HCS08 Family Reference Manual

HCS08 Family
Reference Manual
M68HCS08
Microcontrollers
HCS08RMv1/D
Rev. 2
05/2007
freescale.com
List of Chapters
Chapter 1 General Information and Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Chapter 2 Pins and Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Chapter 3 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Chapter 4 On-Chip Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chapter 5 Resets and Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Chapter 6 Central Processor Unit (CPU). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Chapter 7 Development Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Appendix A Instruction Set Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Appendix B Equate File Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
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List of Chapters
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Table of Contents
Chapter 1
General Information and Block Diagram
1.1
1.2
1.3
1.4
1.4.1
1.4.2
1.5
Introduction to the HCS08 Family of Microcontrollers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Programmer’s Model for the HCS08 CPU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Peripheral Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features of the MC9S08GB60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standard Features of the HCS08 Family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features of MC9S08GB60 MCU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Block Diagram of the MC9S08GB60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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16
16
17
17
17
17
Chapter 2
Pins and Connections
2.1
2.2
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended System Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MC9S08GB60 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Background/Mode Select (BKGD/MS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General-Purpose I/O and Peripheral Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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19
21
21
22
22
Chapter 3
Modes of Operation
3.1
3.2
3.3
3.4
3.5
3.6
3.6.1
3.6.2
3.6.3
3.6.4
3.6.5
3.6.6
3.6.7
3.6.8
3.6.9
3.6.10
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Run Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Active Background Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stop Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stop1 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stop2 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stop3 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Active BDM Enabled in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OSCSTEN Bit Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LVD Enabled in Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On-Chip Peripheral Modules in Stop Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Options Register (SOPT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Power Management Status and Control 1 Register (SPMSC1) . . . . . . . . . . . . . . .
System Power Management Status and Control 2 Register (SPMSC2) . . . . . . . . . . . . . . .
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Chapter 4
On-Chip Memory
4.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2
HCS08 Core-Defined Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.1
HCS08 Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.2
MC9S08GB60 Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.3
Reset and Interrupt Vector Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3
Register Addresses and Bit Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.4
RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5
60-Kbyte FLASH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.2
Program, Erase, and Blank Check Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.3
Command Timing and Burst Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.3.1
Rows and FLASH Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.3.2
Program Command Timing Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.4
Access Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.5
Vector Redirection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.6
FLASH Block Protection (MC9S08GB60) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6
Security (MC9S08GB60) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7
FLASH Registers and Control Bits (MC9S08GB60) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.1
FLASH Clock Divider Register (FCDIV). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.2
FLASH Options Register (FOPT and NVFOPT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.3
FLASH Configuration Register (FCNFG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.4
FLASH Protection Register (FPROT and NVFPROT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.5
FLASH Status Register (FSTAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.6
FLASH Command Register (FCMD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8
FLASH Application Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8.1
Initialization of the FLASH Module Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8.2
Erase One 512-Byte Page in FLASH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8.3
DoOnStack Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8.4
SpSub Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.8.5
Program One Byte of FLASH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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37
37
38
39
41
46
46
47
47
49
49
49
50
51
51
51
53
53
54
55
56
57
58
58
59
60
61
63
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Chapter 5
Resets and Interrupts
5.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2
Reset and Interrupt Features for MC9S08GB60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3
MCU Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4
Computer Operating Properly (COP) Watchdog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.1
Interrupt Stack Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.2
External Interrupt Request (IRQ) Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.2.1
Pin Configuration Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.2.2
Edge and Level Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.5.3
Interrupt Vectors, Sources, and Local Masks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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5.6
5.6.1
5.6.2
5.6.3
5.6.4
5.7
5.8
5.8.1
5.8.2
5.8.3
5.8.4
5.8.5
5.8.6
5.8.7
5.8.8
Low-Voltage Detect (LVD) System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-On Reset Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LVD Reset Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LVD Interrupt Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Low-Voltage Warning (LVW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Real-Time Interrupt (RTI). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset, Interrupt, and System Control Registers and Control Bits . . . . . . . . . . . . . . . . . . . . . . .
Interrupt Request Status and Control Register (IRQSC) . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Reset Status Register (SRS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Background Debug Force Reset Register (SBDFR). . . . . . . . . . . . . . . . . . . . . . . .
System Options Register (SOPT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Device Identification Register (SDIDH, SDIDL) . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Real-Time Interrupt Status and Control Register (SRTISC) . . . . . . . . . . . . . . . . . .
System Power Management Status and Control 1 Register (SPMSC1) . . . . . . . . . . . . . . .
System Power Management Status and Control 2 Register (SPMSC2) . . . . . . . . . . . . . . .
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Chapter 6
Central Processor Unit (CPU)
6.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2
Programmer’s Model and CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.1
Accumulator (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.2
Index Register (H:X). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.3
Stack Pointer (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.4
Program Counter (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.5
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3
Addressing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.1
Inherent Addressing Mode (INH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.2
Relative Addressing Mode (REL). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.3
Immediate Addressing Mode (IMM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.4
Direct Addressing Mode (DIR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.5
Extended Addressing Mode (EXT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6
Indexed Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.1
Indexed, No Offset (IX). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.2
Indexed, No Offset with Post Increment (IX+) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.3
Indexed, 8-Bit Offset (IX1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.4
Indexed, 8-Bit Offset with Post Increment (IX1+) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.5
Indexed, 16-Bit Offset (IX2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.6
SP-Relative, 8-Bit Offset (SP1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.3.6.7
SP-Relative, 16-Bit Offset (SP2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4
Special Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.1
Reset Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.2
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.3
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.4
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.5
Active Background Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.6
User’s View of a Bus Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Table of Contents
6.5
Instruction Set Description by Instruction Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.5.1
Data Movement Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
6.5.1.1
Loads and Stores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
6.5.1.2
Bit Set and Bit Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
6.5.1.3
Memory-to-Memory Moves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.5.1.4
Register Transfers and Nibble Swap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.5.2
Math Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.5.2.1
Add, Subtract, Multiply, and Divide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6.5.2.2
Increment, Decrement, Clear, and Negate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.5.2.3
Compare and Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.5.2.4
BCD Arithmetic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
6.5.3
Logical Operation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
6.5.3.1
AND, OR, Exclusive-OR, and Complement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
6.5.3.2
BIT Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.5.4
Shift and Rotate Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.5.5
Jump, Branch, and Loop Control Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
6.5.5.1
Unconditional Jump and Branch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
6.5.5.2
Simple Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
6.5.5.3
Signed Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.5.5.4
Unsigned Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.5.5.5
Bit Condition Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.5.5.6
Loop Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
6.5.6
Stack-Related Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
6.5.7
Miscellaneous Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
6.6
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.7
Assembly Language Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
6.7.1
Parts of a Listing Line. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
6.7.2
Assembler Directives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
6.7.2.1
BASE — Set Default Number Base for Assembler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
6.7.2.2
INCLUDE — Specify Additional Source Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
6.7.2.3
NOLIST/LIST — Turn Off or Turn On Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
6.7.2.4
ORG — Set Program Starting Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
6.7.2.5
EQU — Equate a Label to a Value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
6.7.2.6
dc.b — Define Byte-Sized Constants in Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
6.7.2.7
dc.w — Define 16-Bit (Word) Constants in Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
6.7.2.8
ds.b — Define Storage (Reserve) Memory Bytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
6.7.3
Labels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
6.7.4
Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
6.7.5
Equate File Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
6.7.6
Object Code (S19) Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Chapter 7
Development Support
7.1
7.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
HCS08 Family Reference Manual, Rev. 2
8
Freescale Semiconductor
7.3
Background Debug Controller (BDC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.1
BKGD Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.2
Communication Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.2.1
BDC Communication Speed Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.2.2
Bit Timing Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.3
BDC Registers and Control Bits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.3.1
BDC Status and Control Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.3.2
BDC Breakpoint Match Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4
BDC Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.1
SYNC — Request Timed Reference Pulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.2
ACK_ENABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.3
ACK_DISABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.4
BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.5
READ_STATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.6
WRITE_CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.7
READ_BYTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.8
READ_BYTE_WS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.9
READ_LAST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.10
WRITE_BYTE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.11
WRITE_BYTE_WS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.12
READ_BKPT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.13
WRITE_BKPT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.14
GO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.15
TRACE1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.16
TAGGO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.17
READ_A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.18
READ_CCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.19
READ_PC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.20
READ_HX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.21
READ_SP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.22
READ_NEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.23
READ_NEXT_WS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.24
WRITE_A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.25
WRITE_CCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.26
WRITE_PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.27
WRITE_HX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.28
WRITE_SP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.29
WRITE_NEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.4.30
WRITE_NEXT_WS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.5
Serial Interface Hardware Handshake Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.6
Hardware Handshake Abort Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.7
BDC Hardware Breakpoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8
Differences from M68HC12 BDM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8.1
8-Bit Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8.2
Command Formats. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8.3
Read and Write with Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8.4
BDM Versus Stop and Wait Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8.5
SYNC Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.3.8.6
Hardware Breakpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
146
147
148
149
149
151
152
153
153
155
156
156
157
157
158
159
159
160
160
160
161
161
162
162
162
163
163
163
164
164
164
165
165
166
166
166
166
167
167
168
170
173
173
174
174
174
175
175
175
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
9
Table of Contents
7.4
Part Identification and BDC Force Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.4.1
System Device Identification Registers (SDIDH:SDIDL) . . . . . . . . . . . . . . . . . . . . . . . . . .
