FREESCALE MC9S08GT60ACFBE

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MC9S08GB60
MC9S08GB32
MC9S08GT60
MC9S08GT32
MC9S08GT16
Data Sheet
HCS08
Microcontrollers
MC9S08GB60/D
Rev. 2.3
12/2004
freescale.com
MC9S08GB/GT Data Sheet
Covers: MC9S08GB60
MC9S08GB32
MC9S08GT60
MC9S08GT32
MC9S08GT16
MC9S08GB60
Rev. 2.3
12/2004
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.
Revision
Number
Revision
Date
1.0
4/25/2003
Description of Changes
Initial release
1.1
Electricals change, appendix A only
1.2
Electricals change, appendix A only
1.3
10/2/2003
Added module version table; clarifications
1.4
10/29/2003
Fixed typos and made corrections and clarifications
1.5
11/12/2003
Added 1-MHz IDD values to Electricals, appendix A
2
2/10/2004
Changed format of register names to enable reuse of code (from SCIBD to SCI1BD, even when
only one instance of a module on a chip)
Added new device: MC9S08GT16 to book. Added new 48-pin QFN package to book. BKGDPE
description in Section 5 — changed PTD0 to PTG0. Changed typo in CPU section that listed
MOV instruction as being 6 cycles instead of 5 (Table 8-2).
2.2
9/2/2004
Format to Freescale look-and-feel; Clarified RTI clock sources and other changes in Chapter 5;
updated ICG initialization examples; expanded descriptions of LOLS and LOCS bits in ICGS1;
updated ICG electricals Table A-9 and added a figure
12/01/2004
Minor changes to Table 7-4, Table 7-5, Table A-9;
Clarifications in Section 11.10.6, “SCI x Control Register 3 (SCIxC3)”, Section 11.7, “Interrupts
and Status Flags”, Section 11.8.1, “8- and 9-Bit Data Modes”, PTG availability in 48-pin
package (see Table 2-2)
2.3
This product incorporates SuperFlash® technology licensed from SST.
Freescale‚ and the Freescale logo are trademarks of Freescale Semiconductor, Inc.
© Freescale Semiconductor, Inc., 2004. All rights reserved.
MC9S08GB/GT Data Sheet, Rev. 2.3
4
Freescale Semiconductor
List of Chapters
Chapter 1
Introduction.............................................................................. 17
Chapter 2
Pins and Connections ............................................................. 23
Chapter 3
Modes of Operation ................................................................. 33
Chapter 4
Memory ..................................................................................... 39
Chapter 5
Resets, Interrupts, and System Configuration ..................... 61
Chapter 6
Parallel Input/Output ............................................................... 77
Chapter 7
Internal Clock Generator (ICG) Module ................................. 97
Chapter 8
Central Processor Unit (CPU)............................................... 125
Chapter 9
Keyboard Interrupt (KBI) Module ......................................... 145
Chapter 10
Timer/PWM (TPM) Module..................................................... 151
Chapter 11
Serial Communications Interface (SCI) Module.................. 167
Chapter 12
Serial Peripheral Interface (SPI) Module.............................. 187
Chapter 13
Inter-Integrated Circuit (IIC) Module .................................... 203
Chapter 14
Analog-to-Digital Converter (ATD) Module ......................... 219
Chapter 15
Development Support ........................................................... 235
Appendix A
Electrical Characteristics...................................................... 259
Appendix B
Ordering Information and Mechanical Drawings................ 281
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
5
Contents
Section Number
Title
Page
Chapter 1
Introduction
1.1
1.2
1.3
1.4
Overview .........................................................................................................................................17
Features ...........................................................................................................................................17
1.2.1 Standard Features of the HCS08 Family .........................................................................17
1.2.2 Features of MC9S08GB/GT Series of MCUs .................................................................17
1.2.3 Devices in the MC9S08GB/GT Series ............................................................................18
MCU Block Diagrams .....................................................................................................................19
System Clock Distribution ..............................................................................................................21
Chapter 2
Pins and Connections
2.1
2.2
2.3
Introduction .....................................................................................................................................23
Device Pin Assignment ...................................................................................................................23
Recommended System Connections ...............................................................................................26
2.3.1 Power ...............................................................................................................................28
2.3.2 Oscillator ..........................................................................................................................28
2.3.3 Reset ................................................................................................................................28
2.3.4 Background / Mode Select (PTG0/BKGD/MS) ..............................................................29
2.3.5 General-Purpose I/O and Peripheral Ports .......................................................................29
2.3.6 Signal Properties Summary .............................................................................................31
Chapter 3
Modes of Operation
3.1
3.2
3.3
3.4
3.5
3.6
Introduction .....................................................................................................................................33
Features ...........................................................................................................................................33
Run Mode ........................................................................................................................................33
Active Background Mode ................................................................................................................33
Wait Mode .......................................................................................................................................34
Stop Modes ......................................................................................................................................34
3.6.1 Stop1 Mode ......................................................................................................................35
3.6.2 Stop2 Mode ......................................................................................................................35
3.6.3 Stop3 Mode ......................................................................................................................36
3.6.4 Active BDM Enabled in Stop Mode ................................................................................36
3.6.5 LVD Enabled in Stop Mode .............................................................................................37
3.6.6 On-Chip Peripheral Modules in Stop Modes ...................................................................37
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
7
Section Number
Title
Page
Chapter 4
Memory
4.1
4.2
4.3
4.4
4.5
4.6
MC9S08GB/GT Memory Map .......................................................................................................39
4.1.1 Reset and Interrupt Vector Assignments ..........................................................................39
Register Addresses and Bit Assignments ........................................................................................41
RAM ................................................................................................................................................46
FLASH ............................................................................................................................................46
4.4.1 Features ............................................................................................................................47
4.4.2 Program and Erase Times ................................................................................................47
4.4.3 Program and Erase Command Execution ........................................................................48
4.4.4 Burst Program Execution .................................................................................................49
4.4.5 Access Errors ...................................................................................................................50
4.4.6 FLASH Block Protection .................................................................................................51
4.4.7 Vector Redirection ...........................................................................................................52
Security ............................................................................................................................................52
FLASH Registers and Control Bits .................................................................................................53
4.6.1 FLASH Clock Divider Register (FCDIV) .......................................................................54
4.6.2 FLASH Options Register (FOPT and NVOPT) ..............................................................55
4.6.3 FLASH Configuration Register (FCNFG) .......................................................................56
4.6.4 FLASH Protection Register (FPROT and NVPROT) ......................................................56
4.6.5 FLASH Status Register (FSTAT) .....................................................................................58
4.6.6 FLASH Command Register (FCMD) ..............................................................................59
Chapter 5
Resets, Interrupts, and System Configuration
5.1
5.2
5.3
5.4
5.5
5.6
5.7
Introduction .....................................................................................................................................61
Features ...........................................................................................................................................61
MCU Reset ......................................................................................................................................61
Computer Operating Properly (COP) Watchdog .............................................................................62
Interrupts .........................................................................................................................................62
5.5.1 Interrupt Stack Frame ......................................................................................................63
5.5.2 External Interrupt Request (IRQ) Pin ..............................................................................64
5.5.2.1 Pin Configuration Options ..............................................................................64
5.5.2.2 Edge and Level Sensitivity ..............................................................................65
5.5.3 Interrupt Vectors, Sources, and Local Masks ..................................................................65
Low-Voltage Detect (LVD) System ................................................................................................67
5.6.1 Power-On Reset Operation ..............................................................................................67
5.6.2 LVD Reset Operation .......................................................................................................67
5.6.3 LVD Interrupt Operation .................................................................................................67
5.6.4 Low-Voltage Warning (LVW) ..........................................................................................67
Real-Time Interrupt (RTI) ...............................................................................................................67
MC9S08GB/GT Data Sheet, Rev. 2.3
8
Freescale Semiconductor
Section Number
5.8
Title
Page
Reset, Interrupt, and System Control Registers and Control Bits ...................................................68
5.8.1 Interrupt Pin Request Status and Control Register (IRQSC) ...........................................68
5.8.2 System Reset Status Register (SRS) ................................................................................69
5.8.3 System Background Debug Force Reset Register (SBDFR) ...........................................71
5.8.4 System Options Register (SOPT) ....................................................................................71
5.8.5 System Device Identification Register (SDIDH, SDIDL) ...............................................72
5.8.6 System Real-Time Interrupt Status and Control Register (SRTISC) ...............................73
5.8.7 System Power Management Status and Control 1 Register (SPMSC1) ..........................74
5.8.8 System Power Management Status and Control 2 Register (SPMSC2) ..........................75
Chapter 6
Parallel Input/Output
6.1
6.2
6.3
6.4
6.5
6.6
Introduction .....................................................................................................................................77
Features ...........................................................................................................................................79
Pin Descriptions ..............................................................................................................................79
6.3.1 Port A and Keyboard Interrupts .......................................................................................79
6.3.2 Port B and Analog to Digital Converter Inputs ...............................................................80
6.3.3 Port C and SCI2, IIC, and High-Current Drivers ............................................................80
6.3.4 Port D, TPM1 and TPM2 .................................................................................................81
6.3.5 Port E, SCI1, and SPI ......................................................................................................81
6.3.6 Port F and High-Current Drivers .....................................................................................82
6.3.7 Port G, BKGD/MS, and Oscillator ..................................................................................82
Parallel I/O Controls ........................................................................................................................82
6.4.1 Data Direction Control ....................................................................................................83
6.4.2 Internal Pullup Control ....................................................................................................83
6.4.3 Slew Rate Control ............................................................................................................83
Stop Modes ......................................................................................................................................84
Parallel I/O Registers and Control Bits ...........................................................................................84
6.6.1 Port A Registers (PTAD, PTAPE, PTASE, and PTADD) ................................................84
6.6.2 Port B Registers (PTBD, PTBPE, PTBSE, and PTBDD) ...............................................86
6.6.3 Port C Registers (PTCD, PTCPE, PTCSE, and PTCDD) ...............................................87
6.6.4 Port D Registers (PTDD, PTDPE, PTDSE, and PTDDD) ..............................................89
6.6.5 Port E Registers (PTED, PTEPE, PTESE, and PTEDD) ................................................90
6.6.6 Port F Registers (PTFD, PTFPE, PTFSE, and PTFDD) ..................................................92
6.6.7 Port G Registers (PTGD, PTGPE, PTGSE, and PTGDD) ..............................................93
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
9
Section Number
Title
Page
Chapter 7
Internal Clock Generator (ICG) Module
7.1
7.2
7.3
7.4
7.5
Introduction .....................................................................................................................................99
7.1.1 Features ..........................................................................................................................100
7.1.2 Modes of Operation .......................................................................................................101
External Signal Description ..........................................................................................................101
7.2.1 Overview ........................................................................................................................101
7.2.2 Detailed Signal Descriptions .........................................................................................102
7.2.2.1 EXTAL— External Reference Clock / Oscillator Input ...............................102
7.2.2.2 XTAL— Oscillator Output ...........................................................................102
7.2.3 External Clock Connections ..........................................................................................102
7.2.4 External Crystal/Resonator Connections .......................................................................102
Functional Description ..................................................................................................................103
7.3.1 Off Mode (Off) ..............................................................................................................103
7.3.1.1 BDM Active .................................................................................................103
7.3.1.2 OSCSTEN Bit Set .........................................................................................103
7.3.1.3 Stop/Off Mode Recovery ..............................................................................104
7.3.2 Self-Clocked Mode (SCM) ............................................................................................104
7.3.3 FLL Engaged, Internal Clock (FEI) Mode ....................................................................105
7.3.3.1 FLL Engaged Internal Unlocked ..................................................................105
7.3.3.2 FLL Engaged Internal Locked ......................................................................106
7.3.4 FLL Bypassed, External Clock (FBE) Mode ................................................................106
7.3.5 FLL Engaged, External Clock (FEE) Mode ..................................................................106
7.3.5.1 FLL Engaged External Unlocked .................................................................106
7.3.5.2 FLL Engaged External Locked .....................................................................107
7.3.6 FLL Lock and Loss-of-Lock Detection .........................................................................107
7.3.7 FLL Loss-of-Clock Detection ........................................................................................107
7.3.8 Clock Mode Requirements ............................................................................................108
7.3.9 Fixed Frequency Clock ..................................................................................................109
Initialization/Application Information ..........................................................................................110
7.4.1 Introduction ....................................................................................................................110
7.4.2 Example #1: External Crystal = 32 kHz, Bus Frequency = 4.19 MHz .........................112
7.4.3 Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz ............................113
7.4.4 Example #3: No External Crystal Connection, 5.4 MHz Bus Frequency .....................114
7.4.5 Example #4: Internal Clock Generator Trim .................................................................116
ICG Registers and Control Bits .....................................................................................................117
7.5.1 ICG Control Register 1 (ICGC1) ......................................................................118
7.5.2 ICG Control Register 2 (ICGC2) ......................................................................119
7.5.3 ICG Status Register 1 (ICGS1) .................................................................................120
7.5.4 ICG Status Register 2 (ICGS2) ........................................................................122
7.5.5 ICG Filter Registers (ICGFLTU, ICGFLTL) .......................................................122
7.5.6 ICG Trim Register (ICGTRM) ...........................................................................123
MC9S08GB/GT Data Sheet, Rev. 2.3
10
Freescale Semiconductor
Section Number
Title
Page
Chapter 8
Central Processor Unit (CPU)
8.1
8.2
8.3
8.4
8.5
8.6
Introduction ...................................................................................................................................125
Features .........................................................................................................................................126
Programmer’s Model and CPU Registers .....................................................................................126
8.3.1 Accumulator (A) ............................................................................................................127
8.3.2 Index Register (H:X) .....................................................................................................127
8.3.3 Stack Pointer (SP) ..........................................................................................................128
8.3.4 Program Counter (PC) ...................................................................................................128
8.3.5 Condition Code Register (CCR) ....................................................................................128
Addressing Modes .........................................................................................................................130
8.4.1 Inherent Addressing Mode (INH) ..................................................................................130
8.4.2 Relative Addressing Mode (REL) .................................................................................130
8.4.3 Immediate Addressing Mode (IMM) .............................................................................130
8.4.4 Direct Addressing Mode (DIR) .....................................................................................130
8.4.5 Extended Addressing Mode (EXT) ...............................................................................131
8.4.6 Indexed Addressing Mode .............................................................................................131
8.4.6.1 Indexed, No Offset (IX) ................................................................................131
8.4.6.2 Indexed, No Offset with Post Increment (IX+) .............................................131
8.4.6.3 Indexed, 8-Bit Offset (IX1) ...........................................................................131
8.4.6.4 Indexed, 8-Bit Offset with Post Increment (IX1+) .......................................131
8.4.6.5 Indexed, 16-Bit Offset (IX2) .........................................................................131
8.4.6.6 SP-Relative, 8-Bit Offset (SP1) ....................................................................131
8.4.6.7 SP-Relative, 16-Bit Offset (SP2) ..................................................................132
Special Operations .........................................................................................................................132
8.5.1 Reset Sequence ..............................................................................................................132
8.5.2 Interrupt Sequence .........................................................................................................132
8.5.3 Wait Mode Operation .....................................................................................................133
8.5.4 Stop Mode Operation .....................................................................................................133
8.5.5 BGND Instruction ..........................................................................................................134
HCS08 Instruction Set Summary ..................................................................................................134
Chapter 9
Keyboard Interrupt (KBI) Module
9.1
9.2
9.3
9.4
9.5
Introduction ...................................................................................................................................145
9.1.1 Port A and Keyboard Interrupt Pins ..............................................................................145
Features .........................................................................................................................................145
KBI Block Diagram ......................................................................................................................147
Keyboard Interrupt (KBI) Module ................................................................................................147
9.4.1 Pin Enables ....................................................................................................................147
9.4.2 Edge and Level Sensitivity ............................................................................................147
9.4.3 KBI Interrupt Controls ...................................................................................................148
KBI Registers and Control Bits .....................................................................................................148
9.5.1 KBI Status and Control Register (KBI1SC) ..................................................................148
9.5.2 KBI Pin Enable Register (KBI1PE) ..............................................................................150
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
11
Section Number
Title
Page
Chapter 10
Timer/PWM (TPM) Module
10.1
10.2
10.3
10.4
Introduction ...................................................................................................................................151
Features .........................................................................................................................................151
TPM Block Diagram .....................................................................................................................153
Pin Descriptions ............................................................................................................................154
10.4.1 External TPM Clock Sources ........................................................................................154
10.4.2 TPMxCHn — TPMx Channel n I/O Pins ......................................................................154
10.5 Functional Description ..................................................................................................................154
10.5.1 Counter ..........................................................................................................................155
10.5.2 Channel Mode Selection ................................................................................................156
10.5.2.1 Input Capture Mode ......................................................................................156
10.5.2.2 Output Compare Mode .................................................................................156
10.5.2.3 Edge-Aligned PWM Mode ...........................................................................156
10.5.3 Center-Aligned PWM Mode ..........................................................................................157
10.6 TPM Interrupts ..............................................................................................................................159
10.6.1 Clearing Timer Interrupt Flags ......................................................................................159
10.6.2 Timer Overflow Interrupt Description ...........................................................................159
10.6.3 Channel Event Interrupt Description .............................................................................159
10.6.4 PWM End-of-Duty-Cycle Events ..................................................................................160
10.7 TPM Registers and Control Bits ...................................................................................................160
10.7.1 Timer x Status and Control Register (TPMxSC) ...........................................................160
10.7.2 Timer x Counter Registers (TPMxCNTH:TPMxCNTL) ..............................................162
10.7.3 Timer x Counter Modulo Registers (TPMxMODH:TPMxMODL) ..............................163
10.7.4 Timer x Channel n Status and Control Register (TPMxCnSC) .....................................163
10.7.5 Timer x Channel Value Registers (TPMxCnVH:TPMxCnVL) .....................................165
Chapter 11
Serial Communications Interface (SCI) Module
11.1
11.2
11.3
11.4
11.5
Introduction ...................................................................................................................................167
Features .........................................................................................................................................169
SCI System Description ................................................................................................................169
Baud Rate Generation ...................................................................................................................169
Transmitter Functional Description ...............................................................................................170
11.5.1 Transmitter Block Diagram ...........................................................................................170
11.5.2 Send Break and Queued Idle .........................................................................................172
11.6 Receiver Functional Description ...................................................................................................172
11.6.1 Receiver Block Diagram ................................................................................................172
11.6.2 Data Sampling Technique ..............................................................................................174
11.6.3 Receiver Wakeup Operation ..........................................................................................174
11.6.3.1 Idle-Line Wakeup ..........................................................................................175
11.6.3.2 Address-Mark Wakeup .................................................................................175
11.7 Interrupts and Status Flags ............................................................................................................175
MC9S08GB/GT Data Sheet, Rev. 2.3
12
Freescale Semiconductor
Section Number
Title
Page
11.8 Additional SCI Functions ..............................................................................................................176
11.8.1 8- and 9-Bit Data Modes ................................................................................................176
11.9 Stop Mode Operation ....................................................................................................................176
11.9.1 Loop Mode .....................................................................................................................177
11.9.2 Single-Wire Operation ...................................................................................................177
11.10 SCI Registers and Control Bits .....................................................................................................177
11.10.1 SCI x Baud Rate Registers (SCIxBDH, SCIxBDL) ......................................................177
11.10.2 SCI x Control Register 1 (SCIxC1) ...............................................................................178
11.10.3 SCI x Control Register 2 (SCIxC2) ...............................................................................180
11.10.4 SCI x Status Register 1 (SCIxS1) ..................................................................................181
11.10.5 SCI x Status Register 2 (SCIxS2) ..................................................................................183
11.10.6 SCI x Control Register 3 (SCIxC3) ...............................................................................184
11.10.7 SCI x Data Register (SCIxD) ........................................................................................185
Chapter 12
Serial Peripheral Interface (SPI) Module
12.1 Features .........................................................................................................................................189
12.2 Block Diagrams .............................................................................................................................189
12.2.1 SPI System Block Diagram ...........................................................................................189
12.2.2 SPI Module Block Diagram ...........................................................................................190
12.2.3 SPI Baud Rate Generation .............................................................................................192
12.3 Functional Description ..................................................................................................................192
12.3.1 SPI Clock Formats .........................................................................................................193
12.3.2 SPI Pin Controls ............................................................................................................195
12.3.2.1 SPSCK1 — SPI Serial Clock ........................................................................195
12.3.2.2 MOSI1 — Master Data Out, Slave Data In ..................................................195
12.3.2.3 MISO1 — Master Data In, Slave Data Out ..................................................195
12.3.2.4 SS1 — Slave Select .......................................................................................195
12.3.3 SPI Interrupts .................................................................................................................196
12.3.4 Mode Fault Detection ....................................................................................................196
12.4 SPI Registers and Control Bits ......................................................................................................196
12.4.1 SPI Control Register 1 (SPI1C1) ...................................................................................197
12.4.2 SPI Control Register 2 (SPI1C2) ...................................................................................198
12.4.3 SPI Baud Rate Register (SPI1BR) .................................................................................199
12.4.4 SPI Status Register (SPI1S) ...........................................................................................201
12.4.5 SPI Data Register (SPI1D) ............................................................................................202
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
13
Section Number
Title
Page
Chapter 13
Inter-Integrated Circuit (IIC) Module
13.1 Introduction ...................................................................................................................................205
13.1.1 Features ..........................................................................................................................205
13.1.2 Modes of Operation .......................................................................................................205
13.1.3 Block Diagram ...............................................................................................................206
13.1.4 Detailed Signal Descriptions .........................................................................................206
13.1.4.1 SCL1 — Serial Clock Line ...........................................................................206
13.1.4.2 SDA1 — Serial Data Line ............................................................................206
13.2 Functional Description ..................................................................................................................207
13.2.1 IIC Protocol ...................................................................................................................207
13.2.1.1 START Signal ...............................................................................................208
13.2.1.2 Slave Address Transmission .........................................................................208
13.2.1.3 Data Transfer .................................................................................................208
13.2.1.4 STOP Signal ..................................................................................................209
13.2.1.5 Repeated START Signal ...............................................................................209
13.2.1.6 Arbitration Procedure ....................................................................................209
13.2.1.7 Clock Synchronization ..................................................................................209
13.2.1.8 Handshaking .................................................................................................210
13.2.1.9 Clock Stretching ............................................................................................210
13.3 Resets ............................................................................................................................................210
13.4 Interrupts .......................................................................................................................................211
13.4.1 Byte Transfer Interrupt ..................................................................................................211
13.4.2 Address Detect Interrupt ................................................................................................211
13.4.3 Arbitration Lost Interrupt ..............................................................................................211
13.5 IIC Registers and Control Bits ......................................................................................................212
13.5.1 IIC Address Register (IIC1A) ........................................................................................212
13.5.2 IIC Frequency Divider Register (IIC1F) ........................................................................212
13.5.3 IIC Control Register (IIC1C) .........................................................................................215
13.5.4 IIC Status Register (IIC1S) ............................................................................................216
13.5.5 IIC Data I/O Register (IIC1D) .......................................................................................217
Chapter 14
Analog-to-Digital Converter (ATD) Module
14.1 Introduction ...................................................................................................................................221
14.1.1 Features ..........................................................................................................................221
14.1.2 Modes of Operation .......................................................................................................221
14.1.2.1 Stop Mode .....................................................................................................221
14.1.2.2 Power Down Mode .......................................................................................221
14.1.3 Block Diagram ...............................................................................................................221
14.2 Signal Description .........................................................................................................................222
14.2.1 Overview ........................................................................................................................222
14.2.1.1 Channel Input Pins — AD1P7–AD1P0 ........................................................223
MC9S08GB/GT Data Sheet, Rev. 2.3
14
Freescale Semiconductor
Section Number
14.3
14.4
14.5
14.6
Title
Page
14.2.1.2 ATD Reference Pins — VREFH, VREFL ........................................................223
14.2.1.3 ATD Supply Pins — VDDAD, VSSAD ...........................................................223
Functional Description ..................................................................................................................223
14.3.1 Mode Control .................................................................................................................223
14.3.2 Sample and Hold ............................................................................................................224
14.3.3 Analog Input Multiplexer ..............................................................................................226
14.3.4 ATD Module Accuracy Definitions ...............................................................................226
Resets ............................................................................................................................................229
Interrupts .......................................................................................................................................229
ATD Registers and Control Bits ....................................................................................................229
14.6.1 ATD Control (ATDC) ....................................................................................................230
14.6.2 ATD Status and Control (ATD1SC) ..............................................................................232
14.6.3 ATD Result Data (ATD1RH, ATD1RL) ........................................................................234
14.6.4 ATD Pin Enable (ATD1PE) ...........................................................................................234
Chapter 15
Development Support
15.1 Introduction ...................................................................................................................................235
15.2 Features .........................................................................................................................................236
15.3 Background Debug Controller (BDC) ..........................................................................................237
15.3.1 BKGD Pin Description ..................................................................................................237
15.3.2 Communication Details .................................................................................................238
15.3.3 BDC Commands ............................................................................................................242
15.3.4 BDC Hardware Breakpoint ............................................................................................244
15.4 On-Chip Debug System (DBG) ....................................................................................................245
15.4.1 Comparators A and B ....................................................................................................245
15.4.2 Bus Capture Information and FIFO Operation ..............................................................245
15.4.3 Change-of-Flow Information .........................................................................................246
15.4.4 Tag vs. Force Breakpoints and Triggers ........................................................................246
15.4.5 Trigger Modes ................................................................................................................247
15.4.6 Hardware Breakpoints ...................................................................................................249
15.5 Registers and Control Bits .............................................................................................................249
15.5.1 BDC Registers and Control Bits ....................................................................................249
15.5.1.1 BDC Status and Control Register (BDCSCR) ..............................................250
15.5.1.2 BDC Breakpoint Match Register (BDCBKPT) ............................................251
15.5.2 System Background Debug Force Reset Register (SBDFR) .........................................251
15.5.3 DBG Registers and Control Bits ....................................................................................252
15.5.3.1 Debug Comparator A High Register (DBGCAH) ........................................252
15.5.3.2 Debug Comparator A Low Register (DBGCAL) .........................................252
15.5.3.3 Debug Comparator B High Register (DBGCBH) .........................................252
15.5.3.4 Debug Comparator B Low Register (DBGCBL) ..........................................252
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
15
Section Number
15.5.3.5
15.5.3.6
15.5.3.7
15.5.3.8
15.5.3.9
Title
Page
Debug FIFO High Register (DBGFH) ..........................................................253
Debug FIFO Low Register (DBGFL) ...........................................................253
Debug Control Register (DBGC) ..................................................................254
Debug Trigger Register (DBGT) ..................................................................255
Debug Status Register (DBGS) .....................................................................256
Appendix A
Electrical Characteristics
A.1
A.2
A.3
A.4
A.5
A.6
A.7
A.8
Introduction ...................................................................................................................................259
Absolute Maximum Ratings ..........................................................................................................259
Thermal Characteristics .................................................................................................................260
Electrostatic Discharge (ESD) Protection Characteristics ............................................................261
DC Characteristics .........................................................................................................................261
Supply Current Characteristics ......................................................................................................265
ATD Characteristics ......................................................................................................................269
Internal Clock Generation Module Characteristics .......................................................................271
A.8.1 ICG Frequency Specifications ........................................................................................271
A.9 AC Characteristics .........................................................................................................................273
A.9.1 Control Timing ...............................................................................................................273
A.9.2 Timer/PWM (TPM) Module Timing ..............................................................................274
A.9.3 SPI Timing ......................................................................................................................275
A.10 FLASH Specifications ...................................................................................................................279
Appendix B
Ordering Information and Mechanical Drawings
B.1
B.2
B.3
B.4
B.5
B.6
Ordering Information ....................................................................................................................281
Mechanical Drawings ....................................................................................................................281
64-Pin LQFP Package Drawing ....................................................................................................282
48-Pin QFN Package Drawing ......................................................................................................283
44-Pin QFP Package Drawing .......................................................................................................284
42-Pin SDIP Package Drawing .....................................................................................................285
MC9S08GB/GT Data Sheet, Rev. 2.3
16
Freescale Semiconductor
Chapter 1 Introduction
1.1
Overview
The MC9S08GB/GT 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.
1.2
Features
Features have been organized to reflect:
• Standard features of the HCS08 Family
• Features of the MC9S08GB/GT MCU
1.2.1
•
•
•
•
•
•
•
•
1.2.2
•
•
•
•
•
Standard Features of the HCS08 Family
40-MHz HCS08 CPU (central processor unit)
HC08 instruction set with added BGND instruction
Background debugging system (see also Chapter 15, “Development Support”)
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
Power-saving modes: wait plus three stops
System protection features:
— Optional computer operating properly (COP) reset
— Low-voltage detection with reset or interrupt
— Illegal opcode detection with reset
— Illegal address detection with reset (some devices don’t have illegal addresses)
Features of MC9S08GB/GT Series of MCUs
On-chip in-circuit programmable FLASH memory with block protection and security options (see
Table 1-1 for device specific information)
On-chip random-access memory (RAM) (see Table 1-1 for device specific information)
8-channel, 10-bit analog-to-digital converter (ATD)
Two serial communications interface modules (SCI)
Serial peripheral interface module (SPI)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
17
Chapter 1 Introduction
•
Multiple clock source options:
— Internally generated clock with ±0.2% trimming resolution and ±0.5% deviation across
voltage.
— Crystal
— Resonator, or
— External clock
Inter-integrated circuit bus module to operate up to 100 kbps (IIC)
One 3-channel and one 5-channel 16-bit timer/pulse width modulator (TPM) modules with
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 (TPMx).
8-pin keyboard interrupt module (KBI)
16 high-current pins (limited by package dissipation)
Software selectable pullups on ports when used as input. Selection is on an individual port bit basis.
During output mode, pullups are disengaged.
Internal pullup on RESET and IRQ pin to reduce customer system cost
Up to 56 general-purpose input/output (I/O) pins, depending on package selection
64-pin low-profile quad flat package (LQFP) — MC9S08GBxx
48-pin quad flat package, no lead (QFN) — MC9S08GTxx
44-pin quad flat package (QFP) — MC9S08GTxx
42-pin shrink dual in-line package (SDIP) — MC9S08GTxx
•
•
•
•
•
•
•
•
•
•
•
1.2.3
Devices in the MC9S08GB/GT Series
Table 1-1 lists the devices available in the MC9S08GB/GT series and summarizes the differences among
them.
Table 1-1. Devices in the MC9S08GB/GT Series
1
Device
FLASH
RAM
TPM
I/O
Packages
MC9S08GB60
60K
4K
56
64 LQFP
MC9S08GB32
32K
2K
56
64 LQFP
MC9S08GT60
60K
4K
One 3-channel and one
5-channel, 16-bit timer
One 3-channel and one
5-channel, 16-bit timer
Two 2-channel,
16-bit timers
MC9S08GT32
32K
2K
Two 2-channel,
16-bit timers
MC9S08GT16
16K
1K
Two 2-channel,
16-bit timers
39
36
34
39
36
34
39
36
34
48 QFN1
44 QFP
42 SDIP
48 QFN(1)
44 QFP
42 SDIP
48 QFN(1)
44 QFP
42 SDIP
The 48-pin QFN package has one 3-channel and one 2-channel 16-bit TPM.
MC9S08GB/GT Data Sheet, Rev. 2.3
18
Freescale Semiconductor
MCU Block Diagrams
1.3
MCU Block Diagrams
These block diagrams show the structure of the MC9S08GB/GT MCUs.
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ
enabled (IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown
available when KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 1-1. MC9S08GBxx Block Diagram
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
19
Chapter 1 Introduction
CPU
HCS08 SYSTEM CONTROL
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER FLASH
(GT60 = 61,268 BYTES)
(GT32 = 32,768 BYTES)
(GT16 = 16,384 BYTES)
USER RAM
(GT60 = 4096 BYTES)
(GT32 = 2048 BYTES)
(GT16 = 1024 BYTES)
VDDAD
VSSAD
VREFH
VREFL
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
3-CHANNEL TIMER/PWM
MODULE (TPM1)
(NOTE 8)
PORT C
IIC MODULE (IIC1)
RTI
8
8
PTA7/KBI1P7–
PTA0/KBI1P0
PTB7/AD1P7–
PTB0/AD1P0
PTC6 (NOTE 6)
PTC5 (NOTE 6)
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
NOTES 1, 7
NOTE 1
NOTES 1, 5
PTD4/TPM2CH1
PORT D
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
PTD3/TPM2CH0
NOTE 1
PTD1/TPM1CH1
PTD0/TPM1CH0
PTE5/SPSCK1
5-CHANNEL TIMER/PWM
MODULE (TPM2)
(NOTE 8)
PORT E
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT B
BDC
PORT A
INTERNAL BUS
HCS08 CORE
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
NOTE 1
PTE1/RxD1
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
PTE0/TxD1
PORT G
PTG2/EXTAL
LOW-POWER OSCILLATOR
VDD
VSS
PTG1/XTAL
NOTE 1
PTG0/BKGD/MS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled (IRQPE = 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. High current drive
6. PTC[6:5] are not available on the 42-pin SDIP package.
7. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1).
8. Only two timer channels per TPM are bonded out. All channels are available for use as software compare.
Figure 1-2. MC9S08GTxx Block Diagram
MC9S08GB/GT Data Sheet, Rev. 2.3
20
Freescale Semiconductor
System Clock Distribution
Table 1-2 lists the functional versions of the on-chip modules.
Table 1-2. Block Versions
1.4
Module
Version
Analog-to-Digital Converter (ATD)
3
Internal Clock Generator (ICG)
2
Inter-Integrated Circuit (IIC)
1
Keyboard Interrupt (KBI)
1
Serial Communications Interface (SCI)
1
Serial Peripheral Interface (SPI)
3
Timer Pulse-Width Modulator (TPM)
1
Central Processing Unit (CPU)
2
System Clock Distribution
ICGERCLK
SYSTEM
CONTROL
LOGIC
TPM1
TPM2
IIC1
SCI1
SCI2
SPI1
RTI
FFE
÷2
ICG
FIXED FREQ CLOCK (XCLK)
ICGOUT
÷2
BUSCLK
ICGLCLK*
CPU
BDC
* ICGLCLK is the alternate BDC clock source for the MC9S08GB/GT.
ATD1
RAM
ATD has min and max
frequency requirements.
See Chapter 1, “Introduction”
and Appendix A, “Electrical
Characteristics.
FLASH
FLASH has frequency
requirements for program
and erase operation.
See Appendix A, “Electrical
Characteristics.
Figure 1-3. System Clock Distribution Diagram
Some of the modules inside the MCU have clock source choices. Figure 1-3 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
— 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
21
Chapter 1 Introduction
•
•
•
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 the ICGERCLK.
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
22
Freescale Semiconductor
Chapter 2 Pins and Connections
2.1
Introduction
This section describes signals that connect to package pins. It includes a pinout diagram, a table of signal
properties, and detailed discussion of signals.
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
VSSAD
VDDAD
PTF1
PTF0
PTA7/KBI1P7
PTA6/KBI1P6
PTA5/KBI1P5
PTA4/KBI1P4
63
62
61
60
59
58
57
56
55
54
53
52
51
50
64
PTA3/KBI1P3
PTG5
Device Pin Assignment
PTG6
2.2
49
RESET 1
48 PTA2/KBI1P2
PTG7
2
47
PTA1/KBI1P1
PTC0/TxD2
3
46
PTA0/KBI1P0
PTC1/RxD2
4
45
PTF7
PTC2/SDA1
5
44
PTF6
PTC3/SCL1
6
43
PTF5
PTC4
7
42
VREFL
PTC5
8
41
VREFH
PTC6
9
40
PTB7/AD1P7
PTC7
10
39
PTB6/AD1P6
PTF2
11
38
PTB5/AD1P5
PTF3
12
37
PTB4/AD1P4
PTF4
13
36
PTB3/AD1P3
PTE0/TxD1
14
35
PTB2/AD1P2
PTE1/RxD1
15
34
PTB1/AD1P1
IRQ 16
33 PTB0/AD1P0
18
19
20
21
22
23
24
25
26
27
28
29
30
31
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
VDD
VSS
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTD7/TPM2CH4
32
17
Figure 2-1. MC9S08GBxx in 64-Pin LQFP Package
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
23
PTA2/KBI1P2
37
PTA4/KBI1P4
39
38 PTA3/KBI1P3
PTA5/KBI1P5
40
41 PTA6/KBI1P6
42 PTA7/KBI1P7
VDDAD
44 VSSAD
45 PTG0/BKGD/MS
46 PTG1/XTAL
43
RESET 1
47 PTG2/EXTAL
48 PTG3
Chapter 2 Pins and Connections
36
PTA1/KBI1P1
IRQ 12
25
PTB0/AD1P0
24
PTB1/AD1P1
PTD4/TPM2CH1
26
23
PTE1/RxD1 11
PTD3/TPM2CH0
PTB2/AD1P2
22
27
PTD2/TPM1CH2
PTE0/TxD1 10
21
PTB3/AD1P3
PTD1/TPM1CH1
28
20
PTC7 9
PTD0/TPM1CH0
PTB4/AD1P4
19
29
VDD
PTC6 8
18
30 PTB5/AD1P5
VSS2
PTC5 7
17
31 PTB6/AD1P6
VSS1
PTC4 6
16
32 PTB7/AD1P7
PTE5/SPSCK1
PTC3/SCL1 5
15
33 VREFH
PTE4/MOSI1
PTC2/SDA1 4
14
34 VREFL
PTE3/MISO1
PTC1/RxD2 3
13
35 PTA0/KBI1P0
PTE2/SS1
PTC0/TxD2 2
Figure 2-2. MC9S08GTxx in 48-Pin QFN Package
MC9S08GB/GT Data Sheet, Rev. 2.3
24
Freescale Semiconductor
34 PTA2/KBI1P2
PTA3/KBI1P3
PTA6/KBI1P6
38
35
PTA7/KBI1P7
39
PTA4/KBI1P4
VDDAD
40
36
VSSAD
41
PTA5/KBI1P5
PTG0/BKGD/MS
42
RESET 1
37
PTG1/XTAL
43
44 PTG2/EXTAL
Device Pin Assignment
33 PTA1/KBI1P1
28
PTB6/AD1P6
PTC5
7
27
PTB5/AD1P5
PTC6
8
26
PTB4/AD1P4
PTE0/TxD1
9
25
PTB3/AD1P3
PTE1/RxD1
10
24
PTB2/AD1P2
23
PTB1/AD1P1
PTB0/AD1P0 22
PTE2/SS1 12
IRQ 11
21
6
PTD4/TPM2CH1
PTC4
20
PTB7/AD1P7
PTD3/TPM2CH0
29
19
5
PTD1/TPM1CH1
PTC3/SCL1
18
VREFH
PTD0/TPM1CH0
30
17
4
VDD
PTC2/SDA1
16
VREFL
VSS
31
15
3
PTE5/SPSCK1
PTC1/RxD2
14
PTA0/KBI1P0
PTE4/MOSI1
32
13
2
PTE3/MISO1
PTC0/TxD2
Figure 2-3. MC9S08GTxx in 44-Pin QFP Package
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
25
Chapter 2 Pins and Connections
VDDAD
1
42
PTA7/KBI1P7
VSSAD
2
41
PTA6/KBI1P6
PTG0/BKGD/MS
3
40
PTA5/KBI1P5
PTG1/XTAL
4
39
PTA4/KBI1P4
PTG2/EXTAL
5
38
PTA3/KBI1P3
RESET
6
37
PTA2/KBI1P2
PTC0/TxD2
7
36
PTA1/KBI1P1
PTC1/RXD2
8
35
PTA0/KBI1P0
PTC2/SDA1
9
34
VREFL
PTC3/SCL1
10
33
VREFH
PTC4
11
32
PTB7/AD1P7
PTE0/TxD1
12
31
PTB6/AD1P6
PTE1/RxD1
13
30
PTB5/AD1P5
IRQ
14
29
PTB4/AD1P4
PTE2/SS1
15
28
PTB3/AD1P3
PTE3/MISO1
16
27
PTB2/AD1P2
PTE4/MOSI1
17
26
PTB1/AD1P1
PTE5/SPSCK1
18
25
PTB0/AD1P0
VSS
19
24
PTD4/TPM2CH1
VDD
20
23
PTD3/TPM2CH0
PTD0/TPM1CH0
21
22
PTD1/TPM1CH1
Figure 2-4. MC9S08GTxx in 42-Pin SDIP Package
2.3
Recommended System Connections
Figure 2-5 shows pin connections that are common to almost all MC9S08GB60 application systems.
MC9S08GTxx connections will be similar except for the number of I/O pins available. A more detailed
discussion of system connections follows.
