F
0x0030
0x0031–
0x0037
0x0038
TPM1C1SC
TPM1C1VH
TPM1C1VL
TPM1C2SC
TPM1C2VH
TPM1C2VL
TPM1C3SC
TPM1C3VH
TPM1C3VL
Reserved
0x0039
0x003A
0x003B
0x003C
0x003D
0x003E
0x003F
0x0040
0x0041
0x0042
0x0043
0x0044
0x0045
0x0046
0x0047
0x0048
0x0049
0x004A
0x004B
0x004C
0x004D
0x004E
0x004F
0x0050
0x0051
0x0052
0x0053
0x0054
Bit 7
6
5
4
3
2
1
Bit 0
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH2F
CH2IE
MS2B
MS2A
ELS2B
ELS2A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH3F
CH3IE
MS3B
MS3A
ELS3B
ELS3A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
—
SCI1BDH
LBKDIE
RXEDGIE
0
SBR12
SBR11
SBR10
SBR9
SBR8
SCI1BDL
SCI1C1
SCI1C2
SCI1S1
SCI1S2
SCI1C3
SCI1D
SCI2BDH
SCI2BDL
SCI2C1
SCI2C2
SCI2S1
SCI2S2
SCI2C3
SCI2D
ICGC1
ICGC2
ICGS1
ICGS2
ICGFLTU
ICGFLTL
ICGTRM
Reserved
SPI1C1
SPI1C2
SPI1BR
SPI1S
SPI1DH
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
LBKDIF
RXEDGIF
0
RXINV
RWUID
BRK13
LBKDE
RAF
R8
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
Bit 7
6
5
4
3
2
1
Bit 0
LBKDIE
RXEDGIE
0
SBR12
SBR11
SBR10
SBR9
SBR8
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
LBKDIF
RXEDGIF
0
RXINV
RWUID
BRK13
LBKDE
RAF
R8
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
Bit 7
6
5
4
3
2
1
Bit 0
HGO
RANGE
REFS
OSCSTEN
LOCD
0
LOLRE
CLKS
MFD
CLKST
LOCRE
RFD
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
0
0
0
DCOS
—
—
—
CPHA
SSOE
LSBFE
0
0
0
0
0
0
0
0
FLT
FLT
TRIM
—
—
—
—
—
SPIE
SPE
SPTIE
MSTR
CPOL
SPMIE
0
0
MODFEN
BIDIROE
0
SPPR2
SPPR1
SPPR0
0
SPR2
SPR1
SPR0
SPRF
SPIMF
SPTEF
MODF
0
0
0
0
Bit 15
14
13
12
11
10
8
Bit 8
SPIMODE SPISWAI
SPC0
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
45
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 3 of 3)
Address
0x0055
0x0056
0x0057
0x0058
0x0059
0x005A
0x005B
0x005C
0x005D
0x005E–
0x005F
0x0060
0x0061
0x0062
0x0063
0x0064
0x0065
0x0066
0x0067
0x0068
0x0069
0x006A
0x006B–
0x006F
Register Name
SPI1DL
SPI1MH
SPI1ML
IIC1A
IIC1F
IIC1C
IIC1S
IIC1D
IIC1C2
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
8
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
AD7
AD6
AD5
AD4
AD3
AD2
AD1
0
TXAK
RSTA
0
0
0
SRW
IICIF
RXAK
MULT
ICR
IICEN
IICIE
MST
TX
TCF
IAAS
BUSY
ARBL
DATA
GCAEN
ADEXT
0
0
0
AD10
AD9
AD8
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
TPM2SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
TPM2CNTH
TPM2CNTL
TPM2MODH
TPM2MODL
TPM2C0SC
TPM2C0VH
TPM2C0VL
TPM2C1SC
TPM2C1VH
TPM2C1VL
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Reserved
Reserved
Bit 7
6
5
4
3
2
1
Bit 0
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
High-page registers, shown in Table 4-3, are accessed much less often than other I/O and control registers
so they have been located outside the direct addressable memory space, starting at 0x1800.
Table 4-3. High-Page Register Summary (Sheet 1 of 3)
Address
0x1800
0x1801
0x1802
0x1803
0x1804 –
0x1805
0x1806
0x1807
0x1808
0x1809
0x180A
Register Name
SRS
SBDFR
SOPT
SMCLK
Reserved
SDIDH
SDIDL
SRTISC
SPMSC1
SPMSC2
Bit 7
6
5
4
3
2
1
Bit 0
POR
PIN
COP
ILOP
ILAD
ICG
LVD
0
0
0
0
0
0
0
0
BDFR
COPE
COPT
STOPE
—
0
0
—
—
0
0
0
MPE
0
—
—
—
—
—
—
—
—
—
—
—
—
MCSEL
—
—
—
—
REV3
REV2
REV1
REV0
ID11
ID10
ID9
ID8
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
RTIF
RTIACK
RTICLKS
RTIE
0
RTIS2
RTIS1
RTIS0
LVDF
LVDACK
LVDIE
LVDRE
LVDSE
LVDE
01
BGBE
LVWF
LVWACK
LVDV
LVWV
PPDF
PPDACK
—
PPDC
MC9S08AC16 Series Data Sheet, Rev. 0
46
PRELIMINARY
Freescale Semiconductor
Chapter 4 Memory
Table 4-3. High-Page Register Summary (Sheet 2 of 3)
Address
Register Name
0x180B
0x180C
0x180D–
0x180F
0x1810
0x1811
0x1812
0x1813
0x1814
0x1815
0x1816
0x1817
Reserved
SOPT2
0x1818
0x1819–
0x181F
0x1820
0x1821
0x1822
0x1823
0x1824
0x1825
0x1826
0x1827–
0x182F
0x1830
0x1831
0x1832
0x1833
0x1834
0x1835
0x1836
0x1837
0x1838
0x1839
0x183A
0x183B
0x183F
0x1840
0x1841
0x1842
DBGS
Reserved
Reserved
DBGCAH
DBGCAL
DBGCBH
DBGCBL
DBGFH
DBGFL
DBGC
DBGT
FCDIV
FOPT
Reserved
FCNFG
FPROT
FSTAT
FCMD
Reserved
TPM3SC2
TPM3CNTH2
TPM3CNTL2
TPM3MODH2
TPM3MODL2
TPM3C0SC2
TPM3C0VH2
TPM3C0VL2
TPM3C1SC2
TPM3C1VH2
TPM3C1VL2
Reserved
PTAPE
PTASE
PTADS
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
—
COPCLKS
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
DBGEN
ARM
TAG
BRKEN
RWA
RWAEN
RWB
RWBEN
TRGSEL
BEGIN
0
0
TRG3
TRG2
TRG1
TRG0
AF
BF
ARMF
0
CNT3
CNT2
CNT1
CNT0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
DIVLD
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
—
—
—
—
—
—
—
—
0
0
KEYACC
0
0
0
0
0
FPS7
FPS6
FPS5
FPS4
FPS3
FPS2
FPS1
FPDIS
FCBEF
FCCF
FPVIOL
FACCERR
0
FBLANK
0
0
FCMD7
FCMD6
FCMD5
FCMD4
FCMD3
FCMD2
FCMD1
FCMD0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
Bit 15
14
13
12
11
10
9
Bit 8
Bit 7
6
5
4
3
2
1
Bit 0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
PTAPE7
R
R
R
R
PTAPE2
PTAPE1
PTAPE0
PTASE7
R
R
R
R
PTASE2
PTASE1
PTASE0
PTADS7
R
R
R
R
PTADS2
PTADS1
PTADS0
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
47
Chapter 4 Memory
Table 4-3. High-Page Register Summary (Sheet 3 of 3)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0x1843
0x1844
0x1845
0x1846
0x1847
0x1848
0x1849
0x184A
0x184B
0x184C
0x184D
0x184E
Reserved
PTBPE
PTBSE
PTBDS
Reserved
PTCPE
PTCSE
PTCDS
Reserved
PTDPE
PTDSE
PTDDS
—
—
—
—
—
—
—
—
R
R
R
R
PTBPE3
PTBPE2
PTBPE1
PTBPE0
R
R
R
R
PTBSE3
PTBSE2
PTBSE1
PTBSE0
R
R
R
R
PTBDS3
PTBDS2
PTBDS1
PTBDS0
—
—
—
—
—
—
—
—
0
R
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0
R
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
0
R
PTCDS5
PTCDS4
PTCDS3
PTCDS2
PTCDS1
PTCDS0
—
—
—
—
—
—
—
—
R
R
R
R
PTDPE3
PTDPE2
PTDPE1
PTDPE0
R
R
R
R
PTDSE3
PTDSE2
PTDSE1
PTDSE0
R
R
R
R
PTDDS3
PTDDS2
PTDDS1
PTDDS0
0x184F
0x1850
0x1851
0x1852
0x1853
0x1854
0x1855
0x1856
0x1857
0x1858
0x1859
0x185A
0x185B–
0x185F
Reserved
PTEPE
PTESE
PTEDS
Reserved
PTFPE
PTFSE
PTFDS
Reserved
PTGPE
PTGSE
PTGDS
—
—
—
—
—
—
—
—
PTEPE7
PTEPE6
PTEPE5
PTEPE4
PTEPE3
PTEPE2
PTEPE1
PTEPE0
1
2
Reserved
PTESE7
PTESE6
PTESE5
PTESE4
PTESE3
PTESE2
PTESE1
PTESE0
PTEDS7
PTEDS6
PTEDS5
PTEDS4
PTEDS3
PTEDS2
PTEDS1
PTEDS0
—
—
—
—
—
—
—
—
R
PTFPE6
PTFPE5
PTFPE4
R
R
PTFPE1
PTFPE0
R
PTFSE6
PTFSE5
PTFSE4
R
R
PTFSE1
PTFSE0
R
PTFDS6
PTFDS5
PTFDS4
R
R
PTFDS1
PTFDS0
—
—
—
—
—
—
—
—
0
PTGPE6
PTGPE5
PTGPE4
PTGPE3
PTGPE2
PTGPE1
PTGPE0
0
PTGSE6
PTGSE5
PTGSE4
PTGSE3
PTGSE2
PTGSE1
PTGSE0
0
PTGDS6
PTGDS5
PTGDS4
PTGDS3
PTGDS2
PTGDS1
PTGDS0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
This reserved bit must always be written to 0.
MC9S08AC16 and MC9S08AC8 devices only.
Nonvolatile FLASH registers, shown in Table 4-4, are located in the FLASH memory. These registers
include an 8-byte backdoor key which optionally can be used to gain access to secure memory resources.
During reset events, the contents of NVPROT and NVOPT in the nonvolatile register area of the FLASH
memory are transferred into corresponding FPROT and FOPT working registers in the high-page registers
to control security and block protection options.
MC9S08AC16 Series Data Sheet, Rev. 0
48
PRELIMINARY
Freescale Semiconductor
Chapter 4 Memory
Table 4-4. Nonvolatile Register Summary
Address
0xFFB0 –
0xFFB7
0xFFB8 –
0xFFBC
0xFFBD
0xFFBE
0xFFBF
1
Register Name
Bit 7
6
5
NVBACKKEY
4
3
2
1
Bit 0
8-Byte Comparison Key
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
NVPROT
Reserved1
NVOPT
FPS7
FPS6
FPS5
FPS4
FPS3
FPS2
FPS1
FPDIS
—
—
—
—
—
—
—
—
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
This location can be used to store the factory trim value for the ICG.
Provided the key enable (KEYEN) bit is 1, the 8-byte comparison key can be used to temporarily
disengage memory security. This key mechanism can be accessed only through user code running in secure
memory. (A security key cannot be entered directly through background debug commands.) This security
key can be disabled completely by programming the KEYEN bit to 0. If the security key is disabled, the
only way to disengage security is by mass erasing the FLASH if needed (normally through the background
debug interface) and verifying that FLASH is blank. To avoid returning to secure mode after the next reset,
program the security bits (SEC01:SEC00) to the unsecured state (1:0).
4.3
RAM
The MC9S08AC16 Series includes static RAM. The locations in RAM below 0x0100 can be accessed
using the more efficient direct addressing mode, and any single bit in this area can be accessed with the bit
manipulation instructions (BCLR, BSET, BRCLR, and BRSET). Locating the most frequently accessed
program variables in this area of RAM is preferred.
The RAM retains data when the MCU is in low-power wait, stop2, or stop3 mode. At power-on, the
contents of RAM are uninitialized. RAM data is unaffected by any reset provided that the supply voltage
does not drop below the minimum value for RAM retention.
For compatibility with older M68HC05 MCUs, the HCS08 resets the stack pointer to 0x00FF. In the
MC9S08AC16 Series, it is usually best to re-initialize the stack pointer to the top of the RAM so the direct
page RAM can be used for frequently accessed RAM variables and bit-addressable program variables.
Include the following 2-instruction sequence in your reset initialization routine (where RamLast is equated
to the highest address of the RAM in the Freescale-provided equate file).
LDHX
TXS
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
When security is enabled, the RAM is considered a secure memory resource and is not accessible through
BDM or through code executing from non-secure memory. See Section 4.5, “Security” for a detailed
description of the security feature.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
49
Chapter 4 Memory
4.4
FLASH
The FLASH memory is intended primarily for program storage. In-circuit programming allows the
operating program to be loaded into the FLASH memory after final assembly of the application product.
It is possible to program the entire array through the single-wire background debug interface. Because no
special voltages are needed for FLASH erase and programming operations, in-application programming
is also possible through other software-controlled communication paths. For a more detailed discussion of
in-circuit and in-application programming, refer to the HCS08 Family Reference Manual, Volume I,
Freescale Semiconductor document order number HCS08RMv1/D.
4.4.1
Features
Features of the FLASH memory include:
• FLASH Size
— MC9S08AC16 and S9S08AW16A— 16,384 bytes (32 pages of 512 bytes each)
— MC9S08AC8 and S9S08AW8A— 8192 bytes (16 pages of 512 bytes each)
• Single power supply program and erase
• Command interface for fast program and erase operation
• Up to 100,000 program/erase cycles at typical voltage and temperature
• Flexible block protection
• Security feature for FLASH and RAM
• Auto power-down for low-frequency read accesses
4.4.2
Program and Erase Times
Before any program or erase command can be accepted, the FLASH clock divider register (FCDIV) must
be written to set the internal clock for the FLASH module to a frequency (fFCLK) between 150 kHz and
200 kHz (see Section 4.6.1, “FLASH Clock Divider Register (FCDIV)”). This register can be written only
once, so normally this write is done during reset initialization. FCDIV cannot be written if the access error
flag, FACCERR in FSTAT, is set. The user must ensure that FACCERR is not set before writing to the
FCDIV register. One period of the resulting clock (1/fFCLK) is used by the command processor to time
program and erase pulses. An integer number of these timing pulses are used by the command processor
to complete a program or erase command.
Table 4-5 shows program and erase times. The bus clock frequency and FCDIV determine the frequency
of FCLK (fFCLK). The time for one cycle of FCLK is tFCLK = 1/fFCLK. The times are shown as a number
of cycles of FCLK and as an absolute time for the case where tFCLK = 5 μs. Program and erase times
shown include overhead for the command state machine and enabling and disabling of program and erase
voltages.
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Table 4-5. Program and Erase Times
Parameter
Cycles of FCLK
Time if FCLK = 200 kHz
Byte program
9
45 μs
Byte program (burst)
4
20 μs1
Page erase
4000
20 ms
Mass erase
20,000
100 ms
1
4.4.3
Excluding start/end overhead
Program and Erase Command Execution
The steps for executing any of the commands are listed below. The FCDIV register must be initialized and
any error flags cleared before beginning command execution. The command execution steps are:
1. Write a data value to an address in the FLASH array. The address and data information from this
write is latched into the FLASH interface. This write is a required first step in any command
sequence. For erase and blank check commands, the value of the data is not important. For page
erase commands, the address may be any address in the 512-byte page of FLASH to be erased. For
mass erase and blank check commands, the address can be any address in the FLASH memory.
Whole pages of 512 bytes are the smallest block of FLASH that may be erased. In the 60K version,
there are two instances where the size of a block that is accessible to the user is less than 512 bytes:
the first page following RAM, and the first page following the high page registers. These pages are
overlapped by the RAM and high page registers respectively.
NOTE
Do not program any byte in the FLASH more than once after a successful
erase operation. Reprogramming bits to a byte which is already
programmed is not allowed without first erasing the page in which the byte
resides or mass erasing the entire FLASH memory. Programming without
first erasing may disturb data stored in the FLASH.
2. Write the command code for the desired command to FCMD. The five valid commands are blank
check (0x05), byte program (0x20), burst program (0x25), page erase (0x40), and mass erase
(0x41). The command code is latched into the command buffer.
3. Write a 1 to the FCBEF bit in FSTAT to clear FCBEF and launch the command (including its
address and data information).
A partial command sequence can be aborted manually by writing a 0 to FCBEF any time after the write to
the memory array and before writing the 1 that clears FCBEF and launches the complete command.
Aborting a command in this way sets the FACCERR access error flag which must be cleared before
starting a new command.
A strictly monitored procedure must be obeyed or the command will not be accepted. This minimizes the
possibility of any unintended changes to the FLASH memory contents. The command complete flag
(FCCF) indicates when a command is complete. The command sequence must be completed by clearing
FCBEF to launch the command. Figure 4-2 is a flowchart for executing all of the commands except for
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burst programming. The FCDIV register must be initialized before using any FLASH commands. This
only must be done once following a reset.
WRITE TO FCDIV (Note 1)
FLASH PROGRAM AND
ERASE FLOW
Note 1: Required only once after reset.
START
FACCERR ?
0
1
CLEAR ERROR
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND TO FCMD
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (Note 2)
FPVIOL OR
FACCERR ?
Note 2: Wait at least four bus cycles
before checking FCBEF or FCCF.
YES
ERROR EXIT
NO
0
FCCF ?
1
DONE
Figure 4-2. FLASH Program and Erase Flowchart
4.4.4
Burst Program Execution
The burst program command is used to program sequential bytes of data in less time than would be
required using the standard program command. This is possible because the high voltage to the FLASH
array does not need to be disabled between program operations. Ordinarily, when a program or erase
command is issued, an internal charge pump associated with the FLASH memory must be enabled to
supply high voltage to the array. Upon completion of the command, the charge pump is turned off. When
a burst program command is issued, the charge pump is enabled and then remains enabled after completion
of the burst program operation if these two conditions are met:
• The next burst program command has been queued before the current program operation has
completed.
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•
The next sequential address selects a byte on the same physical row as the current byte being
programmed. A row of FLASH memory consists of 64 bytes. A byte within a row is selected by
addresses A5 through A0. A new row begins when addresses A5 through A0 are all zero.
The first byte of a series of sequential bytes being programmed in burst mode will take the same amount
of time to program as a byte programmed in standard mode. Subsequent bytes will program in the burst
program time provided that the conditions above are met. In the case the next sequential address is the
beginning of a new row, the program time for that byte will be the standard time instead of the burst time.
This is because the high voltage to the array must be disabled and then enabled again. If a new burst
command has not been queued before the current command completes, then the charge pump will be
disabled and high voltage removed from the array.
Note 1: Required only once after reset.
WRITE TO FCDIV (Note 1)
FLASH BURST
PROGRAM FLOW
START
FACCERR ?
1
0
CLEAR ERROR
FCBEF ?
1
0
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND (0x25) TO FCMD
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (Note 2)
FPVIO OR
FACCERR ?
NO
YES
Note 2: Wait at least four bus cycles before
checking FCBEF or FCCF.
YES
ERROR EXIT
NEW BURST COMMAND ?
NO
0
FCCF ?
1
DONE
Figure 4-3. FLASH Burst Program Flowchart
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4.4.5
Access Errors
An access error occurs whenever the command execution protocol is violated.
Any of the following specific actions will cause the access error flag (FACCERR) in FSTAT to be set.
FACCERR must be cleared by writing a 1 to FACCERR in FSTAT before any command can be processed.
• Writing to a FLASH address before the internal FLASH clock frequency has been set by writing
to the FCDIV register
• Writing to a FLASH address while FCBEF is not set (A new command cannot be started until the
command buffer is empty.)
• Writing a second time to a FLASH address before launching the previous command (There is only
one write to FLASH for every command.)
• Writing a second time to FCMD before launching the previous command (There is only one write
to FCMD for every command.)
• Writing to any FLASH control register other than FCMD after writing to a FLASH address
• Writing any command code other than the five allowed codes (0x05, 0x20, 0x25, 0x40, or 0x41)
to FCMD
• Writing any FLASH control register other than the write to FSTAT (to clear FCBEF and launch the
command) after writing the command to FCMD.
• The MCU enters stop mode while a program or erase command is in progress (The command is
aborted.)
• Writing the byte program, burst program, or page erase command code (0x20, 0x25, or 0x40) with
a background debug command while the MCU is secured (The background debug controller can
only do blank check and mass erase commands when the MCU is secure.)
• Writing 0 to FCBEF to cancel a partial command
4.4.6
FLASH Block Protection
The block protection feature prevents the protected region of FLASH from program or erase changes.
Block protection is controlled through the FLASH protection register (FPROT). When enabled, block
protection begins at any 512 byte boundary below the last address of FLASH, 0xFFFF. (See Section 4.6.4,
“FLASH Protection Register (FPROT and NVPROT)”).
After exit from reset, FPROT is loaded with the contents of the NVPROT location, which is in the
nonvolatile register block of the FLASH memory. FPROT cannot be changed directly from application
software so a runaway program cannot alter the block protection settings. Because NVPROT is within the
last 512 bytes of FLASH, if any amount of memory is protected, NVPROT is itself protected and cannot
be altered (intentionally or unintentionally) by the application software. FPROT can be written through
background debug commands, which allows a way to erase and reprogram a protected FLASH memory.
The block protection mechanism is illustrated in Figure 4-4. The FPS bits are used as the upper bits of the
last address of unprotected memory. This address is formed by concatenating FPS7:FPS1 with logic 1 bits
as shown. For example, to protect the last 1536 bytes of memory (addresses 0xFA00 through 0xFFFF), the
FPS bits must be set to 1111 100, which results in the value 0xF9FF as the last address of unprotected
memory. In addition to programming the FPS bits to the appropriate value, FPDIS (bit 0 of NVPROT) must
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be programmed to logic 0 to enable block protection. Therefore the value 0xF8 must be programmed into
NVPROT to protect addresses 0xFA00 through 0xFFFF.
FPS7 FPS6 FPS5 FPS4 FPS3 FPS2 FPS1
A15
A14
A13
A12
A11
A10
A9
1
1
1
1
1
1
1
1
1
A8 A7 A6 A5 A4 A3 A2 A1 A0
Figure 4-4. Block Protection Mechanism
One use for block protection is to block protect an area of FLASH memory for a bootloader program. This
bootloader program then can be used to erase the rest of the FLASH memory and reprogram it. Because
the bootloader is protected, it remains intact even if MCU power is lost in the middle of an erase and
reprogram operation.
4.4.7
Vector Redirection
Whenever any block protection is enabled, the reset and interrupt vectors will be protected. Vector
redirection allows users to modify interrupt vector information without unprotecting bootloader and reset
vector space. Vector redirection is enabled by programming the FNORED bit in the NVOPT register
located at address 0xFFBF to zero. For redirection to occur, at least some portion but not all of the FLASH
memory must be block protected by programming the NVPROT register located at address 0xFFBD. All
of the interrupt vectors (memory locations 0xFFC0–0xFFFD) are redirected, though the reset vector
(0xFFFE:FFFF) is not.
For example, if 512 bytes of FLASH are protected, the protected address region is from 0xFE00 through
0xFFFF. The interrupt vectors (0xFFC0–0xFFFD) are redirected to the locations 0xFDC0–0xFDFD. Now,
if an SPI interrupt is taken for instance, the values in the locations 0xFDE0:FDE1 are used for the vector
instead of the values in the locations 0xFFE0:FFE1. This allows the user to reprogram the unprotected
portion of the FLASH with new program code including new interrupt vector values while leaving the
protected area, which includes the default vector locations, unchanged.
4.5
Security
The MC9S08AC16 Series includes circuitry to prevent unauthorized access to the contents of FLASH and
RAM memory. When security is engaged, FLASH and RAM are considered secure resources. Direct-page
registers, high-page registers, and the background debug controller are considered unsecured resources.
Programs executing within secure memory have normal access to any MCU memory locations and
resources. Attempts to access a secure memory location with a program executing from an unsecured
memory space or through the background debug interface are blocked (writes are ignored and reads return
all 0s).
Security is engaged or disengaged based on the state of two nonvolatile register bits (SEC01:SEC00) in
the FOPT register. During reset, the contents of the nonvolatile location NVOPT are copied from FLASH
into the working FOPT register in high-page register space. A user engages security by programming the
NVOPT location which can be done at the same time the FLASH memory is programmed. The 1:0 state
disengages security and the other three combinations engage security. Notice the erased state (1:1) makes
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the MCU secure. During development, whenever the FLASH is erased, it is good practice to immediately
program the SEC00 bit to 0 in NVOPT so SEC01:SEC00 = 1:0. This would allow the MCU to remain
unsecured after a subsequent reset.
The on-chip debug module cannot be enabled while the MCU is secure. The separate background debug
controller can still be used for background memory access commands, but the MCU cannot enter active
background mode except by holding BKGD/MS low at the rising edge of reset.
A user can choose to allow or disallow a security unlocking mechanism through an 8-byte backdoor
security key. If the nonvolatile KEYEN bit in NVOPT/FOPT is 0, the backdoor key is disabled and there
is no way to disengage security without completely erasing all FLASH locations. If KEYEN is 1, a secure
user program can temporarily disengage security by:
1. Writing 1 to KEYACC in the FCNFG register. This makes the FLASH module interpret writes to
the backdoor comparison key locations (NVBACKKEY through NVBACKKEY+7) as values to
be compared against the key rather than as the first step in a FLASH program or erase command.
2. Writing the user-entered key values to the NVBACKKEY through NVBACKKEY+7 locations.
These writes must be done in order starting with the value for NVBACKKEY and ending with
NVBACKKEY+7. STHX should not be used for these writes because these writes cannot be done
on adjacent bus cycles. User software normally would get the key codes from outside the MCU
system through a communication interface such as a serial I/O.
3. Writing 0 to KEYACC in the FCNFG register. If the 8-byte key that was just written matches the
key stored in the FLASH locations, SEC01:SEC00 are automatically changed to 1:0 and security
will be disengaged until the next reset.
The security key can be written only from secure memory (either RAM or FLASH), so it cannot be entered
through background commands without the cooperation of a secure user program.
The backdoor comparison key (NVBACKKEY through NVBACKKEY+7) is located in FLASH memory
locations in the nonvolatile register space so users can program these locations exactly as they would
program any other FLASH memory location. The nonvolatile registers are in the same 512-byte block of
FLASH as the reset and interrupt vectors, so block protecting that space also block protects the backdoor
comparison key. Block protects cannot be changed from user application programs, so if the vector space
is block protected, the backdoor security key mechanism cannot permanently change the block protect,
security settings, or the backdoor key.
Security can always be disengaged through the background debug interface by taking these steps:
1. Disable any block protections by writing FPROT. FPROT can be written only with background
debug commands, not from application software.
2. Mass erase FLASH if necessary.
3. Blank check FLASH. Provided FLASH is completely erased, security is disengaged until the next
reset.
To avoid returning to secure mode after the next reset, program NVOPT so SEC01:SEC00 = 1:0.
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4.6
FLASH Registers and Control Bits
The FLASH module has nine 8-bit registers in the high-page register space, three locations in the
nonvolatile register space in FLASH memory which are copied into three corresponding high-page control
registers at reset. There is also an 8-byte comparison key in FLASH memory. Refer to Table 4-3 and
Table 4-4 for the absolute address assignments for all FLASH registers. This section refers to registers and
control bits only by their names. A Freescale-provided equate or header file normally is used to translate
these names into the appropriate absolute addresses.
4.6.1
FLASH Clock Divider Register (FCDIV)
Bit 7 of this register is a read-only status flag. Bits 6 through 0 may be read at any time but can be written
only one time. Before any erase or programming operations are possible, write to this register to set the
frequency of the clock for the nonvolatile memory system within acceptable limits.
7
R
6
5
4
3
2
1
0
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
0
0
0
0
0
0
0
DIVLD
W
Reset
0
= Unimplemented or Reserved
Figure 4-5. FLASH Clock Divider Register (FCDIV)
Table 4-6. FCDIV Register Field Descriptions
Field
Description
7
DIVLD
Divisor Loaded Status Flag — When set, this read-only status flag indicates that the FCDIV register has been
written since reset. Reset clears this bit and the first write to this register causes this bit to become set regardless
of the data written.
0 FCDIV has not been written since reset; erase and program operations disabled for FLASH.
1 FCDIV has been written since reset; erase and program operations enabled for FLASH.
6
PRDIV8
Prescale (Divide) FLASH Clock by 8
0 Clock input to the FLASH clock divider is the bus rate clock.
1 Clock input to the FLASH clock divider is the bus rate clock divided by 8.
5:0
DIV[5:0]
Divisor for FLASH Clock Divider — The FLASH clock divider divides the bus rate clock (or the bus rate clock
divided by 8 if PRDIV8 = 1) by the value in the 6-bit DIV5:DIV0 field plus one. The resulting frequency of the
internal FLASH clock must fall within the range of 200 kHz to 150 kHz for proper FLASH operations.
Program/Erase timing pulses are one cycle of this internal FLASH clock which corresponds to a range of 5 μs to
6.7 μs. The automated programming logic uses an integer number of these pulses to complete an erase or
program operation. See Equation 4-1, Equation 4-2, and Table 4-6.
if PRDIV8 = 0 — fFCLK = fBus ÷ ([DIV5:DIV0] + 1)
Eqn. 4-1
if PRDIV8 = 1 — fFCLK = fBus ÷ (8 × ([DIV5:DIV0] + 1))
Eqn. 4-2
Table 4-7 shows the appropriate values for PRDIV8 and DIV5:DIV0 for selected bus frequencies.
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Table 4-7. FLASH Clock Divider Settings
fBus
PRDIV8
(Binary)
DIV5:DIV0
(Decimal)
fFCLK
Program/Erase Timing Pulse
(5 μs Min, 6.7 μs Max)
20 MHz
1
12
192.3 kHz
5.2 μs
10 MHz
0
49
200 kHz
5 μs
8 MHz
0
39
200 kHz
5 μs
4 MHz
0
19
200 kHz
5 μs
2 MHz
0
9
200 kHz
5 μs
1 MHz
0
4
200 kHz
5 μs
200 kHz
0
0
200 kHz
5 μs
150 kHz
0
0
150 kHz
6.7 μs
4.6.2
FLASH Options Register (FOPT and NVOPT)
During reset, the contents of the nonvolatile location NVOPT are copied from FLASH into FOPT. Bits 5
through 2 are not used and always read 0. This register may be read at any time, but writes have no meaning
or effect. To change the value in this register, erase and reprogram the NVOPT location in FLASH memory
as usual and then issue a new MCU reset.
R
7
6
5
4
3
2
1
0
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
W
Reset
This register is loaded from nonvolatile location NVOPT during reset.
= Unimplemented or Reserved
Figure 4-6. FLASH Options Register (FOPT)
Table 4-8. FOPT Register Field Descriptions
Field
Description
7
KEYEN
Backdoor Key Mechanism Enable — When this bit is 0, the backdoor key mechanism cannot be used to
disengage security. The backdoor key mechanism is accessible only from user (secured) firmware. BDM
commands cannot be used to write key comparison values that would unlock the backdoor key. For more detailed
information about the backdoor key mechanism, refer to Section 4.5, “Security.”
0 No backdoor key access allowed.
1 If user firmware writes an 8-byte value that matches the nonvolatile backdoor key (NVBACKKEY through
NVBACKKEY+7 in that order), security is temporarily disengaged until the next MCU reset.
6
FNORED
Vector Redirection Disable — When this bit is 1, then vector redirection is disabled.
0 Vector redirection enabled.
1 Vector redirection disabled.
1:0
SEC0[1:0]
Security State Code — This 2-bit field determines the security state of the MCU as shown in Table 4-9. When
the MCU is secure, the contents of RAM and FLASH memory cannot be accessed by instructions from any
unsecured source including the background debug interface. For more detailed information about security, refer
to Section 4.5, “Security.”
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Table 4-9. Security States
SEC01:SEC00
Description
0:0
secure
0:1
secure
1:0
unsecured
1:1
secure
SEC01:SEC00 changes to 1:0 after successful backdoor key entry or a successful blank check of FLASH.
4.6.3
FLASH Configuration Register (FCNFG)
Bits 7 through 5 may be read or written at any time. Bits 4 through 0 always read 0 and cannot be written.
R
7
6
0
0
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
KEYACC
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 4-7. FLASH Configuration Register (FCNFG)
Table 4-10. FCNFG Register Field Descriptions
Field
Description
5
KEYACC
Enable Writing of Access Key — This bit enables writing of the backdoor comparison key. For more detailed
information about the backdoor key mechanism, refer to Section 4.5, “Security.”
0 Writes to 0xFFB0–0xFFB7 are interpreted as the start of a FLASH programming or erase command.
1 Writes to NVBACKKEY (0xFFB0–0xFFB7) are interpreted as comparison key writes.
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4.6.4
FLASH Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT are copied from FLASH into FPROT. This
register can be read at any time. If FPDIS = 0, protection can be increased, i.e., a smaller value of FPS can
be written. If FPDIS = 1, writes do not change protection.
7
6
5
R
4
3
2
1
FPS(1)
0
FPDIS(1)
W
Reset
1
This register is loaded from nonvolatile location NVPROT during reset.
Background commands can be used to change the contents of these bits in FPROT.
Figure 4-8. FLASH Protection Register (FPROT)
Table 4-11. FPROT Register Field Descriptions
Field
Description
7:1
FPS[7:1]
FLASH Protect Select Bits — When FPDIS = 0, this 7-bit field determines the ending address of unprotected
FLASH locations at the high address end of the FLASH. Protected FLASH locations cannot be erased or
programmed.
0
FPDIS
4.6.5
FLASH Protection Disable
0 FLASH block specified by FPS[7:1] is block protected (program and erase not allowed).
1 No FLASH block is protected.
FLASH Status Register (FSTAT)
Bits 3, 1, and 0 always read 0 and writes have no meaning or effect. The remaining five bits are status bits
that can be read at any time. Writes to these bits have special meanings that are discussed in the bit
descriptions.
7
R
6
5
4
FPVIOL
FACCERR
0
0
FCCF
FCBEF
3
2
1
0
0
FBLANK
0
0
0
0
0
0
W
Reset
1
1
= Unimplemented or Reserved
Figure 4-9. FLASH Status Register (FSTAT)
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Table 4-12. FSTAT Register Field Descriptions
Field
Description
7
FCBEF
FLASH Command Buffer Empty Flag — The FCBEF bit is used to launch commands. It also indicates that the
command buffer is empty so that a new command sequence can be executed when performing burst
programming. The FCBEF bit is cleared by writing a one to it or when a burst program command is transferred
to the array for programming. Only burst program commands can be buffered.
0 Command buffer is full (not ready for additional commands).
1 A new burst program command may be written to the command buffer.
6
FCCF
FLASH Command Complete Flag — FCCF is set automatically when the command buffer is empty and no
command is being processed. FCCF is cleared automatically when a new command is started (by writing 1 to
FCBEF to register a command). Writing to FCCF has no meaning or effect.
0 Command in progress
1 All commands complete
5
FPVIOL
Protection Violation Flag — FPVIOL is set automatically when FCBEF is cleared to register a command that
attempts to erase or program a location in a protected block (the erroneous command is ignored). FPVIOL is
cleared by writing a 1 to FPVIOL.
0 No protection violation.
1 An attempt was made to erase or program a protected location.
4
FACCERR
Access Error Flag — FACCERR is set automatically when the proper command sequence is not obeyed exactly
(the erroneous command is ignored), if a program or erase operation is attempted before the FCDIV register has
been initialized, or if the MCU enters stop while a command was in progress. For a more detailed discussion of
the exact actions that are considered access errors, see Section 4.4.5, “Access Errors.” FACCERR is cleared by
writing a 1 to FACCERR. Writing a 0 to FACCERR has no meaning or effect.
0 No access error.
1 An access error has occurred.
2
FBLANK
FLASH Verified as All Blank (erased) Flag — FBLANK is set automatically at the conclusion of a blank check
command if the entire FLASH array was verified to be erased. FBLANK is cleared by clearing FCBEF to write a
new valid command. Writing to FBLANK has no meaning or effect.
0 After a blank check command is completed and FCCF = 1, FBLANK = 0 indicates the FLASH array is not
completely erased.
1 After a blank check command is completed and FCCF = 1, FBLANK = 1 indicates the FLASH array is
completely erased (all 0xFF).
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4.6.6
FLASH Command Register (FCMD)
Only five command codes are recognized in normal user modes as shown in Table 4-14. Refer to
Section 4.4.3, “Program and Erase Command Execution” for a detailed discussion of FLASH
programming and erase operations.
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
0
W
FCMD7
FCMD6
FCMD5
FCMD4
FCMD3
FCMD2
FCMD1
FCMD0
0
0
0
0
0
0
0
0
Reset
Figure 4-10. FLASH Command Register (FCMD)
Table 4-13. FCMD Register Field Descriptions
Field
7:0
FCMD[7:0]
Description
FLASH Command Bits — See Table 4-14
Table 4-14. FLASH Commands
Command
FCMD
Equate File Label
Blank check
0x05
mBlank
Byte program
0x20
mByteProg
Byte program — burst mode
0x25
mBurstProg
Page erase (512 bytes/page)
0x40
mPageErase
Mass erase (all FLASH)
0x41
mMassErase
All other command codes are illegal and generate an access error.
It is not necessary to perform a blank check command after a mass erase operation. Only blank check is
required as part of the security unlocking mechanism.
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Chapter 5
Resets, Interrupts, and System Configuration
5.1
Introduction
This chapter discusses basic reset and interrupt mechanisms and the various sources of reset and interrupts
in the MC9S08AC16 Series. Some interrupt sources from peripheral modules are discussed in greater
detail within other chapters of this data manual. This chapter gathers basic information about all reset and
interrupt sources in one place for easy reference. A few reset and interrupt sources, including the computer
operating properly (COP) watchdog and real-time interrupt (RTI), are not part of on-chip peripheral
systems with their own sections but are part of the system control logic.
5.2
Features
Reset and interrupt features include:
• Multiple sources of reset for flexible system configuration and reliable operation:
— Power-on detection (POR)
— Low voltage detection (LVD) with enable
— External RESET pin
— COP watchdog with enable and two timeout choices
— Illegal opcode
— Illegal address
— Serial command from a background debug host
• Reset status register (SRS) to indicate source of most recent reset
• Separate interrupt vectors for each module (reduces polling overhead) (see Table 5-11)
5.3
MCU Reset
Resetting the MCU provides a way to start processing from a known set of initial conditions. During reset,
most control and status registers are forced to initial values and the program counter is loaded from the
reset vector (0xFFFE:0xFFFF). On-chip peripheral modules are disabled and I/O pins are initially
configured as general-purpose high-impedance inputs with pullup devices disabled. The I bit in the
condition code register (CCR) is set to block maskable interrupts so the user program has a chance to
initialize the stack pointer (SP) and system control settings. SP is forced to 0x00FF at reset.
The following sources of reset are available on the MC9S08AC16 Series:
• Power-on reset (POR)
• Low-voltage detect (LVD)
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•
•
•
•
•
•
Computer operating properly (COP) timer
Illegal opcode detect
Illegal address detect
Background debug forced reset
The reset pin (RESET)
Clock generator loss of lock and loss of clock reset
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status register.
5.4
Computer Operating Properly (COP) Watchdog
The COP watchdog is intended to force a system reset when the application software fails to execute as
expected. To prevent a system reset from the COP timer (when it is enabled), application software must
reset the COP counter periodically. If the application program gets lost and fails to reset the COP counter
before it times out, a system reset is generated to force the system back to a known starting point.
After any reset, the COPE becomes set in SOPT enabling the COP watchdog (see Section 5.9.4, “System
Options Register (SOPT),” for additional information). If the COP watchdog is not used in an application,
it can be disabled by clearing COPE. The COP counter is reset by writing any value to the address of SRS.
This write does not affect the data in the read-only SRS. Instead, the act of writing to this address is
decoded and sends a reset signal to the COP counter.
The COPCLKS bit in SOPT2 (see Section 5.9.10, “System Options Register 2 (SOPT2),” for additional
information) selects the clock source used for the COP timer. The clock source options are either the bus
clock or an internal 1-kHz clock source. With each clock source, there is an associated short and long
time-out controlled by COPT in SOPT. Table 5-1 summaries the control functions of the COPCLKS and
COPT bits. The COP watchdog defaults to operation from the bus clock source and the associated long
time-out (218 cycles).
Table 5-1. COP Configuration Options
Control Bits
1
Clock Source
COP Overflow Count
0
~1 kHz
25 cycles (32 ms)1
0
1
~1 kHz
28 cycles (256 ms)1
1
0
Bus
213 cycles
1
1
Bus
218 cycles
COPCLKS
COPT
0
Values are shown in this column based on tRTI = 1 ms. See tRTI in the appendix
Section A.10.1, “Control Timing,” for the tolerance of this value.
Even if the application will use the reset default settings of COPE, COPCLKS, and COPT, the user must
write to the write-once SOPT and SOPT2 registers during reset initialization to lock in the settings. That
way, they cannot be changed accidentally if the application program gets lost. The initial writes to SOPT
and SOPT2 will reset the COP counter.
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The write to SRS that services (clears) the COP counter must not be placed in an interrupt service routine
(ISR) because the ISR could continue to be executed periodically even if the main application program
fails.
In background debug mode, the COP counter will not increment.
When the bus clock source is selected, the COP counter does not increment while the system is in stop
mode. The COP counter resumes as soon as the MCU exits stop mode.
When the 1-kHz clock source is selected, the COP counter is re-initialized to zero upon entry to stop mode.
The COP counter begins from zero after the MCU exits stop mode.
5.5
Interrupts
Interrupts provide a way to save the current CPU status and registers, execute an interrupt service routine
(ISR), and then restore the CPU status so processing resumes where it left off before the interrupt. Other
than the software interrupt (SWI), which is a program instruction, interrupts are caused by hardware events
such as an edge on the IRQ pin or a timer-overflow event. The debug module can also generate an SWI
under certain circumstances.
If an event occurs in an enabled interrupt source, an associated read-only status flag will become set. The
CPU will not respond until and unless the local interrupt enable is a logic 1 to enable the interrupt. The
I bit in the CCR is 0 to allow interrupts. The global interrupt mask (I bit) in the CCR is initially set after
reset which masks (prevents) all maskable interrupt sources. The user program initializes the stack pointer
and performs other system setup before clearing the I bit to allow the CPU to respond to interrupts.
When the CPU receives a qualified interrupt request, it completes the current instruction before responding
to the interrupt. The interrupt sequence obeys the same cycle-by-cycle sequence as the SWI instruction and
consists of:
•
•
•
•
Saving the CPU registers on the stack
Setting the I bit in the CCR to mask further interrupts
Fetching the interrupt vector for the highest-priority interrupt that is currently pending
Filling the instruction queue with the first three bytes of program information starting from the
address fetched from the interrupt vector locations
While the CPU is responding to the interrupt, the I bit is automatically set to avoid the possibility of another
interrupt interrupting the ISR itself (this is called nesting of interrupts). Normally, the I bit is restored to 0
when the CCR is restored from the value stacked on entry to the ISR. In rare cases, the I bit may be cleared
inside an ISR (after clearing the status flag that generated the interrupt) so that other interrupts can be
serviced without waiting for the first service routine to finish. This practice is not recommended for anyone
other than the most experienced programmers because it can lead to subtle program errors that are difficult
to debug.
The interrupt service routine ends with a return-from-interrupt (RTI) instruction which restores the CCR,
A, X, and PC registers to their pre-interrupt values by reading the previously saved information off the
stack.
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Chapter 5 Resets, Interrupts, and System Configuration
NOTE
For compatibility with the M68HC08, the H register is not automatically
saved and restored. It is good programming practice to push H onto the stack
at the start of the interrupt service routine (ISR) and restore it immediately
before the RTI that is used to return from the ISR.
When two or more interrupts are pending when the I bit is cleared, the highest priority source is serviced
first (see Table 5-2).
5.5.1
Interrupt Stack Frame
Figure 5-1 shows the contents and organization of a stack frame. Before the interrupt, the stack pointer
(SP) points at the next available byte location on the stack. The current values of CPU registers are stored
on the stack starting with the low-order byte of the program counter (PCL) and ending with the CCR. After
stacking, the SP points at the next available location on the stack which is the address that is one less than
the address where the CCR was saved. The PC value that is stacked is the address of the instruction in the
main program that would have executed next if the interrupt had not occurred.
UNSTACKING
ORDER
TOWARD LOWER ADDRESSES
7
0
SP AFTER
INTERRUPT STACKING
5
1
4
2
ACCUMULATOR
3
3
INDEX REGISTER (LOW BYTE X)*
2
4
PROGRAM COUNTER HIGH
1
5
PROGRAM COUNTER LOW
STACKING
ORDER
CONDITION CODE REGISTER
SP BEFORE
THE INTERRUPT
TOWARD HIGHER ADDRESSES
* High byte (H) of index register is not automatically stacked.
Figure 5-1. Interrupt Stack Frame
When an RTI instruction is executed, these values are recovered from the stack in reverse order. As part of
the RTI sequence, the CPU fills the instruction pipeline by reading three bytes of program information,
starting from the PC address recovered from the stack.
The status flag causing the interrupt must be acknowledged (cleared) before returning from the ISR.
Typically, the flag should be cleared at the beginning of the ISR so that if another interrupt is generated by
this same source, it will be registered so it can be serviced after completion of the current ISR.
5.5.2
External Interrupt Request (IRQ) Pin
External interrupts are managed by the IRQ status and control register, IRQSC. When the IRQ function is
enabled, synchronous logic monitors the pin for edge-only or edge-and-level events. When the MCU is in
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Chapter 5 Resets, Interrupts, and System Configuration
stop mode and system clocks are shut down, a separate asynchronous path is used so the IRQ (if enabled)
can wake the MCU.
5.5.2.1
IRQ Pin Configuration Options
The IRQ pin enable (IRQPE) control bit in IRQSC must be 1 in order for the IRQ pin to act as the interrupt
request (IRQ) input. As an IRQ input, the user can choose the polarity of edges or levels detected
(IRQEDG), whether the pin detects edges-only or edges and levels (IRQMOD), and whether an event
causes an interrupt or only sets the IRQF flag which can be polled by software.
The IRQ pin, when enabled, defaults to use an internal pull device (IRQPDD = 0), the device is a pull-up
or pull-down depending on the polarity chosen. If the user desires to use an external pull-up or pull-down,
the IRQPDD can be written to a 1 to turn off the internal device.
BIH and BIL instructions may be used to detect the level on the IRQ pin when the pin is configured to act
as the IRQ input.
NOTE
This pin does not contain a clamp diode to VDD and should not be driven
above VDD. The voltage measured on the internally pulled up IRQ pin may
be as low as VDD – 0.7 V. The internal gates connected to this pin are pulled
all the way to VDD.
NOTE
When enabling the IRQ pin for use, the IRQF will be set, and should be
cleared prior to enabling the interrupt. When configuring the pin for falling
edge and level sensitivity in a 5V system, it is necessary to wait at least 6
cycles between clearing the flag and enabling the interrupt.
5.5.2.2
Edge and Level Sensitivity
The IRQMOD control bit reconfigures the detection logic so it detects edge events and pin levels. In the
edge and level detection mode, the IRQF status flag becomes set when an edge is detected (when the IRQ
pin changes from the deasserted to the asserted level), but the flag is continuously set (and cannot be
cleared) as long as the IRQ pin remains at the asserted level.
5.5.3
Interrupt Vectors, Sources, and Local Masks
Table 5-2 provides a summary of all interrupt sources. Higher-priority sources are located toward the
bottom of the table. The high-order byte of the address for the interrupt service routine is located at the
first address in the vector address column, and the low-order byte of the address for the interrupt service
routine is located at the next higher address.
When an interrupt condition occurs, an associated flag bit becomes set. If the associated local interrupt
enable is 1, an interrupt request is sent to the CPU. Within the CPU, if the global interrupt mask (I bit in
the CCR) is 0, the CPU will finish the current instruction, stack the PCL, PCH, X, A, and CCR CPU
registers, set the I bit, and then fetch the interrupt vector for the highest priority pending interrupt.
Processing then continues in the interrupt service routine.
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Table 5-2. Vector Summary
Vector
Priority
Vector
No.
Address
(High/Low)
Lower
29 –
31
28
27
26
25
0xFFC0/FFC1 –
0xFFC4/0xFFC5
0xFFC6/FFC7
0xFFC8/FFC9
0xFFCA/FFCB
0xFFCC/FFCD
Vtpm3ovf
Vtpm3ch1
Vtpm3ch0
Vrti
24
23
22
21
0xFFCE/FFCF
0xFFD0/FFD1
0xFFD2/FFD3
0xFFD4/FFD5
Viic1
Vadc1
Vkeyboard 1
Vsci2tx
TPM3
TPM3
TPM3
System
control
IIC1
ADC1
KBI
SCI2
20
0xFFD6/FFD7
Vsci2rx
SCI2
19
0xFFD8/FFD9
Vsci2err
SCI2
18
0xFFDA/FFDB
Vsci1tx
SCI1
17
0xFFDC/FFDD
Vsci1rx
SCI1
16
0xFFDE/FFDF
Vsci1err
SCI1
15
0xFFE0/FFE1
Vspi1
SPI1
14
13
12
11
10
9
8
7
6
5
4
0xFFE2/FFE3
0xFFE4/FFE5
0xFFE6/FFE7
0xFFE8/FFE9
0xFFEA/FFEB
0xFFEC/FFED
0xFFEE/FFEF
0xFFF0/FFF1
0xFFF2/FFF3
0xFFF4/FFF5
0xFFF6/FFF7
Vtpm2ovf
Vtpm2ch1
Vtpm2ch0
Vtpm1ovf
TPM2
TPM2
TPM2
TPM1
Vtpm1ch3
Vtpm1ch2
Vtpm1ch1
Vtpm1ch0
Vicg
TPM1
TPM1
TPM1
TPM1
ICG
3
0xFFF8/FFF9
Vlvd
2
1
0xFFFA/FFFB
0xFFFC/FFFD
Virq
Vswi
System
control
IRQ
Core
0
0xFFFE/FFFF
Vreset
Higher
Vector Name
Module
System
control
Source
Enable
Description
Unused vector space
(available for user program)
TOF
TOIE
CH1F
CH1IE
CH0F
CH0IF
RTIF
RTIE
TPM3 overflow
TPM3 channel 1
TPM3 channel 0
Real-time interrupt
IICIF
IICIE
COCO
AIEN
KBF
KBIE
TDRE
TIE
TC
TCIE
IDLE
ILIE
RDRF
RIE
ORIE
OR
NFIE
NF
FEIE
FE
PFIE
PF
TDRE
TIE
TC
TCIE
IDLE
ILIE
RDRF
RIE
ORIE
OR
NFIE
NF
FEIE
FE
PFIE
PF
SPIE
SPIF
SPIE
MODF
SPTIE
SPTEF
TOF
TOIE
CH1F
CH1IE
CH0F
CH0IE
TOF
TOIE
Unused vector space
Unused vector space
CH3F
CH3IE
CH2F
CH2IE
CH1F
CH1IE
CH0F
CH0IE
ICGIF
LOLRE/LOCRE
(LOLS/LOCS)
LVDF
LVDIE
IRQF
SWI
Instruction
COP
LVD
RESET pin
Illegal opcode
IIC1
ADC1
KBI pins
SCI2 transmit
SCI2 receive
SCI2 error
SCI1 transmit
SCI1 receive
SCI1 error
SPI1
TPM2 overflow
TPM2 channel 1
TPM2 channel 0
TPM1 overflow
TPM1 channel 3
TPM1 channel 2
TPM1 channel 1
TPM1 channel 0
ICG
Low-voltage detect
IRQIE
—
IRQ pin
Software interrupt
COPE
LVDRE
—
—
Watchdog timer
Low-voltage detect
External pin
Illegal opcode
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5.6
Low-Voltage Detect (LVD) System
The MC9S08AC16 Series includes a system to protect against low voltage conditions in order to protect
memory contents and control MCU system states during supply voltage variations. The system is
comprised of a power-on reset (POR) circuit and an LVD circuit with a user selectable trip voltage, either
high (VLVDH) or low (VLVDL). The LVD circuit is enabled when LVDE in SPMSC1 is high and the trip
voltage is selected by LVDV in SPMSC2. The LVD is disabled upon entering any of the stop modes unless
the LVDSE bit is set. If LVDSE and LVDE are both set, then the MCU cannot enter stop2, and the current
consumption in stop3 with the LVD enabled will be greater.
5.6.1
Power-On Reset Operation
When power is initially applied to the MCU, or when the supply voltage drops below the VPOR level, the
POR circuit will cause a reset condition. As the supply voltage rises, the LVD circuit will hold the chip in
reset until the supply has risen above the VLVDL level. Both the POR bit and the LVD bit in SRS are set
following a POR.
5.6.2
LVD Reset Operation
The LVD can be configured to generate a reset upon detection of a low voltage condition by setting
LVDRE to 1. After an LVD reset has occurred, the LVD system will hold the MCU in reset until the supply
voltage has risen above the level determined by LVDV. The LVD bit in the SRS register is set following
either an LVD reset or POR.
5.6.3
LVD Interrupt Operation
When a low voltage condition is detected and the LVD circuit is configured for interrupt operation (LVDE
set, LVDIE set, and LVDRE clear), then LVDF will be set and an LVD interrupt will occur.
5.6.4
Low-Voltage Warning (LVW)
The LVD system has a low voltage warning flag to indicate to the user that the supply voltage is
approaching, but is still above, the LVD voltage. The LVW does not have an interrupt associated with it.
There are two user selectable trip voltages for the LVW, one high (VLVWH) and one low (VLVWL). The trip
voltage is selected by LVWV in SPMSC2. Setting the LVW trip voltage equal to the LVD trip voltage is
not recommended. Typical use of the LVW would be to select VLVWH and VLVDL.
5.7
Real-Time Interrupt (RTI)
The real-time interrupt function can be used to generate periodic interrupts. The RTI can accept two
sources of clocks, the 1-kHz internal clock or an external clock if available. The 1-kHz internal clock
source is completely independent of any bus clock source and is used only by the RTI module and, on some
MCUs, the COP watchdog. To use an external clock source, it must be available and active. The RTICLKS
bit in SRTISC is used to select the RTI clock source.
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Either RTI clock source can be used when the MCU is in run, wait or stop3 mode. When using the external
oscillator in stop3, it must be enabled in stop (OSCSTEN = 1) and configured for low bandwidth operation
(RANGE = 0). Only the internal 1-kHz clock source can be selected to wake the MCU from stop2 mode.
The SRTISC register includes a read-only status flag, a write-only acknowledge bit, and a 3-bit control
value (RTIS2:RTIS1:RTIS0) used to disable the clock source to the real-time interrupt or select one of
seven wakeup periods. The RTI has a local interrupt enable, RTIE, to allow masking of the real-time
interrupt. The RTI can be disabled by writing each bit of RTIS to zeroes, and no interrupts will be
generated. See Section 5.9.7, “System Real-Time Interrupt Status and Control Register (SRTISC),” for
detailed information about this register.
5.8
MCLK Output
The PTC2 pin is shared with the MCLK clock output. Setting the pin enable bit, MPE, causes the PTC2
pin to output a divided version of the internal MCU bus clock. The divide ratio is determined by the
MCSEL bits. When MPE is set, the PTC2 pin is forced to operate as an output pin regardless of the state
of the port data direction control bit for the pin. If the MCSEL bits are all 0s, the pin is driven low. The
slew rate and drive strength for the pin are controlled by PTCSE2 and PTCDS2, respectively. The
maximum clock output frequency is limited if slew rate control is enabled, see the electrical chapter for
pin rise and fall times with slew rate enabled.
5.9
Reset, Interrupt, and System Control Registers and Control Bits
One 8-bit register in the direct page register space and eight 8-bit registers in the high-page register space
are related to reset and interrupt systems.
Refer to the direct-page register summary in Chapter 4, “Memory,” of this data sheet for the absolute
address assignments for all registers. This section refers to registers and control bits only by their names.
A Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
Some control bits in the SOPT and SPMSC2 registers are related to modes of operation. Although brief
descriptions of these bits are provided here, the related functions are discussed in greater detail in
Chapter 3, “Modes of Operation.”
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5.9.1
Interrupt Pin Request Status and Control Register (IRQSC)
This direct page register includes status and control bits which are used to configure the IRQ function,
report status, and acknowledge IRQ events.
7
R
6
5
4
IRQPDD
IRQEDG
IRQPE
0
3
2
IRQF
0
W
Reset
1
0
IRQIE
IRQMOD
0
0
IRQACK
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 5-2. Interrupt Request Status and Control Register (IRQSC)
Table 5-3. IRQSC Register Field Descriptions
Field
Description
6
IRQPDD
Interrupt Request (IRQ) Pull Device Disable— This read/write control bit is used to disable the internal
pull-up/pull-down device when the IRQ pin is enabled (IRQPE = 1) allowing for an external device to be used.
0 IRQ pull device enabled if IRQPE = 1.
1 IRQ pull device disabled if IRQPE = 1.
5
IRQEDG
Interrupt Request (IRQ) Edge Select — This read/write control bit is used to select the polarity of edges or
levels on the IRQ pin that cause IRQF to be set. The IRQMOD control bit determines whether the IRQ pin is
sensitive to both edges and levels or only edges. When the IRQ pin is enabled as the IRQ input and is configured
to detect rising edges, it has a pull-down. When the IRQ pin is enabled as the IRQ input and is configured to
detect falling edges, it has a pull-up.
0 IRQ is falling edge or falling edge/low-level sensitive.
1 IRQ is rising edge or rising edge/high-level sensitive.
4
IRQPE
IRQ Pin Enable — This read/write control bit enables the IRQ pin function. When this bit is set the IRQ pin can
be used as an interrupt request.
0 IRQ pin function is disabled.
1 IRQ pin function is enabled.
3
IRQF
2
IRQACK
1
IRQIE
0
IRQMOD
IRQ Flag — This read-only status bit indicates when an interrupt request event has occurred.
0 No IRQ request.
1 IRQ event detected.
IRQ Acknowledge — This write-only bit is used to acknowledge interrupt request events (write 1 to clear IRQF).
Writing 0 has no meaning or effect. Reads always return 0. If edge-and-level detection is selected (IRQMOD = 1),
IRQF cannot be cleared while the IRQ pin remains at its asserted level.
IRQ Interrupt Enable — This read/write control bit determines whether IRQ events generate an interrupt
request.
0 Interrupt request when IRQF set is disabled (use polling).
1 Interrupt requested whenever IRQF = 1.
IRQ Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. The IRQEDG control bit determines the polarity of edges and levels that are detected as interrupt
request events. See Section 5.5.2.2, “Edge and Level Sensitivity” for more details.
0 IRQ event on falling edges or rising edges only.
1 IRQ event on falling edges and low levels or on rising edges and high levels.
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5.9.2
System Reset Status Register (SRS)
This register includes seven read-only status flags to indicate the source of the most recent reset. When a
debug host forces reset by writing 1 to BDFR in the SBDFR register, none of the status bits in SRS will be
set. Writing any value to this register address clears the COP watchdog timer without affecting the contents
of this register. The reset state of these bits depends on what caused the MCU to reset.
R
7
6
5
4
3
2
1
0
POR
PIN
COP
ILOP
ILAD
ICG
LVD
0
W
Writing any value to SRS address clears COP watchdog timer.
POR
1
0
0
0
0
0
1
0
LVR:
U
0
0
0
0
0
1
0
Any other
reset:
0
Note(1)
Note(1)
Note(1)
0
Note(1)
0
0
U = Unaffected by reset
1
Any of these reset sources that are active at the time of reset will cause the corresponding bit(s) to be set; bits corresponding
to sources that are not active at the time of reset will be cleared.
Figure 5-3. System Reset Status (SRS)
Table 5-4. SRS Register Field Descriptions
Field
Description
7
POR
Power-On Reset — Reset was caused by the power-on detection logic. Because the internal supply voltage was
ramping up at the time, the low-voltage reset (LVR) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVR threshold.
0 Reset not caused by POR.
1 POR caused reset.
6
PIN
External Reset Pin — Reset was caused by an active-low level on the external reset pin.
0 Reset not caused by external reset pin.
1 Reset came from external reset pin.
5
COP
Computer Operating Properly (COP) Watchdog — Reset was caused by the COP watchdog timer timing out.
This reset source may be blocked by COPE = 0.
0 Reset not caused by COP timeout.
1 Reset caused by COP timeout.
4
ILOP
Illegal Opcode — Reset was caused by an attempt to execute an unimplemented or illegal opcode. The STOP
instruction is considered illegal if stop is disabled by STOPE = 0 in the SOPT register. The BGND instruction is
considered illegal if active background mode is disabled by ENBDM = 0 in the BDCSC register.
0 Reset not caused by an illegal opcode.
1 Reset caused by an illegal opcode.
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Table 5-4. SRS Register Field Descriptions (continued)
Field
3
ILAD
Description
Illegal Address — Reset was caused by an attempt to access a designated illegal address.