7.4.2
System Background Debug Force Reset Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5
On-Chip Debug System (DBG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.1
Comparators A and B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.2
Bus Capture Information and FIFO Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.3
Change-of-Flow information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.4
Tag vs. Force Breakpoints and Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.5
CPU Breakpoint Requests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6
Trigger Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.1
A-Only Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.2
A OR B Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.3
A Then B Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.4
Event-Only B Trigger (Store Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.5
A Then Event-Only B Trigger (Store Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.6
A AND B Data Trigger (Full Mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.7
A AND NOT B Data Trigger (Full Mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.8
Inside Range Trigger: A ≤ Address ≤ B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.6.9
Outside Range Trigger: Address < A or Address > B. . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7
DBG Registers and Control Bits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.1
Debug Comparator A High Register (DBGCAH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.2
Debug Comparator A Low Register (DBGCAL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.3
Debug Comparator B High Register (DBGCBH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.4
Debug Comparator B Low Register (DBGCBL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.5
Debug FIFO High Register (DBGFH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.6
Debug FIFO Low Register (DBGFL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.7
Debug Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.8
Debug Trigger Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.7.9
Debug Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.8
Application Information and Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.8.1
Orientation to the Debugger Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.8.2
Example 1: Stop Execution at Address A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5.8.3
Example 2: Stop Execution at the Instruction at Address A . . . . . . . . . . . . . . . . . . . . . .
7.5.8.4
Example 3: Stop Execution at the Instruction at Address A or Address B . . . . . . . . . . .
7.5.8.5
Example 4: Begin Trace at the Instruction at Address A . . . . . . . . . . . . . . . . . . . . . . . .
7.5.8.6
Example 5: End Trace to Stop After A-Then-B Sequence . . . . . . . . . . . . . . . . . . . . . . .
7.5.8.7
Example 6: Begin Trace On Write of Data B to Address A . . . . . . . . . . . . . . . . . . . . . .
7.5.8.8
Example 7: Capture the First Eight Values Read From Address B . . . . . . . . . . . . . . . .
7.5.8.9
Example 8: Capture Values Written to Address B After Address A Read . . . . . . . . . . .
7.5.8.10
Example 9: Trigger On Any Execution Within a Routine . . . . . . . . . . . . . . . . . . . . . . . .
7.5.8.11
Example 10: Trigger On Any Attempt To Execute Outside FLASH . . . . . . . . . . . . . . . .
7.5.9
Hardware Breakpoints and ROM Patching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
176
176
177
177
177
178
179
180
180
180
181
181
181
181
182
182
182
182
182
183
183
183
183
183
183
184
184
186
187
188
189
190
190
191
191
192
192
193
193
194
194
194
Appendix A
Instruction Set Details
A.1
A.2
A.3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Convention Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
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A.4
Instruction Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADC
Add with Carry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADD
Add without Carry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AIS
Add Immediate Value (Signed) to Stack Pointer . . . . . . . . . . . . . . . . . . . . . . .
AIX
Add Immediate Value (Signed) to Index Register . . . . . . . . . . . . . . . . . . . . . .
AND
Logical AND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ASL
Arithmetic Shift Left . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ASR
Arithmetic Shift Right . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCC
Branch if Carry Bit Clear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCLR n Clear Bit n in Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BCS
Branch if Carry Bit Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BEQ
Branch if Equal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BGE
Branch if Greater Than or Equal To . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BGND
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BGT
Branch if Greater Than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BHCC
Branch if Half Carry Bit Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BHCS
Branch if Half Carry Bit Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BHI
Branch if Higher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BHS
Branch if Higher or Same . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BIH
Branch if IRQ Pin High . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BIL
Branch if IRQ Pin Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BIT
Bit Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BLE
Branch if Less Than or Equal To . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BLO
Branch if Lower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BLS
Branch if Lower or Same . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BLT
Branch if Less Than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BMC
Branch if Interrupt Mask Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BMI
Branch if Minus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BMS
Branch if Interrupt Mask Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BNE
Branch if Not Equal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BPL
Branch if Plus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BRA
Branch Always . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BRCLR n Branch if Bit n in Memory Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BRN
Branch Never . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BRSET n Branch if Bit n in Memory Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BSET n Set Bit n in Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BSR
Branch to Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CBEQ
Compare and Branch if Equal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CLC
Clear Carry Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CLI
Clear Interrupt Mask Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CLR
Clear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CMP
Compare Accumulator with Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COM
Complement (One’s Complement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CPHX
Compare Index Register with Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CPX
Compare X (Index Register Low) with Memory . . . . . . . . . . . . . . . . . . . . . . . .
DAA
Decimal Adjust Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
233
234
235
236
237
238
239
240
241
242
243
244
245
246
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Freescale Semiconductor
11
Table of Contents
DBNZ
DEC
DIV
EOR
INC
JMP
JSR
LDA
LDHX
LDX
LSL
LSR
MOV
MUL
NEG
NOP
NSA
ORA
PSHA
PSHH
PSHX
PULA
PULH
PULX
ROL
ROR
RSP
RTI
RTS
SBC
SEC
SEI
STA
STHX
STOP
STX
SUB
SWI
TAP
TAX
TPA
TST
TSX
TXA
TXS
WAIT
Decrement and Branch if Not Zero. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Decrement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Divide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exclusive-OR Memory with Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Increment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Jump to Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Load Accumulator from Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Load Index Register from Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Load X (Index Register Low) from Memory . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logical Shift Left. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logical Shift Right . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pull Accumulator from Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pull H (Index Register High) from Stack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pull X (Index Register Low) from Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rotate Left through Carry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rotate Right through Carry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Return from Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Return from Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Subtract with Carry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Set Carry Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Set Interrupt Mask Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Store Accumulator in Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Store Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable IRQ Pin, Stop Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Store X (Index Register Low) in Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Subtract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Software Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Accumulator to Processor Status Byte . . . . . . . . . . . . . . . . . . . . . . .