MC9S08GB/GT Data Sheet, Rev. 2.3
26
Freescale Semiconductor
Recommended System Connections
VREFH
CBYAD
0.1 µF
+
3V
MC9S08GBxx
PTA0/KBI1P0
VSSAD
VREFL
VDD
VDD
SYSTEM
POWER
VDDAD
CBLK +
10 µF
CBY
0.1 µF
PTA1/KBI1P1
PTA2/KBI1P2
PORT
A
VSS
NOTE 4
PTA3/KBI1P3
PTA4/KBI1P4
PTA5/KBI1P5
PTA6/KBI1P6
PTA7/KBI1P7
NOTE 1
RF
C1
RS
C2
X1
PTB0/AD1P0
XTAL
NOTE 2
PTB1/AD1P1
PTB2/AD1P2
EXTAL
NOTE 2
PORT
B
PTB3/AD1P3
PTB4/AD1P4
PTB5/AD1P5
BACKGROUND HEADER
VDD
BKGD/MS
NOTE 3
PTB6/AD1P6
I/O AND
PTB7/AD1P7
PERIPHERAL
PTC0/TxD2
INTERFACE TO
PTC1/RxD2
APPLICATION
PTC2/SDA1
RESET
OPTIONAL
MANUAL
RESET
PORT
C
PTC3/SCL1
SYSTEM
PTC4
PTC5
ASYNCHRONOUS
INTERRUPT
INPUT
PTC6
IRQ
PTC7
PTG0/BKDG/MS
PTD0/TPM1CH0
PTG1/XTAL
PTD1/TPM1CH1
PTG2/EXTAL
PTD2/TPM1CH2
NOTES:
1. Not required if
using the internal
oscillator option.
2. These are the
same pins as
PTG1 and PTG2.
3. BKGD/MS is the
same pin as PTG0.
4. The 48-pin QFN
has 2 VSS pins
(VSS1 and VSS2),
both of which must
be connected to
GND.
PTG3
PTG4
PORT
G
PORT
D
PTD3/TPM2CH0
PTD4/TPM2CH1
PTG5
PTD5/TPM2CH2
PTG6
PTD6/TPM2CH3
PTG7
PTD7/TPM2CH4
PTF0
PTE0/TxD1
PTF1
PTE1/RxD1
PTE2/SS1
PTF2
PTF3
PTF4
PORT
F
PORT
E
PTE3/MISO1
PTE4/MOSI1
PTF5
PTE5/SPSCK1
PTF6
PTE6
PTF7
PTE7
Figure 2-5. Basic System Connections
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
27
Chapter 2 Pins and Connections
2.3.1
Power
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 close to the MCU power pins as
practical to suppress high-frequency noise.
VDDAD and VSSAD are the analog power supply pins for the MCU. This voltage source supplies power to
the ATD. A 0.1-µF ceramic bypass capacitor should be located as close to the MCU power pins as practical
to suppress high-frequency noise.
2.3.2
Oscillator
Out of reset, the MCU uses an internally generated clock (self-clocked mode — fSelf_reset) that is
approximately equivalent to an 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 Chapter 7, “Internal Clock Generator (ICG) Module.”
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, and the XTAL output
pin can be used as general I/O.
Refer to Figure 2-5 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
external reset circuitry unnecessary. This pin is normally connected to the standard 6-pin background
MC9S08GB/GT Data Sheet, Rev. 2.3
28
Freescale Semiconductor
Recommended System Connections
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 cycles of fSelf_reset, released, and sampled again approximately 38
cycles of fSelf_reset later. If reset was caused by an internal source such as low-voltage reset or watchdog
timeout, the circuitry expects the reset pin sample to return a logic 1. If the pin is still low at this sample
point, the reset is assumed to be from an external source. The reset circuitry decodes the cause of reset and
records it by setting a corresponding bit in the system control reset status register (SRS).
Never connect any significant capacitance to the reset pin because that would interfere with the circuit and
sequence that detects the source of reset. If an external capacitance prevents the reset pin from rising to a
valid logic 1 before the reset sample point, all resets will appear to be external resets.
2.3.4
Background / Mode Select (PTG0/BKGD/MS)
The background/mode select (BKGD/MS) shares its function with an I/O port pin. While in reset, the 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. When used as an I/O port (PTG0) the pin is limited to output only.
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
General-Purpose I/O and Peripheral Ports
The remaining 55 pins are shared among general-purpose I/O and on-chip peripheral functions such as
timers and serial I/O systems. (Sixteen of these pins are not bonded out on the 48-pin package, twenty of
these pins are not bonded out on the 44-pin package, and twenty-two are not bonded out on the 42-pin
package.) Immediately after reset, all 55 of these pins are configured as high-impedance general-purpose
inputs with internal pullup devices disabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
29
Chapter 2 Pins and Connections
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 section from Table 2-1.
Table 2-1. Pin Sharing References
Port Pins
Alternate
Function
PTA7–PTA0
KBI1P7–KBI1P0
Chapter 2, “Pins and Connections”
PTB7–PTB0
AD1P7–AD1P0
Chapter 14, “Analog-to-Digital Converter (ATD) Module”
PTC7–PTC4
—
Chapter 6, “Parallel Input/Output”
PTC3–PTC2
SCL1–SDA1
Chapter 13, “Inter-Integrated Circuit (IIC) Module”
PTC1–PTC0
RxD2–TxD2
Chapter 11, “Serial Communications Interface (SCI) Module”
PTD7–PTD3
TPM2CH4–
TPM2CH0
Chapter 10, “Timer/PWM (TPM) Module”
PTD2–PTD0
TPM1CH2–
TPM1CH0
Chapter 10, “Timer/PWM (TPM) Module”
PTE7–PTE6
1
Reference1
—
Chapter 6, “Parallel Input/Output”
PTE5
PTE4
PTE3
PTE2
SPSCK1
MISO1
MOSI1
SS1
Chapter 12, “Serial Peripheral Interface (SPI) Module”
PTE1–PTE0
RxD1–TxD1
Chapter 11, “Serial Communications Interface (SCI) Module”
PTF7–PTF0
—
Chapter 6, “Parallel Input/Output”
PTG7–PTG3
—
Chapter 6, “Parallel Input/Output”
PTG2–PTG1
EXTAL–XTAL
Chapter 7, “Internal Clock Generator (ICG) Module”
PTG0
BKGD/MS
Chapter 15, “Development Support”
See this section for information about modules that share these pins.
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 Chapter 6, “Parallel Input/Output” for 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 PTA7–PTA4
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
MC9S08GB/GT Data Sheet, Rev. 2.3
30
Freescale Semiconductor
Recommended System Connections
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.
2.3.6
Signal Properties Summary
Table 2-2 summarizes I/O pin characteristics. These characteristics are determined by the way the
common pin interfaces are hardwired to internal circuits.
Table 2-2. Signal Properties
Pin
Name
High Current
Pin
Output
Slew 1
Pull-Up2
VDD
—
—
—
VSS
—
—
—
VDDAD
—
—
—
VSSAD
—
—
—
VREFH
—
—
—
VREFL
—
—
—
Y
N
Y
Pin contains integrated pullup.
IRQPE must be set to enable IRQ function.
IRQ does not have a clamp diode to VDD. IRQ should
not be driven above VDD.
Pullup/pulldown active when IRQ pin function
enabled. Pullup forced on when IRQ enabled for
falling edges; pulldown forced on when IRQ enabled
for rising edges.
RESET
Dir
I/O
IRQ
I
—
—
Y
PTA0/KBI1P0
I/O
N
SWC
SWC
PTA1/KBI1P1
I/O
N
SWC
SWC
PTA2/KBI1P2
I/O
N
SWC
SWC
PTA3/KBI1P3
I/O
N
SWC
SWC
PTA4/KBI1P4
I/O
N
SWC
SWC
PTA5/KBI1P5
I/O
N
SWC
SWC
PTA6/KBI1P6
I/O
N
SWC
SWC
PTA7/KBI1P7
I/O
N
SWC
SWC
PTB0/AD1P0
I/O
N
SWC
SWC
PTB1/AD1P1
I/O
N
SWC
SWC
PTB2/AD1P2
I/O
N
SWC
SWC
PTB3/AD1P3
I/O
N
SWC
SWC
PTB4/AD1P4
I/O
N
SWC
SWC
PTB5/AD1P5
I/O
N
SWC
SWC
PTB6/AD1P6
I/O
N
SWC
SWC
PTB7/AD1P7
I/O
N
SWC
SWC
PTC0/TxD2
I/O
Y
SWC
SWC
PTC1/RxD2
I/O
Y
SWC
SWC
PTC2/SDA1
I/O
Y
SWC
SWC
PTC3/SCL1
I/O
Y
SWC
SWC
Comments
The 48-pin QFN package has two VSS pins — VSS1
and VSS2.
Pullup/pulldown active when KBI pin function
enabled. Pullup forced on when KBI1Px enabled for
falling edges; pulldown forced on when KBI1Px
enabled for rising edges.
When pin is configured for SCI function, pin is
configured for partial output drive.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
31
Chapter 2 Pins and Connections
Table 2-2. Signal Properties (continued)
1
2
Pin
Name
Dir
High Current
Pin
Output
Slew 1
Pull-Up2
PTC4
I/O
Y
SWC
SWC
PTC5
I/O
Y
SWC
SWC
Not available on 42-pin pkg
PTC6
I/O
Y
SWC
SWC
Not available on 42-pin pkg
PTC7
I/O
Y
SWC
SWC
Not available on 42- or 44-pin pkg
PTD0/TPM1CH0
I/O
N
SWC
SWC
PTD1/TPM1CH1
I/O
N
SWC
SWC
PTD2/TPM1CH2
I/O
N
SWC
SWC
PTD3/TPM2CH0
I/O
N
SWC
SWC
PTD4/TPM2CH1
I/O
N
SWC
SWC
PTD5/TPM2CH2
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTD6/TPM2CH3
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTD7/TPM2CH4
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTE0/TxD1
I/O
N
SWC
SWC
PTE1/RxD1
I/O
N
SWC
SWC
PTE2/SS1
I/O
N
SWC
SWC
PTE3/MISO1
I/O
N
SWC
SWC
Comments
Not available on 42- or 44-pin pkg
PTE4/MOSI1
I/O
N
SWC
SWC
PTE5/SPSCK1
I/O
N
SWC
SWC
PTE6
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTE7
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF0
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF1
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF2
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF3
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF4
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF5
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF6
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTF7
I/O
Y
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTG0/BKGD/MS
O
N
SWC
SWC
Pullup enabled and slew rate disabled when BDM
function enabled.
PTG1/XTAL
I/O
N
SWC
SWC
Pullup and slew rate disabled when XTAL pin
function.
PTG2/EXTAL
I/O
N
SWC
SWC
Pullup and slew rate disabled when EXTAL pin
function.
PTG3
I/O
N
SWC
SWC
Not available on 42-, or 44-pin pkg
PTG4
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTG5
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTG6
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
PTG7
I/O
N
SWC
SWC
Not available on 42-, 44-, or 48-pin pkg
SWC is software controlled slew rate, the register is associated with the respective port.
SWC is software controlled pullup resistor, the register is associated with the respective port.
MC9S08GB/GT Data Sheet, Rev. 2.3
32
Freescale Semiconductor
Chapter 3 Modes of Operation
3.1
Introduction
The operating modes of the MC9S08GB/GT are described in this section. 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
— Stop1 — Full power down of internal circuits for maximum power savings
— 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 MC9S08GB/GT. 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 $FFFE:$FFFF 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
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
33
Chapter 3 Modes of Operation
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 while 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 be executed only 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 MC9S08GB/GT 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 three stop modes is entered upon execution of a STOP instruction when the STOPE bit in the
system option register is set. In all stop modes, all internal clocks are halted. If the STOPE bit is not set
when the CPU executes a STOP instruction, the MCU will not enter any of the stop modes and an illegal
opcode reset is forced. The stop modes are selected by setting the appropriate bits in SPMSC2.
MC9S08GB/GT Data Sheet, Rev. 2.3
34
Freescale Semiconductor
Stop Modes
Table 3-1 summarizes the behavior of the MCU in each of the stop modes.
Table 3-1. Stop Mode Behavior
1
2
Mode
PDC
PPDC
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ATD
Regulator
I/O Pins
RTI
Stop1
1
0
Off
Off
Off
Disabled1
Off
Reset
Off
Stop2
1
1
Off
Standby
Off
Disabled
Standby
States
held
Optionally on
Stop3
0
Don’t
care
Standby
Standby
Off2
Disabled
Standby
States
held
Optionally on
Either ATD stop mode or power-down mode depending on the state of ATDPU.
Crystal oscillator can be configured to run in stop3. Please see the ICG registers.
3.6.1
Stop1 Mode
The stop1 mode provides the lowest possible standby power consumption by causing the internal circuitry
of the MCU to be powered down. Stop1 can be entered only if the LVD circuit is not enabled in stop modes
(either LVDE or LVDSE not set).
When the MCU is in stop1 mode, all internal circuits that are powered from the voltage regulator are turned
off. The voltage regulator is in a low-power standby state, as is the ATD.
Exit from stop1 is performed by asserting either of the wake-up pins on the MCU: RESET or IRQ. IRQ is
always an active low input when the MCU is in stop1, regardless of how it was configured before entering
stop1.
Entering stop1 mode automatically asserts LVD. Stop1 cannot be exited until VDD > VLVDH/L rising (VDD
must rise above the LVI rearm voltage).
Upon wake-up from stop1 mode, the MCU will start up as from a power-on reset (POR). The CPU will
take the reset vector.
3.6.2
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. Stop2 can be entered only if the LVD circuit is not enabled in stop
modes (either LVDE or LVDSE not set).
Before entering stop2 mode, the user must save the contents of the I/O port registers, as well as any other
memory-mapped registers 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 ATD. 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 1 is written to PPDACK in SPMSC2.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
35
Chapter 3 Modes of Operation
Exit from stop2 is performed by asserting either of the wake-up pins: RESET or IRQ, or by an RTI
interrupt. IRQ 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 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
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.
3.6.3
Stop3 Mode
Upon entering the stop3 mode, all of the clocks in the MCU, including the oscillator itself, are halted. The
ICG is turned off, the ATD is disabled, and the voltage regulator is put in standby. 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 performed by asserting RESET, an asynchronous interrupt pin, or through the real-time
interrupt. The asynchronous interrupt pins are the IRQ or KBI pins.
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.
3.6.4
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 the Chapter 15, “Development Support,” section 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,
MC9S08GB/GT Data Sheet, Rev. 2.3
36
Freescale Semiconductor
Stop Modes
the voltage regulator does not enter its low-power standby state but maintains full internal regulation. If
the user attempts to enter either stop1 or 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 the device enters background debug mode, all
background commands are available. The table below summarizes the behavior of the MCU in stop when
entry into the background debug mode is enabled.
Table 3-2. BDM Enabled Stop Mode Behavior
1
Mode
PDC
PPDC
Stop3
Don’t
care
Don’t
care
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ATD
Regulator
I/O Pins
RTI
Standby
Standby
Active
Disabled1
Active
States
held
Optionally on
Either ATD stop mode or power-down mode depending on the state of ATDPU.
3.6.5
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 in SPMSC1 when
the CPU executes a STOP instruction, then the voltage regulator remains active during stop mode. If the
user attempts to enter either stop1 or stop2 with the LVD enabled for stop (LVDSE = 1), the MCU will
instead enter stop3. The table below summarizes the behavior of the MCU in stop when the LVD is
enabled.
Table 3-3. LVD Enabled Stop Mode Behavior
1
Mode
PDC
PPDC
Stop3
Don’t
care
Don’t
care
CPU, Digital
Peripherals,
FLASH
RAM
ICG
ATD
Regulator
I/O Pins
RTI
Standby
Standby
Standby
Disabled1
Active
States
held
Optionally on
Either ATD stop mode or power-down mode depending on the state of ATDPU.
3.6.6
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 to the background debug logic continue to operate,
clocks to the peripheral systems are halted to reduce power consumption. Refer to Section 3.6.1, “Stop1
Mode,” Section 3.6.2, “Stop2 Mode,” and Section 3.6.3, “Stop3 Mode,” for specific information on system
behavior in stop modes.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
37
Chapter 3 Modes of Operation
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.
• If the MCU is configured to go into stop1 mode, all I/O pins are forced to their default reset state
upon entry into 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.
• All registers will be reset upon wake-up from stop1 and the contents of RAM are not preserved.
The MCU must be initialized as upon reset. The contents of the FLASH memory are nonvolatile
and are preserved in any of the stop modes.
ICG — In stop3 mode, the ICG enters its low-power standby state. Either the oscillator or the internal
reference may be kept running when the ICG is in standby by setting the appropriate control bit. In both
stop2 and stop1 modes, the ICG is turned off. Neither the oscillator nor the internal reference can be kept
running in stop2 or stop1, even if enabled within the ICG module.
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 or stop1 mode, the TPM modules will be reset
upon wake-up from stop and must be reinitialized.
ATD — When the MCU enters stop mode, the ATD will enter a low-power standby state. No conversion
operation will occur while in stop. If the MCU is configured to go into stop2 or stop1 mode, the ATD will
be reset upon wake-up from stop and must be reinitialized.
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 stop1 and stop2 and must be reinitialized
after waking up from either of these modes.
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 or stop1 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 or stop1 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 or stop1 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 any
of the stop modes unless the LVD is enabled in stop mode or BDM is enabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
38
Freescale Semiconductor
Chapter 4 Memory
4.1
MC9S08GB/GT Memory Map
As shown in Figure 4-1, on-chip memory in the MC9S08GB/GT series of MCUs 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 ($0000 through $007F)
• High-page registers ($1800 through $182B)
• Nonvolatile registers ($FFB0 through $FFBF)
DIRECT PAGE REGISTERS
$0000
$007F
$0080
$0000
DIRECT PAGE REGISTERS
$007F
$0080
RAM
2048 BYTES
RAM
4096 BYTES
$0000
DIRECT PAGE REGISTERS
RAM 1024 BYTES
$007F
$0080
$047F
$0480
$087F
$0880
UNIMPLEMENTED
$107F
$1080
UNIMPLEMENTED
4992 BYTES
3968 BYTES
FLASH
1920 BYTES
$17FF
$1800
$17FF
$1800
HIGH PAGE REGISTERS
HIGH PAGE REGISTERS
$182B
$182C
$17FF
$1800
HIGH PAGE REGISTERS
$182B
$182C
$182B
$182C
UNIMPLEMENTED
26580 BYTES
$7FFF
$8000
UNIMPLEMENTED
42964 BYTES
FLASH
59348 BYTES
FLASH
$BFFF
$C000
32768 BYTES
FLASH
16384 BYTES
$FFFF
$FFFF
MC9S08GB60/MC9S08GT60
MC9S08GB32/MC9S08GT32
$FFFF
MC9S08GT16
Figure 4-1. MC9S08GB/GT Memory Map
4.1.1
Reset and Interrupt Vector Assignments
Table 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 MC9S08GB/GT. For more details about
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
39
Chapter 4 Memory
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
$FFC0:FFC1
Unused Vector Space
(available for user program)
$FFCA:FFCB
$FFCC:FFCD
RTI
Vrti
$FFCE:FFCF
IIC
Viic1
$FFD0:FFD1
ATD Conversion
Vatd1
$FFD2:FFD3
Keyboard
Vkeyboard1
$FFD4:FFD5
SCI2 Transmit
Vsci2tx
$FFD6:FFD7
SCI2 Receive
Vsci2rx
$FFD8:FFD9
SCI2 Error
Vsci2err
$FFDA:FFDB
SCI1 Transmit
Vsci1tx
$FFDC:FFDD
SCI1 Receive
Vsci1rx
$FFDE:FFDF
SCI1 Error
Vsci1err
$FFE0:FFE1
SPI
Vspi1
$FFE2:FFE3
TPM2 Overflow
Vtpm2ovf
$FFE4:FFE5
TPM2 Channel 4
Vtpm2ch4
$FFE6:FFE7
TPM2 Channel 3
Vtpm2ch3
$FFE8:FFE9
TPM2 Channel 2
Vtpm2ch2
$FFEA:FFEB
TPM2 Channel 1
Vtpm2ch1
$FFEC:FFED
TPM2 Channel 0
Vtpm2ch0
$FFEE:FFEF
TPM1 Overflow
Vtpm1ovf
$FFF0:FFF1
TPM1 Channel 2
Vtpm1ch2
$FFF2:FFF3
TPM1 Channel 1
Vtpm1ch1
$FFF4:FFF5
TPM1 Channel 0
Vtpm1ch0
$FFF6:FFF7
ICG
Vicg
$FFF8:FFF9
Low Voltage Detect
Vlvd
$FFFA:FFFB
IRQ
Virq
$FFFC:FFFD
SWI
Vswi
$FFFE:FFFF
Reset
Vreset
MC9S08GB/GT Data Sheet, Rev. 2.3
40
Freescale Semiconductor
Register Addresses and Bit Assignments
4.2
Register Addresses and Bit Assignments
The registers in the MC9S08GB/GT are divided into these three groups:
• Direct-page registers are located in the first 128 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 $1800 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
$FFB0–$FFBF.
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
41
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 1 of 3)
Address
Register Name
$0000
$0001
$0002
$0003
$0004
$0005
$0006
$0007
$0008
$0009
$000A
$000B
$000C
$000D
$000E
$000F
$0010
$0011
$0012
$0013
$0014
PTAD
PTAPE
PTASE
PTADD
PTBD
PTBPE
PTBSE
PTBDD
PTCD
PTCPE
PTCSE
PTCDD
PTDD
PTDPE
PTDSE
PTDDD
PTED
PTEPE
PTESE
PTEDD
IRQSC
$0015
$0016
$0017
$0018
$0019
$001A
$001B
$001C
$001D
$001E
$001F
$0020
$0021
$0022
$0023
$0024
$0025
$0026
$0027
Reserved
KBI1SC
KBI1PE
SCI1BDH
SCI1BDL
SCI1C1
SCI1C2
SCI1S1
SCI1S2
SCI1C3
SCI1D
SCI2BDH
SCI2BDL
SCI2C1
SCI2C2
SCI2S1
SCI2S2
SCI2C3
SCI2D
Bit 7
6
5
4
3
2
1
Bit 0
PTAD7
PTAPE7
PTASE7
PTADD7
PTBD7
PTBPE7
PTBSE7
PTBDD7
PTCD7
PTCPE7
PTCSE7
PTCDD7
PTDD7
PTDPE7
PTDSE7
PTDDD7
PTED7
PTEPE7
PTESE7
PTEDD7
PTAD6
PTAPE6
PTASE6
PTADD6
PTBD6
PTBPE6
PTBSE6
PTBDD6
PTCD6
PTCPE6
PTCSE6
PTCDD6
PTDD6
PTDPE6
PTDSE6
PTDDD6
PTED6
PTEPE6
PTESE6
PTEDD6
PTAD5
PTAPE5
PTASE5
PTADD5
PTBD5
PTBPE5
PTBSE5
PTBDD5
PTCD5
PTCPE5
PTCSE5
PTCDD5
PTDD5
PTDPE5
PTDSE5
PTDDD5
PTED5
PTEPE5
PTESE5
PTEDD5
PTAD4
PTAPE4
PTASE4
PTADD4
PTBD4
PTBPE4
PTBSE4
PTBDD4
PTCD4
PTCPE4
PTCSE4
PTCDD4
PTDD4
PTDPE4
PTDSE4
PTDDD4
PTED4
PTEPE4
PTESE4
PTEDD4
PTAD3
PTAPE3
PTASE3
PTADD3
PTBD3
PTBPE3
PTBSE3
PTBDD3
PTCD3
PTCPE3
PTCSE3
PTCDD3
PTDD3
PTDPE3
PTDSE3
PTDDD3
PTED3
PTEPE3
PTESE3
PTEDD3
PTAD2
PTAPE2
PTASE2
PTADD2
PTBD2
PTBPE2
PTBSE2
PTBDD2
PTCD2
PTCPE2
PTCSE2
PTCDD2
PTDD2
PTDPE2
PTDSE2
PTDDD2
PTED2
PTEPE2
PTESE2
PTEDD2
PTAD1
PTAPE1
PTASE1
PTADD1
PTBD1
PTBPE1
PTBSE1
PTBDD1
PTCD1
PTCPE1
PTCSE1
PTCDD1
PTDD1
PTDPE1
PTDSE1
PTDDD1
PTED1
PTEPE1
PTESE1
PTEDD1
PTAD0
PTAPE0
PTASE0
PTADD0
PTBD0
PTBPE0
PTBSE0
PTBDD0
PTCD0
PTCPE0
PTCSE0
PTCDD0
PTDD0
PTDPE0
PTDSE0
PTDDD0
PTED0
PTEPE0
PTESE0
PTEDD0
0
—
KBEDG7
KBIPE7
0
SBR7
LOOPS
TIE
TDRE
0
R8
Bit 7
0
SBR7
LOOPS
TIE
TDRE
0
R8
Bit 7
0
—
KBEDG6
KBIPE6
0
SBR6
SCISWAI
TCIE
TC
0
T8
6
0
SBR6
SCISWAI
TCIE
TC
0
T8
6
IRQEDG
—
KBEDG5
KBIPE5
0
SBR5
RSRC
RIE
RDRF
0
TXDIR
5
0
SBR5
RSRC
RIE
RDRF
0
TXDIR
5
IRQPE
—
KBEDG4
KBIPE4
SBR12
SBR4
M
ILIE
IDLE
0
0
4
SBR12
SBR4
M
ILIE
IDLE
0
0
4
IRQF
—
KBF
KBIPE3
SBR11
SBR3
WAKE
TE
OR
0
ORIE
3
SBR11
SBR3
WAKE
TE
OR
0
ORIE
3
IRQACK
—
KBACK
KBIPE2
SBR10
SBR2
ILT
RE
NF
0
NEIE
2
SBR10
SBR2
ILT
RE
NF
0
NEIE
2
IRQIE
—
KBIE
KBIPE1
SBR9
SBR1
PE
RWU
FE
0
FEIE
1
SBR9
SBR1
PE
RWU
FE
0
FEIE
1
IRQMOD
—
KBIMOD
KBIPE0
SBR8
SBR0
PT
SBK
PF
RAF
PEIE
Bit 0
SBR8
SBR0
PT
SBK
PF
RAF
PEIE
Bit 0
MC9S08GB/GT Data Sheet, Rev. 2.3
42
Freescale Semiconductor
Register Addresses and Bit Assignments
Table 4-2. Direct-Page Register Summary (Sheet 2 of 3)
Address
Register Name
$0028
$0029
$002A
$002B
$002C
$002D
$002E
$002F
$0030
$0031
$0032
$0033
$0034
$0035
SPI1C1
SPI1C2
SPI1BR
SPI1S
Reserved
SPI1D
Reserved
Reserved
TPM1SC
TPM1CNTH
TPM1CNTL
TPM1MODH
TPM1MODL
TPM1C0SC
$0036
$0037
$0038
$0039
$003A
$003B
$003C
$003D
$003E–
$003F
$0040
$0041
$0042
$0043
$0044
$0045
$0046
$0047
$0048
$0049
$004A
$004B
$004C
$004D
$004E
TPM1C0VH
TPM1C0VL
TPM1C1SC
TPM1C1VH
TPM1C1VL
TPM1C2SC
TPM1C2VH
TPM1C2VL
Reserved
PTFD
PTFPE
PTFSE
PTFDD
PTGD
PTGPE
PTGSE
PTGDD
ICGC1
ICGC2
ICGS1
ICGS2
ICGFLTU
ICGFLTL
ICGTRM
Bit 7
6
5
4
3
2
1
Bit 0
SPIE
0
0
SPRF
0
Bit 7
0
0
TOF
Bit 15
Bit 7
Bit 15
Bit 7
CH0F
SPE
0
SPPR2
0
0
6
0
0
TOIE
14
6
14
6
CH0IE
SPTIE
0
SPPR1
SPTEF
0
5
0
0
CPWMS
13
5
13
5
MS0B
MSTR
MODFEN
SPPR0
MODF
0
4
0
0
CLKSB
12
4
12
4
MS0A
CPOL
BIDIROE
0
0
0
3
0
0
CLKSA
11
3
11
3
ELS0B
CPHA
0
SPR2
0
0
2
0
0
PS2
10
2
10
2
ELS0A
SSOE
SPISWAI
SPR1
0
0
1
0
0
PS1
9
1
9
1
LSBFE
SPC0
SPR0
0
0
Bit 0
0
0
PS0
Bit 8
Bit 0
Bit 8
Bit 0
13
5
MS1B
13
5
MS2B
13
5
—
—
PTFD5
PTFPE5
PTFSE5
PTFDD5
PTGD5
PTGPE5
PTGSE5
PTGDD5
REFS
MFD
REFST
0
0
12
11
4
3
MS1A
ELS1B
12
11
4
3
MS2A
ELS2B
12
11
4
3
—
—
—
—
PTFD4
PTFD3
PTFPE4
PTFPE3
PTFSE4
PTFSE3
PTFDD4
PTFDD3
PTGD4
PTGD3
PTGPE4
PTGPE3
PTGSE4
PTGSE3
PTGDD4 PTGDD3
CLKS
LOCRE
LOLS
LOCK
0
0
0
FLT
TRIM
0
9
1
0
9
1
0
9
1
—
—
PTFD1
PTFPE1
PTFSE1
PTFDD1
PTGD1
PTGPE1
PTGSE1
PTGDD1
0*
RFD
ERCS
0
0
Bit 8
Bit 0
0
Bit 8
Bit 0
0
Bit 8
Bit 0
—
—
PTFD0
PTFPE0
PTFSE0
PTFDD0
PTGD0
PTGPE0
PTGSE0
PTGDD0
0
Bit 15
14
Bit 7
6
CH1F
CH1IE
Bit 15
14
Bit 7
6
CH2F
CH2IE
Bit 15
14
Bit 7
6
—
—
—
—
PTFD7
PTFD6
PTFPE7
PTFPE6
PTFSE7
PTFSE6
PTFDD7
PTFDD6
PTGD7
PTGD6
PTGPE7
PTGPE6
PTGSE7
PTGSE6
PTGDD7 PTGDD6
0
RANGE
LOLRE
CLKST
0
0
0
0
10
2
ELS1A
10
2
ELS2A
10
2
—
—
PTFD2
PTFPE2
PTFSE2
PTFDD2
PTGD2
PTGPE2
PTGSE2
PTGDD2
OSCSTEN
LOCS
0
ICGIF
DCOS
FLT
* This bit is reserved for Freescale Semiconductor internal use only. Always write a 0 to this bit.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
43
Chapter 4 Memory
Table 4-2. Direct-Page Register Summary (Sheet 3 of 3)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
$004F
Reserved
0
0
0
0
$0050
$0051
$0052
$0053
$0054
$0055–
$0057
$0058
$0059
$005A
$005B
ATD1C
ATD1SC
ATD1RH
ATD1RL
ATD1PE
ATDPU
CCF
Bit 7
Bit 7
ATDPE7
—
—
DJM
ATDIE
6
6
ATDPE6
—
—
RES8
ATDCO
5
5
ATDPE5
—
—
SGN
$005C
$005D–
$005F
$0060
$0061
$0062
$0063
$0064
$0065
$0066
$0067
$0068
$0069
$006A
$006B
$006C
$006D
$006E
$006F
$0070
$0071
$0072
$0073
$0074–
$007F
Reserved
IIC1A
IIC1F
IIC1C
IIC1S
TPM2SC
TPM2CNTH
TPM2CNTL
TPM2MODH
TPM2MODL
TPM2C0SC
TPM2C0VH
TPM2C0VL
TPM2C1SC
TPM2C1VH
TPM2C1VL
TPM2C2SC
TPM2C2VH
TPM2C2VL
TPM2C3SC
TPM2C3VH
TPM2C3VL
TPM2C4SC
TPM2C4VH
TPM2C4VL
Reserved
3
3
ATDPE3
—
—
MULT
IICEN
TCF
Bit 0
Bit 0
ATDPE0
—
—
0
ICR
IICIE
IAAS
MST
BUSY
IIC1D
Reserved
4
4
ATDPE4
—
—
ADDR
PRS
ATDCH
2
1
2
1
ATDPE2
ATDPE1
—
—
—
—
TX
ARBL
TXAK
RSTA
0
0
0
SRW
IICIF
RXAK
—
—
CLKSA
11
3
11
3
ELS0B
11
3
ELS1B
11
3
ELS2B
11
3
ELS3B
11
3
ELS4B
11
3
—
—
—
—
PS2
10
2
10
2
ELS0A
10
2
ELS1A
10
2
ELS2A
10
2
ELS3A
10
2
ELS4A
10
2
—
—
—
—
PS1
9
1
9
1
0
9
1
0
9
1
0
9
1
0
9
1
0
9
1
—
—
—
—
PS0
Bit 8
Bit 0
Bit 8
Bit 0
0
Bit 8
Bit 0
0
Bit 8
Bit 0
0
Bit 8
Bit 0
0
Bit 8
Bit 0
0
Bit 8
Bit 0
—
—
DATA
—
—
TOF
Bit 15
Bit 7
Bit 15
Bit 7
CH0F
Bit 15
Bit 7
CH1F
Bit 15
Bit 7
CH2F
Bit 15
Bit 7
CH3F
Bit 15
Bit 7
CH4F
Bit 15
Bit 7
—
—
—
—
TOIE
14
6
14
6
CH0IE
14
6
CH1IE
14
6
CH2IE
14
6
CH3IE
14
6
CH4IE
14
6
—
—
—
—
CPWMS
13
5
13
5
MS0B
13
5
MS1B
13
5
MS2B
13
5
MS3B
13
5
MS4B
13
5
—
—
—
—
CLKSB
12
4
12
4
MS0A
12
4
MS1A
12
4
MS2A
12
4
MS3A
12
4
MS4A
12
4
—
—
MC9S08GB/GT Data Sheet, Rev. 2.3
44
Freescale Semiconductor
Register Addresses and Bit Assignments
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 $1800.
Table 4-3. High-Page Register Summary
Address
$1800
$1801
$1802
$1803 –
$1805
$1806
$1807
$1808
$1809
$180A
$180B–
$180F
$1810
$1811
$1812
$1813
$1814
$1815
$1816
$1817
$1818
$1819–
$181F
$1820
$1821
$1822
$1823
$1824
$1825
$1826
$1827–
$182B
Register Name
SRS
SBDFR
SOPT
Reserved
SDIDH
SDIDL
SRTISC
SPMSC1
SPMSC2
Reserved
DBGCAH
DBGCAL
DBGCBH
DBGCBL
DBGFH
DBGFL
DBGC
DBGT
DBGS
Reserved
FCDIV
FOPT
Reserved
FCNFG
FPROT
FSTAT
FCMD
Reserved
Bit 7
6
5
4
3
2
1
Bit 0
POR
0
COPE
—
—
REV3
ID7
RTIF
LVDF
LVWF
PIN
0
COPT
—
—
REV2
ID6
RTIACK
LVDACK
LVWACK
COP
0
STOPE
—
—
REV1
ID5
RTICLKS
LVDIE
LVDV
ILOP
0
—
—
—
REV0
ID4
RTIE
LVDRE
LVWV
0
0
0
—
—
ID11
ID3
0
LVDSE
PPDF
ICG
0
0
—
—
ID10
ID2
RTIS2
LVDE
PPDACK
LVD
0
BKGDPE
—
—
ID9
ID1
RTIS1
0
PDC
0
BDFR
—
—
—
ID8
ID0
RTIS0
0
PPDC
—
—
Bit 15
Bit 7
Bit 15
Bit 7
Bit 15
Bit 7
DBGEN
TRGSEL
AF
—
—
DIVLD
KEYEN
—
0
FPOPEN
FCBEF
FCMD7
—
—
—
—
14
6
14
6
14
6
ARM
BEGIN
BF
—
—
PRDIV8
FNORED
—
0
FPDIS
FCCF
FCMD6
—
—
—
—
13
5
13
5
13
5
TAG
0
ARMF
—
—
DIV5
0
—
KEYACC
FPS2
FPVIOL
FCMD5
—
—
—
—
12
4
12
4
12
4
BRKEN
0
0
—
—
DIV4
0
—
0
FPS1
FACCERR
FCMD4
—
—
—
—
11
3
11
3
11
3
RWA
TRG3
CNT3
—
—
DIV3
0
—
0
FPS0
0
FCMD3
—
—
—
—
10
2
10
2
10
2
RWAEN
TRG2
CNT2
—
—
DIV2
0
—
0
0
FBLANK
FCMD2
—
—
—
—
9
1
9
1
9
1
RWB
TRG1
CNT1
—
—
DIV1
SEC01
—
0
0
0
FCMD1
—
—
—
—
Bit 8
Bit 0
Bit 8
Bit 0
Bit 8
Bit 0
RWBEN
TRG0
CNT0
—
—
DIV0
SEC00
—
0
0
0
FCMD0
—
—
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
45
Chapter 4 Memory
Table 4-4. Nonvolatile Register Summary
Address
$FFB0 –
$FFB7
$FFB8 –
$FFBC
$FFBD
$FFBE
$FFBF
1
Register Name
Bit 7
6
5
NVBACKKEY
Reserved
NVPROT
Reserved1
NVOPT
4
3
2
1
Bit 0
—
—
0
—
0
—
—
0
—
SEC01
—
—
0
—
SEC00
8-Byte Comparison Key
—
—
FPOPEN
—
KEYEN
—
—
FPDIS
—
FNORED
—
—
FPS2
—
0
—
—
FPS1
—
0
—
—
FPS0
—
0
This location is 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 MC9S08GB/GT includes static RAM. The locations in RAM below $0100 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 or after
wakeup from stop1, 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 $00FF. In the
MC9S08GB/GT, 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.
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
46
Freescale Semiconductor
FLASH
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
— MC9S08GB60/MC9S08GT60 — 61268 bytes (120 pages of 512 bytes each)
— MC9S08GB32/MC9S08GT32— 32768 bytes (64 pages of 512 bytes each)
— MC9S08GT16 — 16384 bytes (32 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 Table 4.6.1). 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 is 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.
Table 4-5. Program and Erase Times
Parameter
1
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
Excluding start/end overhead
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
47
Chapter 4 Memory
4.4.3
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 blocks 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 in 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 ($05), byte program ($20), burst program ($25), page erase ($40), and mass erase ($41).
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 adhered to, or the command will not be accepted. This minimizes
the possibility of any unintended change 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
burst programming. The FCDIV register must be initialized before using any FLASH commands. This
must be done only once following a reset.
MC9S08GB/GT Data Sheet, Rev. 2.3
48
Freescale Semiconductor
FLASH
START
0
FACCERR ?
CLEAR ERROR
(1)
WRITE TO FCDIV(1)
Only required once
after reset.
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND TO FCMD
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (2)
FPVIO OR
FACCERR ?
(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 the following two conditions are met:
1. The next burst program command has been queued before the current program operation has
completed.
2. 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
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
49
Chapter 4 Memory
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.
START
0
FACCERR ?
1
CLEAR ERROR
WRITE TO FCDIV(1)
(1) Only required once
after reset.
FCBEF ?
0
1
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND TO FCMD
WRITE 1 TO FCBEF
TO LAUNCH COMMAND
AND CLEAR FCBEF (2)
FPVIO OR
FACCERR ?
(2) Wait at least four bus cycles before
checking FCBEF or FCCF.
YES
ERROR EXIT
NO
YES
NEW BURST COMMAND ?
NO
0
FCCF ?
1
DONE
Figure 4-3. FLASH Burst Program Flowchart
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
50
Freescale Semiconductor
FLASH
•
•
•
•
•
•
•
•
•
•
4.4.6
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 ($05, $20, $25, $40, or $41) to
FCMD
Accessing (read or write) 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 ($20, $25, or $40) 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
FLASH Block Protection
Block protection prevents program or erase changes for FLASH memory locations in a designated address
range. Mass erase is disabled when any block of FLASH is protected. The MC9S08GB/GT allows a block
of memory at the end of FLASH, and/or the entire FLASH memory to be block protected. A disable
control bit and a 3-bit control field, allows the user to set the size of this block. A separate control bit allows
block protection of the entire FLASH memory array. All seven of these control bits are located in the
FPROT register (see Section 4.6.4, “FLASH Protection Register (FPROT and NVPROT)”).
At reset, the high-page register (FPROT) is loaded with the contents of the NVPROT location which is in
the nonvolatile register block of the FLASH memory. The value in FPROT cannot be changed directly
from application software so a runaway program cannot alter the block protection settings. If the last 512
bytes of FLASH which includes the NVPROT register is protected, the application program cannot alter
the block protection settings (intentionally or unintentionally). The FPROT control bits can be written by
background debug commands to allow a way to erase a protected FLASH memory.
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
51
Chapter 4 Memory
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 $FFBF 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 $FFBD. All of
the interrupt vectors (memory locations $FFC0–$FFFD) are redirected, while the reset vector
($FFFE:FFFF) is not. When more than 32K of memory is protected, vector redirection must not be
enabled.
For example, if 512 bytes of FLASH are protected, the protected address region is from $FE00 through
$FFFF. The interrupt vectors ($FFC0–$FFFD) are redirected to the locations $FDC0–$FDFD. Now, if an
SPI interrupt is taken for instance, the values in the locations $FDE0:FDE1 are used for the vector instead
of the values in the locations $FFE0: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 MC9S08GB/GT 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 while the other three combinations engage security. Notice the erased state (1:1)
makes 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
MC9S08GB/GT Data Sheet, Rev. 2.3
52
Freescale Semiconductor
FLASH Registers and Control Bits
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 RAM, so it cannot be entered through background commands
without the cooperation of a secure user program. The FLASH memory cannot be accessed by read
operations while KEYACC is set.
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 just 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 performing 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.
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 that 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
53
Chapter 4 Memory
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.
Bit 7
Read:
6
5
4
3
2
1
Bit 0
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
0
0
0
0
0
0
0
DIVLD
Write:
Reset:
0
= Unimplemented or Reserved
Figure 4-4. FLASH Clock Divider Register (FCDIV)
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.