0 Reset not caused by an illegal address access.
1 Reset caused by an illegal address access.
Illegal address areas in the MC9S08AC16 are:
0x0470 - 0x17FF — Gap from end of RAM to start of high page registers
0x1860 - 0xBFFF — Gap from end of high page registers to start of Flash memory
Unused and reserved locations in register areas are not considered illegal addresses and do not trigger illegal
address resets.
2
ICG
Internal Clock Generation Module Reset — Reset was caused by an ICG module reset.
0 Reset not caused by ICG module.
1 Reset caused by ICG module.
1
LVD
Low Voltage Detect — If the LVDRE and LVDSE bits are set and the supply drops below the LVD trip voltage,
an LVD reset will occur. This bit is also set by POR.
0 Reset not caused by LVD trip or POR.
1 Reset caused by LVD trip or POR.
5.9.3
System Background Debug Force Reset Register (SBDFR)
This register contains a single write-only control bit. A serial background command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
BDFR1
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
1
BDFR is writable only through serial background debug commands, not from user programs.
Figure 5-4. System Background Debug Force Reset Register (SBDFR)
Table 5-5. SBDFR Register Field Descriptions
Field
Description
0
BDFR
Background Debug Force Reset — A serial background command such as WRITE_BYTE may be used to
allow an external debug host to force a target system reset. Writing logic 1 to this bit forces an MCU reset. This
bit cannot be written from a user program.
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
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Chapter 5 Resets, Interrupts, and System Configuration
5.9.4
System Options Register (SOPT)
This register may be read at any time. Bits 3 and 2 are unimplemented and always read 0. This is a
write-once register so only the first write after reset is honored. Any subsequent attempt to write to SOPT
(intentionally or unintentionally) is ignored to avoid accidental changes to these sensitive settings. SOPT
should be written during the user’s reset initialization program to set the desired controls even if the desired
settings are the same as the reset settings.
7
6
5
COPE
COPT
STOPE
1
1
0
4
R
3
2
0
0
0
0
1
0
1
1
W
Reset
1
= Unimplemented or Reserved
Figure 5-5. System Options Register (SOPT)
Table 5-6. SOPT Register Field Descriptions
Field
Description
7
COPE
COP Watchdog Enable — This write-once bit defaults to 1 after reset.
0 COP watchdog timer disabled.
1 COP watchdog timer enabled (force reset on timeout).
6
COPT
COP Watchdog Timeout — This write-once bit defaults to 1 after reset.
0 Short timeout period selected.
1 Long timeout period selected.
5
STOPE
Stop Mode Enable — This write-once bit defaults to 0 after reset, which disables stop mode. If stop mode is
disabled and a user program attempts to execute a STOP instruction, an illegal opcode reset is forced.
0 Stop mode disabled.1Stop mode enabled.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 5 Resets, Interrupts, and System Configuration
5.9.5
System MCLK Control Register (SMCLK)
This register is used to control the MCLK clock output.
R
7
6
5
0
0
0
4
3
2
1
0
0
MPE
MCSEL
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 5-6. System MCLK Control Register (SMCLK)
Table 5-7. SMCLK Register Field Descriptions
Field
4
MPE
2:0
MCSEL
Description
MCLK Pin Enable — This bit is used to enable the MCLK function.
0 MCLK output disabled.
1 MCLK output enabled on PTC2 pin.
MCLK Divide Select — These bits are used to select the divide ratio for the MCLK output according to the
formula below when the MCSEL bits are not equal to all zeroes. In the case that the MCSEL bits are all zero and
MPE is set, the pin is driven low. See Equation 5-1.
MCLK frequency = Bus Clock frequency ÷ (2 * MCSEL)
Eqn. 5-1
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
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Chapter 5 Resets, Interrupts, and System Configuration
5.9.6
System Device Identification Register (SDIDH, SDIDL)
This read-only register is included so host development systems can identify the HCS08 derivative and
revision number. This allows the development software to recognize where specific memory blocks,
registers, and control bits are located in a target MCU.
7
6
5
4
R
3
2
1
0
ID11
ID10
ID9
ID8
0
0
0
0
W
Reset
—
—
—
—
= Unimplemented or Reserved
Figure 5-7. System Device Identification Register — High (SDIDH)
Table 5-8. SDIDH Register Field Descriptions
Field
7:4
Reserved
3:0
ID[11:8]
R
Description
Bits 7:4 are reserved. Reading these bits will result in an indeterminate value; writes have no effect.
Part Identification Number — Each derivative in the HCS08 Family has a unique identification number. The
MC9S08AC16 Series is hard coded to the value 0x012. See also ID bits in Table 5-9.
7
6
5
4
3
2
1
0
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0
0
0
1
0
0
1
0
W
Reset
= Unimplemented or Reserved
Figure 5-8. System Device Identification Register — Low (SDIDL)
Table 5-9. SDIDL Register Field Descriptions
Field
7:0
ID[7:0]
Description
Part Identification Number — Each derivative in the HCS08 Family has a unique identification number. The
MC9S08AC16 Series is hard coded to the value 0x012. See also ID bits in Table 5-8.
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Chapter 5 Resets, Interrupts, and System Configuration
5.9.7
System Real-Time Interrupt Status and Control Register (SRTISC)
This register contains one read-only status flag, one write-only acknowledge bit, three read/write delay
selects, and three unimplemented bits, which always read 0.
R
7
6
RTIF
0
W
5
4
RTICLKS
RTIE
0
0
3
2
1
0
RTIS2
RTIS1
RTIS0
0
0
0
0
RTIACK
Reset
0
0
0
= Unimplemented or Reserved
Figure 5-9. System RTI Status and Control Register (SRTISC)
Table 5-10. SRTISC Register Field Descriptions
Field
Description
7
RTIF
Real-Time Interrupt Flag — This read-only status bit indicates the periodic wakeup timer has timed out.
0 Periodic wakeup timer not timed out.
1 Periodic wakeup timer timed out.
6
RTIACK
Real-Time Interrupt Acknowledge — This write-only bit is used to acknowledge real-time interrupt request
(write 1 to clear RTIF). Writing 0 has no meaning or effect. Reads always return logic 0.
5
RTICLKS
Real-Time Interrupt Clock Select — This read/write bit selects the clock source for the real-time interrupt.
0 Real-time interrupt request clock source is internal 1-kHz oscillator.
1 Real-time interrupt request clock source is external clock.
4
RTIE
Real-Time Interrupt Enable — This read-write bit enables real-time interrupts.
0 Real-time interrupts disabled.
1 Real-time interrupts enabled.
2:0
RTIS[2:0]
Real-Time Interrupt Delay Selects — These read/write bits select the wakeup delay for the RTI. The clock
source for the real-time interrupt is a self-clocked source which oscillates at about 1 kHz, is independent of other
MCU clock sources. Using external clock source the delays will be crystal frequency divided by value in
RTIS2:RTIS1:RTIS0. See Table 5-11.
Table 5-11. Real-Time Interrupt Frequency
1
RTIS2:RTIS1:RTIS0
1-kHz Clock Source Delay1
Using External Clock Source Delay
(Crystal Frequency)
0:0:0
Disable periodic wakeup timer
Disable periodic wakeup timer
0:0:1
8 ms
divide by 256
0:1:0
32 ms
divide by 1024
0:1:1
64 ms
divide by 2048
1:0:0
128 ms
divide by 4096
1:0:1
256 ms
divide by 8192
1:1:0
512 ms
divide by 16384
1:1:1
1.024 s
divide by 32768
Normal values are shown in this column based on fRTI = 1 kHz. See Appendix A, “Electrical Characteristics and Timing
Specifications,” fRTI for the tolerance on these values.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
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Chapter 5 Resets, Interrupts, and System Configuration
5.9.8
R
System Power Management Status and Control 1 Register (SPMSC1)
7
6
LVDF
0
W
Reset
5
4
3
2
LVDIE
LVDRE(2)
LVDSE(2)
LVDE(2)
0
1
1
1
1
1
0
BGBE
LVDACK
0
0
0
0
= Unimplemented or Reserved
1
2
Bit 1 is a reserved bit that must always be written to 0.
This bit can be written only one time after reset. Additional writes are ignored.
Figure 5-10. System Power Management Status and Control 1 Register (SPMSC1)
Table 5-12. SPMSC1 Register Field Descriptions
Field
Description
7
LVDF
Low-Voltage Detect Flag — Provided LVDE = 1, this read-only status bit indicates a low-voltage detect event.
6
LVDACK
Low-Voltage Detect Acknowledge — This write-only bit is used to acknowledge low voltage detection errors
(write 1 to clear LVDF). Reads always return 0.
5
LVDIE
Low-Voltage Detect Interrupt Enable — This read/write bit enables hardware interrupt requests for LVDF.
0 Hardware interrupt disabled (use polling).
1 Request a hardware interrupt when LVDF = 1.
4
LVDRE
Low-Voltage Detect Reset Enable — This read/write bit enables LVDF events to generate a hardware reset
(provided LVDE = 1).
0 LVDF does not generate hardware resets.
1 Force an MCU reset when LVDF = 1.
3
LVDSE
Low-Voltage Detect Stop Enable — Provided LVDE = 1, this read/write bit determines whether the low-voltage
detect function operates when the MCU is in stop mode.
0 Low-voltage detect disabled during stop mode.
1 Low-voltage detect enabled during stop mode.
2
LVDE
Low-Voltage Detect Enable — This read/write bit enables low-voltage detect logic and qualifies the operation
of other bits in this register.
0 LVD logic disabled.
1 LVD logic enabled.
0
BGBE
Bandgap Buffer Enable — The BGBE bit is used to enable an internal buffer for the bandgap voltage reference
for use by the ADC module on one of its internal channels.
0 Bandgap buffer disabled.
1 Bandgap buffer enabled.
MC9S08AC16 Series Data Sheet, Rev. 0
78
PRELIMINARY
Freescale Semiconductor
Chapter 5 Resets, Interrupts, and System Configuration
5.9.9
System Power Management Status and Control 2 Register (SPMSC2)
This register is used to report the status of the low voltage warning function, and to configure the stop mode
behavior of the MCU.
R
7
6
LVWF
0
W
5
4
LVDV
LVWV
3
2
PPDF
0
LVWACK
1
0
PPDC1
PPDACK
Power-on
reset:
0(2)
0
0
0
0
0
0
0
LVD
reset:
0(2)
0
U
U
0
0
0
0
Any other
reset:
0(2)
0
U
U
0
0
0
0
= Unimplemented or Reserved
1
2
U = Unaffected by reset
This bit can be written only one time after reset. Additional writes are ignored.
LVWF will be set in the case when VSupply transitions below the trip point or after reset and VSupply is already below VLVW.
Figure 5-11. System Power Management Status and Control 2 Register (SPMSC2)
Table 5-13. SPMSC2 Register Field Descriptions
Field
7
LVWF
6
LVWACK
Description
Low-Voltage Warning Flag — The LVWF bit indicates the low voltage warning status.
0 Low voltage warning not present.
1 Low voltage warning is present or was present.
Low-Voltage Warning Acknowledge — The LVWACK bit is the low-voltage warning acknowledge.
Writing a 1 to LVWACK clears LVWF to a 0 if a low voltage warning is not present.
5
LVDV
Low-Voltage Detect Voltage Select — The LVDV bit selects the LVD trip point voltage (VLVD).
0 Low trip point selected (VLVD = VLVDL).
1 High trip point selected (VLVD = VLVDH).
4
LVWV
Low-Voltage Warning Voltage Select — The LVWV bit selects the LVW trip point voltage (VLVW).
0 Low trip point selected (VLVW = VLVWL).
1 High trip point selected (VLVW = VLVWH).
3
PPDF
Partial Power Down Flag — The PPDF bit indicates that the MCU has exited the stop2 mode.
0 Not stop2 mode recovery.
1 Stop2 mode recovery.
2
PPDACK
0
PPDC
Partial Power Down Acknowledge — Writing a 1 to PPDACK clears the PPDF bit.
Partial Power Down Control — The write-once PPDC bit controls whether stop2 or stop3 mode is selected.
0 Stop3 mode enabled.
1 Stop2, partial power down, mode enabled.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
79
Chapter 5 Resets, Interrupts, and System Configuration
5.9.10
System Options Register 2 (SOPT2)
This high page register contains bits to configure MCU specific features on the MC9S08AC16 Series
devices.
7
R
COPCLKS1
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
W
Reset:
1
= Unimplemented or Reserved
Figure 5-12. System Options Register 2 (SOPT2)
1
This bit can be written only one time after reset. Additional writes are ignored.
Table 5-14. SOPT2 Register Field Descriptions
Field
7
COPCLKS
Description
COP Watchdog Clock Select — This write-once bit selects the clock source of the COP watchdog.
0 Internal 1-kHz clock is source to COP.
1 Bus clock is source to COP.
MC9S08AC16 Series Data Sheet, Rev. 0
80
PRELIMINARY
Freescale Semiconductor
Chapter 6
Parallel Input/Output
6.1
Introduction
This chapter explains software controls related to parallel input/output (I/O). The MC9S08AC16 has seven
I/O ports which include a total of 54 general-purpose I/O pins. See Chapter 2, “Pins and Connections” for
more information about the logic and hardware aspects of these pins.
Many of these pins are shared with on-chip peripherals such as timer systems, communication systems, or
keyboard interrupts. When these other modules are not controlling the port pins, they revert to
general-purpose I/O control.
NOTE
Not all general-purpose I/O pins are available on all packages. To avoid
extra current drain from floating input pins, the user’s reset initialization
routine in the application program should either enable on-chip pullup
devices or change the direction of unconnected pins to outputs so the pins
do not float.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
81
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1/AD1P
PTB0/TPM3CH0/AD1P
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 6 Parallel Input/Output
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
2 KBIP6–KBIP5
5 KBIP4–KBIP0
PORT D
LVD
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
IRQ
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, 42-, or 44-pin packages
= Not available on 32- or 42-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 6-1. Block Diagram Highlighting Parallel Input/Output Pins
MC9S08AC16 Series Data Sheet, Rev. 0
82
PRELIMINARY
Freescale Semiconductor
Chapter 6 Parallel Input/Output
6.2
Features
Parallel I/O and Pin Control features, depending on package choice, include:
• A total of 38 general-purpose I/O pins in seven ports
• Hysteresis input buffers
• Software-controlled pullups on each input pin
• Software-controlled slew rate output buffers
• Four port A pins
• Four port B pins shared with ADC1 and TPM31
• Six port C pins shared with SCI2, IIC1, and MCLK
• Four port D pins shared with ADC1, KBI, and TPM1 and TPM2 external clock inputs
• Eight port E pins shared with SCI1, TPM1, and SPI1
• Five port F pins shared with TPM1 and TPM2
• Seven port G pins shared with XTAL, EXTAL, and KBI
6.3
Pin Descriptions
The MC9S08AC16 Series has a total of 38 parallel I/O pins in seven ports (PTA–PTG). Not all pins are
bonded out in all packages. Consult the pin assignment in Chapter 2, “Pins and Connections,” for available
parallel I/O pins. All of these pins are available for general-purpose I/O when they are not used by other
on-chip peripheral systems.
After reset, the shared peripheral functions are disabled so that the pins are controlled by the parallel I/O.
All of the parallel I/O are configured as inputs (PTxDDn = 0). The pin control functions for each pin are
configured as follows: slew rate control enabled (PTxSEn = 1), low drive strength selected (PTxDSn = 0),
and internal pullups disabled (PTxPEn = 0).
The following paragraphs discuss each port and the software controls that determine each pin’s use.
6.3.1
Port A
Port A
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTA7
R
R
R
R
PTA2
PTA1
PTA0
Figure 6-2. Port A Pin Names
Port A pins are general-purpose I/O pins. Parallel I/O function is controlled by the port A data (PTAD) and
data direction (PTADD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTAPE), slew rate control (PTASE), and drive strength select (PTADS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
1. TPM3 is not available on S9S08AWxxA devices.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
83
Chapter 6 Parallel Input/Output
6.3.2
Port B
Port B
MCU Pin:
Bit 7
6
5
4
R
R
R
R
3
2
PTB3/
PTB2/
TPM3CH0/ TPM3CH1/
AD1P3
AD1P2
1
Bit 0
PTB1/
AD1P1
PTB0/
AD1P0
Figure 6-3. Port B Pin Names
Port B pins are general-purpose I/O pins. Parallel I/O function is controlled by the port B data (PTBD) and
data direction (PTBDD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTBPE), slew rate control (PTBSE), and drive strength select (PTBDS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
Port B general-purpose I/O are shared with the ADC and TPM3 timer channels. Any pin enabled as an
ADC input will have the general-purpose I/O function disabled. When any TPM3 function is enabled, the
direction (input or output) is controlled by the TPM3 and not by the data direction register of the parallel
I/O port. Refer to Chapter 10, “Timer/PWM (S08TPMV3),” for more information about using port B pins
as TPM channels. Refer to Chapter 14, “Analog-to-Digital Converter (S08ADC10V1)” for more
information about using port B as analog inputs.
6.3.3
Port C
Port C
MCU Pin:
Bit 7
6
5
3
3
2
1
Bit 0
0
R
PTC5/
RxD2
PTC4
PTC3/
TxD2
PTC2/
MCLK
PTC1/
SDA1
PTC0/
SCL1
Figure 6-4. Port C Pin Names
Port C pins are general-purpose I/O pins. Parallel I/O function is controlled by the port C data (PTCD) and
data direction (PTCDD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTCPE), slew rate control (PTCSE), and drive strength select (PTCDS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
Port C general-purpose I/O is shared with SCI2, IIC, and MCLK. When any shared function is enabled,
the direction, input or output, is controlled by the shared function and not by the data direction register of
the parallel I/O port. Also, for pins which are configured as outputs by the shared function, the output data
is controlled by the shared function and not by the port data register.
Refer to Chapter 11, “Serial Communications Interface (S08SCIV4)” for more information about using
port C pins as SCI pins.
Refer to Chapter 13, “Inter-Integrated Circuit (S08IICV2)” for more information about using port C pins
as IIC pins.
Refer to Chapter 5, “Resets, Interrupts, and System Configuration” for more information about using
PTC2 as the MCLK pin.
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Chapter 6 Parallel Input/Output
6.3.4
Port D
Port D
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
R
R
R
R
PTD3/
AD1P11/
KBIP6
PTD2/
AD1P10/
KBIP5
PTD1/
AD1P9
PTD0/
AD1P8
Figure 6-5. Port D Pin Names
Port D pins are general-purpose I/O pins. Parallel I/O function is controlled by the port D data (PTDD) and
data direction (PTDDD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTDPE), slew rate control (PTDSE), and drive strength select (PTDDS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
Port D general-purpose I/O are shared with the ADC and KBI. When any of these shared functions is
enabled, the direction, input or output, is controlled by the shared function and not by the data direction
register of the parallel I/O port. When a pin is shared with both the ADC and a digital peripheral function,
the ADC has higher priority. For example, in the case that both the ADC and the KBI are configured to use
PTD7 then the pin is controlled by the ADC module.
Refer to Chapter 10, “Timer/PWM (S08TPMV3)” for more information about using port D pins as TPM
external clock inputs.
Refer to Chapter 14, “Analog-to-Digital Converter (S08ADC10V1)” for more information about using
port D pins as analog inputs.
Refer to Chapter 9, “Keyboard Interrupt (S08KBIV1)” for more information about using port D pins as
keyboard inputs.
6.3.5
Port E
Port E
MCU Pin:
Bit 7
6
5
4
PTE7/
SPSCK1
PTE6/
MOSI1
PTE5/
MISO1
PTE4/
SS1
3
2
PTE3/
PTE2/
TPM1CH1 TPM1CH0
1
Bit 0
PTE1/
RxD1
PTE0/
TxD1
Figure 6-6. Port E Pin Names
Port E pins are general-purpose I/O pins. Parallel I/O function is controlled by the port E data (PTED) and
data direction (PTEDD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTEPE), slew rate control (PTESE), and drive strength select (PTEDS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
Port E general-purpose I/O is shared with SCI1, SPI, and TPM1 timer channels. When any of these shared
functions is enabled, the direction, input or output, is controlled by the shared function and not by the data
direction register of the parallel I/O port. Also, for pins which are configured as outputs by the shared
function, the output data is controlled by the shared function and not by the port data register.
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Refer to Chapter 11, “Serial Communications Interface (S08SCIV4)” for more information about using
port E pins as SCI pins.
Refer to Chapter 12, “Serial Peripheral Interface (S08SPIV3)” for more information about using port E
pins as SPI pins.
Refer to Chapter 10, “Timer/PWM (S08TPMV3)” for more information about using port E pins as TPM
channel pins.
6.3.6
Port F
Port F
MCU Pin:
Bit 7
6
5
R
PTF6
4
PTF5/
PTF4/
TPM2CH1 TPM2CH0
3
2
R
R
1
Bit 0
PTF1/
PTF0/
TPM1CH3 TPM1CH2
Figure 6-7. Port F Pin Names
Port F pins are general-purpose I/O pins. Parallel I/O function is controlled by the port F data (PTFD) and
data direction (PTFDD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTFPE), slew rate control (PTFSE), and drive strength select (PTFDS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
Port F general-purpose I/O is shared with TPM1 and TPM2 timer channels. When any of these shared
functions is enabled, the direction, input or output, is controlled by the shared function and not by the data
direction register of the parallel I/O port. Also, for pins which are configured as outputs by the shared
function, the output data is controlled by the shared function and not by the port data register.
Refer to Chapter 10, “Timer/PWM (S08TPMV3)” for more information about using port F pins as TPM
channel pins.
6.3.7
Port G
Port G
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
0
PTG6/
EXTAL
PTG5/
XTAL
PTG4/
KBIP4
PTG3/
KBIP3
PTG2/
KBIP2
PTG1/
KBIP1
PTG0/
KBIP0
Figure 6-8. Port G Pin Names
Port G pins are general-purpose I/O pins. Parallel I/O function is controlled by the port G data (PTGD) and
data direction (PTGDD) registers which are located in page zero register space. The pin control registers,
pullup enable (PTGPE), slew rate control (PTGSE), and drive strength select (PTGDS) are located in the
high page registers. Refer to Section 6.4, “Parallel I/O Control” for more information about
general-purpose I/O control and Section 6.5, “Pin Control” for more information about pin control.
Port G general-purpose I/O is shared with KBI, XTAL, and EXTAL. When a pin is enabled as a KBI input,
the pin functions as an input regardless of the state of the associated PTG data direction register bit. When
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the external oscillator is enabled, PTG5 and PTG6 function as oscillator pins. In this case the associated
parallel I/O and pin control registers have no control of the pins.
Refer to Chapter 8, “Internal Clock Generator (S08ICGV4)” for more information about using port G pins
as XTAL and EXTAL pins.
Refer to Chapter 9, “Keyboard Interrupt (S08KBIV1)” for more information about using port G pins as
keyboard inputs.
6.4
Parallel I/O Control
Reading and writing of parallel I/O is done through the port data registers. The direction, input or output,
is controlled through the port data direction registers. The parallel I/O port function for an individual pin
is illustrated in the block diagram below.
PTxDDn
D
Output Enable
Q
PTxDn
D
Output Data
Q
1
Port Read
Data
0
Synchronizer
Input Data
BUSCLK
Figure 6-9. Parallel I/O Block Diagram
The data direction control bits determine whether the pin output driver is enabled, and they control what
is read for port data register reads. Each port pin has a data direction register bit. When PTxDDn = 0, the
corresponding pin is an input and reads of PTxD return the pin value. When PTxDDn = 1, the
corresponding pin is an output and reads of PTxD return the last value written to the port data register.
When a peripheral module or system function is in control of a port pin, the data direction register bit still
controls what is returned for reads of the port data register, even though the peripheral system has
overriding control of the actual pin direction.
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When a shared analog function is enabled for a pin, all digital pin functions are disabled. A read of the port
data register returns a value of 0 for any bits which have shared analog functions enabled. In general,
whenever a pin is shared with both an alternate digital function and an analog function, the analog function
has priority such that if both the digital and analog functions are enabled, the analog function controls the
pin.
It is a good programming practice to write to the port data register before changing the direction of a port
pin to become an output. This ensures that the pin will not be driven momentarily with an old data value
that happened to be in the port data register.
6.5
Pin Control
The pin control registers are located in the high page register block of the memory. These registers are used
to control pullups, slew rate, and drive strength for the I/O pins. The pin control registers operate
independently of the parallel I/O registers.
6.5.1
Internal Pullup Enable
An internal pullup device can be enabled for each port pin by setting the corresponding bit in one of the
pullup enable registers (PTxPEn). The pullup device is disabled if the pin is configured as an output by the
parallel I/O control logic or any shared peripheral function regardless of the state of the corresponding
pullup enable register bit. The pullup device is also disabled if the pin is controlled by an analog function.
6.5.2
Output Slew Rate Control Enable
Slew rate control can be enabled for each port pin by setting the corresponding bit in one of the slew rate
control registers (PTxSEn). When enabled, slew control limits the rate at which an output can transition in
order to reduce EMC emissions. Slew rate control has no effect on pins which are configured as inputs.
6.5.3
Output Drive Strength Select
An output pin can be selected to have high output drive strength by setting the corresponding bit in one of
the drive strength select registers (PTxDSn). When high drive is selected a pin is capable of sourcing and
sinking greater current. Even though every I/O pin can be selected as high drive, the user must ensure that
the total current source and sink limits for the chip are not exceeded. Drive strength selection is intended
to affect the DC behavior of I/O pins. However, the AC behavior is also affected. High drive allows a pin
to drive a greater load with the same switching speed as a low drive enabled pin into a smaller load.
Because of this the EMC emissions may be affected by enabling pins as high drive.
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6.6
Pin Behavior in Stop Modes
Depending on the stop mode, I/O functions differently as the result of executing a STOP instruction. An
explanation of I/O behavior for the various stop modes follows:
• Stop2 mode is a partial power-down mode, whereby I/O latches are maintained in their state as
before the STOP instruction was executed. CPU register status and the state of I/O registers should
be saved in RAM before the STOP instruction is executed to place the MCU in stop2 mode. Upon
recovery from stop2 mode, before accessing any I/O, the user should examine the state of the PPDF
bit in the SPMSC2 register. If the PPDF bit is 0, I/O must be initialized as if a power on reset had
occurred. If the PPDF bit is 1, I/O data previously stored in RAM, before the STOP instruction was
executed, peripherals may require being initialized and restored to their pre-stop condition. The
user must then write a 1 to the PPDACK bit in the SPMSC2 register. Access to I/O is now permitted
again in the user’s application program.
• In stop3 mode, all I/O is maintained because internal logic circuity stays powered up. Upon
recovery, normal I/O function is available to the user.
6.7
Parallel I/O and Pin Control Registers
This section provides information about the registers associated with the parallel I/O ports and pin control
functions. These parallel I/O registers are located in page zero of the memory map and the pin control
registers are located in the high page register section of memory.
Refer to tables in Chapter 4, “Memory,” for the absolute address assignments for all parallel I/O and pin
control registers. This section refers to registers and control bits only by their names. A Freescale-provided
equate or header file normally is used to translate these names into the appropriate absolute addresses.
6.7.1
Port A I/O Registers (PTAD and PTADD)
Port A parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTAD7
R
R
R
R
PTAD2
PTAD1
PTAD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-10. Port A Data Register (PTAD)1
1
Bits 6 through 3 are reserved bits that must always be written to 0.
Table 6-1. PTAD Register Field Descriptions
Field
Description
7, 2:0
PTADn
Port A Data Register Bits — For port A pins that are inputs, reads return the logic level on the pin. For port A
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port A pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTAD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
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7
6
5
4
3
2
1
0
PTADD7
R
R
R
R
PTADD2
PTADD1
PTADD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-11. Data Direction for Port A Register (PTADD)1
1
Bits 6 through 3 are reserved bits that must always be written to 0.
Table 6-2. PTADD Register Field Descriptions
Field
Description
7, 2:0
PTADDn
Data Direction for Port A Bits — These read/write bits control the direction of port A pins and what is read for
PTAD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port A bit n and PTAD reads return the contents of PTADn.
6.7.2
Port A Pin Control Registers (PTAPE, PTASE, PTADS)
In addition to the I/O control, port A pins are controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTAPE7
R
R
R
R
PTAPE2
PTAPE1
PTAPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-12. Internal Pullup Enable for Port A
1
(PTAPE)1
Bits 6 through 3 are reserved bits that must always be written to 0.
Table 6-3. PTADD Register Field Descriptions
Field
Description
7, 2:0
PTAPEn
Internal Pullup Enable for Port A Bits — Each of these control bits determines if the internal pullup device is
enabled for the associated PTA pin. For port A pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port A bit n.
1 Internal pullup device enabled for port A bit n.
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7
6
5
4
3
2
1
0
PTASE7
R
R
R
R
PTASE2
PTASE1
PTASE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-13. Internal Pullup Enable for Port A (PTASE)1
1
Bits 6 through 3 are reserved bits that must always be written to 0.
Table 6-4. PTASE Register Field Descriptions
Field
Description
7, 2:0
PTASEn]
Output Slew Rate Control Enable for Port A Bits — Each of these control bits determine whether output slew
rate control is enabled for the associated PTA pin. For port A pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port A bit n.
1 Output slew rate control enabled for port A bit n.
7
6
5
4
3
2
1
0
PTADS7
R
R
R
R
PTADS2
PTADS1
PTADS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-14. Internal Pullup Enable for Port A
1
(PTASE)1
Bits 6 through 3 are reserved bits that must always be written to 0.
Table 6-5. PTASE Register Field Descriptions
Field
7, 2:0
PTADSn
Description
Output Drive Strength Selection for Port A Bits — Each of these control bits selects between low and high
output drive for the associated PTA pin.
0 Low output drive enabled for port A bit n.
1 High output drive enabled for port A bit n.
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6.7.3
Port B I/O Registers (PTBD and PTBDD)
Port B parallel I/O function is controlled by the registers in this section.
7
6
5
4
3
2
1
0
R
R
R
R
PTBD3
PTBD2
PTBD1
PTBD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-15. Port B Data Register (PTBD)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-6. PTBD Register Field Descriptions
Field
Description
3:0
PTBD[3:0]
Port B Data Register Bits — For port B pins that are inputs, reads return the logic level on the pin. For port B
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port B pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTBD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
R
R
R
R
PTBDD3
PTBDD2
PTBDD1
PTBDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-16. Data Direction for Port B
1
(PTBDD)1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-7. PTBDD Register Field Descriptions
Field
Description
3:0
Data Direction for Port B Bits — These read/write bits control the direction of port B pins and what is read for
PTBDD[3:0] PTBD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port B bit n and PTBD reads return the contents of PTBDn.
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6.7.4
Port B Pin Control Registers (PTBPE, PTBSE, PTBDS)
In addition to the I/O control, port B pins are controlled by the registers listed below.
7
6
5
4
3
2
1
0
R
R
R
R
PTBPE3
PTBPE2
PTBPE1
PTBPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-17. Internal Pullup Enable for Port B (PTBPE)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-8. PTBPE Register Field Descriptions
Field
Description
3:0
Internal Pullup Enable for Port B Bits — Each of these control bits determines if the internal pullup device is
PTBPE[3:0] enabled for the associated PTB pin. For port B pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port B bit n.
1 Internal pullup device enabled for port B bit n.
7
6
5
4
3
2
1
0
R
R
R
R
PTBSE3
PTBSE2
PTBSE1
PTBSE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-18. Output Slew Rate Control Enable (PTBSE)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-9. PTBSE Register Field Descriptions
Field
Description
3:0
Output Slew Rate Control Enable for Port B Bits— Each of these control bits determine whether output slew
PTBSE[3:0] rate control is enabled for the associated PTB pin. For port B pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port B bit n.
1 Output slew rate control enabled for port B bit n.
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7
6
5
4
3
2
1
0
R
R
R
R
PTBDS3
PTBDS2
PTBDS1
PTBDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-19. Internal Pullup Enable for Port B (PTBDS)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-10. PTBDS Register Field Descriptions
Field
Description
3:0
Output Drive Strength Selection for Port B Bits — Each of these control bits selects between low and high
PTBDS[3:0] output drive for the associated PTB pin.
0 Low output drive enabled for port B bit n.
1 High output drive enabled for port B bit n.
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6.7.5
Port C I/O Registers (PTCD and PTCDD)
Port C parallel I/O function is controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
R
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-20. Port C Data Register (PTCD)1
1
Bit 6 is a reserved bit that must always be written to 0.
Table 6-11. PTCD Register Field Descriptions
Field
Description
5:0
PTCD[5:0]
Port C Data Register Bits — For port C pins that are inputs, reads return the logic level on the pin. For port C
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port C pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTCD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
R
6
5
4
3
2
1
0
R
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-21. Data Direction for Port C
1
(PTCDD)1
Bit 6 is a reserved bit that must always be written to 0.
Table 6-12. PTCDD Register Field Descriptions
Field
Description
5:0
Data Direction for Port C Bits — These read/write bits control the direction of port C pins and what is read for
PTCDD[5:0] PTCD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port C bit n and PTCD reads return the contents of PTCDn.
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6.7.6
Port C Pin Control Registers (PTCPE, PTCSE, PTCDS)
In addition to the I/O control, port C pins are controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
R
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-22. Internal Pullup Enable for Port C (PTCPE)1
1
Bit 6 is a reserved bit that must always be written to 0.
Table 6-13. PTCPE Register Field Descriptions
Field
Description
5:0
Internal Pullup Enable for Port C Bits — Each of these control bits determines if the internal pullup device is
PTCPE[5:0] enabled for the associated PTC pin. For port C pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port C bit n.
1 Internal pullup device enabled for port C bit n.
7
R
6
5
4
3
2
1
0
R
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-23. Output Slew Rate Control Enable for Port C (PTCSE)1
1
Bit 6 is a reserved bit that must always be written to 0.
Table 6-14. PTCSE Register Field Descriptions
Field
Description
5:0
Output Slew Rate Control Enable for Port C Bits — Each of these control bits determine whether output slew
PTCSE[5:0] rate control is enabled for the associated PTC pin. For port C pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port C bit n.
1 Output slew rate control enabled for port C bit n.
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7
R
6
5
4
3
2
1
0
R
PTCDS5
PTCDS4
PTCDS3
PTCDS2
PTCDS1
PTCDS0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-24. Output Drive Strength Selection for Port C (PTCDS)1
1
Bit 6 is a reserved bit that must always be written to 0.
Table 6-15. PTCDS Register Field Descriptions
Field
Description
5:0
Output Drive Strength Selection for Port C Bits — Each of these control bits selects between low and high
PTCDS[5:0] output drive for the associated PTC pin.
0 Low output drive enabled for port C bit n.
1 High output drive enabled for port C bit n.
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6.7.7
Port D I/O Registers (PTDD and PTDDD)
Port D parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
R
R
R
R
PTDD3
PTDD2
PTDD1
PTDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-25. Port D Data Register (PTDD)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-16. PTDD Register Field Descriptions
Field
Description
3:0
PTDD[3:0]
Port D Data Register Bits — For port D pins that are inputs, reads return the logic level on the pin. For port D
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port D pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTDD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
R
R
R
R
PTDDD3
PTDDD2
PTDDD1
PTDDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-26. Data Direction for Port D
1
(PTDDD)1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-17. PTDDD Register Field Descriptions
Field
Description
3:0
Data Direction for Port D Bits — These read/write bits control the direction of port D pins and what is read for
PTDDD[3:0] PTDD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port D bit n and PTDD reads return the contents of PTDDn.
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6.7.8
Port D Pin Control Registers (PTDPE, PTDSE, PTDDS)
In addition to the I/O control, port D pins are controlled by the registers listed below.
7
6
5
4
3
2
1
0
R
R
R
R
PTDPE3
PTDPE2
PTDPE1
PTDPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-27. Internal Pullup Enable for Port D (PTDPE)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-18. PTDPE Register Field Descriptions
Field
Description
3:0
Internal Pullup Enable for Port D Bits — Each of these control bits determines if the internal pullup device is
PTDPE[3:0] enabled for the associated PTD pin. For port D pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port D bit n.
1 Internal pullup device enabled for port D bit n.
7
6
5
4
3
2
1
0
R
R
R
R
PTDSE3
PTDSE2
PTDSE1
PTDSE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-28. Output Slew Rate Control Enable for Port D (PTDSE)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-19. PTDSE Register Field Descriptions
Field
Description
3:0
Output Slew Rate Control Enable for Port D Bits — Each of these control bits determine whether output slew
PTDSE[3:0] rate control is enabled for the associated PTD pin. For port D pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port D bit n.
1 Output slew rate control enabled for port D bit n.
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7
6
5
4
3
2
1
0
R
R
R
R
PTDDS3
PTDDS2
PTDDS1
PTDDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-29. Output Drive Strength Selection for Port D (PTDDS)1
1
Bits 7 through 4 are reserved bits that must always be written to 0.
Table 6-20. PTDDS Register Field Descriptions
Field
Description
3:0
Output Drive Strength Selection for Port D Bits — Each of these control bits selects between low and high
PTDDS[3:0] output drive for the associated PTD pin.
0 Low output drive enabled for port D bit n.
1 High output drive enabled for port D bit n.
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Chapter 6 Parallel Input/Output
6.7.9
Port E I/O Registers (PTED and PTEDD)
Port E parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTED7
PTED6
PTED5
PTED4
PTED3
PTED2
PTED1
PTED0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-30. Port E Data Register (PTED)
Table 6-21. PTED Register Field Descriptions
Field
Description
7:0
PTED[7:0]
Port E Data Register Bits — For port E pins that are inputs, reads return the logic level on the pin. For port E
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port E pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTED to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
PTEDD7
PTEDD6
PTEDD5
PTEDD4
PTEDD3
PTEDD2
PTEDD1
PTEDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-31. Data Direction for Port E (PTEDD)
Table 6-22. PTEDD Register Field Descriptions
Field
Description
7:0
Data Direction for Port E Bits — These read/write bits control the direction of port E pins and what is read for
PTEDD[7:0] PTED reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port E bit n and PTED reads return the contents of PTEDn.
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6.7.10
Port E Pin Control Registers (PTEPE, PTESE, PTEDS)
In addition to the I/O control, port E pins are controlled by the registers listed below.
7
6
5
4
3
2
1
0
PTEPE7
PTEPE6
PTEPE5
PTEPE4
PTEPE3
PTEPE2
PTEPE1
PTEPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-32. Internal Pullup Enable for Port E (PTEPE)
Table 6-23. PTEPE Register Field Descriptions
Field
Description
7:0
Internal Pullup Enable for Port E Bits— Each of these control bits determines if the internal pullup device is
PTEPE[7:0] enabled for the associated PTE pin. For port E pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port E bit n.
1 Internal pullup device enabled for port E bit n.
7
6
5
4
3
2
1
0
PTESE7
PTESE6
PTESE5
PTESE4
PTESE3
PTESE2
PTESE1
PTESE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-33. Output Slew Rate Control Enable for Port E (PTESE)
Table 6-24. PTESE Register Field Descriptions
Field
Description
7:0
Output Slew Rate Control Enable for Port E Bits — Each of these control bits determine whether output slew
PTESE[7:0] rate control is enabled for the associated PTE pin. For port E pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port E bit n.
1 Output slew rate control enabled for port E bit n.
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7
6
5
4
3
2
1
0
PTEDS7
PTEDS6
PTEDS5
PTEDS4
PTEDS3
PTEDS2
PTEDS1
PTEDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-34. Output Drive Strength Selection for Port E (PTEDS)
Table 6-25. PTEDS Register Field Descriptions
Field
Description
7:0
Output Drive Strength Selection for Port E Bits — Each of these control bits selects between low and high
PTEDS[7:0] output drive for the associated PTE pin.
0 Low output drive enabled for port E bit n.
1 High output drive enabled for port E bit n.
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6.7.11
Port F I/O Registers (PTFD and PTFDD)
Port F parallel I/O function is controlled by the registers listed below.
7
6
5
4
3
2
1
0
R
PTFD6
PTFD5
PTFD4
R
R
PTFD1
PTFD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-35. Port F Data Register (PTFD)1
1
Bits 7, 3 and 2 are reserved bits that must always be written to 0.
Table 6-26. PTFD Register Field Descriptions
Field
Description
6:4, 1:0
PTFDn
Port F Data Register Bits— For port F pins that are inputs, reads return the logic level on the pin. For port F
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port F pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTFD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
7
6
5
4
3
2
1
0
R
PTFDD6
PTFDD5
PTFDD4
R
R
PTFDD1
PTFDD0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-36. Data Direction for Port F
1
(PTFDD)1
Bits 7, 3 and 2 are reserved bits that must always be written to 0.
Table 6-27. PTFDD Register Field Descriptions
Field
Description
6:4, 1:0
PTFDDn
Data Direction for Port F Bits — These read/write bits control the direction of port F pins and what is read for
PTFD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port F bit n and PTFD reads return the contents of PTFDn.
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6.7.12
Port F Pin Control Registers (PTFPE, PTFSE, PTFDS)
In addition to the I/O control, port F pins are controlled by the registers listed below.
7
6
5
4
3
2
1
0
R
PTFPE6
PTFPE5
PTFPE4
R
R
PTFPE1
PTFPE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-37. Internal Pullup Enable for Port F (PTFPE)1
1
Bits 7, 3 and 2 are reserved bits that must always be written to 0.
Table 6-28. PTFPE Register Field Descriptions
Field
Description
6:4, 1:0
PTFPEn]
Internal Pullup Enable for Port F Bits — Each of these control bits determines if the internal pullup device is
enabled for the associated PTF pin. For port F pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port F bit n.
1 Internal pullup device enabled for port F bit n.
7
6
5
4
3
2
1
0
R
PTFSE6
PTFSE5
PTFSE4
R
R
PTFSE1
PTFSE0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-38. Output Slew Rate Control Enable for Port F (PTFSE)1
1
Bits 7, 3 and 2 are reserved bits that must always be written to 0.
Table 6-29. PTFSE Register Field Descriptions
Field
Description
6:4, 1:0
PTFSEn
Output Slew Rate Control Enable for Port F Bits — Each of these control bits determine whether output slew
rate control is enabled for the associated PTF pin. For port F pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port F bit n.
1 Output slew rate control enabled for port F bit n.
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7
6
5
4
3
2
1
0
R
PTFDS6
PTFDS5
PTFDS4
R
R
PTFDS1
PTFDS0
0
0
0
0
0
0
0
0
R
W
Reset
Figure 6-39. Output Drive Strength Selection for Port F (PTFDS)1
1
Bits 7, 3 and 2 are reserved bits that must always be written to 0.
Table 6-30. PTFDS Register Field Descriptions
Field
6:4, 1:0
PTFDSn
Description
Output Drive Strength Selection for Port F Bits — Each of these control bits selects between low and high
output drive for the associated PTF pin.
0 Low output drive enabled for port F bit n.
1 High output drive enabled for port F bit n.
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6.7.13
Port G I/O Registers (PTGD and PTGDD)
Port G parallel I/O function is controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
PTGD6
PTGD5
PTGD4
PTGD3
PTGD2
PTGD1
PTGD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-40. Port G Data Register (PTGD)
Table 6-31. PTGD Register Field Descriptions
Field
Description
6:0
PTGD[6:0]
Port G Data Register Bits — For port G pins that are inputs, reads return the logic level on the pin. For port G
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port G pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTGD to all 0s, but these 0s are not driven out the corresponding pins because reset also
configures all port pins as high-impedance inputs with pullups disabled.
7
R
6
5
4
3
2
1
0
PTGDD6
PTGDD5
PTGDD4
PTGDD3
PTGDD2
PTGDD1
PTGDD0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-41. Data Direction for Port G (PTGDD)
Table 6-32. PTGDD Register Field Descriptions
Field
Description
6:0
Data Direction for Port G Bits — These read/write bits control the direction of port G pins and what is read for
PTGDD[6:0] PTGD reads.
0 Input (output driver disabled) and reads return the pin value.
1 Output driver enabled for port G bit n and PTGD reads return the contents of PTGDn.
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6.7.14
Port G Pin Control Registers (PTGPE, PTGSE, PTGDS)
In addition to the I/O control, port G pins are controlled by the registers listed below.
7
R
6
5
4
3
2
1
0
PTGPE6
PTGPE5
PTGPE4
PTGPE3
PTGPE2
PTGPE1
PTGPE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-42. Internal Pullup Enable for Port G Bits (PTGPE)
Table 6-33. PTGPE Register Field Descriptions
Field
Description
6:0
Internal Pullup Enable for Port G Bits — Each of these control bits determines if the internal pullup device is
PTGPE[6:0] enabled for the associated PTG pin. For port G pins that are configured as outputs, these bits have no effect and
the internal pullup devices are disabled.
0 Internal pullup device disabled for port G bit n.
1 Internal pullup device enabled for port G bit n.
7
R
6
5
4
3
2
1
0
PTGSE6
PTGSE5
PTGSE4
PTGSE3
PTGSE2
PTGSE1
PTGSE0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-43. Output Slew Rate Control Enable for Port G Bits (PTGSE)
Table 6-34. PTGSE Register Field Descriptions
Field
Description
6:0
Output Slew Rate Control Enable for Port G Bits— Each of these control bits determine whether output slew
PTGSE[6:0] rate control is enabled for the associated PTG pin. For port G pins that are configured as inputs, these bits have
no effect.
0 Output slew rate control disabled for port G bit n.
1 Output slew rate control enabled for port G bit n.
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R
6
5
4
3
2
1
0
PTGDS6
PTGDS5
PTGDS4
PTGDS3
PTGDS2
PTGDS1
PTGDS0
0
0
0
0
0
0
0
0
W
Reset
0
Figure 6-44. Output Drive Strength Selection for Port G (PTGDS)
Table 6-35. PTGDS Register Field Descriptions
Field
Description
6:0
Output Drive Strength Selection for Port G Bits — Each of these control bits selects between low and high
PTGDS[6:0] output drive for the associated PTG pin.
0 Low output drive enabled for port G bit n.
1 High output drive enabled for port G bit n.
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Chapter 7
Central Processor Unit (S08CPUV2)
7.1
Introduction
This section provides summary information about the registers, addressing modes, and instruction set of
the CPU of the HCS08 Family. For a more detailed discussion, refer to the HCS08 Family Reference
Manual, volume 1, Freescale Semiconductor document order number HCS08RMV1/D.
The HCS08 CPU is fully source- and object-code-compatible with the M68HC08 CPU. Several
instructions and enhanced addressing modes were added to improve C compiler efficiency and to support
a new background debug system which replaces the monitor mode of earlier M68HC08 microcontrollers
(MCU).
7.1.1
Features
Features of the HCS08 CPU include:
• Object code fully upward-compatible with M68HC05 and M68HC08 Families
• All registers and memory are mapped to a single 64-Kbyte address space
• 16-bit stack pointer (any size stack anywhere in 64-Kbyte address space)
• 16-bit index register (H:X) with powerful indexed addressing modes
• 8-bit accumulator (A)
• Many instructions treat X as a second general-purpose 8-bit register
• Seven addressing modes:
— Inherent — Operands in internal registers
— Relative — 8-bit signed offset to branch destination
— Immediate — Operand in next object code byte(s)
— Direct — Operand in memory at 0x0000–0x00FF
— Extended — Operand anywhere in 64-Kbyte address space
— Indexed relative to H:X — Five submodes including auto increment
— Indexed relative to SP — Improves C efficiency dramatically
• Memory-to-memory data move instructions with four address mode combinations
• Overflow, half-carry, negative, zero, and carry condition codes support conditional branching on
the results of signed, unsigned, and binary-coded decimal (BCD) operations
• Efficient bit manipulation instructions
• Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
• STOP and WAIT instructions to invoke low-power operating modes
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7.2
Programmer’s Model and CPU Registers
Figure 7-1 shows the five CPU registers. CPU registers are not part of the memory map.
7
0
ACCUMULATOR
A
16-BIT INDEX REGISTER H:X
H INDEX REGISTER (HIGH)
8
15
INDEX REGISTER (LOW)
X
0
7
SP
STACK POINTER
0
15
PROGRAM COUNTER
7
0
CONDITION CODE REGISTER V 1 1 H I N Z C
PC
CCR
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
Figure 7-1. CPU Registers
7.2.1
Accumulator (A)
The A accumulator is a general-purpose 8-bit register. One operand input to the arithmetic logic unit
(ALU) is connected to the accumulator and the ALU results are often stored into the A accumulator after
arithmetic and logical operations. The accumulator can be loaded from memory using various addressing
modes to specify the address where the loaded data comes from, or the contents of A can be stored to
memory using various addressing modes to specify the address where data from A will be stored.
Reset has no effect on the contents of the A accumulator.
7.2.2
Index Register (H:X)
This 16-bit register is actually two separate 8-bit registers (H and X), which often work together as a 16-bit
address pointer where H holds the upper byte of an address and X holds the lower byte of the address. All
indexed addressing mode instructions use the full 16-bit value in H:X as an index reference pointer;
however, for compatibility with the earlier M68HC05 Family, some instructions operate only on the
low-order 8-bit half (X).
Many instructions treat X as a second general-purpose 8-bit register that can be used to hold 8-bit data
values. X can be cleared, incremented, decremented, complemented, negated, shifted, or rotated. Transfer
instructions allow data to be transferred from A or transferred to A where arithmetic and logical operations
can then be performed.
For compatibility with the earlier M68HC05 Family, H is forced to 0x00 during reset. Reset has no effect
on the contents of X.
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7.2.3
Stack Pointer (SP)
This 16-bit address pointer register points at the next available location on the automatic last-in-first-out
(LIFO) stack. The stack may be located anywhere in the 64-Kbyte address space that has RAM and can
be any size up to the amount of available RAM. The stack is used to automatically save the return address
for subroutine calls, the return address and CPU registers during interrupts, and for local variables. The
AIS (add immediate to stack pointer) instruction adds an 8-bit signed immediate value to SP. This is most
often used to allocate or deallocate space for local variables on the stack.
SP is forced to 0x00FF at reset for compatibility with the earlier M68HC05 Family. HCS08 programs
normally change the value in SP to the address of the last location (highest address) in on-chip RAM
during reset initialization to free up direct page RAM (from the end of the on-chip registers to 0x00FF).
The RSP (reset stack pointer) instruction was included for compatibility with the M68HC05 Family and
is seldom used in new HCS08 programs because it only affects the low-order half of the stack pointer.
7.2.4
Program Counter (PC)
The program counter is a 16-bit register that contains the address of the next instruction or operand to be
fetched.
During normal program execution, the program counter automatically increments to the next sequential
memory location every time an instruction or operand is fetched. Jump, branch, interrupt, and return
operations load the program counter with an address other than that of the next sequential location. This
is called a change-of-flow.
During reset, the program counter is loaded with the reset vector that is located at 0xFFFE and 0xFFFF.
The vector stored there is the address of the first instruction that will be executed after exiting the reset
state.
7.2.5
Condition Code Register (CCR)
The 8-bit condition code register contains the interrupt mask (I) and five flags that indicate the results of
the instruction just executed. Bits 6 and 5 are set permanently to 1. The following paragraphs describe the
functions of the condition code bits in general terms. For a more detailed explanation of how each
instruction sets the CCR bits, refer to the HCS08 Family Reference Manual, volume 1, Freescale
Semiconductor document order number HCS08RMv1.
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7
0
CONDITION CODE REGISTER V 1 1 H I N Z C
CCR
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
Figure 7-2. Condition Code Register
Table 7-1. CCR Register Field Descriptions
Field
Description
7
V
Two’s Complement Overflow Flag — The CPU sets the overflow flag when a two’s complement overflow occurs.
The signed branch instructions BGT, BGE, BLE, and BLT use the overflow flag.
0 No overflow
1 Overflow
4
H
Half-Carry Flag — The CPU sets the half-carry flag when a carry occurs between accumulator bits 3 and 4 during
an add-without-carry (ADD) or add-with-carry (ADC) operation. The half-carry flag is required for binary-coded
decimal (BCD) arithmetic operations. The DAA instruction uses the states of the H and C condition code bits to
automatically add a correction value to the result from a previous ADD or ADC on BCD operands to correct the
result to a valid BCD value.
0 No carry between bits 3 and 4
1 Carry between bits 3 and 4
3
I
Interrupt Mask Bit — When the interrupt mask is set, all maskable CPU interrupts are disabled. CPU interrupts
are enabled when the interrupt mask is cleared. When a CPU interrupt occurs, the interrupt mask is set
automatically after the CPU registers are saved on the stack, but before the first instruction of the interrupt service
routine is executed.
Interrupts are not recognized at the instruction boundary after any instruction that clears I (CLI or TAP). This
ensures that the next instruction after a CLI or TAP will always be executed without the possibility of an intervening
interrupt, provided I was set.
0 Interrupts enabled
1 Interrupts disabled
2
N
Negative Flag — The CPU sets the negative flag when an arithmetic operation, logic operation, or data
manipulation produces a negative result, setting bit 7 of the result. Simply loading or storing an 8-bit or 16-bit value
causes N to be set if the most significant bit of the loaded or stored value was 1.
0 Non-negative result
1 Negative result
1
Z
Zero Flag — The CPU sets the zero flag when an arithmetic operation, logic operation, or data manipulation
produces a result of 0x00 or 0x0000. Simply loading or storing an 8-bit or 16-bit value causes Z to be set if the
loaded or stored value was all 0s.
0 Non-zero result
1 Zero result
0
C
Carry/Borrow Flag — The CPU sets the carry/borrow flag when an addition operation produces a carry out of bit
7 of the accumulator or when a subtraction operation requires a borrow. Some instructions — such as bit test and
branch, shift, and rotate — also clear or set the carry/borrow flag.
0 No carry out of bit 7
1 Carry out of bit 7
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7.3
Addressing Modes
Addressing modes define the way the CPU accesses operands and data. In the HCS08, all memory, status
and control registers, and input/output (I/O) ports share a single 64-Kbyte linear address space so a 16-bit
binary address can uniquely identify any memory location. This arrangement means that the same
instructions that access variables in RAM can also be used to access I/O and control registers or nonvolatile
program space.
Some instructions use more than one addressing mode. For instance, move instructions use one addressing
mode to specify the source operand and a second addressing mode to specify the destination address.
Instructions such as BRCLR, BRSET, CBEQ, and DBNZ use one addressing mode to specify the location
of an operand for a test and then use relative addressing mode to specify the branch destination address
when the tested condition is true. For BRCLR, BRSET, CBEQ, and DBNZ, the addressing mode listed in
the instruction set tables is the addressing mode needed to access the operand to be tested, and relative
addressing mode is implied for the branch destination.
7.3.1
Inherent Addressing Mode (INH)
In this addressing mode, operands needed to complete the instruction (if any) are located within CPU
registers so the CPU does not need to access memory to get any operands.
7.3.2
Relative Addressing Mode (REL)
Relative addressing mode is used to specify the destination location for branch instructions. A signed 8-bit
offset value is located in the memory location immediately following the opcode. During execution, if the
branch condition is true, the signed offset is sign-extended to a 16-bit value and is added to the current
contents of the program counter, which causes program execution to continue at the branch destination
address.
7.3.3
Immediate Addressing Mode (IMM)
In immediate addressing mode, the operand needed to complete the instruction is included in the object
code immediately following the instruction opcode in memory. In the case of a 16-bit immediate operand,
the high-order byte is located in the next memory location after the opcode, and the low-order byte is
located in the next memory location after that.
7.3.4
Direct Addressing Mode (DIR)
In direct addressing mode, the instruction includes the low-order eight bits of an address in the direct page
(0x0000–0x00FF). During execution a 16-bit address is formed by concatenating an implied 0x00 for the
high-order half of the address and the direct address from the instruction to get the 16-bit address where
the desired operand is located. This is faster and more memory efficient than specifying a complete 16-bit
address for the operand.
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7.3.5
Extended Addressing Mode (EXT)
In extended addressing mode, the full 16-bit address of the operand is located in the next two bytes of
program memory after the opcode (high byte first).
7.3.6
Indexed Addressing Mode
Indexed addressing mode has seven variations including five that use the 16-bit H:X index register pair and
two that use the stack pointer as the base reference.
7.3.6.1
Indexed, No Offset (IX)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair as the address of
the operand needed to complete the instruction.
7.3.6.2
Indexed, No Offset with Post Increment (IX+)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair as the address of
the operand needed to complete the instruction. The index register pair is then incremented
(H:X = H:X + 0x0001) after the operand has been fetched. This addressing mode is only used for MOV
and CBEQ instructions.
7.3.6.3
Indexed, 8-Bit Offset (IX1)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus an unsigned
8-bit offset included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.4
Indexed, 8-Bit Offset with Post Increment (IX1+)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus an unsigned
8-bit offset included in the instruction as the address of the operand needed to complete the instruction.
The index register pair is then incremented (H:X = H:X + 0x0001) after the operand has been fetched. This
addressing mode is used only for the CBEQ instruction.
7.3.6.5
Indexed, 16-Bit Offset (IX2)
This variation of indexed addressing uses the 16-bit value in the H:X index register pair plus a 16-bit offset
included in the instruction as the address of the operand needed to complete the instruction.
7.3.6.6
SP-Relative, 8-Bit Offset (SP1)
This variation of indexed addressing uses the 16-bit value in the stack pointer (SP) plus an unsigned 8-bit
offset included in the instruction as the address of the operand needed to complete the instruction.
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7.3.6.7
SP-Relative, 16-Bit Offset (SP2)
This variation of indexed addressing uses the 16-bit value in the stack pointer (SP) plus a 16-bit offset
included in the instruction as the address of the operand needed to complete the instruction.
7.4
Special Operations
The CPU performs a few special operations that are similar to instructions but do not have opcodes like
other CPU instructions. In addition, a few instructions such as STOP and WAIT directly affect other MCU
circuitry. This section provides additional information about these operations.
7.4.1
Reset Sequence
Reset can be caused by a power-on-reset (POR) event, internal conditions such as the COP (computer
operating properly) watchdog, or by assertion of an external active-low reset pin. When a reset event
occurs, the CPU immediately stops whatever it is doing (the MCU does not wait for an instruction
boundary before responding to a reset event). For a more detailed discussion about how the MCU
recognizes resets and determines the source, refer to the Resets, Interrupts, and System Configuration
chapter.
The reset event is considered concluded when the sequence to determine whether the reset came from an
internal source is done and when the reset pin is no longer asserted. At the conclusion of a reset event, the
CPU performs a 6-cycle sequence to fetch the reset vector from 0xFFFE and 0xFFFF and to fill the
instruction queue in preparation for execution of the first program instruction.
7.4.2
Interrupt Sequence
When an interrupt is requested, the CPU completes the current instruction before responding to the
interrupt. At this point, the program counter is pointing at the start of the next instruction, which is where
the CPU should return after servicing the interrupt. The CPU responds to an interrupt by performing the
same sequence of operations as for a software interrupt (SWI) instruction, except the address used for the
vector fetch is determined by the highest priority interrupt that is pending when the interrupt sequence
started.
The CPU sequence for an interrupt is:
1. Store the contents of PCL, PCH, X, A, and CCR on the stack, in that order.
2. Set the I bit in the CCR.
3. Fetch the high-order half of the interrupt vector.
4. Fetch the low-order half of the interrupt vector.
5. Delay for one free bus cycle.
6. Fetch three bytes of program information starting at the address indicated by the interrupt vector
to fill the instruction queue in preparation for execution of the first instruction in the interrupt
service routine.
After the CCR contents are pushed onto the stack, the I bit in the CCR is set to prevent other interrupts
while in the interrupt service routine. Although it is possible to clear the I bit with an instruction in the
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interrupt service routine, this would allow nesting of interrupts (which is not recommended because it
leads to programs that are difficult to debug and maintain).
For compatibility with the earlier M68HC05 MCUs, the high-order half of the H:X index register pair (H)
is not saved on the stack as part of the interrupt sequence. The user must use a PSHH instruction at the
beginning of the service routine to save H and then use a PULH instruction just before the RTI that ends
the interrupt service routine. It is not necessary to save H if you are certain that the interrupt service routine
does not use any instructions or auto-increment addressing modes that might change the value of H.
The software interrupt (SWI) instruction is like a hardware interrupt except that it is not masked by the
global I bit in the CCR and it is associated with an instruction opcode within the program so it is not
asynchronous to program execution.
7.4.3
Wait Mode Operation
The WAIT instruction enables interrupts by clearing the I bit in the CCR. It then halts the clocks to the
CPU to reduce overall power consumption while the CPU is waiting for the interrupt or reset event that
will wake the CPU from wait mode. When an interrupt or reset event occurs, the CPU clocks will resume
and the interrupt or reset event will be processed normally.
If a serial BACKGROUND command is issued to the MCU through the background debug interface while
the CPU is in wait mode, CPU clocks will resume and the CPU will enter active background mode where
other serial background commands can be processed. This ensures that a host development system can still
gain access to a target MCU even if it is in wait mode.
7.4.4
Stop Mode Operation
Usually, all system clocks, including the crystal oscillator (when used), are halted during stop mode to
minimize power consumption. In such systems, external circuitry is needed to control the time spent in
stop mode and to issue a signal to wake up the target MCU when it is time to resume processing. Unlike
the earlier M68HC05 and M68HC08 MCUs, the HCS08 can be configured to keep a minimum set of
clocks running in stop mode. This optionally allows an internal periodic signal to wake the target MCU
from stop mode.