Transfer Accumulator to X (Index Register Low) . . . . . . . . . . . . . . . . . . . . . .
Transfer Processor Status Byte to Accumulator . . . . . . . . . . . . . . . . . . . . . . .
Test for Negative or Zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer Stack Pointer to Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transfer X (Index Register Low) to Accumulator . . . . . . . . . . . . . . . . . . . . . . .
Transfer Index Register to Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enable Interrupts; Stop Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Appendix B
Equate File Conventions
B.1
B.2
B.3
B.4
B.5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Memory Map Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vector Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bits Defined in Two Ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Complete Equate File for MC9S08GB60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
295
296
296
297
298
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13
Table of Contents
HCS08 Family Reference Manual, Rev. 2
14
Freescale Semiconductor
Chapter 1
General Information and Block Diagram
1.1 Introduction to the HCS08 Family of Microcontrollers
Freescale’s new HCS08 Family of microcontrollers, while containing new instructions to implement rapid
debugging and development, is still fully compatible with all legacy code written for the M68HC08 Family.
This reference manual uses the MC9S08GB60, the first HCS08 Family member, for describing
applications and module behavior. When working with another HCS08 Family MCU, refer to the device
data sheet for information specific to that MCU.
Each MCU device in the HCS08 Family consists of the HCS08 core plus several memory and peripheral
modules. The HCS08 core consists of:
• HCS08 CPU
• Background debug controller (BDC)
• Support for up to 32 interrupt/reset sources
• Chip-level address decode
The HCS08 CPU executes all HC08 instructions, as well as a background (BGND) instruction and
additional addressing modes on the LDHX, STHX, and CPHX instructions to improve compiler efficiency.
The maximum clock speed for the CPU is 40 MHz (typically generated from a crystal or internal clock
generator). The CPU performs operations at this 40 MHz rate and the maximum bus rate is 20 MHz (half
the CPU clock frequency). See Chapter 6 Central Processor Unit (CPU) for more information.
The background debug controller (BDC) is built into the CPU core to allow easier access to address
generation circuits and CPU register information. The BDC includes one hardware breakpoint. Other
more sophisticated breakpoints are normally included in the separate on-chip debug module. The BDC
allows access to internal register and memory locations via a single pin on the MCU. See Chapter 7
Development Support for more information.
The core includes support for up to 32 interrupt or reset sources with separate vectors. The peripheral
modules provide local interrupt enable circuitry and flag registers. See Chapter 5 Resets and Interrupts
for more information.
Although the exact memory map for each derivative is different, some basic aspects are controlled by
decode logic in the HCS08 core which is not expected to change from one HCS08 derivative to another.
The registers for input/output (I/O) ports and most control and status registers for peripheral modules are
located starting at $0000 and extending for 32, 64, 96, or 128 bytes. The space from the end of these
direct page registers to $107F is reserved for static RAM memory. A space starting at $1800 is reserved
for high-page registers. These are status and control registers that do not need to be accessed as often
as the direct page registers. For example, system setup registers that are written only once after reset
may be located in this high-register space to make more room in the direct addressing space for registers
and RAM. The remaining space from $1C00 through $FFFF is reserved for FLASH or ROM memory. The
last 64 locations ($FFC0–$FFFF) are further classified as vector space (for up to 32 interrupt and reset
vectors).
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
15
General Information and Block Diagram
1.2 Programmer’s Model for the HCS08 CPU
The programmer’s model for the HCS08 CPU shown in Figure 1-1 includes the same registers as the
M68HC08. These include one 8-bit accumulator (A), a 16-bit index register made up of separately
accessible upper (H) and lower (X) 8-bit halves, a 16-bit stack pointer (SP), a 16-bit program counter (PC)
and an 8-bit condition code register (CCR) which includes five processor status flags (V, H, N, Z, and C)
and the global interrupt mask (I).
7
0
ACCUMULATOR
A
16-BIT INDEX REGISTER H:X
H INDEX REGISTER (HIGH)
15
8
INDEX REGISTER (LOW)
7
X
0
SP
STACK POINTER
0
15
PROGRAM COUNTER
7
0
CONDITION CODE REGISTER V 1 1 H I N Z C
PC
CCR
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
Figure 1-1. CPU Registers
1.3 Peripheral Modules
The combination of peripheral modules included on a specific derivative can vary widely, however there
will always be memory for programs and data, and there will always be a clock module and debug module.
Some of the peripheral modules in the HCS08 Family include:
• 4K–60K byte FLASH or ROM memory
• 128–4K byte Static RAM
• Asynchronous serial I/O (SCI)
• Synchronous serial I/O (SPI and IIC)
• Timer/PWM modules (TPM)
• Keyboard interrupts (KBI)
• Analog to digital converter (ADC)
• Clock generation modules
– Full-featured internal clock generator (ICG) capable of operation with no external components
(frequency multiplication is accomplished with a frequency-locked loop (FLL) that does not use
any external filter components)
– Traditional Pierce oscillator with no FLL or PLL (OSC)
• Debug module with nine trigger modes and bus capture FIFO (DBG)
Always refer to the appropriate data sheet for more specific information about the features in each HCS08
derivative MCU.
HCS08 Family Reference Manual, Rev. 2
16
Freescale Semiconductor
Features of the MC9S08GB60
1.4 Features of the MC9S08GB60
The first device in the HCS08 Family is the MC9S08GB60 which is presented here as a representative
example of a derivative HCS08 MCU.
1.4.1 Standard Features of the HCS08 Family
•
•
•
•
•
•
•
•
40-MHz HCS08 CPU (central processor unit)
HC08 instruction set with added BGND instruction
Background debugging system
Breakpoint capability to allow single breakpoint setting during
in-circuit debugging (plus two more breakpoints in on-chip debug module)
Debug module containing two comparators and nine trigger modes. Eight deep FIFO for storing
change-of-flow addresses and event-only data. Debug module supports both tag and force
breakpoints.