1 = FCDIV has been written since reset; erase and program operations enabled for FLASH.
0 = FCDIV has not been written since reset; erase and program operations disabled for FLASH.
PRDIV8 — Prescale (Divide) FLASH Clock by 8
1 = Clock input to the FLASH clock divider is the bus rate clock divided by 8.
0 = Clock input to the FLASH clock divider is the bus rate clock.
DIV5:DIV0 — 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.
if PRDIV8 = 0 — fFCLK = fBus ÷ ([DIV5:DIV0] + 1)
Eqn. 4-1
if PRDIV8 = 1 — fFCLK = fBus ÷ (8 × ([DIV5:DIV0] + 1))
Eqn. 4-2
Table 4-6 shows the appropriate values for PRDIV8 and DIV5:DIV0 for selected bus frequencies.
MC9S08GB/GT Data Sheet, Rev. 2.3
54
Freescale Semiconductor
FLASH Registers and Control Bits
Table 4-6. FLASH Clock Divider Settings
4.6.2
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
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.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
Write:
Reset:
This register is loaded from nonvolatile location NVOPT during reset.
= Unimplemented or Reserved
Figure 4-5. FLASH Options Register (FOPT)
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.”
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.
0 = No backdoor key access allowed.
FNORED — Vector Redirection Disable
When this bit is 1, vector redirection is disabled.
1 = Vector redirection disabled.
0 = Vector redirection enabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
55
Chapter 4 Memory
SEC01:SEC00 — Security State Code
This 2-bit field determines the security state of the MCU as shown in Table 4-7. 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.”
Table 4-7. 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.
Read:
Bit 7
6
0
0
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
0
0
KEYACC
Write:
Reset:
0
0
0
= Unimplemented or Reserved
Figure 4-6. FLASH Configuration Register (FCNFG)
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.”
1 = Writes to NVBACKKEY ($FFB0–$FFB7) are interpreted as comparison key writes.
Reads of the FLASH return invalid data.
0 = Writes to $FFB0–$FFB7 are interpreted as the start of a FLASH programming or erase
command.
4.6.4
FLASH Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT is copied from FLASH into FPROT. Bits 0,
1, and 2 are not used and each always reads as 0. This register may be read at any time, but user program
writes have no meaning or effect. Background debug commands can write to FPROT.
MC9S08GB/GT Data Sheet, Rev. 2.3
56
Freescale Semiconductor
FLASH Registers and Control Bits
Bit 7
Read: FPOPEN
Write:
Reset:
1
6
5
4
3
2
1
Bit 0
FPDIS
FPS2
FPS1
FPS0
0
0
0
(1)
(1)
(1)
(1)
This register is loaded from nonvolatile location NVPROT during reset.
= Unimplemented or Reserved
1
Background commands can be used to change the contents of these bits in FPROT.
Figure 4-7. FLASH Protection Register (FPROT)
FPOPEN — Open Unprotected FLASH for Program/Erase
1 = Any FLASH location, not otherwise block protected or secured, may be erased or programmed.
0 = Entire FLASH memory is block protected (no program or erase allowed).
FPDIS — FLASH Protection Disable
1 = No FLASH block is protected.
0 = FLASH block specified by FPS2:FPS0 is block protected (program and erase not allowed).
FPS2:FPS1:FPS0 — FLASH Protect Size Selects
When FPDIS = 0, this 3-bit field determines the size of a protected block of FLASH locations at the
high address end of the FLASH (see Table 4-8). Protected FLASH locations cannot be erased or
programmed.
Table 4-8. High Address Protected Block
FPS2:FPS1:FPS0
Protected Address Range
Protected Block Size
Redirected Vectors1
0:0:0
$FE00–$FFFF
512 bytes
$FDC0–$FDFD2
0:0:1
$FC00–$FFFF
1024 bytes
$FBC0–$FBFD
0:1:0
$F800–$FFFF
2048 bytes
$F7C0–$F7FD
0:1:1
$F000–$FFFF
4096 bytes
$EFC0–$EFFD
1:0:0
$E000–$FFFF
8192 bytes
$DFC0–$DFFD
1:0:1
$C000–$FFFF
16384 bytes
$BFC0–$BFFD3
1:1:0
$8000–$FFFF
32768 bytes
$7FC0–$7FFD4
1:1:1
$8000–$FFFF
32768 bytes
$7FC0–$7FFD4
1
No redirection if FPOPEN = 0, or FNORED = 1.
Reset vector is not redirected.
3
32K and 60K devices only.
4
60K devices only.
2
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
57
Chapter 4 Memory
4.6.5
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.
Bit 7
6
Read:
5
4
FCCF
FCBEF
3
2
1
Bit 0
0
FBLANK
0
0
0
0
0
0
FPVIOL FACCERR
Write:
Reset:
1
1
0
0
= Unimplemented or Reserved
Figure 4-8. FLASH Status Register (FSTAT)
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 1 to it or when a burst program command is transferred to the array for
programming. Only burst program commands can be buffered.
1 = A new burst program command may be written to the command buffer.
0 = Command buffer is full (not ready for additional commands).
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.
1 = All commands complete
0 = Command in progress
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.
1 = An attempt was made to erase or program a protected location.
0 = No protection violation.
FACCERR — Access Error Flag
FACCERR is set automatically when the proper command sequence is not followed 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.
1 = An access error has occurred.
0 = No access error has occurred.
MC9S08GB/GT Data Sheet, Rev. 2.3
58
Freescale Semiconductor
FLASH Registers and Control Bits
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.
1 = After a blank check command is completed and FCCF = 1, FBLANK = 1 indicates the FLASH
array is completely erased (all $FF).
0 = After a blank check command is completed and FCCF = 1, FBLANK = 0 indicates the FLASH
array is not completely erased.
4.6.6
FLASH Command Register (FCMD)
Only five command codes are recognized in normal user modes as shown in Table 4-9. Refer to
Section 4.4.3, “Program and Erase Command Execution” for a detailed discussion of FLASH
programming and erase operations.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
0
0
0
Write:
FCMD7
FCMD6
FCMD5
FCMD4
FCMD3
FCMD2
FCMD1
FCMD0
Reset:
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-9. FLASH Command Register (FCMD)
Table 4-9. FLASH Commands
Command
FCMD
Equate File Label
Blank check
$05
mBlank
Byte program
$20
mByteProg
Byte program — burst mode
$25
mBurstProg
Page erase (512 bytes/page)
$40
mPageErase
Mass erase (all FLASH)
$41
mMassErase
All other command codes are illegal and generate an access error.
It is not necessary to perform a blank check command after a mass erase operation. Only blank check is
required as part of the security unlocking mechanism.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
59
Chapter 4 Memory
MC9S08GB/GT Data Sheet, Rev. 2.3
60
Freescale Semiconductor
Chapter 5 Resets, Interrupts, and System Configuration
5.1
Introduction
This section discusses basic reset and interrupt mechanisms and the various sources of reset and interrupts
in the MC9S08GB/GT. Some interrupt sources from peripheral modules are discussed in greater detail
within other sections of this data manual. This section gathers basic information about all reset and
interrupt sources in one place for easy reference. A few reset and interrupt sources, including the computer
operating properly (COP) watchdog and real-time interrupt (RTI), are not part of on-chip peripheral
systems with their own sections but are part of the system control logic.
5.2
Features
Reset and interrupt features include:
• Multiple sources of reset for flexible system configuration and reliable operation:
— Power-on detection (POR)
— Low voltage detection (LVD) with enable
— External RESET pin with enable
— COP watchdog with enable and two timeout choices
— Illegal opcode
— Serial command from a background debug host
• Reset status register (SRS) to indicate source of most recent reset
• Separate interrupt vectors for each module (reduces polling overhead) (see Table 5-1)
5.3
MCU Reset
Resetting the MCU provides a way to start processing from a known set of initial conditions. During reset,
most control and status registers are forced to initial values and the program counter is loaded from the
reset vector ($FFFE:$FFFF). 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 $00FF at reset.
The MC9S08GB/GT has seven sources for reset:
• Power-on reset (POR)
• Low-voltage detect (LVD)
• Computer operating properly (COP) timer
• Illegal opcode detect
• Background debug forced reset
• The reset pin (RESET)
• Clock generator loss of lock and loss of clock reset
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
61
Chapter 5 Resets, Interrupts, and System Configuration
Each of these sources, with the exception of the background debug forced reset, has an associated bit in
the system reset status register. Whenever the MCU enters reset, the internal clock generator (ICG) module
switches to self-clocked mode with the frequency of fSelf_reset selected. The reset pin is driven low for 34
internal bus cycles where the internal bus frequency is half the ICG frequency. After the 34 cycles are
completed, the pin is released and will be pulled up by the internal pullup resistor, unless it is held low
externally. After the pin is released, it is sampled after another 38 cycles to determine whether the reset pin
is the cause of the MCU reset.
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 timer periodically. If the application program gets lost and fails to reset the COP before it
times out, a system reset is generated to force the system back to a known starting point. The COP
watchdog is enabled by the COPE bit in SOPT (see Section 5.8.4, “System Options Register (SOPT)” for
additional information). The COP timer 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 timer.
After any reset, the COP timer is enabled. This provides a reliable way to detect code that is not executing
as intended. If the COP watchdog is not used in an application, it can be disabled by clearing the COPE
bit in the write-once SOPT register. Also, the COPT bit can be used to choose one of two timeout periods
(218 or 213 cycles of the bus rate clock). Even if the application will use the reset default settings in COPE
and COPT, the user should still write to write-once SOPT during reset initialization to lock in the settings.
That way, they cannot be changed accidentally if the application program gets lost.
The write to SRS that services (clears) the COP timer should 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.
When the MCU is in active background mode, the COP timer is temporarily disabled.
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 set to 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
62
Freescale Semiconductor
Interrupts
When the CPU receives a qualified interrupt request, it completes the current instruction before responding
to the interrupt. The interrupt sequence follows 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.
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 just 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 5-1).
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
63
Chapter 5 Resets, Interrupts, and System Configuration
UNSTACKING
ORDER
TOWARD LOWER ADDRESSES
7
0
SP AFTER
INTERRUPT STACKING
5
1
CONDITION CODE REGISTER
4
2
3
3
ACCUMULATOR
* (LOW BYTE X)
INDEX REGISTER
2
4
PROGRAM COUNTER HIGH
1
5
PROGRAM COUNTER LOW
STACKING
ORDER
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 just 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 IRQSC status and control register. When the IRQ function is
enabled, synchronous logic monitors the pin for edge-only or edge-and-level events. When the MCU is in
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
Pin Configuration Options
The IRQ pin enable (IRQPE) control bit in the IRQSC register must be 1 for the IRQ pin to act as the
interrupt request (IRQ) input. When the pin is configured 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).
When the IRQ pin is configured to detect rising edges, an optional pulldown resistor is available rather than
a pullup resistor. 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
64
Freescale Semiconductor
Interrupts
NOTE
The voltage measured on the 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. All
other pins with enabled pullup resistors will have an unloaded measurement
of VDD.
5.5.2.2
Edge and Level Sensitivity
The IRQMOD control bit re-configures the detection logic so it detects edge events and pin levels. In this
edge 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 5-1 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
65
Chapter 5 Resets, Interrupts, and System Configuration
Table 5-1. Vector Summary
Vector
Priority
Lower
Higher
Vector
Number
26
through
31
Address
(High/Low)
$FFC0/FFC1
through
$FFCA/FFCB
25
$FFCC/FFCD
Vrti
24
$FFCE/FFCF
23
Vector Name
Module
Source
Enable
Description
Unused Vector Space
(available for user program)
RTIF
RTIE
Real-time interrupt
Viic1
System
control
IIC
IICIS
IICIE
$FFD0/FFD1
Vatd1
ATD
COCO
AIEN
22
$FFD2/FFD3
Vkeyboard1
KBI
21
$FFD4/FFD5
Vsci2tx
SCI2
20
$FFD6/FFD7
Vsci2rx
SCI2
19
$FFD8/FFD9
Vsci2err
SCI2
18
$FFDA/FFDB
Vsci1tx
SCI1
17
$FFDC/FFDD
Vsci1rx
SCI1
16
$FFDE/FFDF
Vsci1err
SCI1
15
$FFE0/FFE1
Vspi1
SPI
14
13
12
11
10
9
8
7
6
5
$FFE2/FFE3
$FFE4/FFE5
$FFE6/FFE7
$FFE8/FFE9
$FFEA/FFEB
$FFEC/FFED
$FFEE/FFEF
$FFF0/FFF1
$FFF2/FFF3
$FFF4/FFF5
Vtpm2ovf
Vtpm2ch4
Vtpm2ch3
Vtpm2ch2
Vtpm2ch1
Vtpm2ch0
Vtpm1ovf
Vtpm1ch2
Vtpm1ch1
Vtpm1ch0
TPM2
TPM2
TPM2
TPM2
TPM2
TPM2
TPM1
TPM1
TPM1
TPM1
KBIE
TIE
TCIE
ILIE
RIE
ORIE
NFIE
FEIE
PFIE
TIE
TCIE
ILIE
RIE
ORIE
NFIE
FEIE
PFIE
SPIE
SPIE
SPTIE
TOIE
CH4IE
CH3IE
CH2IE
CH1IE
CH0IE
TOIE
CH2IE
CH1IE
CH0IE
TPM2 overflow
TPM2 channel 4
TPM2 channel 3
TPM2 channel 2
TPM2 channel 1
TPM2 channel 0
TPM1 overflow
TPM1 channel 2
TPM1 channel 1
TPM1 channel 0
4
$FFF6/FFF7
Vicg
ICG
KBF
TDRE
TC
IDLE
RDRF
OR
NF
FE
PF
TDRE
TC
IDLE
RDRF
OR
NF
FE
PF
SPIF
MODF
SPTEF
TOF
CH4F
CH3F
CH2F
CH1F
CH0F
TOF
CH2F
CH1F
CH0F
ICGIF
(LOLS/LOCS)
IIC control
AD conversion
complete
Keyboard pins
LOLRE/LOCRE
ICG
3
$FFF8/FFF9
Vlvd
LVDF
LVDIE
Low-voltage detect
2
$FFFA/FFFB
Virq
System
control
IRQ
IRQIE
IRQ pin
1
$FFFC/FFFD
Vswi
Core
—
Software interrupt
Vreset
System
control
IRQF
SWI
Instruction
COP
LVD
RESET pin
Illegal opcode
COPE
LVDRE
—
—
Watchdog timer
Low-voltage detect
External pin
Illegal opcode
0
$FFFE/FFFF
SCI2 transmit
SCI2 receive
SCI2 error
SCI1 transmit
SCI1 receive
SCI1 error
SPI
MC9S08GB/GT Data Sheet, Rev. 2.3
66
Freescale Semiconductor
Low-Voltage Detect (LVD) System
5.6
Low-Voltage Detect (LVD) System
The MC9S08GB/GT includes a system to protect against low voltage conditions to protect memory
contents and control MCU system states during supply voltage variations. The system comprises 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 stop1 or 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.
5.7
Real-Time Interrupt (RTI)
The real-time interrupt function can be used to generate periodic interrupts based on a multiple of the
source clock's period. The RTI has two source clock choices, the external clock input (ICGERCLK) to the
ICG or the RTI's own internal clock. The RTI can be used in run, wait, stop2 and stop3 modes. It is not
available in stop1 mode.
In run and wait modes, only the external clock can be used as the RTI's clock source. In stop2 mode, only
the internal RTI clock can be used. In stop3, either the external clock or internal RTI clock can be used.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
67
Chapter 5 Resets, Interrupts, and System Configuration
When using the external oscillator in stop3 mode, it must be enabled in stop (OSCSTEN = 1) and
configured for low bandwidth operation (RANGE = 0).
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 select one of seven RTI periods. The RTI has a local interrupt enable,
RTIE, to allow masking of the real-time interrupt. The module can be disabled by writing 0:0:0 to
RTIS2:RTIS1:RTIS0 in which case the clock source input is disabled and no interrupts will be generated.
See Section 5.8.6, “System Real-Time Interrupt Status and Control Register (SRTISC),” for detailed
information about this register.
5.8
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.”
5.8.1
Interrupt Pin Request Status and Control Register (IRQSC)
This direct page register includes two unimplemented bits which always read 0, four read/write bits, one
read-only status bit, and one write-only bit. These bits are used to configure the IRQ function, report status,
and acknowledge IRQ events.
Read:
Bit 7
6
0
0
5
4
IRQEDG
IRQPE
3
2
IRQF
0
Write:
Reset:
1
Bit 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)
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, the optional pullup resistor is re-configured as an optional pulldown resistor.
1 = IRQ is rising edge or rising edge/high-level sensitive.
0 = IRQ is falling edge or falling edge/low-level sensitive.
MC9S08GB/GT Data Sheet, Rev. 2.3
68
Freescale Semiconductor
Reset, Interrupt, and System Control Registers and Control Bits
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. Also, when this bit is set, either an internal pull-up or an internal pull-down
resistor is enabled depending on the state of the IRQMOD bit.
1 = IRQ pin function is enabled.
0 = IRQ pin function is disabled.
IRQF — IRQ Flag
This read-only status bit indicates when an interrupt request event has occurred.
1 = IRQ event detected.
0 = No IRQ request.
IRQACK — 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.
IRQIE — IRQ Interrupt Enable
This read/write control bit determines whether IRQ events generate a hardware interrupt request.
1 = Hardware interrupt requested whenever IRQF = 1.
0 = Hardware interrupt requests from IRQF disabled (use polling).
IRQMOD — 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.
1 = IRQ event on falling edges and low levels or on rising edges and high levels.
0 = IRQ event on falling edges or rising edges only.
5.8.2
System Reset Status Register (SRS)
This register includes six 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
69
Chapter 5 Resets, Interrupts, and System Configuration
Read:
Bit 7
6
5
4
3
2
1
Bit 0
POR
PIN
COP
ILOP
0
ICG
LVD
0
Write:
Writing any value to SIMRS address clears COP watchdog timer.
Power-on reset:
1
0
0
0
0
0
1
0
Low-voltage reset:
U
0
0
0
0
0
1
0
Any other reset:
0
1
(1)
(1)
0
(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)
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 (LVD) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVD threshold.
1 = POR caused reset.
0 = Reset not caused by POR.
PIN — External Reset Pin
Reset was caused by an active-low level on the external reset pin.
1 = Reset came from external reset pin.
0 = Reset not caused by external reset pin.
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.
1 = Reset caused by COP timeout.
0 = Reset not caused by COP timeout.
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.
1 = Reset caused by an illegal opcode.
0 = Reset not caused by an illegal opcode.
ICG — Internal Clock Generation Module Reset
Reset was caused by an ICG module reset.
1 = Reset caused by ICG module.
0 = Reset not caused by ICG module.
MC9S08GB/GT Data Sheet, Rev. 2.3
70
Freescale Semiconductor
Reset, Interrupt, and System Control Registers and Control Bits
LVD — Low Voltage Detect
If the LVD reset is enabled (LVDE = LVDRE = 1) and the supply drops below the LVD trip voltage,
an LVD reset occurs. The LVD function is disabled when the MCU enters stop. To maintain LVD
operation in stop, the LVDSE bit must be set.
1 = Reset caused by LVD trip or POR.
0 = Reset not caused by LVD trip or POR.
5.8.3
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 $00.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
BDFR1
Write:
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)
BDFR — Background Debug Force Reset
A serial 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.
5.8.4
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.
Bit 7
6
5
COPE
COPT
STOPE
1
1
0
4
Read:
3
2
0
0
1
Bit 0
BKGDPE
Write:
Reset:
1
0
0
1
1
= Unimplemented or Reserved
Figure 5-5. System Options Register (SOPT)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
71
Chapter 5 Resets, Interrupts, and System Configuration
COPE — COP Watchdog Enable
This write-once bit defaults to 1 after reset.
1 = COP watchdog timer enabled (force reset on timeout).
0 = COP watchdog timer disabled.
COPT — COP Watchdog Timeout
This write-once bit defaults to 1 after reset.
1 = Long timeout period selected (218 cycles of BUSCLK).
0 = Short timeout period selected (213 cycles of BUSCLK).
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.
1 = Stop mode enabled.
0 = Stop mode disabled.
BKGDPE — Background Debug Mode Pin Enable
The BKGDPE bit enables the PTG0/BKGD/MS pin to function as BKGD/MS. When the bit is clear,
the pin will function as PTG0, which is an output-only general-purpose I/O. This pin always defaults
to BKGD/MS function after any reset.
1 = BKGD pin enabled.
0 = BKGD pin disabled.
5.8.5
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.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
REV3
REV2
REV1
REV0
ID11
ID10
ID9
ID8
Reset:
01
0(1)
0(1)
0(1)
0
0
0
0
Read:
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
Reset:
0
0
0
0
0
0
1
0
= Unimplemented or Reserved
1
The revision number that is hard coded into these bits reflects the current silicon revision level.
Figure 5-6. System Device Identification Register (SDIDH, SDIDL)
REV[3:0] — Revision Number
The high-order 4 bits of address $1806 are hard coded to reflect the current mask set revision number
(0–F).
MC9S08GB/GT Data Sheet, Rev. 2.3
72
Freescale Semiconductor
Reset, Interrupt, and System Control Registers and Control Bits
ID[11:0] — Part Identification Number
Each derivative in the HCS08 Family has a unique identification number. The MC9S08GB/GT is hard
coded to the value $002.
5.8.6
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.
Read:
Bit 7
6
RTIF
0
Write:
Reset:
5
4
RTICLKS
RTIE
0
0
3
2
1
Bit 0
RTIS2
RTIS1
RTIS0
0
0
0
0
RTIACK
0
0
0
= Unimplemented or Reserved
Figure 5-7. System RTI Status and Control Register (SRTISC)
RTIF — Real-Time Interrupt Flag
This read-only status bit indicates the periodic wakeup timer has timed out.
1 = Periodic wakeup timer timed out.
0 = Periodic wakeup timer not timed out.
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 0.
RTICLKS — Real-Time Interrupt Clock Select
This read/write bit selects the clock source for the real-time interrupt.
1 = Real-time interrupt request clock source is external clock.
0 = Real-time interrupt request clock source is internal oscillator.
RTIE — Real-Time Interrupt Enable
This read-write bit enables real-time interrupts.
1 = Real-time interrupts enabled.
0 = Real-time interrupts disabled.
RTIS2:RTIS1:RTIS0 — Real-Time Interrupt Period Selects
These read/write bits select the wakeup period for the RTI. The clock source for the real-time interrupt
is its own clock source, which oscillates with a period of approximately 1/fext, and it is independent of
other MCU clock sources. Using an external clock source, the delays will be crystal frequency divided
by value in RTIS2:RTIS1:RTIS0.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
73
Chapter 5 Resets, Interrupts, and System Configuration
Table 5-2. Real-Time Interrupt Period
1
2
RTIS2:RTIS1:RTIS0
Internal Clock Source 1
(tRTI = 1 ms, Nominal)
External Clock Source 2
Period = text
0:0:0
Disable periodic wakeup timer
Disable periodic wakeup timer
0:0:1
8 ms
text x 256
0:1:0
32 ms
tex x 1024
0:1:1
64 ms
tex x 2048
1:0:0
128 ms
tex x 4096
1:0:1
256 ms
text x 8192
1:1:0
512 ms
text x 16384
1:1:1
1.024 s
tex x 32768
See Table A-10 tRTI in Appendix A, “Electrical Characteristics” for the tolerance on these values.
text is based on the external clock source, resonator, or crystal selected by the ICG configuration. See Table A-9 for details.
5.8.7
System Power Management Status and Control 1 Register (SPMSC1)
Read:
Bit 7
6
LVDF
0
Write:
Reset:
5
4
3
2
LVDIE
LVDRE1
LVDSE(1)
LVDE(1)
0
1
1
1
1
Bit 0
0
0
0
0
LVDACK
0
0
= Unimplemented or Reserved
1
This bit can be written only one time after reset. Additional writes are ignored.
Figure 5-8. System Power Management Status and Control 1 Register (SPMSC1)
LVDF — Low-Voltage Detect Flag
Provided LVDE = 1, this read-only status bit indicates a low-voltage detect event.
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.
LVDIE — Low-Voltage Detect Interrupt Enable
This read/write bit enables hardware interrupt requests for LVDF.
1 = Request a hardware interrupt when LVDF = 1.
0 = Hardware interrupt disabled (use polling).
MC9S08GB/GT Data Sheet, Rev. 2.3
74
Freescale Semiconductor
Reset, Interrupt, and System Control Registers and Control Bits
LVDRE — Low-Voltage Detect Reset Enable
This read/write bit enables LVDF events to generate a hardware reset (provided LVDE = 1).
1 = Force an MCU reset when LVDF = 1.
0 = LVDF does not generate hardware resets.
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.
1 = Low-voltage detect enabled during stop mode.
0 = Low-voltage detect disabled during stop mode.
LVDE — Low-Voltage Detect Enable
This read/write bit enables low-voltage detect logic and qualifies the operation of other bits in this
register.
1 = LVD logic enabled.
0 = LVD logic disabled.
5.8.8
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.
Read:
Bit 7
6
LVWF
0
Write:
5
4
LVDV
LVWV
3
2
PPDF
0
LVWACK
Bit 0
PDC
PPDC
PPDACK
Power-on reset:
01
0
0
0
0
0
0
0
LVD reset:
0(1)
0
U
U
0
0
0
0
Any other reset:
0(1)
0
U
U
0
0
0
0
= Unimplemented or Reserved
1
1
U = Unaffected by reset
LVWF will be set in the case when VSupply transitions below the trip point or after reset and VSupply is already below
VLVW.
Figure 5-9. System Power Management Status and Control 2 Register (SPMSC2)
LVWF — Low-Voltage Warning Flag
The LVWF bit indicates the low-voltage warning status.
1 = Low voltage warning is present or was present.
0 = Low voltage warning not present.
LVWACK — Low-Voltage Warning Acknowledge
The LVWACK bit indicates the low-voltage warning acknowledge.
Writing a 1 to LVWACK clears LVWF to 0 if a low voltage warning is not present.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
75
Chapter 5 Resets, Interrupts, and System Configuration
LVDV — Low-Voltage Detect Voltage Select
The LVDV bit selects the LVD trip point voltage (VLVD).
1 = High trip point selected (VLVD = VLVDH).
0 = Low trip point selected (VLVD = VLVDL).
LVWV — Low-Voltage Warning Voltage Select
The LVWV bit selects the LVW trip point voltage (VLVW).
1 = High trip point selected (VLVW = VLVWH).
0 = Low trip point selected (VLVW = VLVWL).
PPDF — Partial Power Down Flag
The PPDF bit indicates that the MCU has exited the stop2 mode.
1 = Stop2 mode recovery.
0 = Not stop2 mode recovery.
PPDACK — Partial Power Down Acknowledge
Writing a 1 to PPDACK clears the PPDF bit.
PDC — Power Down Control
The write-once PDC bit controls entry into the power down (stop2 and stop1) modes.
1 = Power down modes are enabled.
0 = Power down modes are disabled.
PPDC — Partial Power Down Control
The write-once PPDC bit controls which power down mode, stop1 or stop2, is selected.
1 = Stop2, partial power down, mode enabled if PDC set.
0 = Stop1, full power down, mode enabled if PDC set.
MC9S08GB/GT Data Sheet, Rev. 2.3
76
Freescale Semiconductor
Chapter 6 Parallel Input/Output
6.1
Introduction
This section explains software controls related to parallel input/output (I/O). The MC9S08GBxx has seven
I/O ports which include a total of 56 general-purpose I/O pins (one of these pins is output only). The
MC9S08GTxx has six I/O ports which include a total of up to 39 general-purpose I/O pins, depending on
the package (one pin, PTG0, is output only). 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, external interrupts, or
keyboard interrupts. When these other modules are not controlling the port pins, they revert to
general-purpose I/O control. For each I/O pin, a port data bit provides access to input (read) and output
(write) data, a data direction bit controls the direction of the pin, and a pullup enable bit enables an internal
pullup device (provided the pin is configured as an input), and a slew rate control bit controls the rise and
fall times of the pins.
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
77
Chapter 6 Parallel Input/Output
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown
available when KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 6-1. Block Diagram Highlighting Parallel Input/Output Pins
MC9S08GB/GT Data Sheet, Rev. 2.3
78
Freescale Semiconductor
Features
6.2
Features
Parallel I/O features, depending on package choice, include:
• A total of 56 general-purpose I/O pins in seven ports (PTG0 is output only)
• High-current drivers on port C and port F pins
• Hysteresis input buffers
• Software-controlled pullups on each input pin
• Software-controlled slew rate output buffers
• Eight port A pins shared with KBI1
• Eight port B pins shared with ATD1
• Eight high-current port C pins shared with SCI2 and IIC1
• Eight port D pins shared with TPM1 and TPM2
• Eight port E pins shared with SCI1 and SPI1
• Eight high-current port F pins
• Eight port G pins shared with EXTAL, XTAL, and BKGD/MS
6.3
Pin Descriptions
The MC9S08GB/GT has a total of 56 parallel I/O pins (one is output only) in seven 8-bit 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, BKGD/MS is enabled and therefore is not usable as an output pin until BKGDPE in SOPT is
cleared. The rest of the peripheral functions are disabled. After reset, all data direction and pullup enable
controls are set to 0s. These pins default to being high-impedance inputs with on-chip pullup devices
disabled.
The following paragraphs discuss each port and the software controls that determine each pin’s use.
6.3.1
Port A and Keyboard Interrupts
Port A
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTA7/
KBI1P7
PTA6/
KBI1P6
PTA5/
KBI1P5
PTA4/
KBI1P4
PTA3/
KBI1P3
PTA2/
KBI1P2
PTA1/
KBI1P1
PTA0/
KBI1P0
Figure 6-2. Port A Pin Names
Port A is an 8-bit port shared among the KBI keyboard interrupt inputs and general-purpose I/O. Any pins
enabled as KBI inputs will be forced to act as inputs.
Port A pins are available as general-purpose I/O pins controlled by the port A data (PTAD), data direction
(PTADD), pullup enable (PTAPE), and slew rate control (PTASE) registers. Refer to Section 6.4, “Parallel
I/O Controls,” for more information about general-purpose I/O control.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
79
Chapter 6 Parallel Input/Output
Port A can be configured to be keyboard interrupt input pins. Refer to Chapter 9, “Keyboard Interrupt
(KBI) Module,” for more information about using port A pins as keyboard interrupts pins.
6.3.2
Port B and Analog to Digital Converter Inputs
Port B
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTB7/
AD1P7
PTB6/
AD1P6
PTB5/
AD1P5
PTB4/
AD1P4
PTB3/
AD1P3
PTB2/
AD1P2
PTB1/
AD1P1
PTB0/
AD1P0
Figure 6-3. Port B Pin Names
Port B is an 8-bit port shared among the ATD inputs and general-purpose I/O. Any pin enabled as an ATD
input will be forced to act as an input.
Port B pins are available as general-purpose I/O pins controlled by the port B data (PTBD), data direction
(PTBDD), pullup enable (PTBPE), and slew rate control (PTBSE) registers. Refer to Section 6.4, “Parallel
I/O Controls,” for more information about general-purpose I/O control.
When the ATD module is enabled, analog pin enables are used to specify which pins on port B will be used
as ATD inputs. Refer to Chapter 14, “Analog-to-Digital Converter (ATD) Module,” for more information
about using port B pins as ATD pins.
6.3.3
Port C and SCI2, IIC, and High-Current Drivers
Port C
MCU Pin:
Bit 7
6
5
3
3
2
1
Bit 0
PTC7
PTC6
PTC5
PTC4
PTC3/
SCL1
PTC2/
SDA1
PTC1/
RxD2
PTC0/
TxD2
Figure 6-4. Port C Pin Names
Port C is an 8-bit port which is shared among the SCI2 and IIC1 modules, and general-purpose I/O. When
SCI2 or IIC1 modules are enabled, the pin direction will be controlled by the module or function. Port C
has high current output drivers.
Port C pins are available as general-purpose I/O pins controlled by the port C data (PTCD), data direction
(PTCDD), pullup enable (PTCPE), and slew rate control (PTCSE) registers. Refer to Section 6.4, “Parallel
I/O Controls,” for more information about general-purpose I/O control.
When the SCI2 module is enabled, PTC0 serves as the SCI2 module’s transmit pin (TxD2) and PTC1
serves as the receive pin (RxD2). Refer to Chapter 11, “Serial Communications Interface (SCI) Module,”
for more information about using PTC0 and PTC1 as SCI pins
When the IIC module is enabled, PTC2 serves as the IIC modules’s serial data input/output pin (SDA1)
and PTC3 serves as the clock pin (SCL1). Refer to Chapter 13, “Inter-Integrated Circuit (IIC) Module,”
for more information about using PTC2 and PTC3 as IIC pins.
MC9S08GB/GT Data Sheet, Rev. 2.3
80
Freescale Semiconductor
Pin Descriptions
6.3.4
Port D, TPM1 and TPM2
Port D
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTD7/
PTD6/
PTD5/
PTD4/
PTD3/
PTD2/
PTD1/
PTD0/
TPM2CH4 TPM2CH3 TPM2CH2 TPM2CH1 TPM2CH0 TPM1CH2 TPM1CH1 TPM1CH0
Figure 6-5. Port D Pin Names
Port D is an 8-bit port shared with the two TPM modules, TPM1 and TPM2, and general-purpose I/O.
When the TPM1 or TPM2 modules are enabled in output compare or input capture modes of operation,
the pin direction will be controlled by the module function.
Port D pins are available as general-purpose I/O pins controlled by the port D data (PTDD), data direction
(PTDDD), pullup enable (PTDPE), and slew rate control (PTDSE) registers. Refer to Section 6.4, “Parallel
I/O Controls” for more information about general-purpose I/O control.
The TPM2 module can be configured to use PTD7–PTD3 as either input capture, output compare, PWM,
or external clock input pins (PTD3 only). Refer to Chapter 10, “Timer/PWM (TPM) Module” for more
information about using PTD7–PTD3 as timer pins.
The TPM1 module can be configured to use PTD2–PTD0 as either input capture, output compare, PWM,
or external clock input pins (PTD0 only). Refer to Chapter 10, “Timer/PWM (TPM) Module” for more
information about using PTD2–PTD0 as timer pins.
6.3.5
Port E, SCI1, and SPI
Port E
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTE7
PTE6
PTE5/
SPSCK1
PTE4/
MOSI1
PTE3/
MISO1
PTE2/
SS1
PTE1/
RxD1
PTE0/
TxD1
Figure 6-6. Port E Pin Names
Port E is an 8-bit port shared with the SCI1 module, SPI1 module, and general-purpose I/O. When the SCI
or SPI modules are enabled, the pin direction will be controlled by the module function.
Port E pins are available as general-purpose I/O pins controlled by the port E data (PTED), data direction
(PTEDD), pullup enable (PTEPE), and slew rate control (PTESE) registers. Refer to Section 6.4, “Parallel
I/O Controls” for more information about general-purpose I/O control.
When the SCI1 module is enabled, PTE0 serves as the SCI1 module’s transmit pin (TxD1) and PTE1
serves as the receive pin (RxD1). Refer to Chapter 11, “Serial Communications Interface (SCI) Module”
for more information about using PTE0 and PTE1 as SCI pins.
When the SPI module is enabled, PTE2 serves as the SPI module’s slave select pin (SS1), PTE3 serves as
the master-in slave-out pin (MISO1), PTE4 serves as the master-out slave-in pin (MOSI1), and PTE5
serves as the SPI clock pin (SPSCK1). Refer to Chapter 12, “Serial Peripheral Interface (SPI) Module for
more information about using PTE5–PTE2 as SPI pins.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
81
Chapter 6 Parallel Input/Output
6.3.6
Port F and High-Current Drivers
Port F
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTF7
PTF6
PTF5
PTF4
PTF3
PTF2
PTF1
PTF0
Figure 6-7. Port F Pin Names
Port F is an 8-bit port general-purpose I/O that is not shared with any peripheral module. Port F has high
current output drivers.
Port F pins are available as general-purpose I/O pins controlled by the port F data (PTFD), data direction
(PTFDD), pullup enable (PTFPE), and slew rate control (PTFSE) registers. Refer to Section 6.4, “Parallel
I/O Controls” for more information about general-purpose I/O control.
6.3.7
Port G, BKGD/MS, and Oscillator
Port G
MCU Pin:
Bit 7
6
5
4
3
2
1
Bit 0
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/
EXTAL
PTG1/
XTAL
PTG0/
BKGD/MS
Figure 6-8. Port G Pin Names
Port G is an 8-bit port which is shared among the background/mode select function, oscillator, and
general-purpose I/O. When the background/mode select function or oscillator is enabled, the pin direction
will be controlled by the module function.
Port G pins are available as general-purpose I/O pins controlled by the port G data (PTGD), data direction
(PTGDD), pullup enable (PTGPE), and slew rate control (PTGSE) registers. Refer to Section 6.4, “Parallel
I/O Controls” for more information about general-purpose I/O control.
The internal pullup for PTG0 is enabled when the background/mode select function is enabled, regardless
of the state of PTGPE0. During reset, the BKGD/MS pin functions as a mode select pin. After the MCU
is out of reset, the BKGD/MS pin becomes the background communications input/output pin. The PTG0
can be configured to be a general-purpose output pin. Refer to Chapter 3, “Modes of Operation”,
Chapter 5, “Resets, Interrupts, and System Configuration”, and Chapter 15, “Development Support” for
more information about using this pin.
The ICG module can be configured to use PTG2–PTG1 ports as crystal oscillator or external clock pins.
Refer to Chapter 13, “Inter-Integrated Circuit (IIC) Module” for more information about using these pins
as oscillator pins.
6.4
Parallel I/O Controls
Provided no on-chip peripheral is controlling a port pin, the pins operate as general-purpose I/O pins that
are accessed and controlled by a data register (PTxD), a data direction register (PTxDD), a pullup enable
register (PTxPE), and a slew rate control register (PTxSE) where x is A, B, C, D, E, F, or G.
MC9S08GB/GT Data Sheet, Rev. 2.3
82
Freescale Semiconductor
Parallel I/O Controls
Reads of the data register return the pin value (if PTxDDn = 0) or the contents of the port data register (if
PTxDDn = 1). Writes to the port data register are latched into the port register whether the pin is controlled
by an on-chip peripheral or the pin is configured as an input. If the corresponding pin is not controlled by
a peripheral and is configured as an output, this level will be driven out the port pin.
6.4.1
Data Direction Control
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 control 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 control 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.
For the MC9S08GB/GT MCU, reads of PTG0/BKGD/MS will return the value on the output 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.
6.4.2
Internal Pullup Control
An internal pullup device can be enabled for each port pin that is configured as an input (PTxDDn = 0).
The pullup device is available for a peripheral module to use, provided the peripheral is enabled and is an
input function as long as the PTxDDn = 0.
For the four configurable KBI module inputs on PTA7–PTA4, when a pin is configured to detect rising
edges, the port pullup enable associated with the pin (PTAPEn) selects a pulldown rather than a pullup
device.
6.4.3
Slew Rate Control
Slew rate control can be enabled for each port pin that is configured as an output (PTxDDn = 1) or if a
peripheral module is enabled and its function is an output. Not all peripheral modules’ outputs have slew
rate control; refer to Chapter 2, “Pins and Connections” for more information about which pins have slew
rate control.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
83
Chapter 6 Parallel Input/Output
6.5
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:
• When the MCU enters stop1 mode, all internal registers including general-purpose I/O control and
data registers are powered down. All of the general-purpose I/O pins assume their reset state:
output buffers and pullups turned off. Upon exit from stop1, all I/O must be initialized as if the
MCU had been reset.
• When the MCU enters stop2 mode, the internal registers are powered down as in stop1 but the I/O
pin states are latched and held. For example, a port pin that is an output driving low continues to
function as an output driving low even though its associated data direction and output data registers
are powered down internally. Upon exit from stop2, the pins continue to hold their states until a 1
is written to the PPDACK bit. To avoid discontinuity in the pin state following exit from stop2, the
user must restore the port control and data registers to the values they held before entering stop2.
These values can be stored in RAM before entering stop2 because the RAM is maintained during
stop2.
• 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.
6.6
Parallel I/O Registers and Control Bits
This section provides information about all registers and control bits associated with the parallel I/O ports.
Refer to tables in Chapter 4, “Memory” for the absolute address assignments for all parallel I/O 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.
6.6.1
Port A Registers (PTAD, PTAPE, PTASE, and PTADD)
Port A includes eight pins shared between general-purpose I/O and the KBI module. Port A pins used as
general-purpose I/O pins are controlled by the port A data (PTAD), data direction (PTADD), pullup enable
(PTAPE), and slew rate control (PTASE) registers.
If the KBI takes control of a port A pin, the corresponding PTASE bit is ignored since the pin functions as
an input. As long as PTADD is 0, the PTAPE controls the pullup enable for the KBI function. Reads of
PTAD will return the logic value of the corresponding pin, provided PTADD is 0.