When a host debug system is connected to the background debug pin (BKGD) and the ENBDM control
bit has been set by a serial command through the background interface (or because the MCU was reset into
active background mode), the oscillator is forced to remain active when the MCU enters stop mode. In this
case, if a serial BACKGROUND command is issued to the MCU through the background debug interface
while the CPU is in stop mode, CPU clocks will resume and the CPU will enter active background mode
where other serial background commands can be processed. This ensures that a host development system
can still gain access to a target MCU even if it is in stop mode.
Recovery from stop mode depends on the particular HCS08 and whether the oscillator was stopped in stop
mode. Refer to the Modes of Operation chapter for more details.
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7.4.5
BGND Instruction
The BGND instruction is new to the HCS08 compared to the M68HC08. BGND would not be used in
normal user programs because it forces the CPU to stop processing user instructions and enter the active
background mode. The only way to resume execution of the user program is through reset or by a host
debug system issuing a GO, TRACE1, or TAGGO serial command through the background debug
interface.
Software-based breakpoints can be set by replacing an opcode at the desired breakpoint address with the
BGND opcode. When the program reaches this breakpoint address, the CPU is forced to active background
mode rather than continuing the user program.
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7.5
HCS08 Instruction Set Summary
Instruction Set Summary Nomenclature
The nomenclature listed here is used in the instruction descriptions in Table 7-2.
Operators
()
←
&
|
⊕
×
÷
:
+
–
=
=
=
=
=
=
=
=
=
=
CPU registers
A =
CCR =
H =
X =
PC =
PCH =
PCL =
SP =
Contents of register or memory location shown inside parentheses
Is loaded with (read: “gets”)
Boolean AND
Boolean OR
Boolean exclusive-OR
Multiply
Divide
Concatenate
Add
Negate (two’s complement)
Accumulator
Condition code register
Index register, higher order (most significant) 8 bits
Index register, lower order (least significant) 8 bits
Program counter
Program counter, higher order (most significant) 8 bits
Program counter, lower order (least significant) 8 bits
Stack pointer
Memory and addressing
M = A memory location or absolute data, depending on addressing mode
M:M + 0x0001= A 16-bit value in two consecutive memory locations. The higher-order (most
significant) 8 bits are located at the address of M, and the lower-order (least
significant) 8 bits are located at the next higher sequential address.
Condition code register (CCR) bits
V = Two’s complement overflow indicator, bit 7
H = Half carry, bit 4
I = Interrupt mask, bit 3
N = Negative indicator, bit 2
Z = Zero indicator, bit 1
C = Carry/borrow, bit 0 (carry out of bit 7)
CCR activity notation
– = Bit not affected
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0
1
U
=
=
=
=
Bit forced to 0
Bit forced to 1
Bit set or cleared according to results of operation
Undefined after the operation
Machine coding notation
dd = Low-order 8 bits of a direct address 0x0000–0x00FF (high byte assumed to be 0x00)
ee = Upper 8 bits of 16-bit offset
ff = Lower 8 bits of 16-bit offset or 8-bit offset
ii = One byte of immediate data
jj = High-order byte of a 16-bit immediate data value
kk = Low-order byte of a 16-bit immediate data value
hh = High-order byte of 16-bit extended address
ll = Low-order byte of 16-bit extended address
rr = Relative offset
Source form
Everything in the source forms columns, except expressions in italic characters, is literal information that
must appear in the assembly source file exactly as shown. The initial 3- to 5-letter mnemonic is always a
literal expression. All commas, pound signs (#), parentheses, and plus signs (+) are literal characters.
n — Any label or expression that evaluates to a single integer in the range 0–7
opr8i — Any label or expression that evaluates to an 8-bit immediate value
opr16i — Any label or expression that evaluates to a 16-bit immediate value
opr8a — Any label or expression that evaluates to an 8-bit value. The instruction treats this 8-bit
value as the low order 8 bits of an address in the direct page of the 64-Kbyte address
space (0x00xx).
opr16a — Any label or expression that evaluates to a 16-bit value. The instruction treats this
value as an address in the 64-Kbyte address space.
oprx8 — Any label or expression that evaluates to an unsigned 8-bit value, used for indexed
addressing
oprx16 — Any label or expression that evaluates to a 16-bit value. Because the HCS08 has a
16-bit address bus, this can be either a signed or an unsigned value.
rel — Any label or expression that refers to an address that is within –128 to +127 locations
from the next address after the last byte of object code for the current instruction. The
assembler will calculate the 8-bit signed offset and include it in the object code for this
instruction.
Address modes
INH =
IMM =
DIR =
EXT =
Inherent (no operands)
8-bit or 16-bit immediate
8-bit direct
16-bit extended
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IX
IX+
IX1
IX1+
=
=
=
=
IX2
REL
SP1
SP2
=
=
=
=
16-bit indexed no offset
16-bit indexed no offset, post increment (CBEQ and MOV only)
16-bit indexed with 8-bit offset from H:X
16-bit indexed with 8-bit offset, post increment
(CBEQ only)
16-bit indexed with 16-bit offset from H:X
8-bit relative offset
Stack pointer with 8-bit offset
Stack pointer with 16-bit offset
Description
V H I N Z C
ADC
ADC
ADC
ADC
ADC
ADC
ADC
ADC
ADD
ADD
ADD
ADD
ADD
ADD
ADD
ADD
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
AIS #opr8i
AIX #opr8i
AND #opr8i
AND opr8a
AND opr16a
AND oprx16,X
AND oprx8,X
AND ,X
AND oprx16,SP
AND oprx8,SP
ASL opr8a
ASLA
ASLX
ASL oprx8,X
ASL ,X
ASL oprx8,SP
ASR opr8a
ASRA
ASRX
ASR oprx8,X
ASR ,X
ASR oprx8,SP
BCC rel
A ← (A) + (M) + (C)
Add with Carry
A ← (A) + (M)
Add without Carry
Add Immediate Value
(Signed) to Stack Pointer
Add Immediate Value
(Signed) to Index
Register (H:X)
↕ – ↕
↕
↕
ii
dd
hh ll
ee ff
ff
ee ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
2
3
4
4
3
3
5
4
– – – – – – IMM
A7 ii
2
H:X ← (H:X) + (M)
M is sign extended to a 16-bit value
– – – – – – IMM
AF ii
2
A ← (A) & (M)
C
0 – – ↕
0
b7
C
b7
↕ – – ↕
↕ –
↕
↕
b0
Arithmetic Shift Right
Branch if Carry Bit Clear
↕
↕ – ↕
A9
B9
C9
D9
E9
F9
9ED9
9EE9
AB
BB
CB
DB
EB
FB
9EDB
9EEB
SP ← (SP) + (M)
M is sign extended to a 16-bit value
Logical AND
Arithmetic Shift Left
(Same as LSL)
↕
IMM
DIR
EXT
↕ IX2
IX1
IX
SP2
SP1
IMM
DIR
EXT
↕ IX2
IX1
IX
SP2
SP1
Bus Cycles1
Operation
Operand
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 1 of 7)
b0
Branch if (C) = 0
↕ – – ↕
↕
↕
– – – – – –
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
DIR
INH
INH
IX1
IX
SP1
DIR
INH
INH
IX1
IX
SP1
REL
A4
B4
C4
D4
E4
F4
9ED4
9EE4
38
48
58
68
78
9E68
37
47
57
67
77
9E67
24
ii
dd
hh ll
ee ff
ff
ee ff
ff
dd
ff
ff
dd
ff
ff
rr
2
3
4
4
3
3
5
4
5
1
1
5
4
6
5
1
1
5
4
6
3
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V H I N Z C
DIR (b0)
DIR (b1)
DIR (b2)
(b3)
– – – – – – DIR
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 2 of 7)
5
5
5
5
5
5
5
5
BCLR n,opr8a
Clear Bit n in Memory
Mn ← 0
BCS rel
Branch if Carry Bit Set
(Same as BLO)
Branch if (C) = 1
– – – – – – REL
25 rr
3
BEQ rel
Branch if Equal
Branch if (Z) = 1
– – – – – – REL
27 rr
3
BGE rel
Branch if Greater Than or
Equal To
(Signed Operands)
Branch if (N ⊕ V) = 0
– – – – – – REL
90 rr
3
BGND
Enter Active Background
if ENBDM = 1
Waits For and Processes BDM
Commands Until GO, TRACE1, or
TAGGO
– – – – – – INH
82
5+
BGT rel
Branch if Greater Than
(Signed Operands)
Branch if Half Carry Bit
Clear
Branch if Half Carry Bit
Set
Branch if (Z) | (N ⊕ V) = 0
– – – – – – REL
92 rr
3
Branch if (H) = 0
– – – – – – REL
28 rr
3
Branch if (H) = 1
– – – – – – REL
29 rr
3
Branch if (C) | (Z) = 0
– – – – – – REL
22 rr
3
Branch if (C) = 0
– – – – – – REL
24 rr
3
– – – – – – REL
– – – – – – REL
2F rr
3
2E rr
BHCC rel
BHCS rel
BHI rel
Branch if Higher
BHS rel
Branch if Higher or Same
(Same as BCC)
BIH rel
Branch if IRQ Pin High
Branch if IRQ pin = 1
BIL rel
Branch if IRQ Pin Low
Branch if IRQ pin = 0
BIT
BIT
BIT
BIT
BIT
BIT
BIT
BIT
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
(A) & (M)
(CCR Updated but Operands
Not Changed)
Bit Test
0 – – ↕
IMM
DIR
EXT
↕ – IX2
IX1
IX
SP2
SP1
A5
B5
C5
D5
E5
F5
9ED5
9EE5
ii
dd
hh ll
ee ff
ff
ee ff
ff
3
2
3
4
4
3
3
5
4
BLO rel
Branch if Less Than
or Equal To
(Signed Operands)
Branch if Lower
(Same as BCS)
BLS rel
Branch if Lower or Same
Branch if (C) | (Z) = 1
– – – – – – REL
23 rr
3
BLT rel
Branch if (N ⊕ V ) = 1
– – – – – – REL
91 rr
3
BMC rel
Branch if Less Than
(Signed Operands)
Branch if Interrupt Mask
Clear
Branch if (I) = 0
– – – – – – REL
2C rr
3
BMI rel
Branch if Minus
Branch if (N) = 1
– – – – – – REL
2B rr
3
BMS rel
Branch if Interrupt Mask
Set
Branch if (I) = 1
– – – – – – REL
2D rr
3
BNE rel
Branch if Not Equal
Branch if (Z) = 0
3
Branch if Plus
Branch if (N) = 0
2A rr
3
BRA rel
Branch Always
No Test
– – – – – – REL
– – – – – – REL
– – – – – – REL
26 rr
BPL rel
20 rr
3
BLE rel
Branch if (Z) | (N ⊕ V) = 1
– – – – – – REL
93 rr
3
Branch if (C) = 1
– – – – – – REL
25 rr
3
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V H I N Z C
BRCLR n,opr8a,rel
Branch if Bit n in Memory
Clear
Branch if (Mn) = 0
DIR (b0)
DIR (b1)
DIR (b2)
(b3)
– – – – – ↕ DIR
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
BRN rel
Branch Never
Uses 3 Bus Cycles
– – – – – – REL
21 rr
Branch if (Mn) = 1
DIR (b0)
DIR (b1)
DIR (b2)
(b3)
– – – – – ↕ DIR
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
dd
dd
dd
dd
dd
dd
dd
dd
Mn ← 1
DIR (b0)
DIR (b1)
DIR (b2)
(b3)
– – – – – – DIR
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
– – – – – – REL
AD rr
BRSET n,opr8a,rel
Branch if Bit n in Memory
Set
BSET n,opr8a
Set Bit n in Memory
BSR rel
Branch to Subroutine
PC ← (PC) + 0x0002
push (PCL); SP ← (SP) – 0x0001
push (PCH); SP ← (SP) – 0x0001
PC ← (PC) + rel
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (X) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
Compare and Branch if
Equal
CLC
Clear Carry Bit
C←0
CLI
Clear Interrupt Mask Bit
CLR opr8a
CLRA
CLRX
CLRH
CLR oprx8,X
CLR ,X
CLR oprx8,SP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
COM opr8a
COMA
COMX
COM oprx8,X
COM ,X
COM oprx8,SP
CPHX opr16a
CPHX #opr16i
CPHX opr8a
CPHX oprx8,SP
Clear
Compare Accumulator
with Memory
Complement
(One’s Complement)
Compare Index Register
(H:X) with Memory
DIR
IMM
– – – – – – IMM
IX1+
IX+
SP1
01
03
05
07
09
0B
0D
0F
31
41
51
61
71
9E61
dd
dd
dd
dd
dd
dd
dd
dd
dd
ii
ii
ff
rr
ff
rr
rr
rr
rr
rr
rr
rr
rr
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 3 of 7)
5
5
5
5
5
5
5
5
3
rr
rr
rr
rr
rr
rr
rr
rr
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
rr
rr
rr
rr
rr
5
4
4
5
5
6
98
1
I←0
– – – – – 0 INH
– – 0 – – – INH
9A
1
M ← 0x00
A ← 0x00
X ← 0x00
H ← 0x00
M ← 0x00
M ← 0x00
M ← 0x00
DIR
INH
INH
0 – – 0 1 – INH
IX1
IX
SP1
3F dd
4F
5F
8C
6F ff
7F
9E6F ff
5
1
1
1
5
4
6
A1
B1
C1
D1
E1
F1
9ED1
9EE1
33
43
53
63
73
9E63
3E
65
75
9EF3
2
3
4
4
3
3
5
4
5
1
1
5
4
6
6
3
5
6
(A) – (M)
(CCR Updated But Operands Not
Changed)
↕ – – ↕
M ← (M)= 0xFF – (M)
A ← (A) = 0xFF – (A)
X ← (X) = 0xFF – (X)
M ← (M) = 0xFF – (M)
M ← (M) = 0xFF – (M)
M ← (M) = 0xFF – (M)
0 – – ↕
(H:X) – (M:M + 0x0001)
(CCR Updated But Operands Not
Changed)
↕ – – ↕
IMM
DIR
EXT
IX2
↕ ↕ IX1
IX
SP2
SP1
DIR
INH
↕ 1 INH
IX1
IX
SP1
EXT
↕ ↕ IMM
DIR
SP1
ii
dd
hh ll
ee ff
ff
ee ff
ff
dd
ff
ff
hh ll
jj kk
dd
ff
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V H I N Z C
CPX
CPX
CPX
CPX
CPX
CPX
CPX
CPX
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
DAA
DBNZ opr8a,rel
DBNZA rel
DBNZX rel
DBNZ oprx8,X,rel
DBNZ ,X,rel
DBNZ oprx8,SP,rel
DEC opr8a
DECA
DECX
DEC oprx8,X
DEC ,X
DEC oprx8,SP
DIV
EOR #opr8i
EOR opr8a
EOR opr16a
EOR oprx16,X
EOR oprx8,X
EOR ,X
EOR oprx16,SP
EOR oprx8,SP
INC opr8a
INCA
INCX
INC oprx8,X
INC ,X
INC oprx8,SP
JMP opr8a
JMP opr16a
JMP oprx16,X
JMP oprx8,X
JMP ,X
JSR opr8a
JSR opr16a
JSR oprx16,X
JSR oprx8,X
JSR ,X
LDA #opr8i
LDA opr8a
LDA opr16a
LDA oprx16,X
LDA oprx8,X
LDA ,X
LDA oprx16,SP
LDA oprx8,SP
LDHX #opr16i
LDHX opr8a
LDHX opr16a
LDHX ,X
LDHX oprx16,X
LDHX oprx8,X
LDHX oprx8,SP
Compare X (Index
Register Low) with
Memory
(X) – (M)
(CCR Updated But Operands Not
Changed)
↕ – – ↕
↕
IMM
DIR
EXT
↕ IX2
IX1
IX
SP2
SP1
A3
B3
C3
D3
E3
F3
9ED3
9EE3
Decimal Adjust
Accumulator After ADD or
ADC of BCD Values
(A)10
U – – ↕ ↕ ↕ INH
72
Decrement and Branch if
Not Zero
Decrement A, X, or M
Branch if (result) ≠ 0
DBNZX Affects X Not H
DIR
INH
– – – – – – INH
IX1
IX
SP1
3B
4B
5B
6B
7B
9E6B
Decrement
M ← (M) – 0x01
A ← (A) – 0x01
X ← (X) – 0x01
M ← (M) – 0x01
M ← (M) – 0x01
M ← (M) – 0x01
↕ – – ↕
Divide
A ← (H:A)÷(X)
H ← Remainder
Exclusive OR
Memory with
Accumulator
A ← (A ⊕ M)
M ← (M) + 0x01
A ← (A) + 0x01
X ← (X) + 0x01
M ← (M) + 0x01
M ← (M) + 0x01
M ← (M) + 0x01
Increment
PC ← Jump Address
Jump
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – 0x0001
Push (PCH); SP ← (SP) – 0x0001
PC ← Unconditional Address
Jump to Subroutine
Load Accumulator from
Memory
A ← (M)
Load Index Register (H:X)
from Memory
H:X ← (M:M + 0x0001)
DIR
INH
↕ – INH
IX1
IX
SP1
ii
dd
hh ll
ee ff
ff
ee ff
ff
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 4 of 7)
2
3
4
4
3
3
5
4
1
dd rr
rr
rr
ff rr
rr
ff rr
7
4
4
7
6
8
3A dd
4A
5A
6A ff
7A
9E6A ff
5
1
1
5
4
6
– – – – ↕ ↕ INH
52
6
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
DIR
INH
INH
IX1
IX
SP1
DIR
EXT
IX2
IX1
IX
DIR
EXT
IX2
IX1
IX
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
IMM
DIR
EXT
IX
IX2
IX1
SP1
A8
B8
C8
D8
E8
F8
9ED8
9EE8
3C
4C
5C
6C
7C
9E6C
BC
CC
DC
EC
FC
BD
CD
DD
ED
FD
A6
B6
C6
D6
E6
F6
9ED6
9EE6
45
55
32
9EAE
9EBE
9ECE
9EFE
0 – – ↕ ↕ –
↕ – – ↕
↕ –
– – – – – –
– – – – – –
0 – – ↕ ↕ –
0 – – ↕ ↕ –
ii
dd
hh ll
ee ff
ff
ee ff
ff
dd
ff
ff
dd
hh ll
ee ff
ff
dd
hh ll
ee ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
jj kk
dd
hh ll
ee ff
ff
ff
2
3
4
4
3
3
5
4
5
1
1
5
4
6
3
4
4
3
3
5
6
6
5
5
2
3
4
4
3
3
5
4
3
4
5
5
6
5
5
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
125
Chapter 7 Central Processor Unit (S08CPUV2)
V H I N Z C
LDX #opr8i
LDX opr8a
LDX opr16a
LDX oprx16,X
LDX oprx8,X
LDX ,X
LDX oprx16,SP
LDX oprx8,SP
LSL opr8a
LSLA
LSLX
LSL oprx8,X
LSL ,X
LSL oprx8,SP
LSR opr8a
LSRA
LSRX
LSR oprx8,X
LSR ,X
LSR oprx8,SP
Load X (Index Register
Low) from Memory
X ← (M)
Logical Shift Left
(Same as ASL)
0 – – ↕
C
0
b7
0
Logical Shift Right
C
b7
b0
(M)destination ← (M)source
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
Move
MUL
Unsigned multiply
↕ – – ↕
b0
H:X ← (H:X) + 0x0001 in
IX+/DIR and DIR/IX+ Modes
X:A ← (X) × (A)
M ← – (M) = 0x00 – (M)
A ← – (A) = 0x00 – (A)
X ← – (X) = 0x00 – (X)
M ← – (M) = 0x00 – (M)
M ← – (M) = 0x00 – (M)
M ← – (M) = 0x00 – (M)
IMM
DIR
EXT
↕ – IX2
IX1
IX
SP2
SP1
DIR
INH
↕ ↕ INH
IX1
IX
SP1
DIR
INH
↕ – – 0 ↕ ↕ INH
IX1
IX
SP1
DIR/DIR
0 – – ↕ ↕ – DIR/IX+
IMM/DIR
IX+/DIR
– 0 – – – 0 INH
AE
BE
CE
DE
EE
FE
9EDE
9EEE
38
48
58
68
78
9E68
ii
dd
hh ll
ee ff
ff
34
44
54
64
74
9E64
4E
5E
6E
7E
ee ff
ff
dd
ff
ff
dd
ff
ff
dd dd
dd
ii dd
dd
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 5 of 7)
2
3
4
4
3
3
5
4
5
1
1
5
4
6
5
1
1
5
4
6
5
5
4
5
42
5
30 dd
40
50
60 ff
70
9E60 ff
5
1
1
5
4
6
NEG opr8a
NEGA
NEGX
NEG oprx8,X
NEG ,X
NEG oprx8,SP
Negate
(Two’s Complement)
NOP
No Operation
Uses 1 Bus Cycle
– – – – – – INH
9D
1
NSA
Nibble Swap
Accumulator
A ← (A[3:0]:A[7:4])
– – – – – – INH
62
1
IMM
DIR
EXT
↕ – IX2
IX1
IX
SP2
SP1
AA
BA
CA
DA
EA
FA
9EDA
9EEA
Push (A); SP ← (SP) – 0x0001
– – – – – – INH
87
2
Push (H); SP ← (SP) – 0x0001
– – – – – – INH
8B
2
Push (X); SP ← (SP) – 0x0001
– – – – – – INH
89
2
SP ← (SP + 0x0001); Pull (A)
– – – – – – INH
86
3
SP ← (SP + 0x0001); Pull (H)
– – – – – – INH
8A
3
SP ← (SP + 0x0001); Pull (X)
– – – – – – INH
88
3
39 dd
49
59
69 ff
79
9E69 ff
5
1
1
5
4
6
ORA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
PSHA
PSHH
PSHX
PULA
PULH
PULX
ROL opr8a
ROLA
ROLX
ROL oprx8,X
ROL ,X
ROL oprx8,SP
Inclusive OR Accumulator
and Memory
Push Accumulator onto
Stack
Push H (Index Register
High) onto Stack
Push X (Index Register
Low) onto Stack
Pull Accumulator from
Stack
Pull H (Index Register
High) from Stack
Pull X (Index Register
Low) from Stack
Rotate Left through Carry
A ← (A) | (M)
– – ↕ ↕
0 – – ↕
↕ – – ↕
C
b7
b0
↕
DIR
INH
↕ INH
IX1
IX
SP1
DIR
INH
↕ INH
IX1
IX
SP1
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
MC9S08AC16 Series Data Sheet, Rev. 0
126
PRELIMINARY
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV2)
V H I N Z C
ROR opr8a
RORA
RORX
ROR oprx8,X
ROR ,X
ROR oprx8,SP
Rotate Right through
Carry
RSP
Reset Stack Pointer
RTI
Return from Interrupt
RTS
Return from Subroutine
SBC
SBC
SBC
SBC
SBC
SBC
SBC
SBC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
SEC
SEI
STA
STA
STA
STA
STA
STA
STA
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Subtract with Carry
I←1
STOP
Enable Interrupts:
Stop Processing
Refer to MCU
Documentation
SWI
A ← (A) – (M) – (C)
Set Interrupt Mask Bit
Store H:X (Index Reg.)
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
SP ← 0xFF
(High Byte Not Affected)
SP ← (SP) + 0x0001; Pull (CCR)
SP ← (SP) + 0x0001; Pull (A)
SP ← (SP) + 0x0001; Pull (X)
SP ← (SP) + 0x0001; Pull (PCH)
SP ← (SP) + 0x0001; Pull (PCL)
SP ← SP + 0x0001; Pull (PCH)
SP ← SP + 0x0001; Pull (PCL)
C←1
Store Accumulator in
Memory
Store X (Low 8 Bits of
Index Register)
in Memory
Subtract
Software Interrupt
36 dd
46
56
66 ff
76
9E66 ff
5
1
1
5
4
6
– – – – – – INH
9C
1
↕
↕ INH
80
9
– – – – – – INH
81
6
IMM
DIR
EXT
↕ IX2
IX1
IX
SP2
SP1
A2
B2
C2
D2
E2
F2
9ED2
9EE2
– – – – – 1 INH
– – 1 – – – INH
99
9B
DIR
EXT
IX2
↕ – IX1
IX
SP2
SP1
DIR
↕ – EXT
SP1
B7
C7
D7
E7
F7
9ED7
9EE7
35
96
9EFF
– – 0 – – – INH
8E
DIR
EXT
IX2
↕ – IX1
IX
SP2
SP1
IMM
DIR
EXT
↕ ↕ IX2
IX1
IX
SP2
SP1
BF
CF
DF
EF
FF
9EDF
9EEF
A0
B0
C0
D0
E0
F0
9ED0
9EE0
– – 1 – – – INH
83
↕ – – ↕
↕
b0
Set Carry Bit
STHX opr8a
STHX opr16a
STHX oprx8,SP
STX
STX
STX
STX
STX
STX
STX
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
C
b7
M ← (A)
(M:M + 0x0001) ← (H:X)
I bit ← 0; Stop Processing
M ← (X)
A ← (A) – (M)
PC ← (PC) + 0x0001
Push (PCL); SP ← (SP) – 0x0001
Push (PCH); SP ← (SP) – 0x0001
Push (X); SP ← (SP) – 0x0001
Push (A); SP ← (SP) – 0x0001
Push (CCR); SP ← (SP) – 0x0001
I ← 1;
PCH ← Interrupt Vector High Byte
PCL ← Interrupt Vector Low Byte
↕
↕
↕
↕ – – ↕
0 – – ↕
0 – – ↕
0 – – ↕
↕ – – ↕
↕
↕
DIR
INH
↕ INH
IX1
IX
SP1
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 6 of 7)
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
1
1
dd
hh ll
ee ff
ff
ee ff
ff
dd
hh ll
ff
3
4
4
3
2
5
4
4
5
5
2+
dd
hh ll
ee ff
ff
ee ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
3
4
4
3
2
5
4
2
3
4
4
3
3
5
4
11
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
127
Chapter 7 Central Processor Unit (S08CPUV2)
Description
V H I N Z C
TAP
TAX
TPA
Transfer Accumulator to
CCR
Transfer Accumulator to
X (Index Register Low)
Transfer CCR to
Accumulator
CCR ← (A)
↕
↕
↕
↕
↕
Bus Cycles1
Operation
Operand
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 7-2. HCS08 Instruction Set Summary (Sheet 7 of 7)
↕ INH
84
1
X ← (A)
– – – – – – INH
97
1
A ← (CCR)
– – – – – – INH
85
1
DIR
INH
↕ – INH
IX1
IX
SP1
3D dd
4D
5D
6D ff
7D
9E6D ff
4
1
1
4
3
5
TST opr8a
TSTA
TSTX
TST oprx8,X
TST ,X
TST oprx8,SP
Test for Negative or Zero
(M) – 0x00
(A) – 0x00
(X) – 0x00
(M) – 0x00
(M) – 0x00
(M) – 0x00
TSX
Transfer SP to Index Reg.
H:X ← (SP) + 0x0001
– – – – – – INH
95
2
TXA
Transfer X (Index Reg.
Low) to Accumulator
A ← (X)
– – – – – – INH
9F
1
SP ← (H:X) – 0x0001
– – – – – – INH
94
2
I bit ← 0; Halt CPU
– – 0 – – – INH
8F
2+
TXS
Transfer Index Reg. to SP
WAIT
Enable Interrupts; Wait
for Interrupt
1
0 – – ↕
Bus clock frequency is one-half of the CPU clock frequency.
MC9S08AC16 Series Data Sheet, Rev. 0
128
PRELIMINARY
Freescale Semiconductor
Chapter 7 Central Processor Unit (S08CPUV2)
Table 7-3. Opcode Map (Sheet 1 of 2)
Bit-Manipulation
00
5 10
5
BRSET0
3
01
BRCLR1
3
04
BRSET2
3
05
3
07
BRSET4
3
09
BRSET5
3
0B
BRSET6
3
0D
BRCLR6
3
0E
BRSET7
3
0F
BRCLR7
3
INH
IMM
DIR
EXT
DD
IX+D
INC
REL 2
3 3D
DIR 2
5 2F
CPHX
REL 3
3 3F
BIH
CLR
REL 2
REL
IX
IX1
IX2
IMD
DIX+
MOV
EXT 3
5 4F
DIR 1
ASR
INH 2
1 68
INH 1
Relative
Indexed, No Offset
Indexed, 8-Bit Offset
Indexed, 16-Bit Offset
IMM to DIR
DIR to IX+
ROL
INH 2
1 6A
DEC
DBNZ
DBNZ
INC
INH 2
1 6D
INC
IX1 1
4 7D
TST
INH 2
5 6E
MOV
CLR
INH 1
2
BD
BSR
INH 2
AE
Page 2
WAIT
IX 1
5
1
JSR
REL 2
2 BE
LDX
2
AF
TXA
INH 2
AIX
LDX
DIR 3
3 CF
STX
IMM 2
EXT 3
4 DF
STX
DIR 3
EXT 3
Opcode in
Hexadecimal F0
EOR
ADC
IX2 2
IX
2
STA
IX
3
EOR
IX
3
ADC
IX1 1
3 FA
ORA
IX
3
ORA
IX1 1
3 FB
ADD
JSR
LDX
IX1 1
3 FF
IX
5
JSR
IX1 1
3 FE
IX1 1
IX
3
JMP
IX1 1
5 FD
STX
IX
3
ADD
IX1 1
3 FC
JMP
IX2 2
4 EF
STX
IX
3
LDA
IX1 1
3 F9
IX2 2
4 EE
LDX
BIT
IX1 1
3 F8
IX2 2
6 ED
JSR
EXT 3
4 DE
IX
3
STA
IX2 2
4 EC
JMP
EXT 3
6 DD
JSR
DIR 3
3 CE
LDX
IMM 2
2 BF
Stack Pointer, 8-Bit Offset
Stack Pointer, 16-Bit Offset
Indexed, No Offset with
Post Increment
Indexed, 1-Byte Offset with
Post Increment
JMP
DIR 3
5 CD
AND
IX1 1
3 F7
IX2 2
4 EB
ADD
EXT 3
4 DC
IX
3
LDA
IX2 2
4 EA
ORA
EXT 3
4 DB
ADD
JMP
INH
1 AD
INH
2+ 9F
ORA
CPX
IX1 1
3 F6
IX2 2
4 E9
ADC
EXT 3
4 DA
IX
3
BIT
IX2 2
4 E8
EOR
IX
3
SBC
IX1 1
3 F5
STA
ADC
DIR 3
3 CC
AND
IX2 2
4 E7
EXT 3
4 D9
CMP
IX1 1
3 F4
IX2 2
4 E6
EXT 3
4 D8
EOR
DIR 3
3 CB
ADD
IMM 2
BC
RSP
1
2+ 9E
STOP
IMM 2
2 BB
CPX
LDA
STA
IX
3
IX1 1
3 F3
IX2 2
4 E5
EXT 3
4 D7
DIR 3
3 CA
ORA
ADD
INH 2
1
NOP
IX
5 8E
ADC
SBC
BIT
LDA
DIR 3
3 C9
IMM 2
2 BA
ORA
SEI
INH 1
9D
IMD 2
IX+D 1
5 7F
4 8F
IX1 1
ADC
INH 2
1 AB
INH 1
1 9C
CLRH
IX 1
3
MOV
CLR
INH 2
INH 1
2 9B
EOR
AND
3
SUB
IX1 1
3 F2
IX2 2
4 E4
EXT 3
4 D6
DIR 3
3 C8
IMM 2
2 B9
INH 2
1 AA
CLI
TST
IX1 1
4 7E
MOV
CLRX
SEC
INH 1
3 9A
PSHH
IX 1
4 8C
EOR
CPX
BIT
STA
CMP
IX2 2
4 E3
EXT 3
4 D5
DIR 3
3 C7
IMM 2
2 B8
INH 2
1 A9
PULH
IX 1
6 8B
IX1 2
5 7C
CLC
INH 1
2 99
AND
LDA
AIS
INH 2
1 A8
SBC
F0
IX1 1
3 F1
IX2 2
4 E2
EXT 3
4 D4
DIR 3
3 C6
IMM 2
2 B7
TAX
CPX
BIT
LDA
CMP
EXT 3
4 D3
DIR 3
3 C5
IMM 2
2 B6
EXT 2
1 A7
INH 1
3 98
PSHX
IX 1
4 8A
IX1 1
7 7B
INH 3
1 6C
IX1+
ROL
DEC
INH 3
2 97
PULX
IX 1
4 89
IX1 1
5 7A
INH 2
4 6B
SP1
SP2
IX+
LSL
STHX
PSHA
IX 1
4 88
IX1 1
5 79
DD 2
DIX+ 3
1 5F
1 6F
CLRA
ASR
LSL
INH 2
1 69
PULA
IX 1
4 87
IX1 1
5 78
TSTX
INH 1
5 5E
ROR
AND
BIT
INH 2
5 A6
SBC
3
SUB
IX2 2
4 E1
EXT 3
4 D2
DIR 3
3 C4
IMM 2
2 B5
TSX
INH 1
3 96
CPX
AND
CMP
E0
SUB
EXT 3
4 D1
DIR 3
3 C3
IMM 2
2 B4
INH 2
2 A5
TPA
DIR 1
4 86
IX1 1
5 77
INCX
INH 1
1 5D
TSTA
DIR 1
6 4E
INH 2
1 67
DBNZX
INH 2
1 5C
INCA
DIR 1
4 4D
TST
REL 2
3 3E
BIL
DBNZA
DIR 2
5 4C
ROR
DECX
INH 1
4 5B
CPHX
TXS
INH 1
1 95
SBC
CPX
SUB
DIR 3
3 C2
IMM 2
2 B3
REL 2
2 A4
TAP
IX 1
5 85
IMM 2
5 76
ROLX
INH 1
1 5A
DECA
DIR 1
7 4B
DBNZ
BMS
DIR 2
5 2E
Inherent
Immediate
Direct
Extended
DIR to DIR
IX+ to DIR
DEC
CPHX
LSLX
INH 1
1 59
LSR
IX1 1
3 75
DIR 3
1 66
ASRX
INH 1
1 58
ROLA
DIR 1
5 4A
BMC
DIR 2
5 2D
DIR 2
ROL
REL 3
3 3C
INH 1
1 57
LSLA
DIR 1
5 49
REL 2
3 3B
BMI
DIR 2
5 2C
BCLR7
DIR 2
LSL
LSR
CMP
SBC
BLE
Register/Memory
C0
4 D0
4
DIR 3
3 C1
IMM 2
2 B2
REL 2
3 A3
INH 2
1 94
3
SUB
CMP
BGT
SWI
B0
IMM 2
2 B1
REL 2
3 A2
INH 2
11 93
IX 1
4 84
2
SUB
BLT
INH 2
5+ 92
BGND
COM
A0
REL 2
3 A1
RTS
INH 1
4 83
IX1 1
5 74
INH 2
4 65
RORX
ASRA
DIR 1
5 48
REL 2
3 3A
BPL
BSET7
DIR 2
5 1F
ASR
COM
LDHX
IMM 2
1 56
RORA
DIR 1
5 47
BHCS
DIR 2
5 2B
BCLR6
DIR 2
5 1E
ROR
REL 2
3 39
DIR 2
5 2A
LDHX
DIR 3
5 46
BHCC
DIR 2
5 29
BSET6
DIR 2
5 1D
STHX
DAA
3
BGE
INH 2
6 91
IX+ 1
1 82
INH 1
5 73
INH 2
1 64
RTI
CBEQ
NSA
INH 1
1 63
Control
9 90
80
IX 1
5 81
IX1+ 2
1 72
LSRX
INH 1
3 55
4
NEG
CBEQ
COMX
INH 1
1 54
LSRA
DIR 1
4 45
REL 2
3 38
BCLR5
DIR 2
5 1C
LSR
BEQ
INH 1
1 53
70
IX1 1
5 71
IMM 3
6 62
DIV
COMA
DIR 1
5 44
REL 2
3 37
BSET5
DIR 2
5 1B
BRCLR5
3
0C
BNE
DIR 2
5 28
BCLR4
DIR 2
5 1A
COM
REL 2
3 36
DIR 2
5 27
BSET4
DIR 2
5 19
BRCLR4
3
0A
BCS
MUL
5
NEG
INH 2
4 61
CBEQX
IMM 3
5 52
EXT 1
5 43
REL 2
3 35
DIR 2
5 26
CBEQA
LDHX
NEGX
INH 1
4 51
DIR 3
5 42
BCC
BCLR3
DIR 2
5 18
CBEQ
REL 2
3 34
DIR 2
5 25
BSET3
DIR 2
5 17
BRCLR3
3
08
BLS
NEGA
DIR 1
5 41
REL 3
3 33
DIR 2
5 24
BCLR2
DIR 2
5 16
BRSET3
DIR 2
5 23
Read-Modify-Write
1 50
1 60
40
NEG
REL 3
3 32
BHI
BSET2
DIR 2
5 15
BRCLR2
3
06
BRN
DIR 2
5 22
BCLR1
DIR 2
5 14
5
REL 2
3 31
BSET1
DIR 2
5 13
30
BRA
DIR 2
5 21
BCLR0
DIR 2
5 12
BRSET1
3
03
BSET0
DIR 2
5 11
BRCLR0
3
02
Branch
20
3
IX
3
LDX
IX
2
STX
IX
3 HCS08 Cycles
Instruction Mnemonic
IX Addressing Mode
SUB
Number of Bytes 1
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
129
Chapter 7 Central Processor Unit (S08CPUV2)
Table 7-3. Opcode Map (Sheet 2 of 2)
Bit-Manipulation
Branch
Read-Modify-Write
9E60
Control
Register/Memory
9ED0 5
6
NEG
CMP
SP1
CMP
4
SP2 3
SP1
9ED2 5 9EE2 4
SBC
9E63
SBC
4
SP2 3
SP1
9ED3 5 9EE3 4 9EF3
6
COM
CPX
3
SP1
9E64
6
CPX
AND
SP1
SP1
AND
4
SP2 3
SP1
9ED5 5 9EE5 4
BIT
BIT
6
4
SP2 3
SP1
9ED6 5 9EE6 4
3
SP1
9E67
6
4
SP2 3
SP1
9ED7 5 9EE7 4
9E66
6
CPHX
4
SP2 3
SP1 3
9ED4 5 9EE4 4
LSR
3
4
SUB
4
SP2 3
SP1
9ED1 5 9EE1 4
CBEQ
4
9EE0
SUB
3
SP1
9E61
6
ROR
LDA
ASR
LDA
STA
3
SP1
9E68
6
STA
4
SP2 3
SP1
9ED8 5 9EE8 4
LSL
EOR
3
SP1
9E69
6
EOR
4
SP2 3
SP1
9ED9 5 9EE9 4
ROL
ADC
3
SP1
9E6A 6
ADC
4
SP2 3
SP1
9EDA 5 9EEA 4
DEC
ORA
3
SP1
9E6B 8
ORA
4
SP2 3
SP1
9EDB 5 9EEB 4
DBNZ
ADD
4
SP1
9E6C 6
4
ADD
SP2 3
SP1
INC
3
SP1
9E6D 5
TST
3
SP1
9EAE
5
9EBE
LDHX
2
9E6F
IX 4
6
9ECE
LDHX
5
9EDE
LDHX
IX2 3
6
CLR
3
INH
IMM
DIR
EXT
DD
IX+D
Inherent
Immediate
Direct
Extended
DIR to DIR
IX+ to DIR
REL
IX
IX1
IX2
IMD
DIX+
Relative
Indexed, No Offset
Indexed, 8-Bit Offset
Indexed, 16-Bit Offset
IMM to DIR
DIR to IX+
SP1
SP2
IX+
IX1+
5
9EEE
LDX
4
9EFE
LDX
5
LDHX
IX1 4
SP2 3
SP1 3
SP1
9EDF 5 9EEF 4 9EFF 5
STX
SP1
4
SP2 3
STX
SP1 3
STHX
SP1
Stack Pointer, 8-Bit Offset
Stack Pointer, 16-Bit Offset
Indexed, No Offset with
Post Increment
Indexed, 1-Byte Offset with
Post Increment
Note: All Sheet 2 Opcodes are Preceded by the Page 2 Prebyte (9E)
Prebyte (9E) and Opcode in
Hexadecimal 9E60
6
HCS08 Cycles
Instruction Mnemonic
SP1 Addressing Mode
NEG
Number of Bytes 3
MC9S08AC16 Series Data Sheet, Rev. 0
130
PRELIMINARY
Freescale Semiconductor
Chapter 8
Internal Clock Generator (S08ICGV4)
The internal clock generation (ICG) module is used to generate the system clocks for the MC9S08AC16
Series MCU. The analog supply lines VDDA and VSSA are internally derived from the MCU’s VDD and
VSS pins. Electrical parametric data for the ICG may be found in Appendix A, “Electrical Characteristics
and Timing Specifications.”
TPMCLK
SYSTEM
CONTROL
LOGIC
ICGERCLK
RTI
FFE
TPM1
TPM2
IIC1
SCI1
SCI2
SPI1
RAM
FLASH
÷2
ICG
XCLK*
COP
ICGOUT
÷2
1 kHz
BUSCLK
ICGLCLK*
CPU
BDC
TPM3
* ICGLCLK is the alternate BDC clock source for the MC9S08AC16 Series.
* XCLK is the fixed-frequency clock.
ADC1
ADC has min and max
frequency requirements.
See the Electricals appendix
and the ADC chapter.
FLASH has frequency
requirements for program
and erase operation.
See the Electricals
appendix.
Figure 8-1. System Clock Distribution Diagram
NOTE
Freescale Semiconductor recommends that FLASH location 0xFFBE be
reserved to store a nonvolatile version of ICGTRM. This will allow
debugger and programmer vendors to perform a manual trim operation and
store the resultant ICGTRM value for users to access at a later time.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
131
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 8 Internal Clock Generator (S08ICGV4)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 8-2. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
132
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.1
Introduction
The ICG provides multiple options for clock sources. This offers a user great flexibility when making
choices between cost, precision, current draw, and performance. As seen in Figure 8-3, the ICG consists
of four functional blocks. Each of these is briefly described here and then in more detail in a later section.
• Oscillator block — The oscillator block provides means for connecting an external crystal or
resonator. Two frequency ranges are software selectable to allow optimal startup and stability.
Alternatively, the oscillator block can be used to route an external square wave to the system clock.
External sources can provide a very precise clock source. The oscillator is capable of being
configured for low power mode or high amplitude mode as selected by HGO.
• Internal reference generator — The internal reference generator consists of two controlled clock
sources. One is designed to be approximately 8 MHz and can be selected as a local clock for the
background debug controller. The other internal reference clock source is typically 243 kHz and
can be trimmed for finer accuracy via software when a precise timed event is input to the MCU.
This provides a highly reliable, low-cost clock source.
• Frequency-locked loop — A frequency-locked loop (FLL) stage takes either the internal or
external clock source and multiplies it to a higher frequency. Status bits provide information when
the circuit has achieved lock and when it falls out of lock. Additionally, this block can monitor the
external reference clock and signals whether the clock is valid or not.
• Clock select block — The clock select block provides several switch options for connecting
different clock sources to the system clock tree. ICGDCLK is the multiplied clock frequency out
of the FLL, ICGERCLK is the reference clock frequency from the crystal or external clock source,
and FFE (fixed frequency enable) is a control signal used to control the system fixed frequency
clock (XCLK). ICGLCLK is the clock source for the background debug controller (BDC).
8.1.1
Features
The module is intended to be very user friendly with many of the features occurring automatically without
user intervention. To quickly configure the module, go to Section 8.5, “Initialization/Application
Information” and pick an example that best suits the application needs.
Features of the ICG and clock distribution system:
• Several options for the primary clock source allow a wide range of cost, frequency, and precision
choices:
— 32 kHz–100 kHz crystal or resonator
— 1 MHz–16 MHz crystal or resonator
— External clock
— Internal reference generator
• Defaults to self-clocked mode to minimize startup delays
• Frequency-locked loop (FLL) generates 8 MHz to 40 MHz (for bus rates up to 20 MHz)
— Uses external or internal clock as reference frequency
• Automatic lockout of non-running clock sources
• Reset or interrupt on loss of clock or loss of FLL lock
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
133
Chapter 8 Internal Clock Generator (S08ICGV4)
•
•
•
•
•
•
•
8.1.2
Digitally-controlled oscillator (DCO) preserves previous frequency settings, allowing fast
frequency lock when recovering from stop3 mode
DCO will maintain operating frequency during a loss or removal of reference clock
Post-FLL divider selects 1 of 8 bus rate divisors (/1 through /128)
Separate self-clocked source for real-time interrupt
Trimmable internal clock source supports SCI communications without additional external
components
Automatic FLL engagement after lock is acquired
External oscillator selectable for low power or high gain
Modes of Operation
This is a high-level description only. Detailed descriptions of operating modes are contained in
Section 8.4, “Functional Description.”
• Mode 1 — Off
The output clock, ICGOUT, is static. This mode may be entered when the STOP instruction is
executed.
• Mode 2 — Self-clocked (SCM)
Default mode of operation that is entered immediately after reset. The ICG’s FLL is open loop and
the digitally controlled oscillator (DCO) is free running at a frequency set by the filter bits.
• Mode 3 — FLL engaged internal (FEI)
In this mode, the ICG’s FLL is used to create frequencies that are programmable multiples of the
internal reference clock.
— FLL engaged internal unlocked is a transition state that occurs while the FLL is attempting to
lock. The FLL DCO frequency is off target and the FLL is adjusting the DCO to match the
target frequency.
— FLL engaged internal locked is a state that occurs when the FLL detects that the DCO is locked
to a multiple of the internal reference.
• Mode 4 — FLL bypassed external (FBE)
In this mode, the ICG is configured to bypass the FLL and use an external clock as the clock source.
• Mode 5 — FLL engaged external (FEE)
The ICG’s FLL is used to generate frequencies that are programmable multiples of the external
clock reference.
— FLL engaged external unlocked is a transition state that occurs while the FLL is attempting to
lock. The FLL DCO frequency is off target and the FLL is adjusting the DCO to match the
target frequency.
— FLL engaged external locked is a state which occurs when the FLL detects that the DCO is
locked to a multiple of the internal reference.
MC9S08AC16 Series Data Sheet, Rev. 0
134
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.1.3
Block Diagram
Figure 8-3 is a top-level diagram that shows the functional organization of the internal clock generation
(ICG) module. This section includes a general description and a feature list.
EXTAL
OSCILLATOR (OSC)
WITH EXTERNAL REF
SELECT
ICG
CLOCK
SELECT
ICGERCLK
XTAL
ICGDCLK
FREQUENCY
LOCKED
LOOP (FLL)
REF
SELECT
VDDA
(SEE NOTE 2)
DCO
OUTPUT
CLOCK
SELECT
/R
ICGOUT
LOSS OF LOCK
AND CLOCK DETECTOR
V SSA
(SEE NOTE 2)
FIXED
CLOCK
SELECT
IRG
INTERNAL TYP 243 kHz
REFERENCE
8 MHz
GENERATORS
RG
FFE
ICGIRCLK
LOCAL CLOCK FOR OPTIONAL USE WITH BDC
ICGLCLK
NOTES:
1. See Section 8.2, “External Signal Description” for specific use of ICGOUT, FFE, ICGLCLK, ICGERCLK
2. Not all HCS08 microcontrollers have unique supply pins for the ICG. See the device pin assignments.
Figure 8-3. ICG Block Diagram
8.2
External Signal Description
The oscillator pins are used to provide an external clock source for the MCU. The oscillator pins are gain
controlled in low-power mode (default). Oscillator amplitudes in low-power mode are limited to
approximately 1 V, peak-to-peak.
8.2.1
EXTAL — External Reference Clock / Oscillator Input
If upon the first write to ICGC1, either the FEE mode or FBE mode is selected, this pin functions as either
the external clock input or the input of the oscillator circuit as determined by REFS. If upon the first write
to ICGC1, either the FEI mode or SCM mode is selected, this pin is not used by the ICG.
8.2.2
XTAL — Oscillator Output
If upon the first write to ICGC1, either the FEE mode or FBE mode is selected, this pin functions as the
output of the oscillator circuit. If upon the first write to ICGC1, either the FEI mode or SCM mode is
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
135
Chapter 8 Internal Clock Generator (S08ICGV4)
selected, this pin is not used by the ICG. The oscillator is capable of being configured to provide a higher
amplitude output for improved noise immunity. This mode of operation is selected by HGO = 1.
8.2.3
External Clock Connections
If an external clock is used, then the pins are connected as shown Figure 8-4.
ICG
EXTAL
XTAL
VSS
NOT CONNECTED
CLOCK INPUT
Figure 8-4. External Clock Connections
8.2.4
External Crystal/Resonator Connections
If an external crystal/resonator frequency reference is used, then the pins are connected as shown in
Figure 8-5. Recommended component values are listed in the Electrical Characteristics chapter.
ICG
EXTAL
VSS
XTAL
RS
C1
C2
RF
CRYSTAL OR RESONATOR
Figure 8-5. External Frequency Reference Connection
MC9S08AC16 Series Data Sheet, Rev. 0
136
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.3
Register Definition
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all ICG registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
8.3.1
R
ICG Control Register 1 (ICGC1)
7
6
5
HGO1
RANGE
REFS
0
1
0
4
3
2
1
OSCSTEN
LOCD
1
0
0
0
CLKS
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 8-6. ICG Control Register 1 (ICGC1)
1
This bit can be written only once after reset. Additional writes are ignored.
Table 8-1. ICGC1 Register Field Descriptions
Field
7
HGO
Description
High Gain Oscillator Select — The HGO bit is used to select between low power operation and high gain
operation for improved noise immunity. This bit is write-once after reset.
0 Oscillator configured for low power operation.
1 Oscillator configured for high gain operation.
6
RANGE
Frequency Range Select — The RANGE bit controls the oscillator, reference divider, and FLL loop prescaler
multiplication factor (P). It selects one of two reference frequency ranges for the ICG. The RANGE bit is
write-once after a reset. The RANGE bit only has an effect in FLL engaged external and FLL bypassed external
modes.
0 Oscillator configured for low frequency range. FLL loop prescale factor P is 64.
1 Oscillator configured for high frequency range. FLL loop prescale factor P is 1.
5
REFS
External Reference Select — The REFS bit controls the external reference clock source for ICGERCLK. The
REFS bit is write-once after a reset.
0 External clock requested.
1 Oscillator using crystal or resonator requested.
4:3
CLKS
Clock Mode Select — The CLKS bits control the clock mode as described below. If FLL bypassed external is
requested, it will not be selected until ERCS = 1. If the ICG enters off mode, the CLKS bits will remain
unchanged. Writes to the CLKS bits will not take effect if a previous write is not complete.
00 Self-clocked
01 FLL engaged, internal reference
10 FLL bypassed, external reference
11 FLL engaged, external reference
The CLKS bits are writable at any time, unless the first write after a reset was CLKS = 0X, the CLKS bits cannot
be written to 1X until after the next reset (because the EXTAL pin was not reserved).
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
137
Chapter 8 Internal Clock Generator (S08ICGV4)
Table 8-1. ICGC1 Register Field Descriptions (continued)
Field
2
OSCSTEN
1
LOCD
Description
Enable Oscillator in Off Mode — The OSCSTEN bit controls whether or not the oscillator circuit remains
enabled when the ICG enters off mode. This bit has no effect if HGO = 1 and RANGE = 1.
0 Oscillator disabled when ICG is in off mode unless ENABLE is high, CLKS = 10, and REFST = 1.
1 Oscillator enabled when ICG is in off mode, CLKS = 1X and REFST = 1.
Loss of Clock Disable
0 Loss of clock detection enabled.
1 Loss of clock detection disabled.
MC9S08AC16 Series Data Sheet, Rev. 0
138
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.3.2
ICG Control Register 2 (ICGC2)
7
6
5
4
3
2
1
0
R
LOLRE
MFD
LOCRE
RFD
W
Reset
0
0
0
0
0
0
0
0
Figure 8-7. ICG Control Register 2 (ICGC2)
Table 8-2. ICGC2 Register Field Descriptions
Field
Description
7
LOLRE
Loss of Lock Reset Enable — The LOLRE bit determines what type of request is made by the ICG following a
loss of lock indication. The LOLRE bit only has an effect when LOLS is set.
0
Generate an interrupt request on loss of lock.
1
Generate a reset request on loss of lock.
6:4
MFD
Multiplication Factor — The MFD bits control the programmable multiplication factor in the FLL loop. The value
specified by the MFD bits establishes the multiplication factor (N) applied to the reference frequency. Writes to
the MFD bits will not take effect if a previous write is not complete. Select a low enough value for N such that
fICGDCLK does not exceed its maximum specified value.
000 Multiplication factor = 4
001 Multiplication factor = 6
010 Multiplication factor = 8
011 Multiplication factor = 10
100 Multiplication factor = 12
101 Multiplication factor = 14
110 Multiplication factor = 16
111 Multiplication factor = 18
3
LOCRE
Loss of Clock Reset Enable — The LOCRE bit determines how the system manages a loss of clock condition.
0
Generate an interrupt request on loss of clock.
1
Generate a reset request on loss of clock.
2:0
RFD
Reduced Frequency Divider — The RFD bits control the value of the divider following the clock select circuitry.
The value specified by the RFD bits establishes the division factor (R) applied to the selected output clock source.
Writes to the RFD bits will not take effect if a previous write is not complete.
000 Division factor = 1
001 Division factor = 2
010 Division factor = 4
011 Division factor = 8
100 Division factor = 16
101 Division factor = 32
110 Division factor = 64
111 Division factor = 128
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
139
Chapter 8 Internal Clock Generator (S08ICGV4)
8.3.3
ICG Status Register 1 (ICGS1)
7
R
6
CLKST
5
4
3
2
1
0
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
W
Reset
1
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 8-8. ICG Status Register 1 (ICGS1)
Table 8-3. ICGS1 Register Field Descriptions
Field
Description
7:6
CLKST
Clock Mode Status — The CLKST bits indicate the current clock mode. The CLKST bits don’t update
immediately after a write to the CLKS bits due to internal synchronization between clock domains.
00 Self-clocked
01 FLL engaged, internal reference
10 FLL bypassed, external reference
11 FLL engaged, external reference
5
REFST
Reference Clock Status — The REFST bit indicates which clock reference is currently selected by the
Reference Select circuit.
0 External Clock selected.
1 Crystal/Resonator selected.
4
LOLS
FLL Loss of Lock Status — The LOLS bit is a sticky indication of FLL lock status.
0 FLL has not unexpectedly lost lock since LOLS was last cleared.
1 FLL has unexpectedly lost lock since LOLS was last cleared, LOLRE determines action taken.FLL has
unexpectedly lost lock since LOLS was last cleared, LOLRE determines action taken.
3
LOCK
FLL Lock Status — The LOCK bit indicates whether the FLL has acquired lock. The LOCK bit is cleared in off,
self-clocked, and FLL bypassed modes.
0 FLL is currently unlocked.
1 FLL is currently locked.
2
LOCS
Loss Of Clock Status — The LOCS bit is an indication of ICG loss of clock status.
0 ICG has not lost clock since LOCS was last cleared.
1 ICG has lost clock since LOCS was last cleared, LOCRE determines action taken.
1
ERCS
External Reference Clock Status — The ERCS bit is an indication of whether or not the external reference
clock (ICGERCLK) meets the minimum frequency requirement.
0 External reference clock is not stable, frequency requirement is not met.
1 External reference clock is stable, frequency requirement is met.
0
ICGIF
ICG Interrupt Flag — The ICGIF read/write flag is set when an ICG interrupt request is pending. It is cleared by
a reset or by reading the ICG status register when ICGIF is set and then writing a logic 1 to ICGIF. If another ICG
interrupt occurs before the clearing sequence is complete, the sequence is reset so ICGIF would remain set after
the clear sequence was completed for the earlier interrupt. Writing a logic 0 to ICGIF has no effect.
0 No ICG interrupt request is pending.
1 An ICG interrupt request is pending.
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.3.4
R
ICG Status Register 2 (ICGS2)
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
DCOS
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 8-9. ICG Status Register 2 (ICGS2)
Table 8-4. ICGS2 Register Field Descriptions
Field
Description
0
DCOS
DCO Clock Stable — The DCOS bit is set when the DCO clock (ICG2DCLK) is stable, meaning the count error
has not changed by more than nunlock for two consecutive samples and the DCO clock is not static. This bit is
used when exiting off state if CLKS = X1 to determine when to switch to the requested clock mode. It is also used
in self-clocked mode to determine when to start monitoring the DCO clock. This bit is cleared upon entering the
off state.
0 DCO clock is unstable.
1 DCO clock is stable.
8.3.5
R
ICG Filter Registers (ICGFLTU, ICGFLTL)
7
6
5
4
0
0
0
0
3
2
1
0
0
0
FLT
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 8-10. ICG Upper Filter Register (ICGFLTU)
Table 8-5. ICGFLTU Register Field Descriptions
Field
Description
3:0
FLT
Filter Value — The FLT bits indicate the current filter value, which controls the DCO frequency. The FLT bits are
read only except when the CLKS bits are programmed to self-clocked mode (CLKS = 00). In self-clocked mode,
any write to ICGFLTU updates the current 12-bit filter value. Writes to the ICGFLTU register will not affect FLT if
a previous latch sequence is not complete.
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Chapter 8 Internal Clock Generator (S08ICGV4)
7
6
5
4
3
2
1
0
0
0
0
0
R
FLT
W
Reset
1
1
0
0
Figure 8-11. ICG Lower Filter Register (ICGFLTL)
Table 8-6. ICGFLTL Register Field Descriptions
Field
Description
7:0
FLT
Filter Value — The FLT bits indicate the current filter value, which controls the DCO frequency. The FLT bits are
read only except when the CLKS bits are programmed to self-clocked mode (CLKS = 00). In self-clocked mode,
any write to ICGFLTU updates the current 12-bit filter value. Writes to the ICGFLTU register will not affect FLT if
a previous latch sequence is not complete. The filter registers show the filter value (FLT).
8.3.6
ICG Trim Register (ICGTRM)
7
6
5
4
3
2
1
0
R
TRIM
W
POR
1
0
0
0
0
0
0
0
Reset:
U
U
U
U
U
U
U
U
U = Unaffected by MCU reset
Figure 8-12. ICG Trim Register (ICGTRM)
Table 8-7. ICGTRM Register Field Descriptions
Field
7
TRIM
Description
ICG Trim Setting — The TRIM bits control the internal reference generator frequency. They allow a ±25%
adjustment of the nominal (POR) period. The bit’s effect on period is binary weighted (i.e., bit 1 will adjust twice
as much as changing bit 0). Increasing the binary value in TRIM will increase the period and decreasing the value
will decrease the period.
8.4
Functional Description
This section provides a functional description of each of the five operating modes of the ICG. Also
discussed are the loss of clock and loss of lock errors and requirements for entry into each mode. The ICG
is very flexible, and in some configurations, it is possible to exceed certain clock specifications. When
using the FLL, configure the ICG so that the frequency of ICGDCLK does not exceed its maximum value
to ensure proper MCU operation.
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.1
Off Mode (Off)
Normally when the CPU enters stop mode, the ICG will cease all clock activity and is in the off state.
However there are two cases to consider when clock activity continues while the CPU is in stop mode,
8.4.1.1
BDM Active
When the BDM is enabled, the ICG continues activity as originally programmed. This allows access to
memory and control registers via the BDC controller.
8.4.1.2
OSCSTEN Bit Set
When the oscillator is enabled in stop mode (OSCSTEN = 1), the individual clock generators are enabled
but the clock feed to the rest of the MCU is turned off. This option is provided to avoid long oscillator
startup times if necessary, or to run the RTI from the oscillator during stop3.
8.4.1.3
Stop/Off Mode Recovery
Upon the CPU exiting stop mode due to an interrupt, the previously set control bits are valid and the system
clock feed resumes. If FEE is selected, the ICG will source the internal reference until the external clock
is stable. If FBE is selected, the ICG will wait for the external clock to stabilize before enabling ICGOUT.
Upon the CPU exiting stop mode due to a reset, the previously set ICG control bits are ignored and the
default reset values applied. Therefore the ICG will exit stop in SCM mode configured for an
approximately 8 MHz DCO output (4 MHz bus clock) with trim value maintained. If using a crystal, 4096
clocks are detected prior to engaging ICGERCLK. This is incorporated in crystal start-up time.
8.4.2
Self-Clocked Mode (SCM)
Self-clocked mode (SCM) is the default mode of operation and is entered when any of the following
conditions occur:
• After any reset.
• Exiting from off mode when CLKS does not equal 10. If CLKS = X1, the ICG enters this state
temporarily until the DCO is stable (DCOS = 1).
• CLKS bits are written from X1 to 00.
• CLKS = 1X and ICGERCLK is not detected (both ERCS = 0 and LOCS = 1).
In this state, the FLL loop is open. The DCO is on, and the output clock signal ICGOUT frequency is given
by fICGDCLK / R. The ICGDCLK frequency can be varied from 8 MHz to 40 MHz by writing a new value
into the filter registers (ICGFLTH and ICGFLTL). This is the only mode in which the filter registers can
be written.
If this mode is entered due to a reset, fICGDCLK will default to fSelf_reset which is nominally 8 MHz. If this
mode is entered from FLL engaged internal, fICGDCLK will maintain the previous frequency.If this mode
is entered from FLL engaged external (either by programming CLKS or due to a loss of external reference
clock), fICGDCLK will maintain the previous frequency, but ICGOUT will double if the FLL was unlocked.