Support for up to 32 interrupt/reset sources
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)
1.4.2 Features of MC9S08GB60 MCU
•
•
•
•
•
•
•
•
•
•
•
•
•
•
60K on-chip in-circuit programmable FLASH memory with block protection and security options
4K on-chip random-access memory (RAM)
8-channel, 10-bit analog-to-digital converter (ATD)
Two serial communications interface modules (SCI)
Serial peripheral interface module (SPI)
Clock source options include crystal, resonator, external clock or internally generated clock with
precision NVM trimming
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
56 general-purpose input/output (I/O) pins, depending on package selection
64-pin low-profile quad flat package (LQFP)
1.5 Block Diagram of the MC9S08GB60
Figure 1-2 is an overall block diagram of the MC9S08GB60 MCU showing all major peripheral systems
and all device pins. The MC9S08GB60 is a representative device in the HCS08 Family.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
17
General Information and Block Diagram
INTERNAL BUS
IRQ
NOTES 2, 3
RESETS AND INTERRUPTS
MODES OF OPERATION
POWER MANAGEMENT
PORT A
HCS08 SYSTEM CONTROL
8
8-BIT KEYBOARD
INTERRUPT MODULE (KBI)
PORT B
RESET
NOTE 4
BKP
DEBUG
MODULE (DBG)
8
COP
IRQ
LVD
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI1)
USER RAM
(GB60 = 4096 BYTES)
(GB32 = 2048 BYTES)
VDDAD
VSSAD
VREFH
VREFL
10-BIT
ANALOG-TO-DIGITAL
CONVERTER (ATD)
INTERNAL CLOCK
GENERATOR (ICG)
SERIAL COMMUNICATIONS
INTERFACE MODULE (SCI2)
VSS
PTF7–PTF0
NOTES 1, 5
VOLTAGE
REGULATOR
PORT G
VDD
NOTE 1
SERIAL PERIPHERAL
INTERFACE MODULE (SPI)
LOW-POWER OSCILLATOR
NOTE 1
PTE7
PTE6
PTE5/SPSCK
PTE4/MOSI
PTE3/MISO
PTE2/SS
PTE1/RxD1
PTE0/TxD1
3-CHANNEL TIMER/PWM
MODULE (TPM1)
5-CHANNEL TIMER/PWM
MODULE (TPM2)
PTB7/AD7–
PTB0/AD0
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)
NOTES 1, 6
PTC7
PTC6
PTC5
PTC4
PTC3/SCL
PTC2/SDA
PTC1/RxD2
PTC0/TxD2
IIC MODULE (IIC)
RTI
PTA7/KBIP7–
PTA0/KBIP0
PORT C
BDC
INT
PORT D
CPU
PORT E
HCS08 CORE
8
PTG7
PTG6
PTG5
PTG4
PTG3
PTG2/EXTAL
PTG1/XTAL
PTG0/BKGD/MS
NOTES 1, 5
NOTE 1
NOTE 1
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 software configurable pullup/pulldown device.
Figure 1-2. MC9S08GB60 Block Diagram
HCS08 Family Reference Manual, Rev. 2
18
Freescale Semiconductor
Chapter 2
Pins and Connections
2.1 Introduction
This section shows basic connections that are common to typical application systems. Additional details
are provided for power, oscillator, reset, mode, and background interface connections. The example
system uses the MC9S08GB60, which is a representative device in the HCS08 Family.
On-chip peripheral systems share pins so that when a peripheral system is not using a pin or pins, those
pins may be used as general-purpose input/output (I/O) pins. When planning system connections, the
designer should consider the reset condition of these pins, as well as the characteristics of the pins after
software has configured them for their application purpose.
For example, a serial TxD pin would have the characteristics of an actively driven CMOS output after the
SCI transmitter is enabled. However, between reset and when application software enables the SCI
transmitter, the pin will have the characteristics of a high-impedance input. Although floating CMOS inputs
are generally considered undesirable, the delay from reset until the pins are reconfigured for other
functions is so short that this is almost never a serious concern in most applications. If this is determined
to be a problem, the user may need to connect an external pullup resistor to such pins.
2.2 Recommended System Connections
Figure 2-1 shows pin connections that are common to most typical HCS08 application systems. This
particular example shows the MC9S08GB60 because it is a representative device in the HCS08 Family.
Always refer to the data sheet for a specific derivative to find detailed information about unusual pins.
A more detailed discussion of system connections follows.
2.2.1 Power
VDD and VSS are the primary power supply pins for the HCS08 MCU. This voltage source supplies power
to all I/O buffer circuitry and to an internal voltage regulator. This internal voltage regulator provides
regulated 2.5-volt (nominal) power 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.
Due to the sub-micron process used, internal logic in the HCS08 MCU uses a lower power supply voltage
than earlier MCUs. In addition to allowing the smaller layout geometry, this also has the benefit of lowering
overall system power requirements. This implies that an on-chip voltage regulator is used to step down
the voltage from the external MCU supply voltage to the internal logic voltage.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
19
Pins and Connections
VREFH
CBYAD
0.1 μF
+
3V
CBLK
10 μF
9S08GB60
PTA0/KBIP0
VSSAD
VREFL
VDD
VDD
SYSTEM
POWER
VDDAD
+
CBY
0.1 μF
PTA1/KBIP1
PTA2/KBIP2
PORT
A
PTA3/KBIP3
PTA4/KBIP4
PTA5/KBIP5
VSS
PTA6/KBIP6
PTA7/KBIP7
NOTE 1
RF
C2
RS
C1
X1
PTB0/AD0
XTAL
NOTE 2
PTB1/AD1
PTB2/AD2
EXTAL
NOTE 2
PORT
B
PTB4/AD4
PTB5/AD5
BACKGROUND HEADER
1
VDD
PTB3/AD3
BKGD/MS
NOTE 3
PTB6/AD6
I/O AND
PTB7/AD7
PERIPHERAL
PTC0/TxD2
INTERFACE TO
PTC1/RxD2
APPLICATION
PTC2/SDA
RESET
OPTIONAL
MANUAL
RESET
PORT
C
PTC3/SCL
SYSTEM
PTC4
PTC5
ASYNCHRONOUS
INTERRUPT
INPUT
PTC6
IRQ
PTC7
PTG0/BKDG/MS
PTD0/TPM1CH0
PTG1/XTAL
PTD1/TPM1CH1
PTD2/TPM1CH2
PTG2/EXTAL
PTG3
PTG4
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.
PORT
G
PORT
D
PTD3/TPM2CH0
PTD4/TPM2CH1
PTG5
PTD5/TPM2CH2
PTG6
PTD6/TPM2CH3
PTG7
PTD7/TPM2CH4
PTF0
PTE0/TxD1
PTF1
PTE1/RxD1
PTF2
PTE2/SS
PTF3
PTF4
PORT
F
PORT
E
PTE3/MISO
PTE4/MOSI
PTF5
PTE5/SPSCK
PTF6
PTE6
PTF7
PTE7
Figure 2-1. Basic System Connections
HCS08 Family Reference Manual, Rev. 2
20
Freescale Semiconductor
Recommended System Connections
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.
2.2.2 MC9S08GB60 Oscillator
This section describes the oscillator in the MC9S08GB60. Not all HCS08 derivatives use the same type
of oscillator; some have no external oscillator components. Always refer to the data sheet for a particular
HCS08 derivative for more details.
The MC9S08GB60 can be operated with no external crystal or oscillator. When this occurs, the MCU uses
an internally generated self-clocked rate equivalent to about 8-MHz crystal rate. This frequency source is
used during reset startup to avoid the need for a long crystal startup delay.
The oscillator in the MC9S08GB60 is a traditional 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.
The low range is 32 kHz to 100 kHz and the high range is 1 MHz to 16 MHz.
Rather than a crystal or ceramic resonator, an external oscillator with a frequency up to 40 MHz can be
connected to the EXTAL input pin and the XTAL output pin must be left unconnected.
Refer to Figure 2-1 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).