MC9S08GB/GT Data Sheet, Rev. 2.3
84
Freescale Semiconductor
Parallel I/O Registers and Control Bits
PTAD
Bit 7
6
5
4
3
2
1
Bit 0
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
0
0
0
0
0
0
0
0
PTAPE7
PTAPE6
PTAPE5
PTAPE4
PTAPE3
PTAPE2
PTAPE1
PTAPE0
0
0
0
0
0
0
0
0
PTASE7
PTASE6
PTASE5
PTASE4
PTASE3
PTASE2
PTASE1
PTASE0
0
0
0
0
0
0
0
0
PTADD7
PTADD6
PTADD5
PTADD4
PTADD3
PTADD2
PTADD1
PTADD0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
PTAPE
Read:
Write:
Reset:
PTASE
Read:
Write:
Reset:
PTADD
Read:
Write:
Reset:
Figure 6-9. Port A Registers
PTADn — Port A Data Register Bit n (n = 0–7)
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.
PTAPEn — Pullup Enable for Port A Bit n (n = 0–7)
For port A pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled provided the corresponding PTADDn is 0. For port A pins that are configured as outputs,
these bits are ignored and the internal pullup devices are disabled. When any of bits 7 through 4 of port
A are enabled as KBI inputs and are configured to detect rising edges/high levels, the pullup enable
bits enable pulldown rather than pullup devices.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
85
Chapter 6 Parallel Input/Output
PTASEn — Slew Rate Control Enable for Port A Bit n (n = 0–7)
For port A pins that are outputs, these read/write control bits determine whether the slew rate
controlled outputs are enabled. For port A pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
PTADDn — Data Direction for Port A Bit n (n = 0–7)
These read/write bits control the direction of port A pins and what is read for PTAD reads.
1 = Output driver enabled for port A bit n and PTAD reads return the contents of PTADn.
0 = Input (output driver disabled) and reads return the pin value.
6.6.2
Port B Registers (PTBD, PTBPE, PTBSE, and PTBDD)
Port B includes eight general-purpose I/O pins that share with the ATD function. Port B pins used as
general-purpose I/O pins are controlled by the port B data (PTBD), data direction (PTBDD), pullup enable
(PTBPE), and slew rate control (PTBSE) registers.
If the ATD takes control of a port B pin, the corresponding PTBDD, PTBSE, and PTBPE bits are ignored.
When a port B pin is being used as an ATD pin, reads of PTBD will return a 0 of the corresponding pin,
provided PTBDD is 0.
PTBD
Bit 7
6
5
4
3
2
1
Bit 0
PTBD7
PTBD6
PTBD5
PTBD4
PTBD3
PTBD2
PTBD1
PTBD0
0
0
0
0
0
0
0
0
PTBPE7
PTBPE6
PTBPE5
PTBPE4
PTBPE3
PTBPE2
PTBPE1
PTBPE0
0
0
0
0
0
0
0
0
PTBSE7
PTBSE6
PTBSE5
PTBSE4
PTBSE3
PTBSE2
PTBSE1
PTBSE0
0
0
0
0
0
0
0
0
PTBDD7
PTBDD6
PTBDD5
PTBDD4
PTBDD3
PTBDD2
PTBDD1
PTBDD0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
PTBPE
Read:
Write:
Reset:
PTBSE
Read:
Write:
Reset:
PTBDD
Read:
Write:
Reset:
Figure 6-10. Port B Registers
MC9S08GB/GT Data Sheet, Rev. 2.3
86
Freescale Semiconductor
Parallel I/O Registers and Control Bits
PTBDn — Port B Data Register Bit n (n = 0–7)
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 on the corresponding pins because reset
also configures all port pins as high-impedance inputs with pullups disabled.
PTBPEn — Pullup Enable for Port B Bit n (n = 0–7)
For port B pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled. For port B pins that are configured as outputs, these bits are ignored and the internal pullup
devices are disabled.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
PTBSEn — Slew Rate Control Enable for Port B Bit n (n = 0–7)
For port B pins that are outputs, these read/write control bits determine whether the slew rate controlled
outputs are enabled. For port B pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
PTBDDn — Data Direction for Port B Bit n (n = 0–7)
These read/write bits control the direction of port B pins and what is read for PTBD reads.
1 = Output driver enabled for port B bit n and PTBD reads return the contents of PTBDn.
0 = Input (output driver disabled) and reads return the pin value.
6.6.3
Port C Registers (PTCD, PTCPE, PTCSE, and PTCDD)
Port C includes eight general-purpose I/O pins that share with the SCI2 and IIC modules. Port C pins used
as general-purpose I/O pins are controlled by the port C data (PTCD), data direction (PTCDD), pullup
enable (PTCPE), and slew rate control (PTCSE) registers.
If the SCI2 takes control of a port C pin, the corresponding PTCDD bit is ignored. PTCSE can be used to
provide slew rate on the SCI2 transmit pin, TxD2. PTCPE can be used, provided the corresponding
PTCDD bit is 0, to provide a pullup device on the SCI2 receive pin, RxD2.
If the IIC takes control of a port C pin, the corresponding PTCDD bit is ignored. PTCSE can be used to
provide slew rate on the IIC serial data pin (SDA1), when in output mode and the IIC clock pin (SCL1).
PTCPE can be used, provided the corresponding PTCDD bit is 0, to provide a pullup device on the IIC
serial data pin, when in receive mode.
Reads of PTCD will return the logic value of the corresponding pin, provided PTCDD is 0.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
87
Chapter 6 Parallel Input/Output
PTCD
Bit 7
6
5
4
3
2
1
Bit 0
PTCD7
PTCD6
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
0
0
0
0
0
0
0
0
PTCPE7
PTCPE6
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
0
0
0
0
0
0
0
0
PTCSE7
PTCSE6
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
0
0
0
0
0
0
0
0
PTCDD7
PTCDD6
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
PTCPE
Read:
Write:
Reset:
PTCSE
Read:
Write:
Reset:
PTCDD
Read:
Write:
Reset:
Figure 6-11. Port C Registers
PTCDn — Port C Data Register Bit n (n = 0–7)
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.
PTCPEn — Pullup Enable for Port C Bit n (n = 0–7)
For port C pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled. For port C pins that are configured as outputs, these bits are ignored and the internal pullup
devices are disabled.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
PTCSEn — Slew Rate Control Enable for Port C Bit n (n = 0–7)
For port C pins that are outputs, these read/write control bits determine whether the slew rate controlled
outputs are enabled. For port B pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
88
Freescale Semiconductor
Parallel I/O Registers and Control Bits
PTCDDn — Data Direction for Port C Bit n (n = 0–7)
These read/write bits control the direction of port C pins and what is read for PTCD reads.
1 = Output driver enabled for port C bit n and PTCD reads return the contents of PTCDn.
0 = Input (output driver disabled) and reads return the pin value.
6.6.4
Port D Registers (PTDD, PTDPE, PTDSE, and PTDDD)
Port D includes eight pins shared between general-purpose I/O, TPM1, and TPM2. Port D pins used as
general-purpose I/O pins are controlled by the port D data (PTDD), data direction (PTDDD), pullup enable
(PTDPE), and slew rate control (PTDSE) registers.
If a TPM takes control of a port D pin, the corresponding PTDDD bit is ignored. When the TPM is in
output compare mode, the corresponding PTDSE can be used to provide slew rate on the pin. When the
TPM is in input capture mode, the corresponding PTDPE can be used, provided the corresponding
PTDDD bit is 0, to provide a pullup device on the pin.
Reads of PTDD will return the logic value of the corresponding pin, provided PTDDD is 0.
PTDD
Bit 7
6
5
4
3
2
1
Bit 0
PTDD7
PTDD6
PTDD5
PTDD4
PTDD3
PTDD2
PTDD1
PTDD0
0
0
0
0
0
0
0
0
PTDPE7
PTDPE6
PTDPE5
PTDPE4
PTDPE3
PTDPE2
PTDPE1
PTDPE0
0
0
0
0
0
0
0
0
PTDSE7
PTDSE6
PTDSE5
PTDSE4
PTDSE3
PTDSE2
PTDSE1
PTDSE0
0
0
0
0
0
0
0
0
PTDDD7
PTDDD6
PTDDD5
PTDDD4
PTDDD3
PTDDD2
PTDDD1
PTDDD0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
PTDPE
Read:
Write:
Reset:
PTDSE
Read:
Write:
Reset:
PTDDD
Read:
Write:
Reset:
Figure 6-12. Port D Registers
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
89
Chapter 6 Parallel Input/Output
PTDDn — Port D Data Register Bit n (n = 0–7)
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.
PTDPEn — Pullup Enable for Port D Bit n (n = 0–7)
For port D pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled. For port D pins that are configured as outputs, these bits are ignored and the internal pullup
devices are disabled.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
PTDSEn — Slew Rate Control Enable for Port D Bit n (n = 0–7)
For port D pins that are outputs, these read/write control bits determine whether the slew rate
controlled outputs are enabled. For port D pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
PTDDDn — Data Direction for Port D Bit n (n = 0–7)
These read/write bits control the direction of port D pins and what is read for PTDD reads.
1 = Output driver enabled for port D bit n and PTDD reads return the contents of PTDDn.
0 = Input (output driver disabled) and reads return the pin value.
6.6.5
Port E Registers (PTED, PTEPE, PTESE, and PTEDD)
Port E includes eight general-purpose I/O pins that share with the SCI1 and SPI modules. Port E pins used
as general-purpose I/O pins are controlled by the port E data (PTED), data direction (PTEDD), pullup
enable (PTEPE), and slew rate control (PTESE) registers.
If the SCI1 takes control of a port E pin, the corresponding PTEDD bit is ignored. PTESE can be used to
provide slew rate on the SCI1 transmit pin, TxD1. PTEPE can be used, provided the corresponding
PTEDD bit is 0, to provide a pullup device on the SCI1 receive pin, RxD1.
If the SPI takes control of a port E pin, the corresponding PTEDD bit is ignored. PTESE can be used to
provide slew rate on the SPI serial output pin (MOSI1 or MISO1) and serial clock pin (SPSCK1)
depending on the SPI operational mode. PTEPE can be used, provided the corresponding PTEDD bit is 0,
to provide a pullup device on the SPI serial input pins (MOSI1 or MISO1) and slave select pin (SS1)
depending on the SPI operational mode.
Reads of PTED will return the logic value of the corresponding pin, provided PTEDD is 0.
MC9S08GB/GT Data Sheet, Rev. 2.3
90
Freescale Semiconductor
Parallel I/O Registers and Control Bits
PTED
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
PTED7
PTED6
PTED5
PTED4
PTED3
PTED2
PTED1
PTED0
0
0
0
0
0
0
0
0
PTEPE7
PTEPE6
PTEPE5
PTEPE4
PTEPE3
PTEPE2
PTEPE1
PTEPE0
0
0
0
0
0
0
0
0
PTESE7
PTESE6
PTESE5
PTESE4
PTESE3
PTESE2
PTESE1
PTESE0
0
0
0
0
0
0
0
0
PTEDD7
PTEDD6
PTEDD5
PTEDD4
PTEDD3
PTEDD2
PTEDD1
PTEDD0
0
0
0
0
0
0
0
0
PTEPE
Read:
Write:
Reset:
PTESE
Read:
Write:
Reset:
PTEDD
Read:
Write:
Reset:
Figure 6-13. Port E Registers
PTEDn — Port E Data Register Bit n (n = 0–7)
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 in 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.
PTEPEn — Pullup Enable for Port E Bit n (n = 0–7)
For port E pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled. For port E pins that are configured as outputs, these bits are ignored and the internal pullup
devices are disabled.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
PTESEn — Slew Rate Control Enable for Port E Bit n (n = 0–7)
For port E pins that are outputs, these read/write control bits determine whether the slew rate controlled
outputs are enabled. For port E pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
91
Chapter 6 Parallel Input/Output
PTEDDn — Data Direction for Port E Bit n (n = 0–7)
These read/write bits control the direction of port E pins and what is read for PTED reads.
1 = Output driver enabled for port E bit n and PTED reads return the contents of PTEDn.
0 = Input (output driver disabled) and reads return the pin value.
6.6.6
Port F Registers (PTFD, PTFPE, PTFSE, and PTFDD)
Port F includes eight general-purpose I/O pins that are not shared with any peripheral module. Port F pins
used as general-purpose I/O pins are controlled by the port F data (PTFD), data direction (PTFDD), pullup
enable (PTFPE), and slew rate control (PTFSE) registers.
PTFD
Bit 7
6
5
4
3
2
1
Bit 0
PTFD7
PTFD6
PTFD5
PTFD4
PTFD3
PTFD2
PTFD1
PTFD0
0
0
0
0
0
0
0
0
PTFPE7
PTFPE6
PTFPE5
PTFPE4
PTFPE3
PTFPE2
PTFPE1
PTFPE0
0
0
0
0
0
0
0
0
PTFSE7
PTFSE6
PTFSE5
PTFSE4
PTFSE3
PTFSE2
PTFSE1
PTFSE0
0
0
0
0
0
0
0
0
PTFDD7
PTFDD6
PTFDD5
PTFDD4
PTFDD3
PTFDD2
PTFDD1
PTFDD0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
PTFPE
Read:
Write:
Reset:
PTFSE
Read:
Write:
Reset:
PTFDD
Read:
Write:
Reset:
Figure 6-14. Port F Registers
PTFDn — Port PTF Data Register Bit n (n = 0–7)
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
92
Freescale Semiconductor
Parallel I/O Registers and Control Bits
PTFPEn — Pullup Enable for Port F Bit n (n = 0–7)
For port F pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled. For port F pins that are configured as outputs, these bits are ignored and the internal pullup
devices are disabled.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
PTFSEn — Slew Rate Control Enable for Port F Bit n (n = 0–7)
For port F pins that are outputs, these read/write control bits determine whether the slew rate controlled
outputs are enabled. For port F pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
PTFDDn — Data Direction for Port F Bit n (n = 0–7)
These read/write bits control the direction of port F pins and what is read for PTFD reads.
1 = Output driver enabled for port F bit n and PTFD reads return the contents of PTFDn.
0 = Input (output driver disabled) and reads return the pin value.
6.6.7
Port G Registers (PTGD, PTGPE, PTGSE, and PTGDD)
Port G includes eight general-purpose I/O pins that are shared with BKGD/MS function and the oscillator
or external clock pins. Port G pins used as general-purpose I/O pins are controlled by the port G data
(PTGD), data direction (PTGDD), pullup enable (PTGPE), and slew rate control (PTGSE) registers.
Port pin PTG0, while in reset, defaults to the BKGD/MS pin. After the MCU is out of reset, PTG0 can be
configured to be a general-purpose output pin. When BKGD/MS takes control of PTG0, the corresponding
PTGDD, PTGPE, and PTGPSE bits are ignored.
Port pins PTG1 and PTG2 can be configured to be oscillator or external clock pins. When the oscillator
takes control of a port G pin, the corresponding PTGD, PTGDD, PTGSE, and PTGPE bits are ignored.
Reads of PTGD will return the logic value of the corresponding pin, provided PTGDD is 0.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
93
Chapter 6 Parallel Input/Output
PTGD
Bit 7
6
5
4
3
2
1
Bit 0
PTGD7
PTGD6
PTGD5
PTGD4
PTGD3
PTGD2
PTGD1
PTGD0
0
0
0
0
0
0
0
0
PTGPE7
PTGPE6
PTGPE5
PTGPE4
PTGPE3
PTGPE2
PTGPE1
PTGPE0
0
0
0
0
0
0
0
0
PTGSE7
PTGSE6
PTGSE5
PTGSE4
PTGSE3
PTGSE2
PTGSE1
PTGSE0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
PTGPE
Read:
Write:
Reset:
PTGSE
Read:
Write:
Reset:
PTGDD
Read:
PTGDD7 PTGDD6 PTGDD5 PTGDD4 PTGDD3 PTGDD2 PTGDD1 PTGDD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 6-15. Port G Registers
PTGDn — Port PTG Data Register Bit n (n = 0–7)
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.
PTGPEn — Pullup Enable for Port G Bit n (n = 0–7)
For port G pins that are inputs, these read/write control bits determine whether internal pullup devices
are enabled. For port G pins that are configured as outputs, these bits are ignored and the internal pullup
devices are disabled.
1 = Internal pullup device enabled.
0 = Internal pullup device disabled.
PTGSEn — Slew Rate Control Enable for Port G Bit n (n = 0–7)
For port G pins that are outputs, these read/write control bits determine whether the slew rate
controlled outputs are enabled. For port G pins that are configured as inputs, these bits are ignored.
1 = Slew rate control enabled.
0 = Slew rate control disabled.
MC9S08GB/GT Data Sheet, Rev. 2.3
94
Freescale Semiconductor
Parallel I/O Registers and Control Bits
PTGDDn — Data Direction for Port G Bit n (n = 0–7)
These read/write bits control the direction of port G pins and what is read for PTGD reads.
1 = Output driver enabled for port G bit n and PTGD reads return the contents of PTGDn.
0 = Input (output driver disabled) and reads return the pin value.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
95
Chapter 6 Parallel Input/Output
MC9S08GB/GT Data Sheet, Rev. 2.3
96
Freescale Semiconductor
Chapter 7 Internal Clock Generator (ICG) Module
The MC9S08GB/GT microcontroller provides one internal clock generation (ICG) module to create the
system bus frequency. All functions described in this section are available on the MC9S08GB/GT
microcontroller. The EXTAL and XTAL pins share port G bits 2 and 1, respectively. 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.”
ICGERCLK
SYSTEM
CONTROL
LOGIC
TPM1
TPM2
IIC1
SCI1
SCI2
SPI1
RTI
FFE
÷2
ICG
FIXED FREQ CLOCK (XCLK)
ICGOUT
÷2
BUSCLK
ICGLCLK*
CPU
BDC
* ICGLCLK is the alternate BDC clock source for the MC9S08GB/GT.
ATD1
RAM
ATD has min and max
frequency requirements.
See Chapter 1, “Introduction”
and Appendix A, “Electrical
Characteristics.
FLASH
FLASH has frequency
requirements for program
and erase operation.
See Appendix A, “Electrical
Characteristics.
Figure 7-1. System Clock Distribution Diagram
NOTE
Freescale Semiconductor recommends that FLASH location $FFBE 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
97
Chapter 7 Internal Clock Generator (ICG) Module
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ
enabled (IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown
available when KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 7-2. Block Diagram Highlighting ICG Module
MC9S08GB/GT Data Sheet, Rev. 2.3
98
Freescale Semiconductor
Introduction
7.1
Introduction
Figure 7-3 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
REF
SELECT
VDDA
(SEE NOTE 2)
FREQUENCY
LOCKED
LOOP (FLL)
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 Figure 7-1 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 in
the Pins and Connections section for specifics.
Figure 7-3. ICG Block Diagram
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 7-3, 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.
• 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
99
Internal Clock Generator (ICG) Module
•
•
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).
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 7.4, “Initialization/Application
Information,” and pick an example that best suits the application needs.
7.1.1
Features
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
• 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
MC9S08GB/GT Data Sheet, Rev. 2.3
100
Freescale Semiconductor
External Signal Description
7.1.2
Modes of Operation
This is a high-level description only. Detailed descriptions of operating modes are contained in
Section 7.3, “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 out of 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 which 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 which 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 which 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.
7.2
7.2.1
External Signal Description
Overview
Table 7-1 shows the user-accessible signals available for the ICG.
Table 7-1. Signal Properties
Name
Function
Reset State
EXTAL
External clock/oscillator input
Analog input
XTAL
Oscillator output
Analog output
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
101
Internal Clock Generator (ICG) Module
7.2.2
Detailed Signal Descriptions
This section describes each pin signal in detail.
7.2.2.1
EXTAL— External Reference Clock / Oscillator Input
If the first write to the ICG control register 1 selected FLL engaged external or FLL bypassed modes, this
signal is the analog external/reference clock or the input of the oscillator circuit. If the first write to the ICG
control register 1 selected FLL engaged internal or self-clocked modes, this signal has no effect on the
ICG.
7.2.2.2
XTAL— Oscillator Output
If the first write to the ICG control register 1 selected FLL engaged external or FLL bypassed modes using
a crystal/resonator reference, this signal is the analog output of the oscillator amplifier circuit. In all other
cases, this signal has no effect on the ICG.
7.2.3
External Clock Connections
If an external clock is used, then the pins are connected as shown below.
ICG
EXTAL
XTAL
VSS
NOT CONNECTED
CLOCK INPUT
Figure 7-4. External Clock Connections
7.2.4
External Crystal/Resonator Connections
If an external crystal/resonator frequency reference is used, then the pins are connected as shown below.
Recommended component values are listed in Appendix A, “Electrical Characteristics.”
MC9S08GB/GT Data Sheet, Rev. 2.3
102
Freescale Semiconductor
Functional Description
ICG
EXTAL
VSS
XTAL
RS
C1
C2
RF
CRYSTAL OR RESONATOR
Figure 7-5. External Frequency Reference Connection
7.3
Functional Description
This section provides a functional description of each of the five operating modes of the ICG. Also covered
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.
7.3.1
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.
7.3.1.1
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.
7.3.1.2
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
103
Internal Clock Generator (ICG) Module
7.3.1.3
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.
7.3.2
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
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. Once ICGDCLK is considered stable, the ICG
automatically closes the loop by switching to FLL engaged (internal or external) as selected by the CLKS
bits.
MC9S08GB/GT Data Sheet, Rev. 2.3
104
Freescale Semiconductor
Functional Description
CLKST
REFERENCE
DIVIDER (/7)
ICGIRCLK
RANGE
CLKS
RFD
CLOCK
SELECT
CIRCUIT
REDUCED
FREQUENCY
DIVIDER (R)
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
RESET AND
INTERRUPT
CONTROL
ERCS
ICGIF
IRQ
RESET
LOLRE LOCRE
Figure 7-6. Detailed Frequency-Locked Loop Block Diagram
7.3.3
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.
7.3.3.1
FLL Engaged Internal Unlocked
FEI unlocked is a temporary state that is entered when FEI is entered and the count error (∆n) 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
105
Internal Clock Generator (ICG) Module
The ICG will remain in this state while the count error (∆n) 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.
7.3.3.2
FLL Engaged Internal Locked
FLL engaged internal locked is entered from FEI unlocked when the count error (∆n), 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 only updated once every four comparison cycles.
The update made is an average of the error measurements taken in the four previous comparisons.
7.3.4
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 is still
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.
7.3.5
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 7-7 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.
7.3.5.1
FLL Engaged External Unlocked
FEE unlocked is entered when FEE is entered and the count error (∆n) 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
106
Freescale Semiconductor
Functional Description
The ICG will remain in this state while the count error (∆n) 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. Once 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.
7.3.5.2
FLL Engaged External Locked
FEE locked is entered from FEE unlocked when the count error (∆n) 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 only updated once every four comparison cycles. The update made is an average
of the error measurements taken in the four previous comparisons.
7.3.6
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 7-3 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, ∆n. To
achieve locked status, ∆n must be between nlock (min) and nlock (max). Once the FLL has locked, ∆n must
stay between nunlock (min) and nunlock (max) to remain locked. If ∆n 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.
7.3.7
FLL Loss-of-Clock Detection
The reference clock and the DCO clock are monitored under different conditions (see Table 7-2). 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 cleared by software or until the MCU is reset. LOCS is cleared by reading
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
107
Internal Clock Generator (ICG) Module
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.
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 7-2. Clock Monitoring
CLKS
REFST
ERCS
External Reference
Clock
Monitored?
DCO Clock
Monitored?
0X or 11
X
Forced Low
No
No
10
0
Forced Low
No
No
10
1
Real-Time(1)
Yes(1)
No
0X
X
Forced Low
No
Yes(2)
10
0
Forced High
No
Yes(2)
10
1
Real-Time
Yes
Yes(2)
11
X
Real-Time
Yes
Yes(2)
FEI
(CLKST = 01)
0X
X
Forced Low
No
Yes
11
X
Real-Time
Yes
Yes
FBE
(CLKST = 10)
10
0
Forced High
No
No
10
1
Real-Time
Yes
No
11
X
Real-Time
Yes
Yes
Mode
Off
SCM
(CLKST = 00)
FEE
(CLKST = 11)
1. If ENABLE is high (waiting for external crystal start-up after exiting stop).
2. DCO clock will not be monitored until DCOS = 1 upon entering SCM from off or FLL bypassed external mode.
7.3.8
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 7-3 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
108
Freescale Semiconductor
Functional Description
Table 7-3. 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
Conditions(1)
for
CLKS = CLKST
Reason
CLKS ≠
CLKST
Off
(XX)
X
0
—
0
—
—
FBE
(10)
X
0
—
0
—
ERCS = 0
SCM
(00)
X
fICGIRCLK/7(2)
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/R(3)
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.
7.3.9
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 FBE mode. 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 7-5), N and R are determined by
MFD and RFD, respectively (see Table 7-6).
• LOCK = 1.
If the above conditions are not true, then XCLK is equal to BUSCLK.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
109
Internal Clock Generator (ICG) Module
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.
7.4
Initialization/Application Information
7.4.1
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.
Table 7-4. ICG Configuration Consideration
Clock Reference Source = Internal
FLL
Engaged
FLL
Bypassed
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)
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.
Clock Reference Source = External
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.
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.
1. 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 sake.
MC9S08GB/GT Data Sheet, Rev. 2.3
110
Freescale Semiconductor
Initialization/Application Information
Table 7-5. ICGOUT Frequency Calculation Options
Clock Scheme
SCM — self-clocked mode (FLL bypassed
internal)
P
Note
fICGDCLK / R
NA
Typical fICGOUT = 8 MHz
out of reset
fext / R
NA
(fIRG / 7)* 64*N / R
64
fext * P * N / R
Range = 0 ; P = 64
Range = 1; P = 1
FBE — FLL bypassed external
FEI — FLL engaged internal
fICGOUT(1)
FEE — FLL engaged external
Typical fIRG = 243 kHz
1. Ensure that fICGDCLK, which is equal to fICGOUT * R, does not exceed fICGDCLKmax.
Table 7-6. MFD and RFD Decode Table
MFD Value
Multiplication Factor (N)
RFD
Division Factor (R)
000
001
010
011
100
101
110
111
4
6
8
10
12
14
16
18
000
001
010
011
100
101
110
111
÷1
÷2
÷4
÷8
÷16
÷32
÷64
÷128
Register
Bit 7
6
5
ICGC1
0
RANGE
REFS
ICGC2
LOLRE
ICGS1
4
3
CLKS
MFD
CLKST
2
1
Bit 0
OSCSTEN
0(1)
0
LOCRE
RFD
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
0
0
0
DCOS
ICGS2
0
0
0
0
ICGFLTU
0
0
0
0
FLT
ICGFLTL
FLT
ICGTRM
TRIM
= Unimplemented or Reserved
1. This bit is reserved for Freescale Semiconductor internal use only. Any write operations to this register should
write a 0 to this bit.
Figure 7-7. ICG Register Set
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
111
Internal Clock Generator (ICG) Module
7.4.2
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. 7-1
N / R = 8.38 MHz /(32 kHz * 64) = 4 ; we can choose N = 4 and R =1
Eqn. 7-2
Solving for N / R gives:
The values needed in each register to set up the desired operation are:
ICGC1 = $38 (%00111000)
Bit 7
0
Bit 6
RANGE
0
Bit 5
REFS
1
Bits 4:3 CLKS
11
Bit 2
OSCSTEN 0
Bit 1
0
Bit 0
0
Unimplemented or reserved, always reads zero
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 in stop modes
Reserved for Freescale Semiconductor internal use; always write zero
Unimplemented or reserved, always reads zero
ICGC2 = $00 (%00000000)
Bit 7
LOLRE
0
Generates an interrupt request on loss of lock
Bits 6:4 MFD
000 Sets the MFD multiplication factor to 4
Bit 3
LOCRE
0
Generates an interrupt request on loss of clock
Bits 2:0 RFD
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
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 7-8 shows flow charts for three conditions requiring ICG initialization.
MC9S08GB/GT Data Sheet, Rev. 2.3
112
Freescale Semiconductor
Initialization/Application Information
RECOVERY FROM
RESET, STOP1, OR STOP2
INITIALIZE ICG
ICG1 = $38
ICG2 = $00
CHECK
FLL LOCK STATUS.
LOCK = 1?
QUICK RECOVERY FROM STOP
MINIMUM CURRENT DRAW IN STOP
RECOVERY FROM STOP3
OSCSTEN = 1
RECOVERY FROM STOP3
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 7-8. ICG Initialization for FEE in Example #1
7.4.3
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. 7-3
N / R = 40 MHz /(4 MHz * 1) = 10 ; We can choose N = 10 and R = 1
Eqn. 7-4
Solving for N / R gives:
The values needed in each register to set up the desired operation are:
ICGC1 = $78 (%01111000)
Bit 7
0
Unimplemented or reserved, always reads zero
Bit 6
RANGE
1
Configures oscillator for high-frequency range; FLL prescale factor is 1
Bit 5
REFS
1
Requests an oscillator
Bits 4:3 CLKS
11
FLL engaged, external reference clock mode
Bit 2
OSCSTEN 0
Disables the oscillator in stop modes
Bit 1
0
Reserved for Freescale Semiconductor internal use; always write zero
Bit 0
0
Unimplemented or reserved, always reads zero
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
113
Internal Clock Generator (ICG) Module
ICGC2 = $30 (%00110000)
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
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
RECOVERY FROM
RESET, STOP1, OR STOP2
RECOVERY
FROM STOP3
INITIALIZE ICG
ICG1 = $7A
ICG2 = $30
CHECK
FLL LOCK STATUS
LOCK = 1?
YES
SERVICE INTERRUPT
SOURCE (fBus = 4 MHz)
NO
CHECK
FLL LOCK STATUS
LOCK = 1?
NO
YES
CONTINUE
CONTINUE
Figure 7-9. ICG Initialization and Stop Recovery for Example #2
7.4.4
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).
MC9S08GB/GT Data Sheet, Rev. 2.3
114
Freescale Semiconductor
Initialization/Application Information
The clock scheme will be FLL engaged, internal (FEI). So
fICGOUT = (fIRG / 7) * P * N / R ; P = 64, fIRG = 243 kHz
Eqn. 7-5
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. 7-6
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
0
Bit 6
RANGE
0
Bit 5
REFS
1
Bits 4:3 CLKS
01
Bit 2
OSCSTEN 0
Bit 1
0
Bit 0
0
Unimplemented or reserved, always reads zero
Configures oscillator for low-frequency range; (don’t care)
Oscillator using crystal or resonator requested (don’t care)
FLL engaged, internal reference clock mode
Disables the oscillator in stop modes
Reserved for Freescale Semiconductor internal use; always write zero
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
ICGTRM = $xx
Bit 7:0 TRIM
Only need to write when trimming internal oscillator; done in separate
operation (see example #4)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
115
Internal Clock Generator (ICG) Module
RECOVERY
FROM STOP3
RECOVERY FROM
RESET, STOP1, OR STOP2
INITIALIZE ICG
ICG1 = $28
ICG2 = $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 7-10. ICG Initialization and Stop Recovery for Example #3
7.4.5
Example #4: Internal Clock Generator Trim
The internally generated clock source is guaranteed to have a period ± 25% of the nominal value. In some
case 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
116
Freescale Semiconductor
ICG Registers and Control Bits
Initial conditions:
1) Clock supplied from ATE has 500 µs 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 7-11. 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 7-11 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. Once the trim procedure is complete, the reduction divisor
can be restored. This will prevent accidental overshoot of the maximum clock frequency.
7.5
ICG Registers and Control Bits
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
117
Internal Clock Generator (ICG) Module
7.5.1
ICG Control Register 1 (ICGC1)
Bit 7
Read:
6
5
RANGE
REFS
1
0
4
3
2
1
OSCSTEN
0(1)
1
0
0
CLKS
Bit 0
0
Write:
Reset:
0
0
0
0
= Unimplemented or Reserved
1. This bit is reserved for Freescale Semiconductor internal use only. Any write operations to this register should write
a 0 to this bit.
Figure 7-12. ICG Control Register 1 (ICGC1)
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.
1 = Oscillator configured for high frequency range. FLL loop prescale factor P is 1.
0 = Oscillator configured for low frequency range. FLL loop prescale factor P is 64.
REFS — External Reference Select
The REFS bit controls the external reference clock source for ICGERCLK. The REFS bit is write-once
after a reset.
1 = Oscillator using crystal or resonator requested.
0 = External clock requested.
CLKS — Clock Mode Select
The CLKS bits control the clock mode according to Figure 7-13. 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.
Figure 7-13. CLKS Clock Select
CLKS[1:0]
Clock Mode
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).
MC9S08GB/GT Data Sheet, Rev. 2.3
118
Freescale Semiconductor
ICG Registers and Control Bits
OSCSTEN — Enable Oscillator in Off Mode
The OSCSTEN bit controls whether or not the oscillator circuit remains enabled when the ICG enters
off mode.
1 = Oscillator enabled when ICG is in off mode, CLKS = 1X and REFST = 1.
0 = Oscillator disabled when ICG is in off mode unless ENABLE is high, CLKS = 10, and
REFST = 1.
7.5.2
ICG Control Register 2 (ICGC2)
Bit 7
6
5
4
3
2
1
Bit 0
Read:
LOLRE
MFD
LOCRE
RFD
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 7-14. ICG Control Register 2 (ICGC2)
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.
1 = Generate a reset request on loss of lock.
0 = Generate an interrupt request on loss of lock.
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.
Table 7-7. MFD Multiplication Factor Select
MFD Value
Multiplication Factor (N)
000
4
001
6
010
8
011
10
100
12
101
14
110
16
111
18
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
119
Internal Clock Generator (ICG) Module
LOCRE — Loss of Clock Reset Enable
The LOCRE bit determines how the system handles a loss of clock condition.
1 = Generate a reset request on loss of clock.
0 = Generate an interrupt request on loss of clock.
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.
Table 7-8. RFD Reduced Frequency Divider Select
7.5.3
RFD
Division Factor (R)
000
÷1
001
÷2
010
÷4
011
÷8
100
÷16
101
÷32
110
÷64
111
÷128
ICG Status Register 1 (ICGS1)
Bit 7
Read:
6
CLKST
5
4
3
2
1
Bit 0
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
Write:
Reset:
1
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 7-15. ICG Status Register 1 (ICGS1)
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
ICG Registers and Control Bits
Table 7-9. CLKST Clock Mode Status
CLKST[1:0]
Clock Status
00
Self-clocked
01
FLL engaged, internal reference
10
FLL bypassed, external reference
11
FLL engaged, external reference
REFST — Reference Clock Status
The REFST bit indicates which clock reference is currently selected by the Reference Select circuit.
1 = Crystal/Resonator selected.
0 = External Clock selected.
LOLS — FLL Loss of Lock Status
The LOLS bit is an indication of FLL lock status. If LOLS is set, it remains set until cleared by
software or an MCU reset.
1 = FLL has unexpectedly lost lock since LOLS was last cleared, LOLRE determines action taken.
0 = FLL has not unexpectedly lost lock since LOLS was last cleared.
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.
1 = FLL is currently locked.
0 = FLL is currently unlocked.
LOCS — Loss Of Clock Status
The LOCS bit is an indication of ICG loss of clock status. If LOCS is set, it remains set until cleared
by software on an MCU reset.
1 = ICG has lost clock since LOCS was last cleared, LOCRE determines action taken.
0 = ICG has not lost clock since LOCS was last cleared.
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.
1 = External reference clock is stable, frequency requirement is met.
0 = External reference clock is not stable, frequency requirement is not met.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
121
Internal Clock Generator (ICG) Module
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 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 0 to ICGIF has no effect.
1 = An ICG interrupt request is pending.
0 = No ICG interrupt request is pending.
7.5.4
ICG Status Register 2 (ICGS2)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
DCOS
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented or Reserved
Figure 7-16. ICG Status Register 2 (ICGS2)
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.
1 = DCO clock is stable.
0 = DCO clock is unstable.
7.5.5
ICG Filter Registers (ICGFLTU, ICGFLTL)
Read:
Bit 15
14
13
12
0
0
0
0
11
10
9
Bit 8
0
0
FLT
Write:
Reset:
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 7-17. ICG Upper Filter Register (ICGFLTU)
MC9S08GB/GT Data Sheet, Rev. 2.3
122
Freescale Semiconductor
ICG Registers and Control Bits
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
Read:
FLT
Write:
Reset:
1
1
0
0
Figure 7-18. ICG Lower Filter Register (ICGFLTL)
The filter registers show the filter value (FLT).
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.
7.5.6
ICG Trim Register (ICGTRM)
7
6
5
4
3
2
1
0
Read:
TRIM
Write:
POR:
1
0
0
0
0
0
0
0
Reset:
U
U
U
U
U
U
U
U
U = Unaffected by MCU reset
Figure 7-19. ICG Trim Register (ICGTRM)
TRIM — 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
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Internal Clock Generator (ICG) Module
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
Chapter 8 Central Processor Unit (CPU)
8.1
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).
MC9S08GB/GT Data Sheet, Rev. 2.3
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125
Central Processor Unit (CPU)
8.2
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 $0000–$00FF
— 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
8.3
Programmer’s Model and CPU Registers
Figure 8-1 shows the five CPU registers. CPU registers are not part of the memory map.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
Programmer’s Model and CPU Registers
7
0
ACCUMULATOR
A
16-BIT INDEX REGISTER H:X
H INDEX REGISTER (HIGH)
15
8
INDEX REGISTER (LOW)
7
0
SP
STACK POINTER
15
X
0
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 8-1. CPU Registers
8.3.1
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.
8.3.2
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 $00 during reset. Reset has no effect
on the contents of X.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
127
Central Processor Unit (CPU)
8.3.3
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 $00FF 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 $00FF).
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.
8.3.4
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 $FFFE and $FFFF. The
vector stored there is the address of the first instruction that will be executed after exiting the reset state.
8.3.5
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/D.
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 8-2. Condition Code Register
MC9S08GB/GT Data Sheet, Rev. 2.3
128
Freescale Semiconductor
Programmer’s Model and CPU Registers
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.
1 = Overflow
0 = No overflow
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.
1 = Carry between bits 3 and 4
0 = No carry between bits 3 and 4
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.
1 = Interrupts disabled
0 = Interrupts enabled
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.
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.
1 = Negative result
0 = Non-negative result
Z — Zero Flag
The CPU sets the zero flag when an arithmetic operation, logic operation, or data manipulation
produces a result of $00 or $0000. 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.
1 = Zero result
0 = Non-zero result
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.
1 = Carry out of bit 7
0 = No carry out of bit 7
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
129
Central Processor Unit (CPU)
8.4
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.
8.4.1
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.
8.4.2
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.
8.4.3
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.
8.4.4
Direct Addressing Mode (DIR)
In direct addressing mode, the instruction includes the low-order eight bits of an address in the direct page
($0000–$00FF). During execution a 16-bit address is formed by concatenating an implied $00 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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Freescale Semiconductor
Addressing Modes
8.4.5
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).
8.4.6
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.
8.4.6.1
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.
8.4.6.2
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 + $0001) after the operand has been fetched. This addressing mode is only used for MOV and
CBEQ instructions.
8.4.6.3
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.
8.4.6.4
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 + $0001) after the operand has been fetched. This
addressing mode is used only for the CBEQ instruction.
8.4.6.5
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.
8.4.6.6
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
131
Central Processor Unit (CPU)
8.4.6.7
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.
8.5
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.
8.5.1
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 $FFFE and $FFFF and to fill the
instruction queue in preparation for execution of the first program instruction.
8.5.2
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
MC9S08GB/GT Data Sheet, Rev. 2.3
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Special Operations
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.
8.5.3
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.
8.5.4
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
133
Central Processor Unit (CPU)
8.5.5
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.
8.6
HCS08 Instruction Set Summary
Instruction Set Summary Nomenclature
The nomenclature listed here is used in the instruction descriptions in Table 8-1.
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 + $0001= 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
HCS08 Instruction Set Summary
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
0 = Bit forced to 0
1 = Bit forced to 1
= Bit set or cleared according to results of operation
U = Undefined after the operation
Machine coding notation
dd = Low-order 8 bits of a direct address $0000–$00FF (high byte assumed to be $00)
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 ($00xx).
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
135
Central Processor Unit (CPU)
rel —
Address modes
INH =
IMM =
DIR =
EXT =
IX =
IX+ =
IX1 =
IX1+ =
IX2
REL
SP1
SP2
=
=
=
=
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.