If this mode is entered from off mode, fICGDCLK will be equal to the frequency of ICGDCLK before
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Chapter 8 Internal Clock Generator (S08ICGV4)
entering off mode. If CLKS bits are set to 01 or 11 coming out of the Off state, the ICG enters this mode
until ICGDCLK is stable as determined by the DCOS bit. After ICGDCLK is considered stable, the ICG
automatically closes the loop by switching to FLL engaged (internal or external) as selected by the CLKS
bits.
CLKST
REFERENCE
DIVIDER (/7)
ICGIRCLK
CLKS
RFD
CLOCK
SELECT
CIRCUIT
REDUCED
FREQUENCY
DIVIDER (R)
RANGE
ICGOUT
ICGDCLK
FLT
MFD
1x
DIGITALLY
CONTROLLED
OSCILLATOR
2x
DIGITAL
LOOP
FILTER
SUBTRACTOR
FLL ANALOG
ICGERCLK
CLKST
FREQUENCYLOCKED
LOOP (FLL)
OVERFLOW
ICG2DCLK
PULSE
COUNTER
COUNTER ENABLE
RANGE
LOCK AND
LOSS OF CLOCK
DETECTOR
DCOS LOCK LOLS
LOCS ERCS
RESET AND
INTERRUPT
CONTROL
LOCD
IRQ
RESET
ICGIF LOLRE LOCRE
Figure 8-13. Detailed Frequency-Locked Loop Block Diagram
8.4.3
FLL Engaged, Internal Clock (FEI) Mode
FLL engaged internal (FEI) is entered when any of the following conditions occur:
• CLKS bits are written to 01
• The DCO clock stabilizes (DCOS = 1) while in SCM upon exiting the off state with CLKS = 01
In FLL engaged internal mode, the reference clock is derived from the internal reference clock
ICGIRCLK, and the FLL loop will attempt to lock the ICGDCLK frequency to the desired value, as
selected by the MFD bits.
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.4
FLL Engaged Internal Unlocked
FEI unlocked is a temporary state that is entered when FEI is entered and the count error (Δn) output from
the subtractor is greater than the maximum nunlock or less than the minimum nunlock, as required by the
lock detector to detect the unlock condition.
The ICG will remain in this state while the count error (Δn) is greater than the maximum nlock or less than
the minimum nlock, as required by the lock detector to detect the lock condition.
In this state the output clock signal ICGOUT frequency is given by fICGDCLK / R.
8.4.5
FLL Engaged Internal Locked
FLL engaged internal locked is entered from FEI unlocked when the count error (Δn), which comes from
the subtractor, is less than nlock (max) and greater than nlock (min) for a given number of samples, as
required by the lock detector to detect the lock condition. The output clock signal ICGOUT frequency is
given by fICGDCLK / R. In FEI locked, the filter value is updated only once every four comparison cycles.
The update made is an average of the error measurements taken in the four previous comparisons.
8.4.6
FLL Bypassed, External Clock (FBE) Mode
FLL bypassed external (FBE) is entered when any of the following conditions occur:
• From SCM when CLKS = 10 and ERCS is high
• When CLKS = 10, ERCS = 1 upon entering off mode, and off is then exited
• From FLL engaged external mode if a loss of DCO clock occurs and the external reference remains
valid (both LOCS = 1 and ERCS = 1)
In this state, the DCO and IRG are off and the reference clock is derived from the external reference clock,
ICGERCLK. The output clock signal ICGOUT frequency is given by fICGERCLK / R. If an external clock
source is used (REFS = 0), then the input frequency on the EXTAL pin can be anywhere in the range
0 MHz to 40 MHz. If a crystal or resonator is used (REFS = 1), then frequency range is either low for
RANGE = 0 or high for RANGE = 1.
8.4.7
FLL Engaged, External Clock (FEE) Mode
The FLL engaged external (FEE) mode is entered when any of the following conditions occur:
• CLKS = 11 and ERCS and DCOS are both high.
• The DCO stabilizes (DCOS = 1) while in SCM upon exiting the off state with CLKS = 11.
In FEE mode, the reference clock is derived from the external reference clock ICGERCLK, and the FLL
loop will attempt to lock the ICGDCLK frequency to the desired value, as selected by the MFD bits. To
run in FEE mode, there must be a working 32 kHz–100 kHz or 2 MHz–10 MHz external clock source. The
maximum external clock frequency is limited to 10 MHz in FEE mode to prevent over-clocking the DCO.
The minimum multiplier for the FLL, from Table 8-12 is 4. Because 4 X 10 MHz is 40MHz, which is the
operational limit of the DCO, the reference clock cannot be any faster than 10 MHz.
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.7.1
FLL Engaged External Unlocked
FEE unlocked is entered when FEE is entered and the count error (Δn) output from the subtractor is greater
than the maximum nunlock or less than the minimum nunlock, as required by the lock detector to detect the
unlock condition.
The ICG will remain in this state while the count error (Δn) is greater than the maximum nlock or less than
the minimum nlock, as required by the lock detector to detect the lock condition.
In this state, the pulse counter, subtractor, digital loop filter, and DCO form a closed loop and attempt to
lock it according to their operational descriptions later in this section. Upon entering this state and until
the FLL becomes locked, the output clock signal ICGOUT frequency is given by fICGDCLK / (2×R) This
extra divide by two prevents frequency overshoots during the initial locking process from exceeding
chip-level maximum frequency specifications. After the FLL has locked, if an unexpected loss of lock
causes it to re-enter the unlocked state while the ICG remains in FEE mode, the output clock signal
ICGOUT frequency is given by fICGDCLK / R.
8.4.7.2
FLL Engaged External Locked
FEE locked is entered from FEE unlocked when the count error (Δn) is less than nlock (max) and greater
than nlock (min) for a given number of samples, as required by the lock detector to detect the lock
condition. The output clock signal ICGOUT frequency is given by fICGDCLK/R. In FLL engaged external
locked, the filter value is updated only once every four comparison cycles. The update made is an average
of the error measurements taken in the four previous comparisons.
8.4.8
FLL Lock and Loss-of-Lock Detection
To determine the FLL locked and loss-of-lock conditions, the pulse counter counts the pulses of the DCO
for one comparison cycle (see Table 8-9 for explanation of a comparison cycle) and passes this number to
the subtractor. The subtractor compares this value to the value in MFD and produces a count error, Δn. To
achieve locked status, Δn must be between nlock (min) and nlock (max). After the FLL has locked, Δn must
stay between nunlock (min) and nunlock (max) to remain locked. If Δn goes outside this range unexpectedly,
the LOLS status bit is set and remains set until cleared by software or until the MCU is reset. LOLS is
cleared by reading ICGS1 then writing 1 to ICGIF (LOLRE = 0), or by a loss-of-lock induced reset
(LOLRE = 1), or by any MCU reset.
If the ICG enters the off state due to stop mode when ENBDM = OSCSTEN = 0, the FLL loses locked
status (LOCK is cleared), but LOLS remains unchanged because this is not an unexpected loss-of-lock
condition. Though it would be unusual, if ENBDM is cleared to 0 while the MCU is in stop, the ICG enters
the off state. Because this is an unexpected stopping of clocks, LOLS will be set when the MCU wakes up
from stop.
Expected loss of lock occurs when the MFD or CLKS bits are changed or in FEI mode only, when the
TRIM bits are changed. In these cases, the LOCK bit will be cleared until the FLL regains lock, but the
LOLS will not be set.
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.9
FLL Loss-of-Clock Detection
The reference clock and the DCO clock are monitored under different conditions (see Table 8-8). Provided
the reference frequency is being monitored, ERCS = 1 indicates that the reference clock meets minimum
frequency requirements. When the reference and/or DCO clock(s) are being monitored, if either one falls
below a certain frequency, fLOR and fLOD, respectively, the LOCS status bit will be set to indicate the error.
LOCS will remain set until it is acknowledged or until the MCU is reset. LOCS is cleared by reading
ICGS1 then writing 1 to ICGIF (LOCRE = 0), or by a loss-of-clock induced reset (LOCRE = 1), or by any
MCU reset.
If the ICG is in FEE, a loss of reference clock causes the ICG to enter SCM, and a loss of DCO clock causes
the ICG to enter FBE mode. If the ICG is in FBE mode, a loss of reference clock will cause the ICG to
enter SCM. In each case, the CLKST and CLKS bits will be automatically changed to reflect the new state.
If the ICG is in FEE mode when a loss of clock occurs and the ERCS is still set to 1, then the CLKST bits
are set to 10 and the ICG reverts to FBE mode.
A loss of clock will also cause a loss of lock when in FEE or FEI modes. Because the method of clearing
the LOCS and LOLS bits is the same, this would only be an issue in the unlikely case that LOLRE = 1 and
LOCRE = 0. In this case, the interrupt would be overridden by the reset for the loss of lock.
Table 8-8. Clock Monitoring (When LOCD = 0)
Mode
CLKS
REFST
ERCS
External Reference
Clock
Monitored?
DCO Clock
Monitored?
Off
0X or 11
X
Forced Low
No
No
SCM
(CLKST = 00)
FEI
(CLKST = 01)
FBE
(CLKST = 10)
FEE
(CLKST = 11)
1
2
10
0
Forced Low
No
No
10
1
Real-Time1
Yes(1)
No
0X
X
Forced Low
No
Yes2
10
0
Forced High
No
Yes(2)
10
1
Real-Time
Yes
Yes(2)
11
X
Real-Time
Yes
Yes(2)
0X
X
Forced Low
No
Yes
11
X
Real-Time
Yes
Yes
10
0
Forced High
No
No
10
1
Real-Time
Yes
No
11
X
Real-Time
Yes
Yes
If ENABLE is high (waiting for external crystal start-up after exiting stop).
DCO clock will not be monitored until DCOS = 1 upon entering SCM from off or FLL bypassed external mode.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.10
Clock Mode Requirements
A clock mode is requested by writing to CLKS1:CLKS0 and the actual clock mode is indicated by
CLKST1:CLKST0. Provided minimum conditions are met, the status shown in CLKST1:CLKST0 should
be the same as the requested mode in CLKS1:CLKS0. Table 8-9 shows the relationship between CLKS,
CLKST, and ICGOUT. It also shows the conditions for CLKS = CLKST or the reason CLKS ≠ CLKST.
NOTE
If a crystal will be used before the next reset, then be sure to set REFS = 1
and CLKS = 1x on the first write to the ICGC1 register. Failure to do so will
result in “locking” REFS = 0 which will prevent the oscillator amplifier
from being enabled until the next reset occurs.
Table 8-9. ICG State Table
Actual
Mode
(CLKST)
Off
(XX)
SCM
(00)
FEI
(01)
FBE
(10)
FEE
(11)
Desired
Mode
(CLKS)
Range
Reference
Frequency
(fREFERENCE)
Comparison
Cycle Time
ICGOUT
Conditions1 for
CLKS = CLKST
Reason
CLKS1 ≠
CLKST
Off
(XX)
X
0
—
0
—
—
FBE
(10)
X
0
—
0
—
ERCS = 0
SCM
(00)
X
fICGIRCLK/72
8/fICGIRCLK
ICGDCLK/R
Not switching
from FBE to
SCM
—
FEI
(01)
0
fICGIRCLK/7(1)
8/fICGIRCLK
ICGDCLK/R
—
DCOS = 0
FBE
(10)
X
fICGIRCLK/7(1)
8/fICGIRCLK
ICGDCLK/R
—
ERCS = 0
FEE
(11)
X
fICGIRCLK/7(1)
8/fICGIRCLK
ICGDCLK/R
—
DCOS = 0 or
ERCS = 0
FEI
(01)
0
fICGIRCLK/7
8/fICGIRCLK
ICGDCLK/R
DCOS = 1
—
FEE
(11)
X
fICGIRCLK/7
8/fICGIRCLK
ICGDCLK/R
—
ERCS = 0
FBE
(10)
X
0
—
ICGERCLK/R
ERCS = 1
—
FEE
(11)
X
0
—
ICGERCLK/R
—
LOCS = 1 &
ERCS = 1
0
fICGERCLK
2/fICGERCLK
ICGDCLK/R3
ERCS = 1 and
DCOS = 1
—
1
fICGERCLK
128/fICGERCLK
ICGDCLK/R(2)
ERCS = 1 and
DCOS = 1
—
FEE
(11)
1
CLKST will not update immediately after a write to CLKS. Several bus cycles are required before CLKST updates to the new
value.
2
The reference frequency has no effect on ICGOUT in SCM, but the reference frequency is still used in making the comparisons
that determine the DCOS bit
3 After initial LOCK; will be ICGDCLK/2R during initial locking process and while FLL is re-locking after the MFD bits are changed.
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Chapter 8 Internal Clock Generator (S08ICGV4)
8.4.11
Fixed Frequency Clock
The ICG provides a fixed frequency clock output, XCLK, for use by on-chip peripherals. This output is
equal to the internal bus clock, BUSCLK, in all modes except FEE. In FEE mode, XCLK is equal to
ICGERCLK ÷ 2 when the following conditions are met:
• (P × N) ÷ R ≥ 4 where P is determined by RANGE (see Table 8-11), N and R are determined by
MFD and RFD respectively (see Table 8-12).
• LOCK = 1.
If the above conditions are not true, then XCLK is equal to BUSCLK.
When the ICG is in either FEI or SCM mode, XCLK is turned off. Any peripherals which can use XCLK
as a clock source must not do so when the ICG is in FEI or SCM mode.
8.4.12
High Gain Oscillator
The oscillator has the option of running in a high gain oscillator (HGO) mode, which improves the
oscillator's resistance to EMC noise when running in FBE or FEE modes. This option is selected by writing
a 1 to the HGO bit in the ICGC1 register. HGO is used with both the high and low range oscillators but is
only valid when REFS = 1 in the ICGC1 register. When HGO = 0, the standard low-power oscillator is
selected. This bit is writable only once after any reset.
8.5
8.5.1
Initialization/Application Information
Introduction
The section is intended to give some basic direction on which configuration a user would want to select
when initializing the ICG. For some applications, the serial communication link may dictate the accuracy
of the clock reference. For other applications, lowest power consumption may be the chief clock
consideration. Still others may have lowest cost as the primary goal. The ICG allows great flexibility in
choosing which is best for any application.
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Chapter 8 Internal Clock Generator (S08ICGV4)
Table 8-10. ICG Configuration Consideration
Clock Reference Source = Internal
1
Clock Reference Source = External
FLL
Engaged
FEI
4 MHz < fBus < 20 MHz.
Medium power (will be less than FEE if oscillator
range = high)
Good clock accuracy (After IRG is trimmed)
Lowest system cost (no external components
required)
IRG is on. DCO is on. 1
FEE
4 MHz < fBus < 20 MHz
Medium power (will be less than FEI if oscillator
range = low)
High clock accuracy
Medium/High system cost (crystal, resonator or
external clock source required)
IRG is off. DCO is on.
FLL
Bypassed
SCM
This mode is mainly provided for quick and reliable
system startup.
3 MHz < fBus < 5 MHz (default).
3 MHz < fBus < 20 MHz (via filter bits).
Medium power
Poor accuracy.
IRG is off. DCO is on and open loop.
FBE
fBus range ≤ 8 MHz when crystal or resonator is
used.
Lowest power
Highest clock accuracy
Medium/High system cost (Crystal, resonator or
external clock source required)
IRG is off. DCO is off.
The IRG typically consumes 100 μA. The FLL and DCO typically consumes 0.5 to 2.5 mA, depending upon output frequency.
For minimum power consumption and minimum jitter, choose N and R to be as small as possible.
The following sections contain initialization examples for various configurations.
NOTE
Hexadecimal values designated by a preceding $, binary values designated
by a preceding %, and decimal values have no preceding character.
Important configuration information is repeated here for reference.
Table 8-11. ICGOUT Frequency Calculation Options
Clock Scheme
SCM — self-clocked mode (FLL bypassed
internal)
FBE — FLL bypassed external
FEI — FLL engaged internal
FEE — FLL engaged external
1
fICGOUT1
P
Note
fICGDCLK / R
NA
Typical fICGOUT = 8 MHz
immediately after reset
fext / R
NA
(fIRG / 7)* 64 * N / R
64
fext * P * N / R
Range = 0 ; P = 64
Range = 1; P = 1
Typical fIRG = 243 kHz
Ensure that fICGDCLK, which is equal to fICGOUT * R, does not exceed fICGDCLKmax.
Table 8-12. MFD and RFD Decode Table
MFD Value
Multiplication Factor (N)
RFD
Division Factor (R)
000
001
010
011
100
4
6
8
10
12
000
001
010
011
100
÷1
÷2
÷4
÷8
÷16
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Chapter 8 Internal Clock Generator (S08ICGV4)
Table 8-12. MFD and RFD Decode Table
101
110
111
8.5.2
14
16
18
101
110
111
÷32
÷64
÷128
Example #1: External Crystal = 32 kHz, Bus Frequency = 4.19 MHz
In this example, the FLL will be used (in FEE mode) to multiply the external 32 kHz oscillator up to
8.38 MHz to achieve 4.19 MHz bus frequency.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT, which corresponds to a 4 MHz bus frequency (fBus).
The clock scheme will be FLL engaged, external (FEE). So
fICGOUT = fext * P * N / R ; P = 64, fext = 32 kHz
Eqn. 8-1
N / R = 8.38 MHz /(32 kHz * 64) = 4 ; we can choose N = 4 and R =1
Eqn. 8-2
Solving for N / R gives:
The values needed in each register to set up the desired operation are:
ICGC1 = $38 (%00111000)
Bit 7
Bit 6
Bit 5
Bits 4:3
Bit 2
Bit 1
Bit 0
HGO
RANGE
REFS
CLKS
OSCSTEN
LOCD
0
0
1
11
0
0
0
Configures oscillator for low power
Configures oscillator for low-frequency range; FLL prescale factor is 64
Oscillator using crystal or resonator is requested
FLL engaged, external reference clock mode
Oscillator disabled
Loss-of-clock detection enabled
Unimplemented or reserved, always reads zero
ICGC2 = $00 (%00000000)
Bit 7
Bits 6:4
Bit 3
Bits 2:0
LOLRE
MFD
LOCRE
RFD
0
Generates an interrupt request on loss of lock
000 Sets the MFD multiplication factor to 4
0
Generates an interrupt request on loss of clock
000 Sets the RFD division factor to ÷1
ICGS1 = $xx
This is read only except for clearing interrupt flag
ICGS2 = $xx
This is read only; should read DCOS = 1 before performing any time critical tasks
ICGFLTLU/L = $xx
Only needed in self-clocked mode; FLT will be adjusted by loop to give 8.38 MHz DCO clock
Bits 15:12 unused
0000
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
151
Chapter 8 Internal Clock Generator (S08ICGV4)
Bits 11:0 FLT
No need for user initialization
ICGTRM = $xx
Bits 7:0
TRIM
Only need to write when trimming internal oscillator; not used when external
crystal is clock source
Figure 8-14 shows flow charts for three conditions requiring ICG initialization.
RESET
INITIALIZE ICG
ICGC1 = $38
ICGC2 = $00
CHECK
FLL LOCK STATUS.
LOCK = 1?
QUICK RECOVERY FROM STOP
MINIMUM CURRENT DRAW IN STOP
RECOVERY FROM STOP
OSCSTEN = 1
RECOVERY FROM STOP
OSCSTEN = 0
CHECK
FLL LOCK STATUS.
LOCK = 1?
NO
CHECK
FLL LOCK STATUS.
LOCK = 1?
NO
YES
YES
NO
CONTINUE
CONTINUE
YES
CONTINUE
NOTE: THIS WILL REQUIRE THE OSCILLATOR TO START AND
STABILIZE. ACTUAL TIME IS DEPENDENT ON CRYSTAL /RESONATOR
AND EXTERNAL CIRCUITRY.
Figure 8-14. ICG Initialization for FEE in Example #1
MC9S08AC16 Series Data Sheet, Rev. 0
152
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.5.3
Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz
In this example, the FLL will be used (in FEE mode) to multiply the external 4 MHz oscillator up to
40-MHz to achieve 20 MHz bus frequency.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT which corresponds to a 4 MHz bus frequency (fBus).
During reset initialization software, the clock scheme will be set to FLL engaged, external (FEE). So
fICGOUT = fext * P * N / R ; P = 1, fext = 4.00 MHz
Eqn. 8-3
N / R = 40 MHz /(4 MHz * 1) = 10 ; We can choose N = 10 and R = 1
Eqn. 8-4
Solving for N / R gives:
The values needed in each register to set up the desired operation are:
ICGC1 = $78
Bit 7
Bit 6
Bit 5
Bits 4:3
Bit 2
Bit 1
Bit 0
HGO
RANGE
REFS
CLKS
OSCSTEN
LOCD
ICGC2 = $30
Bit 7
Bit 6:4
Bit 3
Bit 2:0
(%01111000)
0
1
1
11
0
0
0
Configures oscillator for low power
Configures oscillator for high-frequency range; FLL prescale factor is 1
Requests an oscillator
FLL engaged, external reference clock mode
Disables the oscillator
Loss-of-clock detection enabled
Unimplemented or reserved, always reads zero
(%00110000)
LOLRE
MFD
LOCRE
RFD
0
Generates an interrupt request on loss of lock
011 Sets the MFD multiplication factor to 10
0
Generates an interrupt request on loss of clock
000 Sets the RFD division factor to ÷1
ICGS1 = $xx
This is read only except for clearing interrupt flag
ICGS2 = $xx
This is read only. Should read DCOS before performing any time critical tasks
ICGFLTLU/L = $xx
Not used in this example
ICGTRM
Not used in this example
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
153
Chapter 8 Internal Clock Generator (S08ICGV4)
RECOVERY
FROM STOP
RESET
INITIALIZE ICG
ICGC1 = $7A
ICGC2 = $30
CHECK
FLL LOCK STATUS
LOCK = 1?
SERVICE INTERRUPT
SOURCE (fBus = 4 MHz)
NO
YES
CHECK
FLL LOCK STATUS
LOCK = 1?
NO
YES
CONTINUE
CONTINUE
Figure 8-15. ICG Initialization and Stop Recovery for Example #2
MC9S08AC16 Series Data Sheet, Rev. 0
154
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.5.4
Example #3: No External Crystal Connection, 5.4 MHz Bus
Frequency
In this example, the FLL will be used (in FEI mode) to multiply the internal 243 kHz (approximate)
reference clock up to 10.8 MHz to achieve 5.4 MHz bus frequency. This system will also use the trim
function to fine tune the frequency based on an external reference signal.
After the MCU is released from reset, the ICG is in self-clocked mode (SCM) and supplies approximately
8 MHz on ICGOUT which corresponds to a 4 MHz bus frequency (fBus).
The clock scheme will be FLL engaged, internal (FEI). So
fICGOUT = (fIRG / 7) * P * N / R ; P = 64, fIRG = 243 kHz
Eqn. 8-5
Solving for N / R gives:
N / R = 10.8 MHz /(243/7 kHz * 64) = 4.86 ; We can choose N = 10 and R = 2.
Eqn. 8-6
A trim procedure will be required to hone the frequency to exactly 5.4 MHz. An example of the trim
procedure is shown in example #4.
The values needed in each register to set up the desired operation are:
ICGC1 = $28 (%00101000)
Bit 7
HGO
0
Bit 6
RANGE
0
Bit 5
REFS
1
Bits 4:3 CLKS
01
Bit 2
OSCSTEN 0
Bit 1
LOCD
0
Bit 0
0
Configures oscillator for low power
Configures oscillator for low-frequency range; FLL prescale factor is 64
Oscillator using crystal or resonator requested (bit is really a don’t care)
FLL engaged, internal reference clock mode
Disables the oscillator
Loss-of-clock enabled
Unimplemented or reserved, always reads zero
ICGC2 = $31 (%00110001)
Bit 7
LOLRE
0
Generates an interrupt request on loss of lock
Bit 6:4 MFD
011 Sets the MFD multiplication factor to 10
Bit 3
LOCRE
0
Generates an interrupt request on loss of clock
Bit 2:0 RFD
001 Sets the RFD division factor to ÷2
ICGS1 = $xx
This is read only except for clearing interrupt flag
ICGS2 = $xx
This is read only; good idea to read this before performing time critical operations
ICGFLTLU/L = $xx
Not used in this example
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
155
Chapter 8 Internal Clock Generator (S08ICGV4)
ICGTRM = $xx
Bit 7:0 TRIM
Only need to write when trimming internal oscillator; done in separate
operation (see example #4)
RECOVERY
FROM STOP
RESET
INITIALIZE ICG
ICGC1 = $28
ICGC2 = $31
CHECK
FLL LOCK STATUS.
LOCK = 1?
CHECK
FLL LOCK STATUS.
LOCK = 1?
NO
YES
NO
CONTINUE
YES
CONTINUE
NOTE: THIS WILL REQUIRE THE INTERAL REFERENCE CLOCK TO START AND
STABILIZE.
Figure 8-16. ICG Initialization and Stop Recovery for Example #3
MC9S08AC16 Series Data Sheet, Rev. 0
156
PRELIMINARY
Freescale Semiconductor
Chapter 8 Internal Clock Generator (S08ICGV4)
8.5.5
Example #4: Internal Clock Generator Trim
The internally generated clock source is guaranteed to have a period ± 25% of the nominal value. In some
cases, this may be sufficient accuracy. For other applications that require a tight frequency tolerance, a
trimming procedure is provided that will allow a very accurate source. This section outlines one example
of trimming the internal oscillator. Many other possible trimming procedures are valid and can be used.
Initial conditions:
1) Clock supplied from ATE has 500 μsec duty period
2) ICG configured for internal reference with 4 MHz bus
START TRIM PROCEDURE
ICGTRM = $80, n = 1
MEASURE
INCOMING CLOCK WIDTH
(COUNT = # OF BUS CLOCKS / 4)
COUNT < EXPECTED = 500
(RUNNING TOO SLOW)
.
CASE STATEMENT
COUNT = EXPECTED = 500
COUNT > EXPECTED = 500
(RUNNING TOO FAST)
ICGTRM =
ICGTRM - 128 / (2**n)
(DECREASING ICGTRM
INCREASES THE FREQUENCY)
ICGTRM =
ICGTRM + 128 / (2**n)
(INCREASING ICGTRM
DECREASES THE FREQUENCY)
STORE ICGTRM VALUE
IN NON-VOLATILE
MEMORY
CONTINUE
n = n+1
YES
IS n > 8?
NO
Figure 8-17. Trim Procedure
In this particular case, the MCU has been attached to a PCB and the entire assembly is undergoing final
test with automated test equipment. A separate signal or message is provided to the MCU operating under
user provided software control. The MCU initiates a trim procedure as outlined in Figure 8-17 while the
tester supplies a precision reference signal.
If the intended bus frequency is near the maximum allowed for the device, it is recommended to trim using
a reduction divisor (R) twice the final value. After the trim procedure is complete, the reduction divisor
can be restored. This will prevent accidental overshoot of the maximum clock frequency.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
157
Chapter 8 Internal Clock Generator (S08ICGV4)
MC9S08AC16 Series Data Sheet, Rev. 0
158
PRELIMINARY
Freescale Semiconductor
Chapter 9
Keyboard Interrupt (S08KBIV1)
9.1
Introduction
The MC9S08AC16 Series has one KBI module with seven keyboard interrupt inputs that are shared with
port D and port G pins. See Chapter 2, “Pins and Connections,” for more information about the logic and
hardware aspects of these pins.
9.2
Keyboard Pin Sharing
The KBI input KBIP6 shares a common pin with PTD3 and AD11, and KBI input KBIP5 shares a common
pin with PTD2 and AD10. The sharing of each of these inputs with port and ADC functions operates in
the same way as described above for KBIP7.
The KBI inputs KBIP4 – KBIP0 are shared on common pins with PTG4 – PTG0. These pins all operate
in the same way as described above for KBIP7 except that none are shared with an ADC input.
KBIP3 – KBIP0 are always falling-edge/low-level sensitive. KBIP7 – KBIP4 can be configured for
rising-edge/high-level or for falling-edge/low-level sensitivity. When any of the inputs KBIP7 – KBIP0 are
enabled and configured to detect rising edges/high levels, and the pin pullup is enabled through the
corresponding port pullup enable bit for that pin, a pulldown resistor rather than a pullup resistor is enabled
on the pin.
9.3
Features
The keyboard interrupt (KBI) module features include:
• Four falling edge/low level sensitive
• Four falling edge/low level or rising edge/high level sensitive
• Choice of edge-only or edge-and-level sensitivity
• Common interrupt flag and interrupt enable control
• Capable of waking up the MCU from stop3, stop2, stop1, or wait mode
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
159
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 9 Keyboard Interrupt (S08KBIV1)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 9-1. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
160
PRELIMINARY
Freescale Semiconductor
Chapter 9 Keyboard Interrupt (S08KBIV1)
9.3.1
KBI Block Diagram
Figure 9-2 shows the block diagram for a KBI module.
KBIP0
KBIPE0
VDD
KBIPE3
0
RESET
SYNCHRONIZER
CK
S
KBIPE4
KEYBOARD
INTERRUPT FF
KBEDG4
0
STOP
STOP BYPASS
KEYBOARD
INTERRUPT
REQUEST
KBIMOD
1
KBIPn
KBF
D CLR Q
1
KBIP4
BUSCLK
KBACK
KBIP3
KBIE
S
KBIPEn
KBEDGn
Figure 9-2. KBI Block Diagram
9.4
Register Definition
This section provides information about all registers and control bits associated with the KBI module.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all KBI registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
161
Chapter 9 Keyboard Interrupt (S08KBIV1)
9.4.1
KBI Status and Control Register (KBISC)
7
6
5
4
KBEDG7
KBEDG6
KBEDG5
KBEDG4
R
3
2
KBF
0
W
Reset
1
0
KBIE
KBIMOD
0
0
KBACK
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-3. KBI Status and Control Register (KBISC)
Table 9-1. KBISC Register Field Descriptions
Field
Description
7:4
Keyboard Edge Select for KBI Port Bits — Each of these read/write bits selects the polarity of the edges and/or
KBEDG[7:4] levels that are recognized as trigger events on the corresponding KBI port pin when it is configured as a keyboard
interrupt input (KBIPEn = 1). Also see the KBIMOD control bit, which determines whether the pin is sensitive to
edges-only or edges and levels.
0 Falling edges/low levels
1 Rising edges/high levels
3
KBF
Keyboard Interrupt Flag — This read-only status flag is set whenever the selected edge event has been
detected on any of the enabled KBI port pins. This flag is cleared by writing a 1 to the KBACK control bit. The
flag will remain set if KBIMOD = 1 to select edge-and-level operation and any enabled KBI port pin remains at
the asserted level.
KBF can be used as a software pollable flag (KBIE = 0) or it can generate a hardware interrupt request to the
CPU (KBIE = 1).
0 No KBI interrupt pending
1 KBI interrupt pending
2
KBACK
Keyboard Interrupt Acknowledge — This write-only bit (reads always return 0) is used to clear the KBF status
flag by writing a 1 to KBACK. When KBIMOD = 1 to select edge-and-level operation and any enabled KBI port
pin remains at the asserted level, KBF is being continuously set so writing 1 to KBACK does not clear the KBF
flag.
1
KBIE
Keyboard Interrupt Enable — This read/write control bit determines whether hardware interrupts are generated
when the KBF status flag equals 1. When KBIE = 0, no hardware interrupts are generated, but KBF can still be
used for software polling.
0 KBF does not generate hardware interrupts (use polling)
1 KBI hardware interrupt requested when KBF = 1
KBIMOD
Keyboard Detection Mode — This read/write control bit selects either edge-only detection or edge-and-level
detection. KBI port bits 3 through 0 can detect falling edges-only or falling edges and low levels. KBI port bits 7
through 4 can be configured to detect either:
• Rising edges-only or rising edges and high levels (KBEDGn = 1)
• Falling edges-only or falling edges and low levels (KBEDGn = 0)
0 Edge-only detection
1 Edge-and-level detection
MC9S08AC16 Series Data Sheet, Rev. 0
162
PRELIMINARY
Freescale Semiconductor
Chapter 9 Keyboard Interrupt (S08KBIV1)
9.4.2
KBI Pin Enable Register (KBIPE)
7
6
5
4
3
2
1
0
KBIPE7
KBIPE6
KBIPE5
KBIPE4
KBIPE3
KBIPE2
KBIPE1
KBIPE0
0
0
0
0
0
0
0
0
R
W
Reset
= Unimplemented or Reserved
Figure 9-4. KBI Pin Enable Register (KBIPE)
Table 9-2. KBIPE Register Field Descriptions
Field
Description
7:0
KBIPE[7:0]
9.5
9.5.1
Keyboard Pin Enable for KBI Port Bits — Each of these read/write bits selects whether the associated KBI
port pin is enabled as a keyboard interrupt input or functions as a general-purpose I/O pin.
0 Bit n of KBI port is a general-purpose I/O pin not associated with the KBI
1 Bit n of KBI port enabled as a keyboard interrupt input
Functional Description
Pin Enables
The KBIPEn control bits in the KBIPE register allow a user to enable (KBIPEn = 1) any combination of
KBI-related port pins to be connected to the KBI module. Pins corresponding to 0s in KBIPE are
general-purpose I/O pins that are not associated with the KBI module.
9.5.2
Edge and Level Sensitivity
Synchronous logic is used to detect edges. Prior to detecting an edge, enabled keyboard inputs in a KBI
module must be at the deasserted logic level.
A falling edge is detected when an enabled keyboard input signal is seen as a logic 1 (the deasserted level)
during one bus cycle and then a logic 0 (the asserted level) during the next cycle.
A rising edge is detected when the input signal is seen as a logic 0 during one bus cycle and then a logic 1
during the next cycle.
The KBIMOD control bit can be set to reconfigure the detection logic so that it detects edges and levels.
In KBIMOD = 1 mode, the KBF status flag becomes set when an edge is detected (when one or more
enabled pins change from the deasserted to the asserted level while all other enabled pins remain at their
deasserted levels), but the flag is continuously set (and cannot be cleared) as long as any enabled keyboard
input pin remains at the asserted level. When the MCU enters stop mode, the synchronous edge-detection
logic is bypassed (because clocks are stopped). In stop mode, KBI inputs act as asynchronous
level-sensitive inputs so they can wake the MCU from stop mode.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
163
Chapter 9 Keyboard Interrupt (S08KBIV1)
9.5.3
KBI Interrupt Controls
The KBF status flag becomes set (1) when an edge event has been detected on any KBI input pin. If
KBIE = 1 in the KBISC register, a hardware interrupt will be requested whenever KBF = 1. The KBF flag
is cleared by writing a 1 to the keyboard acknowledge (KBACK) bit.
When KBIMOD = 0 (selecting edge-only operation), KBF is always cleared by writing 1 to KBACK.
When KBIMOD = 1 (selecting edge-and-level operation), KBF cannot be cleared as long as any keyboard
input is at its asserted level.
MC9S08AC16 Series Data Sheet, Rev. 0
164
PRELIMINARY
Freescale Semiconductor
Chapter 10
Timer/PWM (S08TPMV3)
10.1
Introduction
The MC9S08AC16 Series includes three independent timer/PWM (TPM) modules which support
traditional input capture, output compare, or buffered edge-aligned pulse-width modulation (PWM) on
each channel. A control bit in each TPM configures all channels in that timer to operate as center-aligned
PWM functions. In each TPM, timing functions are based on a separate 16-bit counter with prescaler and
modulo features to control frequency and range (period between overflows) of the time reference. This
timing system is ideally suited for a wide range of control applications, and the center-aligned PWM
capability on the TPM extends the field of applications to motor control in small appliances.
The use of the fixed system clock, XCLK, as the clock source for any of the TPM modules allows the TPM
prescaler to run using the oscillator rate divided by two (ICGERCLK/2). This option is only available if
the ICG is configured in FEE mode and the proper conditions are met (see Section 8.4.11, “Fixed
Frequency Clock”). In all other ICG modes this selection is redundant because XCLK is the same as
BUSCLK.
An external clock source can be connected to the TPMCLK pin. The maximum frequency for TPMCLK
is the bus clock frequency divided by 4. All three TPM modules can independently select TPMCLK as the
clock source.
NOTE
The S9S08AW16A and the S9S08AW8A devices do not implement TPM3.
These devices only have the 2-channel TPM1 and the 2-channel TPM2 on
44-and 48=pin packages. These devices only have 2-channel TPM1 and
2-channel TPM2 on 32-pin packages.
10.2
Features
The timer system in the MC9S08AC16 Series includes a 4-channel TPM1 (2-channel TPM1 on 32-bit
package option), a separate 2-channel TPM2 and a separate 2-channel TPM3. Timer system features
include:
• A total of up to eight channels:
— Each channel may be input capture, output compare, or buffered edge-aligned PWM
— Rising-edge, falling-edge, or any-edge input capture trigger
— Set, clear, or toggle output compare action
— Selectable polarity on PWM outputs
• Each TPM may be configured for buffered, center-aligned pulse-width modulation (CPWM) on all
channels
• Clock source to prescaler for each TPM is independently selectable as bus clock, fixed system
clock, or an external pin:
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
165
Chapter 10 Timer/PWM (S08TPMV3)
•
•
•
•
— Prescale taps for divide by 1, 2, 4, 8, 16, 32, 64, or 128
— External clock input: TPMCLK for use by TPM1, TPM2, and/or TPM3
16-bit free-running or up/down (CPWM) count operation
16-bit modulus register to control counter range
Timer system enable
One interrupt per channel plus a terminal count interrupt for each TPM module
MC9S08AC16 Series Data Sheet, Rev. 0
166
PRELIMINARY
Freescale Semiconductor
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 10 Timer/PWM (S08TPMV3)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 10-1. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
167
Chapter 10 Timer/PWM (S08TPMV3)
10.3
TPMV3 Differences from Previous Versions
The TPMV3 is the latest version of the Timer/PWM module that addresses errata found in previous
versions. The following section outlines the differences between TPMV3 and TPMV2 modules, and any
considerations that should be taken when porting code.
Table 10-1. TPMV2 and TPMV3 Porting Considerations
Action
TPMV3
TPMV2
Write to TPMxCnTH:L registers1
Any write to TPMxCNTH or TPMxCNTL registers
Clears the TPM counter
(TPMxCNTH:L) and the
prescaler counter.
Clears the TPM counter
(TPMxCNTH:L) only.
Read of TPMxCNTH:L registers1
In BDM mode, any read of TPMxCNTH:L registers
Returns the value of the TPM If only one byte of the
counter that is frozen.
TPMxCNTH:L registers was
read before the BDM mode
became active, returns the
latched value of TPMxCNTH:L
from the read buffer (instead of
the frozen TPM counter value).
In BDM mode, a write to TPMxSC, TPMxCNTH or TPMxCNTL Clears this read coherency
mechanism.
Does not clear this read
coherency mechanism.
Read of TPMxCnVH:L registers2
In BDM mode, any read of TPMxCnVH:L registers
Returns the value of the
TPMxCnVH:L register.
If only one byte of the
TPMxCnVH:L registers was
read before the BDM mode
became active, returns the
latched value of TPMxCNTH:L
from the read buffer (instead of
the value in the TPMxCnVH:L
registers).
In BDM mode, a write to TPMxCnSC
Clears this read coherency
mechanism.
Does not clear this read
coherency mechanism.
In Input Capture mode, writes to TPMxCnVH:L registers3
Not allowed.
Allowed.
In Output Compare mode, when (CLKSB:CLKSA not = 0:0),
writes to TPMxCnVH:L registers3
Update the TPMxCnVH:L
registers with the value of
their write buffer at the next
change of the TPM counter
(end of the prescaler
counting) after the second
byte is written.
Always update these registers
when their second byte is
written.
Write to TPMxCnVH:L registers
MC9S08AC16 Series Data Sheet, Rev. 0
168
PRELIMINARY
Freescale Semiconductor
Chapter 10 Timer/PWM (S08TPMV3)
Table 10-1. TPMV2 and TPMV3 Porting Considerations (continued)
Action
TPMV3
TPMV2
In Edge-Aligned PWM mode when (CLKSB:CLKSA not = 00), Update the TPMxCnVH:L
writes to TPMxCnVH:L registers
registers with the value of
their write buffer after both
bytes were written and when
the TPM counter changes
from (TPMxMODH:L - 1) to
(TPMxMODH:L).
Note: If the TPM counter is a
free-running counter, then
this update is made when the
TPM counter changes from
$FFFE to $FFFF.
Update after both bytes are
written and when the TPM
counter changes from
TPMxMODH:L to $0000.
In Center-Aligned PWM mode when (CLKSB:CLKSA not =
00), writes to TPMxCnVH:L registers4
Update the TPMxCnVH:L
registers with the value of
their write buffer after both
bytes are written and when
the TPM counter changes
from (TPMxMODH:L - 1) to
(TPMxMODH:L).
Note: If the TPM counter is a
free-running counter, then
this update is made when the
TPM counter changes from
$FFFE to $FFFF.
Update after both bytes are
written and when the TPM
counter changes from
TPMxMODH:L to
(TPMxMODH:L - 1).
Produces 100% duty cycle.
Produces 0% duty cycle.
Produces a near 100% duty
cycle.
Produces 0% duty cycle.
TPMxCnVH:L is changed from 0x0000 to a non-zero value7
Waits for the start of a new
PWM period to begin using
the new duty cycle setting.
Changes the channel output at
the middle of the current PWM
period (when the count
reaches 0x0000).
TPMxCnVH:L is changed from a non-zero value to 0x00008
Finishes the current PWM
period using the old duty
cycle setting.
Finishes the current PWM
period using the new duty cycle
setting.
Center-Aligned PWM
When TPMxCnVH:L = TPMxMODH:L5
When TPMxCnVH:L = (TPMxMODH:L -
1)6
Write to TPMxMODH:L registers in BDM mode
In BDM mode, a write to TPMxSC register
1
2
3
4
5
6
7
Clears the write coherency
Does not clear the write
mechanism of TPMxMODH:L coherency mechanism.
registers.
For more information, refer to Section 10.5.2, “TPM-Counter Registers (TPMxCNTH:TPMxCNTL).” [SE110-TPM case 7]
For more information, refer to Section 10.5.5, “TPM Channel Value Registers (TPMxCnVH:TPMxCnVL).”
For more information, refer to Section 10.6.2.1, “Input Capture Mode.”
For more information, refer to Section 10.6.2.4, “Center-Aligned PWM Mode.”
For more information, refer to Section 10.6.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 1]
For more information, refer to Section 10.6.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 2]
For more information, refer to Section 10.6.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 3 and 5]
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
169
Chapter 10 Timer/PWM (S08TPMV3)
8
For more information, refer to Section 10.6.2.4, “Center-Aligned PWM Mode.” [SE110-TPM case 4]
10.3.1
Migrating from TPMV1
In addition to Section 10.3, “TPMV3 Differences from Previous Versions,” keep in mind the following
considerations when migrating from a device that uses TPMV1.
• You can write to the Channel Value register (TPMxCnV) when the timer is not in input capture
mode for TPMV2, not TPMV3.
• In edge- or center- aligned modes, the Channel Value register (TPMxCnV) registers only update
when the timer changes from TPMMOD-1 to TPMMOD, or in the case of a free running timer
from 0xFFFE to 0xFFFF.
• Also, when configuring the TPM modules, it is best to write to TPMxSC before TPMxCnV as a
write to TPMxSC resets the coherency mechanism on the TPMxCnV registers.
Table 10-2. Migrating to TPMV3 Considerations
When...
Action / Best Practice
Writing to the Channel Value Register (TPMxCnV)
register...
Timer must be in Input Capture mode.
Updating the Channel Value Register (TPMxCnV) Only occurs when the timer changes from
register in edge-aligned or center-aligned modes... TPMMOD-1 to TPMMOD (or in the case of a free
running timer, from 0xFFFE to 0xFFFF).
Reseting the coherency mechanism for the
Channel Value Register (TPMxCnV) register...
Write to TPMxSC.
Configuring the TPM modules...
Write first to TPMxSC and then to TPMxCnV
register.
MC9S08AC16 Series Data Sheet, Rev. 0
170
PRELIMINARY
Freescale Semiconductor
Chapter 10 Timer/PWM Module (S08TPMV3)
10.3.2
Features
The TPM includes these distinctive features:
• One to eight channels:
— Each channel may be input capture, output compare, or edge-aligned PWM
— Rising-Edge, falling-edge, or any-edge input capture trigger
— Set, clear, or toggle output compare action
— Selectable polarity on PWM outputs
• Module may be configured for buffered, center-aligned pulse-width-modulation (CPWM) on all
channels
• Timer clock source selectable as prescaled bus clock, fixed system clock, or an external clock pin
— Prescale taps for divide-by 1, 2, 4, 8, 16, 32, 64, or 128
— Fixed system clock source are synchronized to the bus clock by an on-chip synchronization
circuit
— External clock pin may be shared with any timer channel pin or a separated input pin
• 16-bit free-running or modulo up/down count operation
• Timer system enable
• One interrupt per channel plus terminal count interrupt
10.3.3
Modes of Operation
In general, TPM channels may be independently configured to operate in input capture, output compare,
or edge-aligned PWM modes. A control bit allows the whole TPM (all channels) to switch to
center-aligned PWM mode. When center-aligned PWM mode is selected, input capture, output compare,
and edge-aligned PWM functions are not available on any channels of this TPM module.
When the microcontroller is in active BDM background or BDM foreground mode, the TPM temporarily
suspends all counting until the microcontroller returns to normal user operating mode. During stop mode,
all system clocks, including the main oscillator, are stopped; therefore, the TPM is effectively disabled
until clocks resume. During wait mode, the TPM continues to operate normally. Provided the TPM does
not need to produce a real time reference or provide the interrupt source(s) needed to wake the MCU from
wait mode, the user can save power by disabling TPM functions before entering wait mode.
• Input capture mode
When a selected edge event occurs on the associated MCU pin, the current value of the 16-bit timer
counter is captured into the channel value register and an interrupt flag bit is set. Rising edges,
falling edges, any edge, or no edge (disable channel) may be selected as the active edge which
triggers the input capture.
• Output compare mode
When the value in the timer counter register matches the channel value register, an interrupt flag
bit is set, and a selected output action is forced on the associated MCU pin. The output compare
action may be selected to force the pin to zero, force the pin to one, toggle the pin, or ignore the
pin (used for software timing functions).
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
171
Chapter 10 Timer/PWM Module (S08TPMV3)
•
•
Edge-aligned PWM mode
The value of a 16-bit modulo register plus 1 sets the period of the PWM output signal. The channel
value register sets the duty cycle of the PWM output signal. The user may also choose the polarity
of the PWM output signal. Interrupts are available at the end of the period and at the duty-cycle
transition point. This type of PWM signal is called edge-aligned because the leading edges of all
PWM signals are aligned with the beginning of the period, which is the same for all channels within
a TPM.
Center-aligned PWM mode
Twice the value of a 16-bit modulo register sets the period of the PWM output, and the
channel-value register sets the half-duty-cycle duration. The timer counter counts up until it
reaches the modulo value and then counts down until it reaches zero. As the count matches the
channel value register while counting down, the PWM output becomes active. When the count
matches the channel value register while counting up, the PWM output becomes inactive. This type
of PWM signal is called center-aligned because the centers of the active duty cycle periods for all
channels are aligned with a count value of zero. This type of PWM is required for types of motors
used in small appliances.
This is a high-level description only. Detailed descriptions of operating modes are in later sections.
10.3.4
Block Diagram
The TPM uses one input/output (I/O) pin per channel, TPMxCHn (timer channel n) where n is the channel
number (1-8). The TPM shares its I/O pins with general purpose I/O port pins (refer to I/O pin descriptions
in full-chip specification for the specific chip implementation).
Figure 10-2 shows the TPM structure. The central component of the TPM is the 16-bit counter that can
operate as a free-running counter or a modulo up/down counter. The TPM counter (when operating in
normal up-counting mode) provides the timing reference for the input capture, output compare, and
edge-aligned PWM functions. The timer counter modulo registers, TPMxMODH:TPMxMODL, control
the modulo value of the counter (the values 0x0000 or 0xFFFF effectively make the counter free running).
Software can read the counter value at any time without affecting the counting sequence. Any write to
either half of the TPMxCNT counter resets the counter, regardless of the data value written.
MC9S08AC16 Series Data Sheet, Rev. 0
172
PRELIMINARY
Freescale Semiconductor
Chapter 10 Timer/PWM Module (S08TPMV3)
BUS CLOCK
FIXED SYSTEM CLOCK
SYNC
EXTERNAL CLOCK
CLOCK SOURCE
SELECT
OFF, BUS, FIXED
SYSTEM CLOCK, EXT
PRESCALE AND SELECT
1, 2, 4, 8, 16, 32, 64,
or 128
CLKSB:CLKSA
PS2:PS1:PS0
CPWMS
16-BIT COUNTER
TOF
COUNTER RESET
TOIE
INTERRUPT
LOGIC
16-BIT COMPARATOR
TPMxMODH:TPMxMODL
CHANNEL 0
ELS0B
ELS0A
PORT
LOGIC
TPMxCH0
16-BIT COMPARATOR
TPMxC0VH:TPMxC0VL
CH0F
INTERNAL BUS
16-BIT LATCH
CHANNEL 1
MS0B
MS0A
ELS1B
ELS1A
CH0IE
INTERRUPT
LOGIC
PORT
LOGIC
TPMxCH1
16-BIT COMPARATOR
TPMxC1VH:TPMxC1VL
CH1F
16-BIT LATCH
MS1B
CH1IE
MS1A
INTERRUPT
LOGIC
Up to 8 channels
CHANNEL 7
ELS7B
ELS7A
PORT
LOGIC
TPMxCH7
16-BIT COMPARATOR
TPMxC7VH:TPMxC7VL
CH7F
16-BIT LATCH
MS7B
MS7A
CH7IE
INTERRUPT
LOGIC
Figure 10-2. TPM Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
173
Chapter 10 Timer/PWM Module (S08TPMV3)
The TPM channels are programmable independently as input capture, output compare, or edge-aligned
PWM channels. Alternately, the TPM can be configured to produce CPWM outputs on all channels. When
the TPM is configured for CPWMs, the counter operates as an up/down counter; input capture, output
compare, and EPWM functions are not practical.
If a channel is configured as input capture, an internal pullup device may be enabled for that channel. The
details of how a module interacts with pin controls depends upon the chip implementation because the I/O
pins and associated general purpose I/O controls are not part of the module. Refer to the discussion of the
I/O port logic in a full-chip specification.
Because center-aligned PWMs are usually used to drive 3-phase AC-induction motors and brushless DC
motors, they are typically used in sets of three or six channels.
10.4
Signal Description
Table 10-3 shows the user-accessible signals for the TPM. The number of channels may be varied from
one to eight. When an external clock is included, it can be shared with the same pin as any TPM channel;
however, it could be connected to a separate input pin. Refer to the I/O pin descriptions in full-chip
specification for the specific chip implementation.
Table 10-3. Signal Properties
Name
Function
EXTCLK1
2
TPMxCHn
External clock source which may be selected to drive the TPM counter.
I/O pin associated with TPM channel n
1
When preset, this signal can share any channel pin; however depending upon full-chip
implementation, this signal could be connected to a separate external pin.
2 n=channel number (1 to 8)
Refer to documentation for the full-chip for details about reset states, port connections, and whether there
is any pullup device on these pins.
TPM channel pins can be associated with general purpose I/O pins and have passive pullup devices which
can be enabled with a control bit when the TPM or general purpose I/O controls have configured the
associated pin as an input. When no TPM function is enabled to use a corresponding pin, the pin reverts
to being controlled by general purpose I/O controls, including the port-data and data-direction registers.
Immediately after reset, no TPM functions are enabled, so all associated pins revert to general purpose I/O
control.
10.4.1
Detailed Signal Descriptions
This section describes each user-accessible pin signal in detail. Although Table 10-3 grouped all channel
pins together, any TPM pin can be shared with the external clock source signal. Since I/O pin logic is not
part of the TPM, refer to full-chip documentation for a specific derivative for more details about the
interaction of TPM pin functions and general purpose I/O controls including port data, data direction, and
pullup controls.
MC9S08AC16 Series Data Sheet, Rev. 0
174
PRELIMINARY
Freescale Semiconductor
Chapter 10 Timer/PWM Module (S08TPMV3)
10.4.1.1
EXTCLK — External Clock Source
Control bits in the timer status and control register allow the user to select nothing (timer disable), the
bus-rate clock (the normal default source), a crystal-related clock, or an external clock as the clock which
drives the TPM prescaler and subsequently the 16-bit TPM counter. The external clock source is
synchronized in the TPM. The bus clock clocks the synchronizer; the frequency of the external source must
be no more than one-fourth the frequency of the bus-rate clock, to meet Nyquist criteria and allowing for
jitter.
The external clock signal shares the same pin as a channel I/O pin, so the channel pin will not be usable
for channel I/O function when selected as the external clock source. It is the user’s responsibility to avoid
such settings. If this pin is used as an external clock source (CLKSB:CLKSA = 1:1), the channel can still
be used in output compare mode as a software timer (ELSnB:ELSnA = 0:0).
10.4.1.2
TPMxCHn — TPM Channel n I/O Pin(s)
Each TPM channel is associated with an I/O pin on the MCU. The function of this pin depends on the
channel configuration. The TPM pins share with general purpose I/O pins, where each pin has a port data
register bit, and a data direction control bit, and the port has optional passive pullups which may be enabled
whenever a port pin is acting as an input.
The TPM channel does not control the I/O pin when (ELSnB:ELSnA = 0:0) or when (CLKSB:CLKSA =
0:0) so it normally reverts to general purpose I/O control. When CPWMS = 1 (and ELSnB:ELSnA not =
0:0), all channels within the TPM are configured for center-aligned PWM and the TPMxCHn pins are all
controlled by the TPM system. When CPWMS=0, the MSnB:MSnA control bits determine whether the
channel is configured for input capture, output compare, or edge-aligned PWM.
When a channel is configured for input capture (CPWMS=0, MSnB:MSnA = 0:0 and ELSnB:ELSnA not
= 0:0), the TPMxCHn pin is forced to act as an edge-sensitive input to the TPM. ELSnB:ELSnA control
bits determine what polarity edge or edges will trigger input-capture events. A synchronizer based on the
bus clock is used to synchronize input edges to the bus clock. This implies the minimum pulse width—that
can be reliably detected—on an input capture pin is four bus clock periods (with ideal clock pulses as near
as two bus clocks can be detected). TPM uses this pin as an input capture input to override the port data
and data direction controls for the same pin.
When a channel is configured for output compare (CPWMS=0, MSnB:MSnA = 0:1 and ELSnB:ELSnA
not = 0:0), the associated data direction control is overridden, the TPMxCHn pin is considered an output
controlled by the TPM, and the ELSnB:ELSnA control bits determine how the pin is controlled. The
remaining three combinations of ELSnB:ELSnA determine whether the TPMxCHn pin is toggled, cleared,
or set each time the 16-bit channel value register matches the timer counter.
When the output compare toggle mode is initially selected, the previous value on the pin is driven out until
the next output compare event—then the pin is toggled.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
175
Chapter 10 Timer/PWM Module (S08TPMV3)
When a channel is configured for edge-aligned PWM (CPWMS=0, MSnB=1 and ELSnB:ELSnA not =
0:0), the data direction is overridden, the TPMxCHn pin is forced to be an output controlled by the TPM,
and ELSnA controls the polarity of the PWM output signal on the pin. When ELSnB:ELSnA=1:0, the
TPMxCHn pin is forced high at the start of each new period (TPMxCNT=0x0000), and the pin is forced
low when the channel value register matches the timer counter. When ELSnA=1, the TPMxCHn pin is
forced low at the start of each new period (TPMxCNT=0x0000), and the pin is forced high when the
channel value register matches the timer counter.
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
...
0
1
2
3
4
5
6
7
8
0
1
2
...
2
...
TPMxCHn
CHnF BIT
TOF BIT
Figure 10-3. High-True Pulse of an Edge-Aligned PWM
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
...
0
1
2
3
4
5
6
7
8
0
1
TPMxCHn
CHnF BIT
TOF BIT
Figure 10-4. Low-True Pulse of an Edge-Aligned PWM
MC9S08AC16 Series Data Sheet, Rev. 0
176
PRELIMINARY
Freescale Semiconductor
Chapter 10 Timer/PWM Module (S08TPMV3)
When the TPM is configured for center-aligned PWM (and ELSnB:ELSnA not = 0:0), the data direction
for all channels in this TPM are overridden, the TPMxCHn pins are forced to be outputs controlled by the
TPM, and the ELSnA bits control the polarity of each TPMxCHn output. If ELSnB:ELSnA=1:0, the
corresponding TPMxCHn pin is cleared when the timer counter is counting up, and the channel value
register matches the timer counter; the TPMxCHn pin is set when the timer counter is counting down, and
the channel value register matches the timer counter. If ELSnA=1, the corresponding TPMxCHn pin is set
when the timer counter is counting up and the channel value register matches the timer counter; the
TPMxCHn pin is cleared when the timer counter is counting down and the channel value register matches
the timer counter.
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
...
7
8
7
6
5
4
3
2
1
0
1
2
3
4
5
6
7
8
7
6
5
...
7
8
7
6
5
...
TPMxCHn
CHnF BIT
TOF BIT
Figure 10-5. High-True Pulse of a Center-Aligned PWM
TPMxMODH:TPMxMODL = 0x0008
TPMxMODH:TPMxMODL = 0x0005
TPMxCNTH:TPMxCNTL
...
7
8
7
6
5
4
3
2
1
0
1
2
3
4
5
6
TPMxCHn
CHnF BIT
TOF BIT
Figure 10-6. Low-True Pulse of a Center-Aligned PWM
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
177
Chapter 10 Timer/PWM Module (S08TPMV3)
10.5
Register Definition
This section consists of register descriptions in address order. A typical MCU system may contain multiple
TPMs, and each TPM may have one to eight channels, so register names include placeholder characters to
identify which TPM and which channel is being referenced. For example, TPMxCnSC refers to timer
(TPM) x, channel n. TPM1C2SC would be the status and control register for channel 2 of timer 1.
10.5.1
TPM Status and Control Register (TPMxSC)
TPMxSC contains the overflow status flag and control bits used to configure the interrupt enable, TPM
configuration, clock source, and prescale factor. These controls relate to all channels within this timer
module.
7
R
TOF
W
0
Reset
0
6
5
4
3
2
1
0
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
0
0
0
0
0
0
0
Figure 10-7. TPM Status and Control Register (TPMxSC)
Table 10-4. TPMxSC Field Descriptions
Field
Description
7
TOF
Timer overflow flag. This read/write flag is set when the TPM counter resets to 0x0000 after reaching the modulo
value programmed in the TPM counter modulo registers. Clear TOF by reading the TPM status and control
register when TOF is set and then writing a logic 0 to TOF. If another TPM overflow occurs before the clearing
sequence is complete, the sequence is reset so TOF would remain set after the clear sequence was completed
for the earlier TOF. This is done so a TOF interrupt request cannot be lost during the clearing sequence for a
previous TOF. Reset clears TOF. Writing a logic 1 to TOF has no effect.
0 TPM counter has not reached modulo value or overflow
1 TPM counter has overflowed
6
TOIE
Timer overflow interrupt enable. This read/write bit enables TPM overflow interrupts. If TOIE is set, an interrupt is
generated when TOF equals one. Reset clears TOIE.
0 TOF interrupts inhibited (use for software polling)
1 TOF interrupts enabled
5
CPWMS
Center-aligned PWM select. When present, this read/write bit selects CPWM operating mode. By default, the
TPM operates in up-counting mode for input capture, output compare, and edge-aligned PWM functions. Setting
CPWMS reconfigures the TPM to operate in up/down counting mode for CPWM functions. Reset clears CPWMS.
0 All channels operate as input capture, output compare, or edge-aligned PWM mode as selected by the
MSnB:MSnA control bits in each channel’s status and control register.
1 All channels operate in center-aligned PWM mode.
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Table 10-4. TPMxSC Field Descriptions (continued)
Field
Description
4–3
Clock source selects. As shown in Table 10-5, this 2-bit field is used to disable the TPM system or select one of
CLKS[B:A] three clock sources to drive the counter prescaler. The fixed system clock source is only meaningful in systems
with a PLL-based system clock. When there is no PLL, the fixed-system clock source is the same as the bus rate
clock. The external source is synchronized to the bus clock by TPM module, and the fixed system clock source
(when a PLL is present) is synchronized to the bus clock by an on-chip synchronization circuit. When a PLL is
present but not enabled, the fixed-system clock source is the same as the bus-rate clock.
2–0
PS[2:0]
Prescale factor select. This 3-bit field selects one of 8 division factors for the TPM clock input as shown in
Table 10-6. This prescaler is located after any clock source synchronization or clock source selection so it affects
the clock source selected to drive the TPM system. The new prescale factor will affect the clock source on the
next system clock cycle after the new value is updated into the register bits.
Table 10-5. TPM-Clock-Source Selection
CLKSB:CLKSA
TPM Clock Source to Prescaler Input
00
No clock selected (TPM counter disable)
01
Bus rate clock
10
Fixed system clock
11
External source
Table 10-6. Prescale Factor Selection
10.5.2
PS2:PS1:PS0
TPM Clock Source Divided-by
000
1
001
2
010
4
011
8
100
16
101
32
110
64
111
128
TPM-Counter Registers (TPMxCNTH:TPMxCNTL)
The two read-only TPM counter registers contain the high and low bytes of the value in the TPM counter.