Normally, RS is used for the 32-kHz to 100-kHz range. Use up to 10 kΩ or consult the crystal manufacturer
for recommendations. RS is not normally needed for the 1-MHz to 16-MHz range and may be replaced
with a direct connection.
2.2.3 Reset
Not all HCS08 derivatives have a reset pin. When there is no reset pin, you can cause a reset by cycling
power to force power-on reset (POR), using a background command to write to the BDFR bit in the
SBDFR register, or using software to force something like an illegal opcode reset.
In the MC9S08GB60, the reset pin is a dedicated pin with a pullup device built in. It has input hysteresis,
a 10-mA 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 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).
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
21
Pins and Connections
Whenever any reset is initiated (whether from an external signal or from an internal system), the reset pin
is driven low for about 4.25 μs, released, and sampled again about 4.75 μs 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 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.
2.2.4 Background/Mode Select (BKGD/MS)
The background/mode select (BKGD/MS) pin includes an internal pullup device, input hysteresis, a 2-mA
output driver, and no output slew rate control. If nothing is connected to this pin, the MCU will enter normal
operating mode at the rising edge of reset. If a debug system is connected to the 6-pin standard
background debug header, it can hold BKGD/MS low during the rising edge of reset which forces the MCU
to active background mode.
The BKGD pin is used primarily for background debug controller (BDC) communications using a custom
protocol that uses 16 clock cycles of the target MCU’s BDC clock per bit time. The target MCU’s BDC
clock could be as fast as the 20-MHz 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.
2.2.5 General-Purpose I/O and Peripheral Ports
Fifty-six pins on the MC9S08GB60 are shared among general-purpose I/O and on-chip peripheral
functions such as timers and serial I/O systems. Immediately after reset, all 56 of these pins except
PTG0/BKGD/MS are configured as high-impedance general-purpose inputs with internal pullup devices
disabled. 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 or, for information about how and
when on-chip peripheral systems use these pins, refer to the appropriate section from the data sheet for
a particular derivative.
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.
Pullup enable bits for each of the 56 I/O pins control whether on-chip pullup or pulldown devices are
enabled whenever the pin is acting as an input even if it is being controlled by an on-chip peripheral
module. Sometimes a pulldown resistor is substituted for the pullup resistor based on control bits, as in
the MC9S08GB60 keyboard interrupt pins and IRQ pin. When the PTA7–PTA4 pins are controlled by the
KBI module in the MC9S08GB60 and are configured for rising-edge/high-level sensitivity, the pullup
enable control bits enable pulldown devices rather than pullup devices. Similarly, when the IRQ input in
HCS08 Family Reference Manual, Rev. 2
22
Freescale Semiconductor
Recommended System Connections
the MC9S08GB60 and is set to detect rising edges, the pullup enable control bit enables a pulldown
device rather than a pullup device.
HCS08 outputs have software controlled slew rate. This feature allows you to effectively choose between
two output transistor sizes. When the smaller size is chosen, the output switching slew rate is slower
which can result in lower EMI noise. The larger size can be selected where speed of heavy loads are more
important.
Some HCS08 output pins have high-current drivers capable of sourcing or sinking on the order of 10 mA
each (subject to a total chip I/O current).
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
23
Pins and Connections
HCS08 Family Reference Manual, Rev. 2
24
Freescale Semiconductor
Chapter 3
Modes of Operation
3.1 Introduction
This section discusses stop and wait power-saving modes, as well as run mode versus the active
background mode. Entry into each mode, exit from each mode, and functionality while in each of the
modes are described.
An on-chip voltage regulator is a new feature of MCUs in Freescale’s HCS08 Family. The primary function
of this regulator is to produce an internal 2.5-volt logic power supply from the MCU’s VDD power supply.
This regulator has standby, passthrough, and power-down modes, which are used to place an
9S08GB/GT into stop1, stop2, and stop3 modes. These modes and the related functions and registers
are discussed in this section. Since registers and control bits may not be identical for all HCS08
derivatives, always refer to the data sheet for a specific derivative for more information.
3.2 Features
•
•
•
•
Run mode for normal user operation
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
– Separate periodic wakeup clock can stay running in stop2, stop3
– Oscillator can be left on to reduce crystal startup time in stop3
3.3 Run Mode
This is the normal operating mode for the 9S08GB/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.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
25
Modes of Operation
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
Once in active background mode, the CPU is held in a suspended state waiting for serial background
commands rather than executing instructions from the user’s application program.
Background commands are of two types:
• Non-intrusive commands, defined as commands that can be issued while the user program is
running. Non-intrusive commands can be issued through the BKGD pin while the MCU is in run
mode; non-intrusive commands can also be executed when the MCU is in the active background
mode. Non-intrusive commands include:
– Memory access commands
– Memory-access-with-status commands
– BDC register access commands
– The BACKGROUND command
• Active background commands, which can only be executed while the MCU is in active background
mode. Active background commands include commands to:
– Read or write CPU registers
– Trace one user program instruction at a time
– Leave active background mode to return to the user’s application program (GO)
The active background mode is used to program a bootloader or user application program into the FLASH
program memory before the MCU is operated in run mode for the first time. When the 9S08GB/GT is
shipped from the Freescale 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.
Users may choose to use some other communication channel such as the on-chip serial communications
interface (SCI) to erase and reprogram the FLASH memory. Typically, the user would program a
bootloader into the upper address locations of the FLASH. This bootloader could allow execution of
normal user application programs. When some special sequence of characters is received through the
SCI or some special combination of I/O signals is detected, control can be passed to the bootloader to
allow FLASH erase and programming or other debug operations.
The user decides the operation of the bootloader program because the operation is not written and
preprogrammed into the MCU by Freescale. The user is free to write this program to do anything within
the MCU’s capability. The function of this bootloader or other application programs is primarily limited by
the imagination of the programmer.
For additional information about the active background mode, refer to Chapter 7 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
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Stop Modes
resumes processing, beginning with the stacking operations leading to the interrupt service routine.
Peripheral modules can be disabled to conserve power in wait mode but a peripheral must be enabled to
be the source of an interrupt that will wake the MCU from wait.
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 the system power
management status and control 2 register (SPMSC2).
Table 3-1 summarizes the behavior of the MCU in each of the stop modes.
Table 3-1. Stop Mode Behavior
Mode
CPU, Digital
Peripherals,
FLASH
RAM
Clock
Module
ATD
KBI
Regulator
I/O Pins
RTI
Stop1
Off
Off
Off
Disabled
Off
Off
Reset
Off
Stop2
Off
Standby
Off
Disabled
Off
Standby
States
held
Optionally on
Stop3
Standby
Standby
Standby(1) Disabled
Optionally on
Standby
States
held
Optionally on
1. Crystal oscillator can be configured to run in stop3. Please see the ICG registers.
Normally, the interrupt input paths for the IRQ and keyboard interrupt inputs pass through clocked
synchronization logic. Since there are no clocks when the MCU is in stop mode, these synchronizers are
bypassed in stop mode so asynchronous inputs to IRQ for all stop modes and keyboard interrupt inputs
for stop3 can wake the MCU from stop.
Table 3-2 summarizes the configuration and exit conditions for stop1, stop2, and stop3.