Inherent (no operands)
8-bit or 16-bit immediate
8-bit direct
16-bit extended
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
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
AND
AND
AND
AND
AND
AND
AND
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Add with Carry
Add without Carry
Add Immediate Value
(Signed) to Stack Pointer
Add Immediate Value
(Signed) to Index
Register (H:X)
Logical AND
A ← (A) + (M) + (C)
–
A ← (A) + (M)
–
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A9
B9
C9
D9
E9
F9
9ED9
9EE9
AB
BB
CB
DB
EB
FB
9EDB
9EEB
ii
dd
hh ll
ee ff
ff
ee ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
Bus Cycles1
Description
Operand
Operation
Opcode
Source
Form
Effect
on CCR
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 1 of 7)
2
3
4
4
3
3
5
4
2
3
4
4
3
3
5
4
SP ← (SP) + (M)
M is sign extended to a 16-bit value
– – – – – – 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)
0 – –
IMM
DIR
EXT
– IX2
IX1
IX
SP2
SP1
A4
B4
C4
D4
E4
F4
9ED4
9EE4
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
MC9S08GB/GT Data Sheet, Rev. 2.3
136
Freescale Semiconductor
HCS08 Instruction Set Summary
V H I N Z C
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
Arithmetic Shift Left
(Same as LSL)
BCS rel
Branch if Carry Bit Set
(Same as BLO)
Branch if Equal
Branch if Greater Than or
Equal To
(Signed Operands)
BGND
Enter Active Background
if ENBDM = 1
BGT rel
Branch if Greater Than
(Signed Operands)
Branch if Half Carry Bit
Clear
BHCC rel
BHCS rel
BHI rel
BHS rel
BIH rel
BIL rel
BIT #opr8i
BIT opr8a
BIT opr16a
BIT oprx16,X
BIT oprx8,X
BIT ,X
BIT oprx16,SP
BIT oprx8,SP
BLE rel
BLO rel
BLS rel
BLT rel
BMC rel
C
b7
Clear Bit n in Memory
BGE rel
b0
Arithmetic Shift Right
Branch if Carry Bit Clear
Branch if Half Carry Bit
Set
Branch if Higher
Branch if Higher or Same
(Same as BCC)
Branch if IRQ Pin High
Branch if IRQ Pin Low
Bit Test
Branch if Less Than
or Equal To
(Signed Operands)
Branch if Lower
(Same as BCS)
Branch if Lower or Same
Branch if Less Than
(Signed Operands)
Branch if Interrupt Mask
Clear
–
0
b7
BCLR n,opr8a
BEQ rel
C
–
b0
Branch if (C) = 0
– –
Mn ← 0
– –
DIR
INH
INH
–
IX1
IX
SP1
DIR
INH
INH
–
IX1
IX
SP1
– – – – REL
DIR (b0)
DIR (b1)
DIR (b2)
(b3)
– – – – DIR
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
38
48
58
68
78
9E68
37
47
57
67
77
9E67
24
11
13
15
17
19
1B
1D
1F
dd
ff
ff
dd
ff
ff
rr
dd
dd
dd
dd
dd
dd
dd
dd
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 2 of 7)
5
1
1
5
4
6
5
1
1
5
4
6
3
5
5
5
5
5
5
5
5
Branch if (C) = 1
– – – – – – REL
25 rr
3
Branch if (Z) = 1
– – – – – – REL
27 rr
3
Branch if (N ⊕ V) = 0
– – – – – – REL
90 rr
3
Waits For and Processes BDM
Commands Until GO, TRACE1, or
TAGGO
– – – – – – INH
82
5+
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
Branch if IRQ pin = 1
Branch if IRQ pin = 0
– – – – – – REL
– – – – – – REL
IMM
DIR
EXT
0 – –
– IX2
IX1
IX
SP2
SP1
2F rr
rr
ii
dd
hh ll
ee ff
ff
3
3
2
3
4
4
3
3
5
4
(A) & (M)
(CCR Updated but Operands
Not Changed)
2E
A5
B5
C5
D5
E5
F5
9ED5
9EE5
ee ff
ff
Branch if (Z) | (N ⊕ V) = 1
– – – – – – REL
93 rr
3
Branch if (C) = 1
– – – – – – REL
25 rr
3
Branch if (C) | (Z) = 1
– – – – – – REL
23 rr
3
Branch if (N ⊕ V ) = 1
– – – – – – REL
91 rr
3
Branch if (I) = 0
– – – – – – REL
2C rr
3
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
137
Central Processor Unit (CPU)
V H I N Z C
BMI rel
BMS rel
BNE rel
BPL rel
BRA rel
Branch if Minus
Branch if Interrupt Mask
Set
Branch if Not Equal
Branch if Plus
Branch Always
Branch if (N) = 1
– – – – – – REL
2B rr
3
Branch if (I) = 1
– – – – – – REL
2D rr
3
Branch if (Z) = 0
Branch if (N) = 0
No Test
– – – – – – REL
– – – – – – REL
– – – – – – REL
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
– – – – –
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
– – – – – – REL
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
– – – – –
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
DIR (b0)
DIR (b1)
DIR (b2)
(b3)
– – – – – – DIR
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
26
2A
20
01
03
05
07
09
0B
0D
0F
21
00
02
04
06
08
0A
0C
0E
10
12
14
16
18
1A
1C
1E
3
3
3
5
5
5
5
5
5
5
5
3
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
– – – – – – REL
AD rr
BRCLR n,opr8a,rel
Branch if Bit n in Memory
Clear
Branch if (Mn) = 0
BRN rel
Branch Never
Uses 3 Bus Cycles
BRSET n,opr8a,rel
Branch if Bit n in Memory
Set
BSET n,opr8a
Set Bit n in Memory
BSR rel
Branch to Subroutine
CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
CLC
CLI
CLR opr8a
CLRA
CLRX
CLRH
CLR oprx8,X
CLR ,X
CLR oprx8,SP
CMP #opr8i
CMP opr8a
CMP opr16a
CMP oprx16,X
CMP oprx8,X
CMP ,X
CMP oprx16,SP
CMP oprx8,SP
Compare and Branch if
Equal
Clear Carry Bit
Clear Interrupt Mask Bit
Clear
Compare Accumulator
with Memory
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 3 of 7)
Branch if (Mn) = 1
Mn ← 1
PC ← (PC) + $0002
push (PCL); SP ← (SP) – $0001
push (PCH); SP ← (SP) – $0001
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)
C←0
I←0
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
– – – – – –
– – – – – 0
– – 0 – – –
0 – – 0 1 –
(A) – (M)
(CCR Updated But Operands Not
Changed)
– –
DIR
IMM
IMM
IX1+
IX+
SP1
INH
INH
DIR
INH
INH
INH
IX1
IX
SP1
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
31
41
51
61
71
9E61
98
9A
3F
4F
5F
8C
6F
7F
9E6F
A1
B1
C1
D1
E1
F1
9ED1
9EE1
rr
rr
rr
dd
dd
dd
dd
dd
dd
dd
dd
rr
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
dd
ii
ii
ff
rr
ff
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
rr
5
rr
rr
rr
rr
rr
dd
ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
5
4
4
5
5
6
1
1
5
1
1
1
5
4
6
2
3
4
4
3
3
5
4
MC9S08GB/GT Data Sheet, Rev. 2.3
138
Freescale Semiconductor
HCS08 Instruction Set Summary
V H I N Z C
COM opr8a
COMA
COMX
COM oprx8,X
COM ,X
COM oprx8,SP
CPHX opr16a
CPHX #opr16i
CPHX opr8a
CPHX oprx8,SP
CPX #opr8i
CPX opr8a
CPX opr16a
CPX oprx16,X
CPX oprx8,X
CPX ,X
CPX oprx16,SP
CPX 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
Complement
(One’s Complement)
M ← (M)= $FF – (M)
A ← (A) = $FF – (A)
X ← (X) = $FF – (X)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
DIR
INH
1 INH
IX1
IX
SP1
EXT
IMM
DIR
SP1
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
33
43
53
63
73
9E63
3E
65
75
9EF3
A3
B3
C3
D3
E3
F3
9ED3
9EE3
INH
72
DIR
INH
– – – – – – INH
IX1
IX
SP1
DIR
INH
– –
– INH
IX1
IX
SP1
3B
4B
5B
6B
7B
9E6B
3A
4A
5A
6A
7A
9E6A
0 – –
Compare Index Register
(H:X) with Memory
(H:X) – (M:M + $0001)
(CCR Updated But Operands Not
Changed)
– –
Compare X (Index
Register Low) with
Memory
(X) – (M)
(CCR Updated But Operands Not
Changed)
– –
Decimal Adjust
Accumulator After ADD or
ADC of BCD Values
(A)10
Decrement and Branch if
Not Zero
Decrement A, X, or M
Branch if (result) ≠ 0
DBNZX Affects X Not H
Decrement
Divide
Exclusive OR
Memory with
Accumulator
Increment
Jump
Jump to Subroutine
M ← (M) – $01
A ← (A) – $01
X ← (X) – $01
M ← (M) – $01
M ← (M) – $01
M ← (M) – $01
A ← (H:A)÷(X)
H ← Remainder
A ← (A ⊕ M)
U – –
– – – –
0 – –
M ← (M) + $01
A ← (A) + $01
X ← (X) + $01
M ← (M) + $01
M ← (M) + $01
M ← (M) + $01
PC ← Jump Address
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
PC ← Unconditional Address
– –
–
–
– – – – – –
– – – – – –
INH
52
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
DIR
INH
INH
IX1
IX
SP1
DIR
EXT
IX2
IX1
IX
DIR
EXT
IX2
IX1
IX
A8
B8
C8
D8
E8
F8
9ED8
9EE8
3C
4C
5C
6C
7C
9E6C
BC
CC
DC
EC
FC
BD
CD
DD
ED
FD
dd
ff
ff
hh
jj
dd
ff
ii
dd
hh
ee
ff
ll
kk
ll
ff
ee ff
ff
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 4 of 7)
5
1
1
5
4
6
6
3
5
6
2
3
4
4
3
3
5
4
1
dd rr
rr
rr
ff rr
rr
ff rr
dd
ff
ff
7
4
4
7
6
8
5
1
1
5
4
6
6
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
2
3
4
4
3
3
5
4
5
1
1
5
4
6
3
4
4
3
3
5
6
6
5
5
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
139
Central Processor Unit (CPU)
V H I N Z C
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
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
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
MUL
NEG opr8a
NEGA
NEGX
NEG oprx8,X
NEG ,X
NEG oprx8,SP
NOP
NSA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
PSHA
PSHH
PSHX
Load Accumulator from
Memory
A ← (M)
Load Index Register (H:X)
from Memory
H:X ← (M:M + $0001)
Load X (Index Register
Low) from Memory
Logical Shift Left
(Same as ASL)
Logical Shift Right
0 – –
0 – –
X ← (M)
0 – –
C
0
b7
–
– –
b0
0
C
b7
IMM
DIR
EXT
– IX2
IX1
IX
SP2
SP1
IMM
DIR
EXT
– IX
IX2
IX1
SP1
– – 0
b0
(M)destination ← (M)source
Move
Unsigned multiply
Negate
(Two’s Complement)
No Operation
Nibble Swap
Accumulator
Inclusive OR Accumulator
and Memory
Push Accumulator onto
Stack
Push H (Index Register
High) onto Stack
Push X (Index Register
Low) onto Stack
H:X ← (H:X) + $0001 in
IX+/DIR and DIR/IX+ Modes
X:A ← (X) × (A)
M ← – (M) = $00 – (M)
A ← – (A) = $00 – (A)
X ← – (X) = $00 – (X)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
Uses 1 Bus Cycle
A ← (A[3:0]:A[7:4])
0 – –
–
– 0 – – – 0
– –
– – – – – –
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
DIR
INH
INH
IX1
IX
SP1
DIR
INH
INH
IX1
IX
SP1
DIR/DIR
DIR/IX+
IMM/DIR
IX+/DIR
INH
DIR
INH
INH
IX1
IX
SP1
INH
A6
B6
C6
D6
E6
F6
9ED6
9EE6
45
55
32
9EAE
9EBE
9ECE
9EFE
ii
dd
hh ll
ee ff
ff
AE
BE
CE
DE
EE
FE
9EDE
9EEE
38
48
58
68
78
9E68
34
44
54
64
74
9E64
4E
5E
6E
7E
42
30
40
50
60
70
9E60
9D
ee ff
ff
jj kk
dd
hh ll
ee ff
ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
dd
ff
ff
dd
ff
ff
dd dd
dd
ii dd
dd
dd
ff
ff
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 5 of 7)
2
3
4
4
3
3
5
4
3
4
5
5
6
5
5
2
3
4
4
3
3
5
4
5
1
1
5
4
6
5
1
1
5
4
6
5
5
4
5
5
5
1
1
5
4
6
1
– – – – – – INH
62
IMM
DIR
EXT
– IX2
IX1
IX
SP2
SP1
AA
BA
CA
DA
EA
FA
9EDA
9EEA
Push (A); SP ← (SP) – $0001
– – – – – – INH
87
2
Push (H); SP ← (SP) – $0001
– – – – – – INH
8B
2
Push (X); SP ← (SP) – $0001
– – – – – – INH
89
2
A ← (A) | (M)
0 – –
1
ii
dd
hh ll
ee ff
ff
ee ff
ff
2
3
4
4
3
3
5
4
MC9S08GB/GT Data Sheet, Rev. 2.3
140
Freescale Semiconductor
HCS08 Instruction Set Summary
V H I N Z C
PULA
PULH
PULX
ROL opr8a
ROLA
ROLX
ROL oprx8,X
ROL ,X
ROL oprx8,SP
ROR opr8a
RORA
RORX
ROR oprx8,X
ROR ,X
ROR oprx8,SP
Pull Accumulator from
Stack
Pull H (Index Register
High) from Stack
Pull X (Index Register
Low) from Stack
Rotate Left through Carry
RSP
Reset Stack Pointer
RTI
Return from Interrupt
RTS
Return from Subroutine
SBC #opr8i
SBC opr8a
SBC opr16a
SBC oprx16,X
SBC oprx8,X
SBC ,X
SBC oprx16,SP
SBC oprx8,SP
SEC
SEI
STA opr8a
STA opr16a
STA oprx16,X
STA oprx8,X
STA ,X
STA oprx16,SP
STA oprx8,SP
STHX opr8a
STHX opr16a
STHX oprx8,SP
STOP
STX
STX
STX
STX
STX
STX
STX
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
SP ← (SP + $0001); Pull (A)
– – – – – – INH
86
3
SP ← (SP + $0001); Pull (H)
– – – – – – INH
8A
3
SP ← (SP + $0001); Pull (X)
– – – – – – INH
88
3
DIR
INH
INH
IX1
IX
SP1
DIR
INH
INH
IX1
IX
SP1
39
49
59
69
79
9E69
36
46
56
66
76
9E66
– – – – – – INH
9C
1
INH
80
9
– – – – – – INH
81
6
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
INH
INH
DIR
EXT
IX2
IX1
IX
SP2
SP1
DIR
EXT
SP1
A2
B2
C2
D2
E2
F2
9ED2
9EE2
99
9B
B7
C7
D7
E7
F7
9ED7
9EE7
35
96
9EFF
– – 0 – – – INH
8E
DIR
EXT
IX2
– IX1
IX
SP2
SP1
BF
CF
DF
EF
FF
9EDF
9EEF
C
– –
b7
Rotate Right through
Carry
Subtract with Carry
Set Carry Bit
Set Interrupt Mask Bit
Store Accumulator in
Memory
Store H:X (Index Reg.)
Enable Interrupts:
Stop Processing
Refer to MCU
Documentation
Store X (Low 8 Bits of
Index Register)
in Memory
Bus Cycles1
Description
Operand
Operation
Opcode
Effect
on CCR
Source
Form
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 6 of 7)
b0
C
b7
– –
b0
SP ← $FF
(High Byte Not Affected)
SP ← (SP) + $0001; Pull (CCR)
SP ← (SP) + $0001; Pull (A)
SP ← (SP) + $0001; Pull (X)
SP ← (SP) + $0001; Pull (PCH)
SP ← (SP) + $0001; Pull (PCL)
SP ← SP + $0001; Pull (PCH)
SP ← SP + $0001; Pull (PCL)
A ← (A) – (M) – (C)
C←1
I←1
M ← (A)
(M:M + $0001) ← (H:X)
I bit ← 0; Stop Processing
M ← (X)
– –
– – – – – 1
– – 1 – – –
0 – –
0 – –
0 – –
–
–
dd
ff
ff
dd
ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
dd
hh ll
ee ff
ff
ee ff
ff
dd
hh ll
ff
5
1
1
5
4
6
5
1
1
5
4
6
2
3
4
4
3
3
5
4
1
1
3
4
4
3
2
5
4
4
5
5
2+
dd
hh ll
ee ff
ff
ee ff
ff
3
4
4
3
2
5
4
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
141
Central Processor Unit (CPU)
Description
V H I N Z C
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Subtract
SWI
Software Interrupt
TAP
Transfer Accumulator to
CCR
Transfer Accumulator to
X (Index Register Low)
Transfer CCR to
Accumulator
TAX
TPA
TST opr8a
TSTA
TSTX
TST oprx8,X
TST ,X
TST oprx8,SP
TSX
TXA
TXS
WAIT
1
Test for Negative or Zero
Transfer SP to Index Reg.
Transfer X (Index Reg.
Low) to Accumulator
Transfer Index Reg. to SP
Enable Interrupts; Wait
for Interrupt
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A0
B0
C0
D0
E0
F0
9ED0
9EE0
– – 1 – – – INH
83
11
INH
84
1
X ← (A)
– – – – – – INH
97
1
A ← (CCR)
– – – – – – INH
85
1
(M) – $00
(A) – $00
(X) – $00
(M) – $00
(M) – $00
(M) – $00
H:X ← (SP) + $0001
DIR
INH
0 – –
– INH
IX1
IX
SP1
– – – – – – INH
3D dd
4D
5D
6D ff
7D
9E6D ff
95
4
1
1
4
3
5
2
A ← (X)
– – – – – – INH
9F
1
SP ← (H:X) – $0001
– – – – – – INH
94
2
I bit ← 0; Halt CPU
– – 0 – – – INH
8F
2+
A ← (A) – (M)
PC ← (PC) + $0001
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
Push (X); SP ← (SP) – $0001
Push (A); SP ← (SP) – $0001
Push (CCR); SP ← (SP) – $0001
I ← 1;
PCH ← Interrupt Vector High Byte
PCL ← Interrupt Vector Low Byte
– –
CCR ← (A)
ii
dd
hh ll
ee ff
ff
Bus Cycles1
Operation
Operand
Effect
on CCR
Opcode
Source
Form
Address
Mode
Table 8-1. HCS08 Instruction Set Summary (Sheet 7 of 7)
ee ff
ff
2
3
4
4
3
3
5
4
Bus clock frequency is one-half of the CPU clock frequency.
MC9S08GB/GT Data Sheet, Rev. 2.3
142
Freescale Semiconductor
HCS08 Instruction Set Summary
Table 8-2. 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
DIR 2
5 2F
TST
REL 2
3 3E
CPHX
REL 3
3 3F
BIH
CLR
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
DEC
ROL
DEC
DBNZ
INH 3
1 6C
DBNZ
INC
INH 2
1 6D
INC
IX1 1
4 7D
TST
INH 2
5 6E
MOV
CLRX
IX1 1
CLR
ADD
INH 2
1
INH 1
2
BD
BSR
Page 2
WAIT
5
1
JSR
REL 2
2 BE
LDX
2
AF
TXA
INH 2
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
JSR
DIR 3
3 CE
LDX
IMM 2
2 BF
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
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 2
AE
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
INH
1 AD
NOP
IX 1
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
RSP
1
2+ 9E
STOP
ADC
SBC
BIT
LDA
DIR 3
3 C9
IMM 2
2 BA
ORA
SEI
INH 1
9D
IX
5 8E
MOV
ADC
INH 2
1 AB
INH 1
1 9C
CLRH
IX 1
3
IMD 2
IX+D 1
5 7F
4 8F
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
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
2 97
PULX
IX 1
4 89
IX1 1
5 7A
INH 2
4 6B
IX1+
LSL
STHX
PSHA
IX 1
4 88
IX1 1
5 79
INH 2
1 6A
SP1
SP2
IX+
ASR
LSL
INH 2
1 69
PULA
IX 1
4 87
IX1 1
5 78
DD 2
DIX+ 3
1 5F
1 6F
CLRA
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
TSTX
INH 1
5 5E
MOV
EXT 3
5 4F
REL 2
REL
IX
IX1
IX2
IMD
DIX+
TSTA
DIR 1
6 4E
INH 2
1 67
INCX
INH 1
1 5D
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
ROR
DBNZX
INH 2
1 5C
INCA
DIR 1
4 4D
CPHX
DIR 3
1 66
DECX
INH 1
4 5B
DBNZA
DIR 2
5 4C
REL 2
3 3D
BIL
DECA
DIR 1
7 4B
DBNZ
BMS
DIR 2
5 2E
Inherent
Immediate
Direct
Extended
DIR to DIR
IX+ to DIR
DEC
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
3 75
ROLX
INH 1
1 5A
DAA
3
BGE
INH 2
6 91
IX+ 1
1 82
LSR
LSLX
INH 1
1 59
CBEQ
IX1 1
5 74
INH 2
4 65
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
COM
RTI
IX 1
5 81
INH 1
5 73
INH 2
1 64
RORX
ASRA
DIR 1
5 48
REL 2
3 3A
DIR 2
5 2B
BSET7
DIR 2
5 1F
ASR
BHCS
BPL
RORA
DIR 1
5 47
REL 2
3 39
DIR 2
5 2A
BCLR6
DIR 2
5 1E
ROR
INH 1
1 63
Control
9 90
80
NEG
NSA
LDHX
IMM 2
1 56
4
IX1+ 2
1 72
LSRX
INH 1
3 55
LDHX
DIR 3
5 46
BHCC
DIR 2
5 29
BSET6
DIR 2
5 1D
STHX
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
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
143
Central Processor Unit (CPU)
Table 8-2. 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+
Note: All Sheet 2 Opcodes are Preceded by the Page 2 Prebyte (9E)
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
Prebyte (9E) and Opcode in
Hexadecimal 9E60
6
HCS08 Cycles
Instruction Mnemonic
SP1 Addressing Mode
NEG
Number of Bytes 3
MC9S08GB/GT Data Sheet, Rev. 2.3
144
Freescale Semiconductor
Chapter 9 Keyboard Interrupt (KBI) Module
9.1
Introduction
The MC9S08GB/GT has one KBI module with eight keyboard interrupt inputs that share port A pins. See
Chapter 2, “Pins and Connections” for more information about the logic and hardware aspects of these
pins.
9.1.1
Port A and Keyboard Interrupt Pins
MCU Pin:
PTA7/
KBI1P7
PTA6/
KBI1P6
PTA5/
KBI1P5
PTA4/
KBI1P4
PTA3/
KBI1P3
PTA2/
KBI1P2
PTA1/
KBI1P1
PTA0/
KBI1P0
Figure 9-1. Port A Pin Names
The following paragraphs discuss controlling the keyboard interrupt pins.
Port A is an 8-bit port which is shared among the KBI keyboard interrupt inputs and general-purpose I/O.
The eight KBIPEn control bits in the KBIPE register allow selection of any combination of port A pins to
be assigned as KBI inputs. Any pins which are enabled as KBI inputs will be forced to act as inputs and
the remaining port A pins are available as general-purpose I/O pins controlled by the port A data (PTAD),
data direction (PTADD), and pullup enable (PTAPE) registers.
KBI inputs can be configured for edge-only sensitivity or edge-and-level sensitivity. Bits 3 through 0 of
port A are falling-edge/low-level sensitive while bits 7 through 4 can be configured for
rising-edge/high-level or for falling-edge/low-level sensitivity.
The eight PTAPEn control bits in the PTAPE register allow you to select whether an internal pullup device
is enabled on each port A pin that is configured as an input. When any of bits 7 through 4 of port A are
enabled as KBI inputs and are configured to detect rising edges/high levels, the pullup enable bits enable
pulldown rather than pullup devices.
An enabled keyboard interrupt can be used to wake the MCU from wait or standby (stop3).
9.2
Features
The keyboard interrupt (KBI) module features include:
• Keyboard interrupts selectable on eight port pins:
— 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 or wait mode
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
145
Chapter 9 Keyboard Interrupt (KBI) Module
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available
when KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 9-2. Block Diagram Highlighting KBI Module
MC9S08GB/GT Data Sheet, Rev. 2.3
146
Freescale Semiconductor
KBI Block Diagram
9.3
KBI Block Diagram
Figure 9-3 shows the block diagram for a KBI module.
KBI1P0
KBIPE0
KBIPE3
VDD
0
RESET
SYNCHRONIZER
CK
S
KBIPE4
KEYBOARD
INTERRUPT FF
KBEDG4
0
STOP
STOP BYPASS
KEYBOARD
INTERRUPT
REQUEST
KBIMOD
1
KBI1Pn
KBF
D CLR Q
1
KBI1P4
BUSCLK
KBACK
KBI1P3
KBIE
S
KBIPEn
KBEDGn
Figure 9-3. KBI Block Diagram
The KBI module allows up to eight pins to act as additional interrupt sources. Four of these pins allow
falling-edge sensing while the other four can be configured for either rising-edge sensing or falling-edge
sensing. The sensing mode for all eight pins can also be modified to detect edges and levels instead of only
edges.
9.4
Keyboard Interrupt (KBI) Module
This on-chip peripheral module is called a keyboard interrupt (KBI) module because originally it was
designed to simplify the connection and use of row-column matrices of keyboard switches. However, these
inputs are also useful as extra external interrupt inputs and as an external means of waking up the MCU
from stop or wait low-power modes.
9.4.1
Pin Enables
The KBIPEn control bits in the KBI1PE 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 KBI1PE are
general-purpose I/O pins that are not associated with the KBI module.
9.4.2
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
147
Keyboard Interrupt (KBI) Module
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.
9.4.3
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 KBI1SC 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.
9.5
KBI Registers and Control Bits
This section provides information about all registers and control bits associated with the KBI modules.
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.
9.5.1
KBI Status and Control Register (KBI1SC)
Bit 7
6
5
4
Read:
3
2
KBF
0
KBEDG7 KBEDG6 KBEDG5 KBEDG4
Write:
Reset:
1
Bit 0
KBIE
KBIMOD
0
0
KBACK
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 9-4. KBI Status and Control Register (KBI1SC)
MC9S08GB/GT Data Sheet, Rev. 2.3
148
Freescale Semiconductor
KBI Registers and Control Bits
KBEDGn — Keyboard Edge Select for KBI Port Bit n (n = 7–4)
Each of these read/write bits selects the polarity of the edges and/or 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.
1 = Rising edges/high levels.
0 = Falling edges/low levels.
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.
1 = KBI interrupt pending.
0 = No KBI interrupt pending.
KBF can be used as a software pollable flag (KBIE = 0) or it can generate a hardware interrupt request
to the CPU (KBIE = 1).
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.
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.
1 = KBI hardware interrupt requested when KBF = 1.
0 = KBF does not generate hardware interrupts (use polling).
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)
1 = Edge-and-level detection.
0 = Edge-only detection.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
149
Keyboard Interrupt (KBI) Module
9.5.2
KBI Pin Enable Register (KBI1PE)
Bit 7
6
5
4
3
2
1
Bit 0
KBIPE7
KBIPE6
KBIPE5
KBIPE4
KBIPE3
KBIPE2
KBIPE1
KBIPE0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 9-5. KBI Pin Enable Register (KBI1PE)
KBIPEn — Keyboard Pin Enable for KBI Port Bit n (n = 7–0)
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.
1 = Bit n of KBI port enabled as a keyboard interrupt input
0 = Bit n of KBI port is a general-purpose I/O pin not associated with the KBI.
MC9S08GB/GT Data Sheet, Rev. 2.3
150
Freescale Semiconductor
Chapter 10 Timer/PWM (TPM) Module
10.1
Introduction
The MC9S08GB/GT includes two 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 of these two TPMs, 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 3-channel 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 either of the TPM modules allows the
TPM prescaler to run using the oscillator rate divided by two (ICGERCLK/2). This clock source must be
selected only if the ICG is configured in either FBE or FEE mode. In FBE mode, this selection is redundant
because the BUSCLK frequency is the same as XCLK. In FEE mode, the proper conditions must be met
for XCLK to equal ICGERCLK/2 (see Section 7.3.9, “Fixed Frequency Clock”). Selecting XCLK as the
clock source with the ICG in either FEI or SCM mode will result in the TPM being non-functional.
10.2
Features
The timer system in the MC9S08GB60 includes a 3-channel TPM1 and a separate 5-channel TPM2; the
timer system in the MC9S08GB32 includes two 2-channel modules, TPM1 and TPM2. Timer system
features include:
• A total of 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
• Prescale taps for divide by 1, 2, 4, 8, 16, 32, 64, or 128
• 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 terminal count interrupt
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
151
Chapter 10 Timer/PWM (TPM) Module
RTI
COP
IRQ
LVD
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available
when KBI enabled (KBIPn = 1).
PORT B
NOTE 1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
PTB7/AD1P7–
PTB0/AD1P0
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
IIC MODULE (IIC1)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
VDDAD
VSSAD
VREFH
VREFL
8
NOTES 1, 5
NOTE 1
8
PORT G
IRQ
NOTES
2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 10-1. Block Diagram Highlighting the TPM Modules
MC9S08GB/GT Data Sheet, Rev. 2.3
152
Freescale Semiconductor
TPM Block Diagram
10.3
TPM Block Diagram
The TPM uses one input/output (I/O) pin per channel, TPMxCHn where x is the TPM number (for
example, 1 or 2) and n is the channel number (for example, 0–4). The TPM shares its I/O pins with
general-purpose I/O port pins (refer to the Pins and Connections chapter for more information).
Figure 10-2 shows the structure of a TPM. Some MCUs include more than one TPM, with various
numbers of channels.
BUSCLK
XCLK
SYNC
CLOCK SOURCE
SELECT
OFF, BUS, XCLK, EXT
PRESCALE AND SELECT
DIVIDE BY
1, 2, 4, 8, 16, 32, 64, or 128
TPMx) EXT CLK
CLKSB
PS2
CLKSA
PS1
PS0
CPWMS
MAIN 16-BIT COUNTER
TOF
COUNTER RESET
INTERRUPT
LOGIC
TOIE
16-BIT COMPARATOR
TPMxMODH:TPMx
CHANNEL 0
ELS0B ELS0A
PORT
LOGIC
16-BIT COMPARATOR
TPMxC0VH:TPMxC0VL
CH0F
INTERRUPT
LOGIC
16-BIT LATCH
INTERNAL BUS
CHANNEL 1
MS0B
MS0A
ELS1B
ELS1A
CH0IE
PORT
LOGIC
16-BIT COMPARATOR
TPMxCH1
CH1F
TPMxC1VH:TPMxC1VL
INTERRUPT
LOGIC
16-BIT LATCH
MS1A
ELSnB
ELSnA
CH1IE
...
PORT
LOGIC
16-BIT COMPARATOR
TPMxCnVH:TPMxCnVL
...
MS1B
...
CHANNEL n
TPMxCH0
TPMxCHn
CHnF
16-BIT LATCH
MSnB
MSnA
CHnIE
INTERRUPT
LOGIC
Figure 10-2. TPM Block Diagram
The central component of the TPM is the 16-bit counter that can operate as a free-running counter, a
modulo counter, or an up-/down-counter when the TPM is configured for center-aligned PWM. The TPM
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
153
Timer/PWM (TPM) Module
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 $0000 or $FFFF
effectively make the counter free running.) Software can read the counter value at any time without
affecting the counting sequence. Any write to either byte of the TPMxCNT counter resets the counter
regardless of the data value written.
All TPM channels are programmable independently as input capture, output compare, or buffered
edge-aligned PWM channels.
10.4
Pin Descriptions
Table 10-1 shows the MCU pins related to the TPM modules. When TPMxCH0 is used as an external
clock input, the associated TPM channel 0 can not use the pin. (Channel 0 can still be used in output
compare mode as a software timer.) When any of the pins associated with the timer is configured as a timer
input, a passive pullup can be enabled. After reset, the TPM modules are disabled and all pins default to
general-purpose inputs with the passive pullups disabled.
10.4.1
External TPM Clock Sources
When control bits CLKSB:CLKSA in the timer status and control register are set to 1:1, the prescaler and
consequently the 16-bit counter for TPMx are driven by an external clock source connected to the
TPMxCH0 pin. A synchronizer is needed between the external clock and the rest of the TPM. This
synchronizer is clocked by the bus clock so the frequency of the external source must be less than one-half
the frequency of the bus rate clock. The upper frequency limit for this external clock source is specified to
be one-fourth the bus frequency to conservatively accommodate duty cycle and phase-locked loop (PLL)
or frequency-locked loop (FLL) frequency jitter effects.
When the TPM is using the channel 0 pin for an external clock, the corresponding ELS0B:ELS0A control
bits should be set to 0:0 so channel 0 is not trying to use the same pin.
10.4.2
TPMxCHn — TPMx Channel n I/O Pins
Each TPM channel is associated with an I/O pin on the MCU. The function of this pin depends on the
configuration of the channel. In some cases, no pin function is needed so the pin reverts to being controlled
by general-purpose I/O controls. When a timer has control of a port pin, the port data and data direction
registers do not affect the related pin(s). See the Pins and Connections chapter for additional information
about shared pin functions.
10.5
Functional Description
All TPM functions are associated with a main 16-bit counter that allows flexible selection of the clock
source and prescale divisor. A 16-bit modulo register also is associated with the main 16-bit counter in the
TPM. Each TPM channel is optionally associated with an MCU pin and a maskable interrupt function.
The TPM has center-aligned PWM capabilities controlled by the CPWMS control bit in TPMxSC. When
CPWMS is set to 1, timer counter TPMxCNT changes to an up-/down-counter and all channels in the
MC9S08GB/GT Data Sheet, Rev. 2.3
154
Freescale Semiconductor
Functional Description
associated TPM act as center-aligned PWM channels. When CPWMS = 0, each channel can
independently be configured to operate in input capture, output compare, or buffered edge-aligned PWM
mode.
The following sections describe the main 16-bit 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 on the operating mode, these topics are covered in the associated mode
sections.
10.5.1
Counter
All timer functions are based on the main 16-bit counter (TPMxCNTH:TPMxCNTL). This section
discusses selection of the clock source, up-counting vs. up-/down-counting, end-of-count overflow, and
manual counter reset.
After any MCU reset, CLKSB:CLKSA = 0:0 so no clock source is selected and the TPM is inactive.
Normally, CLKSB:CLKSA would be set to 0:1 so the bus clock drives the timer counter. The clock source
for each of the TPM can be independently selected to be off, the bus clock (BUSCLK), the fixed system
clock (XCLK), or an external input through the TPMxCH0 pin. The maximum frequency allowed for the
external clock option is one-fourth the bus rate. Refer to Section 10.7.1, “Timer x Status and Control
Register (TPMxSC),” and Table 10-1 for more information about clock source selection.
When the microcontroller is in active background mode, the TPM temporarily suspends all counting until
the microcontroller returns to normal user operating mode. During stop mode, all TPM clocks are stopped;
therefore, the TPM is effectively disabled until clocks resume. During wait mode, the TPM continues to
operate normally.
The main 16-bit 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 main 16-bit counter counts from $0000 through its terminal count and then continues
with $0000. The terminal count is $FFFF or a modulus value in TPMxMODH:TPMxMODL.
When center-aligned PWM operation is specified, the counter counts upward from $0000 through its
terminal count and then counts downward to $0000 where it returns to up-counting. Both $0000 and the
terminal count value (value in TPMxMODH:TPMxMODL) are normal length counts (one timer clock
period long).
An interrupt flag and enable are associated with the main 16-bit counter. The timer overflow 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 automatically generated whenever the TOF flag is 1.
The conditions that cause TOF to become set depend on the counting mode (up or up/down). In
up-counting mode, the main 16-bit counter counts from $0000 through $FFFF and overflows to $0000 on
the next counting clock. TOF becomes set at the transition from $FFFF to $0000. When a modulus limit
is set, TOF becomes set at the transition from the value set in the modulus register to $0000. When the
main 16-bit counter is operating in up-/down-counting mode, the TOF flag gets set as the counter changes
direction at the transition from the value set in the modulus register and the next lower count value. This
corresponds to the end of a PWM period. (The $0000 count value corresponds to the center of a period.)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
155
Timer/PWM (TPM) Module
Because the HCS08 MCU is an 8-bit architecture, a coherency mechanism is built into the timer counter
for read operations. Whenever either byte of the counter is read (TPMxCNTH or TPMxCNTL), both bytes
are captured into a buffer so when the other byte is read, the value will represent the other byte of the count
at the time the first byte was read. The counter continues to count normally, but no new value can be read
from either byte until both bytes of the old count have been read.
The main timer counter can be reset manually at any time by writing any value to either byte of the timer
count TPMxCNTH or TPMxCNTL. Resetting the counter in this manner also resets the coherency
mechanism in case only one byte of the counter was read before resetting the count.
10.5.2
Channel Mode Selection
Provided CPWMS = 0 (center-aligned PWM operation is not specified), 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 buffered edge-aligned PWM.
10.5.2.1 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.
When either byte of the 16-bit capture register is read, both bytes are latched into a buffer to support
coherent 16-bit accesses regardless of 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) that can optionally generate a CPU interrupt request.
10.5.2.2 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.
In output compare mode, values are transferred to the corresponding timer channel value registers only
after both 8-bit bytes of a 16-bit register have been written. This coherency sequence can be manually reset
by writing to the channel status/control register (TPMxCnSC).
An output compare event sets a flag bit (CHnF) that can optionally generate a CPU interrupt request.
10.5.2.3 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 setting in the modulus register
(TPMxMODH:TPMxMODL). The duty cycle is determined by the setting in the timer channel value
MC9S08GB/GT Data Sheet, Rev. 2.3
156
Freescale Semiconductor
Functional Description
register (TPMxCnVH:TPMxCnVL). The polarity of this PWM signal is determined by the setting in the
ELSnA control bit. Duty cycle cases of 0 percent and 100 percent are possible.
As Figure 10-3 shows, the output compare value in the TPM channel registers determines the pulse width
(duty cycle) of the PWM signal. 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
TPMxC
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Figure 10-3. PWM Period and Pulse Width (ELSnA = 0)
When the channel value register is set to $0000, the duty cycle is 0 percent. By setting the timer channel
value register (TPMxCnVH:TPMxCnVL) to a value greater than the modulus setting, 100 percent duty
cycle can be achieved. This implies that the modulus setting must be less than $FFFF to get 100 percent
duty cycle.
Because the HCS08 is a family of 8-bit MCUs, the settings in the timer channel registers are buffered to
ensure coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to either register,
TPMxCnVH or TPMxCnVL, write to buffer registers. In edge-PWM mode, values are transferred to the
corresponding timer channel registers only after both 8-bit bytes of a 16-bit register have been written and
the value in the TPMxCNTH:TPMxCNTL counter is $0000. (The new duty cycle does not take effect until
the next full period.)
10.5.3
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 and the period is determined by the value in TPMxMODH:TPMxMODL.
TPMxMODH:TPMxMODL should be kept in the range of $0001 to $7FFF 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);
for TPMxMODH:TPMxMODL = $0001–$7FFF
Eqn. 10-1
Eqn. 10-2
If the channel value register TPMxCnVH:TPMxCnVL is zero or negative (bit 15 set), the duty cycle will
be 0 percent. If TPMxCnVH:TPMxCnVL is a positive value (bit 15 clear) and is greater than the (nonzero)
modulus setting, the duty cycle will be 100 percent because the duty cycle compare will never occur. This
implies the usable range of periods set by the modulus register is $0001 through $7FFE ($7FFF if
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
157
Timer/PWM (TPM) Module
generation of 100 percent duty cycle is not necessary). This is not a significant limitation because the
resulting period is much longer than required for normal applications.
TPMxMODH:TPMxMODL = $0000 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 $0000 through $FFFF,
but when CPWMS = 1 the counter needs a valid match to the modulus register somewhere other than at
$0000 in order to change directions from up-counting to down-counting.
Figure 10-4 shows the output compare value in the TPM channel registers (multiplied by 2), which
determines the pulse width (duty cycle) of the CPWM signal. If ELSnA = 0, the compare match while
counting up forces the CPWM output signal low and a compare match 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
COUNT =
TPMxMODH:TPMx
OUTPUT
COMPARE
(COUNT UP)
OUTPUT
COMPARE
(COUNT DOWN)
COUNT =
TPMxMODH:TPMx
TPM1C
PULSE WIDTH
2x
2x
PERIOD
Figure 10-4. 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.
Because the HCS08 is a family of 8-bit MCUs, 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. Values are
transferred to the corresponding timer channel registers only after both 8-bit bytes of a 16-bit register have
been written and the timer counter overflows (reverses direction from up-counting to down-counting at the
end of the terminal count in the modulus register). This TPMxCNT overflow requirement only applies to
PWM channels, not output compares.
Optionally, when TPMxCNTH:TPMxCNTL = TPMxMODH:TPMxMODL, the TPM can generate a TOF
interrupt at the end of this count. The user can choose to reload any number of the PWM buffers, and they
will all update simultaneously at the start of a new period.
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
158
Freescale Semiconductor
TPM Interrupts
10.6
TPM Interrupts
The TPM generates an optional interrupt for the main counter overflow and an interrupt for each channel.
The meaning of channel interrupts depends on the mode of operation for each channel. 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. See the Resets,
Interrupts, and System Configuration chapter for absolute interrupt vector addresses, priority, and local
interrupt mask control bits.
For each interrupt source in the TPM, a flag bit is set on 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
verify 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 be generated
whenever the associated interrupt flag equals 1. It is the responsibility of user software to perform a
sequence of steps to clear the interrupt flag before returning from the interrupt service routine.
10.6.1
Clearing Timer Interrupt Flags
TPM interrupt flags are cleared by a 2-step process that includes a read of the flag bit while it is set (1)
followed by a write of 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.