Reading either byte (TPMxCNTH or TPMxCNTL) latches the contents of both bytes into a buffer where
they remain latched until the other half is read. This allows coherent 16-bit reads in either big-endian or
little-endian order which makes this more friendly to various compiler implementations. The coherency
mechanism is automatically restarted by an MCU reset or any write to the timer status/control register
(TPMxSC).
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Reset clears the TPM counter registers. Writing any value to TPMxCNTH or TPMxCNTL also clears the
TPM counter (TPMxCNTH:TPMxCNTL) and resets the coherency mechanism, regardless of the data
involved in the write.
R
7
6
5
4
3
2
1
0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
W
Reset
Any write to TPMxCNTH clears the 16-bit counter
0
0
0
0
0
0
Figure 10-8. TPM Counter Register High (TPMxCNTH)
R
7
6
5
4
3
2
1
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
W
Reset
Any write to TPMxCNTL clears the 16-bit counter
0
0
0
0
0
0
Figure 10-9. TPM Counter Register Low (TPMxCNTL)
When BDM is active, the timer counter is frozen (this is the value that will be read by user); the coherency
mechanism is frozen such that the buffer latches remain in the state they were in when the BDM became
active, even if one or both counter halves are read while BDM is active. This assures that if the user was
in the middle of reading a 16-bit register when BDM became active, it will read the appropriate value from
the other half of the 16-bit value after returning to normal execution.
In BDM mode, writing any value to TPMxSC, TPMxCNTH or TPMxCNTL registers resets the read
coherency mechanism of the TPMxCNTH:L registers, regardless of the data involved in the write.
10.5.3
TPM Counter Modulo Registers (TPMxMODH:TPMxMODL)
The read/write TPM modulo registers contain the modulo value for the TPM counter. After the TPM
counter reaches the modulo value, the TPM counter resumes counting from 0x0000 at the next clock, and
the overflow flag (TOF) becomes set. Writing to TPMxMODH or TPMxMODL inhibits the TOF bit and
overflow interrupts until the other byte is written. Reset sets the TPM counter modulo registers to 0x0000
which results in a free running timer counter (modulo disabled).
Writing to either byte (TPMxMODH or TPMxMODL) latches the value into a buffer and the registers are
updated with the value of their write buffer according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), then the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), then the registers are updated after both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
the TPM counter is a free-running counter, the update is made when the TPM counter changes from
0xFFFE to 0xFFFF
The latching mechanism may be manually reset by writing to the TPMxSC address (whether BDM is
active or not).
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When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxSC register)
such that the buffer latches remain in the state they were in when the BDM became active, even if one or
both halves of the modulo register are written while BDM is active. Any write to the modulo registers
bypasses the buffer latches and directly writes to the modulo register while BDM is active.
7
6
5
4
3
2
1
0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 10-10. TPM Counter Modulo Register High (TPMxMODH)
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 10-11. TPM Counter Modulo Register Low (TPMxMODL)
Reset the TPM counter before writing to the TPM modulo registers to avoid confusion about when the first
counter overflow will occur.
10.5.4
TPM Channel n Status and Control Register (TPMxCnSC)
TPMxCnSC contains the channel-interrupt-status flag and control bits used to configure the interrupt
enable, channel configuration, and pin function.
7
R
6
5
4
3
2
CHnIE
MSnB
MSnA
ELSnB
ELSnA
0
0
0
0
0
CHnF
W
0
Reset
0
1
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-12. TPM Channel n Status and Control Register (TPMxCnSC)
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Table 10-7. TPMxCnSC Field Descriptions
Field
Description
7
CHnF
Channel n flag. When channel n is an input-capture channel, this read/write bit is set when an active edge occurs
on the channel n pin. When channel n is an output compare or edge-aligned/center-aligned PWM channel, CHnF
is set when the value in the TPM counter registers matches the value in the TPM channel n value registers. When
channel n is an edge-aligned/center-aligned PWM channel and the duty cycle is set to 0% or 100%, CHnF will
not be set even when the value in the TPM counter registers matches the value in the TPM channel n value
registers.
A corresponding interrupt is requested when CHnF is set and interrupts are enabled (CHnIE = 1). Clear CHnF by
reading TPMxCnSC while CHnF is set and then writing a logic 0 to CHnF. If another interrupt request occurs
before the clearing sequence is complete, the sequence is reset so CHnF remains set after the clear sequence
completed for the earlier CHnF. This is done so a CHnF interrupt request cannot be lost due to clearing a previous
CHnF.
Reset clears the CHnF bit. Writing a logic 1 to CHnF has no effect.
0 No input capture or output compare event occurred on channel n
1 Input capture or output compare event on channel n
6
CHnIE
Channel n interrupt enable. This read/write bit enables interrupts from channel n. Reset clears CHnIE.
0 Channel n interrupt requests disabled (use for software polling)
1 Channel n interrupt requests enabled
5
MSnB
Mode select B for TPM channel n. When CPWMS=0, MSnB=1 configures TPM channel n for edge-aligned PWM
mode. Refer to the summary of channel mode and setup controls in Table 10-8.
4
MSnA
Mode select A for TPM channel n. When CPWMS=0 and MSnB=0, MSnA configures TPM channel n for
input-capture mode or output compare mode. Refer to Table 10-8 for a summary of channel mode and setup
controls.
Note: If the associated port pin is not stable for at least two bus clock cycles before changing to input capture
mode, it is possible to get an unexpected indication of an edge trigger.
3–2
ELSnB
ELSnA
Edge/level select bits. Depending upon the operating mode for the timer channel as set by CPWMS:MSnB:MSnA
and shown in Table 10-8, these bits select the polarity of the input edge that triggers an input capture event, select
the level that will be driven in response to an output compare match, or select the polarity of the PWM output.
Setting ELSnB:ELSnA to 0:0 configures the related timer pin as a general purpose I/O pin not related to any timer
functions. This function is typically used to temporarily disable an input capture channel or to make the timer pin
available as a general purpose I/O pin when the associated timer channel is set up as a software timer that does
not require the use of a pin.
Table 10-8. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
X
XX
00
Mode
Configuration
Pin not used for TPM - revert to general
purpose I/O or other peripheral control
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Table 10-8. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
Mode
Configuration
0
00
01
Input capture
Capture on rising edge
only
01
10
Capture on falling edge
only
11
Capture on rising or
falling edge
01
1X
Output compare
10
Clear output on
compare
11
Set output on compare
10
Edge-aligned
PWM
X1
1
XX
High-true pulses (clear
output on compare)
Low-true pulses (set
output on compare)
10
Center-aligned
PWM
X1
10.5.5
Toggle output on
compare
High-true pulses (clear
output on compare-up)
Low-true pulses (set
output on compare-up)
TPM Channel Value Registers (TPMxCnVH:TPMxCnVL)
These read/write registers contain the captured TPM counter value of the input capture function or the
output compare value for the output compare or PWM functions. The channel registers are cleared by
reset.
7
6
5
4
3
2
1
0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
R
W
Reset
Figure 10-13. TPM Channel Value Register High (TPMxCnVH)
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 10-14. TPM Channel Value Register Low (TPMxCnVL)
In input capture mode, reading either byte (TPMxCnVH or TPMxCnVL) latches the contents of both bytes
into a buffer where they remain latched until the other half is read. This latching mechanism also resets
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(becomes unlatched) when the TPMxCnSC register is written (whether BDM mode is active or not). Any
write to the channel registers will be ignored during the input capture mode.
When BDM is active, the coherency mechanism is frozen (unless reset by writing to TPMxCnSC register)
such that the buffer latches remain in the state they were in when the BDM became active, even if one or
both halves of the channel register are read while BDM is active. This assures that if the user was in the
middle of reading a 16-bit register when BDM became active, it will read the appropriate value from the
other half of the 16-bit value after returning to normal execution. The value read from the TPMxCnVH
and TPMxCnVL registers in BDM mode is the value of these registers and not the value of their read
buffer.
In output compare or PWM modes, writing to either byte (TPMxCnVH or TPMxCnVL) latches the value
into a buffer. After both bytes are written, they are transferred as a coherent 16-bit value into the
timer-channel registers according to the value of CLKSB:CLKSA bits and the selected mode, so:
• If (CLKSB:CLKSA = 0:0), then the registers are updated when the second byte is written.
• If (CLKSB:CLKSA not = 0:0 and in output compare mode) then the registers are updated after the
second byte is written and on the next change of the TPM counter (end of the prescaler counting).
• If (CLKSB:CLKSA not = 0:0 and in EPWM or CPWM modes), then the registers are updated after
the both bytes were written, and the TPM counter changes from (TPMxMODH:TPMxMODL - 1)
to (TPMxMODH:TPMxMODL). If the TPM counter is a free-running counter then the update is
made when the TPM counter changes from 0xFFFE to 0xFFFF.
The latching mechanism may be manually reset by writing to the TPMxCnSC register (whether BDM
mode is active or not). This latching mechanism allows coherent 16-bit writes in either big-endian or
little-endian order which is friendly to various compiler implementations.
When BDM is active, the coherency mechanism is frozen such that the buffer latches remain in the state
they were in when the BDM became active even if one or both halves of the channel register are written
while BDM is active. Any write to the channel registers bypasses the buffer latches and directly write to
the channel register while BDM is active. The values written to the channel register while BDM is active
are used for PWM & output compare operation once normal execution resumes. Writes to the channel
registers while BDM is active do not interfere with partial completion of a coherency sequence. After the
coherency mechanism has been fully exercised, the channel registers are updated using the buffered values
written (while BDM was not active) by the user.
10.6
Functional Description
All TPM functions are associated with a central 16-bit counter which allows flexible selection of the clock
source and prescale factor. There is also a 16-bit modulo register associated with the main counter.
The CPWMS control bit chooses between center-aligned PWM operation for all channels in the TPM
(CPWMS=1) or general purpose timing functions (CPWMS=0) where each channel can independently be
configured to operate in input capture, output compare, or edge-aligned PWM mode. The CPWMS control
bit is located in the main TPM status and control register because it affects all channels within the TPM
and influences the way the main counter operates. (In CPWM mode, the counter changes to an up/down
mode rather than the up-counting mode used for general purpose timer functions.)
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The following sections describe the main counter and each of the timer operating modes (input capture,
output compare, edge-aligned PWM, and center-aligned PWM). Because details of pin operation and
interrupt activity depend upon the operating mode, these topics will be covered in the associated mode
explanation sections.
10.6.1
Counter
All timer functions are based on the main 16-bit counter (TPMxCNTH:TPMxCNTL). This section
discusses selection of the clock source, end-of-count overflow, up-counting vs. up/down counting, and
manual counter reset.
10.6.1.1
Counter Clock Source
The 2-bit field, CLKSB:CLKSA, in the timer status and control register (TPMxSC) selects one of three
possible clock sources or OFF (which effectively disables the TPM). See Table 10-5. After any MCU reset,
CLKSB:CLKSA=0:0 so no clock source is selected, and the TPM is in a very low power state. These
control bits may be read or written at any time and disabling the timer (writing 00 to the CLKSB:CLKSA
field) does not affect the values in the counter or other timer registers.
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Table 10-9. TPM Clock Source Selection
CLKSB:CLKSA
TPM Clock Source to Prescaler Input
00
No clock selected (TPM counter disabled)
01
Bus rate clock
10
Fixed system clock
11
External source
The bus rate clock is the main system bus clock for the MCU. This clock source requires no
synchronization because it is the clock that is used for all internal MCU activities including operation of
the CPU and buses.
In MCUs that have no PLL or the PLL is not engaged, the fixed system clock source is the same as the
bus-rate-clock source, and it does not go through a synchronizer. When a PLL is present and engaged, a
synchronizer is required between the crystal divided-by two clock source and the timer counter so counter
transitions will be properly aligned to bus-clock transitions. A synchronizer will be used at chip level to
synchronize the crystal-related source clock to the bus clock.
The external clock source may be connected to any TPM channel pin. This clock source always has to pass
through a synchronizer to assure that counter transitions are properly aligned to bus clock transitions. The
bus-rate clock drives the synchronizer; therefore, to meet Nyquist criteria even with jitter, the frequency of
the external clock source must not be faster than the bus rate divided-by four. With ideal clocks the external
clock can be as fast as bus clock divided by four.
When the external clock source shares the TPM channel pin, this pin should not be used for other channel
timing functions. For example, it would be ambiguous to configure channel 0 for input capture when the
TPM channel 0 pin was also being used as the timer external clock source. (It is the user’s responsibility
to avoid such settings.) The TPM channel could still be used in output compare mode for software timing
functions (pin controls set not to affect the TPM channel pin).
10.6.1.2
Counter Overflow and Modulo Reset
An interrupt flag and enable are associated with the 16-bit main counter. The flag (TOF) is a
software-accessible indication that the timer counter has overflowed. The enable signal selects between
software polling (TOIE=0) where no hardware interrupt is generated, or interrupt-driven operation
(TOIE=1) where a static hardware interrupt is generated whenever the TOF flag is equal to one.
The conditions causing TOF to become set depend on whether the TPM is configured for center-aligned
PWM (CPWMS=1). In the simplest mode, there is no modulus limit and the TPM is not in CPWMS=1
mode. In this case, the 16-bit timer counter counts from 0x0000 through 0xFFFF and overflows to 0x0000
on the next counting clock. TOF becomes set at the transition from 0xFFFF to 0x0000. When a modulus
limit is set, TOF becomes set at the transition from the value set in the modulus register to 0x0000. When
the TPM is in center-aligned PWM mode (CPWMS=1), the TOF flag gets set as the counter changes
direction at the end of the count value set in the modulus register (that is, at the transition from the value
set in the modulus register to the next lower count value). This corresponds to the end of a PWM period
(the 0x0000 count value corresponds to the center of a period).
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10.6.1.3
Counting Modes
The main timer counter has two counting modes. When center-aligned PWM is selected (CPWMS=1), the
counter operates in up/down counting mode. Otherwise, the counter operates as a simple up counter. As
an up counter, the timer counter counts from 0x0000 through its terminal count and then continues with
0x0000. The terminal count is 0xFFFF or a modulus value in TPMxMODH:TPMxMODL.
When center-aligned PWM operation is specified, the counter counts up from 0x0000 through its terminal
count and then down to 0x0000 where it changes back to up counting. Both 0x0000 and the terminal count
value are normal length counts (one timer clock period long). In this mode, the timer overflow flag (TOF)
becomes set at the end of the terminal-count period (as the count changes to the next lower count value).
10.6.1.4
Manual Counter Reset
The main timer counter can be manually reset at any time by writing any value to either half of
TPMxCNTH or TPMxCNTL. Resetting the counter in this manner also resets the coherency mechanism
in case only half of the counter was read before resetting the count.
10.6.2
Channel Mode Selection
Provided CPWMS=0, the MSnB and MSnA control bits in the channel n status and control registers
determine the basic mode of operation for the corresponding channel. Choices include input capture,
output compare, and edge-aligned PWM.
10.6.2.1
Input Capture Mode
With the input-capture function, the TPM can capture the time at which an external event occurs. When an
active edge occurs on the pin of an input-capture channel, the TPM latches the contents of the TPM counter
into the channel-value registers (TPMxCnVH:TPMxCnVL). Rising edges, falling edges, or any edge may
be chosen as the active edge that triggers an input capture.
In input capture mode, the TPMxCnVH and TPMxCnVL registers are read only.
When either half of the 16-bit capture register is read, the other half is latched into a buffer to support
coherent 16-bit accesses in big-endian or little-endian order. The coherency sequence can be manually
reset by writing to the channel status/control register (TPMxCnSC).
An input capture event sets a flag bit (CHnF) which may optionally generate a CPU interrupt request.
While in BDM, the input capture function works as configured by the user. When an external event occurs,
the TPM latches the contents of the TPM counter (which is frozen because of the BDM mode) into the
channel value registers and sets the flag bit.
10.6.2.2
Output Compare Mode
With the output-compare function, the TPM can generate timed pulses with programmable position,
polarity, duration, and frequency. When the counter reaches the value in the channel-value registers of an
output-compare channel, the TPM can set, clear, or toggle the channel pin.
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In output compare mode, values are transferred to the corresponding timer channel registers only after both
8-bit halves of a 16-bit register have been written and according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated at the next change of the TPM counter
(end of the prescaler counting) after the second byte is written.
The coherency sequence can be manually reset by writing to the channel status/control register
(TPMxCnSC).
An output compare event sets a flag bit (CHnF) which may optionally generate a CPU-interrupt request.
10.6.2.3
Edge-Aligned PWM Mode
This type of PWM output uses the normal up-counting mode of the timer counter (CPWMS=0) and can
be used when other channels in the same TPM are configured for input capture or output compare
functions. The period of this PWM signal is determined by the value of the modulus register
(TPMxMODH:TPMxMODL) plus 1. The duty cycle is determined by the setting in the timer channel
register (TPMxCnVH:TPMxCnVL). The polarity of this PWM signal is determined by the setting in the
ELSnA control bit. 0% and 100% duty cycle cases are possible.
The output compare value in the TPM channel registers determines the pulse width (duty cycle) of the
PWM signal (Figure 10-15). The time between the modulus overflow and the output compare is the pulse
width. If ELSnA=0, the counter overflow forces the PWM signal high, and the output compare forces the
PWM signal low. If ELSnA=1, the counter overflow forces the PWM signal low, and the output compare
forces the PWM signal high.
OVERFLOW
OVERFLOW
OVERFLOW
PERIOD
PULSE
WIDTH
TPMxCHn
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 10-15. PWM Period and Pulse Width (ELSnA=0)
When the channel value register is set to 0x0000, the duty cycle is 0%. 100% duty cycle can be achieved
by setting the timer-channel register (TPMxCnVH:TPMxCnVL) to a value greater than the modulus
setting. This implies that the modulus setting must be less than 0xFFFF in order to get 100% duty cycle.
Because the TPM may be used in an 8-bit MCU, the settings in the timer channel registers are buffered to
ensure coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers
TPMxCnVH and TPMxCnVL, actually write to buffer registers. In edge-aligned PWM mode, values are
transferred to the corresponding timer-channel registers according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated after the both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
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the TPM counter is a free-running counter then the update is made when the TPM counter changes
from 0xFFFE to 0xFFFF.
10.6.2.4
Center-Aligned PWM Mode
This type of PWM output uses the up/down counting mode of the timer counter (CPWMS=1). The output
compare value in TPMxCnVH:TPMxCnVL determines the pulse width (duty cycle) of the PWM signal
while the period is determined by the value in TPMxMODH:TPMxMODL. TPMxMODH:TPMxMODL
should be kept in the range of 0x0001 to 0x7FFF because values outside this range can produce ambiguous
results. ELSnA will determine the polarity of the CPWM output.
pulse width = 2 x (TPMxCnVH:TPMxCnVL)
period = 2 x (TPMxMODH:TPMxMODL); TPMxMODH:TPMxMODL=0x0001-0x7FFF
If the channel-value register TPMxCnVH:TPMxCnVL is zero or negative (bit 15 set), the duty cycle will
be 0%. If TPMxCnVH:TPMxCnVL is a positive value (bit 15 clear) and is greater than the (non-zero)
modulus setting, the duty cycle will be 100% because the duty cycle compare will never occur. This
implies the usable range of periods set by the modulus register is 0x0001 through 0x7FFE (0x7FFF if you
do not need to generate 100% duty cycle). This is not a significant limitation. The resulting period would
be much longer than required for normal applications.
TPMxMODH:TPMxMODL=0x0000 is a special case that should not be used with center-aligned PWM
mode. When CPWMS=0, this case corresponds to the counter running free from 0x0000 through 0xFFFF,
but when CPWMS=1 the counter needs a valid match to the modulus register somewhere other than at
0x0000 in order to change directions from up-counting to down-counting.
The output compare value in the TPM channel registers (times 2) determines the pulse width (duty cycle)
of the CPWM signal (Figure 10-16). If ELSnA=0, a compare occurred while counting up forces the
CPWM output signal low and a compare occurred while counting down forces the output high. The
counter counts up until it reaches the modulo setting in TPMxMODH:TPMxMODL, then counts down
until it reaches zero. This sets the period equal to two times TPMxMODH:TPMxMODL.
COUNT= 0
OUTPUT
COUNT=
COMPARE
TPMxMODH:TPMxMODL (COUNT DOWN)
OUTPUT
COMPARE
(COUNT UP)
COUNT=
TPMxMODH:TPMxMODL
TPMxCHn
PULSE WIDTH
2 x TPMxCnVH:TPMxCnVL
PERIOD
2 x TPMxMODH:TPMxMODL
Figure 10-16. CPWM Period and Pulse Width (ELSnA=0)
Center-aligned PWM outputs typically produce less noise than edge-aligned PWMs because fewer I/O pin
transitions are lined up at the same system clock edge. This type of PWM is also required for some types
of motor drives.
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Chapter 10 Timer/PWM Module (S08TPMV3)
Input capture, output compare, and edge-aligned PWM functions do not make sense when the counter is
operating in up/down counting mode so this implies that all active channels within a TPM must be used in
CPWM mode when CPWMS=1.
The TPM may be used in an 8-bit MCU. The settings in the timer channel registers are buffered to ensure
coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers
TPMxMODH, TPMxMODL, TPMxCnVH, and TPMxCnVL, actually write to buffer registers.
In center-aligned PWM mode, the TPMxCnVH:L registers are updated with the value of their write buffer
according to the value of CLKSB:CLKSA bits, so:
• If (CLKSB:CLKSA = 0:0), the registers are updated when the second byte is written
• If (CLKSB:CLKSA not = 0:0), the registers are updated after the both bytes were written, and the
TPM counter changes from (TPMxMODH:TPMxMODL - 1) to (TPMxMODH:TPMxMODL). If
the TPM counter is a free-running counter, the update is made when the TPM counter changes from
0xFFFE to 0xFFFF.
When TPMxCNTH:TPMxCNTL=TPMxMODH:TPMxMODL, the TPM can optionally generate a TOF
interrupt (at the end of this count).
Writing to TPMxSC cancels any values written to TPMxMODH and/or TPMxMODL and resets the
coherency mechanism for the modulo registers. Writing to TPMxCnSC cancels any values written to the
channel value registers and resets the coherency mechanism for TPMxCnVH:TPMxCnVL.
10.7
10.7.1
Reset Overview
General
The TPM is reset whenever any MCU reset occurs.
10.7.2
Description of Reset Operation
Reset clears the TPMxSC register which disables clocks to the TPM and disables timer overflow interrupts
(TOIE=0). CPWMS, MSnB, MSnA, ELSnB, and ELSnA are all cleared which configures all TPM
channels for input-capture operation with the associated pins disconnected from I/O pin logic (so all MCU
pins related to the TPM revert to general purpose I/O pins).
10.8
10.8.1
Interrupts
General
The TPM generates an optional interrupt for the main counter overflow and an interrupt for each channel.
The meaning of channel interrupts depends on each channel’s mode of operation. If the channel is
configured for input capture, the interrupt flag is set each time the selected input capture edge is
recognized. If the channel is configured for output compare or PWM modes, the interrupt flag is set each
time the main timer counter matches the value in the 16-bit channel value register.
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Freescale Semiconductor
Chapter 10 Timer/PWM Module (S08TPMV3)
All TPM interrupts are listed in Table 10-10 which shows the interrupt name, the name of any local enable
that can block the interrupt request from leaving the TPM and getting recognized by the separate interrupt
processing logic.
Table 10-10. Interrupt Summary
Interrupt
Local
Enable
Source
Description
TOF
TOIE
Counter overflow
Set each time the timer counter reaches its terminal
count (at transition to next count value which is
usually 0x0000)
CHnF
CHnIE
Channel event
An input capture or output compare event took
place on channel n
The TPM module will provide a high-true interrupt signal. Vectors and priorities are determined at chip
integration time in the interrupt module so refer to the user’s guide for the interrupt module or to the chip’s
complete documentation for details.
10.8.2
Description of Interrupt Operation
For each interrupt source in the TPM, a flag bit is set upon recognition of the interrupt condition such as
timer overflow, channel-input capture, or output-compare events. This flag may be read (polled) by
software to determine that the action has occurred, or an associated enable bit (TOIE or CHnIE) can be set
to enable hardware interrupt generation. While the interrupt enable bit is set, a static interrupt will generate
whenever the associated interrupt flag equals one. The user’s software must perform a sequence of steps
to clear the interrupt flag before returning from the interrupt-service routine.
TPM interrupt flags are cleared by a two-step process including a read of the flag bit while it is set (1)
followed by a write of zero (0) to the bit. If a new event is detected between these two steps, the sequence
is reset and the interrupt flag remains set after the second step to avoid the possibility of missing the new
event.
10.8.2.1
Timer Overflow Interrupt (TOF) Description
The meaning and details of operation for TOF interrupts varies slightly depending upon the mode of
operation of the TPM system (general purpose timing functions versus center-aligned PWM operation).
The flag is cleared by the two step sequence described above.
10.8.2.1.1
Normal Case
Normally TOF is set when the timer counter changes from 0xFFFF to 0x0000. When the TPM is not
configured for center-aligned PWM (CPWMS=0), TOF gets set when the timer counter changes from the
terminal count (the value in the modulo register) to 0x0000. This case corresponds to the normal meaning
of counter overflow.
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PRELIMINARY
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Chapter 10 Timer/PWM Module (S08TPMV3)
10.8.2.1.2
Center-Aligned PWM Case
When CPWMS=1, TOF gets set when the timer counter changes direction from up-counting to
down-counting at the end of the terminal count (the value in the modulo register). In this case the TOF
corresponds to the end of a PWM period.
10.8.2.2
Channel Event Interrupt Description
The meaning of channel interrupts depends on the channel’s current mode (input-capture, output-compare,
edge-aligned PWM, or center-aligned PWM).
10.8.2.2.1
Input Capture Events
When a channel is configured as an input capture channel, the ELSnB:ELSnA control bits select no edge
(off), rising edges, falling edges or any edge as the edge which triggers an input capture event. When the
selected edge is detected, the interrupt flag is set. The flag is cleared by the two-step sequence described
in Section 10.8.2, “Description of Interrupt Operation.”
10.8.2.2.2
Output Compare Events
When a channel is configured as an output compare channel, the interrupt flag is set each time the main
timer counter matches the 16-bit value in the channel value register. The flag is cleared by the two-step
sequence described Section 10.8.2, “Description of Interrupt Operation.”
10.8.2.2.3
PWM End-of-Duty-Cycle Events
For channels configured for PWM operation there are two possibilities. When the channel is configured
for edge-aligned PWM, the channel flag gets set when the timer counter matches the channel value register
which marks the end of the active duty cycle period. When the channel is configured for center-aligned
PWM, the timer count matches the channel value register twice during each PWM cycle. In this CPWM
case, the channel flag is set at the start and at the end of the active duty cycle period which are the times
when the timer counter matches the channel value register. The flag is cleared by the two-step sequence
described Section 10.8.2, “Description of Interrupt Operation.”
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Freescale Semiconductor
Chapter 11
Serial Communications Interface (S08SCIV4)
11.1
Introduction
The MC9S08AC16 Series includes two independent serial communications interface (SCI) modules
which are sometimes called universal asynchronous receiver/transmitters (UARTs). Typically, these
systems are used to connect to the RS232 serial input/output (I/O) port of a personal computer or
workstation, but they can also be used to communicate with other embedded controllers.
A flexible, 13-bit, modulo-based baud rate generator supports a broad range of standard baud rates beyond
115.2 kbaud. Transmit and receive within the same SCI use a common baud rate, and each SCI module
has a separate baud rate generator.
This SCI system offers many advanced features not commonly found on other asynchronous serial I/O
peripherals on other embedded controllers. The receiver employs an advanced data sampling technique
that ensures reliable communication and noise detection. Hardware parity, receiver wakeup, and double
buffering on transmit and receive are also included.
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
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10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 11 Serial Communications Interface (S08SCIV4)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 11-1. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Chapter 11 Serial Communications Interface (S08SCIV4)
11.1.1
Features
Features of SCI module include:
• Full-duplex, standard non-return-to-zero (NRZ) format
• Double-buffered transmitter and receiver with separate enables
• Programmable baud rates (13-bit modulo divider)
• Interrupt-driven or polled operation:
— Transmit data register empty and transmission complete
— Receive data register full
— Receive overrun, parity error, framing error, and noise error
— Idle receiver detect
— Active edge on receive pin
— Break detect supporting LIN
• Hardware parity generation and checking
• Programmable 8-bit or 9-bit character length
• Receiver wakeup by idle-line or address-mark
• Optional 13-bit break character generation / 11-bit break character detection
• Selectable transmitter output polarity
11.1.2
Modes of Operation
See Section 11.3, “Functional Description,” For details concerning SCI operation in these modes:
• 8- and 9-bit data modes
• Stop mode operation
• Loop mode
• Single-wire mode
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PRELIMINARY
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Chapter 11 Serial Communications Interface (S08SCIV4)
11.1.3
Block Diagram
Figure 11-2 shows the transmitter portion of the SCI.
INTERNAL BUS
(WRITE-ONLY)
LOOPS
SCID – Tx BUFFER
RSRC
LOOP
CONTROL
STOP
M
START
11-BIT TRANSMIT SHIFT REGISTER
8
7
6
5
4
3
2
1
0
TO TxD PIN
L
LSB
H
1 × BAUD
RATE CLOCK
TO RECEIVE
DATA IN
SHIFT DIRECTION
PT
BREAK (ALL 0s)
PARITY
GENERATION
PREAMBLE (ALL 1s)
PE
SHIFT ENABLE
T8
LOAD FROM SCIxD
TXINV
SCI CONTROLS TxD
TE
SBK
TRANSMIT CONTROL
TXDIR
TxD DIRECTION
TO TxD
PIN LOGIC
BRK13
TDRE
TIE
TC
Tx INTERRUPT
REQUEST
TCIE
Figure 11-2. SCI Transmitter Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Chapter 11 Serial Communications Interface (S08SCIV4)
Figure 11-3 shows the receiver portion of the SCI.
INTERNAL BUS
(READ-ONLY)
16 × BAUD
RATE CLOCK
DIVIDE
BY 16
SCID – Rx BUFFER
FROM RxD PIN
RXINV
LBKDE
H
DATA RECOVERY
WAKE
ILT
8
7
6
5
4
3
2
1
START
M
LSB
RSRC
11-BIT RECEIVE SHIFT REGISTER
MSB
SINGLE-WIRE
LOOP CONTROL
ALL 1s
LOOPS
STOP
FROM
TRANSMITTER
0
L
SHIFT DIRECTION
WAKEUP
LOGIC
RWU
RWUID
ACTIVE EDGE
DETECT
RDRF
RIE
IDLE
ILIE
LBKDIF
Rx INTERRUPT
REQUEST
LBKDIE
RXEDGIF
RXEDGIE
OR
ORIE
FE
FEIE
ERROR INTERRUPT
REQUEST
NF
NEIE
PE
PT
PARITY
CHECKING
PF
PEIE
Figure 11-3. SCI Receiver Block Diagram
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PRELIMINARY
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Chapter 11 Serial Communications Interface (S08SCIV4)
11.2
Register Definition
The SCI has eight 8-bit registers to control baud rate, select SCI options, report SCI status, and for
transmit/receive data.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all SCI registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
11.2.1
SCI Baud Rate Registers (SCIxBDH, SCIxBDL)
This pair of registers controls the prescale divisor for SCI baud rate generation. To update the 13-bit baud
rate setting [SBR12:SBR0], first write to SCIxBDH to buffer the high half of the new value and then write
to SCIxBDL. The working value in SCIxBDH does not change until SCIxBDL is written.
SCIxBDL is reset to a non-zero value, so after reset the baud rate generator remains disabled until the first
time the receiver or transmitter is enabled (RE or TE bits in SCIxC2 are written to 1).
7
6
5
LBKDIE
RXEDGIE
0
0
R
4
3
2
1
0
SBR12
SBR11
SBR10
SBR9
SBR8
0
0
0
0
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 11-4. SCI Baud Rate Register (SCIxBDH)
Table 11-1. SCIxBDH Field Descriptions
Field
7
LBKDIE
Description
LIN Break Detect Interrupt Enable (for LBKDIF)
0 Hardware interrupts from LBKDIF disabled (use polling).
1 Hardware interrupt requested when LBKDIF flag is 1.
6
RXEDGIE
RxD Input Active Edge Interrupt Enable (for RXEDGIF)
0 Hardware interrupts from RXEDGIF disabled (use polling).
1 Hardware interrupt requested when RXEDGIF flag is 1.
4:0
SBR[12:8]
Baud Rate Modulo Divisor — The 13 bits in SBR[12:0] are referred to collectively as BR, and they set the
modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to
reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16×BR). See also BR bits in
Table 11-2.
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Chapter 11 Serial Communications Interface (S08SCIV4)
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 11-5. SCI Baud Rate Register (SCIxBDL)
Table 11-2. SCIxBDL Field Descriptions
Field
7:0
SBR[7:0]
11.2.2
Description
Baud Rate Modulo Divisor — These 13 bits in SBR[12:0] are referred to collectively as BR, and they set the
modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to
reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16×BR). See also BR bits in
Table 11-1.
SCI Control Register 1 (SCIxC1)
This read/write register is used to control various optional features of the SCI system.
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 11-6. SCI Control Register 1 (SCIxC1)
Table 11-3. SCIxC1 Field Descriptions
Field
7
LOOPS
6
SCISWAI
5
RSRC
4
M
Description
Loop Mode Select — Selects between loop back modes and normal 2-pin full-duplex modes. When
LOOPS = 1, the transmitter output is internally connected to the receiver input.
0 Normal operation — RxD and TxD use separate pins.
1 Loop mode or single-wire mode where transmitter outputs are internally connected to receiver input. (See
RSRC bit.) RxD pin is not used by SCI.
SCI Stops in Wait Mode
0 SCI clocks continue to run in wait mode so the SCI can be the source of an interrupt that wakes up the CPU.
1 SCI clocks freeze while CPU is in wait mode.
Receiver Source Select — This bit has no meaning or effect unless the LOOPS bit is set to 1. When
LOOPS = 1, the receiver input is internally connected to the TxD pin and RSRC determines whether this
connection is also connected to the transmitter output.
0 Provided LOOPS = 1, RSRC = 0 selects internal loop back mode and the SCI does not use the RxD pins.
1 Single-wire SCI mode where the TxD pin is connected to the transmitter output and receiver input.
9-Bit or 8-Bit Mode Select
0 Normal — start + 8 data bits (LSB first) + stop.
1 Receiver and transmitter use 9-bit data characters
start + 8 data bits (LSB first) + 9th data bit + stop.
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Chapter 11 Serial Communications Interface (S08SCIV4)
Table 11-3. SCIxC1 Field Descriptions (continued)
Field
3
WAKE
Description
Receiver Wakeup Method Select — Refer to Section 11.3.3.2, “Receiver Wakeup Operation” for more
information.
0 Idle-line wakeup.
1 Address-mark wakeup.
2
ILT
Idle Line Type Select — Setting this bit to 1 ensures that the stop bit and logic 1 bits at the end of a character
do not count toward the 10 or 11 bit times of logic high level needed by the idle line detection logic. Refer to
Section 11.3.3.2.1, “Idle-Line Wakeup” for more information.
0 Idle character bit count starts after start bit.
1 Idle character bit count starts after stop bit.
1
PE
Parity Enable — Enables hardware parity generation and checking. When parity is enabled, the most significant
bit (MSB) of the data character (eighth or ninth data bit) is treated as the parity bit.
0 No hardware parity generation or checking.
1 Parity enabled.
0
PT
Parity Type — Provided parity is enabled (PE = 1), this bit selects even or odd parity. Odd parity means the total
number of 1s in the data character, including the parity bit, is odd. Even parity means the total number of 1s in
the data character, including the parity bit, is even.
0 Even parity.
1 Odd parity.
11.2.3
SCI Control Register 2 (SCIxC2)
This register can be read or written at any time.
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 11-7. SCI Control Register 2 (SCIxC2)
Table 11-4. SCIxC2 Field Descriptions
Field
7
TIE
6
TCIE
Description
Transmit Interrupt Enable (for TDRE)
0 Hardware interrupts from TDRE disabled (use polling).
1 Hardware interrupt requested when TDRE flag is 1.
Transmission Complete Interrupt Enable (for TC)
0 Hardware interrupts from TC disabled (use polling).
1 Hardware interrupt requested when TC flag is 1.
5
RIE
Receiver Interrupt Enable (for RDRF)
0 Hardware interrupts from RDRF disabled (use polling).
1 Hardware interrupt requested when RDRF flag is 1.
4
ILIE
Idle Line Interrupt Enable (for IDLE)
0 Hardware interrupts from IDLE disabled (use polling).
1 Hardware interrupt requested when IDLE flag is 1.
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Chapter 11 Serial Communications Interface (S08SCIV4)
Table 11-4. SCIxC2 Field Descriptions (continued)
Field
Description
3
TE
Transmitter Enable
0 Transmitter off.
1 Transmitter on.
TE must be 1 in order to use the SCI transmitter. When TE = 1, the SCI forces the TxD pin to act as an output
for the SCI system.
When the SCI is configured for single-wire operation (LOOPS = RSRC = 1), TXDIR controls the direction of
traffic on the single SCI communication line (TxD pin).
TE also can be used to queue an idle character by writing TE = 0 then TE = 1 while a transmission is in progress.
Refer to Section 11.3.2.1, “Send Break and Queued Idle” for more details.
When TE is written to 0, the transmitter keeps control of the port TxD pin until any data, queued idle, or queued
break character finishes transmitting before allowing the pin to revert to a general-purpose I/O pin.
2
RE
Receiver Enable — When the SCI receiver is off, the RxD pin reverts to being a general-purpose port I/O pin.
If LOOPS = 1 the RxD pin reverts to being a general-purpose I/O pin even if RE = 1.
0 Receiver off.
1 Receiver on.
1
RWU
Receiver Wakeup Control — This bit can be written to 1 to place the SCI receiver in a standby state where it
waits for automatic hardware detection of a selected wakeup condition. The wakeup condition is either an idle
line between messages (WAKE = 0, idle-line wakeup), or a logic 1 in the most significant data bit in a character
(WAKE = 1, address-mark wakeup). Application software sets RWU and (normally) a selected hardware
condition automatically clears RWU. Refer to Section 11.3.3.2, “Receiver Wakeup Operation” for more details.
0 Normal SCI receiver operation.
1 SCI receiver in standby waiting for wakeup condition.
0
SBK
Send Break — Writing a 1 and then a 0 to SBK queues a break character in the transmit data stream. Additional
break characters of 10 or 11 (13 or 14 if BRK13 = 1) bit times of logic 0 are queued as long as SBK = 1.
Depending on the timing of the set and clear of SBK relative to the information currently being transmitted, a
second break character may be queued before software clears SBK. Refer to Section 11.3.2.1, “Send Break and
Queued Idle” for more details.
0 Normal transmitter operation.
1 Queue break character(s) to be sent.
11.2.4
SCI Status Register 1 (SCIxS1)
This register has eight read-only status flags. Writes have no effect. Special software sequences (which do
not involve writing to this register) are used to clear these status flags.
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 11-8. SCI Status Register 1 (SCIxS1)
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Chapter 11 Serial Communications Interface (S08SCIV4)
Table 11-5. SCIxS1 Field Descriptions
Field
Description
7
TDRE
Transmit Data Register Empty Flag — TDRE is set out of reset and when a transmit data value transfers from
the transmit data buffer to the transmit shifter, leaving room for a new character in the buffer. To clear TDRE, read
SCIxS1 with TDRE = 1 and then write to the SCI data register (SCIxD).
0 Transmit data register (buffer) full.
1 Transmit data register (buffer) empty.
6
TC
Transmission Complete Flag — TC is set out of reset and when TDRE = 1 and no data, preamble, or break
character is being transmitted.
0 Transmitter active (sending data, a preamble, or a break).
1 Transmitter idle (transmission activity complete).
TC is cleared automatically by reading SCIxS1 with TC = 1 and then doing one of the following three things:
• Write to the SCI data register (SCIxD) to transmit new data
• Queue a preamble by changing TE from 0 to 1
• Queue a break character by writing 1 to SBK in SCIxC2
5
RDRF
Receive Data Register Full Flag — RDRF becomes set when a character transfers from the receive shifter into
the receive data register (SCIxD). To clear RDRF, read SCIxS1 with RDRF = 1 and then read the SCI data
register (SCIxD).
0 Receive data register empty.
1 Receive data register full.
4
IDLE
Idle Line Flag — IDLE is set when the SCI receive line becomes idle for a full character time after a period of
activity. When ILT = 0, the receiver starts counting idle bit times after the start bit. So if the receive character is
all 1s, these bit times and the stop bit time count toward the full character time of logic high (10 or 11 bit times
depending on the M control bit) needed for the receiver to detect an idle line. When ILT = 1, the receiver doesn’t
start counting idle bit times until after the stop bit. So the stop bit and any logic high bit times at the end of the
previous character do not count toward the full character time of logic high needed for the receiver to detect an
idle line.
To clear IDLE, read SCIxS1 with IDLE = 1 and then read the SCI data register (SCIxD). After IDLE has been
cleared, it cannot become set again until after a new character has been received and RDRF has been set. IDLE
will get set only once even if the receive line remains idle for an extended period.
0 No idle line detected.
1 Idle line was detected.
3
OR
Receiver Overrun Flag — OR is set when a new serial character is ready to be transferred to the receive data
register (buffer), but the previously received character has not been read from SCIxD yet. In this case, the new
character (and all associated error information) is lost because there is no room to move it into SCIxD. To clear
OR, read SCIxS1 with OR = 1 and then read the SCI data register (SCIxD).
0 No overrun.
1 Receive overrun (new SCI data lost).
2
NF
Noise Flag — The advanced sampling technique used in the receiver takes seven samples during the start bit
and three samples in each data bit and the stop bit. If any of these samples disagrees with the rest of the samples
within any bit time in the frame, the flag NF will be set at the same time as the flag RDRF gets set for the
character. To clear NF, read SCIxS1 and then read the SCI data register (SCIxD).
0 No noise detected.
1 Noise detected in the received character in SCIxD.
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Table 11-5. SCIxS1 Field Descriptions (continued)
Field
Description
1
FE
Framing Error Flag — FE is set at the same time as RDRF when the receiver detects a logic 0 where the stop
bit was expected. This suggests the receiver was not properly aligned to a character frame. To clear FE, read
SCIxS1 with FE = 1 and then read the SCI data register (SCIxD).
0 No framing error detected. This does not guarantee the framing is correct.
1 Framing error.
0
PF
Parity Error Flag — PF is set at the same time as RDRF when parity is enabled (PE = 1) and the parity bit in
the received character does not agree with the expected parity value. To clear PF, read SCIxS1 and then read
the SCI data register (SCIxD).
0 No parity error.
1 Parity error.
11.2.5
SCI Status Register 2 (SCIxS2)
This register has one read-only status flag.
7
6
LBKDIF
RXEDGIF
0
0
R
5
4
3
2
1
RXINV
RWUID
BRK13
LBKDE
0
0
0
0
0
0
RAF
W
Reset
0
0
= Unimplemented or Reserved
Figure 11-9. SCI Status Register 2 (SCIxS2)
Table 11-6. SCIxS2 Field Descriptions
Field
Description
7
LBKDIF
LIN Break Detect Interrupt Flag — LBKDIF is set when the LIN break detect circuitry is enabled and a LIN break
character is detected. LBKDIF is cleared by writing a “1” to it.
0 No LIN break character has been detected.
1 LIN break character has been detected.
6
RXEDGIF
RxD Pin Active Edge Interrupt Flag — RXEDGIF is set when an active edge (falling if RXINV = 0, rising if
RXINV=1) on the RxD pin occurs. RXEDGIF is cleared by writing a “1” to it.
0 No active edge on the receive pin has occurred.
1 An active edge on the receive pin has occurred.
4
RXINV1
Receive Data Inversion — Setting this bit reverses the polarity of the received data input.
0 Receive data not inverted
1 Receive data inverted
3
RWUID
Receive Wake Up Idle Detect— RWUID controls whether the idle character that wakes up the receiver sets the
IDLE bit.
0 During receive standby state (RWU = 1), the IDLE bit does not get set upon detection of an idle character.
1 During receive standby state (RWU = 1), the IDLE bit gets set upon detection of an idle character.
2
BRK13
Break Character Generation Length — BRK13 is used to select a longer transmitted break character length.
Detection of a framing error is not affected by the state of this bit.
0 Break character is transmitted with length of 10 bit times (11 if M = 1)
1 Break character is transmitted with length of 13 bit times (14 if M = 1)
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Table 11-6. SCIxS2 Field Descriptions (continued)
Field
1
LBKDE
0
RAF
1
Description
LIN Break Detection Enable— LBKDE is used to select a longer break character detection length. While
LBKDE is set, framing error (FE) and receive data register full (RDRF) flags are prevented from setting.
0 Break character is detected at length of 10 bit times (11 if M = 1).
1 Break character is detected at length of 11 bit times (12 if M = 1).
Receiver Active Flag — RAF is set when the SCI receiver detects the beginning of a valid start bit, and RAF is
cleared automatically when the receiver detects an idle line. This status flag can be used to check whether an
SCI character is being received before instructing the MCU to go to stop mode.
0 SCI receiver idle waiting for a start bit.
1 SCI receiver active (RxD input not idle).
Setting RXINV inverts the RxD input for all cases: data bits, start and stop bits, break, and idle.
When using an internal oscillator in a LIN system, it is necessary to raise the break detection threshold by
one bit time. Under the worst case timing conditions allowed in LIN, it is possible that a 0x00 data
character can appear to be 10.26 bit times long at a slave which is running 14% faster than the master. This
would trigger normal break detection circuitry which is designed to detect a 10 bit break symbol. When
the LBKDE bit is set, framing errors are inhibited and the break detection threshold changes from 10 bits
to 11 bits, preventing false detection of a 0x00 data character as a LIN break symbol.
11.2.6
SCI Control Register 3 (SCIxC3)
7
R
6
5
4
3
2
1
0
T8
TXDIR
TXINV
ORIE
NEIE
FEIE
PEIE
0
0
0
0
0
0
0
R8
W
Reset
0
= Unimplemented or Reserved
Figure 11-10. SCI Control Register 3 (SCIxC3)
Table 11-7. SCIxC3 Field Descriptions
Field
Description
7
R8
Ninth Data Bit for Receiver — When the SCI is configured for 9-bit data (M = 1), R8 can be thought of as a
ninth receive data bit to the left of the MSB of the buffered data in the SCIxD register. When reading 9-bit data,
read R8 before reading SCIxD because reading SCIxD completes automatic flag clearing sequences which
could allow R8 and SCIxD to be overwritten with new data.
6
T8
Ninth Data Bit for Transmitter — When the SCI is configured for 9-bit data (M = 1), T8 may be thought of as a
ninth transmit data bit to the left of the MSB of the data in the SCIxD register. When writing 9-bit data, the entire
9-bit value is transferred to the SCI shift register after SCIxD is written so T8 should be written (if it needs to
change from its previous value) before SCIxD is written. If T8 does not need to change in the new value (such
as when it is used to generate mark or space parity), it need not be written each time SCIxD is written.
5
TXDIR
TxD Pin Direction in Single-Wire Mode — When the SCI is configured for single-wire half-duplex operation
(LOOPS = RSRC = 1), this bit determines the direction of data at the TxD pin.
0 TxD pin is an input in single-wire mode.
1 TxD pin is an output in single-wire mode.
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Table 11-7. SCIxC3 Field Descriptions (continued)
Field
4
TXINV1
1
Description
Transmit Data Inversion — Setting this bit reverses the polarity of the transmitted data output.
0 Transmit data not inverted
1 Transmit data inverted
3
ORIE
Overrun Interrupt Enable — This bit enables the overrun flag (OR) to generate hardware interrupt requests.
0 OR interrupts disabled (use polling).
1 Hardware interrupt requested when OR = 1.
2
NEIE
Noise Error Interrupt Enable — This bit enables the noise flag (NF) to generate hardware interrupt requests.
0 NF interrupts disabled (use polling).
1 Hardware interrupt requested when NF = 1.
1
FEIE
Framing Error Interrupt Enable — This bit enables the framing error flag (FE) to generate hardware interrupt
requests.
0 FE interrupts disabled (use polling).
1 Hardware interrupt requested when FE = 1.
0
PEIE
Parity Error Interrupt Enable — This bit enables the parity error flag (PF) to generate hardware interrupt
requests.
0 PF interrupts disabled (use polling).
1 Hardware interrupt requested when PF = 1.
Setting TXINV inverts the TxD output for all cases: data bits, start and stop bits, break, and idle.
11.2.7
SCI Data Register (SCIxD)
This register is actually two separate registers. Reads return the contents of the read-only receive data
buffer and writes go to the write-only transmit data buffer. Reads and writes of this register are also
involved in the automatic flag clearing mechanisms for the SCI status flags.
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 11-11. SCI Data Register (SCIxD)
11.3
Functional Description
The SCI allows full-duplex, asynchronous, NRZ serial communication among the MCU and remote
devices, including other MCUs. The SCI comprises a baud rate generator, transmitter, and receiver block.
The transmitter and receiver operate independently, although they use the same baud rate generator. During
normal operation, the MCU monitors the status of the SCI, writes the data to be transmitted, and processes
received data. The following describes each of the blocks of the SCI.
11.3.1
Baud Rate Generation
As shown in Figure 11-12, the clock source for the SCI baud rate generator is the bus-rate clock.
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MODULO DIVIDE BY
(1 THROUGH 8191)
BUSCLK
SBR12:SBR0
BAUD RATE GENERATOR
OFF IF [SBR12:SBR0] = 0
DIVIDE BY
16
Tx BAUD RATE
Rx SAMPLING CLOCK
(16 × BAUD RATE)
BAUD RATE =
BUSCLK
[SBR12:SBR0] × 16
Figure 11-12. SCI Baud Rate Generation
SCI communications require the transmitter and receiver (which typically derive baud rates from
independent clock sources) to use the same baud rate. Allowed tolerance on this baud frequency depends
on the details of how the receiver synchronizes to the leading edge of the start bit and how bit sampling is
performed.
The MCU resynchronizes to bit boundaries on every high-to-low transition, but in the worst case, there are
no such transitions in the full 10- or 11-bit time character frame so any mismatch in baud rate is
accumulated for the whole character time. For a Freescale Semiconductor SCI system whose bus
frequency is driven by a crystal, the allowed baud rate mismatch is about 4.5percent for 8-bit data format
and about 4 percent for 9-bit data format. Although baud rate modulo divider settings do not always
produce baud rates that exactly match standard rates, it is normally possible to get within a few percent,
which is acceptable for reliable communications.
11.3.2
Transmitter Functional Description
This section describes the overall block diagram for the SCI transmitter, as well as specialized functions
for sending break and idle characters. The transmitter block diagram is shown in Figure 11-2.
The transmitter output (TxD) idle state defaults to logic high (TXINV = 0 following reset). The transmitter
output is inverted by setting TXINV = 1. The transmitter is enabled by setting the TE bit in SCIxC2. This
queues a preamble character that is one full character frame of the idle state. The transmitter then remains
idle until data is available in the transmit data buffer. Programs store data into the transmit data buffer by
writing to the SCI data register (SCIxD).
The central element of the SCI transmitter is the transmit shift register that is either 10 or 11 bits long
depending on the setting in the M control bit. For the remainder of this section, we will assume M = 0,
selecting the normal 8-bit data mode. In 8-bit data mode, the shift register holds a start bit, eight data bits,
and a stop bit. When the transmit shift register is available for a new SCI character, the value waiting in
the transmit data register is transferred to the shift register (synchronized with the baud rate clock) and the
transmit data register empty (TDRE) status flag is set to indicate another character may be written to the
transmit data buffer at SCIxD.
If no new character is waiting in the transmit data buffer after a stop bit is shifted out the TxD pin, the
transmitter sets the transmit complete flag and enters an idle mode, with TxD high, waiting for more
characters to transmit.
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Writing 0 to TE does not immediately release the pin to be a general-purpose I/O pin. Any transmit activity
that is in progress must first be completed. This includes data characters in progress, queued idle
characters, and queued break characters.
11.3.2.1
Send Break and Queued Idle
The SBK control bit in SCIxC2 is used to send break characters which were originally used to gain the
attention of old teletype receivers. Break characters are a full character time of logic 0 (10 bit times
including the start and stop bits). A longer break of 13 bit times can be enabled by setting BRK13 = 1.
Normally, a program would wait for TDRE to become set to indicate the last character of a message has
moved to the transmit shifter, then write 1 and then write 0 to the SBK bit. This action queues a break
character to be sent as soon as the shifter is available. If SBK is still 1 when the queued break moves into
the shifter (synchronized to the baud rate clock), an additional break character is queued. If the receiving
device is another Freescale Semiconductor SCI, the break characters will be received as 0s in all eight data
bits and a framing error (FE = 1) occurs.
When idle-line wakeup is used, a full character time of idle (logic 1) is needed between messages to wake
up any sleeping receivers. Normally, a program would wait for TDRE to become set to indicate the last
character of a message has moved to the transmit shifter, then write 0 and then write 1 to the TE bit. This
action queues an idle character to be sent as soon as the shifter is available. As long as the character in the
shifter does not finish while TE = 0, the SCI transmitter never actually releases control of the TxD pin. If
there is a possibility of the shifter finishing while TE = 0, set the general-purpose I/O controls so the pin
that is shared with TxD is an output driving a logic 1. This ensures that the TxD line will look like a normal
idle line even if the SCI loses control of the port pin between writing 0 and then 1 to TE.
The length of the break character is affected by the BRK13 and M bits as shown below.
Table 11-8. Break Character Length
11.3.3
BRK13
M
Break Character Length
0
0
10 bit times
0
1
11 bit times
1
0
13 bit times
1
1
14 bit times
Receiver Functional Description
In this section, the receiver block diagram (Figure 11-3) is used as a guide for the overall receiver
functional description. Next, the data sampling technique used to reconstruct receiver data is described in
more detail. Finally, two variations of the receiver wakeup function are explained.
The receiver input is inverted by setting RXINV = 1. The receiver is enabled by setting the RE bit in
SCIxC2. Character frames consist of a start bit of logic 0, eight (or nine) data bits (LSB first), and a stop
bit of logic 1. For information about 9-bit data mode, refer to Section 11.3.5.1, “8- and 9-Bit Data Modes.”
For the remainder of this discussion, we assume the SCI is configured for normal 8-bit data mode.
After receiving the stop bit into the receive shifter, and provided the receive data register is not already full,
the data character is transferred to the receive data register and the receive data register full (RDRF) status
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flag is set. If RDRF was already set indicating the receive data register (buffer) was already full, the overrun
(OR) status flag is set and the new data is lost. Because the SCI receiver is double-buffered, the program
has one full character time after RDRF is set before the data in the receive data buffer must be read to avoid
a receiver overrun.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCIxD. The RDRF flag is cleared automatically by a 2-step sequence which is
normally satisfied in the course of the user’s program that handles receive data. Refer to Section 11.3.4,
“Interrupts and Status Flags” for more details about flag clearing.
11.3.3.1
Data Sampling Technique
The SCI receiver uses a 16× baud rate clock for sampling. The receiver starts by taking logic level samples
at 16 times the baud rate to search for a falling edge on the RxD serial data input pin. A falling edge is
defined as a logic 0 sample after three consecutive logic 1 samples. The 16× baud rate clock is used to
divide the bit time into 16 segments labeled RT1 through RT16. When a falling edge is located, three more
samples are taken at RT3, RT5, and RT7 to make sure this was a real start bit and not merely noise. If at
least two of these three samples are 0, the receiver assumes it is synchronized to a receive character.
The receiver then samples each bit time, including the start and stop bits, at RT8, RT9, and RT10 to
determine the logic level for that bit. The logic level is interpreted to be that of the majority of the samples
taken during the bit time. In the case of the start bit, the bit is assumed to be 0 if at least two of the samples
at RT3, RT5, and RT7 are 0 even if one or all of the samples taken at RT8, RT9, and RT10 are 1s. If any
sample in any bit time (including the start and stop bits) in a character frame fails to agree with the logic
level for that bit, the noise flag (NF) will be set when the received character is transferred to the receive
data buffer.
The falling edge detection logic continuously looks for falling edges, and if an edge is detected, the sample
clock is resynchronized to bit times. This improves the reliability of the receiver in the presence of noise
or mismatched baud rates. It does not improve worst case analysis because some characters do not have
any extra falling edges anywhere in the character frame.
In the case of a framing error, provided the received character was not a break character, the sampling logic
that searches for a falling edge is filled with three logic 1 samples so that a new start bit can be detected
almost immediately.
In the case of a framing error, the receiver is inhibited from receiving any new characters until the framing
error flag is cleared. The receive shift register continues to function, but a complete character cannot
transfer to the receive data buffer if FE is still set.
11.3.3.2
Receiver Wakeup Operation
Receiver wakeup is a hardware mechanism that allows an SCI receiver to ignore the characters in a
message that is intended for a different SCI receiver. In such a system, all receivers evaluate the first
character(s) of each message, and as soon as they determine the message is intended for a different
receiver, they write logic 1 to the receiver wake up (RWU) control bit in SCIxC2. When RWU bit is set,
the status flags associated with the receiver (with the exception of the idle bit, IDLE, when RWUID bit is
set) are inhibited from setting, thus eliminating the software overhead for handling the unimportant
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message characters. At the end of a message, or at the beginning of the next message, all receivers
automatically force RWU to 0 so all receivers wake up in time to look at the first character(s) of the next
message.
11.3.3.2.1
Idle-Line Wakeup
When WAKE = 0, the receiver is configured for idle-line wakeup. In this mode, RWU is cleared
automatically when the receiver detects a full character time of the idle-line level. The M control bit selects
8-bit or 9-bit data mode that determines how many bit times of idle are needed to constitute a full character
time (10 or 11 bit times because of the start and stop bits).
When RWU is one and RWUID is zero, the idle condition that wakes up the receiver does not set the IDLE
flag. The receiver wakes up and waits for the first data character of the next message which will set the
RDRF flag and generate an interrupt if enabled. When RWUID is one, any idle condition sets the IDLE
flag and generates an interrupt if enabled, regardless of whether RWU is zero or one.
The idle-line type (ILT) control bit selects one of two ways to detect an idle line. When ILT = 0, the idle
bit counter starts after the start bit so the stop bit and any logic 1s at the end of a character count toward
the full character time of idle. When ILT = 1, the idle bit counter does not start until after a stop bit time,
so the idle detection is not affected by the data in the last character of the previous message.
11.3.3.2.2
Address-Mark Wakeup
When WAKE = 1, the receiver is configured for address-mark wakeup. In this mode, RWU is cleared
automatically when the receiver detects a logic 1 in the most significant bit of a received character (eighth
bit in M = 0 mode and ninth bit in M = 1 mode).
Address-mark wakeup allows messages to contain idle characters but requires that the MSB be reserved
for use in address frames. The logic 1 MSB of an address frame clears the RWU bit before the stop bit is
received and sets the RDRF flag. In this case the character with the MSB set is received even though the
receiver was sleeping during most of this character time.
11.3.4
Interrupts and Status Flags
The SCI system has three separate interrupt vectors to reduce the amount of software needed to isolate the
cause of the interrupt. One interrupt vector is associated with the transmitter for TDRE and TC events.
Another interrupt vector is associated with the receiver for RDRF, IDLE, RXEDGIF and LBKDIF events,
and a third vector is used for OR, NF, FE, and PF error conditions. Each of these ten interrupt sources can
be separately masked by local interrupt enable masks. The flags can still be polled by software when the
local masks are cleared to disable generation of hardware interrupt requests.
The SCI transmitter has two status flags that optionally can generate hardware interrupt requests. Transmit
data register empty (TDRE) indicates when there is room in the transmit data buffer to write another
transmit character to SCIxD. If the transmit interrupt enable (TIE) bit is set, a hardware interrupt will be
requested whenever TDRE = 1. Transmit complete (TC) indicates that the transmitter is finished
transmitting all data, preamble, and break characters and is idle with TxD at the inactive level. This flag is
often used in systems with modems to determine when it is safe to turn off the modem. If the transmit
complete interrupt enable (TCIE) bit is set, a hardware interrupt will be requested whenever TC = 1.
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Instead of hardware interrupts, software polling may be used to monitor the TDRE and TC status flags if
the corresponding TIE or TCIE local interrupt masks are 0s.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCIxD. The RDRF flag is cleared by reading SCIxS1 while RDRF = 1 and then
reading SCIxD.
When polling is used, this sequence is naturally satisfied in the normal course of the user program. If
hardware interrupts are used, SCIxS1 must be read in the interrupt service routine (ISR). Normally, this is
done in the ISR anyway to check for receive errors, so the sequence is automatically satisfied.
The IDLE status flag includes logic that prevents it from getting set repeatedly when the RxD line remains
idle for an extended period of time. IDLE is cleared by reading SCIxS1 while IDLE = 1 and then reading
SCIxD. After IDLE has been cleared, it cannot become set again until the receiver has received at least one
new character and has set RDRF.
If the associated error was detected in the received character that caused RDRF to be set, the error flags —
noise flag (NF), framing error (FE), and parity error flag (PF) — get set at the same time as RDRF. These
flags are not set in overrun cases.