Table 3-2. Stop Mode Selection and Source of Exit
SPMC2 Configuration
Mode
Condition Upon Exit(1)
Source of Exit
PDC
PPDC
Stop1
1
0
IRQ or reset
POR
Stop2
1
1
IRQ or reset, RTI
POR (PPDF bit set in SPMSCR)
Stop3
0
Don’t care
IRQ or reset, RTI, KBI
Either reset or normal operation
continues from the interrupt
vector
1. POR is valid exit in all cases.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
27
Modes of Operation
3.6.1 Stop1 Mode
Stop1 mode provides the lowest possible standby power consumption by causing the internal circuitry of
the MCU to be powered down. To select entry into stop1 mode, the PDC bit in SPMSC2 must be set and
the PPDC bit in SPMSC2 must be clear upon execution of a STOP instruction.
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 done 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
Stop2 mode provides very low standby power consumption and maintains the contents of RAM and the
current state of all of the I/O pins. To select entry into stop2, the user must execute a STOP instruction
while the PPDC and PDC bits in SPMSC2 are set.
Before entering stop2 mode, the user can save the contents of the I/O port registers, as well as any other
memory-mapped registers which they want to restore after exit of stop2, to locations in RAM. Upon exit
of stop2, these values can be restored by user software before pin driver 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 logic 1 is written to PPDACK in SPMSC2.
Exit from stop2 is done 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. When the RTI is used to cause a wakeup event, 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.
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 stop2 recovery routine. PPDF remains set and the I/O pin states remain latched until a logic 1 is
written to PPDACK in SPMSC2.
To maintain I/O state for pins that were configured as general-purpose I/O, the user must restore the
contents of the I/O port registers, which have been saved in RAM, to the port registers before writing to
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.
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Freescale Semiconductor
Stop Modes
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 stop3 mode, all of the clocks in the MCU, including the oscillator itself, are halted. The clock
module (ICG on the MC9S08GB/GT) enters its standby state, as does the voltage regulator and the ATD.
The states of all of the internal registers and logic, as well as the RAM content, are maintained. The I/O
pin states are not latched at the pin as in stop2. Instead they are maintained by virtue of the states of the
internal logic driving the pins being maintained.
Exit from stop3 is done by asserting RESET, 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 Chapter 7 Development Support of this reference manual. If ENBDM is set
when the CPU executes a STOP instruction, the system clocks to the background debug logic remain
active when the MCU enters stop mode so background debug communication is still possible. In addition,
the voltage regulator does not enter its low-power standby state but maintains full internal regulation. If
the user attempts to enter 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. Once in 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 3-3. BDM Enabled Stop Mode Behavior
Mode
Stop3
PDC
Don’t
care
PPDC
Don’t
care
CPU, Digital
Peripherals,
FLASH
Standby
RAM
Standby
Clock
Module
Active
ATD
Disabled
Regulator
Active
I/O Pins
States
held
RTI
Optionally on
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
29
Modes of Operation
3.6.5 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.
3.6.6 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 3-4. LVD Enabled Stop Mode Behavior
Mode
Stop3
PDC
Don’t
care
PPDC
Don’t
care
CPU, Digital
Peripherals,
FLASH
Standby
RAM
Standby
Clock
Module
Standby
ATD
Disabled
Regulator
Active
I/O Pins
States
held
RTI
Optionally on
3.6.7 On-Chip Peripheral Modules in Stop Modes
When the MCU enters any stop mode, system clocks to the internal peripheral modules are stopped.
Even in the exception case (ENBDM = 1), where clocks are kept alive to the background debug logic,
clocks to the peripheral systems are halted to reduce power consumption. Refer to 3.6.1 Stop1 Mode,
3.6.2 Stop2 Mode, and 3.6.3 Stop3 Mode for specific information on system behavior in stop modes. The
information provided here applies to the MC9S08GB60. Consult the device-specific data sheet for
information about another MCU.
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
The contents of the FLASH memory are non-volatile and are preserved in any of the stop modes.
• 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.
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
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
(OSCSTEN). 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. Upon exit from
stop1 or stop2, the ICG must be initialized as if from a POR. The digitally controlled oscillator (DCO) in
the ICG preserves previous frequency settings, allowing fast frequency lock when recovering from stop3
mode.
CPU — On entry to stop mode, the CPU clocks are stopped and CPU operation is halted. If the voltage
regulator was not configured to go into power-down mode and an interrupt wakes the CPU from stop,
CPU clocks are restored and the CPU resumes processing with the stacking operation leading to the
interrupt service routine. When an RTI instruction is executed to return from this interrupt, the return
address takes the CPU back to the instruction that immediately follows the STOP instruction. If the voltage
regulator was powered down or a reset was used to wake the MCU from stop mode, processing resumes
by fetching the reset vector.
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 — Take precautions to avoid going into stop mode while SCI communications are in progress. Since
clocks are stopped, any serial character that was being received or sent will be stopped, causing the
communication to fail. No SCI characters can be received while the MCU is stopped. 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 — It would be unusual to go into stop mode while SPI communications are in progress. Since clocks
are stopped, any serial transfer that was in progress will be stopped. Since the SPI is a synchronous serial
communication interface, there is no lower limit on the communication speed. Although it would be
unusual, a transfer that was in progress when the MCU went into stop3 can resume after stop. No SPI
transfers can be completed while the MCU is stopped. 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 stop. 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.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
31
Modes of Operation
3.6.8 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.
Read:
Write:
Reset:
Bit 7
6
5
COPE(1)
COPT(1)
STOPE(1)
1
1
0
4
1
3
2
0
0
0
0
1
Bit 0
BKGDPE
1
1
= Unimplemented or Reserved
1. This bit can be written only one time after reset. Additional writes are ignored.
Figure 3-1. System Options Register (SOPT)
COPE — COP Watchdog Enable
This write-once bit defaults to 1 after reset. This bit does not relate directly to modes of operation, but
is shown here because some bits in this register can be written only once 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. This bit does not relate directly to modes of operation, but
is shown here because some bits in this register can be written only once 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 PTD0/BKGD/MS pin to function as BKGD/MS. When the bit is clear, the
pin will function as PTD0, 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.
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Freescale Semiconductor
Stop Modes
3.6.9 System Power Management Status and Control 1 Register (SPMSC1)
Read:
Bit 7
6
LVDF
0
LVDACK
Write:
Reset:
0
0
5
4
3
2
LVDIE
LVDRE
LVDSE
LVDE
0
1
1
1
1
Bit 0
0
0
0
0
= Unimplemented or Reserved
Figure 3-2. 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. This bit does not
relate directly to modes of operation, but is shown here because some bits in this register can be
written only once after reset.
LVDACK — Low-Voltage Detect Acknowledge
This write-only bit is used to acknowledge low voltage detection events (write 1 to clear LVDF). Reads
always return logic 0. This bit does not relate directly to modes of operation, but is shown here because
some bits in this register can be written only once after reset.
LVDIE — Low-Voltage Detect Interrupt Enable
This read/write bit enables hardware interrupt requests for LVDF. This bit does not relate directly to
modes of operation, but is shown here because some bits in this register can be written only once after
reset.
1 = Request a hardware interrupt when LVDF = 1.
0 = Hardware interrupt disabled (use polling).