10.6.2
Timer Overflow Interrupt Description
The conditions that cause TOF to become set depend on the counting mode (up or up/down). In
up-counting mode, the 16-bit timer counter counts from $0000 through $FFFF and overflows to $0000 on
the next counting clock. TOF becomes set at the transition from $FFFF to $0000. When a modulus limit
is set, TOF becomes set at the transition from the value set in the modulus register to $0000. When the
counter is operating in up-/down-counting mode, the TOF flag gets set as the counter changes direction at
the transition from the value set in the modulus register and the next lower count value. This corresponds
to the end of a PWM period. (The $0000 count value corresponds to the center of a period.)
10.6.3
Channel Event Interrupt Description
The meaning of channel interrupts depends on the current mode of the channel (input capture, output
compare, edge-aligned PWM, or center-aligned PWM).
When a channel is configured as an input capture channel, the ELSnB:ELSnA control bits select rising
edges, falling edges, any edge, or no edge (off) as the edge that triggers an input capture event. When the
selected edge is detected, the interrupt flag is set. The flag is cleared by the 2-step sequence described in
Section 10.6.1, “Clearing Timer Interrupt Flags.”
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 2-step
sequence described in Section 10.6.1, “Clearing Timer Interrupt Flags.”
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
159
Timer/PWM (TPM) Module
10.6.4
PWM End-of-Duty-Cycle Events
For channels that are configured for PWM operation, there are two possibilities:
• When the channel is configured for edge-aligned PWM, the channel flag is set when the timer
counter matches the channel value register that 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, which are the times when the timer counter matches the
channel value register.
The flag is cleared by the 2-step sequence described in Section 10.6.1, “Clearing Timer Interrupt Flags.”
10.7
TPM Registers and Control Bits
The TPM includes:
• An 8-bit status and control register (TPMxSC)
• A 16-bit counter (TPMxCNTH:TPMxCNTL)
• A 16-bit modulo register (TPMxMODH:TPMxMODL)
Each timer channel has:
• An 8-bit status and control register (TPMxCnSC)
• A 16-bit channel value register (TPMxCnVH:TPMxCnVL)
Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address
assignments for all TPM 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 MCU systems have more than one TPM, 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 and TPM1C2SC is the status and control register for timer 1, channel 2.
10.7.1
Timer x Status and Control Register (TPMxSC)
TPMxSC contains the overflow status flag and control bits that are used to configure the interrupt enable,
TPM configuration, clock source, and prescale divisor. These controls relate to all channels within this
timer module.
Bit 7
Read:
6
5
4
3
2
1
Bit 0
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
0
0
0
0
0
0
0
TOF
Write:
Reset:
0
= Unimplemented or Reserved
Figure 10-5. Timer x Status and Control Register (TPMxSC)
MC9S08GB/GT Data Sheet, Rev. 2.3
160
Freescale Semiconductor
TPM Registers and Control Bits
TOF — Timer Overflow Flag
This flag is set when the TPM counter changes to $0000 after reaching the modulo value programmed
in the TPM counter modulo registers. When the TPM is configured for CPWM, TOF is set after the
counter has reached the value in the modulo register, at the transition to the next lower count value.
Clear TOF by reading the TPM status and control register when TOF is set and then writing a 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. Reset clears the TOF bit.
Writing a 1 to TOF has no effect.
1 = TPM counter has overflowed.
0 = TPM counter has not reached modulo value or overflow.
TOIE — Timer Overflow Interrupt Enable
This read/write bit enables TPM overflow interrupts. If TOIE is set, an interrupt is generated when
TOF equals 1. Reset clears TOIE.
1 = TOF interrupts enabled.
0 = TOF interrupts inhibited (use software polling).
CPWMS — Center-Aligned PWM Select
This read/write bit selects CPWM operating mode. Reset clears this bit so 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 the CPWMS bit.
1 = All TPMx channels operate in center-aligned PWM mode.
0 = All TPMx 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.
CLKSB:CLKSA — Clock Source Select
As shown in Table 10-1, this 2-bit field is used to disable the TPM system or select one of three clock
sources to drive the counter prescaler. The external source and the XCLK are synchronized to the bus
clock by an on-chip synchronization circuit.
Table 10-1. TPM Clock Source Selection
CLKSB:CLKSA
TPM Clock Source to Prescaler Input
0:0
No clock selected (TPM disabled)
0:1
Bus rate clock (BUSCLK)
1:0
Fixed system clock (XCLK)
1:1
External source (TPMx Ext Clk)1,2
1. The maximum frequency that is allowed as an external clock is one-fourth of the bus
frequency.
2. When the TPMxCH0 pin is selected as the TPM clock source, the corresponding
ELS0B:ELS0A control bits should be set to 0:0 so channel 0 does not try to use the same pin
for a conflicting function.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
161
Timer/PWM (TPM) Module
PS2:PS1:PS0 — Prescale Divisor Select
This 3-bit field selects one of eight divisors for the TPM clock input as shown in Table 10-2. This
prescaler is located after any clock source synchronization or clock source selection, so it affects
whatever clock source is selected to drive the TPM system.
Table 10-2. Prescale Divisor Selection
10.7.2
PS2:PS1:PS0
TPM Clock Source Divided-By
0:0:0
1
0:0:1
2
0:1:0
4
0:1:1
8
1:0:0
16
1:0:1
32
1:1:0
64
1:1:1
128
Timer x 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 byte is read. This allows coherent 16-bit reads in either order. The
coherency mechanism is automatically restarted by an MCU reset, a write of any value to TPMxCNTH or
TPMxCNTL, or any write to the timer status/control register (TPMxSC).
Reset clears the TPM counter registers.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
Write:
Reset:
Any write to TPMxCNTH clears the 16-bit counter.
0
0
0
0
0
0
Figure 10-6. Timer x Counter Register High (TPMxCNTH)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
Write:
Reset:
Any write to TPMxCNTL clears the 16-bit counter.
0
0
0
0
0
0
Figure 10-7. Timer x Counter Register Low (TPMxCNTL)
MC9S08GB/GT Data Sheet, Rev. 2.3
162
Freescale Semiconductor
TPM Registers and Control Bits
When background mode is active, the timer counter and the coherency mechanism are frozen such that the
buffer latches remain in the state they were in when the background mode became active even if one or
both bytes of the counter are read while background mode is active.
10.7.3
Timer x 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 $0000 at the next clock
(CPWMS = 0) or starts counting down (CPWMS = 1), 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 $0000, which results in a free-running timer
counter (modulo disabled).
Bit 7
6
5
4
3
3
2
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 10-8. Timer x Counter Modulo Register High (TPMxMODH)
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 10-9. Timer x Counter Modulo Register Low (TPMxMODL)
It is good practice to wait for an overflow interrupt so both bytes of the modulo register can be written well
before a new overflow. An alternative approach is to reset the TPM counter before writing to the TPM
modulo registers to avoid confusion about when the first counter overflow will occur.
10.7.4
Timer x Channel n Status and Control Register (TPMxCnSC)
TPMxCnSC contains the channel interrupt status flag and control bits that are used to configure the
interrupt enable, channel configuration, and pin function.
Bit 7
6
5
4
3
2
CHnF
CHnIE
MSnB
MSnA
ELSnB
ELSnA
0
0
0
0
0
0
Read:
1
Bit 0
0
0
0
0
Write:
Reset:
= Unimplemented or Reserved
Figure 10-10. Timer x Channel n Status and Control Register (TPMxCnSC)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
163
Timer/PWM (TPM) Module
CHnF — Channel n Flag
When channel n is configured for input capture, this flag bit is set when an active edge occurs on the
channel n pin. When channel n is an output compare or edge-aligned PWM channel, CHnF is set when
the value in the TPM counter registers matches the value in the TPM channel n value registers. This
flag is seldom used with center-aligned PWMs because it is set every time the counter matches the
channel value register, which correspond to both edges of the active duty cycle period.
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 0 to CHnF. If another interrupt
request occurs before the clearing sequence is complete, the sequence is reset so CHnF would remain
set after the clear sequence was completed for the earlier CHnF. This is done so a CHnF interrupt
request cannot be lost by clearing a previous CHnF.
Reset clears the CHnF bit. Writing a 1 to CHnF has no effect.
1 = Input capture or output compare event occurred on channel n.
0 = No input capture or output compare event occurred on channel n.
CHnIE — Channel n Interrupt Enable
This read/write bit enables interrupts from channel n. Reset clears the CHnIE bit.
1 = Channel n interrupt requests enabled.
0 = Channel n interrupt requests disabled (use software polling).
MSnB — Mode Select B for TPM Channel n
When CPWMS = 0, MSnB = 1 configures TPM channel n for edge-aligned PWM mode. For a
summary of channel mode and setup controls, refer to Table 10-3.
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 10-3 for a summary of channel mode and setup controls.
MC9S08GB/GT Data Sheet, Rev. 2.3
164
Freescale Semiconductor
TPM Registers and Control Bits
Table 10-3. Mode, Edge, and Level Selection
CPWMS
MSnB:MSnA
ELSnB:ELSnA
X
XX
00
Pin not used for TPM channel; use as an external clock for the TPM or
revert to general-purpose I/O
01
Capture on rising edge only
00
0
10
Input capture
Configuration
Capture on falling edge only
11
Capture on rising or falling edge
00
Software compare only
01
Toggle output on compare
01
Output compare
10
Clear output on compare
11
Set output on compare
10
Edge-aligned
PWM
1X
X1
10
1
Mode
Center-aligned
PWM
XX
X1
High-true pulses (clear output on compare)
Low-true pulses (set output on compare)
High-true pulses (clear output on compare-up)
Low-true pulses (set output on compare-up)
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. Typically, a program would clear
status flags after changing channel configuration bits and before enabling channel interrupts or using the
status flags to avoid any unexpected behavior.
ELSnB:ELSnA — Edge/Level Select Bits
Depending on the operating mode for the timer channel as set by CPWMS:MSnB:MSnA and shown
in Table 10-3, 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 unrelated
to any timer channel 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. This is also the setting
required for channel 0 when the TPMxCH0 pin is used as an external clock input.
10.7.5
Timer x 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 value registers are cleared
by reset.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
165
Timer/PWM (TPM) Module
Bit 7
6
5
4
3
2
1
Bit 0
Bit 15
14
13
12
11
10
9
Bit 8
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 10-11. Timer x Channel Value Register High (TPMxCnVH)
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 10-12. Timer x 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 byte is read. This latching mechanism also resets
(becomes unlatched) when the TPMxCnSC register is written.
In output compare or PWM modes, writing to either byte (TPMxCnVH or TPMxCnVL) latches the value
into a buffer. When both bytes have been written, they are transferred as a coherent 16-bit value into the
timer channel value registers. This latching mechanism may be manually reset by writing to the
TPMxCnSC register.
This latching mechanism allows coherent 16-bit writes in either order, which is friendly to various
compiler implementations.
MC9S08GB/GT Data Sheet, Rev. 2.3
166
Freescale Semiconductor
Chapter 11 Serial Communications Interface (SCI) Module
11.1
Introduction
The MC9S08GB/GT includes two independent serial communications interface (SCI) modules —
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, and 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
167
Chapter 11 Serial Communications Interface (SCI) Module
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when
KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 11-1. Block Diagram Highlighting the SCI Modules
MC9S08GB/GT Data Sheet, Rev. 2.3
168
Freescale Semiconductor
Features
11.2
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
• Hardware parity generation and checking
• Programmable 8-bit or 9-bit character length
• Receiver wakeup by idle-line or address-mark
11.3
SCI System 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.
11.4
Baud Rate Generation
As shown in Figure 11-2, the clock source for the SCI baud rate generator is the bus-rate clock.
MODULO DIVIDE BY
(1 THROUGH 8191)
BUSCLK
SBR12:SBR0
BAUD RATE GENERATOR
OFF IF [SBR12:SBR0] = 0
BAUD RATE =
DIVIDE BY
16
Tx BAUD RATE
Rx SAMPLING CLOCK
(16 × BAUD RATE)
BUSCLK
[SBR12:SBR0] × 16
Figure 11-2. 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
169
Serial Communications Interface (SCI) Module
The MC9S08GB/GT re-synchronizes 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 ±4.5 percent 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.
11.5
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.
11.5.1
Transmitter Block Diagram
Figure 11-3 shows the transmitter portion of the SCI.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
Transmitter Functional Description
INTERNAL BUS
(WRITE-ONLY)
LOOPS
SCID – Tx BUFFER
8
7
6
5
4
3
2
1
PT
PREAMBLE (ALL 1s)
PARITY
GENERATION
SHIFT ENABLE
PE
LOAD FROM SCIxD
SHIFT DIRECTION
T8
START
0
TO RECEIVE
DATA IN
TO TxD1 PIN
L
LSB
H
1 × BAUD
RATE CLOCK
11-BIT TRANSMIT SHIFT REGISTER
LOOP
CONTROL
BREAK (ALL 0s)
STOP
M
RSRC
SCI CONTROLS TxD1
TE
ENABLE
TRANSMIT CONTROL
SBK
TxD1 DIRECTION
TO TxD1
PIN LOGIC
TXDIR
TDRE
TIE
TC
Tx INTERRUPT
REQUEST
TCIE
Figure 11-3. SCI Transmitter Block Diagram
The transmitter is enabled by setting the TE bit in SCIxC2. This queues a preamble character that is one
full character frame of logic high. The transmitter then remains idle (TxD1 pin remains high) 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
171
Serial Communications Interface (SCI) Module
If no new character is waiting in the transmit data buffer after a stop bit is shifted out the TxD1 pin, the
transmitter sets the transmit complete flag and enters an idle mode, with TxD1 high, waiting for more
characters to transmit.
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.
11.5.2
Send Break and Queued Idle
The SBK control bit in SCIxC2 is used to send break characters that were originally used to gain the
attention of old teletype receivers. Break characters are a full character time of logic 0 (including a 0 where
the stop bit would be normally). 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 (or nine) data bits and a framing error (FE = 1).
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 TxD1 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 TxD1 is an output driving a logic 1. This ensures that the TxD1 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.
11.6
Receiver Functional Description
In this section, the receiver block diagram (Figure 11-4) 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.
11.6.1
Receiver Block Diagram
Figure 11-4 shows the receiver portion of the SCI.
MC9S08GB/GT Data Sheet, Rev. 2.3
172
Freescale Semiconductor
Receiver Functional Description
INTERNAL BUS
(READ-ONLY)
SCID – Rx BUFFER
16 × BAUD
RATE CLOCK
11-BIT RECEIVE SHIFT REGISTER
LOOPS
RSRC
SINGLE-WIRE
LOOP CONTROL
ALL 1s
WAKE
8
6
5
4
3
2
1
0
L
SHIFT DIRECTION
WAKEUP
LOGIC
ILT
7
MSB
H
DATA RECOVERY
FROM RxD1 PIN
START
M
LSB
STOP
DIVIDE
BY 16
RWU
FROM
TRANSMITTER
RDRF
RIE
IDLE
Rx INTERRUPT
REQUEST
ILIE
OR
ORIE
FE
FEIE
ERROR INTERRUPT
REQUEST
NF
NEIE
PE
PT
PARITY
CHECKING
PF
PEIE
Figure 11-4. SCI Receiver Block Diagram
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 11.8.1, “8- and 9-Bit Data Modes.” For the remainder of this discussion, we assume the SCI is
configured for normal 8-bit data mode.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
173
Serial Communications Interface (SCI) Module
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
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 11.7,
“Interrupts and Status Flags,” for more details about flag clearing.
11.6.2
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 RxD1 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 re-synchronized 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.
11.6.3
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 = 1, it
MC9S08GB/GT Data Sheet, Rev. 2.3
174
Freescale Semiconductor
Interrupts and Status Flags
inhibits setting of the status flags associated with the receiver, thus eliminating the software overhead for
handling the unimportant 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.
11.6.3.1 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). 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 doesn’t 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.
11.6.3.2 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).
11.7
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 and IDLE events, and a third vector is
used for OR, NF, FE, and PF error conditions. Each of these eight 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 TxD1 high. 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. 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. If the SCI is configured to operate in 9-bit mode, an additional read to the SCIxC3 register
is required to clear RDRF
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
175
Serial Communications Interface (SCI) Module
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 RxD1 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 and the data and any associated NF, FE, or PF
condition is lost.
11.8
Additional SCI Functions
The following sections describe additional SCI functions.
11.8.1
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.
When transmitting 9-bit data, write to the T8 bit before writing to SCIxD for coherent writes to the transmit
data buffer. 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.
When receiving 9-bit data, clear the RDRF bit by reading both R8 and SCIxD. R8 and SCIxD can be read
in either order.
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.
11.9
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
SCI Registers and Control Bits
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.
11.9.1
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 RxD1 pin is not used by the SCI, so it reverts to a
general-purpose port I/O pin.
11.9.2
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 TxD1 pin. The RxD1 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 TxD1 pin. When
TXDIR = 0, the TxD1 pin is an input to the SCI receiver and the transmitter is temporarily disconnected
from the TxD1 pin so an external device can send serial data to the receiver. When TXDIR = 1, the TxD1
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.
11.10 SCI Registers and Control Bits
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 section 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.
Some MCU systems have more than one SCI, so register names include placeholder characters to identify
which SCI is being referenced. For example, SCIxC1 refers to the SCIx control register 1 and SCI2C1 is
the control register 1 for SCI2.
11.10.1 SCI x 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).
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
177
Serial Communications Interface (SCI) Module
Read:
Bit 7
6
5
0
0
0
4
3
2
1
Bit 0
SBR12
SBR11
SBR10
SBR9
SBR8
0
0
0
0
0
Write:
Reset:
0
0
0
= Unimplemented or Reserved
Figure 11-5. SCI Baud Rate Register (SCIxBDH)
Bit 7
6
5
4
3
2
1
Bit 0
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
0
0
0
0
0
1
0
0
Read:
Write:
Reset:
= Unimplemented or Reserved
Figure 11-6. SCI x Baud Rate Register (SCIxBDL)
SBR12:SBR0 — Baud Rate Modulo Divisor
These 13 bits 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).
11.10.2 SCI x Control Register 1 (SCIxC1)
This read/write register is used to control various optional features of the SCI system.
Bit 7
6
5
4
3
2
1
Bit 0
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 11-7. SCI x Control Register 1 (SCIxC1)
LOOPS — 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.
1 = Loop mode or single-wire mode where transmitter outputs are internally connected to receiver
input. (See RSRC bit.) RxD1 pin is not used by SCI.
0 = Normal operation — RxD1 and TxD1 use separate pins.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
SCI Registers and Control Bits
SCISWAI — SCI Stops in Wait Mode
1 = SCI clocks freeze while CPU is 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.
RSRC — 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 TxD1 pin and RSRC determines whether this connection is also
connected to the transmitter output.
1 = Single-wire SCI mode where the TxD1 pin is connected to the transmitter output and receiver
input.
0 = Provided LOOPS = 1, RSRC = 0 selects internal loop back mode and the SCI does not use the
RxD1 or TxD1 pins.
M — 9-Bit or 8-Bit Mode Select
1 = Receiver and transmitter use 9-bit data characters
start + 8 data bits (LSB first) + 9th data bit + stop.
0 = Normal — start + 8 data bits (LSB first) + stop.
WAKE — Receiver Wakeup Method Select
Refer to Section 11.6.3, “Receiver Wakeup Operation,” for more information.
1 = Address-mark wakeup.
0 = Idle-line wakeup.
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 the logic high level by the idle line detection logic. Refer to Section 11.6.3.1,
“Idle-Line Wakeup,” for more information.
1 = Idle character bit count starts after stop bit.
0 = Idle character bit count starts after start bit.
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.
1 = Parity enabled.
0 = No hardware parity generation or checking.
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.
1 = Odd parity.
0 = Even parity.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
179
Serial Communications Interface (SCI) Module
11.10.3 SCI x Control Register 2 (SCIxC2)
This register can be read or written at any time.
Bit 7
6
5
4
3
2
1
Bit 0
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 11-8. SCI x Control Register 2 (SCIxC2)
TIE — Transmit Interrupt Enable (for TDRE)
1 = Hardware interrupt requested when TDRE flag is 1.
0 = Hardware interrupts from TDRE disabled (use polling).
TCIE — Transmission Complete Interrupt Enable (for TC)
1 = Hardware interrupt requested when TC flag is 1.
0 = Hardware interrupts from TC disabled (use polling).
RIE — Receiver Interrupt Enable (for RDRF)
1 = Hardware interrupt requested when RDRF flag is 1.
0 = Hardware interrupts from RDRF disabled (use polling).
ILIE — Idle Line Interrupt Enable (for IDLE)
1 = Hardware interrupt requested when IDLE flag is 1.
0 = Hardware interrupts from IDLE disabled (use polling).
TE — Transmitter Enable
1 = Transmitter on.
0 = Transmitter off.
TE must be 1 in order to use the SCI transmitter. Normally, when TE = 1, the SCI forces the TxD1 pin
to act as an output for the SCI system. If LOOPS = 1 and RSRC = 0, the TxD1 pin reverts to being a
port B general-purpose I/O pin even if TE = 1.
When the SCI is configured for single-wire operation (LOOPS = RSRC = 1), TXDIR controls the
direction of traffic on the single SCI communication line (TxD1 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 11.5.2, “Send Break and Queued Idle,” for more details.
When TE is written to 0, the transmitter keeps control of the port TxD1 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
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Freescale Semiconductor
SCI Registers and Control Bits
RE — Receiver Enable
When the SCI receiver is off, the RxD1 pin reverts to being a general-purpose port I/O pin.
1 = Receiver on.
0 = Receiver off.
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 11.6.3, “Receiver Wakeup
Operation,” for more details.
1 = SCI receiver in standby waiting for wakeup condition.
0 = Normal SCI receiver operation.
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 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 11.5.2, “Send Break and
Queued Idle,” for more details.
1 = Queue break character(s) to be sent.
0 = Normal transmitter operation.
11.10.4 SCI x Status Register 1 (SCIxS1)
This register has eight read-only status flags. Writes have no effect. Special software sequences (that do
not involve writing to this register) are used to clear these status flags.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
1
1
0
0
0
0
0
0
Write:
Reset:
= Unimplemented or Reserved
Figure 11-9. SCI x Status Register 1 (SCIxS1)
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).
1 = Transmit data register (buffer) empty.
0 = Transmit data register (buffer) full.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
181
Serial Communications Interface (SCI) Module
TC — Transmission Complete Flag
TC is set out of reset and when TDRE = 1 and no data, preamble, or break character is being
transmitted.
1 = Transmitter idle (transmission activity complete).
0 = Transmitter active (sending data, a preamble, or a break).
TC is cleared automatically by reading SCIxS1 with TC = 1 and then doing one of the following:
— 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
RDRF — Receive Data Register Full Flag
RDRF becomes set when a character transfers from the receive shifter into the receive data register
(SCIxD). In 8-bit mode, to clear RDRF, read SCIxS1 with RDRF = 1 and then read the SCI data
register (SCIxD). In 9-bit mode, to clear RDRF, read SCIxS1 with RDRF = 1 and then read SCIxD
and the SCI control 3 register (SCIxC3). SCIxD and SCIxC3 can be read in any order, but the flag is
cleared only after both data registers are read.
1 = Receive data register full.
0 = Receive data register empty.
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 be set only once even if the receive line remains idle for an extended period.
1 = Idle line was detected.
0 = No idle line detected.
MC9S08GB/GT Data Sheet, Rev. 2.3
182
Freescale Semiconductor
SCI Registers and Control Bits
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).
1 = Receive overrun (new SCI data lost).
0 = No overrun.
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).
1 = Noise detected in the received character in SCIxD.
0 = No noise detected.
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).
1 = Framing error.
0 = No framing error detected. This does not guarantee the framing is correct.
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).
1 = Parity error.
0 = No parity error.
11.10.5 SCI x Status Register 2 (SCIxS2)
This register has one read-only status flag. Writes have no effect.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
RAF
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented or Reserved
Figure 11-10. SCI x Status Register 2 (SCIxS2)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
183
Serial Communications Interface (SCI) Module
RAF — 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.
1 = SCI receiver active (RxD1 input not idle).
0 = SCI receiver idle waiting for a start bit.
11.10.6 SCI x Control Register 3 (SCIxC3)
Bit 7
Read:
6
5
T8
TXDIR
0
0
R8
4
3
2
1
Bit 0
ORIE
NEIE
FEIE
PEIE
0
0
0
0
0
Write:
Reset:
0
0
= Unimplemented or Reserved
Figure 11-11. SCI x Control Register 3 (SCIxC3)
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, both R8 and
SCIxD must be read to complete the automatic RDRF clearing sequence.
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.
TXDIR — TxD1 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 TxD1 pin.
1 = TxD1 pin is an output in single-wire mode.
0 = TxD1 pin is an input in single-wire mode.
ORIE — Overrun Interrupt Enable
This bit enables the overrun flag (OR) to generate hardware interrupt requests.
1 = Hardware interrupt requested when OR = 1.
0 = OR interrupts disabled (use polling).
MC9S08GB/GT Data Sheet, Rev. 2.3
184
Freescale Semiconductor
SCI Registers and Control Bits
NEIE — Noise Error Interrupt Enable
This bit enables the noise flag (NF) to generate hardware interrupt requests.
1 = Hardware interrupt requested when NF = 1.
0 = NF interrupts disabled (use polling).
FEIE — Framing Error Interrupt Enable
This bit enables the framing error flag (FE) to generate hardware interrupt requests.
1 = Hardware interrupt requested when FE = 1.
0 = FE interrupts disabled (use polling).
PEIE — Parity Error Interrupt Enable
This bit enables the parity error flag (PF) to generate hardware interrupt requests.
1 = Hardware interrupt requested when PF = 1.
0 = PF interrupts disabled (use polling).
11.10.7 SCI x 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.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
R7
R6
R5
R4
R3
R2
R1
R0
Write:
T7
T6
T5
T4
T3
T2
T1
T0
Reset:
0
0
0
0
0
0
0
0
Figure 11-12. SCI x Data Register (SCIxD)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
185
Serial Communications Interface (SCI) Module
MC9S08GB/GT Data Sheet, Rev. 2.3
186
Freescale Semiconductor
Chapter 12 Serial Peripheral Interface (SPI) Module
The MC9S08GB/GT provides one serial peripheral interface (SPI) module. The four pins associated with
SPI functionality are shared with port E pins 2–5. See the Appendix A, “Electrical Characteristics,”
appendix for SPI electrical parametric information. When the SPI is enabled, the direction of pins is
controlled by module configuration. If the SPI is disabled, all four pins can be used as general-purpose I/O.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
187
Chapter 12 Serial Peripheral Interface (SPI) Module
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when
KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 12-1. Block Diagram Highlighting the SPI Module
MC9S08GB/GT Data Sheet, Rev. 2.3
188
Freescale Semiconductor
Features
12.1
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
12.2
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.
12.2.1
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 MOSI1 pin) to
the slave while simultaneously shifting data in (on the MISO1 pin) from the slave. The transfer effectively
exchanges the data that was in the SPI shift registers of the two SPI systems. The SPSCK1 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 (SS1 pin). In this system, the master device has configured its SS1 pin as an optional
slave select output.
SLAVE
MASTER
MOSI1
MOSI1
SPI SHIFTER
7
6
5
4
3
2
SPI SHIFTER
1
0
MISO1
SPSCK1
CLOCK
GENERATOR
SS1
MISO1
7
6
5
4
3
2
1
0
SPSCK1
SS1
Figure 12-2. SPI System Connections
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
189
Serial Peripheral Interface (SPI) Module
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.
12.2.2
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 SPSCK1 pin, the shifter output is
routed to MOSI1, and the shifter input is routed from the MISO1 pin.
When the SPI is configured as a slave, the SPSCK1 pin is routed to the clock input of the SPI, the shifter
output is routed to MISO1, and the shifter input is routed from the MOSI1 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
190
Freescale Semiconductor
Block Diagrams
PIN CONTROL
M
SPE
MOSI1
(MOMI)
S
Tx BUFFER (WRITE SPI1D)
ENABLE
SPI SYSTEM
M
SHIFT
OUT
SPI SHIFT REGISTER
SHIFT
IN
MISO1
(SISO)
S
SPC0
Rx BUFFER (READ SPI1D)
BIDIROE
SHIFT
DIRECTION
LSBFE
SHIFT
CLOCK
Rx BUFFER
FULL
Tx BUFFER
EMPTY
MASTER CLOCK
BUS RATE
CLOCK
MSTR
SPIBR
CLOCK GENERATOR
CLOCK
LOGIC
SLAVE CLOCK
MASTER/SLAVE
M
SPSCK1
S
MASTER/
SLAVE
MODE SELECT
MODFEN
SSOE
MODE FAULT
DETECTION
SS1
SPRF
SPTEF
SPTIE
MODF
SPIE
SPI
INTERRUPT
REQUEST
Figure 12-3. SPI Module Block Diagram
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
191
Serial Peripheral Interface (SPI) Module
12.2.3
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.
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
12.3
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 MISO1 pin at one SPSCK edge and shifted, changing
the bit value on the MOSI1 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 MOSI1 pin to the slave while eight bits of data
were shifted in the MISO1 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 SS1 pin must be driven low before a transfer starts and SS1 must
stay low throughout the transfer. If a clock format where CPHA = 0 is selected, SS1 must be driven to a
logic 1 between successive transfers. If CPHA = 1, SS1 may remain low between successive transfers. See
Section 12.3.1, “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.
MC9S08GB/GT Data Sheet, Rev. 2.3
192
Freescale Semiconductor
Functional Description
12.3.1
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 12-5 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 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 12-5. SPI Clock Formats (CPHA = 1)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
193
Serial Peripheral Interface (SPI) Module
When CPHA = 1, the slave begins to drive its MISO output when SS1 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 12-6 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 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 12-6. SPI Clock Formats (CPHA = 0)
MC9S08GB/GT Data Sheet, Rev. 2.3
194
Freescale Semiconductor
Functional Description
When CPHA = 0, the slave begins to drive its MISO output with the first data bit value (MSB or LSB
depending on LSBFE) when SS1 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.
12.3.2
SPI Pin Controls
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.
12.3.2.1 SPSCK1 — 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.
12.3.2.2 MOSI1 — 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.
12.3.2.3 MISO1 — 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.
12.3.2.4 SS1 — 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).
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
195
Serial Peripheral Interface (SPI) Module
12.3.3
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).
12.3.4
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 SS1 pin (provided the SS1 pin is configured as the mode fault input signal). The SS1 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 SS1 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 SPSCK1, MOSI1, and MISO1 (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.
12.4
SPI Registers and Control Bits
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
196
Freescale Semiconductor
SPI Registers and Control Bits
12.4.1
SPI Control Register 1 (SPI1C1)
This read/write register includes the SPI enable control, interrupt enables, and configuration options.
Bit 7
6
5
4
3
2
1
Bit 0
SPIE
SPE
SPTIE
MSTR
CPOL
CPHA
SSOE
LSBFE
0
0
0
0
0
1
0
0
Read:
Write:
Reset:
Figure 12-7. SPI Control Register 1 (SPI1C1)
SPIE — SPI Interrupt Enable (for SPRF and MODF)
This is the interrupt enable for SPI receive buffer full (SPRF) and mode fault (MODF) events.
1 = When SPRF or MODF is 1, request a hardware interrupt.
0 = Interrupts from SPRF and MODF inhibited (use polling).
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.
1 = SPI system enabled.
0 = SPI system inactive.
SPTIE — SPI Transmit Interrupt Enable
This is the interrupt enable bit for SPI transmit buffer empty (SPTEF).
1 = When SPTEF is 1, hardware interrupt requested.
0 = Interrupts from SPTEF inhibited (use polling).
MSTR — Master/Slave Mode Select
1 = SPI module configured as a master SPI device.
0 = SPI module configured as a slave SPI device.
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 12.3.1, “SPI Clock Formats,” for more details.
1 = Active-low SPI clock (idles high).
0 = Active-high SPI clock (idles low).
CPHA — Clock Phase
This bit selects one of two clock formats for different kinds of synchronous serial peripheral devices.
Refer to Section 12.3.1, “SPI Clock Formats,” for more details.
1 = First edge on SPSCK occurs at the start of the first cycle of an 8-cycle data transfer.
0 = First edge on SPSCK occurs at the middle of the first cycle of an 8-cycle data transfer.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
197
Serial Peripheral Interface (SPI) Module
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 SS1 pin as shown in Table 12-1.
Table 12-1. SS1 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
LSBFE — LSB First (Shifter Direction)
1 = SPI serial data transfers start with least significant bit.
0 = SPI serial data transfers start with most significant bit.
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.
Read:
Bit 7
6
5
0
0
0
4
3
2
1
Bit 0
SPISWAI
SPC0
0
0
0
MODFEN BIDIROE
Write:
Reset:
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 12-8. SPI Control Register 2 (SPI1C2)
MODFEN — Master Mode-Fault Function Enable
When the SPI is configured for slave mode, this bit has no meaning or effect. (The SS1 pin is the slave
select input.) In master mode, this bit determines how the SS1 pin is used (refer to Table 12-1 for more
details).
1 = Mode fault function enabled, master SS1 pin acts as the mode fault input or the slave select
output.
0 = Mode fault function disabled, master SS1 pin reverts to general-purpose I/O not controlled by
SPI.
MC9S08GB/GT Data Sheet, Rev. 2.3
198
Freescale Semiconductor
SPI Registers and Control Bits
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 MOSI1 (MOMI) or MISO1 (SISO) pin,
respectively, as the single SPI data I/O pin. When SPC0 = 0, BIDIROE has no meaning or effect.
1 = SPI I/O pin enabled as an output.
0 = Output driver disabled so SPI data I/O pin acts as an input.
SPISWAI — SPI Stop in Wait Mode
1 = SPI clocks stop when the MCU enters wait mode.
0 = SPI clocks continue to operate in wait mode.
SPC0 — SPI Pin Control 0
The SPC0 bit chooses single-wire bidirectional mode. If MSTR = 0 (slave mode), the SPI uses the
MISO1 (SISO) pin for bidirectional SPI data transfers. If MSTR = 1 (master mode), the SPI uses the
MOSI1 (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.
1 = SPI configured for single-wire bidirectional operation.
0 = SPI uses separate pins for data input and data output.
12.4.3
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.
Bit 7
Read:
6
5
4
SPPR2
SPPR1
SPPR0
0
0
0
0
3
2
1
Bit 0
SPR2
SPR1
SPR0
0
0
0
0
Write:
Reset:
0
0
= Unimplemented or Reserved
Figure 12-9. SPI Baud Rate Register (SPI1BR)
SPPR2:SPPR1:SPPR0 — SPI Baud Rate Prescale Divisor
This 3-bit field selects one of eight divisors for the SPI baud rate prescaler as shown in Table 12-2. 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).
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
199
Serial Peripheral Interface (SPI) Module
Table 12-2. 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
SPR2:SPR1:SPR0 — SPI Baud Rate Divisor
This 3-bit field selects one of eight divisors for the SPI baud rate divider as shown in Figure 12-3. 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.
Table 12-3. SPI Baud Rate Divisor
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
MC9S08GB/GT Data Sheet, Rev. 2.3
200
Freescale Semiconductor
SPI Registers and Control Bits
12.4.4
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 0s.
Writes have no meaning or effect.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
SPRF
0
SPTEF
MODF
0
0
0
0
0
0
1
0
0
0
0
0
Write:
Reset:
= Unimplemented or Reserved
Figure 12-10. SPI Status Register (SPI1S)
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.
1 = Data available in the receive data buffer.
0 = No data available in the receive data buffer.
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.
1 = SPI transmit buffer empty.
0 = SPI transmit buffer not empty.
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 SS1 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).
1 = Mode fault error detected.
0 = No mode fault error.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
201
Serial Peripheral Interface (SPI) Module
12.4.5
SPI Data Register (SPI1D)
Bit 7
6
5
4
3
2
1
Bit 0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 12-11. 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
202
Freescale Semiconductor
Chapter 13 Inter-Integrated Circuit (IIC) Module
The MC9S08GB/GT series of microcontrollers provides one inter-integrated circuit (IIC) module for
communication with other integrated circuits. The two pins associated with this module, SDA1 and SCL1
share port C pins 2 and 3, respectively. All functionality as described in this section is available on
MC9S08GB/GT. When the IIC is enabled, the direction of pins is controlled by module configuration. If
the IIC is disabled, both pins can be used as general-purpose I/O.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
203
Chapter 13 Inter-Integrated Circuit (IIC) Module
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available
when KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 13-1. Block Diagram Highlighting the IIC Module
MC9S08GB/GT Data Sheet, Rev. 2.3
204
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
13.1
Introduction
The inter-integrated circuit (IIC) provides a method of communication between a number of devices. The
interface is designed to operate up to 100 kbps with maximum bus loading and timing. The device is
capable of operating at higher baud rates, up to a maximum of clock/20, with reduced bus loading. The
maximum communication length and the number of devices that can be connected are limited by a
maximum bus capacitance of 400 pF.
For additional detail, please refer to volume 1 of the HCS08 Reference Manual, (Freescale Semiconductor
document order number HCS08RMv1/D).
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
13.1.2
Modes of Operation
The IIC functions the same in normal and monitor modes. 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 will continue 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. Stop1 and stop2 will reset the register contents.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
205
Inter-Integrated Circuit (IIC) Module
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
13.1.4
Detailed Signal Descriptions
This section describes each user-accessible pin signal.
13.1.4.1
SCL1 — Serial Clock Line
The bidirectional SCL1 is the serial clock line of the IIC system.
13.1.4.2
SDA1 — Serial Data Line
The bidirectional SDA1 is the serial data line of the IIC system
MC9S08GB/GT Data Sheet, Rev. 2.3
206
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
13.2
Functional Description
This section provides a complete functional description of the IIC module.
13.2.1
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 13-3.
MSB
SCL
SDA
1
LSB
2
3
4
5
6
7
CALLING ADDRESS
1
XXX
3
4
5
CALLING ADDRESS
2
3
4
5
6
7
8
D7
D6
D5
D4
D3
D2
D1
D0
6
7
8
9
READ/ ACK
WRITE BIT
1
XX
9
NO STOP
ACK SIGNAL
BIT
MSB
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
START
SIGNAL
1
DATA BYTE
LSB
2
LSB
READ/ ACK
WRITE BIT
MSB
SDA
9
AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W
START
SIGNAL
SCL
8
MSB
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/ NO STOP
SIGNAL
WRITE ACK
BIT
Figure 13-3. IIC Bus Transmission Signals
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
207
Inter-Integrated Circuit (IIC) Module
13.2.1.1
START Signal
When the bus is free; i.e., no master device is engaging the bus (both SCL and SDA lines are at logical
high), a master may initiate communication by sending a START signal. As shown in Figure 13-3, 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.
13.2.1.2
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 will respond by
sending back an acknowledge bit. This is done by pulling the SDA low at the 9th clock (see Figure 13-3).
No two slaves in the system may have the same address. If the IIC module is the master, it must not transmit
an address that is 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 will revert to slave mode and operate
correctly even if it is being addressed by another master.
13.2.1.3
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 13-3. 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 9th 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
208
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
13.2.1.4
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 13-3).
The master can generate a STOP even if the slave has generated an acknowledge at which point the slave
must release the bus.
13.2.1.5
Repeated START Signal
As shown in Figure 13-3, 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.
13.2.1.6
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,
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.
13.2.1.7
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 13-4). 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
209
Inter-Integrated Circuit (IIC) Module
DELAY
START COUNTING HIGH PERIOD
SCL1
SCL2
SCL
INTERNAL COUNTER RESET
Figure 13-4. IIC Clock Synchronization
13.2.1.8
Handshaking
The clock synchronization mechanism can be used as a handshake in data transfer. Slave devices may hold
the SCL low after completion of one byte transfer (9 bits). In such case, it halts the bus clock and forces
the master clock into wait states until the slave releases the SCL line.
13.2.1.9
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.
13.3
Resets
The IIC is disabled after reset. The IIC cannot cause an MCU reset.
MC9S08GB/GT Data Sheet, Rev. 2.3
210
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
13.4
Interrupts
The IIC generates a single interrupt.
An interrupt from the IIC is generated when any of the events in Table 13-1 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 one to it in the interrupt routine.
The user can determine the interrupt type by reading the status register.
Table 13-1. Interrupt Summary
Interrupt Source
13.4.1
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 9th clock to indicate the completion of
byte transfer.
13.4.2
Address Detect Interrupt
When its own specific address (IIC address register) is matched with the calling address, the IAAS bit in
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.
13.4.3
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.
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 by writing a one to it.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
211
Inter-Integrated Circuit (IIC) Module
13.5
IIC Registers and Control Bits
This section consists of the IIC register descriptions in address order.
Refer to the direct-page register summary in the Memory chapter of this data sheet 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.
13.5.1
IIC Address Register (IIC1A)
Bit 7
6
5
4
3
2
1
Read:
Bit 0
0
ADDR
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 13-5. IIC Address Register (IIC1A)
ADDR — IIC Address Register
The ADDR contains the specific slave address to be used by the IIC module. This is the address the
module will respond to when addressed as a slave.
13.5.2
IIC Frequency Divider Register (IIC1F)
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
Read:
MULT
ICR
Write:
Reset:
0
0
0
0
0
Figure 13-6. IIC Frequency Divider Register (IIC1F)
MULT — IIC Multiplier Factor
The MULT bits define the multiplier factor mul. This factor is used along with the SCL divider to
generate the IIC baud rate. Table 13-2 provides the multiplier factor mul as defined by the MULT bits.