If RDRF was already set when a new character is ready to be transferred from the receive shifter to the
receive data buffer, the overrun (OR) flag gets set instead the data along with any associated NF, FE, or PF
condition is lost.
At any time, an active edge on the RxD serial data input pin causes the RXEDGIF flag to set. The
RXEDGIF flag is cleared by writing a “1” to it. This function does depend on the receiver being enabled
(RE = 1).
11.3.5
Additional SCI Functions
The following sections describe additional SCI functions.
11.3.5.1
8- and 9-Bit Data Modes
The SCI system (transmitter and receiver) can be configured to operate in 9-bit data mode by setting the
M control bit in SCIxC1. In 9-bit mode, there is a ninth data bit to the left of the MSB of the SCI data
register. For the transmit data buffer, this bit is stored in T8 in SCIxC3. For the receiver, the ninth bit is
held in R8 in SCIxC3.
For coherent writes to the transmit data buffer, write to the T8 bit before writing to SCIxD.
If the bit value to be transmitted as the ninth bit of a new character is the same as for the previous character,
it is not necessary to write to T8 again. When data is transferred from the transmit data buffer to the
transmit shifter, the value in T8 is copied at the same time data is transferred from SCIxD to the shifter.
9-bit data mode typically is used in conjunction with parity to allow eight bits of data plus the parity in the
ninth bit. Or it is used with address-mark wakeup so the ninth data bit can serve as the wakeup bit. In
custom protocols, the ninth bit can also serve as a software-controlled marker.
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11.3.5.2
Stop Mode Operation
During all stop modes, clocks to the SCI module are halted.
In stop1 and stop2 modes, all SCI register data is lost and must be re-initialized upon recovery from these
two stop modes. No SCI module registers are affected in stop3 mode.
The receive input active edge detect circuit is still active in stop3 mode, but not in stop2. . An active edge
on the receive input brings the CPU out of stop3 mode if the interrupt is not masked (RXEDGIE = 1).
Note, because the clocks are halted, the SCI module will resume operation upon exit from stop (only in
stop3 mode). Software should ensure stop mode is not entered while there is a character being transmitted
out of or received into the SCI module.
11.3.5.3
Loop Mode
When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or
single-wire mode (RSRC = 1). Loop mode is sometimes used to check software, independent of
connections in the external system, to help isolate system problems. In this mode, the transmitter output is
internally connected to the receiver input and the RxD pin is not used by the SCI, so it reverts to a
general-purpose port I/O pin.
11.3.5.4
Single-Wire Operation
When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or
single-wire mode (RSRC = 1). Single-wire mode is used to implement a half-duplex serial connection.
The receiver is internally connected to the transmitter output and to the TxD pin. The RxD pin is not used
and reverts to a general-purpose port I/O pin.
In single-wire mode, the TXDIR bit in SCIxC3 controls the direction of serial data on the TxD pin. When
TXDIR = 0, the TxD pin is an input to the SCI receiver and the transmitter is temporarily disconnected
from the TxD pin so an external device can send serial data to the receiver. When TXDIR = 1, the TxD pin
is an output driven by the transmitter. In single-wire mode, the internal loop back connection from the
transmitter to the receiver causes the receiver to receive characters that are sent out by the transmitter.
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Freescale Semiconductor
Chapter 12
Serial Peripheral Interface (S08SPIV3)
12.1
Introduction
The MC9S08AC16 Series has one serial peripheral interface (SPI) module. The four pins associated with
SPI functionality are shared with port E pins 4–7. See Appendix A, “Electrical Characteristics and Timing
Specifications,” for SPI electrical parametric information.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
213
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 12 Serial Peripheral Interface (S08SPIV3)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 12-1. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 12 Serial Peripheral Interface (S08SPIV3)
12.1.1
Features
Features of the SPI module include:
• Master or slave mode operation
• Full-duplex or single-wire bidirectional option
• Programmable transmit bit rate
• Double-buffered transmit and receive
• Serial clock phase and polarity options
• Slave select output
• Selectable MSB-first or LSB-first shifting
12.1.2
Block Diagrams
This section includes block diagrams showing SPI system connections, the internal organization of the SPI
module, and the SPI clock dividers that control the master mode bit rate.
12.1.2.1
SPI System Block Diagram
Figure 12-2 shows the SPI modules of two MCUs connected in a master-slave arrangement. The master
device initiates all SPI data transfers. During a transfer, the master shifts data out (on the MOSI pin) to the
slave while simultaneously shifting data in (on the MISO pin) from the slave. The transfer effectively
exchanges the data that was in the SPI shift registers of the two SPI systems. The SPSCK signal is a clock
output from the master and an input to the slave. The slave device must be selected by a low level on the
slave select input (SS pin). In this system, the master device has configured its SS pin as an optional slave
select output.
SLAVE
MASTER
MOSI
MOSI
SPI SHIFTER
7
6
5
4
3
2
SPI SHIFTER
1
0
MISO
SPSCK
CLOCK
GENERATOR
SS
MISO
7
6
5
4
3
2
1
0
SPSCK
SS
Figure 12-2. SPI System Connections
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Chapter 12 Serial Peripheral Interface (S08SPIV3)
The most common uses of the SPI system include connecting simple shift registers for adding input or
output ports or connecting small peripheral devices such as serial A/D or D/A converters. Although
Figure 12-2 shows a system where data is exchanged between two MCUs, many practical systems involve
simpler connections where data is unidirectionally transferred from the master MCU to a slave or from a
slave to the master MCU.
12.1.2.2
SPI Module Block Diagram
Figure 12-3 is a block diagram of the SPI module. The central element of the SPI is the SPI shift register.
Data is written to the double-buffered transmitter (write to SPI1D) and gets transferred to the SPI shift
register at the start of a data transfer. After shifting in a byte of data, the data is transferred into the
double-buffered receiver where it can be read (read from SPI1D). Pin multiplexing logic controls
connections between MCU pins and the SPI module.
When the SPI is configured as a master, the clock output is routed to the SPSCK pin, the shifter output is
routed to MOSI, and the shifter input is routed from the MISO pin.
When the SPI is configured as a slave, the SPSCK pin is routed to the clock input of the SPI, the shifter
output is routed to MISO, and the shifter input is routed from the MOSI pin.
In the external SPI system, simply connect all SPSCK pins to each other, all MISO pins together, and all
MOSI pins together. Peripheral devices often use slightly different names for these pins.
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Chapter 12 Serial Peripheral Interface (S08SPIV3)
PIN CONTROL
M
SPE
MOSI
(MOMI)
S
Tx BUFFER (WRITE SPI1D)
ENABLE
SPI SYSTEM
M
SHIFT
OUT
SPI SHIFT REGISTER
SHIFT
IN
MISO
(SISO)
S
SPC0
Rx BUFFER (READ SPI1D)
BIDIROE
SHIFT
DIRECTION
LSBFE
SHIFT
CLOCK
Rx BUFFER
FULL
Tx BUFFER
EMPTY
MASTER CLOCK
BUS RATE
CLOCK
SPIBR
CLOCK GENERATOR
MSTR
CLOCK
LOGIC
SLAVE CLOCK
MASTER/SLAVE
M
SPSCK
S
MASTER/
SLAVE
MODE SELECT
MODFEN
SSOE
MODE FAULT
DETECTION
SS
SPTEF
SPRF
SPTIE
MODF
SPIE
SPI
INTERRUPT
REQUEST
Figure 12-3. SPI Module Block Diagram
12.1.3
SPI Baud Rate Generation
As shown in Figure 12-4, the clock source for the SPI baud rate generator is the bus clock. The three
prescale bits (SPPR2:SPPR1:SPPR0) choose a prescale divisor of 1, 2, 3, 4, 5, 6, 7, or 8. The three rate
select bits (SPR2:SPR1:SPR0) divide the output of the prescaler stage by 2, 4, 8, 16, 32, 64, 128, or 256
to get the internal SPI master mode bit-rate clock.
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BUS CLOCK
PRESCALER
CLOCK RATE DIVIDER
DIVIDE BY
1, 2, 3, 4, 5, 6, 7, or 8
DIVIDE BY
2, 4, 8, 16, 32, 64, 128, or 256
SPPR2:SPPR1:SPPR0
SPR2:SPR1:SPR0
MASTER
SPI
BIT RATE
Figure 12-4. SPI Baud Rate Generation
12.2
External Signal Description
The SPI optionally shares four port pins. The function of these pins depends on the settings of SPI control
bits. When the SPI is disabled (SPE = 0), these four pins revert to being general-purpose port I/O pins that
are not controlled by the SPI.
12.2.1
SPSCK — SPI Serial Clock
When the SPI is enabled as a slave, this pin is the serial clock input. When the SPI is enabled as a master,
this pin is the serial clock output.
12.2.2
MOSI — Master Data Out, Slave Data In
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this
pin is the serial data output. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data
input. If SPC0 = 1 to select single-wire bidirectional mode, and master mode is selected, this pin becomes
the bidirectional data I/O pin (MOMI). Also, the bidirectional mode output enable bit determines whether
the pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and slave mode is
selected, this pin is not used by the SPI and reverts to being a general-purpose port I/O pin.
12.2.3
MISO — Master Data In, Slave Data Out
When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this
pin is the serial data input. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data
output. If SPC0 = 1 to select single-wire bidirectional mode, and slave mode is selected, this pin becomes
the bidirectional data I/O pin (SISO) and the bidirectional mode output enable bit determines whether the
pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and master mode is selected,
this pin is not used by the SPI and reverts to being a general-purpose port I/O pin.
12.2.4
SS — Slave Select
When the SPI is enabled as a slave, this pin is the low-true slave select input. When the SPI is enabled as
a master and mode fault enable is off (MODFEN = 0), this pin is not used by the SPI and reverts to being
a general-purpose port I/O pin. When the SPI is enabled as a master and MODFEN = 1, the slave select
output enable bit determines whether this pin acts as the mode fault input (SSOE = 0) or as the slave select
output (SSOE = 1).
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12.3
Modes of Operation
12.3.1
SPI in Stop Modes
The SPI is disabled in all stop modes, regardless of the settings before executing the STOP instruction.
During either stop1 or stop2 mode, the SPI module will be fully powered down. Upon wake-up from stop1
or stop2 mode, the SPI module will be in the reset state. During stop3 mode, clocks to the SPI module are
halted. No registers are affected. If stop3 is exited with a reset, the SPI will be put into its reset state. If
stop3 is exited with an interrupt, the SPI continues from the state it was in when stop3 was entered.
12.4
Register Definition
The SPI has five 8-bit registers to select SPI options, control baud rate, report SPI status, and for
transmit/receive data.
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all SPI registers. This section refers to registers and control bits only by their names, and
a Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
12.4.1
SPI Control Register 1 (SPI1C1)
This read/write register includes the SPI enable control, interrupt enables, and configuration options.
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 12-5. SPI Control Register 1 (SPI1C1)
Table 12-1. SPI1C1 Field Descriptions
Field
Description
7
SPIE
SPI Interrupt Enable (for SPRF and MODF) — This is the interrupt enable for SPI receive buffer full (SPRF)
and mode fault (MODF) events.
0 Interrupts from SPRF and MODF inhibited (use polling)
1 When SPRF or MODF is 1, request a hardware interrupt
6
SPE
SPI System Enable — Disabling the SPI halts any transfer that is in progress, clears data buffers, and initializes
internal state machines. SPRF is cleared and SPTEF is set to indicate the SPI transmit data buffer is empty.
0 SPI system inactive
1 SPI system enabled
5
SPTIE
SPI Transmit Interrupt Enable — This is the interrupt enable bit for SPI transmit buffer empty (SPTEF).
0 Interrupts from SPTEF inhibited (use polling)
1 When SPTEF is 1, hardware interrupt requested
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Table 12-1. SPI1C1 Field Descriptions (continued)
Field
Description
4
MSTR
Master/Slave Mode Select
0 SPI module configured as a slave SPI device
1 SPI module configured as a master SPI device
3
CPOL
Clock Polarity — This bit effectively places an inverter in series with the clock signal from a master SPI or to a
slave SPI device. Refer to Section 12.5.1, “SPI Clock Formats” for more details.
0 Active-high SPI clock (idles low)
1 Active-low SPI clock (idles high)
2
CPHA
Clock Phase — This bit selects one of two clock formats for different kinds of synchronous serial peripheral
devices. Refer to Section 12.5.1, “SPI Clock Formats” for more details.
0 First edge on SPSCK occurs at the middle of the first cycle of an 8-cycle data transfer
1 First edge on SPSCK occurs at the start of the first cycle of an 8-cycle data transfer
1
SSOE
Slave Select Output Enable — This bit is used in combination with the mode fault enable (MODFEN) bit in
SPCR2 and the master/slave (MSTR) control bit to determine the function of the SS pin as shown in Table 12-2.
0
LSBFE
LSB First (Shifter Direction)
0 SPI serial data transfers start with most significant bit
1 SPI serial data transfers start with least significant bit
Table 12-2. SS Pin Function
MODFEN
SSOE
Master Mode
Slave Mode
0
0
General-purpose I/O (not SPI)
Slave select input
0
1
General-purpose I/O (not SPI)
Slave select input
1
0
SS input for mode fault
Slave select input
1
1
Automatic SS output
Slave select input
NOTE
Ensure that the SPI should not be disabled (SPE=0) at the same time as a bit change to the CPHA bit. These
changes should be performed as separate operations or unexpected behavior may occur.
12.4.2
SPI Control Register 2 (SPI1C2)
This read/write register is used to control optional features of the SPI system. Bits 7, 6, 5, and 2 are not
implemented and always read 0.
R
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 12-6. SPI Control Register 2 (SPI1C2)
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Table 12-3. SPI1C2 Register Field Descriptions
Field
Description
4
MODFEN
Master Mode-Fault Function Enable — When the SPI is configured for slave mode, this bit has no meaning or
effect. (The SS pin is the slave select input.) In master mode, this bit determines how the SS pin is used (refer
to Table 12-2 for more details).
0 Mode fault function disabled, master SS pin reverts to general-purpose I/O not controlled by SPI
1 Mode fault function enabled, master SS pin acts as the mode fault input or the slave select output
3
BIDIROE
Bidirectional Mode Output Enable — When bidirectional mode is enabled by SPI pin control 0 (SPC0) = 1,
BIDIROE determines whether the SPI data output driver is enabled to the single bidirectional SPI I/O pin.
Depending on whether the SPI is configured as a master or a slave, it uses either the MOSI (MOMI) or MISO
(SISO) pin, respectively, as the single SPI data I/O pin. When SPC0 = 0, BIDIROE has no meaning or effect.
0 Output driver disabled so SPI data I/O pin acts as an input
1 SPI I/O pin enabled as an output
1
SPISWAI
SPI Stop in Wait Mode
0 SPI clocks continue to operate in wait mode
1 SPI clocks stop when the MCU enters wait mode
0
SPC0
12.4.3
SPI Pin Control 0 — The SPC0 bit chooses single-wire bidirectional mode. If MSTR = 0 (slave mode), the SPI
uses the MISO (SISO) pin for bidirectional SPI data transfers. If MSTR = 1 (master mode), the SPI uses the
MOSI (MOMI) pin for bidirectional SPI data transfers. When SPC0 = 1, BIDIROE is used to enable or disable the
output driver for the single bidirectional SPI I/O pin.
0 SPI uses separate pins for data input and data output
1 SPI configured for single-wire bidirectional operation
SPI Baud Rate Register (SPI1BR)
This register is used to set the prescaler and bit rate divisor for an SPI master. This register may be read or
written at any time.
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 12-7. SPI Baud Rate Register (SPI1BR)
Table 12-4. SPI1BR Register Field Descriptions
Field
Description
6:4
SPPR[2:0]
SPI Baud Rate Prescale Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate prescaler
as shown in Table 12-5. The input to this prescaler is the bus rate clock (BUSCLK). The output of this prescaler
drives the input of the SPI baud rate divider (see Figure 12-4).
2:0
SPR[2:0]
SPI Baud Rate Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate divider as shown in
Table 12-6. The input to this divider comes from the SPI baud rate prescaler (see Figure 12-4). The output of this
divider is the SPI bit rate clock for master mode.
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Table 12-5. SPI Baud Rate Prescaler Divisor
SPPR2:SPPR1:SPPR0
Prescaler Divisor
0:0:0
1
0:0:1
2
0:1:0
3
0:1:1
4
1:0:0
5
1:0:1
6
1:1:0
7
1:1:1
8
Table 12-6. SPI Baud Rate Divisor
12.4.4
SPR2:SPR1:SPR0
Rate Divisor
0:0:0
2
0:0:1
4
0:1:0
8
0:1:1
16
1:0:0
32
1:0:1
64
1:1:0
128
1:1:1
256
SPI Status Register (SPI1S)
This register has three read-only status bits. Bits 6, 3, 2, 1, and 0 are not implemented and always read 0.
Writes have no meaning or effect.
R
7
6
5
4
3
2
1
0
SPRF
0
SPTEF
MODF
0
0
0
0
0
0
1
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 12-8. SPI Status Register (SPI1S)
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Table 12-7. SPI1S Register Field Descriptions
Field
Description
7
SPRF
SPI Read Buffer Full Flag — SPRF is set at the completion of an SPI transfer to indicate that received data may
be read from the SPI data register (SPI1D). SPRF is cleared by reading SPRF while it is set, then reading the
SPI data register.
0 No data available in the receive data buffer
1 Data available in the receive data buffer
5
SPTEF
SPI Transmit Buffer Empty Flag — This bit is set when there is room in the transmit data buffer. It is cleared by
reading SPI1S with SPTEF set, followed by writing a data value to the transmit buffer at SPI1D. SPI1S must be
read with SPTEF = 1 before writing data to SPI1D or the SPI1D write will be ignored. SPTEF generates an
SPTEF CPU interrupt request if the SPTIE bit in the SPI1C1 is also set. SPTEF is automatically set when a data
byte transfers from the transmit buffer into the transmit shift register. For an idle SPI (no data in the transmit buffer
or the shift register and no transfer in progress), data written to SPI1D is transferred to the shifter almost
immediately so SPTEF is set within two bus cycles allowing a second 8-bit data value to be queued into the
transmit buffer. After completion of the transfer of the value in the shift register, the queued value from the
transmit buffer will automatically move to the shifter and SPTEF will be set to indicate there is room for new data
in the transmit buffer. If no new data is waiting in the transmit buffer, SPTEF simply remains set and no data
moves from the buffer to the shifter.
0 SPI transmit buffer not empty
1 SPI transmit buffer empty
4
MODF
Master Mode Fault Flag — MODF is set if the SPI is configured as a master and the slave select input goes
low, indicating some other SPI device is also configured as a master. The SS pin acts as a mode fault error input
only when MSTR = 1, MODFEN = 1, and SSOE = 0; otherwise, MODF will never be set. MODF is cleared by
reading MODF while it is 1, then writing to SPI control register 1 (SPI1C1).
0 No mode fault error
1 Mode fault error detected
12.4.5
SPI Data Register (SPI1D)
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 12-9. SPI Data Register (SPI1D)
Reads of this register return the data read from the receive data buffer. Writes to this register write data to
the transmit data buffer. When the SPI is configured as a master, writing data to the transmit data buffer
initiates an SPI transfer.
Data should not be written to the transmit data buffer unless the SPI transmit buffer empty flag (SPTEF)
is set, indicating there is room in the transmit buffer to queue a new transmit byte.
Data may be read from SPI1D any time after SPRF is set and before another transfer is finished. Failure
to read the data out of the receive data buffer before a new transfer ends causes a receive overrun condition
and the data from the new transfer is lost.
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12.5
Functional Description
An SPI transfer is initiated by checking for the SPI transmit buffer empty flag (SPTEF = 1) and then
writing a byte of data to the SPI data register (SPI1D) in the master SPI device. When the SPI shift register
is available, this byte of data is moved from the transmit data buffer to the shifter, SPTEF is set to indicate
there is room in the buffer to queue another transmit character if desired, and the SPI serial transfer starts.
During the SPI transfer, data is sampled (read) on the MISO pin at one SPSCK edge and shifted, changing
the bit value on the MOSI pin, one-half SPSCK cycle later. After eight SPSCK cycles, the data that was in
the shift register of the master has been shifted out the MOSI pin to the slave while eight bits of data were
shifted in the MISO pin into the master’s shift register. At the end of this transfer, the received data byte is
moved from the shifter into the receive data buffer and SPRF is set to indicate the data can be read by
reading SPI1D. If another byte of data is waiting in the transmit buffer at the end of a transfer, it is moved
into the shifter, SPTEF is set, and a new transfer is started.
Normally, SPI data is transferred most significant bit (MSB) first. If the least significant bit first enable
(LSBFE) bit is set, SPI data is shifted LSB first.
When the SPI is configured as a slave, its SS pin must be driven low before a transfer starts and SS must
stay low throughout the transfer. If a clock format where CPHA = 0 is selected, SS must be driven to a
logic 1 between successive transfers. If CPHA = 1, SS may remain low between successive transfers. See
Section 12.5.1, “SPI Clock Formats” for more details.
Because the transmitter and receiver are double buffered, a second byte, in addition to the byte currently
being shifted out, can be queued into the transmit data buffer, and a previously received character can be
in the receive data buffer while a new character is being shifted in. The SPTEF flag indicates when the
transmit buffer has room for a new character. The SPRF flag indicates when a received character is
available in the receive data buffer. The received character must be read out of the receive buffer (read
SPI1D) before the next transfer is finished or a receive overrun error results.
In the case of a receive overrun, the new data is lost because the receive buffer still held the previous
character and was not ready to accept the new data. There is no indication for such an overrun condition
so the application system designer must ensure that previous data has been read from the receive buffer
before a new transfer is initiated.
12.5.1
SPI Clock Formats
To accommodate a wide variety of synchronous serial peripherals from different manufacturers, the SPI
system has a clock polarity (CPOL) bit and a clock phase (CPHA) control bit to select one of four clock
formats for data transfers. CPOL selectively inserts an inverter in series with the clock. CPHA chooses
between two different clock phase relationships between the clock and data.
Figure 12-10 shows the clock formats when CPHA = 1. At the top of the figure, the eight bit times are
shown for reference with bit 1 starting at the first SPSCK edge and bit 8 ending one-half SPSCK cycle after
the sixteenth SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending
on the setting in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms
applies for a specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the
MOSI input of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output
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pin from a master and the MISO waveform applies to the MISO output from a slave. The SS OUT
waveform applies to the slave select output from a master (provided MODFEN and SSOE = 1). The master
SS output goes to active low one-half SPSCK cycle before the start of the transfer and goes back high at
the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a
slave.
BIT TIME #
(REFERENCE)
1
2
...
6
7
8
BIT 7
BIT 0
BIT 6
BIT 1
...
...
BIT 2
BIT 5
BIT 1
BIT 6
BIT 0
BIT 7
SPSCK
(CPOL = 0)
SPSCK
(CPOL = 1)
SAMPLE IN
(MISO OR MOSI)
MOSI
(MASTER OUT)
MSB FIRST
LSB FIRST
MISO
(SLAVE OUT)
SS OUT
(MASTER)
SS IN
(SLAVE)
Figure 12-10. SPI Clock Formats (CPHA = 1)
When CPHA = 1, the slave begins to drive its MISO output when SS goes to active low, but the data is not
defined until the first SPSCK edge. The first SPSCK edge shifts the first bit of data from the shifter onto
the MOSI output of the master and the MISO output of the slave. The next SPSCK edge causes both the
master and the slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the
third SPSCK edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled,
and shifts the second data bit value out the other end of the shifter to the MOSI and MISO outputs of the
master and slave, respectively. When CHPA = 1, the slave’s SS input is not required to go to its inactive
high level between transfers.
Figure 12-11 shows the clock formats when CPHA = 0. At the top of the figure, the eight bit times are
shown for reference with bit 1 starting as the slave is selected (SS IN goes low), and bit 8 ends at the last
SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending on the setting
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
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Chapter 12 Serial Peripheral Interface (S08SPIV3)
in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms applies for a
specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the MOSI input
of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output pin from a
master and the MISO waveform applies to the MISO output from a slave. The SS OUT waveform applies
to the slave select output from a master (provided MODFEN and SSOE = 1). The master SS output goes
to active low at the start of the first bit time of the transfer and goes back high one-half SPSCK cycle after
the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a
slave.
BIT TIME #
(REFERENCE)
1
2
BIT 7
BIT 0
BIT 6
BIT 1
...
6
7
8
BIT 2
BIT 5
BIT 1
BIT 6
BIT 0
BIT 7
SPSCK
(CPOL = 0)
SPSCK
(CPOL = 1)
SAMPLE IN
(MISO OR MOSI)
MOSI
(MASTER OUT)
MSB FIRST
LSB FIRST
...
...
MISO
(SLAVE OUT)
SS OUT
(MASTER)
SS IN
(SLAVE)
Figure 12-11. SPI Clock Formats (CPHA = 0)
When CPHA = 0, the slave begins to drive its MISO output with the first data bit value (MSB or LSB
depending on LSBFE) when SS goes to active low. The first SPSCK edge causes both the master and the
slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the second SPSCK
edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled and shifts the
second data bit value out the other end of the shifter to the MOSI and MISO outputs of the master and
slave, respectively. When CPHA = 0, the slave’s SS input must go to its inactive high level between
transfers.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 12 Serial Peripheral Interface (S08SPIV3)
12.5.2
SPI Interrupts
There are three flag bits, two interrupt mask bits, and one interrupt vector associated with the SPI system.
The SPI interrupt enable mask (SPIE) enables interrupts from the SPI receiver full flag (SPRF) and mode
fault flag (MODF). The SPI transmit interrupt enable mask (SPTIE) enables interrupts from the SPI
transmit buffer empty flag (SPTEF). When one of the flag bits is set, and the associated interrupt mask bit
is set, a hardware interrupt request is sent to the CPU. If the interrupt mask bits are cleared, software can
poll the associated flag bits instead of using interrupts. The SPI interrupt service routine (ISR) should
check the flag bits to determine what event caused the interrupt. The service routine should also clear the
flag bit(s) before returning from the ISR (usually near the beginning of the ISR).
12.5.3
Mode Fault Detection
A mode fault occurs and the mode fault flag (MODF) becomes set when a master SPI device detects an
error on the SS pin (provided the SS pin is configured as the mode fault input signal). The SS pin is
configured to be the mode fault input signal when MSTR = 1, mode fault enable is set (MODFEN = 1),
and slave select output enable is clear (SSOE = 0).
The mode fault detection feature can be used in a system where more than one SPI device might become
a master at the same time. The error is detected when a master’s SS pin is low, indicating that some other
SPI device is trying to address this master as if it were a slave. This could indicate a harmful output driver
conflict, so the mode fault logic is designed to disable all SPI output drivers when such an error is detected.
When a mode fault is detected, MODF is set and MSTR is cleared to change the SPI configuration back
to slave mode. The output drivers on the SPSCK, MOSI, and MISO (if not bidirectional mode) are
disabled.
MODF is cleared by reading it while it is set, then writing to the SPI control register 1 (SPI1C1). User
software should verify the error condition has been corrected before changing the SPI back to master
mode.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
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Chapter 12 Serial Peripheral Interface (S08SPIV3)
MC9S08AC16 Series Data Sheet, Rev. 0
228
PRELIMINARY
Freescale Semiconductor
Chapter 13
Inter-Integrated Circuit (S08IICV2)
13.1
Introduction
The MC9S08AC16 Series series of microcontrollers has an inter-integrated circuit (IIC) module for
communication with other integrated circuits. The two pins associated with this module, SCL and SDA,
are shared with port C pins 0 and 1, respectively.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
229
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 13 Inter-Integrated Circuit (S08IICV2)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
2 KBIP6–KBIP5
5 KBIP4–KBIP0
PORT D
LVD
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
IRQ
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 13-1. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
230
PRELIMINARY
Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.1.1
Features
The IIC includes these distinctive features:
• Compatible with IIC bus standard
• Multi-master operation
• Software programmable for one of 64 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
• General call recognition
• 10-bit address extension
13.1.2
Modes of Operation
A brief description of the IIC in the various MCU modes is given here.
• Run mode — This is the basic mode of operation. To conserve power in this mode, disable the
module.
• Wait mode — The module continues to operate while the MCU is in wait mode and can provide
a wake-up interrupt.
• Stop mode — The IIC is inactive in stop3 mode for reduced power consumption. The stop
instruction does not affect IIC register states. Stop2 and stop1 resets the register contents.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.1.3
Block Diagram
Figure 13-2 is a block diagram of the IIC.
Address
Data Bus
Interrupt
ADDR_DECODE
CTRL_REG
DATA_MUX
FREQ_REG
ADDR_REG
STATUS_REG
DATA_REG
Input
Sync
Start
Stop
Arbitration
Control
Clock
Control
In/Out
Data
Shift
Register
Address
Compare
SCL
SDA
Figure 13-2. IIC Functional Block Diagram
13.2
External Signal Description
This section describes each user-accessible pin signal.
13.2.1
SCL — Serial Clock Line
The bidirectional SCL is the serial clock line of the IIC system.
13.2.2
SDA — Serial Data Line
The bidirectional SDA is the serial data line of the IIC system.
13.3
Register Definition
This section consists of the IIC register descriptions in address order.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
Refer to the direct-page register summary in the memory chapter of this document for the absolute address
assignments for all IIC registers. This section refers to registers and control bits only by their names. A
Freescale-provided equate or header file is used to translate these names into the appropriate absolute
addresses.
13.3.1
IIC Address Register (IIC1A)
7
6
5
4
3
2
1
AD7
AD6
AD5
AD4
AD3
AD2
AD1
0
0
0
0
0
0
0
R
0
0
W
Reset
0
= Unimplemented or Reserved
Figure 13-3. IIC Address Register (IIC1A)
Table 13-1. IIC1A Field Descriptions
Field
Description
7–1
AD[7:1]
Slave Address. The AD[7:1] field contains the slave address to be used by the IIC module. This field is used on
the 7-bit address scheme and the lower seven bits of the 10-bit address scheme.
13.3.2
IIC Frequency Divider Register (IIC1F)
7
6
5
4
3
2
1
0
0
0
0
R
MULT
ICR
W
Reset
0
0
0
0
0
Figure 13-4. IIC Frequency Divider Register (IIC1F)
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
Table 13-2. IIC1F Field Descriptions
Field
7–6
MULT
5–0
ICR
Description
IIC Multiplier Factor. The MULT bits define the multiplier factor, mul. This factor, along with the SCL divider,
generates the IIC baud rate. The multiplier factor mul as defined by the MULT bits is provided below.
00 mul = 01
01 mul = 02
10 mul = 04
11 Reserved
IIC Clock Rate. The ICR bits are used to prescale the bus clock for bit rate selection. These bits and the MULT
bits determine the IIC baud rate, the SDA hold time, the SCL Start hold time, and the SCL Stop hold time.
Table 13-4 provides the SCL divider and hold values for corresponding values of the ICR.
The SCL divider multiplied by multiplier factor mul generates IIC baud rate.
bus speed (Hz)
IIC baud rate = --------------------------------------------mul × SCLdivider
Eqn. 13-1
SDA hold time is the delay from the falling edge of SCL (IIC clock) to the changing of SDA (IIC data).
SDA hold time = bus period (s) × mul × SDA hold value
Eqn. 13-2
SCL start hold time is the delay from the falling edge of SDA (IIC data) while SCL is high (Start condition) to the
falling edge of SCL (IIC clock).
SCL Start hold time = bus period (s) × mul × SCL Start hold value
Eqn. 13-3
SCL stop hold time is the delay from the rising edge of SCL (IIC clock) to the rising edge of SDA
SDA (IIC data) while SCL is high (Stop condition).
SCL Stop hold time = bus period (s) × mul × SCL Stop hold value
Eqn. 13-4
For example, if the bus speed is 8 MHz, the table below shows the possible hold time values with different
ICR and MULT selections to achieve an IIC baud rate of 100kbps.
Table 13-3. Hold Time Values for 8 MHz Bus Speed
Hold Times (μs)
MULT
ICR
SDA
SCL Start
SCL Stop
0x2
0x00
3.500
3.000
5.500
0x1
0x07
2.500
4.000
5.250
0x1
0x0B
2.250
4.000
5.250
0x0
0x14
2.125
4.250
5.125
0x0
0x18
1.125
4.750
5.125
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (S08IICV2)
Table 13-4. IIC Divider and Hold Values
ICR
(hex)
SCL
Divider
SDA Hold
Value
SCL Hold
(Start)
Value
SDA Hold
(Stop)
Value
ICR
(hex)
SCL
Divider
SDA Hold
Value
SCL Hold
(Start)
Value
SCL Hold
(Stop)
Value
00
20
7
6
11
20
160
17
78
81
01
22
7
7
12
21
192
17
94
97
02
24
8
8
13
22
224
33
110
113
03
26
8
9
14
23
256
33
126
129
04
28
9
10
15
24
288
49
142
145
05
30
9
11
16
25
320
49
158
161
06
34
10
13
18
26
384
65
190
193
07
40
10
16
21
27
480
65
238
241
08
28
7
10
15
28
320
33
158
161
09
32
7
12
17
29
384
33
190
193
0A
36
9
14
19
2A
448
65
222
225
0B
40
9
16
21
2B
512
65
254
257
0C
44
11
18
23
2C
576
97
286
289
0D
48
11
20
25
2D
640
97
318
321
0E
56
13
24
29
2E
768
129
382
385
0F
68
13
30
35
2F
960
129
478
481
10
48
9
18
25
30
640
65
318
321
11
56
9
22
29
31
768
65
382
385
12
64
13
26
33
32
896
129
446
449
13
72
13
30
37
33
1024
129
510
513
14
80
17
34
41
34
1152
193
574
577
15
88
17
38
45
35
1280
193
638
641
16
104
21
46
53
36
1536
257
766
769
17
128
21
58
65
37
1920
257
958
961
18
80
9
38
41
38
1280
129
638
641
19
96
9
46
49
39
1536
129
766
769
1A
112
17
54
57
3A
1792
257
894
897
1B
128
17
62
65
3B
2048
257
1022
1025
1C
144
25
70
73
3C
2304
385
1150
1153
1D
160
25
78
81
3D
2560
385
1278
1281
1E
192
33
94
97
3E
3072
513
1534
1537
1F
240
33
118
121
3F
3840
513
1918
1921
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
235
Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.3.3
IIC Control Register (IIC1C1)
7
6
5
4
3
IICEN
IICIE
MST
TX
TXAK
R
W
Reset
2
1
0
0
0
0
0
0
RSTA
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 13-5. IIC Control Register (IIC1C1)
Table 13-5. IIC1C1 Field Descriptions
Field
Description
7
IICEN
IIC Enable. The IICEN bit determines whether the IIC module is enabled.
0 IIC is not enabled
1 IIC is enabled
6
IICIE
IIC Interrupt Enable. The IICIE bit determines whether an IIC interrupt is requested.
0 IIC interrupt request not enabled
1 IIC interrupt request enabled
5
MST
Master Mode Select. The MST bit changes from a 0 to a 1 when a start signal is generated on the bus and
master mode is selected. When this bit changes from a 1 to a 0 a stop signal is generated and the mode of
operation changes from master to slave.
0 Slave mode
1 Master mode
4
TX
Transmit Mode Select. The TX bit selects the direction of master and slave transfers. In master mode, this bit
should be set according to the type of transfer required. Therefore, for address cycles, this bit is always high.
When addressed as a slave, this bit should be set by software according to the SRW bit in the status register.
0 Receive
1 Transmit
3
TXAK
Transmit Acknowledge Enable. This bit specifies the value driven onto the SDA during data acknowledge
cycles for master and slave receivers.
0 An acknowledge signal is sent out to the bus after receiving one data byte
1 No acknowledge signal response is sent
2
RSTA
Repeat start. Writing a 1 to this bit generates a repeated start condition provided it is the current master. This
bit is always read as cleared. Attempting a repeat at the wrong time results in loss of arbitration.
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.3.4
IIC Status Register (IIC1S)
7
R
6
TCF
5
4
BUSY
IAAS
3
2
0
SRW
ARBL
1
0
RXAK
IICIF
W
Reset
1
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 13-6. IIC Status Register (IIC1S)
Table 13-6. IIC1S Field Descriptions
Field
Description
7
TCF
Transfer Complete Flag. This bit is set on the completion of a byte transfer. This bit is only valid during or
immediately following a transfer to the IIC module or from the IIC module.The TCF bit is cleared by reading the
IIC1D register in receive mode or writing to the IIC1D in transmit mode.
0 Transfer in progress
1 Transfer complete
6
IAAS
Addressed as a Slave. The IAAS bit is set when the calling address matches the programmed slave address
or when the GCAEN bit is set and a general call is received. Writing the IIC1C register clears this bit.
0 Not addressed
1 Addressed as a slave
5
BUSY
Bus Busy. The BUSY bit indicates the status of the bus regardless of slave or master mode. The BUSY bit is
set when a start signal is detected and cleared when a stop signal is detected.
0 Bus is idle
1 Bus is busy
4
ARBL
Arbitration Lost. This bit is set by hardware when the arbitration procedure is lost. The ARBL bit must be cleared
by software by writing a 1 to it.
0 Standard bus operation
1 Loss of arbitration
2
SRW
Slave Read/Write. When addressed as a slave, the SRW bit indicates the value of the R/W command bit of the
calling address sent to the master.
0 Slave receive, master writing to slave
1 Slave transmit, master reading from slave
1
IICIF
IIC Interrupt Flag. The IICIF bit is set when an interrupt is pending. This bit must be cleared by software, by
writing a 1 to it in the interrupt routine. One of the following events can set the IICIF bit:
• One byte transfer completes
• Match of slave address to calling address
• Arbitration lost
0 No interrupt pending
1 Interrupt pending
0
RXAK
Receive Acknowledge. When the RXAK bit is low, it indicates an acknowledge signal has been received after
the completion of one byte of data transmission on the bus. If the RXAK bit is high it means that no acknowledge
signal is detected.
0 Acknowledge received
1 No acknowledge received
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
237
Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.3.5
IIC Data I/O Register (IIC1D)
7
6
5
4
3
2
1
0
0
0
0
0
R
DATA
W
Reset
0
0
0
0
Figure 13-7. IIC Data I/O Register (IIC1D)
Table 13-7. IIC1D Field Descriptions
Field
Description
7–0
DATA
Data — In master transmit mode, when data is written to the IIC1D, a data transfer is initiated. The most
significant bit is sent first. In master receive mode, reading this register initiates receiving of the next byte of data.
NOTE
When transitioning out of master receive mode, the IIC mode should be
switched before reading the IIC1D register to prevent an inadvertent
initiation of a master receive data transfer.
In slave mode, the same functions are available after an address match has occurred.
The TX bit in IIC1C 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, reading the IIC1D does not initiate the receive.
Reading the IIC1D returns the last byte received while the IIC is configured in master receive or slave
receive modes. The IIC1D does not reflect every byte transmitted on the IIC bus, nor can software verify
that a byte has been written to the IIC1D correctly by reading it back.
In master transmit mode, the first byte of data written to IIC1D following assertion of MST is used for the
address transfer and should comprise of the calling address (in bit 7 to bit 1) concatenated with the required
R/W bit (in position bit 0).
13.3.6
IIC Control Register 2 (IIC1C2)
7
6
GCAEN
ADEXT
0
0
R
5
4
3
0
0
0
2
1
0
AD10
AD9
AD8
0
0
0
W
Reset
0
0
0
= Unimplemented or Reserved
Figure 13-8. IIC Control Register (IIC1C2)
MC9S08AC16 Series Data Sheet, Rev. 0
238
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Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (S08IICV2)
Table 13-8. IIC1C2 Field Descriptions
Field
Description
7
GCAEN
General Call Address Enable. The GCAEN bit enables or disables general call address.
0 General call address is disabled
1 General call address is enabled
6
ADEXT
Address Extension. The ADEXT bit controls the number of bits used for the slave address.
0 7-bit address scheme
1 10-bit address scheme
2–0
AD[10:8]
Slave Address. The AD[10:8] field contains the upper three bits of the slave address in the 10-bit address
scheme. This field is only valid when the ADEXT bit is set.
13.4
Functional Description
This section provides a complete functional description of the IIC module.
13.4.1
IIC 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. A 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
• Stop signal
The stop signal should not be confused with the CPU stop instruction. The IIC bus system communication
is described briefly in the following sections and illustrated in Figure 13-9.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
msb
SCL
1
SDA
lsb
2
3
4
5
6
7
8
msb
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Start
Signal
1
SDA
3
4
5
6
7
8
Calling Address
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
1
XX
Read/ Ack
Write Bit
9
No
Ack
Bit
msb
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
Start
Signal
2
Data Byte
lsb
2
1
Read/ Ack
Write Bit
Calling Address
msb
SCL
XXX
lsb
Stop
Signal
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
Ack
Bit
Stop
Signal
Figure 13-9. IIC Bus Transmission Signals
13.4.1.1
Start Signal
When the bus is free, no master device is engaging the bus (SCL and SDA lines are at logical high), a
master may initiate communication by sending a start signal. As shown in Figure 13-9, 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.
13.4.1.2
Slave Address Transmission
The first byte of data transferred 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 responds by sending
back an acknowledge bit. This is done by pulling the SDA low at the ninth clock (see Figure 13-9).
No two slaves in the system may have the same address. If the IIC module is the master, it must not transmit
an address equal to its own slave address. The IIC cannot be master and slave at the same time. However,
if arbitration is lost during an address cycle, the IIC reverts to slave mode and operates correctly even if it
is being addressed by another master.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.4.1.3
Data Transfer
Before 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 13-9. There is one clock pulse on SCL for each data bit, the msb being
transferred first. Each data byte is followed by a 9th (acknowledge) bit, which is signalled from the
receiving device. An acknowledge is signalled by pulling the SDA low at the ninth clock. In summary, one
complete data transfer needs nine clock pulses.
If the slave receiver does not acknowledge the master in the ninth bit time, the SDA line must be left high
by the slave. The master interprets the failed acknowledge as an unsuccessful data transfer.
If the master receiver does not acknowledge the slave transmitter after a data byte transmission, the slave
interprets this as an end of data transfer and releases the SDA line.
In either case, the data transfer is aborted and the master does one of two things:
• Relinquishes the bus by generating a stop signal.
• Commences a new calling by generating a repeated start signal.
13.4.1.4
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 13-9).
The master can generate a stop even if the slave has generated an acknowledge at which point the slave
must release the bus.
13.4.1.5
Repeated Start Signal
As shown in Figure 13-9, 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.
13.4.1.6
Arbitration Procedure
The IIC 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,
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
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.
13.4.1.7
Clock Synchronization
Because wire-AND logic is performed on the SCL line, a high-to-low transition on the SCL line affects all
the devices connected on the bus. The devices start counting their low period and after 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 still 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 13-10). 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.
Delay
Start Counting High Period
SCL1
SCL2
SCL
Internal Counter Reset
Figure 13-10. IIC Clock Synchronization
13.4.1.8
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 a case, it halts the bus clock and forces
the master clock into wait states until the slave releases the SCL line.
13.4.1.9
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.
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.4.2
10-bit Address
For 10-bit addressing, 0x11110 is used for the first 5 bits of the first address byte. Various combinations of
read/write formats are possible within a transfer that includes 10-bit addressing.
13.4.2.1
Master-Transmitter Addresses a Slave-Receiver
The transfer direction is not changed (see Table 13-9). When a 10-bit address follows a start condition,
each slave compares the first seven bits of the first byte of the slave address (11110XX) with its own
address and tests whether the eighth bit (R/W direction bit) is 0. More than one device can find a match
and generate an acknowledge (A1). Then, each slave that finds a match compares the eight bits of the
second byte of the slave address with its own address. Only one slave finds a match and generates an
acknowledge (A2). The matching slave remains addressed by the master until it receives a stop condition
(P) or a repeated start condition (Sr) followed by a different slave address.
S
Slave Address 1st 7 bits
R/W
11110 + AD10 + AD9
0
A1
Slave Address 2nd byte
AD[8:1]
A2
Data
A
...
Data
A/A
P
Table 13-9. Master-Transmitter Addresses Slave-Receiver with a 10-bit Address
After the master-transmitter has sent the first byte of the 10-bit address, the slave-receiver sees an IIC
interrupt. Software must ensure the contents of IICD are ignored and not treated as valid data for this
interrupt.
13.4.2.2
Master-Receiver Addresses a Slave-Transmitter
The transfer direction is changed after the second R/W bit (see Table 13-10). Up to and including
acknowledge bit A2, the procedure is the same as that described for a master-transmitter addressing a
slave-receiver. After the repeated start condition (Sr), a matching slave remembers that it was addressed
before. This slave then checks whether the first seven bits of the first byte of the slave address following
Sr are the same as they were after the start condition (S) and tests whether the eighth (R/W) bit is 1. If there
is a match, the slave considers that it has been addressed as a transmitter and generates acknowledge A3.
The slave-transmitter remains addressed until it receives a stop condition (P) or a repeated start condition
(Sr) followed by a different slave address.
After a repeated start condition (Sr), all other slave devices also compare the first seven bits of the first byte
of the slave address with their own addresses and test the eighth (R/W) bit. However, none of them are
addressed because R/W = 1 (for 10-bit devices) or the 11110XX slave address (for 7-bit devices) does not
match.
S
Slave Address
1st 7 bits
R/W
11110 + AD10 + AD9
0
A1
Slave Address
2nd byte
AD[8:1]
A2
Sr
Slave Address
1st 7 bits
R/W
11110 + AD10 + AD9
1
A3
Data
A
...
Data
A
P
Table 13-10. Master-Receiver Addresses a Slave-Transmitter with a 10-bit Address
After the master-receiver has sent the first byte of the 10-bit address, the slave-transmitter sees an IIC
interrupt. Software must ensure the contents of IICD are ignored and not treated as valid data for this
interrupt.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.4.3
General Call Address
General calls can be requested in 7-bit address or 10-bit address. If the GCAEN bit is set, the IIC matches
the general call address as well as its own slave address. When the IIC responds to a general call, it acts as
a slave-receiver and the IAAS bit is set after the address cycle. Software must read the IICD register after
the first byte transfer to determine whether the address matches is its own slave address or a general call.
If the value is 00, the match is a general call. If the GCAEN bit is clear, the IIC ignores any data supplied
from a general call address by not issuing an acknowledgement.
13.5
Resets
The IIC is disabled after reset. The IIC cannot cause an MCU reset.
13.6
Interrupts
The IIC generates a single interrupt.
An interrupt from the IIC is generated when any of the events in Table 13-11 occur, provided the IICIE bit
is set. The interrupt is driven by bit IICIF (of the IIC status register) and masked with bit IICIE (of the IIC
control register). The IICIF bit must be cleared by software by writing a 1 to it in the interrupt routine. You
can determine the interrupt type by reading the status register.
Table 13-11. Interrupt Summary
13.6.1
Interrupt Source
Status
Flag
Local Enable
Complete 1-byte transfer
TCF
IICIF
IICIE
Match of received calling address
IAAS
IICIF
IICIE
Arbitration Lost
ARBL
IICIF
IICIE
Byte Transfer Interrupt
The TCF (transfer complete flag) bit is set at the falling edge of the ninth clock to indicate the completion
of byte transfer.
13.6.2
Address Detect Interrupt
When the calling address matches the programmed slave address (IIC address register) or when the
GCAEN bit is set and a general call is received, the IAAS bit in the status register is set. The CPU is
interrupted, provided the IICIE is set. The CPU must check the SRW bit and set its Tx mode accordingly.
13.6.3
Arbitration Lost Interrupt
The IIC 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, the relative priority of the contending masters is determined
by a data arbitration procedure. The IIC module asserts this interrupt when it loses the data arbitration
process and the ARBL bit in the status register is set.
MC9S08AC16 Series Data Sheet, Rev. 0
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
Arbitration is lost in the following circumstances:
• SDA sampled as a low when the master drives a high during an address or data transmit cycle.
• SDA sampled as a low when the master drives a high during the acknowledge bit of a data receive
cycle.
• A start cycle is attempted when the bus is busy.
• A repeated start cycle is requested in slave mode.
• A stop condition is detected when the master did not request it.
This bit must be cleared by software writing a 1 to it.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
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Chapter 13 Inter-Integrated Circuit (S08IICV2)
13.7
1.
2.
3.
4.
5.
1.
2.
3.
4.
5.
6.
7.
Initialization/Application Information
Module Initialization (Slave)
Write: IICC2
— to enable or disable general call
— to select 10-bit or 7-bit addressing mode
Write: IICA
— to set the slave address
Write: IICC1
— to enable IIC and interrupts
Initialize RAM variables (IICEN = 1 and IICIE = 1) for transmit data
Initialize RAM variables used to achieve the routine shown in Figure 13-12
Module Initialization (Master)
Write: IICF
— to set the IIC baud rate (example provided in this chapter)
Write: IICC1
— to enable IIC and interrupts
Initialize RAM variables (IICEN = 1 and IICIE = 1) for transmit data
Initialize RAM variables used to achieve the routine shown in Figure 13-12
Write: IICC1
— to enable TX
Write: IICC1
— to enable MST (master mode)
Write: IICD
— with the address of the target slave. (The lsb of this byte determines whether the communication is
master receive or transmit.)
Module Use
The routine shown in Figure 13-12 can handle both master and slave IIC operations. For slave operation, an
incoming IIC message that contains the proper address begins IIC communication. For master operation,
communication must be initiated by writing to the IICD register.
Register Model
0
AD[7:1]
IICA
When addressed as a slave (in slave mode), the module responds to this address
MULT
IICF
ICR
Baud rate = BUSCLK / (2 x MULT x (SCL DIVIDER))
IICC1
IICEN
IICIE
MST
TX
TXAK
RSTA
0
0
BUSY
ARBL
0
SRW
IICIF
RXAK
AD9
AD8
Module configuration
IICS
TCF
IAAS
Module status flags
DATA
IICD
Data register; Write to transmit IIC data read to read IIC data
IICC2 GCAEN ADEXT
0
0
0
AD10
Address configuration
Figure 13-11. IIC Module Quick Start
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (S08IICV2)
Clear
IICIF
Master
Mode
?
Y
TX
N
Y
RX
Tx/Rx
?
Arbitration
Lost
?
N
Last Byte
Transmitted
?
N
Clear ARBL
Y
RXAK=0
?
Last
Byte to Be Read
?
N
N
N
Y
Y
IAAS=1
?
Y
IAAS=1
?
Y
Address Transfer
See Note 1
Y
End of
Addr Cycle
(Master Rx)
?
Y
Y
(Read)
2nd Last
Byte to Be Read
?
N
SRW=1
?
Write Next
Byte to IICD
Set TXACK =1
Generate
Stop Signal
(MST = 0)
Switch to
Rx Mode
Generate
Stop Signal
(MST = 0)
Read Data
from IICD
and Store
ACK from
Receiver
?
N
Read Data
from IICD
and Store
Tx Next
Byte
Write Data
to IICD
Dummy Read
from IICD
TX
Y
Set TX
Mode
RX
TX/RX
?
N (Write)
N
N
Data Transfer
See Note 2
Set RX
Mode
Switch to
Rx Mode
Dummy Read
from IICD
Dummy Read
from IICD
RTI
NOTES:
1. If general call is enabled, a check must be done to determine whether the received address was a general call address (0x00). If the received address was a
general call address, then the general call must be handled by user software.
2. When 10-bit addressing is used to address a slave, the slave sees an interrupt following the first byte of the extended address. User software must ensure that for
this interrupt, the contents of IICD are ignored and not treated as a valid data transfer
Figure 13-12. Typical IIC Interrupt Routine
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
247
Chapter 13 Inter-Integrated Circuit (S08IICV2)
MC9S08AC16 Series Data Sheet, Rev. 0
248
PRELIMINARY
Freescale Semiconductor
Chapter 14
Analog-to-Digital Converter (S08ADC10V1)
14.1
Overview
The 10-bit analog-to-digital converter (ADC) is a successive approximation ADC designed for operation
within an integrated microcontroller system-on-chip. The ADC module design supports up to 28 separate
analog inputs (AD0-AD27). Only 9 (AD0-AD3, AD8-AD11, and AD27) of the possible inputs are
implemented on the MC9S08AC16 Series Family of MCUs. These inputs are selected by the ADCH bits.
Some inputs are shared with I/O pins as shown in Figure 14-1. All of the channel assignments of the ADC
for the MC9S08AC16 Series devices are summarized in Table 14-1.
14.2
Channel Assignments
The ADC channel assignments for the MC9S08AC16 Series devices are shown in the table below.
Channels that are unimplemented are internally connected to VREFL. Reserved channels convert to an
unknown value. Channels which are connected to an I/O pin have an associated pin control bit as shown.
Table 14-1. ADC Channel Assignment
ADCH
Channel
Input
Pin Control
ADCH
Channel
Input
Pin Control
00000
AD0
PTB0/AD1P0
ADPC0
10000
AD16
VREFL
N/A
00001
AD1
PTB1/AD1P1
ADPC1
10001
AD17
VREFL
N/A
00010
AD2
PTB2/AD1P2
ADPC2
10010
AD18
VREFL
N/A
00011
AD3
PTB3/AD1P3
ADPC3
10011
AD19
VREFL
N/A
00100
AD4
VREFL
N/A
10100
AD20
VREFL
N/A
00101
AD5
VREFL
N/A
10101
AD21
VREFL
N/A
00110
AD6
VREFL
N/A
10110
AD22
Reserved
N/A
00111
AD7
VREFL
N/A
10111
AD23
Reserved
N/A
01000
AD8
PTD0/AD1P8
ADPC8
11000
AD24
Reserved
N/A
01001
AD9
PTD1/AD1P9
ADPC9
11001
AD25
Reserved
N/A
01010
AD10
PTD2/AD1P10
ADPC10
11010
AD26
Temp Sensor
N/A
01011
AD11
PTD3/AD1P11
ADPC11
11011
AD27
Internal Bandgap
N/A
01100
AD12
VREFL
N/A
11100
01101
AD13
VREFL
N/A
11101
Reserved
N/A
VREFH
VREFH
N/A
01110
AD14
VREFL
N/A
01111
AD15
VREFL
N/A
11110
VREFL
VREFL
N/A
11111
module
disabled
None
N/A
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
249
Chapter 14 Analog-to-Digital Converter (S08ADC10V1)
NOTE
Selecting the internal bandgap channel requires BGBE =1 in SPMSC1 see
Section 5.9.8, “System Power Management Status and Control 1 Register
(SPMSC1).” For value of bandgap voltage reference see Section A.6, “DC
Characteristics.”
14.2.1
Alternate Clock
The ADC module is capable of performing conversions using the MCU bus clock, the bus clock divided
by two, the local asynchronous clock (ADACK) within the module, or the alternate clock, ALTCLK. The
alternate clock for the MC9S08AC16 Series MCU devices is the external reference clock (ICGERCLK)
from the internal clock generator (ICG) module.
Because ICGERCLK is active only while an external clock source is enabled, the ICG must be configured
for either FBE or FEE mode (CLKS1 = 1). ICGERCLK must run at a frequency such that the ADC
conversion clock (ADCK) runs at a frequency within its specified range (fADCK) after being divided down
from the ALTCLK input as determined by the ADIV bits. For example, if the ADIV bits are set up to divide
by four, then the minimum frequency for ALTCLK (ICGERCLK) is four times the minimum value for
fADCK and the maximum frequency is four times the maximum value for fADCK. Because of the minimum
frequency requirement, when an oscillator circuit is used it must be configured for high range operation
(RANGE = 1).
ALTCLK is active while the MCU is in wait mode provided the conditions described above are met. This
allows ALTCLK to be used as the conversion clock source for the ADC while the MCU is in wait mode.
ALTCLK cannot be used as the ADC conversion clock source while the MCU is in stop3.
14.2.2
Hardware Trigger
The ADC hardware trigger, ADHWT, is output from the real time interrupt (RTI) counter. The RTI counter
can be clocked by either ICGERCLK or a nominal 1 kHz clock source within the RTI block. The 1-kHz
clock source can be used with the MCU in run, wait, or stop3. With the ICG configured for either FBE or
FEE mode, ICGERCLK can be used with the MCU in run or wait.
The period of the RTI is determined by the input clock frequency and the RTIS bits. When the ADC
hardware trigger is enabled, a conversion is initiated upon an RTI counter overflow. The RTI counter is a
free running counter that generates an overflow at the RTI rate determined by the RTIS bits.
14.2.2.1
Analog Pin Enables
The ADC on MC9S08AC16 Series contains only two analog pin enable registers, APCTL1 and APCTL2.
14.2.2.2
Low-Power Mode Operation
The ADC is capable of running in stop3 mode but requires LVDSE and LVDE in SPMSC1 to be set.
MC9S08AC16 Series Data Sheet, Rev. 0
250
PRELIMINARY
Freescale Semiconductor
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ADC1)
HCS08 CORE
IRQ/TPMCLK
CPU
PTA7
PTA2
PTA1
PTA0
PTB3/AD1P3
PTB2/AD1P2
PTB1/TPM3CH1 /AD1P1
PTB0/TPM3CH0 /AD1P0
SDA1
IIC MODULE (IIC1)
SCL1
INTERNAL CLOCK
GENERATOR (ICG)
EXTAL
XTAL
PORT C
RESET
4 AD1P11–AD1P8
DEBUG
MODULE (DBG)
BKGD/MS
BDC
4 AD1P3–AD1P0
PORT A
VDDAD
VSSAD
VREFL
VREFH
PORT B
Chapter 14 Analog-to-Digital Converter (S08ADC10V1)
HCS08 SYSTEM CONTROL
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PTC5/RxD2
PTC4
PTC3/TxD2
PTC2/MCLK
PTC1/SDA1
PTC0/SCL1
TPMCLK
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
USER FLASH
16,384 BYTES
OR 8192 BYTES
VDD
VSS
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
5 KBIP4–KBIP0
PORT D
LVD
2 KBIP6–KBIP5
PTD3/KBIP6/AD1P11
PTD2/KBIP5/AD1P10
PTD1/AD1P9
PTD0/AD1P8
PORT E
7-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PTE7/SPSCK1
PTE6/MOSI1
PTE5/MISO1
PTE4/SS1
PTE3/TPM1CH1
PTE2/TPM1CH0
PTE1/RxD1
PTE0/TxD1
PORT F
IRQ
COP
PTF6
PTF5/TPM2CH1
PTF4/TPM2CH0
PTF1/TPM1CH3
PTF0/TPM1CH2
PORT G
LOW-POWER OSCILLATOR
RTI
PTG6/EXTAL
PTG5/XTAL
PTG4/KBIP4
PTG3/KBIP3
PTG2/KBIP2
PTG1/KBIP1
PTG0/KBIP0
RxD1
TxD1
RxD2
TxD2
SPSCK1
MOSI1
MISO1
SS1
4-CHANNEL TIMER/PWM
MODULE (TPM1)
TPM1CH1
TPM1CH0
TPM1CH3
TPM1CH2
USER RAM
1024 BYTES
OR 768 BYTES
2-CHANNEL TIMER/PWM
MODULE (TPM2)
TPM2CH1
TPM2CH0
VOLTAGE
REGULATOR
2-CHANNEL TIMER/PWM
MODULE (TPM3)
TPM3CH1
TPM3CH0
= Not available on 32-, or 44-pin packages
= Not available on 32-pin packages
= Not available on 32-pin packages
= Not available on S9S08AWxxA devices
Notes:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ is enabled (IRQPE = 1). Pulldown is enabled
if rising edge detect is selected (IRQEDG = 1)
3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD.
4. Pin contains integrated pullup device.
5. PTD3, PTD2, and PTG4 contain both pullup and pulldown devices. Pulldown enabled when KBI is enabled
(KBIPEn = 1) and rising edge is selected (KBEDGn = 1).
Figure 14-1. MC9S08AC16 Block Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
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14.2.3
Temperature Sensor
The ADC1 module includes a temperature sensor whose output is connected to one of the ADC analog
channel inputs. Equation 14-1 provides an approximate transfer function of the temperature sensor.
Temp = 25 - ((VTEMP -VTEMP25) ÷ m)
Eqn. 14-1
where:
— VTEMP is the voltage of the temperature sensor channel at the ambient temperature.
— VTEMP25 is the voltage of the temperature sensor channel at 25°C.
— m is the hot or cold voltage versus temperature slope in V/°C.
For temperature calculations, use the VTEMP25 and m values from the ADC Electricals table.
In application code, the user reads the temperature sensor channel, calculates VTEMP, and compares to
VTEMP25 . If VTEMP is greater than VTEMP25 the cold slope value is applied in Equation 14-1. If VTEMP is
less than VTEMP25 the hot slope value is applied in Equation 14-1.
For more information on using the temperature sensor, consult AN3031.
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14.2.4
Features
Features of the ADC module include:
• Linear successive approximation algorithm with 10 bits resolution.
• Up to 28 analog inputs.
• Output formatted in 10- or 8-bit right-justified format.
• Single or continuous conversion (automatic return to idle after single conversion).
• Configurable sample time and conversion speed/power.
• Conversion complete flag and interrupt.
• Input clock selectable from up to four sources.
• Operation in wait or stop3 modes for lower noise operation.
• Asynchronous clock source for lower noise operation.
• Selectable asynchronous hardware conversion trigger.
• Automatic compare with interrupt for less-than, or greater-than or equal-to, programmable value.
• Temperature sensor.