LVDRE — Low-Voltage Detect Reset Enable
This read/write bit enables LVDF events to generate a hardware reset (provided LVDE = 1). This bit
does not relate directly to modes of operation, but is shown here because some bits in this register can
be written only once after reset.
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. This bit does not relate directly to modes of operation, but is shown
here because some bits in this register can be written only once after reset.
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. This bit does not relate directly to modes of operation, but is shown here because some bits
in this register can be written only once after reset.
1 = LVD logic enabled.
0 = LVD logic disabled.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
33
Modes of Operation
3.6.10 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
LVWACK
Write:
5
4
LVDV
LVWV
3
2
PPDF
0
PPDACK
1
Bit 0
PDC
PPDC
Power-on reset:
0(1)
0
0
0
0
0
0
0
LVD reset:
0(1)
0
U
U
0
0
0
0
Any other reset:
(1)
0
U
U
0
0
0
0
0
= Unimplemented or Reserved
U = Unaffected by reset
1. LVWF will be set in the case when VSupply transitions below the trip point or after reset and VSupply
is already below VLVW.
Figure 3-3. System Power Management Status and Control 2 Register (SPMSC2)
LVWF — Low-Voltage Warning Flag
The LVWF bit indicates the low voltage warning status. This bit does not relate directly to modes of
operation, but is shown here because some bits in this register can be written only once after reset.
1 = Low voltage warning is present or was present.
0 = Low voltage warning not present.
LVWACK — Low-Voltage Warning Acknowledge
The LVWF bit indicates the low voltage warning status. This bit does not relate directly to modes of
operation, but is shown here because some bits in this register can be written only once after reset.
Writing a logic 1 to LVWACK clears LVWF to a logic 0 if a low voltage warning is not present.
LVDV — Low-Voltage Detect Voltage Select
The LVDV bit selects the LVD trip point voltage (VLVD). This bit does not relate directly to modes of
operation, but is shown here because some bits in this register can be written only once after reset.
1 = High trip point selected (for 3 V system).
0 = Low trip point selected (for 2 V system).
LVWV — Low-Voltage Warning Voltage Select
The LVWV bit selects the LVW trip point voltage (VLVW). This bit does not relate directly to modes of
operation, but is shown here because some bits in this register can be written only once after reset.
1 = High trip point selected (for 3 V system).
0 = Low trip point selected (for 2 V system).
PPDF — Partial Power Down Flag
The PPDF bit indicates that the MCU has exited stop2 mode.
1 = Stop2 mode recovery.
0 = Not stop2 mode recovery.
PPDACK — Partial Power Down Acknowledge
Writing a logic 1 to PPDACK clears the PPDF bit.
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Freescale Semiconductor
Stop Modes
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.
Table 3-5. Stop Mode Selection and Source of Exit
SPMC2 Configuration
Mode
Source of Exit
Condition Upon Exit
PDC
PPDC
Stop1
1
0
IRQ or reset
POR
Stop2
1
1
IRQ or reset, RTI
POR (PPDF bit set in SPMSCR)
Stop3
0
Don’t care
IRQ or reset,
RTI, KBI
If reset is used, then POR; else,
normal operation continues from
the interrupt vector
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
35
Modes of Operation
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Chapter 4
On-Chip Memory
4.1 Introduction
This section shows the overall 64-Kbyte memory map and then explains each major memory block in
greater detail.
• Direct-page registers, high-page registers, and nonvolatile registers are shown in tables which
provide the register names, absolute addresses, and the arrangement of control and status bits
within the registers.
• The RAM description includes information about initialization of the system stack pointer.
• The FLASH section explains programming and erase operations and block protection.
• The security section explains how internal FLASH and RAM contents can be protected against
unauthorized access.
• The register descriptions explain the control and status bits associated with the FLASH memory
module.
4.2 HCS08 Core-Defined Memory Map
In the HCS08 architecture, the core defines the address decode for six major blocks within the 64-Kbyte
memory space. The on-chip memory modules use these block decode signals as module selects. The
base address for each peripheral module is determined by additional decode logic in a system integration
module which defines a block of addresses for each peripheral. The peripheral then uses this module
select and additional low-order address lines to develop the select signals for each register within the
module.
4.2.1 HCS08 Memory Map
The five major memory spaces that are defined by the core are shown in Table 4-1. Refer to the data
sheet for a particular derivative for exact information about the size and boundaries of each of these
blocks. 4.2.2 MC9S08GB60 Memory Map shows the memory map for the MC9S08GB60 as a
representative example of an HCS08 MCU memory map.
Table 4-1. Core-Defined Memory Spaces
Name
Direct-page registers
RAM
Address
$0000–$00xx
$00xx–
Comment
Up to 128 bytes
Includes some direct page locations
High-page registers
$1800–$18yy
System configuration
FLASH Memory
–$FFFF
Up to 60 Kbytes
Vectors
$FFC0–$FFFF
Up to 32 x 2 bytes
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
37
On-Chip Memory
Direct-page registers include the I/O port registers and most peripheral control and status registers.
Locating these registers in direct address space ($0000–$00xx) allows bit manipulation instructions to be
used to set, clear, or test any bit in these registers with the BSET, BCLR, BRSET, and BRCLR
instructions. Using the direct addressing mode versions of other instructions to access these registers
also saves program space and execution time compared to the more general extended addressing mode
instructions.
The RAM memory block starts immediately after the end of the direct-page register block and extends to
higher addresses. For example in the MC9S08GB60, the direct-page registers are located at
$0000–$007F and the 4096-byte RAM is located at $0080–$107F. This places a portion of the RAM in
the direct addressing space so that frequently used program variables can take advantage of code size
and execution time savings offered by the direct addressing mode version of many CPU instructions.
Also, since the bit manipulation instruction only support direct addressing mode, this allows
bit-addressable RAM variables.
High-page registers are located at $1800 to $182B. These are registers that are used less often than the
direct-page registers so they are not located in the more valuable direct address space. This space
includes a few system configuration registers such as the COP watchdog and low-voltage detect setup
controls, the debug module registers, and the FLASH module registers.
A few of the registers in the high-page register area should always be located at the same addresses in
all HCS08 derivatives. The SBDFR register at $1801 includes the BDFR control bit which allows a
background debug host to reset the MCU by way of a serial command. There is also a device identification
number in the SDIDH:SDIDL register pair at $1806 and $1807. These registers allow a host debug system
to determine the type of HCS08 and the mask set revision number. This information allows the debug host
to be aware of memory types and sizes, register names, bit names, and addresses in the target MCU.
FLASH memory fills the 64-Kbyte memory map to $FFFF. The starting address of this block depends on
how much FLASH memory is included in the MCU. For example if there is 16 Kbytes of FLASH, it will be
located at $C000–$FFFF. If the FLASH memory block overlaps the high-page register space, the register
block has priority so the FLASH locations at the conflicting addresses are not accessible. This only occurs
when there is more than 57 Kbytes of FLASH.
The vector space is part of the FLASH memory at $FFC0–$FFFF but it is separately decoded so that
other HCS08 modules can recognize when an interrupt vector is being fetched.
Specific HCS08 derivatives have other address areas such as a block of nonvolatile registers and illegal
address blocks. These areas are decoded in a system integration module rather than in the core.
4.2.2 MC9S08GB60 Memory Map
This section describes the memory map of the MC9S08GB60. The data sheet for each HCS08 device
provides similar information explaining the detailed memory map for that HCS08 derivative.