Table 13-2. Multiplier Factor
MULT
mul
00
01
01
02
10
04
11
Reserved
MC9S08GB/GT Data Sheet, Rev. 2.3
212
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
ICR — IIC Clock Rate
The ICR bits are used to prescale the bus clock for bit rate selection. These bits are used to define the
SCL divider and the SDA hold value. The SCL divider multiplied by the value provided by the MULT
register (multiplier factor mul) is used to generate IIC baud rate.
IIC baud rate = bus speed (Hz)/(mul * SCL divider)
SDA hold time is the delay from the falling edge of the SCL (IIC clock) to the changing of SDA (IIC
data). The ICR is used to determine the SDA hold value.
SDA hold time = bus period (s) * SDA hold value
Table 13-3 provides the SCL divider and SDA hold values for corresponding values of the ICR. These
values can be used to set IIC baud rate and SDA hold time. For example:
Bus speed = 8 MHz
MULT is set to 01 (mul = 2)
Desired IIC baud rate = 100 kbps
IIC baud rate = bus speed (Hz)/(mul * SCL divider)
100000 = 8000000/(2*SCL divider)
SCL divider = 40
Table 13-3 shows that ICR must be set to 0B to provide an SCL divider of 40 and that this will result
in an SDA hold value of 9.
SDA hold time = bus period (s) * SDA hold value
SDA hold time = 1/8000000 * 9 = 1.125 µs
If the generated SDA hold value is not acceptable, the MULT bits can be used to change the ICR. This
will result in a different SDA hold value.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
213
Inter-Integrated Circuit (IIC) Module
Table 13-3. IIC Divider and Hold Values
ICR
(hex)
SCL Divider
SDA Hold
Value
ICR
(hex)
SCL Divider
SDA Hold
Value
00
20
7
20
160
17
01
22
7
21
192
17
02
24
8
22
224
33
03
26
8
23
256
33
04
28
9
24
288
49
05
30
9
25
320
49
06
34
10
26
384
65
07
40
10
27
480
65
08
28
7
28
320
33
09
32
7
29
384
33
0A
36
9
2A
448
65
0B
40
9
2B
512
65
0C
44
11
2C
576
97
0D
48
11
2D
640
97
0E
56
13
2E
768
129
0F
68
13
2F
960
129
10
48
9
30
640
65
11
56
9
31
768
65
12
64
13
32
896
129
13
72
13
33
1024
129
14
80
17
34
1152
193
15
88
17
35
1280
193
16
104
21
36
1536
257
17
128
21
37
1920
257
18
80
9
38
1280
129
19
96
9
39
1536
129
1A
112
17
3A
1792
257
1B
128
17
3B
2048
257
1C
144
25
3C
2304
385
1D
160
25
3D
2560
385
1E
192
33
3E
3072
513
1F
240
33
3F
3840
513
MC9S08GB/GT Data Sheet, Rev. 2.3
214
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
13.5.3
IIC Control Register (IIC1C)
Bit 7
6
5
4
3
IICEN
IICIE
MST
TX
TXAK
Read:
Write:
Reset:
2
1
Bit 0
0
0
0
0
0
RSTA
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 13-7. IIC Control Register (IIC1C)
IICEN — IIC Enable
The IICEN bit determines whether the IIC module is enabled.
1 = IIC is enabled.
0 = IIC is not enabled.
IICIE — IIC Interrupt Enable
The IICIE bit determines whether an IIC interrupt is requested.
1 = IIC interrupt request enabled.
0 = IIC interrupt request not enabled.
MST — Master Mode Select
The MST bit is changed 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.
1 = Master Mode.
0 = Slave Mode.
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 will always be high.
When addressed as a slave this bit should be set by software according to the SRW bit in the status
register.
1 = Transmit.
0 = Receive.
TXAK — Transmit Acknowledge Enable
This bit specifies the value driven onto the SDA during data acknowledge cycles for both master and
slave receivers.
1 = No acknowledge signal response is sent.
0 = An acknowledge signal will be sent out to the bus after receiving one data byte.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
215
Inter-Integrated Circuit (IIC) Module
RSTA — Repeat START
Writing a one to this bit will generate a repeated START condition provided it is the current master.
This bit will always be read as a low. Attempting a repeat at the wrong time will result in loss of
arbitration.
13.5.4
IIC Status Register (IIC1S)
Bit 7
Read:
6
TCF
5
4
BUSY
IAAS
3
2
0
SRW
ARBL
1
Bit 0
RXAK
IICIF
Write:
Reset:
1
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 13-8. IIC Status Register (IIC1S)
TCF — Transfer Complete Flag
This bit is set on the completion of a byte transfer. Note that this bit is only valid during or immediately
following a transfer to the IIC module or from the IIC module.The TCF bit is cleared by reading the
IIC1D register in receive mode or writing to the IIC1D in transmit mode.
1 = Transfer complete.
0 = Transfer in progress.
IAAS — Addressed as a Slave
The IAAS bit is set when its own specific address is matched with the calling address. Writing the
IIC1C register clears this bit.
1 = Addressed as a slave.
0 = Not addressed.
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.
1 = Bus is busy.
0 = Bus is idle.
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 one to it.
1 = Loss of arbitration.
0 = Standard bus operation.
MC9S08GB/GT Data Sheet, Rev. 2.3
216
Freescale Semiconductor
Inter-Integrated Circuit (IIC) Module
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.
1 = Slave transmit, master reading from slave.
0 = Slave receive, master writing to slave.
IICIF — IIC Interrupt Flag
The IICIF bit is set when an interrupt is pending. This bit must be cleared by software, by writing a
one 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
1 = Interrupt pending.
0 = No interrupt pending.
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.
1 = No acknowledge received.
0 = Acknowledge received.
13.5.5
IIC Data I/O Register (IIC1D)
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
Read:
DATA
Write:
Reset:
0
0
0
0
Figure 13-9. IIC Data I/O Register (IIC1D)
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
217
Inter-Integrated Circuit (IIC) Module
Note that 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, then reading the IIC1D will not initiate the receive.
Reading the IIC1D will return the last byte received while the IIC is configured in either master receive
or slave receive modes. The IIC1D does not reflect every byte that is 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–bit 1) concatenated with the
required R/W bit (in position bit 0).
MC9S08GB/GT Data Sheet, Rev. 2.3
218
Freescale Semiconductor
Chapter 14 Analog-to-Digital Converter (ATD) Module
The MC9S08GB/GT provides one 8-channel analog-to-digital (ATD) module. The eight ATD channels
share port B. Each channel individually can be configured for general-purpose I/O or for ATD
functionality. All features of the ATD module as described in this section are available on the
MC9S08GB/GT. Electrical parametric information for the ATD may be found in Appendix A, “Electrical
Characteristics.”
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
219
Chapter 14 Analog-to-Digital Converter (ATD) Module
RTI
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD1)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VDD
VSS
VOLTAGE
REGULATOR
NOTES:
1. Port pins are software configurable with pullup device if input port.
2. Pin contains software configurable pullup/pulldown device if IRQ enabled
(IRQPE = 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. High current drive
6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown
available when KBI enabled (KBIPn = 1).
PORT B
PTB7/AD1P7–
PTB0/AD1P0
NOTE 1
PTE7
PTE6
PTE5/SPSCK1
PTE4/MOSI1
PTE3/MISO1
PTE2/SS1
PTE1/RxD1
PTE0/TxD1
NOTE 1
PTF7–PTF0
NOTES 1, 5
SERIAL PERIPHERAL
INTERFACE MODULE (SPI1)
LOW-POWER OSCILLATOR
NOTES 1, 6
PTD7/TPM2CH4
PTD6/TPM2CH3
PTD5/TPM2CH2
PTD4/TPM2CH1
PTD3/TPM2CH0
PTD2/TPM1CH2
PTD1/TPM1CH1
PTD0/TPM1CH0
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTA7/KBI1P7–
PTA0/KBI1P0
PTC7
PTC6
PTC5
PTC4
PTC3/SCL1
PTC2/SDA1
PTC1/RxD2
PTC0/TxD2
PORT F
USER FLASH
(GB60 = 61,268 BYTES)
(GB32 = 32,768 BYTES)
VDDAD
VSSAD
VREFH
VREFL
8
IIC MODULE (IIC1)
PORT G
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
8-BIT KEYBOARD
INTERRUPT MODULE (KBI1)
8
PORT C
HCS08 SYSTEM CONTROL
RESET
NOTE 4
DEBUG
MODULE (DBG)
PORT D
CPU
PORT E
BDC
PORT A
INTERNAL BUS
HCS08 CORE
NOTES 1, 5
NOTE 1
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTE 1
Figure 14-1. MC9S08GBxx Block Diagram Highlighting ATD Block and Pins
MC9S08GB/GT Data Sheet, Rev. 2.3
220
Freescale Semiconductor
Introduction
14.1
Introduction
The ATD module is an analog-to-digital converter with a successive approximation register (SAR)
architecture with sample and hold.
14.1.1
•
•
•
•
•
•
•
Features
8-/10-bit resolution
14.0 µsec, 10-bit single conversion time at a conversion frequency of 2 MHz
Left-/right-justified result data
Left-justified signed data mode
Conversion complete flag or conversion complete interrupt generation
Analog input multiplexer for up to eight analog input channels
Single or continuous conversion mode
14.1.2
Modes of Operation
The ATD has two modes for low power
• Stop mode
• Power-down mode
14.1.2.1 Stop Mode
When the MCU goes into stop mode, the MCU stops the clocks and the ATD analog circuitry is turned off,
placing the module into a low-power state. Once in stop mode, the ATD module aborts any single or
continuous conversion in progress. Upon exiting stop mode, no conversions occur and the registers have
their previous values. As long as the ATDPU bit is set prior to entering stop mode, the module is reactivated
coming out of stop.
14.1.2.2 Power Down Mode
Clearing the ATDPU bit in register ATD1C also places the ATD module in a low-power state. The ATD
conversion clock is disabled and the analog circuitry is turned off, placing the module in power-down
mode. (This mode does not remove power to the ATD module.) Once in power-down mode, the ATD
module aborts any conversion in progress. Upon setting the ATDPU bit, the module is reactivated. During
power-down mode, the ATD registers are still accessible.
Note that the reset state of the ATDPU bit is zero. Therefore, the module is reset into the power-down state.
14.1.3
Block Diagram
Figure 14-2 illustrates the functional structure of the ATD module.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
221
Analog-to-Digital Converter (ATD) Module
CONTROL
INTERRUPT
DATA
JUSTIFICATION
CONTROL AND
STATUS
REGISTERS
ADDRESS
R/W DATA
RESULT REGISTERS
SAR_REG
<9:0>
CTL
VDD
STATUS
PRESCALER
VSS
CTL
BUSCLK
CONVERSION MODE
CLOCK
PRESCALER
CONTROL BLOCK
STATE
MACHINE
CONVERSION CLOCK
DIGITAL
ANALOG
CTL
POWERDOWN
VREFH
VREFL
VSSAD
SUCCESSIVE APPROXIMATION REGISTER
ANALOG-TO-DIGITAL CONVERTER (ATD) BLOCK
AD1P0
AD1P1
AD1P2
AD1P3
AD1P4
CONVERSION REGISTER
VDDAD
INPUT
MUX
AD1P5
AD1P6
AD1P7
= INTERNAL PINS
= CHIP PADS
Figure 14-2. ATD Block Diagram
14.2
14.2.1
Signal Description
Overview
The ATD supports eight input channels and requires 4 supply/reference/ground pins. These pins are listed
in Table 14-1.
MC9S08GB/GT Data Sheet, Rev. 2.3
222
Freescale Semiconductor
Functional Description
Table 14-1. Signal Properties
Name
Function
AD7–AD0
Channel input pins
VREFH
High reference voltage for ATD converter
VREFL
Low reference voltage for ATD converter
VDDAD
ATD power supply voltage
VSSAD
ATD ground supply voltage
14.2.1.1 Channel Input Pins — AD1P7–AD1P0
The channel pins are used as the analog input pins of the ATD. Each pin is connected to an analog switch
which serves as the signal gate into the sample submodule.
14.2.1.2 ATD Reference Pins — VREFH, VREFL
These pins serve as the source for the high and low reference potentials for the converter. Separation from
the power supply pins accommodates the filtering necessary to achieve the accuracy of which the system
is capable.
14.2.1.3 ATD Supply Pins — VDDAD, VSSAD
These two pins are used to supply power and ground to the analog section of the ATD. Dedicated power
is required to isolate the sensitive analog circuitry from the normal levels of noise present on digital power
supplies.
NOTE
VDDAD1 and VDD must be at the same potential. Likewise, VSSAD1 and VSS
must be at the same potential.
14.3
Functional Description
The ATD uses a successive approximation register (SAR) architecture. The ATD contains all the necessary
elements to perform a single analog-to-digital conversion.
A write to the ATD1SC register initiates a new conversion. A write to the ATD1C register will interrupt
the current conversion but it will not initiate a new conversion. A write to the ATD1PE register will also
abort the current conversion but will not initiate a new conversion. If a conversion is already running when
a write to the ATD1SC register is made, it will be aborted and a new one will be started.
14.3.1
Mode Control
The ATD has a mode control unit to communicate with the sample and hold (S/H) machine and the SAR
machine when necessary to collect samples and perform conversions. The mode control unit signals the
S/H machine to begin collecting a sample and for the SAR machine to begin receiving a sample. At the
end of the sample period, the S/H machine signals the SAR machine to begin the analog-to-digital
conversion process. The conversion process is terminated when the SAR machine signals the end of
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
223
Analog-to-Digital Converter (ATD) Module
conversion to the mode control unit. For VREFL and VREFH, the SAR machine uses the reference potentials
to set the sampled signal level within itself without relying on the S/H machine to deliver them.
The mode control unit organizes the conversion, specifies the input sample channel, and moves the digital
output data from the SAR register to the result register. The result register consists of a dual-port register.
The SAR register writes data into the register through one port while the module data bus reads data out
of the register through the other port.
14.3.2
Sample and Hold
The S/H machine accepts analog signals and stores them as capacitor charge on a storage node located in
the SAR machine. Only one sample can be held at a time so the S/H machine and the SAR machine can
not run concurrently even though they are independent machines. Figure 14-3 shows the placement of the
various resistors and capacitors.
INPUT PIN
RAS
ATD SAR
ENGINE
RAIN1
VAIN
+
–
CAS
INPUT PIN
CHANNEL
SELECT 0
RAIN2
CHANNEL
SELECT 1
INPUT PIN
RAIN3
.
.
.
INPUT PIN
CHANNEL
SELECT 2
RAINn
CHANNEL
SELECT n
CAIN
Figure 14-3. Resistor and Capacitor Placement
When the S/H machine is not sampling, it disables its own internal clocks.The input analog signals are
unipolar. The signals must fall within the potential range of VSSAD to VDDAD. The S/H machine is not
required to perform special conversions (i.e., convert VREFL and VREFH).
Proper sampling is dependent on the following factors:
• Analog source impedance (the real portion, RAS – see Appendix A, “Electrical Characteristics”)
— This is the resistive (or real, in the case of high frequencies) portion of the network driving the
analog input voltage VAIN.
• Analog source capacitance (CAS) — This is the filtering capacitance on the analog input, which (if
large enough) may help the analog source network charge the ATD input in the case of high RAS.
• ATD input resistance (RAIN – maximum value 7 kΩ) — This is the internal resistance of the ATD
circuit in the path between the external ATD input and the ATD sample and hold circuit. This
resistance varies with temperature, voltage, and process variation but a worst case number is
necessary to compute worst case sample error.
MC9S08GB/GT Data Sheet, Rev. 2.3
224
Freescale Semiconductor
Functional Description
•
•
•
•
•
ATD input capacitance (CAIN – maximum value 50 pF) — This is the internal capacitance of the
ATD sample and hold circuit. This capacitance varies with temperature, voltage, and process
variation but a worst case number is necessary to compute worst case sample error.
ATD conversion clock frequency (fATDCLK – maximum value 2 MHz) — This is the frequency of
the clock input to the ATD and is dependent on the bus clock frequency and the ATD prescaler.
This frequency determines the width of the sample window, which is 14 ATDCLK cycles.
Input sample frequency (fSAMP – see Appendix A, “Electrical Characteristics”) — This is the
frequency that a given input is sampled.
Delta-input sample voltage (∆VSAMP) — This is the difference between the current input voltage
(intended for conversion) and the previously sampled voltage (which may be from a different
channel). In non-continuous convert mode, this is assumed to be the greater of (VREFH – VAIN) and
(VAIN – VREFL). In continuous convert mode, 5 LSB should be added to the known difference to
account for leakage and other losses.
Delta-analog input voltage (∆VAIN) — This is the difference between the current input voltage and
the input voltage during the last conversion on a given channel. This is based on the slew rate of
the input.
In cases where there is no external filtering capacitance, the sampling error is determined by the number
of time constants of charging and the change in input voltage relative to the resolution of the ATD:
# of time constants (τ) = (14 / fATDCLK) / ((RAS + RAIN) * CAIN)
Eqn. 14-1
sampling error in LSB (ES) = 2N * (∆VSAMP / (VREFH - VREFL)) * e−τ
The maximum sampling error (assuming maximum change on the input voltage) will be:
ES = (3.6/3.6) * e–(14/((7 k + 10 k) * 50 p * 2 M)) * 1024 = 0.271 LSB
Eqn. 14-2
In the case where an external filtering capacitance is applied, the sampling error can be reduced based on
the size of the source capacitor (CAS) relative to the analog input capacitance (CAIN). Ignoring the analog
source impedance (RAS), CAS will charge CAIN to a value of:
ES = 2N * (∆VSAMP / (VREFH – VREFL)) * (CAIN / (CAIN + CAS))
Eqn. 14-3
In the case of a 0.1 µF CAS, a worst case sampling error of 0.5 LSB is achieved regardless of RAS.
However, in the case of repeated conversions at a rate of fSAMP, RAS must re-charge CAS. This recharge is
continuous and controlled only by RAS (not RAIN), and reduces the overall sampling error to:
ES = 2N * {(∆VAIN / (VREFH – VREFL)) * e−(1 / (fSAMP * RAS * CAS )
+ (∆VSAMP / (VREFH - VREFL)) * Min[(CAIN / (CAIN + CAS)), e−(1 / (fATDCLK * (RAS + RAIN) * CAIN )]}
Eqn. 14-4
This is a worst case sampling error which does not account for RAS recharging the combination of CAS
and CAIN during the sample window. It does illustrate that high values of RAS (>10 kΩ) are possible if a
large CAS is used and sufficient time to recharge CAS is provided between samples. In order to achieve
accuracy specified under the worst case conditions of maximum ∆VSAMP and minimum CAS, RAS must
be less than the maximum value of 10 kΩ. The maximum value of 10 kΩ for RAS is to ensure low sampling
error in the worst case condition of maximum ∆VSAMP and minimum CAS.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
225
Analog-to-Digital Converter (ATD) Module
14.3.3
Analog Input Multiplexer
The analog input multiplexer selects one of the eight external analog input channels to generate an analog
sample. The analog input multiplexer includes negative stress protection circuitry which prevents
cross-talk between channels when the applied input potentials are within specification. Only analog input
signals within the potential range of VREFL to VREFH (ATD reference potentials) will result in valid ATD
conversions.
14.3.4
ATD Module Accuracy Definitions
Figure 14-4 illustrates an ideal ATD transfer function. The horizontal axis represents the ATD input
voltage in millivolts. The vertical axis the conversion result code. The ATD is specified with the following
figures of merit:
• Number of bits (N) — The number of bits in the digitized output
• Resolution (LSB) — The resolution of the ATD is the step size of the ideal transfer function. This
is also referred to as the ideal code width, or the difference between the transition voltages to a
given code and to the next code. This unit, known as 1LSB, is equal to
1LSB = (VREFH – VREFL) / 2N
•
•
•
Eqn. 14-5
Inherent quantization error (EQ) — This is the error caused by the division of the perfect ideal
straight-line transfer function into the quantized ideal transfer function with 2N steps. This error is
± 1/2 LSB.
Differential non-linearity (DNL) — This is the difference between the current code width and the
ideal code width (1LSB). The current code width is the difference in the transition voltages to the
current code and to the next code. A negative DNL means the transfer function spends less time at
the current code than ideal; a positive DNL, more. The DNL cannot be less than –1.0; a DNL of
greater than 1.0 reduces the effective number of bits by 1.
Integral non-linearity (INL) — This is the difference between the transition voltage to the current
code and the transition to the corresponding code on the adjusted transfer curve. INL is a measure
of how straight the line is (how far it deviates from a straight line). The adjusted ideal transition
voltage is:
Eqn. 14-6
Adjusted Ideal Trans. V = (Current Code - 1/2) * ((VREFH + EFS) - (VREFL + EZS))
2N
•
Zero scale error (EZS) — This is the difference between the transition voltage to the first valid code
and the ideal transition to that code. Normally, it is defined as the difference between the actual and
ideal transition to code $001, but in some cases the first transition may be to a higher code. The
ideal transition to any code is:
Eqn. 14-7
Ideal Transition V =
(Current Code - 1/2)
2N
*(VREFH – VREFL)
MC9S08GB/GT Data Sheet, Rev. 2.3
226
Freescale Semiconductor
Functional Description
•
Full scale error (EFS) — This is the difference between the transition voltage to the last valid code
and the ideal transition to that code. Normally, it is defined as the difference between the actual and
ideal transition to code $3FF, but in some cases the last transition may be to a lower code. The ideal
transition to any code is:
Eqn. 14-8
Ideal Transition V =
•
•
(Current Code - 1/2)
2N
*(VREFH – VREFL)
Total unadjusted error (ETU) — This is the difference between the transition voltage to a given code
and the ideal straight-line transfer function. An alternate definition (with the same result) is the
difference between the actual transfer function and the ideal straight-line transfer function. This
measure of error includes inherent quantization error and all forms of circuit error (INL, DNL,
zero-scale, and full-scale) except input leakage error, which is not due to the ATD.
Input leakage error (EIL) — This is the error between the transition voltage to the current code and
the ideal transition to that code that is the result of input leakage across the real portion of the
impedance of the network that drives the analog input. This error is a system-observable error
which is not inherent to the ATD, so it is not added to total error. This error is:
EIL (in V) = input leakage * RAS
Eqn. 14-9
There are two other forms of error which are not specified which can also affect ATD accuracy. These are:
• Sampling error (ES) — The error due to inadequate time to charge the ATD circuitry
• Noise error (EN) — The error due to noise on VAIN, VREFH, or VREFL due to either direct coupling
(noise source capacitively coupled directly on the signal) or power supply (VDDAD, VSSAD, VDD,
and VSS) noise interfering with the ATD’s ability to resolve the input accurately. The error due to
internal sources can be reduced (and specified operation achieved) by operating the ATD
conversion in wait mode and ceasing all IO activity. Reducing the error due to external sources is
dependent on system activity and board layout.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
227
Analog-to-Digital Converter (ATD) Module
CODE
D
C
TOTAL UNADJUSTED
ERROR BOUNDARY
B
A
IDEAL TRANSFER
FUNCTION
9
NEGATIVE DNL
(CODE WIDTH <1LSB)
8
IDEAL STRAIGHT-LINE
7
TRANSFER FUNCTION
QUANTIZATION
ERROR
6
INL
(ASSUMES EZS = EFS = 0)
5
1 LSB
4
TOTAL UNADJUSTED
3
ERROR AT THIS CODE
2
POSITIVE DNL
1
(CODE WIDTH >1LSB)
0
1
2
3
4
8
12
LSB
NOTES: Graph is for example only and may not represent actual performance
Figure 14-4. ATD Accuracy Definitions
MC9S08GB/GT Data Sheet, Rev. 2.3
228
Freescale Semiconductor
Resets
14.4
Resets
The ATD module is reset on system reset. If the system reset signal is activated, the ATD registers are
initialized back to their reset state and the ATD module is powered down. This occurs as a function of the
register file initialization; the reset definition of the ATDPU bit (power down bit) is zero or disabled.
The MCU places the module back into an initialized state. If the module is performing a conversion, the
current conversion is terminated, the conversion complete flag is cleared, and the SAR register bits are
cleared. Any pending interrupts are also cancelled. Note that the control, test, and status registers are
initialized on reset; the initialized register state is defined in the register description section of this
specification.
Enabling the module (using the ATDPU bit) does not cause the module to reset since the register file is not
initialized. Finally, writing to control register ATD1C does not cause the module to reset; the current
conversion will be terminated.
14.5
Interrupts
The ATD module originates interrupt requests and the MCU handles or services these requests. Details on
how the ATD interrupt requests are handled can be found in Chapter 5, “Resets, Interrupts, and System
Configuration”.
The ATD interrupt function is enabled by setting the ATDIE bit in the ATD1SC register. When the ATDIE
bit is set, an interrupt is generated at the end of an ATD conversion and the ATD result registers (ATD1RH
and ATD1RL) contain the result data generated by the conversion. If the interrupt function is disabled
(ATDIE = 0), then the CCF flag must be polled to determine when a conversion is complete.
The interrupt will remain pending as long as the CCF flag is set. The CCF bit is cleared whenever the ATD
status and control (ATD1SC) register is written. The CCF bit is also cleared whenever the ATD result
registers (ATD1RH or ATD1RL) are read.
Table 14-2. Interrupt Summary
14.6
Interrupt
Local
Enable
Description
CCF
ATDIE
Conversion complete
ATD Registers and Control Bits
The ATD has seven registers which control ATD functions.
Refer to the direct-page register summary in Chapter 4, “Memory” of this data sheet for the absolute
address assignments for all ATD 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
229
Analog-to-Digital Converter (ATD) Module
14.6.1
ATD Control (ATDC)
Bit 7
6
5
4
ATDPU
DJM
RES8
SGN
0
0
0
0
3
2
1
Bit 0
0
0
Read:
PRS
Write:
Reset:
0
0
Figure 14-5. ATD Control Register (ATD1C)
Writes to the ATD control register will abort the current conversion, but will not start a new conversion.
ATDPU — ATD Power Up
This bit provides program on/off control over the ATD, reducing power consumption when the ATD
is not being used. When cleared, the ATDPU bit aborts any conversion in progress.
1 = ATD functionality.
0 = Disable the ATD and enter a low-power state.
DJM — Data Justification Mode
This bit determines how the 10-bit conversion result data maps onto the ATD result register bits. When
RES8 is set, bit DJM has no effect and the 8-bit result is always located in ATD1RH.
For left-justified mode, result data bits 9–2 map onto bits 7–0 of ATD1RH, result data bits 1 and 0 map
onto ATD1RL bits 7 and 6, where bit 7 of ATD1RH is the most significant bit (MSB).
7
6
5
4
3
9
2
1
0
7
6
5
4
3
2
1
0
0
RESULT
ATD1RH
ATD1RL
Figure 14-6. Left-Justified Mode
For right-justified mode, result data bits 9 and 8 map onto bits 1 and 0 of ATD1RH, result data bits
7–0 map onto ATD1RL bits 7–0, where bit 1 of ATD1RH is the most significant bit (MSB).
7
6
5
4
3
2
1
0
7
6
9
ATD1RH
5
RESULT
4
3
2
1
0
0
ATD1RL
Figure 14-7. Right-Justified Mode
The effect of the DJM bit on the result is shown in Table 14-3.
1 = Result register data is right justified.
0 = Result register data is left justified.
MC9S08GB/GT Data Sheet, Rev. 2.3
230
Freescale Semiconductor
ATD Registers and Control Bits
RES8 — ATD Resolution Select
This bit determines the resolution of the ATD converter, 8-bits or 10-bits. The ATD converter has the
accuracy of a 10-bit converter. However, if 8-bit compatibility is required, selecting 8-bit resolution
will map result data bits 9-2 onto ATD1RH bits 7-0.
The effect of the RES8 bit on the result is shown in Table 14-3.
1 = 8-bit resolution selected.
0 = 10-bit resolution selected.
SGN — Signed Result Select
This bit determines whether the result will be signed or unsigned data. Signed data is represented as
2’s complement data and is achieved by complementing the MSB of the result. Signed data mode can
be used only when the result is left justified (DJM = 0) and is not available for right-justified mode
(DJM = 1). When a signed result is selected, the range for conversions becomes –512 ($200) to 511
($1FF) for 10-bit resolution and –128 ($80) to 127 ($7F) for 8-bit resolution.
The effect of the SGN bit on the result is shown in Table 14-3.
1 = Left justified result data is signed.
0 = Left justified result data is unsigned.
Table 14-3. Available Result Data Formats
RES8
DJM
SGN
Data Formats of Result
Analog Input
VREFH = VDDA, VREFL = VSSA
ATD1RH:ATD1RL
VDDA
VSSA
1
0
0
8-bit : left justified : unsigned
$FF:$00
$00:$00
1
0
1
8-bit : left justified : signed
$7F:$00
$80:$00
1
1
X1
8-bit : left
justified2
: unsigned
$FF:$00
$00:$00
0
0
0
10-bit : left justified : unsigned
$FF:$C0
$00:$00
0
0
1
10-bit : left justified : signed
$7F:$C0
$80:$00
10-bit : right justified : unsigned
$03:$FF
$00:$00
0
1
2
1
1
X
The SGN bit is only effective when DJM = 0. When DJM = 1, SGN is ignored.
8-bit results are always in ATD1RH.
PRS — Prescaler Rate Select
This field of bits determines the prescaled factor for the ATD conversion clock. Table 14-4 illustrates
the divide-by operation and the appropriate range of bus clock frequencies.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
231
Analog-to-Digital Converter (ATD) Module
Table 14-4. Clock Prescaler Values
PRS
Factor = (PRS +1) × 2
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
Min Bus Clock3
Max Bus Clock
Max Bus Clock
MHz
MHz
MHz
(2 MHz max ATD Clock)1 (1 MHz max ATD Clock)2 (500 kHz min ATD Clock)
4
8
12
16
20
20
20
20
20
20
20
20
20
20
20
20
2
4
6
8
10
12
14
16
18
20
20
20
20
20
20
20
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
Maximum ATD conversion clock frequency is 2 MHz. The max bus clock frequency is computed from the max ATD conversion
clock frequency times the indicated prescaler setting; i.e., for a PRS of 0, max bus clock = 2 (max ATD conversion clock
frequency) × 2 (Factor) = 4 MHz.
2 Use these settings if the maximum desired ATD conversion clock frequency is 1 MHz. The max bus clock frequency is
computed from the max ATD conversion clock frequency times the indicated prescaler setting; i.e., for a PRS of 0, max bus
clock = 1 (max ATD conversion clock frequency) × 2 (Factor) = 2 MHz.
3 Minimum ATD conversion clock frequency is 500 kHz. The min bus clock frequency is computed from the min ATD conversion
clock frequency times the indicated prescaler setting; i.e., for a PRS of 1, min bus clock = 0.5 (min ATD conversion clock
frequency) × 2 (Factor) = 1 MHz.
14.6.2
ATD Status and Control (ATD1SC)
Bit 7
Read:
6
5
ATDIE
ATDCO
0
0
4
3
2
1
Bit 0
0
1
CCF
ATDCH
Write:
Reset:
0
0
0
0
= Unimplemented or Reserved
Figure 14-8. ATD Status and Control Register (ATD1SC)
Writes to the ATD status and control register clears the CCF flag, cancels any pending interrupts, and
initiates a new conversion.
MC9S08GB/GT Data Sheet, Rev. 2.3
232
Freescale Semiconductor
ATD Registers and Control Bits
CCF — Conversion Complete Flag
The CCF is a read-only bit which is set each time a conversion is complete. The CCF bit is cleared
whenever the ATD1SC register is written. It is also cleared whenever the result registers, ATD1RH or
ATD1RL, are read.
1 = Current conversion is complete.
0 = Current conversion is not complete.
ATDIE — ATD Interrupt Enabled
When this bit is set, an interrupt is generated upon completion of an ATD conversion. At this time, the
result registers contain the result data generated by the conversion. The interrupt will remain pending
as long as the conversion complete flag CCF is set. If the ATDIE bit is cleared, then the CCF bit must
be polled to determine when the conversion is complete. Note that system reset clears pending
interrupts.
1 = ATD interrupt enabled.
0 = ATD interrupt disabled.
ATDCO — ATD Continuous Conversion
When this bit is set, the ATD will convert samples continuously and update the result registers at the
end of each conversion. When this bit is cleared, only one conversion is completed between writes to
the ATD1SC register.
1 = Continuous conversion mode.
0 = Single conversion mode.
ATDCH — Analog Input Channel Select
This field of bits selects the analog input channel whose signal is sampled and converted to digital
codes. Table 14-5 lists the coding used to select the various analog input channels.
Table 14-5. Analog Input Channel Select Coding
ATDCH
Analog Input Channel
00
AD0
01
AD1
02
AD2
03
AD3
04
AD4
05
AD5
06
AD6
07
AD7
08–1D
Reserved (default to VREFL)
1E
VREFH
1F
VREFL
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
233
Analog-to-Digital Converter (ATD) Module
14.6.3
ATD Result Data (ATD1RH, ATD1RL)
For left-justified mode, result data bits 9–2 map onto bits 7–0 of ATD1RH, result data bits 1 and 0 map
onto ATD1RL bits 7 and 6, where bit 7 of ATD1RH is the most significant bit (MSB).
7
6
5
4
3
9
2
1
0
7
6
5
4
3
2
1
0
0
RESULT
ATD1RH
ATD1RL
Figure 14-9. Left-Justified Mode
For right-justified mode, result data bits 9 and 8 map onto bits 1 and 0 of ATD1RH, result data bits 7–0
map onto ATD1RL bits 7–0, where bit 1 of ATD1RH is the most significant bit (MSB).
7
6
5
4
3
2
1
0
7
6
9
5
4
3
2
1
0
RESULT
ATD1RH
0
ATD1RL
Figure 14-10. Right-Justified Mode
The ATD 10-bit conversion results are stored in two 8-bit result registers, ATD1RH and ATD1RL. The
result data is formatted either left or right justified where the format is selected using the DJM control bit
in the ATD1C register. The 10-bit result data is mapped either between ATD1RH bits 7–0 and ATD1RL
bits 7–6 (left justified), or ATD1RH bits 1–0 and ATD1RL bits 7–0 (right justified).
For 8-bit conversions, the 8-bit result is always located in ATD1RH bits 7–0, and the ATD1RL bits read 0.
For 10-bit conversions, the six unused bits always read 0.
The ATD1RH and ATD1RL registers are read-only.
14.6.4
ATD Pin Enable (ATD1PE)
Bit 7
6
5
4
3
2
1
Bit 0
ATDPE7
ATDPE6
ATDPE5
ATDPE4
ATDPE3
ATDPE2
ATDPE1
ATDPE0
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 14-11. ATD Pin Enable Register (ATD1PE)
The ATD pin enable register allows the pins dedicated to the ATD module to be configured for ATD usage.
A write to this register will abort the current conversion but will not initiate a new conversion. If the
ATDPEx bit is 0 (disabled for ATD usage) but the corresponding analog input channel is selected via the
ATDCH bits, the ATD will not convert the analog input but will instead convert VREFL placing zeroes in
the ATD result registers.
ATDPE7:ATDPE0 — ATD Pin 7–0 Enables
1 = Pin enabled for ATD usage.
0 = Pin disabled for ATD usage.
MC9S08GB/GT Data Sheet, Rev. 2.3
234
Freescale Semiconductor
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 MC9S08GB/GT is the ICGLCLK. See Chapter 7, “Internal Clock
Generator (ICG) Module,” for more information about ICGCLK and how to select clock sources.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
235
Development Support
15.2
Features
Features of the background debug controller (BDC) 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 debug module (DBG) include:
• 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:
— A-only
— A OR B
— A then B
— A AND B data (full mode)
— A AND NOT B data (full mode)
— Event-only B (store data)
— A then event-only B (store data)
— Inside range (A ≤ address ≤ B)
— Outside range (address < A or address > B)
MC9S08GB/GT Data Sheet, Rev. 2.3
236
Freescale Semiconductor
Background Debug Controller (BDC)
15.3
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.
• 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
15.3.1
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
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
237
Development Support
first (MSB first). For a detailed description of the communications protocol, refer to Section 15.3.2,
“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 15.3.2, “Communication Details,” for more detail.
When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD
chooses normal operating mode. When a development system is connected, it can pull both BKGD and
RESET low, release RESET to select active background mode rather than normal operating mode, then
release BKGD. It is not necessary to reset the target MCU to communicate with it through the background
debug interface.
15.3.2
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
238
Freescale Semiconductor
Background Debug Controller (BDC)
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
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
239
Development Support
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)
MC9S08GB/GT Data Sheet, Rev. 2.3
240
Freescale Semiconductor
Background Debug Controller (BDC)
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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Development Support
15.3.3
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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Background Debug Controller (BDC)
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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Development Support
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.
15.3.4
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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On-Chip Debug System (DBG)
15.4
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 15.4.6, “Hardware Breakpoints.”
15.4.1
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)
15.4.2
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 15.4.5, “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.
15.4.3
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.
15.4.4
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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On-Chip Debug System (DBG)
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.
15.4.5
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 the ARM bit or DBGEN bit 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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Development Support
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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Registers and Control Bits
15.4.6
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 15.4.5, “Trigger Modes,” to be used to generate a hardware breakpoint request to the
CPU. The TAG bit 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.
15.5
Registers and Control Bits
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.
15.5.1
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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15.5.1.1 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.
Bit 7
Read:
6
5
4
3
BKPTEN
FTS
CLKSW
BDMACT
ENBDM
2
1
Bit 0
WS
WSF
DVF
Write:
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)
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.
1 = BDM can be made active to allow active background mode commands.
0 = BDM cannot be made active (non-intrusive commands still allowed).
BDMACT — Background Mode Active Status
This is a read-only status bit.
1 = BDM active and waiting for serial commands.
0 = BDM not active (user application program running).
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.
1 = BDC breakpoint enabled.
0 = BDC breakpoint disabled.
FTS — 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.
1 = Breakpoint match forces active background mode at next instruction boundary (address need
not be an opcode).
0 = Tag opcode at breakpoint address and enter active background mode if CPU attempts to execute
that instruction.
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Registers and Control Bits
CLKSW — Select Source for BDC Communications Clock
CLKSW defaults to 0, which selects the alternate BDC clock source.
1 = MCU bus clock.
0 = Alternate BDC clock source.
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.
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.
0 = Target CPU is running user application code or in active background mode (was not in wait or
stop mode when background became active).
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.)
1 = Memory access command failed because the CPU entered wait or stop mode.
0 = Memory access did not conflict with a wait or stop instruction.
DVF — Data Valid Failure Status
This status bit is not used in the MC9S08GB/GT because it does not have any slow access memory.
1 = Memory access command failed because CPU was not finished with a slow memory access.
0 = Memory access did not conflict with a slow memory access.
15.5.1.2 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 15.3.4, “BDC Hardware Breakpoint.”
15.5.2
System Background Debug Force Reset Register (SBDFR)
This register contains a single write-only control bit. A serial active 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 $00.
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Development Support
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
BDFR1
Write:
Reset:
0
0
0
1
0
0
0
0
= Unimplemented or Reserved
1
BDFR is writable only through serial active background mode debug commands, not from user programs.
Figure 15-6. System Background Debug Force Reset Register (SBDFR)
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.
15.5.3
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.
15.5.3.1 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 $00 at reset and can be read at any time or written at any time unless ARM = 1.
15.5.3.2 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 $00 at reset and can be read at any time or written at any time unless ARM = 1.
15.5.3.3 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 $00 at reset and can be read at any time or written at any time unless ARM = 1.
15.5.3.4 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 $00 at reset and can be read at any time or written at any time unless ARM = 1.
MC9S08GB/GT Data Sheet, Rev. 2.3
252
Freescale Semiconductor
Registers and Control Bits
15.5.3.5 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 $00.
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.
15.5.3.6 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
253
Development Support
15.5.3.7 Debug Control Register (DBGC)
This register can be read or written at any time.
Bit 7
6
5
4
3
2
1
Bit 0
DBGEN
ARM
TAG
BRKEN
RWA
RWAEN
RWB
RWBEN
0
0
0
0
0
0
0
0
Read:
Write:
Reset:
Figure 15-7. Debug Control Register (DBGC)
DBGEN — Debug Module Enable
Used to enable the debug module. DBGEN cannot be set to 1 if the MCU is secure.
1 = DBG enabled.
0 = DBG disabled.
ARM — Arm Control
Controls whether the debugger is comparing and storing information in the FIFO. A write is used to
set this bit (and the ARMF bit) and completion of a debug run automatically clears it. Any debug run
can be manually stopped by writing 0 to ARM or to DBGEN.
1 = Debugger armed.
0 = Debugger not armed.
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.
1 = CPU breaks requested as tag type requests.
0 = CPU breaks requested as force type requests.
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.
1 = Triggers cause a break request to the CPU.
0 = CPU break requests not enabled.
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.
1 = Comparator A can only match on a read cycle.
0 = Comparator A can only match on a write cycle.
MC9S08GB/GT Data Sheet, Rev. 2.3
254
Freescale Semiconductor
Registers and Control Bits
RWAEN — Enable R/W for Comparator A
Controls whether the level of R/W is considered for a comparator A match.
1 = R/W is used in comparison A.
0 = R/W is not used in comparison A.
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.
1 = Comparator B can match only on a read cycle.