14.2.5
Block Diagram
Figure 14-2 provides a block diagram of the ADC module
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ADIV
ADLPC
MODE
ADLSMP
ADTRG
2
ADCO
ADCH
1
ADC1CFG
complete
COCO
ADC1SC1
ADICLK
Compare true
AIEN
3
Async
Clock Gen
ADACK
MCU STOP
ADCK
÷2
ALTCLK
abort
transfer
sample
initialize
•••
AD0
convert
Control Sequencer
ADHWT
Bus Clock
Clock
Divide
AIEN 1
Interrupt
COCO 2
ADVIN
SAR Converter
AD27
VREFH
Data Registers
Sum
VREFL
Compare true
3
ACFGT
Value
Compare
Logic
ADC1SC2
Compare Value Registers
Figure 14-2. ADC Block Diagram
14.3
External Signal Description
The ADC module supports up to 28 separate analog inputs. It also requires four supply/reference/ground
connections.
Table 14-2. Signal Properties
Name
Function
AD27–AD0
Analog Channel inputs
VREFH
High reference voltage
VREFL
Low reference voltage
VDDAD
Analog power supply
VSSAD
Analog ground
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14.3.1
Analog Power (VDDAD)
The ADC analog portion uses VDDAD as its power connection. In some packages, VDDAD is connected
internally to VDD. If externally available, connect the VDDAD pin to the same voltage potential as VDD.
External filtering may be necessary to ensure clean VDDAD for good results.
14.3.2
Analog Ground (VSSAD)
The ADC analog portion uses VSSAD as its ground connection. In some packages, VSSAD is connected
internally to VSS. If externally available, connect the VSSAD pin to the same voltage potential as VSS.
14.3.3
Voltage Reference High (VREFH)
VREFH is the high reference voltage for the converter. In some packages, VREFH is connected internally to
VDDAD. If externally available, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD).
14.3.4
Voltage Reference Low (VREFL)
VREFL is the low reference voltage for the converter. In some packages, VREFL is connected internally to
VSSAD. If externally available, connect the VREFL pin to the same voltage potential as VSSAD.
14.3.5
Analog Channel Inputs (ADx)
The ADC module supports up to 28 separate analog inputs. An input is selected for conversion through the
ADCH channel select bits.
14.4
Register Definition
These memory mapped registers control and monitor operation of the ADC:
•
•
•
•
•
•
Status and control register, ADC1SC1
Status and control register, ADC1SC2
Data result registers, ADC1RH and ADC1RL
Compare value registers, ADC1CVH and ADC1CVL
Configuration register, ADC1CFG
Pin enable registers, APCTL1, APCTL2, APCTL3
14.4.1
Status and Control Register 1 (ADC1SC1)
This section describes the function of the ADC status and control register (ADC1SC1). Writing ADC1SC1
aborts the current conversion and initiates a new conversion (if the ADCH bits are equal to a value other
than all 1s).
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7
R
6
5
4
AIEN
ADCO
0
0
3
2
1
0
1
1
COCO
ADCH
W
Reset:
0
1
1
1
= Unimplemented or Reserved
Figure 14-3. Status and Control Register (ADC1SC1)
Table 14-3. ADC1SC1 Register Field Descriptions
Field
Description
7
COCO
Conversion Complete Flag — The COCO flag is a read-only bit which is set each time a conversion is
completed when the compare function is disabled (ACFE = 0). When the compare function is enabled (ACFE =
1) the COCO flag is set upon completion of a conversion only if the compare result is true. This bit is cleared
whenever ADC1SC1 is written or whenever ADC1RL is read.
0 Conversion not completed
1 Conversion completed
6
AIEN
Interrupt Enable — AIEN is used to enable conversion complete interrupts. When COCO becomes set while
AIEN is high, an interrupt is asserted.
0 Conversion complete interrupt disabled
1 Conversion complete interrupt enabled
5
ADCO
Continuous Conversion Enable — ADCO is used to enable continuous conversions.
0 One conversion following a write to the ADC1SC1 when software triggered operation is selected, or one
conversion following assertion of ADHWT when hardware triggered operation is selected.
1 Continuous conversions initiated following a write to ADC1SC1 when software triggered operation is selected.
Continuous conversions are initiated by an ADHWT event when hardware triggered operation is selected.
4:0
ADCH
Input Channel Select — The ADCH bits form a 5-bit field which is used to select one of the input channels. The
input channels are detailed in Figure 14-4.
The successive approximation converter subsystem is turned off when the channel select bits are all set to 1.
This feature allows for explicit disabling of the ADC and isolation of the input channel from all sources.
Terminating continuous conversions this way will prevent an additional, single conversion from being performed.
It is not necessary to set the channel select bits to all 1s to place the ADC in a low-power state when continuous
conversions are not enabled because the module automatically enters a low-power state when a conversion
completes.
Figure 14-4. Input Channel Select
ADCH
Input Select
ADCH
Input Select
00000
AD0
10000
AD16
00001
AD1
10001
AD17
00010
AD2
10010
AD18
00011
AD3
10011
AD19
00100
AD4
10100
AD20
00101
AD5
10101
AD21
00110
AD6
10110
AD22
00111
AD7
10111
AD23
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Figure 14-4. Input Channel Select (continued)
14.4.2
ADCH
Input Select
ADCH
Input Select
01000
AD8
11000
AD24
01001
AD9
11001
AD25
01010
AD10
11010
AD26
01011
AD11
11011
AD27
01100
AD12
11100
Reserved
01101
AD13
11101
VREFH
01110
AD14
11110
VREFL
01111
AD15
11111
Module disabled
Status and Control Register 2 (ADC1SC2)
The ADC1SC2 register is used to control the compare function, conversion trigger and conversion active
of the ADC module.
7
R
6
5
4
ADTRG
ACFE
ACFGT
0
0
0
ADACT
3
2
0
0
0
0
1
0
R1
R1
0
0
W
Reset:
0
= Unimplemented or Reserved
1
Bits 1 and 0 are reserved bits that must always be written to 0.
Figure 14-5. Status and Control Register 2 (ADC1SC2)
Table 14-4. ADC1SC2 Register Field Descriptions
Field
Description
7
ADACT
Conversion Active — ADACT indicates that a conversion is in progress. ADACT is set when a conversion is
initiated and cleared when a conversion is completed or aborted.
0 Conversion not in progress
1 Conversion in progress
6
ADTRG
Conversion Trigger Select — ADTRG is used to select the type of trigger to be used for initiating a conversion.
Two types of trigger are selectable: software trigger and hardware trigger. When software trigger is selected, a
conversion is initiated following a write to ADC1SC1. When hardware trigger is selected, a conversion is initiated
following the assertion of the ADHWT input.
0 Software trigger selected
1 Hardware trigger selected
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Table 14-4. ADC1SC2 Register Field Descriptions (continued)
Field
Description
5
ACFE
Compare Function Enable — ACFE is used to enable the compare function.
0 Compare function disabled
1 Compare function enabled
4
ACFGT
Compare Function Greater Than Enable — ACFGT is used to configure the compare function to trigger when
the result of the conversion of the input being monitored is greater than or equal to the compare value. The
compare function defaults to triggering when the result of the compare of the input being monitored is less than
the compare value.
0 Compare triggers when input is less than compare level
1 Compare triggers when input is greater than or equal to compare level
14.4.3
Data Result High Register (ADC1RH)
ADC1RH contains the upper two bits of the result of a 10-bit conversion. When configured for 8-bit
conversions both ADR8 and ADR9 are equal to zero. ADC1RH is updated each time a conversion
completes except when automatic compare is enabled and the compare condition is not met. In 10-bit
MODE, reading ADC1RH prevents the ADC from transferring subsequent conversion results into the
result registers until ADC1RL is read. If ADC1RL is not read until after the next conversion is completed,
then the intermediate conversion result will be lost. In 8-bit mode there is no interlocking with ADC1RL.
In the case that the MODE bits are changed, any data in ADC1RH becomes invalid.
R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
ADR9
ADR8
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented or Reserved
Figure 14-6. Data Result High Register (ADC1RH)
14.4.4
Data Result Low Register (ADC1RL)
ADC1RL contains the lower eight bits of the result of a 10-bit conversion, and all eight bits of an 8-bit
conversion. This register is updated each time a conversion completes except when automatic compare is
enabled and the compare condition is not met. In 10-bit mode, reading ADC1RH prevents the ADC from
transferring subsequent conversion results into the result registers until ADC1RL is read. If ADC1RL is
not read until the after next conversion is completed, then the intermediate conversion results will be lost.
In 8-bit mode, there is no interlocking with ADC1RH. In the case that the MODE bits are changed, any
data in ADC1RL becomes invalid.
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R
7
6
5
4
3
2
1
0
ADR7
ADR6
ADR5
ADR4
ADR3
ADR2
ADR1
ADR0
0
0
0
0
0
0
0
0
W
Reset:
= Unimplemented or Reserved
Figure 14-7. Data Result Low Register (ADC1RL)
14.4.5
Compare Value High Register (ADC1CVH)
This register holds the upper two bits of the 10-bit compare value. These bits are compared to the upper
two bits of the result following a conversion in 10-bit mode when the compare function is enabled.In 8-bit
operation, ADC1CVH is not used during compare.
R
7
6
5
4
0
0
0
0
3
2
1
0
ADCV9
ADCV8
0
0
W
Reset:
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 14-8. Compare Value High Register (ADC1CVH)
14.4.6
Compare Value Low Register (ADC1CVL)
This register holds the lower 8 bits of the 10-bit compare value, or all 8 bits of the 8-bit compare value.
Bits ADCV7:ADCV0 are compared to the lower 8 bits of the result following a conversion in either 10-bit
or 8-bit mode.
7
6
5
4
3
2
1
0
ADCV7
ADCV6
ADCV5
ADCV4
ADCV3
ADCV2
ADCV1
ADCV0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 14-9. Compare Value Low Register(ADC1CVL)
14.4.7
Configuration Register (ADC1CFG)
ADC1CFG is used to select the mode of operation, clock source, clock divide, and configure for low power
or long sample time.
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7
6
5
4
3
2
1
0
R
ADLPC
ADIV
ADLSMP
MODE
ADICLK
W
Reset:
0
0
0
0
0
0
0
0
Figure 14-10. Configuration Register (ADC1CFG)
Table 14-5. ADC1CFG Register Field Descriptions
Field
Description
7
ADLPC
Low Power Configuration — ADLPC controls the speed and power configuration of the successive
approximation converter. This is used to optimize power consumption when higher sample rates are not required.
0 High speed configuration
1 Low power configuration: {FC31}The power is reduced at the expense of maximum clock speed.
6:5
ADIV
Clock Divide Select — ADIV select the divide ratio used by the ADC to generate the internal clock ADCK.
Table 14-6 shows the available clock configurations.
4
ADLSMP
Long Sample Time Configuration — ADLSMP selects between long and short sample time. This adjusts the
sample period to allow higher impedance inputs to be accurately sampled or to maximize conversion speed for
lower impedance inputs. Longer sample times can also be used to lower overall power consumption when
continuous conversions are enabled if high conversion rates are not required.
0 Short sample time
1 Long sample time
3:2
MODE
Conversion Mode Selection — MODE bits are used to select between 10- or 8-bit operation. See Table 14-7.
1:0
ADICLK
Input Clock Select — ADICLK bits select the input clock source to generate the internal clock ADCK. See
Table 14-8.
Table 14-6. Clock Divide Select
ADIV
Divide Ratio
Clock Rate
00
1
Input clock
01
2
Input clock ÷ 2
10
4
Input clock ÷ 4
11
8
Input clock ÷ 8
Table 14-7. Conversion Modes
MODE
Mode Description
00
8-bit conversion (N=8)
01
Reserved
10
10-bit conversion (N=10)
11
Reserved
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Table 14-8. Input Clock Select
ADICLK
14.4.8
Selected Clock Source
00
Bus clock
01
Bus clock divided by 2
10
Alternate clock (ALTCLK)
11
Asynchronous clock (ADACK)
Pin Control 1 Register (APCTL1)
The pin control registers are used to disable the I/O port control of MCU pins used as analog inputs.
APCTL1 is used to control the pins associated with channels 0–7 of the ADC module.
7
6
5
4
3
2
1
0
ADPC7
ADPC6
ADPC5
ADPC4
ADPC3
ADPC2
ADPC1
ADPC0
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 14-11. Pin Control 1 Register (APCTL1)
Table 14-9. APCTL1 Register Field Descriptions
Field
Description
7
ADPC7
ADC Pin Control 7 — ADPC7 is used to control the pin associated with channel AD7.
0 AD7 pin I/O control enabled
1 AD7 pin I/O control disabled
6
ADPC6
ADC Pin Control 6 — ADPC6 is used to control the pin associated with channel AD6.
0 AD6 pin I/O control enabled
1 AD6 pin I/O control disabled
5
ADPC5
ADC Pin Control 5 — ADPC5 is used to control the pin associated with channel AD5.
0 AD5 pin I/O control enabled
1 AD5 pin I/O control disabled
4
ADPC4
ADC Pin Control 4 — ADPC4 is used to control the pin associated with channel AD4.
0 AD4 pin I/O control enabled
1 AD4 pin I/O control disabled
3
ADPC3
ADC Pin Control 3 — ADPC3 is used to control the pin associated with channel AD3.
0 AD3 pin I/O control enabled
1 AD3 pin I/O control disabled
2
ADPC2
ADC Pin Control 2 — ADPC2 is used to control the pin associated with channel AD2.
0 AD2 pin I/O control enabled
1 AD2 pin I/O control disabled
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Table 14-9. APCTL1 Register Field Descriptions (continued)
Field
Description
1
ADPC1
ADC Pin Control 1 — ADPC1 is used to control the pin associated with channel AD1.
0 AD1 pin I/O control enabled
1 AD1 pin I/O control disabled
0
ADPC0
ADC Pin Control 0 — ADPC0 is used to control the pin associated with channel AD0.
0 AD0 pin I/O control enabled
1 AD0 pin I/O control disabled
14.4.9
Pin Control 2 Register (APCTL2)
APCTL2 is used to control channels 8–15 of the ADC module.
7
6
5
4
3
2
1
0
ADPC15
ADPC14
ADPC13
ADPC12
ADPC11
ADPC10
ADPC9
ADPC8
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 14-12. Pin Control 2 Register (APCTL2)
Table 14-10. APCTL2 Register Field Descriptions
Field
Description
7
ADPC15
ADC Pin Control 15 — ADPC15 is used to control the pin associated with channel AD15.
0 AD15 pin I/O control enabled
1 AD15 pin I/O control disabled
6
ADPC14
ADC Pin Control 14 — ADPC14 is used to control the pin associated with channel AD14.
0 AD14 pin I/O control enabled
1 AD14 pin I/O control disabled
5
ADPC13
ADC Pin Control 13 — ADPC13 is used to control the pin associated with channel AD13.
0 AD13 pin I/O control enabled
1 AD13 pin I/O control disabled
4
ADPC12
ADC Pin Control 12 — ADPC12 is used to control the pin associated with channel AD12.
0 AD12 pin I/O control enabled
1 AD12 pin I/O control disabled
3
ADPC11
ADC Pin Control 11 — ADPC11 is used to control the pin associated with channel AD11.
0 AD11 pin I/O control enabled
1 AD11 pin I/O control disabled
2
ADPC10
ADC Pin Control 10 — ADPC10 is used to control the pin associated with channel AD10.
0 AD10 pin I/O control enabled
1 AD10 pin I/O control disabled
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Table 14-10. APCTL2 Register Field Descriptions (continued)
Field
Description
1
ADPC9
ADC Pin Control 9 — ADPC9 is used to control the pin associated with channel AD9.
0 AD9 pin I/O control enabled
1 AD9 pin I/O control disabled
0
ADPC8
ADC Pin Control 8 — ADPC8 is used to control the pin associated with channel AD8.
0 AD8 pin I/O control enabled
1 AD8 pin I/O control disabled
14.4.10 Pin Control 3 Register (APCTL3)
APCTL3 is used to control channels 16–23 of the ADC module.
7
6
5
4
3
2
1
0
ADPC23
ADPC22
ADPC21
ADPC20
ADPC19
ADPC18
ADPC17
ADPC16
0
0
0
0
0
0
0
0
R
W
Reset:
Figure 14-13. Pin Control 3 Register (APCTL3)
Table 14-11. APCTL3 Register Field Descriptions
Field
Description
7
ADPC23
ADC Pin Control 23 — ADPC23 is used to control the pin associated with channel AD23.
0 AD23 pin I/O control enabled
1 AD23 pin I/O control disabled
6
ADPC22
ADC Pin Control 22 — ADPC22 is used to control the pin associated with channel AD22.
0 AD22 pin I/O control enabled
1 AD22 pin I/O control disabled
5
ADPC21
ADC Pin Control 21 — ADPC21 is used to control the pin associated with channel AD21.
0 AD21 pin I/O control enabled
1 AD21 pin I/O control disabled
4
ADPC20
ADC Pin Control 20 — ADPC20 is used to control the pin associated with channel AD20.
0 AD20 pin I/O control enabled
1 AD20 pin I/O control disabled
3
ADPC19
ADC Pin Control 19 — ADPC19 is used to control the pin associated with channel AD19.
0 AD19 pin I/O control enabled
1 AD19 pin I/O control disabled
2
ADPC18
ADC Pin Control 18 — ADPC18 is used to control the pin associated with channel AD18.
0 AD18 pin I/O control enabled
1 AD18 pin I/O control disabled
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Table 14-11. APCTL3 Register Field Descriptions (continued)
Field
Description
1
ADPC17
ADC Pin Control 17 — ADPC17 is used to control the pin associated with channel AD17.
0 AD17 pin I/O control enabled
1 AD17 pin I/O control disabled
0
ADPC16
ADC Pin Control 16 — ADPC16 is used to control the pin associated with channel AD16.
0 AD16 pin I/O control enabled
1 AD16 pin I/O control disabled
14.5
Functional Description
The ADC module is disabled during reset or when the ADCH bits are all high. The module is idle when a
conversion has completed and another conversion has not been initiated. When idle, the module is in its
lowest power state.
The ADC can perform an analog-to-digital conversion on any of the software selectable channels. The
selected channel voltage is converted by a successive approximation algorithm into an 11-bit digital result.
In 8-bit mode, the selected channel voltage is converted by a successive approximation algorithm into a
9-bit digital result.
When the conversion is completed, the result is placed in the data registers (ADC1RH and ADC1RL).In
10-bit mode, the result is rounded to 10 bits and placed in ADC1RH and ADC1RL. In 8-bit mode, the
result is rounded to 8 bits and placed in ADC1RL. The conversion complete flag (COCO) is then set and
an interrupt is generated if the conversion complete interrupt has been enabled (AIEN = 1).
The ADC module has the capability of automatically comparing the result of a conversion with the
contents of its compare registers. The compare function is enabled by setting the ACFE bit and operates
in conjunction with any of the conversion modes and configurations.
14.5.1
Clock Select and Divide Control
One of four clock sources can be selected as the clock source for the ADC module. This clock source is
then divided by a configurable value to generate the input clock to the converter (ADCK). The clock is
selected from one of the following sources by means of the ADICLK bits.
•
•
•
•
The bus clock, which is equal to the frequency at which software is executed. This is the default
selection following reset.
The bus clock divided by 2. For higher bus clock rates, this allows a maximum divide by 16 of the
bus clock.
ALTCLK, as defined for this MCU (See module section introduction).
The asynchronous clock (ADACK) – This clock is generated from a clock source within the ADC
module. When selected as the clock source this clock remains active while the MCU is in wait or
stop3 mode and allows conversions in these modes for lower noise operation.
Whichever clock is selected, its frequency must fall within the specified frequency range for ADCK. If the
available clocks are too slow, the ADC will not perform according to specifications. If the available clocks
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are too fast, then the clock must be divided to the appropriate frequency. This divider is specified by the
ADIV bits and can be divide-by 1, 2, 4, or 8.
14.5.2
Input Select and Pin Control
The pin control registers (APCTL3, APCTL2, and APCTL1) are used to disable the I/O port control of the
pins used as analog inputs.When a pin control register bit is set, the following conditions are forced for the
associated MCU pin:
• The output buffer is forced to its high impedance state.
• The input buffer is disabled. A read of the I/O port returns a zero for any pin with its input buffer
disabled.
• The pullup is disabled.
14.5.3
Hardware Trigger
The ADC module has a selectable asynchronous hardware conversion trigger, ADHWT, that is enabled
when the ADTRG bit is set. This source is not available on all MCUs. Consult the module introduction for
information on the ADHWT source specific to this MCU.
When ADHWT source is available and hardware trigger is enabled (ADTRG=1), a conversion is initiated
on the rising edge of ADHWT. If a conversion is in progress when a rising edge occurs, the rising edge is
ignored. In continuous convert configuration, only the initial rising edge to launch continuous conversions
is observed. The hardware trigger function operates in conjunction with any of the conversion modes and
configurations.
14.5.4
Conversion Control
Conversions can be performed in either 10-bit mode or 8-bit mode as determined by the MODE bits.
Conversions can be initiated by either a software or hardware trigger. In addition, the ADC module can be
configured for low power operation, long sample time, continuous conversion, and automatic compare of
the conversion result to a software determined compare value.
14.5.4.1
Initiating Conversions
A conversion is initiated:
• Following a write to ADC1SC1 (with ADCH bits not all 1s) if software triggered operation is
selected.
• Following a hardware trigger (ADHWT) event if hardware triggered operation is selected.
• Following the transfer of the result to the data registers when continuous conversion is enabled.
If continuous conversions are enabled a new conversion is automatically initiated after the completion of
the current conversion. In software triggered operation, continuous conversions begin after ADC1SC1 is
written and continue until aborted. In hardware triggered operation, continuous conversions begin after a
hardware trigger event and continue until aborted.
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14.5.4.2
Completing Conversions
A conversion is completed when the result of the conversion is transferred into the data result registers,
ADC1RH and ADC1RL. This is indicated by the setting of COCO. An interrupt is generated if AIEN is
high at the time that COCO is set.
A blocking mechanism prevents a new result from overwriting previous data in ADC1RH and ADC1RL
if the previous data is in the process of being read while in 10-bit MODE (the ADC1RH register has been
read but the ADC1RL register has not). When blocking is active, the data transfer is blocked, COCO is not
set, and the new result is lost. In the case of single conversions with the compare function enabled and the
compare condition false, blocking has no effect and ADC operation is terminated. In all other cases of
operation, when a data transfer is blocked, another conversion is initiated regardless of the state of ADCO
(single or continuous conversions enabled).
If single conversions are enabled, the blocking mechanism could result in several discarded conversions
and excess power consumption. To avoid this issue, the data registers must not be read after initiating a
single conversion until the conversion completes.
14.5.4.3
Aborting Conversions
Any conversion in progress will be aborted when:
•
A write to ADC1SC1 occurs (the current conversion will be aborted and a new conversion will be
initiated, if ADCH are not all 1s).
•
A write to ADC1SC2, ADC1CFG, ADC1CVH, or ADC1CVL occurs. This indicates a mode of
operation change has occurred and the current conversion is therefore invalid.
•
The MCU is reset.
•
The MCU enters stop mode with ADACK not enabled.
When a conversion is aborted, the contents of the data registers, ADC1RH and ADC1RL, are not altered
but continue to be the values transferred after the completion of the last successful conversion. In the case
that the conversion was aborted by a reset, ADC1RH and ADC1RL return to their reset states.
14.5.4.4
Power Control
The ADC module remains in its idle state until a conversion is initiated. If ADACK is selected as the
conversion clock source, the ADACK clock generator is also enabled.
Power consumption when active can be reduced by setting ADLPC. This results in a lower maximum value
for fADCK (see the electrical specifications).
14.5.4.5
Total Conversion Time
The total conversion time depends on the sample time (as determined by ADLSMP), the MCU bus
frequency, the conversion mode (8-bit or 10-bit), and the frequency of the conversion clock (fADCK). After
the module becomes active, sampling of the input begins. ADLSMP is used to select between short and
long sample times.When sampling is complete, the converter is isolated from the input channel and a
successive approximation algorithm is performed to determine the digital value of the analog signal. The
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result of the conversion is transferred to ADC1RH and ADC1RL upon completion of the conversion
algorithm.
If the bus frequency is less than the fADCK frequency, precise sample time for continuous conversions
cannot be guaranteed when short sample is enabled (ADLSMP=0). If the bus frequency is less than 1/11th
of the fADCK frequency, precise sample time for continuous conversions cannot be guaranteed when long
sample is enabled (ADLSMP=1).
The maximum total conversion time for different conditions is summarized in Table 14-12.
Table 14-12. Total Conversion Time vs. Control Conditions
Conversion Type
ADICLK
ADLSMP
Max Total Conversion Time
Single or first continuous 8-bit
0x, 10
0
20 ADCK cycles + 5 bus clock cycles
Single or first continuous 10-bit
0x, 10
0
23 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit
0x, 10
1
40 ADCK cycles + 5 bus clock cycles
Single or first continuous 10-bit
0x, 10
1
43 ADCK cycles + 5 bus clock cycles
Single or first continuous 8-bit
11
0
5 μs + 20 ADCK + 5 bus clock cycles
Single or first continuous 10-bit
11
0
5 μs + 23 ADCK + 5 bus clock cycles
Single or first continuous 8-bit
11
1
5 μs + 40 ADCK + 5 bus clock cycles
Single or first continuous 10-bit
11
1
5 μs + 43 ADCK + 5 bus clock cycles
Subsequent continuous 8-bit;
fBUS > fADCK
xx
0
17 ADCK cycles
Subsequent continuous 10-bit;
fBUS > fADCK
xx
0
20 ADCK cycles
Subsequent continuous 8-bit;
fBUS > fADCK/11
xx
1
37 ADCK cycles
Subsequent continuous 10-bit;
fBUS > fADCK/11
xx
1
40 ADCK cycles
The maximum total conversion time is determined by the clock source chosen and the divide ratio selected.
The clock source is selectable by the ADICLK bits, and the divide ratio is specified by the ADIV bits. For
example, in 10-bit mode, with the bus clock selected as the input clock source, the input clock divide-by-1
ratio selected, and a bus frequency of 8 MHz, then the conversion time for a single conversion is:
Conversion time =
23 ADCK cyc
8 MHz/1
+
5 bus cyc
8 MHz
= 3.5 μs
Number of bus cycles = 3.5 μs x 8 MHz = 28 cycles
NOTE
The ADCK frequency must be between fADCK minimum and fADCK
maximum to meet ADC specifications.
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14.5.5
Automatic Compare Function
The compare function can be configured to check for either an upper limit or lower limit. After the input
is sampled and converted, the result is added to the two’s complement of the compare value (ADC1CVH
and ADC1CVL). When comparing to an upper limit (ACFGT = 1), if the result is greater-than or equal-to
the compare value, COCO is set. When comparing to a lower limit (ACFGT = 0), if the result is less than
the compare value, COCO is set. The value generated by the addition of the conversion result and the two’s
complement of the compare value is transferred to ADC1RH and ADC1RL.
Upon completion of a conversion while the compare function is enabled, if the compare condition is not
true, COCO is not set and no data is transferred to the result registers. An ADC interrupt is generated upon
the setting of COCO if the ADC interrupt is enabled (AIEN = 1).
NOTE
The compare function can be used to monitor the voltage on a channel while
the MCU is in either wait or stop3 mode. The ADC interrupt will wake the
MCU when the compare condition is met.
14.5.6
MCU Wait Mode Operation
The WAIT instruction puts the MCU in a lower power-consumption standby mode from which recovery
is very fast because the clock sources remain active. If a conversion is in progress when the MCU enters
wait mode, it continues until completion. Conversions can be initiated while the MCU is in wait mode by
means of the hardware trigger or if continuous conversions are enabled.
The bus clock, bus clock divided by two, and ADACK are available as conversion clock sources while in
wait mode. The use of ALTCLK as the conversion clock source in wait is dependent on the definition of
ALTCLK for this MCU. Consult the module introduction for information on ALTCLK specific to this
MCU.
A conversion complete event sets the COCO and generates an ADC interrupt to wake the MCU from wait
mode if the ADC interrupt is enabled (AIEN = 1).
14.5.7
MCU Stop3 Mode Operation
The STOP instruction is used to put the MCU in a low power-consumption standby mode during which
most or all clock sources on the MCU are disabled.
14.5.7.1
Stop3 Mode With ADACK Disabled
If the asynchronous clock, ADACK, is not selected as the conversion clock, executing a STOP instruction
aborts the current conversion and places the ADC in its idle state. The contents of ADC1RH and ADC1RL
are unaffected by stop3 mode.After exiting from stop3 mode, a software or hardware trigger is required to
resume conversions.
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14.5.7.2
Stop3 Mode With ADACK Enabled
If ADACK is selected as the conversion clock, the ADC continues operation during stop3 mode. For
guaranteed ADC operation, the MCU’s voltage regulator must remain active during stop3 mode. Consult
the module introduction for configuration information for this MCU.
If a conversion is in progress when the MCU enters stop3 mode, it continues until completion. Conversions
can be initiated while the MCU is in stop3 mode by means of the hardware trigger or if continuous
conversions are enabled.
A conversion complete event sets the COCO and generates an ADC interrupt to wake the MCU from stop3
mode if the ADC interrupt is enabled (AIEN = 1).
NOTE
It is possible for the ADC module to wake the system from low power stop
and cause the MCU to begin consuming run-level currents without
generating a system level interrupt. To prevent this scenario, software
should ensure that the data transfer blocking mechanism (discussed in
Section 14.5.4.2, “Completing Conversions) is cleared when entering stop3
and continuing ADC conversions.
14.5.8
MCU Stop1 and Stop2 Mode Operation
The ADC module is automatically disabled when the MCU enters either stop1 or stop2 mode. All module
registers contain their reset values following exit from stop1 or stop2. Therefore the module must be
re-enabled and re-configured following exit from stop1 or stop2.
14.6
Initialization Information
This section gives an example which provides some basic direction on how a user would initialize and
configure the ADC module. The user has the flexibility of choosing between configuring the module for
8-bit or 10-bit resolution, single or continuous conversion, and a polled or interrupt approach, among many
other options. Refer to Table 14-6, Table 14-7, and Table 14-8 for information used in this example.
NOTE
Hexadecimal values designated by a preceding 0x, binary values designated
by a preceding %, and decimal values have no preceding character.
14.6.1
14.6.1.1
ADC Module Initialization Example
Initialization Sequence
Before the ADC module can be used to complete conversions, an initialization procedure must be
performed. A typical sequence is as follows:
1. Update the configuration register (ADCCFG) to select the input clock source and the divide ratio
used to generate the internal clock, ADCK. This register is also used for selecting sample time and
low-power configuration.
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2. Update status and control register 2 (ADCSC2) to select the conversion trigger (hardware or
software) and compare function options, if enabled.
3. Update status and control register 1 (ADCSC1) to select whether conversions will be continuous
or completed only once, and to enable or disable conversion complete interrupts. The input channel
on which conversions will be performed is also selected here.
14.6.1.2
Pseudo — Code Example
In this example, the ADC module will be set up with interrupts enabled to perform a single 10-bit
conversion at low power with a long sample time on input channel 1, where the internal ADCK clock will
be derived from the bus clock divided by 1.
ADCCFG = 0x98 (%10011000)
Bit 7
ADLPC
1
Configures for low power (lowers maximum clock speed)
Bit 6:5 ADIV
00
Sets the ADCK to the input clock ÷ 1
Bit 4
ADLSMP 1
Configures for long sample time
Bit 3:2 MODE
10
Sets mode at 10-bit conversions
Bit 1:0 ADICLK 00
Selects bus clock as input clock source
ADCSC2 = 0x00 (%00000000)
Bit 7
ADACT
0
Bit 6
ADTRG
0
Bit 5
ACFE
0
Bit 4
ACFGT
0
Bit 3:2
00
Bit 1:0
00
Flag indicates if a conversion is in progress
Software trigger selected
Compare function disabled
Not used in this example
Unimplemented or reserved, always reads zero
Reserved for Freescale’s internal use; always write zero
ADCSC1 = 0x41 (%01000001)
Bit 7
COCO
0
Bit 6
AIEN
1
Bit 5
ADCO
0
Bit 4:0 ADCH
00001
Read-only flag which is set when a conversion completes
Conversion complete interrupt enabled
One conversion only (continuous conversions disabled)
Input channel 1 selected as ADC input channel
ADCRH/L = 0xxx
Holds results of conversion. Read high byte (ADCRH) before low byte (ADCRL) so that conversion
data cannot be overwritten with data from the next conversion.
ADCCVH/L = 0xxx
Holds compare value when compare function enabled
APCTL1=0x02
AD1 pin I/O control disabled. All other AD pins remain general purpose I/O pins
APCTL2=0x00
All other AD pins remain general purpose I/O pins
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RESET
INITIALIZE ADC
ADCCFG = $98
ADCSC2 = $00
ADCSC1 = $41
CHECK
COCO=1?
NO
YES
READ ADCRH
THEN ADCRL TO
CLEAR COCO BIT
CONTINUE
Figure 14-14. Initialization Flowchart for Example
14.7
Application Information
This section contains information for using the ADC module in applications. The ADC has been designed
to be integrated into a microcontroller for use in embedded control applications requiring an A/D
converter.
14.7.1
External Pins and Routing
The following sections discuss the external pins associated with the ADC module and how they should be
used for best results.
14.7.1.1
Analog Supply Pins
The ADC module has analog power and ground supplies (VDDAD and VSSAD) which are available as
separate pins on some devices. On other devices, VSSAD is shared on the same pin as the MCU digital VSS,
and on others, both VSSAD and VDDAD are shared with the MCU digital supply pins. In these cases, there
are separate pads for the analog supplies which are bonded to the same pin as the corresponding digital
supply so that some degree of isolation between the supplies is maintained.
When available on a separate pin, both VDDAD and VSSAD must be connected to the same voltage potential
as their corresponding MCU digital supply (VDD and VSS) and must be routed carefully for maximum
noise immunity and bypass capacitors placed as near as possible to the package.
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In cases where separate power supplies are used for analog and digital power, the ground connection
between these supplies must be at the VSSAD pin. This should be the only ground connection between these
supplies if possible. The VSSAD pin makes a good single point ground location.
14.7.1.2
Analog Reference Pins
In addition to the analog supplies, the ADC module has connections for two reference voltage inputs. The
high reference is VREFH, which may be shared on the same pin as VDDAD on some devices. The low
reference is VREFL, which may be shared on the same pin as VSSAD on some devices.
When available on a separate pin, VREFH may be connected to the same potential as VDDAD, or may be
driven by an external source that is between the minimum VDDAD spec and the VDDAD potential (VREFH
must never exceed VDDAD). When available on a separate pin, VREFL must be connected to the same
voltage potential as VSSAD. Both VREFH and VREFL must be routed carefully for maximum noise
immunity and bypass capacitors placed as near as possible to the package.
AC current in the form of current spikes required to supply charge to the capacitor array at each successive
approximation step is drawn through the VREFH and VREFL loop. The best external component to meet this
current demand is a 0.1 μF capacitor with good high frequency characteristics. This capacitor is connected
between VREFH and VREFL and must be placed as near as possible to the package pins. Resistance in the
path is not recommended because the current will cause a voltage drop which could result in conversion
errors. Inductance in this path must be minimum (parasitic only).
14.7.1.3
Analog Input Pins
The external analog inputs are typically shared with digital I/O pins on MCU devices. The pin I/O control
is disabled by setting the appropriate control bit in one of the pin control registers. Conversions can be
performed on inputs without the associated pin control register bit set. It is recommended that the pin
control register bit always be set when using a pin as an analog input. This avoids problems with contention
because the output buffer will be in its high impedance state and the pullup is disabled. Also, the input
buffer draws dc current when its input is not at either VDD or VSS. Setting the pin control register bits for
all pins used as analog inputs should be done to achieve lowest operating current.
Empirical data shows that capacitors on the analog inputs improve performance in the presence of noise
or when the source impedance is high. Use of 0.01 μF capacitors with good high-frequency characteristics
is sufficient. These capacitors are not necessary in all cases, but when used they must be placed as near as
possible to the package pins and be referenced to VSSA.
For proper conversion, the input voltage must fall between VREFH and VREFL. If the input is equal to or
exceeds VREFH, the converter circuit converts the signal to $3FF (full scale 10-bit representation) or $FF
(full scale 8-bit representation). If the input is equal to or less than VREFL, the converter circuit converts it
to $000. Input voltages between VREFH and VREFL are straight-line linear conversions. There will be a
brief current associated with VREFL when the sampling capacitor is charging. The input is sampled for
3.5 cycles of the ADCK source when ADLSMP is low, or 23.5 cycles when ADLSMP is high.
For minimal loss of accuracy due to current injection, pins adjacent to the analog input pins should not be
transitioning during conversions.
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14.7.2
Sources of Error
Several sources of error exist for A/D conversions. These are discussed in the following sections.
14.7.2.1
Sampling Error
For proper conversions, the input must be sampled long enough to achieve the proper accuracy. Given the
maximum input resistance of approximately 7kΩ and input capacitance of approximately 5.5 pF, sampling
to within 1/4LSB (at 10-bit resolution) can be achieved within the minimum sample window (3.5 cycles @
8 MHz maximum ADCK frequency) provided the resistance of the external analog source (RAS) is kept
below 5 kΩ.
Higher source resistances or higher-accuracy sampling is possible by setting ADLSMP (to increase the
sample window to 23.5 cycles) or decreasing ADCK frequency to increase sample time.
14.7.2.2
Pin Leakage Error
Leakage on the I/O pins can cause conversion error if the external analog source resistance (RAS) is high.
If this error cannot be tolerated by the application, keep RAS lower than VDDAD / (2N*ILEAK) for less than
1/4LSB leakage error (N = 8 in 8-bit mode or 10 in 10-bit mode).
14.7.2.3
Noise-Induced Errors
System noise which occurs during the sample or conversion process can affect the accuracy of the
conversion. The ADC accuracy numbers are guaranteed as specified only if the following conditions are
met:
• There is a 0.1 μF low-ESR capacitor from VREFH to VREFL.
• There is a 0.1 μF low-ESR capacitor from VDDAD to VSSAD.
• If inductive isolation is used from the primary supply, an additional 1 μF capacitor is placed from
VDDAD to VSSAD.
• VSSAD (and VREFL, if connected) is connected to VSS at a quiet point in the ground plane.
• Operate the MCU in wait or stop3 mode before initiating (hardware triggered conversions) or
immediately after initiating (hardware or software triggered conversions) the ADC conversion.
— For software triggered conversions, immediately follow the write to the ADC1SC1 with a
WAIT instruction or STOP instruction.
— For stop3 mode operation, select ADACK as the clock source. Operation in stop3 reduces VDD
noise but increases effective conversion time due to stop recovery.
• There is no I/O switching, input or output, on the MCU during the conversion.
There are some situations where external system activity causes radiated or conducted noise emissions or
excessive VDD noise is coupled into the ADC. In these situations, or when the MCU cannot be placed in
wait or stop3 or I/O activity cannot be halted, these recommended actions may reduce the effect of noise
on the accuracy:
• Place a 0.01 μF capacitor (CAS) on the selected input channel to VREFL or VSSAD (this will
improve noise issues but will affect sample rate based on the external analog source resistance).
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•
•
Average the result by converting the analog input many times in succession and dividing the sum
of the results. Four samples are required to eliminate the effect of a 1LSB, one-time error.
Reduce the effect of synchronous noise by operating off the asynchronous clock (ADACK) and
averaging. Noise that is synchronous to ADCK cannot be averaged out.
14.7.2.4
Code Width and Quantization Error
The ADC quantizes the ideal straight-line transfer function into 1024 steps (in 10-bit mode). Each step
ideally has the same height (1 code) and width. The width is defined as the delta between the transition
points to one code and the next. The ideal code width for an N bit converter (in this case N can be 8 or 10),
defined as 1LSB, is:
1LSB = (VREFH - VREFL) / 2N
Eqn. 14-2
There is an inherent quantization error due to the digitization of the result. For 8-bit or 10-bit conversions
the code will transition when the voltage is at the midpoint between the points where the straight line
transfer function is exactly represented by the actual transfer function. Therefore, the quantization error
will be ± 1/2LSB in 8- or 10-bit mode. As a consequence, however, the code width of the first ($000)
conversion is only 1/2LSB and the code width of the last ($FF or $3FF) is 1.5LSB.
14.7.2.5
Linearity Errors
The ADC may also exhibit non-linearity of several forms. Every effort has been made to reduce these
errors but the system should be aware of them because they affect overall accuracy. These errors are:
• Zero-scale error (EZS) (sometimes called offset) — This error is defined as the difference between
the actual code width of the first conversion and the ideal code width (1/2LSB). Note, if the first
conversion is $001, then the difference between the actual $001 code width and its ideal (1LSB) is
used.
• Full-scale error (EFS) — This error is defined as the difference between the actual code width of
the last conversion and the ideal code width (1.5LSB). Note, if the last conversion is $3FE, then the
difference between the actual $3FE code width and its ideal (1LSB) is used.
• Differential non-linearity (DNL) — This error is defined as the worst-case difference between the
actual code width and the ideal code width for all conversions.
• Integral non-linearity (INL) — This error is defined as the highest-value the (absolute value of the)
running sum of DNL achieves. More simply, this is the worst-case difference of the actual
transition voltage to a given code and its corresponding ideal transition voltage, for all codes.
• Total unadjusted error (TUE) — This error is defined as the difference between the actual transfer
function and the ideal straight-line transfer function, and therefore includes all forms of error.
14.7.2.6
Code Jitter, Non-Monotonicity and Missing Codes
Analog-to-digital converters are susceptible to three special forms of error. These are code jitter,
non-monotonicity, and missing codes.
Code jitter is when, at certain points, a given input voltage converts to one of two values when sampled
repeatedly. Ideally, when the input voltage is infinitesimally smaller than the transition voltage, the
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converter yields the lower code (and vice-versa). However, even very small amounts of system noise can
cause the converter to be indeterminate (between two codes) for a range of input voltages around the
transition voltage. This range is normally around 1/2LSB and will increase with noise. This error may be
reduced by repeatedly sampling the input and averaging the result. Additionally the techniques discussed
in Section 14.7.2.3 will reduce this error.
Non-monotonicity is defined as when, except for code jitter, the converter converts to a lower code for a
higher input voltage. Missing codes are those values which are never converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and to have no missing codes.
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Chapter 15
Development Support
15.1
Introduction
Development support systems in the HCS08 include the background debug controller (BDC) and the
on-chip debug module (DBG). The BDC provides a single-wire debug interface to the target MCU that
provides a convenient interface for programming the on-chip FLASH and other nonvolatile memories. The
BDC is also the primary debug interface for development and allows non-intrusive access to memory data
and traditional debug features such as CPU register modify, breakpoints, and single instruction trace
commands.
In the HCS08 Family, address and data bus signals are not available on external pins (not even in test
modes). Debug is done through commands fed into the target MCU via the single-wire background debug
interface. The debug module provides a means to selectively trigger and capture bus information so an
external development system can reconstruct what happened inside the MCU on a cycle-by-cycle basis
without having external access to the address and data signals.
The alternate BDC clock source for MC9S08AC16 Series is the ICGLCLK. See Chapter 8, “Internal
Clock Generator (S08ICGV4)” for more information about ICGCLK and how to select clock sources.
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15.1.1
Features
Features of the BDC module include:
• Single pin for mode selection and background communications
• BDC registers are not located in the memory map
• SYNC command to determine target communications rate
• Non-intrusive commands for memory access
• Active background mode commands for CPU register access
• GO and TRACE1 commands
• BACKGROUND command can wake CPU from stop or wait modes
• One hardware address breakpoint built into BDC
• Oscillator runs in stop mode, if BDC enabled
• COP watchdog disabled while in active background mode
Features of the ICE system include:
•
•
•
•
15.2
Two trigger comparators: Two address + read/write (R/W) or one full address + data + R/W
Flexible 8-word by 16-bit FIFO (first-in, first-out) buffer for capture information:
— Change-of-flow addresses or
— Event-only data
Two types of breakpoints:
— Tag breakpoints for instruction opcodes
— Force breakpoints for any address access
Nine trigger modes:
— Basic: A-only, A OR B
— Sequence: A then B
— Full: A AND B data, A AND NOT B data
— Event (store data): Event-only B, A then event-only B
— Range: Inside range (A ≤ address ≤ B), outside range (address < A or address > B)
Background Debug Controller (BDC)
All MCUs in the HCS08 Family contain a single-wire background debug interface that supports in-circuit
programming of on-chip nonvolatile memory and sophisticated non-intrusive debug capabilities. Unlike
debug interfaces on earlier 8-bit MCUs, this system does not interfere with normal application resources.
It does not use any user memory or locations in the memory map and does not share any on-chip
peripherals.
BDC commands are divided into two groups:
• Active background mode commands require that the target MCU is in active background mode (the
user program is not running). Active background mode commands allow the CPU registers to be
read or written, and allow the user to trace one user instruction at a time, or GO to the user program
from active background mode.
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•
Non-intrusive commands can be executed at any time even while the user’s program is running.
Non-intrusive commands allow a user to read or write MCU memory locations or access status and
control registers within the background debug controller.
Typically, a relatively simple interface pod is used to translate commands from a host computer into
commands for the custom serial interface to the single-wire background debug system. Depending on the
development tool vendor, this interface pod may use a standard RS-232 serial port, a parallel printer port,
or some other type of communications such as a universal serial bus (USB) to communicate between the
host PC and the pod. The pod typically connects to the target system with ground, the BKGD pin, RESET,
and sometimes VDD. An open-drain connection to reset allows the host to force a target system reset,
which is useful to regain control of a lost target system or to control startup of a target system before the
on-chip nonvolatile memory has been programmed. Sometimes VDD can be used to allow the pod to use
power from the target system to avoid the need for a separate power supply. However, if the pod is powered
separately, it can be connected to a running target system without forcing a target system reset or otherwise
disturbing the running application program.
BKGD 1
2 GND
NO CONNECT 3
4 RESET
NO CONNECT 5
6 VDD
Figure 15-1. BDM Tool Connector
15.2.1
BKGD Pin Description
BKGD is the single-wire background debug interface pin. The primary function of this pin is for
bidirectional serial communication of active background mode commands and data. During reset, this pin
is used to select between starting in active background mode or starting the user’s application program.
This pin is also used to request a timed sync response pulse to allow a host development tool to determine
the correct clock frequency for background debug serial communications.
BDC serial communications use a custom serial protocol first introduced on the M68HC12 Family of
microcontrollers. This protocol assumes the host knows the communication clock rate that is determined
by the target BDC clock rate. All communication is initiated and controlled by the host that drives a
high-to-low edge to signal the beginning of each bit time. Commands and data are sent most significant bit
first (MSB first). For a detailed description of the communications protocol, refer to Section 15.2.2,
“Communication Details.”
If a host is attempting to communicate with a target MCU that has an unknown BDC clock rate, a SYNC
command may be sent to the target MCU to request a timed sync response signal from which the host can
determine the correct communication speed.
BKGD is a pseudo-open-drain pin and there is an on-chip pullup so no external pullup resistor is required.
Unlike typical open-drain pins, the external RC time constant on this pin, which is influenced by external
capacitance, plays almost no role in signal rise time. The custom protocol provides for brief, actively
driven speedup pulses to force rapid rise times on this pin without risking harmful drive level conflicts.
Refer to Section 15.2.2, “Communication Details,” for more detail.
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When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD
chooses normal operating mode. When a debug pod is connected to BKGD it is possible to force the MCU
into active background mode after reset. The specific conditions for forcing active background depend
upon the HCS08 derivative (refer to the introduction to this Development Support section). It is not
necessary to reset the target MCU to communicate with it through the background debug interface.
15.2.2
Communication Details
The BDC serial interface requires the external controller to generate a falling edge on the BKGD pin to
indicate the start of each bit time. The external controller provides this falling edge whether data is
transmitted or received.
BKGD is a pseudo-open-drain pin that can be driven either by an external controller or by the MCU. Data
is transferred MSB first at 16 BDC clock cycles per bit (nominal speed). The interface times out if
512 BDC clock cycles occur between falling edges from the host. Any BDC command that was in progress
when this timeout occurs is aborted without affecting the memory or operating mode of the target MCU
system.
The custom serial protocol requires the debug pod to know the target BDC communication clock speed.
The clock switch (CLKSW) control bit in the BDC status and control register allows the user to select the
BDC clock source. The BDC clock source can either be the bus or the alternate BDC clock source.
The BKGD pin can receive a high or low level or transmit a high or low level. The following diagrams
show timing for each of these cases. Interface timing is synchronous to clocks in the target BDC, but
asynchronous to the external host. The internal BDC clock signal is shown for reference in counting cycles.
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Figure 15-2 shows an external host transmitting a logic 1 or 0 to the BKGD pin of a target HCS08 MCU.
The host is asynchronous to the target so there is a 0-to-1 cycle delay from the host-generated falling edge
to where the target perceives the beginning of the bit time. Ten target BDC clock cycles later, the target
senses the bit level on the BKGD pin. Typically, the host actively drives the pseudo-open-drain BKGD pin
during host-to-target transmissions to speed up rising edges. Because the target does not drive the BKGD
pin during the host-to-target transmission period, there is no need to treat the line as an open-drain signal
during this period.
BDC CLOCK
(TARGET MCU)
HOST
TRANSMIT 1
HOST
TRANSMIT 0
10 CYCLES
SYNCHRONIZATION
UNCERTAINTY
EARLIEST START
OF NEXT BIT
TARGET SENSES BIT LEVEL
PERCEIVED START
OF BIT TIME
Figure 15-2. BDC Host-to-Target Serial Bit Timing
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Figure 15-3 shows the host receiving a logic 1 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the perceived start of the bit time in the target MCU. The host holds the BKGD pin low long
enough for the target to recognize it (at least two target BDC cycles). The host must release the low drive
before the target MCU drives a brief active-high speedup pulse seven cycles after the perceived start of the
bit time. The host should sample the bit level about 10 cycles after it started the bit time.
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
HIGH-IMPEDANCE
TARGET MCU
SPEEDUP PULSE
HIGH-IMPEDANCE
HIGH-IMPEDANCE
PERCEIVED START
OF BIT TIME
R-C RISE
BKGD PIN
10 CYCLES
10 CYCLES
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
Figure 15-3. BDC Target-to-Host Serial Bit Timing (Logic 1)
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Figure 15-4 shows the host receiving a logic 0 from the target HCS08 MCU. Because the host is
asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on
BKGD to the start of the bit time as perceived by the target MCU. The host initiates the bit time but the
target HCS08 finishes it. Because the target wants the host to receive a logic 0, it drives the BKGD pin low
for 13 BDC clock cycles, then briefly drives it high to speed up the rising edge. The host samples the bit
level about 10 cycles after starting the bit time.
BDC CLOCK
(TARGET MCU)
HOST DRIVE
TO BKGD PIN
HIGH-IMPEDANCE
SPEEDUP
PULSE
TARGET MCU
DRIVE AND
SPEED-UP PULSE
PERCEIVED START
OF BIT TIME
BKGD PIN
10 CYCLES
10 CYCLES
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
Figure 15-4. BDM Target-to-Host Serial Bit Timing (Logic 0)
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15.2.3
BDC Commands
BDC commands are sent serially from a host computer to the BKGD pin of the target HCS08 MCU. All
commands and data are sent MSB-first using a custom BDC communications protocol. Active background
mode commands require that the target MCU is currently in the active background mode while
non-intrusive commands may be issued at any time whether the target MCU is in active background mode
or running a user application program.
Table 15-1 shows all HCS08 BDC commands, a shorthand description of their coding structure, and the
meaning of each command.
Coding Structure Nomenclature
This nomenclature is used in Table 15-1 to describe the coding structure of the BDC commands.
Commands begin with an 8-bit hexadecimal command code in the host-to-target
direction (most significant bit first)
/ = separates parts of the command
d = delay 16 target BDC clock cycles
AAAA = a 16-bit address in the host-to-target direction
RD = 8 bits of read data in the target-to-host direction
WD = 8 bits of write data in the host-to-target direction
RD16 = 16 bits of read data in the target-to-host direction
WD16 = 16 bits of write data in the host-to-target direction
SS = the contents of BDCSCR in the target-to-host direction (STATUS)
CC = 8 bits of write data for BDCSCR in the host-to-target direction (CONTROL)
RBKP = 16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint
register)
WBKP = 16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register)
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Table 15-1. BDC Command Summary
Command
Mnemonic
1
Active BDM/
Non-intrusive
Coding
Structure
Description
SYNC
Non-intrusive
n/a1
Request a timed reference pulse to determine
target BDC communication speed
ACK_ENABLE
Non-intrusive
D5/d
Enable acknowledge protocol. Refer to
Freescale document order no. HCS08RMv1/D.
ACK_DISABLE
Non-intrusive
D6/d
Disable acknowledge protocol. Refer to
Freescale document order no. HCS08RMv1/D.
BACKGROUND
Non-intrusive
90/d
Enter active background mode if enabled
(ignore if ENBDM bit equals 0)
READ_STATUS
Non-intrusive
E4/SS
Read BDC status from BDCSCR
WRITE_CONTROL
Non-intrusive
C4/CC
Write BDC controls in BDCSCR
READ_BYTE
Non-intrusive
E0/AAAA/d/RD
Read a byte from target memory
READ_BYTE_WS
Non-intrusive
E1/AAAA/d/SS/RD
Read a byte and report status
READ_LAST
Non-intrusive
E8/SS/RD
Re-read byte from address just read and
report status
WRITE_BYTE
Non-intrusive
C0/AAAA/WD/d
Write a byte to target memory
WRITE_BYTE_WS
Non-intrusive
C1/AAAA/WD/d/SS
Write a byte and report status
READ_BKPT
Non-intrusive
E2/RBKP
Read BDCBKPT breakpoint register
WRITE_BKPT
Non-intrusive
C2/WBKP
Write BDCBKPT breakpoint register
GO
Active BDM
08/d
Go to execute the user application program
starting at the address currently in the PC
TRACE1
Active BDM
10/d
Trace 1 user instruction at the address in the
PC, then return to active background mode
TAGGO
Active BDM
18/d
Same as GO but enable external tagging
(HCS08 devices have no external tagging pin)
READ_A
Active BDM
68/d/RD
Read accumulator (A)
READ_CCR
Active BDM
69/d/RD
Read condition code register (CCR)
READ_PC
Active BDM
6B/d/RD16
Read program counter (PC)
READ_HX
Active BDM
6C/d/RD16
Read H and X register pair (H:X)
READ_SP
Active BDM
6F/d/RD16
Read stack pointer (SP)
READ_NEXT
Active BDM
70/d/RD
Increment H:X by one then read memory byte
located at H:X
READ_NEXT_WS
Active BDM
71/d/SS/RD
Increment H:X by one then read memory byte
located at H:X. Report status and data.
WRITE_A
Active BDM
48/WD/d
Write accumulator (A)
WRITE_CCR
Active BDM
49/WD/d
Write condition code register (CCR)
WRITE_PC
Active BDM
4B/WD16/d
Write program counter (PC)
WRITE_HX
Active BDM
4C/WD16/d
Write H and X register pair (H:X)
WRITE_SP
Active BDM
4F/WD16/d
Write stack pointer (SP)
WRITE_NEXT
Active BDM
50/WD/d
Increment H:X by one, then write memory byte
located at H:X
WRITE_NEXT_WS
Active BDM
51/WD/d/SS
Increment H:X by one, then write memory byte
located at H:X. Also report status.
The SYNC command is a special operation that does not have a command code.
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The SYNC command is unlike other BDC commands because the host does not necessarily know the
correct communications speed to use for BDC communications until after it has analyzed the response to
the SYNC command.
To issue a SYNC command, the host:
• Drives the BKGD pin low for at least 128 cycles of the slowest possible BDC clock (The slowest
clock is normally the reference oscillator/64 or the self-clocked rate/64.)
• Drives BKGD high for a brief speedup pulse to get a fast rise time (This speedup pulse is typically
one cycle of the fastest clock in the system.)
• Removes all drive to the BKGD pin so it reverts to high impedance
• Monitors the BKGD pin for the sync response pulse
The target, upon detecting the SYNC request from the host (which is a much longer low time than would
ever occur during normal BDC communications):
• Waits for BKGD to return to a logic high
• Delays 16 cycles to allow the host to stop driving the high speedup pulse
• Drives BKGD low for 128 BDC clock cycles
• Drives a 1-cycle high speedup pulse to force a fast rise time on BKGD
• 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 BDC 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.
15.2.4
BDC Hardware Breakpoint
The BDC includes one relatively simple hardware breakpoint that compares the CPU address bus to a
16-bit match value in the BDCBKPT register. This breakpoint can generate a forced breakpoint or a tagged
breakpoint. A forced breakpoint causes the CPU to enter active background mode at the first instruction
boundary following any access to the breakpoint address. The tagged breakpoint causes the instruction
opcode at the breakpoint address to be tagged so that the CPU will enter active background mode rather
than executing that instruction if and when it reaches the end of the instruction queue. This implies that
tagged breakpoints can only be placed at the address of an instruction opcode while forced breakpoints can
be set at any address.
The breakpoint enable (BKPTEN) control bit in the BDC status and control register (BDCSCR) is used to
enable the breakpoint logic (BKPTEN = 1). When BKPTEN = 0, its default value after reset, the
breakpoint logic is disabled and no BDC breakpoints are requested regardless of the values in other BDC
breakpoint registers and control bits. The force/tag select (FTS) control bit in BDCSCR is used to select
forced (FTS = 1) or tagged (FTS = 0) type breakpoints.
The on-chip debug module (DBG) includes circuitry for two additional hardware breakpoints that are more
flexible than the simple breakpoint in the BDC module.
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15.3
On-Chip Debug System (DBG)
Because HCS08 devices do not have external address and data buses, the most important functions of an
in-circuit emulator have been built onto the chip with the MCU. The debug system consists of an 8-stage
FIFO that can store address or data bus information, and a flexible trigger system to decide when to capture
bus information and what information to capture. The system relies on the single-wire background debug
system to access debug control registers and to read results out of the eight stage FIFO.
The debug module includes control and status registers that are accessible in the user’s memory map.
These registers are located in the high register space to avoid using valuable direct page memory space.
Most of the debug module’s functions are used during development, and user programs rarely access any
of the control and status registers for the debug module. The one exception is that the debug system can
provide the means to implement a form of ROM patching. This topic is discussed in greater detail in
Section 15.3.6, “Hardware Breakpoints.”
15.3.1
Comparators A and B
Two 16-bit comparators (A and B) can optionally be qualified with the R/W signal and an opcode tracking
circuit. Separate control bits allow you to ignore R/W for each comparator. The opcode tracking circuitry
optionally allows you to specify that a trigger will occur only if the opcode at the specified address is
actually executed as opposed to only being read from memory into the instruction queue. The comparators
are also capable of magnitude comparisons to support the inside range and outside range trigger modes.
Comparators are disabled temporarily during all BDC accesses.
The A comparator is always associated with the 16-bit CPU address. The B comparator compares to the
CPU address or the 8-bit CPU data bus, depending on the trigger mode selected. Because the CPU data
bus is separated into a read data bus and a write data bus, the RWAEN and RWA control bits have an
additional purpose, in full address plus data comparisons they are used to decide which of these buses to
use in the comparator B data bus comparisons. If RWAEN = 1 (enabled) and RWA = 0 (write), the CPU’s
write data bus is used. Otherwise, the CPU’s read data bus is used.
The currently selected trigger mode determines what the debugger logic does when a comparator detects
a qualified match condition. A match can cause:
• Generation of a breakpoint to the CPU
• Storage of data bus values into the FIFO
• Starting to store change-of-flow addresses into the FIFO (begin type trace)
• Stopping the storage of change-of-flow addresses into the FIFO (end type trace)
15.3.2
Bus Capture Information and FIFO Operation
The usual way to use the FIFO is to setup the trigger mode and other control options, then arm the
debugger. When the FIFO has filled or the debugger has stopped storing data into the FIFO, you would
read the information out of it in the order it was stored into the FIFO. Status bits indicate the number of
words of valid information that are in the FIFO as data is stored into it. If a trace run is manually halted by
writing 0 to ARM before the FIFO is full (CNT = 1:0:0:0), the information is shifted by one position and
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the host must perform ((8 – CNT) – 1) dummy reads of the FIFO to advance it to the first significant entry
in the FIFO.
In most trigger modes, the information stored in the FIFO consists of 16-bit change-of-flow addresses. In
these cases, read DBGFH then DBGFL to get one coherent word of information out of the FIFO. Reading
DBGFL (the low-order byte of the FIFO data port) causes the FIFO to shift so the next word of information
is available at the FIFO data port. In the event-only trigger modes (see Section 15.3.5, “Trigger Modes”),
8-bit data information is stored into the FIFO. In these cases, the high-order half of the FIFO (DBGFH) is
not used and data is read out of the FIFO by simply reading DBGFL. Each time DBGFL is read, the FIFO
is shifted so the next data value is available through the FIFO data port at DBGFL.
In trigger modes where the FIFO is storing change-of-flow addresses, there is a delay between CPU
addresses and the input side of the FIFO. Because of this delay, if the trigger event itself is a change-of-flow
address or a change-of-flow address appears during the next two bus cycles after a trigger event starts the
FIFO, it will not be saved into the FIFO. In the case of an end-trace, if the trigger event is a change-of-flow,
it will be saved as the last change-of-flow entry for that debug run.