0 = Comparator B can match only on a write cycle.
RWBEN — Enable R/W for Comparator B
Controls whether the level of R/W is considered for a comparator B match.
1 = R/W is used in comparison B.
0 = R/W is not used in comparison B.
15.5.3.8 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.
Bit 7
6
TRGSEL
BEGIN
0
0
Read:
5
4
0
0
3
2
1
Bit 0
TRG3
TRG2
TRG1
TRG0
0
0
0
0
Write:
Reset:
0
0
= Unimplemented or Reserved
Figure 15-8. Debug Trigger Register (DBGT)
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.
1 = Trigger if opcode at compare address is executed (tag).
0 = Trigger on access to compare address (force).
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.
1 = Trigger initiates data storage (begin trace).
0 = Data stored in FIFO until trigger (end trace).
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
255
Development Support
TRG3:TRG2:TRG1:TRG0 — Select Trigger Mode
Selects one of nine triggering modes
Table 15-2. Trigger Mode Selection
TRG[3:0]
Triggering Mode
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
15.5.3.9 Debug Status Register (DBGS)
This is a read-only status register.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
AF
BF
ARMF
0
CNT3
CNT2
CNT1
CNT0
0
0
0
0
0
0
0
0
Write:
Reset:
= Unimplemented or Reserved
Figure 15-9. Debug Status Register (DBGS)
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.
1 = Comparator A match.
0 = Comparator A has not matched.
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.
1 = Comparator B match.
0 = Comparator B has not matched.
MC9S08GB/GT Data Sheet, Rev. 2.3
256
Freescale Semiconductor
Registers and Control Bits
ARMF — Arm Flag
While DBGEN = 1, this status bit is a read-only image of the ARM bit 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 the ARM or DBGEN
bits in DBGC.
1 = Debugger armed.
0 = Debugger not armed.
CNT3:CNT2:CNT1:CNT0 — 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.
Table 15-3. CNT Status Bits
CNT[3:0]
Valid Words in FIFO
0000
No valid data
0001
1
0010
2
0011
3
0100
4
0101
5
0110
6
0111
7
1000
8
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
257
Development Support
MC9S08GB/GT Data Sheet, Rev. 2.3
258
Freescale Semiconductor
Appendix A Electrical Characteristics
A.1
Introduction
This section contains electrical and timing specifications.
A.2
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-1 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) or the programmable
pull-up resistor associated with the pin is enabled.
Table A-1. Absolute Maximum Ratings
Rating
Symbol
Value
Unit
Supply voltage
VDD
–0.3 to +3.8
V
Maximum current into VDD
IDD
120
mA
Digital 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
Tstg
–55 to 150
°C
Storage temperature range
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 V
SS 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.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
259
Appendix A Electrical Characteristics
A.3
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 voltage regulator circuits 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-2. Thermal Characteristics
Rating
Operating temperature range (packaged)
Thermal resistance
64-pin LQFP (GB60)
48-pin QFN (GT60)
42-pin SDIP (GT60)
44-pin QFP (GT60)
Symbol
Value
Unit
Temp.
Code
TA
–40 to 85
°C
C
θJA1, 2
65
82
57
118
°C/W
—
1
Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance,
mounting site (board) temperature, ambient temperature, airflow, power dissipation of other components
on the board, and board thermal resistance.
2 Per SEMI G38-87 and JEDEC JESD51-2 with the single layer board horizontal. Single layer board is
designed per JEDEC JESD51-3.
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:
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
260
Freescale Semiconductor
Electrostatic Discharge (ESD) Protection Characteristics
A.4
Electrostatic Discharge (ESD) Protection Characteristics
Although damage from static discharge 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 CDF-AEC-Q00 Stress
Test Qualification for Automotive Grade Integrated Circuits. (http://www.aecouncil.com/) This device was
qualified to AEC-Q100 Rev E. A device is considered to have failed if, after exposure to ESD pulses, the
device no longer meets the device specification requirements. 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-3. ESD Protection Characteristics
Parameter
A.5
Symbol
Value
Unit
ESD Target for Machine Model (MM)
MM circuit description
VTHMM
200
V
ESD Target for Human Body Model (HBM)
HBM circuit description
VTHHBM
2000
V
DC Characteristics
This section includes information about power supply requirements, I/O pin characteristics, and power
supply current in various operating modes.
Table A-4. DC Characteristics (Sheet 1 of 2)
(Temperature Range = –40 to 85°C Ambient)
Parameter
Symbol
Min
VDD
Minimum RAM retention supply voltage applied to
VDD
Typical1
Max
Unit
1.8
2.08
3.6
3.6
V
VRAM
1.02
—
V
Low-voltage detection threshold — high range
(VDD falling)
(VDD rising)
VLVDH
2.08
2.16
2.1
2.19
2.2
2.27
V
Low-voltage detection threshold — low range
(VDD falling)
(VDD rising)
VLVDL
1.80
1.88
1.82
1.90
1.91
1.99
V
Low-voltage warning threshold — high range
(VDD falling)
(VDD rising)
VLVWH
2.35
2.35
2.40
2.40
2.5
V
Low-voltage warning threshold — low range
(VDD falling)
(VDD rising)
VLVWL
2.08
2.16
2.1
2.19
2.2
2.27
V
Supply voltage (run, wait and stop modes.)
0 < fBus < 8 MHz
0 < fBus < 20 MHz
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
261
Appendix A Electrical Characteristics
Table A-4. DC Characteristics (Sheet 2 of 2)
(Temperature Range = –40 to 85°C Ambient)
Parameter
Power on reset (POR) re-arm voltage(2)
Mode = stop
Mode = run and Wait
Symbol
Min
Typical1
Max
Unit
VRearm
0.20
0.50
0.30
0.80
0.40
1.2
V
Input high voltage (VDD > 2.3 V) (all digital inputs)
VIH
0.70 ×
VDD
—
V
Input high voltage (1.8 V ≤ VDD ≤ 2.3 V)
(all digital inputs)
VIH
0.85 ×
VDD
—
V
Input low voltage (VDD > 2.3 V) (all digital inputs)
VIL
—
0.35 ×
VDD
V
Input low voltage (1.8 V ≤ VDD ≤ 2.3 V)
(all digital inputs)
VIL
—
0.30 ×
VDD
V
Input hysteresis (all digital inputs)
Vhys
0.06 ×
VDD
—
V
Input leakage current (per pin)
VIn = VDD or VSS, all input only pins
|IIn|
—
0.025
1.0
µA
High impedance (off-state) leakage current (per pin)
VIn = VDD or VSS, all input/output
|IOZ|
—
0.025
1.0
µA
Internal pullup and pulldown resistors3
(all port pins and IRQ)
RPU
17.5
52.5
kW
Internal pulldown resistors (Port A4–A7 and IRQ)
RPD
17.5
52.5
kW
VDD – 0.5
—
Output high voltage (VDD ≥ 1.8 V)
IOH = –2 mA (ports A, B, D, E, and G)
Output high voltage (ports C and F)
IOH = –10 mA (VDD ≥ 2.7 V)
IOH = –6 mA (VDD ≥ 2.3 V)
IOH = –3 mA (VDD ≥ 1.8 V)
VOH
Maximum total IOH for all port pins
|IOHT|
VDD – 0.5
Output low voltage (VDD ≥ 1.8 V)
IOL = 2.0 mA (ports A, B, D, E, and G)
Output low voltage (ports C and F)
IOL = 10.0 mA (VDD ≥ 2.7 V)
IOL = 6 mA (VDD ≥ 2.3 V)
IOL = 3 mA (VDD ≥ 1.8 V)
VOL
Maximum total IOL for all port pins
IOLT
dc injection current4, 5, 6, 7, 8
VIN < VSS , VIN > VDD
Single pin limit
Total MCU limit, includes sum of all stressed pins
|IIC|
Input capacitance (all non-supply pins)(2)
CIn
—
—
—
V
—
60
mA
—
0.5
—
—
—
0.5
0.5
0.5
V
—
60
mA
—
—
0.2
5
mA
mA
—
7
pF
MC9S08GB/GT Data Sheet, Rev. 2.3
262
Freescale Semiconductor
DC Characteristics
2
3
4
5
6
7
8
Typicals are measured at 25°C.
This parameter is characterized and not tested on each device.
Measurement condition for pull resistors: VIn = VSS for pullup and VIn = VDD for pulldown.
Power supply must maintain regulation within operating VDD 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
clock rate is very low which would reduce overall power consumption.
All functional non-supply pins are internally clamped to VSS and VDD.
Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate
resistance values for positive and negative clamp voltages, then use the larger of the two values.
This parameter is characterized and not tested on each device.
IRQ does not have a clamp diode to VDD. Do not drive IRQ above VDD.
PULLUP RESISTOR TYPICALS
PULL-UP RESISTOR (kΩ)
40
85°C
25°C
–40°C
35
PULLDOWN RESISTANCE (kΩ)
1
30
25
20
1.8
2
2.2
2.4
2.6 2.8
VDD (V)
3
3.2
3.4
PULLDOWN RESISTOR TYPICALS
40
85°C
25°C
–40°C
35
30
25
20
3.6
1.8
2.3
2.8
VDD (V)
3.3
3.6
Figure A-1. Pullup and Pulldown Typical Resistor Values (VDD = 3.0 V)
TYPICAL VOL VS VDD
TYPICAL VOL VS IOL AT VDD = 3.0 V
1
0.4
85°C
25°C
–40°C
0.8
85°C
25°C
–40°C
0.3
VOL (V)
VOL (V)
0.6
0.4
0.2
IOL = 10 mA
IOL = 6 mA
0.1
0.2
IOL = 3 mA
0
0
0
10
20
30
1
2
3
4
VDD (V)
IOL (mA)
Figure A-2. Typical Low-Side Driver (Sink) Characteristics (Ports C and F)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
263
Appendix A Electrical Characteristics
TYPICAL VOL VS IOL AT VDD = 3.0 V
1.2
1
0.15
VOL (V)
0.8
VOL (V)
TYPICAL VOL VS VDD
0.2
85°C
25°C
–40°C
0.6
0.4
0.1
85°C, IOL = 2 mA
25°C, IOL = 2 mA
–40°C, IOL = 2 mA
0.05
0.2
0
0
0
5
10
IOL (mA)
15
1
20
2
3
4
VDD (V)
Figure A-3. Typical Low-Side Driver (Sink) Characteristics (Ports A, B, D, E, and G)
TYPICAL VDD – VOH VS VDD AT SPEC IOH
TYPICAL VDD – VOH VS IOH AT VDD = 3.0 V
0.8
85°C
25°C
–40°C
0.6
0.4
0.2
0
0
85°C
25°C
–40°C
0.3
VDD – VOH (V)
VDD – VOH (V)
0.4
–5
–10
–15
–20
–25
0.2
IOH = –10 mA
IOH = –6 mA
0.1
–30
IOH = –3 mA
0
IOH (mA)
1
2
3
4
VDD (V)
Figure A-4. Typical High-Side Driver (Source) Characteristics (Ports C and F)
TYPICAL VDD – VOH VS IOH AT VDD = 3.0 V
1.2
85°C, IOH = 2 mA
25°C, IOH = 2 mA
–40°C, IOH = 2 mA
0.2
VDD – VOH (V)
1
VDD – VOH (V)
TYPICAL VDD – VOH VS VDD AT SPEC IOH
0.25
85°C
25°C
–40°C
0.8
0.6
0.4
0.15
0.1
0.05
0.2
0
0
0
–5
–10
IOH (mA)
–15
–20
1
2
VDD (V)
3
4
Figure A-5. Typical High-Side (Source) Characteristics (Ports A, B, D, E, and G)
MC9S08GB/GT Data Sheet, Rev. 2.3
264
Freescale Semiconductor
Supply Current Characteristics
A.6
Supply Current Characteristics
Table A-5. Supply Current Characteristics
Parameter
Symbol
Typical1
Max2
Temp. (°C)
1.1 mA
2.1 mA4
2.1 mA(4)
2.1 mA(4)
55
70
85
0.8 mA
1.8 mA(4)
1.8 mA(4)
1.8 mA(4)
55
70
85
6.5 mA
7.5 mA(4)
7.5 mA(4)
7.5 mA5
55
70
85
4.8 mA
5.8 mA(4)
5.8 mA(4)
5.8 mA(4)
55
70
85
25 nA
0.6 µA(4)
1.8 µA(4)
4.0 µA(5)
55
70
85
20 nA
500 nA(4)
1.5 µA(4)
3.3 µA(4)
55
70
85
550 nA
3.0 µA(4)
5.5 µA(4)
11 µA(5)
55
70
85
2
400 nA
2.4 µA(4)
5.0 µA(4)
9.5 µA(4)
55
70
85
3
675 nA
4.3 µA(4)
7.2 µA(4)
17.0 µA(5)
55
70
85
2
500 nA
3.5 µA(4)
6.2 µA(4)
15.0 µA(4)
55
70
85
3
300 nA
55
70
85
2
300 nA
55
70
85
VDD (V)
3
3
Run supply current measured at
(CPU clock = 2 MHz, fBus = 1 MHz)
RIDD
2
3
Run supply current (3) measured at
(CPU clock = 16 MHz, fBus = 8 MHz)
RIDD
2
3
Stop1 mode supply current
S1IDD
2
3
Stop2 mode supply current
Stop3 mode supply current
S2IDD
S3IDD
RTI adder to stop2 or stop36
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
265
Appendix A Electrical Characteristics
Table A-5. Supply Current Characteristics (continued)
Parameter
Symbol
VDD (V)
Typical1
Max2
3
70 µA
55
70
85
2
60 µA
55
70
85
LVI adder to stop3
(LVDSE = LVDE = 1)
1
2
3
4
5
6
Temp. (°C)
Typicals are measured at 25°C. See Figure A-6 through Figure A-9 for typical curves across voltage/temperature.
Values given here are preliminary estimates prior to completing characterization.
All modules except ATD active, ICG configured for FBE, and does not include any dc loads on port pins
Values are characterized but not tested on every part.
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 and 422 µA at 2V with fBus = 1 MHz.
18
16
14
12
20 MHz, ATDoff, FEE, 25°C
IDD (mA)
10
20 MHz, ATDoff, FBE, 25°C
8 MHz, ATDoff, FEE, 25°C
8
8 MHz, ATDoff, FBE, 25°C
1 MHz, ATDoff, FEE, 25°C
6
1 MHz, ATDoff, FBE, 25°C
4
2
0
1.6
1.8
2.0
2.2
2.4
2.6
2.8
VDD (Vdc)
3.0
3.2
3.4
3.8
Figure A-6. Typical Run IDD for FBE and FEE Modes, IDD vs VDD
MC9S08GB/GT Data Sheet, Rev. 2.3
266
Freescale Semiconductor
Supply Current Characteristics
1200
STOP1 IDD (nA)
1000
800
25°C
70°C
600
85°C
400
200
0
1.5
2
2.5
3
3.5
4
VDD (V)
NOTES:
1. Clock sources and LVD are all disabled (OSCSTEN = LVDSE = 0).
2. All I/O are set as outputs and driven to VSS with no load.
Figure A-7. Typical Stop1 IDD
4
3.5
STOP2 IDD (µA)
3
2.5
25°C
2
70°C
85°C
1.5
1
0.5
0
1.5
2
2.5
3
3.5
4
VDD (V)
NOTES:
1. Clock sources and LVD are all disabled (OSCSTEN = LVDSE = 0).
2. All I/O are set as outputs and driven to VSS with no load.
Figure A-8. Typical Stop 2 IDD
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
267
Appendix A Electrical Characteristics
8
7
STOP3 IDD (µA)
6
5
25°C
4
70°C
85°C
3
2
1
0
1.5
2
2.5
3
3.5
4
VDD (V)
NOTES:
1. Clock sources and LVD are all disabled (OSCSTEN = LVDSE = 0).
2. All I/O are set as outputs and driven to VSS with no load.
Figure A-9. Typical Stop3 IDD
MC9S08GB/GT Data Sheet, Rev. 2.3
268
Freescale Semiconductor
ATD Characteristics
A.7
ATD Characteristics
Table A-6. ATD Electrical Characteristics (Operating)
Num
1
2
Characteristic
Condition
Symbol
Min
Typical
Max
Unit
VDDAD
1.80
—
3.6
V
Enabled
IDDADrun
—
0.7
1.2
mA
Disabled
(ATDPU = 0
or STOP)
IDDADstop
—
0.02
0.6
µA
ATD supply1
ATD supply current
3
Differential supply voltage
VDD–VDDAD
|VDDLT|
—
—
100
mV
4
Differential ground voltage
VSS–VSSAD
|VSDLT|
—
—
100
mV
|VREFL|
—
—
VSSAD
V
2.08
—
VDDAD
Reference potential, low
2.08V < VDDAD
< 3.6V
5
VREFH
Reference potential, high
1.80V < VDDAD
< 2.08V
6
7
1
2
Reference supply current
(VREFH to VREFL)
Analog input voltage2
V
VDDAD
—
VDDAD
Enabled
IREF
—
200
300
Disabled
(ATDPU = 0
or STOP)
IREF
—
<0.01
0.02
VINDC
VSSAD – 0.3
—
VDDAD + 0.3
µA
V
VDDAD must be at same potential as VDD.
Maximum electrical operating range, not valid conversion range.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
269
Appendix A Electrical Characteristics
Table A-7. ATD Timing/Performance Characteristics1
Num
1
Characteristic
ATD conversion clock
frequency
2
Conversion cycles (continuous
convert)2
3
Conversion time
Symbol
fATDCLK
Condition
Min
Typ
Max
2.08V < VDDAD < 3.6V
0.5
—
2.0
1.80V < VDDAD < 2.08V
0.5
—
1.0
28
28
<30
2.08V < VDDAD < 3.6V
14.0
—
60.0
1.80V < VDDAD < 2.08V
28.0
—
60.0
—
10
kΩ
VREFH
V
CC
Tconv
Unit
MHz
4
Source impedance at input3
RAS
—
5
Analog Input Voltage4
VAIN
VREFL
6
Ideal resolution (1 LSB)5
RES
7
Differential non-linearity6
8
9
ATDCLK
cycles
µS
2.08V < VDDAD < 3.6V
2.031
—
3.516
1.80V < VDDAD < 2.08V
1.758
—
2.031
DNL
1.80V < VDDAD < 3.6V
—
+0.5
+1.0
LSB
Integral non-linearity7
INL
1.80 V < VDDAD < 3.6V
—
+0.5
+1.0
LSB
Zero-scale error8
EZS
1.80V < VDDAD < 3.6V
—
+0.4
+1.0
LSB
EFS
1.80V < VDDAD < 3.6V
—
+0.4
+1.0
LSB
error9
mV
10
Full-scale
11
Input leakage error 10
EIL
1.80V < VDDAD < 3.6V
—
+0.05
+5
LSB
12
Total unadjusted
error11
ETU
1.80V < VDDAD < 3.6V
—
+1.1
+2.5
LSB
1
All ACCURACY numbers are based on processor and system being in WAIT state (very little activity and no IO switching) and
that adequate low-pass filtering is present on analog input pins (filter with 0.01 µF to 0.1 µF capacitor between analog input and
VREFL). Failure to observe these guidelines may result in system or microcontroller noise causing accuracy errors which will
vary based on board layout and the type and magnitude of the activity.
2 This is the conversion time for subsequent conversions in continuous convert mode. Actual conversion time for single
conversions or the first conversion in continuous mode is extended by one ATD clock cycle and 2 bus cycles due to starting the
conversion and setting the CCF flag. The total conversion time in Bus Cycles for a conversion is:
SC Bus Cycles = ((PRS+1)*2) * (28+1) + 2
CC Bus Cycles = ((PRS+1)*2) * (28)
3 R
AS is the real portion of the impedance of the network driving the analog input pin. Values greater than this amount may not
fully charge the input circuitry of the ATD resulting in accuracy error.
4 Analog input must be between V
REFL and VREFH for valid conversion. Values greater than VREFH will convert to $3FF less the
full scale error (EFS).
5 The resolution is the ideal step size or 1LSB = (V
REFH–VREFL)/1024
6 Differential non-linearity is the difference between the current code width and the ideal code width (1LSB). The current code
width is the difference in the transition voltages to and from the current code.
7 Integral non-linearity is the difference between the transition voltage to the current code and the adjusted ideal transition voltage
for the current code. The adjusted ideal transition voltage is (Current Code–1/2)*(1/((VREFH+EFS)–(VREFL+EZS))).
8
Zero-scale error is the difference between the transition to the first valid code and the ideal transition to that code. The Ideal
transition voltage to a given code is (Code–1/2)*(1/(VREFH–VREFL)).
9 Full-scale error is the difference between the transition to the last valid code and the ideal transition to that code. The ideal
transition voltage to a given code is (Code–1/2)*(1/(VREFH–VREFL)).
10 Input leakage error is error due to input leakage across the real portion of the impedance of the network driving the analog pin.
Reducing the impedance of the network reduces this error.
11
Total unadjusted error is the difference between the transition voltage to the current code and the ideal straight-line transfer
function. This measure of error includes inherent quantization error (1/2LSB) and circuit error (differential, integral, zero-scale,
and full-scale) error. The specified value of ET assumes zero EIL (no leakage or zero real source impedance).
MC9S08GB/GT Data Sheet, Rev. 2.3
270
Freescale Semiconductor
Internal Clock Generation Module Characteristics
A.8
Internal Clock Generation Module Characteristics
ICG
EXTAL
XTAL
RS
RF
Crystal or Resonator (See Note)
C1
C2
NOTE:
Use fundamental mode crystal or ceramic resonator only.
Table A-8. ICG DC Electrical Specifications (Temperature Range = –40 to 85°C Ambient)
Characteristic
Symbol
Load capacitors
Min
Typ1
C1
C2
Max
Unit
2
Feedback resistor
Low range (32k to 100 kHz)
High range (1M – 16 MHz)
RF
10
1
MΩ
MΩ
Series Resistor
RS
0
Ω
1
2
Data in Typical column was characterized at 3.0 V, 25°C or is typical recommended value.
See crystal or resonator manufacturer’s recommendation.
A.8.1
ICG Frequency Specifications
Table A-9. ICG Frequency Specifications
(VDDA = VDDA (min) to VDDA (max), Temperature Range = –40 to 85°C Ambient)
Characteristic
Symbol
Min
Typical
Max
Unit
Oscillator crystal or resonator (REFS = 1)
(Fundamental mode crystal or ceramic resonator)
Low range
High range, FLL bypassed external (CLKS = 10)
High range, FLL engaged external (CLKS = 11)
flo
fhi_byp
fhi_eng
32
2
2
—
—
—
100
16
10
kHz
MHz
MHz
Input clock frequency (CLKS = 11, REFS = 0)
Low range
High range
flo
fhi_eng
32
2
—
—
100
10
kHz
MHz
Input clock frequency (CLKS = 10, REFS = 0)
fExtal
0
—
40
MHz
fICGIRCLK
182.25
243
303.75
kHz
tdc
40
—
60
%
Internal reference frequency (untrimmed)
Duty cycle of input clock
4
(REFS = 0)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
271
Appendix A Electrical Characteristics
Table A-9. ICG Frequency Specifications (continued)
(VDDA = VDDA (min) to VDDA (max), Temperature Range = –40 to 85°C Ambient)
Characteristic
Symbol
Min
fICGOUT
fExtal (min)
flo (min)
Minimum DCO clock (ICGDCLK) frequency
fICGDCLKmin
8
Maximum DCO clock (ICGDCLK) frequency
fICGDCLKmax
Output clock ICGOUT frequency
CLKS = 10, REFS = 0
All other cases
Self-clock mode (ICGOUT) frequency 1
Self-clock mode reset (ICGOUT) frequency
Loss of reference frequency 2
Low range
High range
Loss of DCO frequency 3
fICGDCLKmin
fSelf_reset
5.5
fLOR
Crystal start-up time 4, 5
Low range
High range
Max
Unit
fExtal (max)
fICGDCLKmax
(max)
MHz
—
—
fSelf
fLOD
Typical
MHz
40
MHz
fICGDCLKmax
MHz
10.5
MHz
5
50
25
500
kHz
0.5
1.5
MHz
—
—
ms
8
t
CSTL
t
CSTH
—
—
FLL lock time 4, 6
Low range
High range
tLockl
tLockh
—
—
2
2
ms
FLL frequency unlock range
nUnlock
–4*N
4*N
counts
nLock
–2*N
2*N
counts
—
0.2
% fICG
FLL frequency lock range
430
4
4, 7 measured
at fICGOUT Max
ICGOUT period jitter,
Long term jitter (averaged over 2 ms interval)
Internal oscillator deviation from trimmed frequency 8
VDD = 1.8 – 3.6 V, (constant temperature)
VDD = 3.0 V ±10%, –40° C to 85° C
1
2
3
4
5
6
7
8
CJitter
ACCint
—
—
± 0.5
±0.5
±2
±2
%
Self-clocked mode frequency is the frequency that the DCO generates when the FLL is open-loop.
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.
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.
This parameter is characterized before qualification rather than 100% tested.
Proper PC board layout procedures must be followed to achieve specifications.
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.
Jitter is the average deviation from the programmed frequency measured over the specified interval at maximum fICGOUT.
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.
See Figure A-10
MC9S08GB/GT Data Sheet, Rev. 2.3
272
Freescale Semiconductor
AC Characteristics
0.1
80
–60
–40
–20
0
20
20
100
120
60
PERCENT (%)
–0.1
–0.2
–0.3
–0.4
2V
–0.5
3V
Note: Device trimmed at 25°C at 2 V
–0.6
TEMPERATURE (°C)
Figure A-10. Internal Oscillator Deviation from Trimmed Frequency
A.9
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 7, “Internal Clock Generator (ICG) Module.”
A.9.1
Control Timing
Table A-10. Control Timing
Parameter
Symbol
Min
Typical
Max
Unit
Bus frequency (tcyc = 1/fBus)
fBus
dc
—
20
MHz
Real-time interrupt internal oscillator period
tRTI
700
1300
µs
External reset pulse width1
textrst
1.5 x
fSelf_reset
—
ns
Reset low drive2
trstdrv
34 x
fSelf_reset
—
ns
Active background debug mode latch setup time
tMSSU
25
—
ns
Active background debug mode latch hold time
tMSH
25
—
ns
IRQ pulse width3
tILIH
1.5 x tcyc
—
ns
tRise, tFall
—
—
Port rise and fall time (load = 50 pF)4
Slew rate control disabled
Slew rate control enabled
3
30
ns
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
273
Appendix A Electrical Characteristics
1
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.
2
When any reset is initiated, internal circuitry drives the reset pin low for about 34 cycles of fSelf_reset and then samples the level
on the reset pin about 38 cycles later to distinguish external reset requests from internal requests.
3
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.
4
Timing is shown with respect to 20% VDD and 80% VDD levels. Temperature range –40°C to 85°C.
textrst
RESET PIN
Figure A-11. Reset Timing
BKGD/MS
RESET
tMSH
tMSSU
Figure A-12. Active Background Debug Mode Latch Timing
tILIH
IRQ
Figure A-13. IRQ Timing
A.9.2
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.
MC9S08GB/GT Data Sheet, Rev. 2.3
274
Freescale Semiconductor
AC Characteristics
Table A-11. 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
tText
tclkh
TPMxCHn
tclkl
Figure A-14. Timer External Clock
tICPW
TPMxCHn
TPMxCHn
tICPW
Figure A-15. Timer Input Capture Pulse
A.9.3
SPI Timing
Table A-12 and Figure A-16 through Figure A-19 describe the timing requirements for the SPI system.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
275
Appendix A Electrical Characteristics
Table A-12. SPI Timing
No.
Function
Operating frequency
Master
Slave
Symbol
Min
Max
Unit
fop
fBus/2048
dc
fBus/2
fBus/4
Hz
1
SCK period
Master
Slave
tSCK
2
4
2048
—
tcyc
tcyc
2
Enable lead time
Master
Slave
tLead
1/2
1
—
—
tSCK
tcyc
3
Enable lag time
Master
Slave
tLag
1/2
1
—
—
tSCK
tcyc
4
Clock (SCK) high or low time
Master
Slave
tWSCK
tcyc – 30
tcyc – 30
1024 tcyc
—
ns
ns
5
Data setup time (inputs)
Master
Slave
tSU
15
15
—
—
ns
ns
6
Data hold time (inputs)
Master
Slave
tHI
0
25
—
—
ns
ns
7
Slave access time
ta
—
1
tcyc
8
Slave MISO disable time
tdis
—
1
tcyc
9
Data valid (after SCK edge)
Master
Slave
tv
—
—
25
25
ns
ns
10
Data hold time (outputs)
Master
Slave
tHO
0
0
—
—
ns
ns
11
Rise time
Input
Output
tRI
tRO
—
—
tcyc – 25
25
ns
ns
12
Fall time
Input
Output
tFI
tFO
—
—
tcyc – 25
25
ns
ns
MC9S08GB/GT Data Sheet, Rev. 2.3
276
Freescale Semiconductor
AC Characteristics
SS1
(OUTPUT)
1
2
SCK
(CPOL = 0)
(OUTPUT)
11
3
4
4
12
SCK
(CPOL = 1)
(OUTPUT)
5
6
MISO
(INPUT)
MSB IN2
BIT 6 . . . 1
9
LSB IN
9
MOSI
(OUTPUT)
MSB OUT2
10
BIT 6 . . . 1
LSB OUT
NOTES:
1. SS output mode (DDS7 = 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 = 0)
SS(1)
(OUTPUT)
1
2
12
11
11
12
3
SCK
(CPOL = 0)
(OUTPUT)
4
4
SCK
(CPOL = 1)
(OUTPUT)
5
MISO
(INPUT)
6
MSB IN(2)
9
MOSI
(OUTPUT) PORT DATA
BIT 6 . . . 1
LSB IN
10
MASTER MSB OUT(2)
BIT 6 . . . 1
MASTER LSB OUT
PORT DATA
NOTES:
1. SS output mode (DDS7 = 1, SSOE = 1).
2. LSBF = 0. For LSBF = 1, bit order is LSB, bit 1, ..., bit 6, MSB.
Figure A-17. SPI Master Timing (CPHA = 1)
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
277
Appendix A Electrical Characteristics
SS
(INPUT)
1
12
11
11
12
3
SCK
(CPOL = 0)
(INPUT)
2
4
4
SCK
(CPOL = 1)
(INPUT)
8
7
MISO
(OUTPUT)
9
SLAVE
MSB OUT
BIT 6 . . . 1
SLAVE LSB OUT
SEE
NOTE
6
5
MOSI
(INPUT)
10
10
BIT 6 . . . 1
MSB IN
LSB IN
NOTE:
1. Not defined but normally MSB of character just received
Figure A-18. SPI Slave Timing (CPHA = 0)
SS
(INPUT)
1
3
2
12
11
11
12
SCK
(CPOL = 0)
(INPUT)
4
4
SCK
(CPOL = 1)
(INPUT)
9
MISO
(OUTPUT)
SEE
NOTE
7
MOSI
(INPUT)
10
SLAVE
MSB OUT
5
BIT 6 . . . 1
8
SLAVE LSB OUT
6
MSB IN
BIT 6 . . . 1
LSB IN
NOTE:
1. Not defined but normally LSB of character just received
Figure A-19. SPI Slave Timing (CPHA = 1)
MC9S08GB/GT Data Sheet, Rev. 2.3
278
Freescale Semiconductor
FLASH Specifications
A.10
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-13. FLASH Characteristics
Characteristic
Symbol
Min
Supply voltage for program/erase
Vprog/erase
Supply voltage for read operation
0 < fBus < 8 MHz
0 < fBus < 20 MHz
Max
Unit
2.1
3.6
V
VRead
1.8
2.08
3.6
3.6
V
Internal FCLK frequency1
fFCLK
150
200
kHz
Internal FCLK period (1/FCLK)
tFcyc
5
6.67
µs
Byte program time (random location)(2)
tprog
9
tFcyc
Byte program time (burst mode)(2)
tBurst
4
tFcyc
Page erase time2
tPage
4000
tFcyc
Mass erase time(2)
tMass
20,000
tFcyc
Program/erase endurance3
TL to TH = –40°C to + 85°C
T = 25°C
Data retention4
Typical
10,000
tD_ret
—
—
cycles
100,000
100
—
years
15
1
The frequency of this clock is controlled by a software setting.
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.
3 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/D, Typical Endurance for Nonvolatile Memory.
4 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/D, Typical Data Retention for
Nonvolatile Memory.
2
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
279
Appendix A Electrical Characteristics
MC9S08GB/GT Data Sheet, Rev. 2.3
280
Freescale Semiconductor
Appendix B Ordering Information and Mechanical
Drawings
B.1
Ordering Information
This section contains ordering numbers for MC9S08GB60, MC9S08GB32, MC9S08GT60,
MC9S08GT32, and MC9S08GT16 devices. See below for an example of the device numbering system.
Table B-1. Device Numbering System
RAM
TPM
MC9S08GB60
60K
4K
One 3-channel and one
5-channel 16-bit timer
64 LQFP (FU)
MC9S08GB32
32K
2K
One 3-channel and one
5-channel 16-bit timer
64 LQFP (FU)
MC9S08GT60
60K
4K
Two 2-channel/16-bit timers
48 QFN (FD)1
44 QFP (FB)
42 SDIP (B)
MC9S08GT32
32K
2K
Two 2-channel/16-bit timers
48 QFN (FD)(1)
44 QFP (FB)
42 SDIP (B)
MC9S08GT16
16K
1K
Two 2-channel/16-bit timers
48 QFN (FD)(1)
44 QFP (FB)
42 SDIP (B)
MC Order Number
1
Available
Package Type
(Part Number
Suffix)
FLASH
Memory
The 48-pin QFN package has one 3-channel and one 2-channel 16-bit TPM.
Temperature and package designators:
C = –40°C to 85°C
FU = 64-pin Low Quad Flat Package (LQFP)
FD = 48-pin Quad Flat Package, No Leads
FB = 44-pin Quad Flat Package (QFP)
B = 42-pin Skinny Dual In-Line Package (SDIP)
MC = Fully qualified
MC 9 S08 GB60 C XX
Package designator
Status
Memory
Temperature range
Core
Family
B.2
Mechanical Drawings
This appendix contains mechanical specifications for MC9S08GB/GT MCU.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
281
Appendix B Ordering Information and Mechanical Drawings
B.3
64-Pin LQFP Package Drawing
4X
4X 16 TIPS
0.2 H A-B D
0.2 C A-B D
A2
0.05
S
49
64
(S)
1
48
2X R R1
q1
A
0.25
B
q
E
E1
(L2)
A1
3X
E1/2
VIEW Y
16
E/2
NOTES:
33
17
D
D1
D
4X
A
( q 2)
0.08 C
C
4X
SEATING
PLANE
L
(L1)
VIEW AA
1. DIMENSIONS AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE DATUM H IS LOCATED AT BOTTOM
OF LEAD AND IS COINCIDENT WITH THE LEAD
WHERE THE LEAD EXITS THE PLASTIC BODY AT
THE BOTTOM OF THE PARTING LINE.
4. DATUMS A, B AND D TO BE DETERMINED AT DATUM
PLANE DATUM C.
5. DIMENSIONS D AND E TO BE DETERMINED AT
SEATING PLANE DATUM C.
6. DIMENSIONS D1 AND E1 DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25
PER SIDE.
7. DIMENSION b DOES NOT INCLUDE DAMBAR
PROTRUSION. DAMBAR PROTRUSION SHALL NOT
CAUSE THE b DIMENSION TO EXCEED 0.35.
MINIMUM SPACE BETWEEN PROTRUSION AND
ADJACENT LEAD OR PROTRUSION 0.07.
32
D1/2
D/2
H
( q 3)
VIEW AA
BASE METAL
b1
X
X=A, B OR D
c1
c
CL
AB
e/2
AB
60X
VIEW Y
e
GAGE PLANE
PLATING
b
0.08
M
C A-B D
SECTION AB-AB
ROTATED 90 ° CLOCKWISE
DIM
A
A1
A2
b
b1
c
c1
D
D1
e
E
E1
L
L1
L2
R1
S
q
q1
q2
q3
MILLIMETERS
MIN
MAX
--1.60
0.05
0.15
1.35
1.45
0.17
0.27
0.17
0.23
0.09
0.20
0.09
0.16
12.00 BSC
10.00 BSC
0.50 BSC
12.00 BSC
10.00 BSC
0.45
0.75
1.00 REF
0.50 REF
0.10
0.20
0.20 REF
0 ° 7°
0°
--12 ° REF
12 ° REF
CASE 840F-02
ISSUE B
DATE 09/16/98
MC9S08GB/GT Data Sheet, Rev. 2.3
282
Freescale Semiconductor
48-Pin QFN Package Drawing
B.4
48-Pin QFN Package Drawing
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
283
Appendix B Ordering Information and Mechanical Drawings
B.5
44-Pin QFP Package Drawing
B
L
B
33
23
22
S
D
V
S
0.20 (0.008)
DETAIL A
DETAIL A
F
BASE METAL
M
H A-B
S
S
C A-B
0.20 (0.008)
B
L
-B-
0.05 (0.002) A-B
-A-
D
-A-, -B-, -D-
M
34
J
N
D
44
0.20 (0.008)
12
1
11
A
M
C A-B
S
D
S
S
D
S
0.05 (0.002) A-B
S
0.20 (0.008)
M
H A-B
M
DETAIL C
C E
-H-
DATUM
PLANE
-C-
0.01 (0.004)
H
SEATING
PLANE
G
DIM
A
B
C
D
E
F
G
H
J
K
L
M
N
Q
R
S
T
U
V
W
X
T
-H-
R
K
W
S
D
S
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M,
1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE -H- IS LOCATED AT BOTTOM OF LEAD
AND IS COINCIDENT WITH THE LEAD WHERE THE LEAD
EXITS THE PLASTIC BODY AT THE BOTTOM OF THE
PARTING LINE.
4. DATUMS -A-, -B- AND -D- TO BE DETERMINED AT DATUM
PLANE -H-.
5. DIMENSIONS S AND V TO BE DETERMINED AT SEATING
PLANE -C-.
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25 (0.010)
PER SIDE. DIMENSIONS A AND B DO INCLUDE MOLD
MISMATCH AND ARE DETERMINED AT DATUM PLANE
-H-.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL BE 0.08 (0.003) TOTAL IN EXCESS OF THE D
DIMENSION AT MAXIMUM MATERIAL CONDITION.
DAMBAR CANNOT BE LOCATED ON THE LOWER RADIUS
OR THE FOOT.
M
M
DATUM
PLANE
C A-B
SECTION B-B
-D0.20 (0.008)
M
Q
X
DETAIL C
MILLIMETERS
MIN
MAX
9.90
10.10
9.90
10.10
2.10
2.45
0.30
0.45
2.00
2.10
0.30
0.40
0.80 BSC
--0.25
0.013
0.23
0.65
0.95
8.00 REF
5°
10 °
0.13
0.17
0°
7°
0.13
0.30
12.95
13.45
0.13
--0°
--12.95
13.45
0.40
--1.6 REF
INCHES
MIN
MAX
0.390
0.398
0.390
0.398
0.083
0.096
0.012
0.018
0.079
0.083
0.012
0.016
0.031 BSC
--0.010
0.005
0.009
0.026
0.037
0.315 REF
5°
10°
0.005
0.007
0°
7°
0.005
0.012
0.510
0.530
0.005
--0°
--0.510
0.530
0.016
--0.063 REF
CASE 824A-01
ISSUE O
DATE 11/19/90
MC9S08GB/GT Data Sheet, Rev. 2.3
284
Freescale Semiconductor
42-Pin SDIP Package Drawing
B.6
42-Pin SDIP Package Drawing
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN FORMED
PARALLEL.
4. DIMENSIONS A AND B DO NOT INCLUDE MOLD FLASH.
MAXIMUM MOLD FLASH 0.25 (0.010).
-A42
22
-B1
21
DIM
A
B
C
D
F
G
H
J
K
L
M
N
L
H
C
-TSEATING
PLANE
0.25 (0.010)
N
G
F
D 42 PL
K
M
T A
S
M
J
42 PL
0.25 (0.010)
M
T B
INCHES
MIN
MAX
1.435
1.465
0.540
0.560
0.155
0.200
0.014
0.022
0.032
0.046
0.070 BSC
0.300 BSC
0.008
0.015
0.115
0.135
0.600 BSC
0
15
0.020
0.040
MILLIMETERS
MIN
MAX
36.45
37.21
13.72
14.22
3.94
5.08
0.36
0.56
0.81
1.17
1.778 BSC
7.62 BSC
0.20
0.38
2.92
3.43
15.24 BSC
0
15
0.51
1.02
S
CASE 858-01
ISSUE O
DATE 02/27/90
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
285
Appendix B Ordering Information and Mechanical Drawings
MC9S08GB/GT Data Sheet, Rev. 2.3
286
Freescale Semiconductor
Data Sheet End Sheet
need need more than 13 words type on blank page or will turn page landscape in pdf file??
turned white so this would not show up on customer page.
MC9S08GB/GT Data Sheet, Rev. 2.3
Freescale Semiconductor
287
FINAL PAGE OF
288
PAGES
MC9S08GB/GT Data Sheet, Rev. 2.3
288
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MC9S08GB60
Rev. 2.3, 12/2004
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