The FIFO can also be used to generate a profile of executed instruction addresses when the debugger is not
armed. When ARM = 0, reading DBGFL causes the address of the most-recently fetched opcode to be
saved in the FIFO. To use the profiling feature, a host debugger would read addresses out of the FIFO by
reading DBGFH then DBGFL at regular periodic intervals. The first eight values would be discarded
because they correspond to the eight DBGFL reads needed to initially fill the FIFO. Additional periodic
reads of DBGFH and DBGFL return delayed information about executed instructions so the host debugger
can develop a profile of executed instruction addresses.
15.3.3
Change-of-Flow Information
To minimize the amount of information stored in the FIFO, only information related to instructions that
cause a change to the normal sequential execution of instructions is stored. With knowledge of the source
and object code program stored in the target system, an external debugger system can reconstruct the path
of execution through many instructions from the change-of-flow information stored in the FIFO.
For conditional branch instructions where the branch is taken (branch condition was true), the source
address is stored (the address of the conditional branch opcode). Because BRA and BRN instructions are
not conditional, these events do not cause change-of-flow information to be stored in the FIFO.
Indirect JMP and JSR instructions use the current contents of the H:X index register pair to determine the
destination address, so the debug system stores the run-time destination address for any indirect JMP or
JSR. For interrupts, RTI, or RTS, the destination address is stored in the FIFO as change-of-flow
information.
15.3.4
Tag vs. Force Breakpoints and Triggers
Tagging is a term that refers to identifying an instruction opcode as it is fetched into the instruction queue,
but not taking any other action until and unless that instruction is actually executed by the CPU. This
distinction is important because any change-of-flow from a jump, branch, subroutine call, or interrupt
causes some instructions that have been fetched into the instruction queue to be thrown away without being
executed.
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A force-type breakpoint waits for the current instruction to finish and then acts upon the breakpoint
request. The usual action in response to a breakpoint is to go to active background mode rather than
continuing to the next instruction in the user application program.
The tag vs. force terminology is used in two contexts within the debug module. The first context refers to
breakpoint requests from the debug module to the CPU. The second refers to match signals from the
comparators to the debugger control logic. When a tag-type break request is sent to the CPU, a signal is
entered into the instruction queue along with the opcode so that if/when this opcode ever executes, the CPU
will effectively replace the tagged opcode with a BGND opcode so the CPU goes to active background
mode rather than executing the tagged instruction. When the TRGSEL control bit in the DBGT register is
set to select tag-type operation, the output from comparator A or B is qualified by a block of logic in the
debug module that tracks opcodes and only produces a trigger to the debugger if the opcode at the compare
address is actually executed. There is separate opcode tracking logic for each comparator so more than one
compare event can be tracked through the instruction queue at a time.
15.3.5
Trigger Modes
The trigger mode controls the overall behavior of a debug run. The 4-bit TRG field in the DBGT register
selects one of nine trigger modes. When TRGSEL = 1 in the DBGT register, the output of the comparator
must propagate through an opcode tracking circuit before triggering FIFO actions. The BEGIN bit in
DBGT chooses whether the FIFO begins storing data when the qualified trigger is detected (begin trace),
or the FIFO stores data in a circular fashion from the time it is armed until the qualified trigger is detected
(end trigger).
A debug run is started by writing a 1 to the ARM bit in the DBGC register, which sets the ARMF flag and
clears the AF and BF flags and the CNT bits in DBGS. A begin-trace debug run ends when the FIFO gets
full. An end-trace run ends when the selected trigger event occurs. Any debug run can be stopped manually
by writing a 0 to ARM or DBGEN in DBGC.
In all trigger modes except event-only modes, the FIFO stores change-of-flow addresses. In event-only
trigger modes, the FIFO stores data in the low-order eight bits of the FIFO.
The BEGIN control bit is ignored in event-only trigger modes and all such debug runs are begin type
traces. When TRGSEL = 1 to select opcode fetch triggers, it is not necessary to use R/W in comparisons
because opcode tags would only apply to opcode fetches that are always read cycles. It would also be
unusual to specify TRGSEL = 1 while using a full mode trigger because the opcode value is normally
known at a particular address.
The following trigger mode descriptions only state the primary comparator conditions that lead to a trigger.
Either comparator can usually be further qualified with R/W by setting RWAEN (RWBEN) and the
corresponding RWA (RWB) value to be matched against R/W. The signal from the comparator with
optional R/W qualification is used to request a CPU breakpoint if BRKEN = 1 and TAG determines
whether the CPU request will be a tag request or a force request.
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A-Only — Trigger when the address matches the value in comparator A
A OR B — Trigger when the address matches either the value in comparator A or the value in
comparator B
A Then B — Trigger when the address matches the value in comparator B but only after the address for
another cycle matched the value in comparator A. There can be any number of cycles after the A match
and before the B match.
A AND B Data (Full Mode) — This is called a full mode because address, data, and R/W (optionally)
must match within the same bus cycle to cause a trigger event. Comparator A checks address, the low byte
of comparator B checks data, and R/W is checked against RWA if RWAEN = 1. The high-order half of
comparator B is not used.
In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you
do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the
CPU breakpoint is issued when the comparator A address matches.
A AND NOT B Data (Full Mode) — Address must match comparator A, data must not match the low
half of comparator B, and R/W must match RWA if RWAEN = 1. All three conditions must be met within
the same bus cycle to cause a trigger.
In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you
do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the
CPU breakpoint is issued when the comparator A address matches.
Event-Only B (Store Data) — Trigger events occur each time the address matches the value in
comparator B. Trigger events cause the data to be captured into the FIFO. The debug run ends when the
FIFO becomes full.
A Then Event-Only B (Store Data) — After the address has matched the value in comparator A, a trigger
event occurs each time the address matches the value in comparator B. Trigger events cause the data to be
captured into the FIFO. The debug run ends when the FIFO becomes full.
Inside Range (A ≤ Address ≤ B) — A trigger occurs when the address is greater than or equal to the value
in comparator A and less than or equal to the value in comparator B at the same time.
Outside Range (Address < A or Address > B) — A trigger occurs when the address is either less than
the value in comparator A or greater than the value in comparator B.
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15.3.6
Hardware Breakpoints
The BRKEN control bit in the DBGC register may be set to 1 to allow any of the trigger conditions
described in Section 15.3.5, “Trigger Modes,” to be used to generate a hardware breakpoint request to the
CPU. TAG in DBGC controls whether the breakpoint request will be treated as a tag-type breakpoint or a
force-type breakpoint. A tag breakpoint causes the current opcode to be marked as it enters the instruction
queue. If a tagged opcode reaches the end of the pipe, the CPU executes a BGND instruction to go to active
background mode rather than executing the tagged opcode. A force-type breakpoint causes the CPU to
finish the current instruction and then go to active background mode.
If the background mode has not been enabled (ENBDM = 1) by a serial WRITE_CONTROL command
through the BKGD pin, the CPU will execute an SWI instruction instead of going to active background
mode.
15.4
Register Definition
This section contains the descriptions of the BDC and DBG registers and control bits.
Refer to the high-page register summary in the device overview chapter of this data sheet for the absolute
address assignments for all DBG registers. This section refers to registers and control bits only by their
names. A Freescale-provided equate or header file is used to translate these names into the appropriate
absolute addresses.
15.4.1
BDC Registers and Control Bits
The BDC has two registers:
• The BDC status and control register (BDCSCR) is an 8-bit register containing control and status
bits for the background debug controller.
• The BDC breakpoint match register (BDCBKPT) holds a 16-bit breakpoint match address.
These registers are accessed with dedicated serial BDC commands and are not located in the memory
space of the target MCU (so they do not have addresses and cannot be accessed by user programs).
Some of the bits in the BDCSCR have write limitations; otherwise, these registers may be read or written
at any time. For example, the ENBDM control bit may not be written while the MCU is in active
background mode. (This prevents the ambiguous condition of the control bit forbidding active background
mode while the MCU is already in active background mode.) Also, the four status bits (BDMACT, WS,
WSF, and DVF) are read-only status indicators and can never be written by the WRITE_CONTROL serial
BDC command. The clock switch (CLKSW) control bit may be read or written at any time.
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15.4.1.1
BDC Status and Control Register (BDCSCR)
This register can be read or written by serial BDC commands (READ_STATUS and WRITE_CONTROL)
but is not accessible to user programs because it is not located in the normal memory map of the MCU.
7
R
6
5
4
3
BKPTEN
FTS
CLKSW
BDMACT
ENBDM
2
1
0
WS
WSF
DVF
W
Normal
Reset
0
0
0
0
0
0
0
0
Reset in
Active BDM:
1
1
0
0
1
0
0
0
= Unimplemented or Reserved
Figure 15-5. BDC Status and Control Register (BDCSCR)
Table 15-2. BDCSCR Register Field Descriptions
Field
Description
7
ENBDM
Enable BDM (Permit Active Background Mode) — Typically, this bit is written to 1 by the debug host shortly
after the beginning of a debug session or whenever the debug host resets the target and remains 1 until a normal
reset clears it.
0 BDM cannot be made active (non-intrusive commands still allowed)
1 BDM can be made active to allow active background mode commands
6
BDMACT
Background Mode Active Status — This is a read-only status bit.
0 BDM not active (user application program running)
1 BDM active and waiting for serial commands
5
BKPTEN
BDC Breakpoint Enable — If this bit is clear, the BDC breakpoint is disabled and the FTS (force tag select)
control bit and BDCBKPT match register are ignored.
0 BDC breakpoint disabled
1 BDC breakpoint enabled
4
FTS
3
CLKSW
Force/Tag Select — When FTS = 1, a breakpoint is requested whenever the CPU address bus matches the
BDCBKPT match register. When FTS = 0, a match between the CPU address bus and the BDCBKPT register
causes the fetched opcode to be tagged. If this tagged opcode ever reaches the end of the instruction queue,
the CPU enters active background mode rather than executing the tagged opcode.
0 Tag opcode at breakpoint address and enter active background mode if CPU attempts to execute that
instruction
1 Breakpoint match forces active background mode at next instruction boundary (address need not be an
opcode)
Select Source for BDC Communications Clock — CLKSW defaults to 0, which selects the alternate BDC
clock source.
0 Alternate BDC clock source
1 MCU bus clock
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Table 15-2. BDCSCR Register Field Descriptions (continued)
Field
Description
2
WS
Wait or Stop Status — When the target CPU is in wait or stop mode, most BDC commands cannot function.
However, the BACKGROUND command can be used to force the target CPU out of wait or stop and into active
background mode where all BDC commands work. Whenever the host forces the target MCU into active
background mode, the host should issue a READ_STATUS command to check that BDMACT = 1 before
attempting other BDC commands.
0 Target CPU is running user application code or in active background mode (was not in wait or stop mode when
background became active)
1 Target CPU is in wait or stop mode, or a BACKGROUND command was used to change from wait or stop to
active background mode
1
WSF
Wait or Stop Failure Status — This status bit is set if a memory access command failed due to the target CPU
executing a wait or stop instruction at or about the same time. The usual recovery strategy is to issue a
BACKGROUND command to get out of wait or stop mode into active background mode, repeat the command
that failed, then return to the user program. (Typically, the host would restore CPU registers and stack values and
re-execute the wait or stop instruction.)
0 Memory access did not conflict with a wait or stop instruction
1 Memory access command failed because the CPU entered wait or stop mode
0
DVF
Data Valid Failure Status — This status bit is not used in the MC9S08AC16 Series because it does not have
any slow access memory.
0 Memory access did not conflict with a slow memory access
1 Memory access command failed because CPU was not finished with a slow memory access
15.4.1.2
BDC Breakpoint Match Register (BDCBKPT)
This 16-bit register holds the address for the hardware breakpoint in the BDC. The BKPTEN and FTS
control bits in BDCSCR are used to enable and configure the breakpoint logic. Dedicated serial BDC
commands (READ_BKPT and WRITE_BKPT) are used to read and write the BDCBKPT register but is
not accessible to user programs because it is not located in the normal memory map of the MCU.
Breakpoints are normally set while the target MCU is in active background mode before running the user
application program. For additional information about setup and use of the hardware breakpoint logic in
the BDC, refer to Section 15.2.4, “BDC Hardware Breakpoint.”
15.4.2
System Background Debug Force Reset Register (SBDFR)
This register contains a single write-only control bit. A serial background mode command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
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R
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
BDFR1
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
1
BDFR is writable only through serial background mode debug commands, not from user programs.
Figure 15-6. System Background Debug Force Reset Register (SBDFR)
Table 15-3. SBDFR Register Field Description
Field
Description
0
BDFR
Background Debug Force Reset — A serial active background mode command such as WRITE_BYTE allows
an external debug host to force a target system reset. Writing 1 to this bit forces an MCU reset. This bit cannot
be written from a user program.
15.4.3
DBG Registers and Control Bits
The debug module includes nine bytes of register space for three 16-bit registers and three 8-bit control
and status registers. These registers are located in the high register space of the normal memory map so
they are accessible to normal application programs. These registers are rarely if ever accessed by normal
user application programs with the possible exception of a ROM patching mechanism that uses the
breakpoint logic.
15.4.3.1
Debug Comparator A High Register (DBGCAH)
This register contains compare value bits for the high-order eight bits of comparator A. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
15.4.3.2
Debug Comparator A Low Register (DBGCAL)
This register contains compare value bits for the low-order eight bits of comparator A. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
15.4.3.3
Debug Comparator B High Register (DBGCBH)
This register contains compare value bits for the high-order eight bits of comparator B. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
15.4.3.4
Debug Comparator B Low Register (DBGCBL)
This register contains compare value bits for the low-order eight bits of comparator B. This register is
forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1.
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15.4.3.5
Debug FIFO High Register (DBGFH)
This register provides read-only access to the high-order eight bits of the FIFO. Writes to this register have
no meaning or effect. In the event-only trigger modes, the FIFO only stores data into the low-order byte of
each FIFO word, so this register is not used and will read 0x00.
Reading DBGFH does not cause the FIFO to shift to the next word. When reading 16-bit words out of the
FIFO, read DBGFH before reading DBGFL because reading DBGFL causes the FIFO to advance to the
next word of information.
15.4.3.6
Debug FIFO Low Register (DBGFL)
This register provides read-only access to the low-order eight bits of the FIFO. Writes to this register have
no meaning or effect.
Reading DBGFL causes the FIFO to shift to the next available word of information. When the debug
module is operating in event-only modes, only 8-bit data is stored into the FIFO (high-order half of each
FIFO word is unused). When reading 8-bit words out of the FIFO, simply read DBGFL repeatedly to get
successive bytes of data from the FIFO. It isn’t necessary to read DBGFH in this case.
Do not attempt to read data from the FIFO while it is still armed (after arming but before the FIFO is filled
or ARMF is cleared) because the FIFO is prevented from advancing during reads of DBGFL. This can
interfere with normal sequencing of reads from the FIFO.
Reading DBGFL while the debugger is not armed causes the address of the most-recently fetched opcode
to be stored to the last location in the FIFO. By reading DBGFH then DBGFL periodically, external host
software can develop a profile of program execution. After eight reads from the FIFO, the ninth read will
return the information that was stored as a result of the first read. To use the profiling feature, read the FIFO
eight times without using the data to prime the sequence and then begin using the data to get a delayed
picture of what addresses were being executed. The information stored into the FIFO on reads of DBGFL
(while the FIFO is not armed) is the address of the most-recently fetched opcode.
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15.4.3.7
Debug Control Register (DBGC)
This register can be read or written at any time.
7
6
5
4
3
2
1
0
DBGEN
ARM
TAG
BRKEN
RWA
RWAEN
RWB
RWBEN
0
0
0
0
0
0
0
0
R
W
Reset
Figure 15-7. Debug Control Register (DBGC)
Table 15-4. DBGC Register Field Descriptions
Field
Description
7
DBGEN
Debug Module Enable — Used to enable the debug module. DBGEN cannot be set to 1 if the MCU is secure.
0 DBG disabled
1 DBG enabled
6
ARM
Arm Control — Controls whether the debugger is comparing and storing information in the FIFO. A write is used
to set this bit (and ARMF) and completion of a debug run automatically clears it. Any debug run can be manually
stopped by writing 0 to ARM or to DBGEN.
0 Debugger not armed
1 Debugger armed
5
TAG
Tag/Force Select — Controls whether break requests to the CPU will be tag or force type requests. If
BRKEN = 0, this bit has no meaning or effect.
0 CPU breaks requested as force type requests
1 CPU breaks requested as tag type requests
4
BRKEN
Break Enable — Controls whether a trigger event will generate a break request to the CPU. Trigger events can
cause information to be stored in the FIFO without generating a break request to the CPU. For an end trace, CPU
break requests are issued to the CPU when the comparator(s) and R/W meet the trigger requirements. For a
begin trace, CPU break requests are issued when the FIFO becomes full. TRGSEL does not affect the timing of
CPU break requests.
0 CPU break requests not enabled
1 Triggers cause a break request to the CPU
3
RWA
R/W Comparison Value for Comparator A — When RWAEN = 1, this bit determines whether a read or a write
access qualifies comparator A. When RWAEN = 0, RWA and the R/W signal do not affect comparator A.
0 Comparator A can only match on a write cycle
1 Comparator A can only match on a read cycle
2
RWAEN
Enable R/W for Comparator A — Controls whether the level of R/W is considered for a comparator A match.
0 R/W is not used in comparison A
1 R/W is used in comparison A
1
RWB
R/W Comparison Value for Comparator B — When RWBEN = 1, this bit determines whether a read or a write
access qualifies comparator B. When RWBEN = 0, RWB and the R/W signal do not affect comparator B.
0 Comparator B can match only on a write cycle
1 Comparator B can match only on a read cycle
0
RWBEN
Enable R/W for Comparator B — Controls whether the level of R/W is considered for a comparator B match.
0 R/W is not used in comparison B
1 R/W is used in comparison B
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15.4.3.8
Debug Trigger Register (DBGT)
This register can be read any time, but may be written only if ARM = 0, except bits 4 and 5 are hard-wired
to 0s.
7
6
TRGSEL
BEGIN
0
0
R
5
4
0
0
3
2
1
0
TRG3
TRG2
TRG1
TRG0
0
0
0
0
W
Reset
0
0
= Unimplemented or Reserved
Figure 15-8. Debug Trigger Register (DBGT)
Table 15-5. DBGT Register Field Descriptions
Field
Description
7
TRGSEL
Trigger Type — Controls whether the match outputs from comparators A and B are qualified with the opcode
tracking logic in the debug module. If TRGSEL is set, a match signal from comparator A or B must propagate
through the opcode tracking logic and a trigger event is only signalled to the FIFO logic if the opcode at the match
address is actually executed.
0 Trigger on access to compare address (force)
1 Trigger if opcode at compare address is executed (tag)
6
BEGIN
Begin/End Trigger Select — Controls whether the FIFO starts filling at a trigger or fills in a circular manner until
a trigger ends the capture of information. In event-only trigger modes, this bit is ignored and all debug runs are
assumed to be begin traces.
0 Data stored in FIFO until trigger (end trace)
1 Trigger initiates data storage (begin trace)
3:0
TRG[3:0]
Select Trigger Mode — Selects one of nine triggering modes, as described below.
0000 A-only
0001 A OR B
0010 A Then B
0011 Event-only B (store data)
0100 A then event-only B (store data)
0101 A AND B data (full mode)
0110 A AND NOT B data (full mode)
0111 Inside range: A ≤ address ≤ B
1000 Outside range: address < A or address > B
1001 – 1111 (No trigger)
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15.4.3.9
Debug Status Register (DBGS)
This is a read-only status register.
R
7
6
5
4
3
2
1
0
AF
BF
ARMF
0
CNT3
CNT2
CNT1
CNT0
0
0
0
0
0
0
0
0
W
Reset
= Unimplemented or Reserved
Figure 15-9. Debug Status Register (DBGS)
Table 15-6. DBGS Register Field Descriptions
Field
Description
7
AF
Trigger Match A Flag — AF is cleared at the start of a debug run and indicates whether a trigger match A
condition was met since arming.
0 Comparator A has not matched
1 Comparator A match
6
BF
Trigger Match B Flag — BF is cleared at the start of a debug run and indicates whether a trigger match B
condition was met since arming.
0 Comparator B has not matched
1 Comparator B match
5
ARMF
Arm Flag — While DBGEN = 1, this status bit is a read-only image of ARM in DBGC. This bit is set by writing 1
to the ARM control bit in DBGC (while DBGEN = 1) and is automatically cleared at the end of a debug run. A
debug run is completed when the FIFO is full (begin trace) or when a trigger event is detected (end trace). A
debug run can also be ended manually by writing 0 to ARM or DBGEN in DBGC.
0 Debugger not armed
1 Debugger armed
3:0
CNT[3:0]
FIFO Valid Count — These bits are cleared at the start of a debug run and indicate the number of words of valid
data in the FIFO at the end of a debug run. The value in CNT does not decrement as data is read out of the FIFO.
The external debug host is responsible for keeping track of the count as information is read out of the FIFO.
0000 Number of valid words in FIFO = No valid data
0001 Number of valid words in FIFO = 1
0010 Number of valid words in FIFO = 2
0011 Number of valid words in FIFO = 3
0100 Number of valid words in FIFO = 4
0101 Number of valid words in FIFO = 5
0110 Number of valid words in FIFO = 6
0111 Number of valid words in FIFO = 7
1000 Number of valid words in FIFO = 8
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Appendix A
Electrical Characteristics and Timing Specifications
A.1
Introduction
This section contains electrical and timing specifications.
A.2
Parameter Classification
The electrical parameters shown in this supplement are guaranteed by various methods. To give the
customer a better understanding, the following classification is used and the parameters are tagged
accordingly in the tables where appropriate:
Table A-1. Parameter Classifications
P
Those parameters are guaranteed during production testing on each individual device.
C
Those parameters are achieved by the design characterization by measuring a
statistically relevant sample size across process variations.
T
Those parameters are achieved by design characterization on a small sample size from
typical devices under typical conditions unless otherwise noted. All values shown in
the typical column are within this category.
D
Those parameters are derived mainly from simulations.
NOTE
The classification is shown in the column labeled “C” in the parameter
tables where appropriate.
A.3
Absolute Maximum Ratings
Absolute maximum ratings are stress ratings only, and functional operation at the maxima is not
guaranteed. Stress beyond the limits specified in Table A-2 may affect device reliability or cause
permanent damage to the device. For functional operating conditions, refer to the remaining tables in this
section.
This device contains circuitry protecting against damage due to high static voltage or electrical fields;
however, it is advised that normal precautions be taken to avoid application of any voltages higher than
maximum-rated voltages to this high-impedance circuit. Reliability of operation is enhanced if unused
inputs are tied to an appropriate logic voltage level (for instance, either VSS or VDD).
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Appendix A Electrical Characteristics and Timing Specifications
Table A-2. Absolute Maximum Ratings
Rating
Symbol
Value
Unit
Supply voltage
VDD
–0.3 to + 5.8
V
Input voltage
VIn
– 0.3 to VDD + 0.3
V
Instantaneous maximum current
Single pin limit (applies to all port pins)1, 2, 3
ID
± 25
mA
Maximum current into VDD
IDD
120
mA
Tstg
–55 to +150
°C
TJ
150
°C
Storage temperature
Maximum junction temperature
1
Input must be current limited to the value specified. To determine the value of the required
current-limiting resistor, calculate resistance values for positive (VDD) and negative (VSS) clamp
voltages, then use the larger of the two resistance values.
2
All functional non-supply pins are internally clamped to VSS and VDD.
3 Power supply must maintain regulation within operating V
DD range during instantaneous and
operating maximum current conditions. If positive injection current (VIn > VDD) is greater than
IDD, the injection current may flow out of VDD and could result in external power supply going
out of regulation. Ensure external VDD load will shunt current greater than maximum injection
current. This will be the greatest risk when the MCU is not consuming power. Examples are: if
no system clock is present, or if the clock rate is very low which would reduce overall power
consumption.
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Appendix A Electrical Characteristics and Timing Specifications
A.4
Thermal Characteristics
This section provides information about operating temperature range, power dissipation, and package
thermal resistance. Power dissipation on I/O pins is usually small compared to the power dissipation in
on-chip logic and it is user-determined rather than being controlled by the MCU design. In order to take
PI/O into account in power calculations, determine the difference between actual pin voltage and VSS or
VDD and multiply by the pin current for each I/O pin. Except in cases of unusually high pin current (heavy
loads), the difference between pin voltage and VSS or VDD will be very small.
Table A-3. Thermal Characteristics
Rating
Operating temperature range (packaged)
Symbol
Value
Unit
TA
TL to TH
–40 to 125
°C
Thermal resistance 1,2,3,4
48-pin QFN
1s
2s2p
44-pin LQFP
θJA
1s
2s2p
32-pin LQFP
1s
2s2p
84
27
°C/W
73
56
85
56
1
Junction temperature is a function of die size, on-chip power dissipation, package thermal
resistance, mounting site (board) temperature, ambient temperature, air flow, power dissipation
of other components on the board, and board thermal resistance.
2 Junction to Ambient Natural Convection
3 1s - Single Layer Board, one signal layer
4 2s2p - Four Layer Board, 2 signal and 2 power layers
The average chip-junction temperature (TJ) in °C can be obtained from:
TJ = TA + (PD × θJA)
Eqn. A-1
where:
TA = Ambient temperature, °C
θJA = Package thermal resistance, junction-to-ambient, °C/W
PD = Pint + PI/O
Pint = IDD × VDD, Watts — chip internal power
PI/O = Power dissipation on input and output pins — user determined
For most applications, PI/O << Pint and can be neglected. An approximate relationship between PD and TJ
(if PI/O is neglected) is:
PD = K ÷ (TJ + 273°C)
Eqn. A-2
Solving equations 1 and 2 for K gives:
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K = PD × (TA + 273°C) + θJA × (PD)2
Eqn. A-3
where K is a constant pertaining to the particular part. K can be determined from equation 3 by measuring
PD (at equilibrium) for a known TA. Using this value of K, the values of PD and TJ can be obtained by
solving equations 1 and 2 iteratively for any value of TA.
A.5
ESD Protection and Latch-Up Immunity
Although damage from electrostatic discharge (ESD) is much less common on these devices than on early
CMOS circuits, normal handling precautions should be used to avoid exposure to static discharge.
Qualification tests are performed to ensure that these devices can withstand exposure to reasonable levels
of static without suffering any permanent damage.
All ESD testing is in conformity with AEC-Q100 Stress Test Qualification for Automotive Grade
Integrated Circuits. During the device qualification ESD stresses were performed for the Human Body
Model (HBM), the Machine Model (MM) and the Charge Device Model (CDM).
A device is defined as a failure if after exposure to ESD pulses the device no longer meets the device
specification. Complete DC parametric and functional testing is performed per the applicable device
specification at room temperature followed by hot temperature, unless specified otherwise in the device
specification.
Table A-4. ESD and Latch-up Test Conditions
Model
Human Body
Machine
Description
Symbol
Value
Unit
Series Resistance
R1
1500
Ω
Storage Capacitance
C
100
pF
Number of Pulse per pin
–
3
Series Resistance
R1
0
Ω
Storage Capacitance
C
200
pF
Number of Pulse per pin
–
3
Minimum input voltage limit
– 2.5
V
Maximum input voltage limit
7.5
V
Latch-up
Table A-5. ESD and Latch-Up Protection Characteristics
Num C
Rating
Symbol
Min
Max
Unit
1
C Human Body Model (HBM)
VHBM
± 2000
–
V
2
C Machine Model (MM)
VMM
± 200
–
V
3
C Charge Device Model (CDM)
VCDM
± 500
–
V
4
C Latch-up Current at TA = 125°C
ILAT
± 100
–
mA
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Appendix A Electrical Characteristics and Timing Specifications
A.6
DC Characteristics
This section includes information about power supply requirements, I/O pin characteristics, and power
supply current in various operating modes.
Table A-6. DC Characteristics
Num C
Parameter
Symbol
Output high voltage — Low Drive (PTxDSn = 0)
5 V, ILoad = –2 mA
3 V, ILoad = –0.6 mA
5 V, ILoad = –0.4 mA
3 V, ILoad = –0.24 mA
1
3
4
5
P Output low voltage — High Drive (PTxDSn = 1)
5 V, ILoad = 10 mA
3 V, ILoad = 3 mA
5 V, ILoad = 2 mA
3 V, ILoad = 0.4 mA
Max
VDD – 1.5
VDD – 1.5
VDD – 0.8
VDD – 0.8
—
—
—
—
—
—
—
—
Unit
V
VDD – 1.5
VDD – 1.5
VDD – 0.8
VDD – 0.8
—
—
—
—
—
—
—
—
1.5
1.5
0.8
0.8
—
—
—
—
—
—
—
—
V
VOL
1.5
1.5
0.8
0.8
—
—
—
—
—
—
—
—
IOHT
—
—
—
—
100
60
mA
5V
3V
IOLT
—
—
—
—
100
60
mA
2.7v ≤ VDD 4.5v
VIH
0.70xVDD
—
—
4.5v ≤ VDD ≤ 5.5v
VIH
0.65xVDD
—
—
VIL
—
—
0.35 x VDD
Vhys
0.06 x VDD
|IIn|
—
0.1
P Output high current — Max total IOH for all ports
5V
3V
P Output low current — Max total IOL for all ports
P Input high
voltage; all
digital inputs
6
P Input low voltage; all digital inputs
7
P Input hysteresis; all digital inputs
8
Typ1
VOH
P Output high voltage — High Drive (PTxDSn = 1)
5 V, ILoad = –10 mA
3 V, ILoad = –3 mA
5 V, ILoad = –2 mA
3 V, ILoad = –0.4 mA
Output low voltage — Low Drive (PTxDSn = 0)
5 V, ILoad = 2 mA
3 V, ILoad = 0.6 mA
5 V, ILoad = 0.4 mA
3 V, ILoad = 0.24 mA
2
Min
P Input leakage current; input only pins
2
2
V
V
1
μA
9
P High Impedance (off-state) leakage current
|IOZ|
—
0.1
1
μA
10
P Internal pullup resistors3
RPU
20
45
65
kΩ
11
P Internal pulldown resistors4
RPD
20
45
65
kΩ
12
C Input Capacitance; all non-supply pins
CIn
—
—
8
pF
13
P POR rearm voltage
VPOR
0.9
1.4
2.0
V
14
D POR rearm time
tPOR
10
—
—
μs
15
P Low-voltage detection threshold — high range
VDD falling
VDD rising
VLVDH
4.2
4.3
4.3
4.4
4.4
4.5
V
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Appendix A Electrical Characteristics and Timing Specifications
Table A-6. DC Characteristics (continued)
Num C
Parameter
Symbol
Min
Typ1
Max
Unit
VLVDL
2.48
2.54
2.56
2.62
2.64
2.7
V
16
P
Low-voltage detection threshold — low range
VDD falling
VDD rising
17
P
Low-voltage warning threshold — high range
VDD falling VLVWH
VDD rising
4.2
4.3
4.3
4.4
4.4
4.5
V
18
P
Low-voltage warning threshold — low range
VDD falling VLVWL
VDD rising
2.48
2.54
2.56
2.62
2.64
2.7
V
19
P
—
—
100
35
—
—
mV
Low-voltage inhibit reset/recover hysteresis
5V
3V
Vhys
1
Typical values are based on characterization data at 25°C unless otherwise stated.
Measured with VIn = VDD or VSS.
3 Measured with V = V .
In
SS
4 Measured with V = V .
In
DD
2
VDD–VOH (V)
Average of IOH
–6.0E-3
–5.0E-3
–40°C
25°C
125°C
IOH (A)
–4.0E-3
–3.0E-3
–2.0E-3
–1.0E-3
000E+0
0
0.3
0.5
0.8
VSupply–VOH
0.9
1.2
1.5
Figure A-1. Typical IOH (Low Drive) vs VDD–VOH at VDD = 3 V
MC9S08AC16 Series Data Sheet, Rev. 0
304
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
–20.0E-3
VDD–VOH (V)
Average of IOH
–18.0E-3
–16.0E-3
–14.0E-3
–12.0E-3
–10.0E-3
–8.0E-3
–6.0E-3
–4.0E-3
–2.0E-3
000.0E-3
IOH (A)
–40°C
25°C
125°C
0
0.3
0.5
0.8
VSupply–VOH
0.9
1.2
1.5
Figure A-2. Typical IOH (High Drive) vs VDD–VOH at VDD = 3 V
Average of IOH
–7.0E-3
–40°C
25°C
125°C
–6.0E-3
–5.0E-3
IOH (A)
–4.0E-3
–3.0E-3
–2.0E-3
–1.0E-3
000E+0
0.00
0.30
0.50
0.80
1.00
1.30
2.00
VDD–VOH (V)
VSupply–VOH
Figure A-3. Typical IOH (Low Drive) vs VDD–VOH at VDD = 5 V
VDD–VOH (V)
Average of IOH
–30.0E-3
–25.0E-3
–40°C
25°C
125°C
IOH (A)
–20.0E-3
–15.0E-3
–10.0E-3
–5.0E-3
000.0E+3
0.00
0.30
0.50
0.80
1.00
1.30
2.00
VSupply–VOH
Figure A-4. Typical IOH (High Drive) vs VDD–VOH at VDD = 5 V
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
305
Appendix A Electrical Characteristics and Timing Specifications
A.7
Supply Current Characteristics
Table A-7. Supply Current Characteristics
Num
C
Parameter
Symbol
1
C
Run supply current measured at
(CPU clock = 2 MHz, fBus = 1 MHz)
2
C
Run supply current measured at
(CPU clock = 16 MHz, fBus = 8 MHz)
3
RIDD
5
RIDD
VDD
(V)
Typ1
Max2
5
0.988
1.24
3
0.570
0.770
5
6.84
86
3
3.5
3.70
5
1.36
3
Unit
Temp
(°C)
mA
–40 to 125°C
mA
–40 to 125°C
11
23
1304
μA
0 to 70°C
–40 to 85°C
–40 to 125°C
1.05
10.5
21
110
μA
0 to 70°C
–40 to 85°C
–40 to 125°C
5
1.49
12
28
1404
μA
0 to 70°C
–40 to 85°C
–40 to 125°C
3
1.15
11
26
120
μA
0 to 70°C
–40 to 85°C
–40 to 125°C
5
300
500
500
nA
–40 to 85°C
–40 to 125°C
3
300
500
500
nA
–40 to 85°C
–40 to 125°C
5
116
150
180
μA
–40 to 85°C
–40 to 125°C
3
90
TBD
160
μA
–40 to 85°C
–40 to 125°C
5,3
5
6
TBD
μA
μA
–40 to 85°C
–40 to 125°C
Stop2 mode supply current
3
C
S2IDD
Stop3 mode supply current
4
5
6
7
1
2
3
4
5
6
7
8
C
C
C
C
S3IDD
RTI adder to stop2 or stop37
S23IDDRTI
LVD adder to stop3 (LVDE = LVDSE = 1)
Adder to stop3 for oscillator enabled8
(OSCSTEN =1)
S3IDDLVD
S3IDDOSC
Typical values are based on characterization data at 25°C unless otherwise stated. See Figure A-5 through Figure A-7 for
typical curves across voltage/temperature.
Values given here are preliminary estimates prior to completing characterization.
All modules except ADC active, ICG configured for FBE, and does not include any dc loads on port pins
Every unit tested to this parameter. All other values in the Max column are guaranteed by characterization.
All modules except ADC active, ICG configured for FBE, and does not include any dc loads on port pins
Every unit tested to this parameter. All other values in the Max column are guaranteed by characterization.
Most customers are expected to find that auto-wakeup from stop2 or stop3 can be used instead of the higher current wait
mode. Wait mode typical is 560 μA at 3 V with fBus = 1 MHz.
Values given under the following conditions: low range operation (RANGE = 0) with a 32.768kHz crystal, low power mode
(HGO = 0), clock monitor disabled (LOCD = 1).
MC9S08AC16 Series Data Sheet, Rev. 0
306
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
18
20 MHz, ADC off, FEE, 25°C
16
20 MHz, ADC off, FBE, 25°C
14
12
10
IDD
8
8 MHz, ADC off, FEE, 25°C
8 MHz, ADC off, FBE, 25°C
6
4
1 MHz, ADC off, FEE, 25°C
1 MHz, ADC off, FBE, 25°C
2
0
2.2
2.6
3.0
3.4
3.8
4.2
4.6
5.0
5.4
VDD
Note: External clock is square wave supplied by function generator. For FEE mode, external reference frequency is 4 MHz
Figure A-5. Typical Run IDD for FBE and FEE Modes, IDD vs. VDD
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
307
Appendix A Electrical Characteristics and Timing Specifications
–40°C
25°C
55°C
85°C
Stop2 IDD (A)
Average of Measurement IDD
–8.0E-3
–7.0E-3
–6.0E-3
IDD (A)
–5.0E-3
–4.0E-3
–3.0E-3
–2.0E-3
–1.0E-3
000E+0
1.8
2
2.5
3
3.5
4
4.5
5
VDD (V)
Figure A-6. Typical Stop 2 IDD
–40°C
25°C
55°C
85°C
Stop3 IDD (A)
Average of Measurement IDD
–8.0E-3
–7.0E-3
–6.0E-3
IDD (A)
–5.0E-3
–4.0E-3
–3.0E-3
–2.0E-3
–1.0E-3
000E+0
1.8
2
2.5
3
3.5
4
4.5
5
VDD (V)
Figure A-7. Typical Stop3 IDD
MC9S08AC16 Series Data Sheet, Rev. 0
308
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
A.8
ADC Characteristics
Table A-8. 5 Volt 10-bit ADC Operating Conditions
Symb
Min
Typ1
Max
Unit
Absolute
VDDAD
2.7
—
5.5
V
Delta to VDD (VDD–VDDAD)2
ΔVDDAD
–100
0
+100
mV
Delta to VSS (VSS–VSSAD)2
ΔVSSAD
–100
0
+100
mV
Ref voltage high
VREFH
2.7
VDDAD
VDDAD
V
Ref voltage low
VREFL
VSSAD
VSSAD
VSSAD
V
IDDAD
—
0.011
1
μA
Input Voltage
VADIN
VREFL
—
VREFH
V
Input capacitance
CADIN
—
4.5
5.5
pF
Input resistance
RADIN
—
3
5
kΩ
—
—
—
—
5
10
—
—
10
0.4
—
8.0
0.4
—
4.0
Characteristic
Supply voltage
Ground voltage
Supply current
Analog source resistance
External to MCU
Conditions
Stop, reset, module off
10-bit mode
fADCK > 4MHz
fADCK < 4MHz
8-bit mode (all valid fADCK)
ADC conversion clock frequency
High speed (ADLPC = 0)
kΩ
RAS
fADCK
Low power (ADLPC = 1)
MHz
1
Typical values assume VDDAD = 5.0 V, Temp = 25°C, fADCK = 1.0MHz unless otherwise stated. Typical values are for reference
only and are not tested in production.
2 dc potential difference.
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
309
Appendix A Electrical Characteristics and Timing Specifications
SIMPLIFIED
INPUT PIN EQUIVALENT
CIRCUIT
ZADIN
Pad
leakage
due to
input
protection
ZAS
RAS
SIMPLIFIED
CHANNEL SELECT
CIRCUIT
RADIN
ADC SAR
ENGINE
+
VADIN
VAS
+
–
CAS
–
RADIN
INPUT PIN
INPUT PIN
RADIN
RADIN
INPUT PIN
CADIN
Figure A-8. ADC Input Impedance Equivalency Diagram
MC9S08AC16 Series Data Sheet, Rev. 0
310
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
Table A-9. 5 Volt 10-bit ADC Characteristics (VREFH = VDDAD, VREFL = VSSAD)
C
Symb
Min
Typ1
Max
Unit
Supply current
ADLPC = 1
ADLSMP = 1
ADCO = 1
T
IDDAD
—
133
—
μA
Supply current
ADLPC = 1
ADLSMP = 0
ADCO = 1
T
IDDAD
—
218
—
μA
Supply current
ADLPC = 0
ADLSMP = 1
ADCO = 1
T
IDDAD
—
327
—
μA
Supply current
ADLPC = 0
ADLSMP = 0
ADCO = 1
T
IDDAD
—
582
—
μA
—
—
1
mA
2
3.3
5
MHz
1.25
2
3.3
—
20
—
—
40
—
—
3.5
—
—
23.5
—
—
±1
±2.5
—
±0.5
±1.0
—
±0.5
±1.0
—
±0.3
±0.5
Characteristic
ADC asynchronous clock source
tADACK = 1/fADACK
Conditions
VDDAD < 5.5 V
P
High speed (ADLPC = 0)
P
fADACK
Low power (ADLPC = 1)
Conversion time
(Including sample time)
Short sample (ADLSMP = 0)
Sample time
Short sample (ADLSMP = 0)
P
tADC
Long sample (ADLSMP = 1)
P
tADS
Long sample (ADLSMP = 1)
Total unadjusted error
Includes quantization
Differential non-linearity
10-bit mode
P
ETUE
8-bit mode
10-bit mode
P
DNL
8-bit mode
ADCK
cycles
ADCK
cycles
LSB2
LSB2
Monotonicity and no-missing-codes guaranteed
Integral non-linearity
10-bit mode
C
INL
8-bit mode
Zero-scale error
VADIN = VSSA
10-bit mode
Full-scale error
VADIN = VDDA
10-bit mode
Quantization error
10-bit mode
P
EZS
8-bit mode
P
EFS
8-bit mode
D
EQ
8-bit mode
—
±0.5
±1.0
—
±0.3
±0.5
—
±0.5
±1.5
—
±0.5
±0.5
—
±0.5
±1.5
—
±0.5
±0.5
—
—
±0.5
—
—
±0.5
LSB2
LSB2
LSB2
LSB2
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
311
Appendix A Electrical Characteristics and Timing Specifications
Table A-9. 5 Volt 10-bit ADC Characteristics (VREFH = VDDAD, VREFL = VSSAD)
Characteristic
Conditions
Input leakage error
Pad leakage3 * RAS
10-bit mode
Temp Sensor
Slope
−40°C– 25°C
Temp Sensor
Voltage
25°C
C
Symb
Min
Typ1
Max
Unit
D
EIL
—
±0.2
±2.5
LSB2
—
±0.1
±1
—
3.266
—
—
3.636
—
—
1.41
—
8-bit mode
D
m
25°C– 125°C
D
VTEMP25
mV/°C
mV
1
Typical values assume VDDAD = 5.0V, Temp = 25C, fADCK=1.0 MHz unless otherwise stated. Typical values are for reference
only and are not tested in production.
2
1 LSB = (VREFH – VREFL)/2N
3 Based on input pad leakage current. Refer to pad electricals.
A.9
Internal Clock Generation Module Characteristics
ICG
EXTAL
XTAL
RF
C1
RS
Crystal or Resonator
C2
MC9S08AC16 Series Data Sheet, Rev. 0
312
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
Table A-10. ICG DC Electrical Specifications (Temperature Range = –40 to 125°C Ambient)
Characteristic
Symbol
Load capacitors
Feedback resistor
Low range (32k to 100 kHz)
High range (1M – 16 MHz)
Series resistor
Low range
Low Gain (HGO = 0)
High Gain (HGO = 1)
High range
Low Gain (HGO = 0)
High Gain (HGO = 1)
≥ 8 MHz
4 MHz
1 MHz
1
2
Typ1
Min
Max
C1
C2
See Note 2
RF
10
1
RS
Unit
MΩ
MΩ
—
—
0
100
—
—
—
0
—
—
—
—
0
10
20
—
—
—
kΩ
Typical values are based on characterization data at VDD = 5.0V, 25°C or is typical recommended value.
See crystal or resonator manufacturer’s recommendation.
A.9.1
ICG Frequency Specifications
Table A-11. ICG Frequency Specifications
(VDDA = VDDA (min) to VDDA (max), Temperature Range = –40 to 125°C Ambient)
Num
1
2
C
Characteristic
Oscillator crystal or resonator (REFS = 1)
(Fundamental mode crystal or ceramic resonator)
Low range
High range
High Gain, FBE (HGO = 1,CLKS = 10)
High Gain, FEE (HGO = 1,CLKS = 11)
Low Power, FBE (HGO = 0, CLKS = 10)
Low Power, FEE (HGO = 0, CLKS = 11)
Input clock frequency (CLKS = 11, REFS = 0)
Low range
High range
Symbol
Min
Typ1
Max
Unit
flo
32
—
100
kHz
fhi_byp
fhi_eng
flp_byp
flp_eng
1
2
1
2
—
—
16
10
8
8
MHz
MHz
MHz
MHz
flo
fhi_eng
32
2
—
—
100
10
kHz
MHz
fExtal
0
—
40
MHz
fICGIRCLK
182.25
243
303.75
kHz
tdc
40
—
60
%
fICGOUT
fExtal (min)
flo (min)
—
—
fExtal (max)
fICGDCLKmax(
max)
MHz
8
—
3
Input clock frequency (CLKS = 10, REFS = 0)
4
Internal reference frequency (untrimmed)
5
Duty cycle of input clock (REFS = 0)
6
Output clock ICGOUT frequency
CLKS = 10, REFS = 0
All other cases
7
Minimum DCO clock (ICGDCLK) frequency
fICGDCLKmin
8
Maximum DCO clock (ICGDCLK) frequency
fICGDCLKmax
—
MHz
40
MHz
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
313
Appendix A Electrical Characteristics and Timing Specifications
Table A-11. ICG Frequency Specifications (continued)
(VDDA = VDDA (min) to VDDA (max), Temperature Range = –40 to 125°C Ambient)
Num
9
C
Characteristic
Self-clock mode (ICGOUT) frequency
Symbol
Min
fSelf
fICGDCLKmin
2
Typ1
Max
Unit
fICGDCLKmax
MHz
10.5
MHz
10
Self-clock mode reset (ICGOUT) frequency
fSelf_reset
5.5
11
Loss of reference frequency 3
Low range
High range
fLOR
5
50
25
500
kHz
12
Loss of DCO frequency 4
fLOD
0.5
1.5
MHz
—
—
ms
13
Crystal start-up time
Low range
High range
5, 6
8
t
CSTL
t
CSTH
—
—
430
4
14
FLL lock time , 7
Low range
High range
tLockl
tLockh
—
—
2
2
ms
15
FLL frequency unlock range
nUnlock
–4*N
4*N
counts
16
FLL frequency lock range
nLock
–2*N
2*N
counts
CJitter
—
0.2
% fICG
ACCint
—
—
± 0.5
±0.5
±2
±2
%
ACCint
—
—
± 0.5
±0.5
±1.5
±1.5
%
17
18
, 8 measured
at fICGOUT Max
ICGOUT period jitter,
Long term jitter (averaged over 2 ms interval)
MC9S08ACxx: Internal oscillator deviation from
trimmed frequency9
VDD = 2.7 – 5.5 V, (constant temperature)
VDD = 5.0 V ±10%, –40° C to 125°C
S9S08AWxxA: Internal oscillator deviation from
trimmed frequency10
VDD = 2.7 – 5.5 V, (constant temperature)
VDD = 5.0 V ±10%, –40° C to 125°C
1
Typical values are based on characterization data at VDD = 5.0V, 25°C unless otherwise stated.
Self-clocked mode frequency is the frequency that the DCO generates when the FLL is open-loop.
3 Loss of reference frequency is the reference frequency detected internally, which transitions the ICG into self-clocked mode if it
is not in the desired range.
4 Loss of DCO frequency is the DCO frequency detected internally, which transitions the ICG into FLL bypassed external mode
(if an external reference exists) if it is not in the desired range.
5 This parameter is characterized before qualification rather than 100% tested.
6 Proper PC board layout procedures must be followed to achieve specifications.
7 This specification applies to the period of time required for the FLL to lock after entering FLL engaged internal or external modes.
If a crystal/resonator is being used as the reference, this specification assumes it is already running.
8 Jitter is the average deviation from the programmed frequency measured over the specified interval at maximum f
ICGOUT.
Measurements are made with the device powered by filtered supplies and clocked by a stable external clock signal. Noise
injected into the FLL circuitry via VDDA and VSSA and variation in crystal oscillator frequency increase the CJitter percentage for
a given interval.
9 See Figure A-9.
10 See Figure A-9.
2
MC9S08AC16 Series Data Sheet, Rev. 0
314
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
Internal Oscillator Deviation from Trimmed Frequency
Variable
5V
3V
0.0
Percent (%)
–0.5
–1.0
–1.5
–2.0
–50
–25
0
25
50
Temp
75
100
125
Device trimmed at 25°C at 3.0 V.
Figure A-9. Internal Oscillator Deviation from Trimmed Frequency
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
315
Appendix A Electrical Characteristics and Timing Specifications
A.10
AC Characteristics
This section describes ac timing characteristics for each peripheral system. For detailed information about
how clocks for the bus are generated, see Chapter 8, “Internal Clock Generator (S08ICGV4).”
A.10.1
Control Timing
Table A-12. Control Timing
Num
C
Parameter
Symbol
Min
Typ1
Max
Unit
—
20
MHz
1
Bus frequency (tcyc = 1/fBus)
fBus
dc
2
Real-time interrupt internal oscillator period
tRTI
700
1300
μs
3
External reset pulse width2
(tcyc = 1/fSelf_reset)
textrst
1.5 x
tSelf_reset
—
ns
4
Reset low drive3
trstdrv
34 x tcyc
—
ns
5
Active background debug mode latch setup time
tMSSU
25
—
ns
6
Active background debug mode latch hold time
tMSH
25
—
ns
7
IRQ pulse width
Asynchronous path2
Synchronous path4
tILIH, tIHIL
100
1.5 x tcyc
—
—
ns
KBIPx pulse width
Asynchronous path2
Synchronous path3
tILIH, tIHIL
100
1.5 x tcyc
—
—
ns
Port rise and fall time (load = 50 pF)5
Slew rate control disabled (PTxSE = 0)
Slew rate control enabled (PTxSE = 1)
tRise, tFall
—
—
3
30
8
9
ns
1
Typical values are based on characterization data at VDD = 5.0V, 25°C unless otherwise stated.
This is the shortest pulse that is guaranteed to be recognized as a reset pin request. Shorter pulses are not guaranteed to
override reset requests from internal sources.
3 When any reset is initiated, internal circuitry drives the reset pin low for about 34 bus cycles and then samples the level on
the reset pin about 38 bus cycles later to distinguish external reset requests from internal requests.
4 This is the minimum pulse width that is guaranteed to pass through the pin synchronization circuitry. Shorter pulses may or
may not be recognized. In stop mode, the synchronizer is bypassed so shorter pulses can be recognized in that case.
5
Timing is shown with respect to 20% VDD and 80% VDD levels. Temperature range –40°C to 125°C.
2
textrst
RESET PIN
Figure A-10. Reset Timing
MC9S08AC16 Series Data Sheet, Rev. 0
316
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
BKGD/MS
RESET
tMSH
tMSSU
Figure A-11. Active Background Debug Mode Latch Timing
tIHIL
IRQ/KBIP7-KBIP4
IRQ/KBIPx
tILIH
Figure A-12. IRQ/KBIPx Timing
A.10.2
Timer/PWM (TPM) Module Timing
Synchronizer circuits determine the shortest input pulses that can be recognized or the fastest clock that
can be used as the optional external source to the timer counter. These synchronizers operate from the
current bus rate clock.
Table A-13. TPM Input Timing
Function
Symbol
Min
Max
Unit
External clock frequency
fTPMext
dc
fBus/4
MHz
External clock period
tTPMext
4
—
tcyc
External clock high time
tclkh
1.5
—
tcyc
External clock low time
tclkl
1.5
—
tcyc
tICPW
1.5
—
tcyc
Input capture pulse width
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
317
Appendix A Electrical Characteristics and Timing Specifications
tTPMext
tclkh
TPMxCLK
tclkl
Figure A-13. Timer External Clock
tICPW
TPMxCHn
TPMxCHn
tICPW
Figure A-14. Timer Input Capture Pulse
MC9S08AC16 Series Data Sheet, Rev. 0
318
PRELIMINARY
Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
A.11
SPI Characteristics
Table A-14 and Figure A-15 through Figure A-18 describe the timing requirements for the SPI system.
Table A-14. SPI Electrical Characteristic
Num
C
Characteristic1
Symbol
Min
Max
Unit
Master
Slave
fop
fop
fBus/2048
dc
fBus/2
fBus/4
Hz
Master
Slave
tSCK
tSCK
2
4
2048
—
tcyc
tcyc
Master
Slave
tLead
tLead
—
1/2
1/2
—
tSCK
tSCK
Master
Slave
tLag
tLag
—
1/2
1/2
—
tSCK
tSCK
Clock (SPSCK) high time
Master and Slave
tSCKH
1/2 tSCK – 25
—
ns
Clock (SPSCK) low time Master
and Slave
tSCKL
1/2 tSCK – 25
—
ns
Master
Slave
tSI(M)
tSI(S)
30
30
—
—
ns
ns
Master
Slave
tHI(M)
tHI(S)
30
30
—
—
ns
ns
Operating frequency
1
2
3
4
5
6
7
Cycle time
Enable lead time
Enable lag time
Data setup time (inputs)
Data hold time (inputs)
8
Access time, slave2
tA
0
40
ns
9
Disable time, slave3
tdis
—
40
ns
10
Data setup time (outputs)
Master
Slave
tSO
tSO
25
25
—
—
ns
ns
tHO
tHO
–10
–10
—
—
ns
ns
11
Data hold time (outputs)
Master
Slave
1
All timing is shown with respect to 20% VDD and 70% VDD, unless noted; 100 pF load on all SPI
pins. All timing assumes slew rate control disabled and high drive strength enabled for SPI output
pins.
2
Time to data active from high-impedance state.
3 Hold time to high-impedance state.
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Appendix A Electrical Characteristics and Timing Specifications
SS1
(OUTPUT)
1
2
SCK
(CPOL = 0)
(OUTPUT)
3
5
4
SCK
(CPOL = 1)
(OUTPUT)
5
4
6
MISO
(INPUT)
7
MSB IN2
BIT 6 . . . 1
10
MOSI
(OUTPUT)
LSB IN
10
MSB OUT2
11
BIT 6 . . . 1
LSB OUT
NOTES:
1. SS output mode (MODFEN = 1, SSOE = 1).
2. LSBF = 0. For LSBF = 1, bit order is LSB, bit 1, ..., bit 6, MSB.
Figure A-15. SPI Master Timing (CPHA = 0)
SS(1)
(OUTPUT)
1
2
SCK
(CPOL = 0)
(OUTPUT)
3
5
4
SCK
(CPOL = 1)
(OUTPUT)
5
4
6
MISO
(INPUT)
7
MSB IN(2)
BIT 6 . . . 1
10
MOSI
(OUTPUT)
LSB IN
11
MSB OUT(2)
BIT 6 . . . 1
LSB OUT
NOTES:
1. SS output mode (MODFEN = 1, SSOE = 1).
2. LSBF = 0. For LSBF = 1, bit order is LSB, bit 1, ..., bit 6, MSB.
Figure A-16. SPI Master Timing (CPHA = 1)
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
SS
(INPUT)
3
1
SCK
(CPOL = 0)
(INPUT)
5
4
2
SCK
(CPOL = 1)
(INPUT)
5
4
8
MISO
(OUTPUT)
11
10
BIT 6 . . . 1
MSB OUT
SLAVE
SLAVE LSB OUT
SEE
NOTE
7
6
MOSI
(INPUT)
9
BIT 6 . . . 1
MSB IN
LSB IN
NOTE:
1. Not defined but normally MSB of character just received
Figure A-17. SPI Slave Timing (CPHA = 0)
SS
(INPUT)
1
3
2
SCK
(CPOL = 0)
(INPUT)
5
4
SCK
(CPOL = 1)
(INPUT)
5
4
10
MISO
(OUTPUT)
SEE
NOTE
8
MOSI
(INPUT)
SLAVE
11
MSB OUT
6
BIT 6 . . . 1
9
SLAVE LSB OUT
7
MSB IN
BIT 6 . . . 1
LSB IN
NOTE:
1. Not defined but normally LSB of character just received
Figure A-18. SPI Slave Timing (CPHA = 1)
MC9S08AC16 Series Data Sheet, Rev. 0
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PRELIMINARY
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Appendix A Electrical Characteristics and Timing Specifications
A.12
FLASH Specifications
This section provides details about program/erase times and program-erase endurance for the FLASH
memory.
Program and erase operations do not require any special power sources other than the normal VDD supply.
For more detailed information about program/erase operations, see Chapter 4, “Memory.”
Table A-15. FLASH Characteristics
Num
C
Characteristic
Symbol
Min
Typ1
Max
Unit
1
Supply voltage for program/erase
Vprog/erase
2.7
5.5
V
2
Supply voltage for read operation
VRead
2.7
5.5
V
3
Internal FCLK frequency2
fFCLK
150
200
kHz
4
Internal FCLK period (1/FCLK)
tFcyc
5
6.67
μs
5
Byte program time (random location)(2)
tprog
9
tFcyc
6
Byte program time (burst mode)(2)
tBurst
4
tFcyc
7
Page erase time3
tPage
4000
tFcyc
8
Mass erase time(2)
tMass
20,000
tFcyc
9
Program/erase endurance4
TL to TH = –40°C to + 125°C
T = 25°C
10
C
Data retention5
tD_ret
10,000
—
—
100,000
—
—
cycles
15
100
—
years
1
Typical values are based on characterization data at VDD = 5.0 V, 25°C unless otherwise stated.
The frequency of this clock is controlled by a software setting.
3
These values are hardware state machine controlled. User code does not need to count cycles. This information
supplied for calculating approximate time to program and erase.
4 Typical endurance for FLASH was evaluated for this product family on the 9S12Dx64. For additional information
on how Freescale Semiconductor defines typical endurance, please refer to Engineering Bulletin EB619, Typical
Endurance for Nonvolatile Memory.
5
Typical data retention values are based on intrinsic capability of the technology measured at high temperature and
de-rated to 25°C using the Arrhenius equation. For additional information on how Freescale Semiconductor defines
typical data retention, please refer to Engineering Bulletin EB618, Typical Data Retention for Nonvolatile Memory.
2
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Appendix A Electrical Characteristics and Timing Specifications
A.13
EMC Performance
Electromagnetic compatibility (EMC) performance is highly dependant on the environment in which the
MCU resides. Board design and layout, circuit topology choices, location and characteristics of external
components as well as MCU software operation all play a significant role in EMC performance. The
system designer should consult Freescale applications notes such as AN2321, AN1050, AN1263,
AN2764, and AN1259 for advice and guidance specifically targeted at optimizing EMC performance.
MC9S08AC16 Series Data Sheet, Rev. 0
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Appendix A Electrical Characteristics and Timing Specifications
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
Appendix B
Ordering Information and Mechanical Drawings
B.1
Ordering Information
This section contains ordering information for the MC9S08AC16 Series devices. See below for an
example of the device numbering system.
Orderable Part Numbering System
Device
1
2
Table B-1. Device Comparison
Memory
Number1
Available Packages2
Qualification
FLASH
RAM
Type
Type
MC9S08AC16
MC9S08AC8
16,384
8192
1024
768
48-pin QFN
44-pin LQFP
32-pin LQFP
Consumer and Industrial
S9S08AW16A
S9S08AW8A
16,384
8192
1024
768
48-pin QFN
44-pin LQFP
32-pin LQFP
Automotive
See Table 1-1 for a complete description of modules included on each device.
See Table B-2 and Table B-3 for package information.
The orderable part numbers for the MC9S08AC16 Series devices varies according to the device family.
Refer to Figure B-1 and Figure B-2 for examples.
MC
9
S08
AC n
C
xx
E
Pb Free Indicator
- E = Pb Free
Status
- MC = Consumer &
Industrial
Package Designator
Two letter descriptor
(refer to Table B-2).
Main Memory Type
- 9 = Flash-based
Temperature Option
- C = -40 to 85 °C
- V = -40 to 105 °C
- M = -40 to 125 °C
Core
Family
- AC
Memory Size
(Approx)
- 16 Kbytes
- 8 Kbytes
Figure B-1. Consumer & Industrial Device Numbering System
MC9S08AC16 Series Data Sheet, Rev. 0
Freescale Semiconductor
PRELIMINARY
325
Appendix B Ordering Information and Mechanical Drawings
S
9
S08
AW n
A
E2
C
xx
Status
- S = Auto Qualified
Package Designator
Two letter descriptor
(refer to Table B-3).
Main Memory Type
- 9 = Flash-based
Temperature Range
- C = -40 to 85 °C
- V = -40 to 105 °C
- M = -40 to 125 °C
Core
Mask Set Identifier
Family
- AW
Memory Size
(Approx)
- 16 Kbytes
- 8 Kbytes
- Alpha character references
wafer fab.
- E = Chandler
- Numeric character identifies
mask revision.
Device
Version
Figure B-2. Automotive Device Numbering System
B.2
Mechanical Drawings
This following pages contain mechanical specifications for MC9S08AC16 Series package options. See the
following tables for the document numbers that correspond to each package type.
Table B-2. MC9S08AC16 and MC9S08AC8 Consumer & Industrial Package Information
Pin Count
Type
Designator
Document No.
48
QFN
FD
98ARH99048A
44
LQFP
FG
98ASS23225W
32
LQFP
FJ
98ASH70029A
Table B-3. S9S08AW16A and S9S08AW8A Automotive Package Information
Pin Count
Type
Designator
Document No.
48
QFN
FT
98ARH99048A
44
LQFP
LS
98ASS23225W
32
LQFP
LM
98ASH70029A
MC9S08AC16 Series Data Sheet, Rev. 0
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Freescale Semiconductor
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