As shown in Figure 4-1, on-chip memory in the MC9S08GB60 consists of RAM, FLASH program memory,
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)
Reset and interrupt vectors are at $FFCC through $FFFF. An illegal address detect feature on some
derivatives forces the MCU to reset if the CPU attempts to access data or execute an instruction from any
address that is identified as an illegal address in the 64-Kbyte memory map.
HCS08 Family Reference Manual, Rev. 2
38
Freescale Semiconductor
HCS08 Core-Defined Memory Map
Background debug mode (BDM) accesses do not trigger an illegal access error. On the MC9S08GB60,
all 64 Kbytes of memory space are used for memory and registers so this device does not have any illegal
address locations.
Unused and reserved locations in register areas are not considered designated illegal addresses and do
not trigger illegal address resets.
$0000
$007F
$0080
DIRECT PAGE REGISTERS
RAM
4096 BYTES
$107F
$1080
FLASH
1920 BYTES
$17FF
$1800
HIGH PAGE REGISTERS
$182B
$182C
FLASH
59348 BYTES
$FFFF
MC9S08GB60
Figure 4-1. MC9S08GB60 Memory Map
4.2.3 Reset and Interrupt Vector Assignments
Table 4-2 shows address assignments for reset and interrupt vectors in the MC9S08GB60. For names
and address assignments for vectors in other HCS08 derivatives, always refer to the appropriate data
sheet. The vector names shown in this table are the labels used in the equate file provided by Freescale
for the MC9S08GB60. For more details about resets, interrupts, interrupt priority, and local interrupt mask
controls, refer to Chapter 5 Resets and Interrupts.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
39
On-Chip Memory
Table 4-2. Reset and Interrupt Vectors for the MC9S08GB60
Address
(High/Low)
Vector
Vector Name
$FFC0:FFC1
Unused Vector Space
(available for user program)
$FFCA:FFCB
$FFCC:FFCD
RTI
Vrti
$FFCE:FFCF
IIC
Viic
$FFD0:FFD1
ATD Conversion
Vatd
$FFD2:FFD3
Keyboard
Vkeyboard
$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
Vspi
$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
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Register Addresses and Bit Assignments
4.3 Register Addresses and Bit Assignments
The registers in the MC9S08GB60 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 the 60-Kbyte FLASH memory at
$FFB0–$FFBF.
Nonvolatile register locations include:
– Two 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
– A reserved location for storage of a trim adjustment value that could be determined during final
testing at Freescale
Since 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 4-3 is a summary of all
user-accessible direct-page registers and control bits.
The registers in Table 4-3 can use the more efficient direct addressing mode so, as a reminder, only the
low order half of the addresses in the first column are shown in bold. In Table 4-4 and Table 4-5 the whole
address in column one is shown in bold. In Table 4-3, Table 4-4, and Table 4-5, 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.
Table 4-3. Direct-Page Register Summary (Sheet 1 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0000
PTAD
PTAD7
PTAD6
PTAD5
PTAD4
PTAD3
PTAD2
PTAD1
PTAD0
$0001
PTAPE
PTAPE7
PTAPE6
PTAPE5
PTAPE4
PTAPE3
PTAPE2
PTAPE1
PTAPE0
$0002
PTASE
PTASE7
PTASE6
PTASE5
PTASE4
PTASE3
PTASE2
PTASE1
PTASE0
$0003
PTADD
PTADD7
PTADD6
PTADD5
PTADD4
PTADD3
PTADD2
PTADD1
PTADD0
$0004
PTBD
PTBD7
PTBD6
PTBD5
PTBD4
PTBD3
PTBD2
PTBD1
PTBD0
$0005
PTBPE
PTBPE7
PTBPE6
PTBPE5
PTBPE4
PTBPE3
PTBPE2
PTBPE1
PTBPE0
$0006
PTBSE
PTBSE7
PTBSE6
PTBSE5
PTBSE4
PTBSE3
PTBSE2
PTBSE1
PTBSE0
$0007
PTBDD
PTBDD7
PTBDD6
PTBDD5
PTBDD4
PTBDD3
PTBDD2
PTBDD1
PTBDD0
$0008
PTCD
PTCD7
PTCD6
PTCD5
PTCD4
PTCD3
PTCD2
PTCD1
PTCD0
$0009
PTCPE
PTCPE7
PTCPE6
PTCPE5
PTCPE4
PTCPE3
PTCPE2
PTCPE1
PTCPE0
$000A
PTCSE
PTCSE7
PTCSE6
PTCSE5
PTCSE4
PTCSE3
PTCSE2
PTCSE1
PTCSE0
$000B
PTCDD
PTCDD7
PTCDD6
PTCDD5
PTCDD4
PTCDD3
PTCDD2
PTCDD1
PTCDD0
$000C
PTDD
PTDD7
PTDD6
PTDD5
PTDD4
PTDD3
PTDD2
PTDD1
PTDD0
$000D
PTDPE
PTDPE7
PTDPE6
PTDPE5
PTDPE4
PTDPE3
PTDPE2
PTDPE1
PTDPE0
$000E
PTDSE
PTDSE7
PTDSE6
PTDSE5
PTDSE4
PTDSE3
PTDSE2
PTDSE1
PTDSE0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
41
On-Chip Memory
Table 4-3. Direct-Page Register Summary (Sheet 2 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$000F
PTDDD
$0010
PTED
PTDDD7
PTDDD6
PTDDD5
PTDDD4
PTDDD3
PTDDD2
PTDDD1
PTDDD0
PTED7
PTED6
PTED5
PTED4
PTED3
PTED2
PTED1
PTED0
$0011
PTEPE
PTEPE7
PTEPE6
PTEPE5
PTEPE4
PTEPE3
PTEPE2
PTEPE1
PTEPE0
$0012
PTESE
PTESE7
PTESE6
PTESE5
PTESE4
PTESE3
PTESE2
PTESE1
PTESE0
$0013
PTEDD
PTEDD7
PTEDD6
PTEDD5
PTEDD4
PTEDD3
PTEDD2
PTEDD1
PTEDD0
$0014
IRQSC
0
0
IRQEDG
IRQPE
IRQF
IRQACK
IRQIE
IRQMOD
$0015
Reserved
—
—
—
—
—
—
—
—
$0016
KBISC
KBEDG7
KBEDG6
KBEDG5
KBEDG4
KBF
KBACK
KBIE
KBIMOD
$0017
KBIPE
KBIPE7
KBIPE6
KBIPE5
KBIPE4
KBIPE3
KBIPE2
KBIPE1
KBIPE0
$0018
SCI1BDH
0
0
0
SBR12
SBR11
SBR10
SBR9
SBR8
$0019
SCI1BDL
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
$001A
SCI1C1
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
$001B
SCI1C2
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
$001C
SCI1S1
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
$001D
SCI1S2
0
0
0
0
0
0
0
RAF
$001E
SCI1C3
R8
T8
TXDIR
0
ORIE
NEIE
FEIE
PEIE
$001F
SCI1D
Bit 7
6
5
4
3
2
1
Bit 0
$0020
SCI2BDH
0
0
0
SBR12
SBR11
SBR10
SBR9
SBR8
$0021
SCI2BDL
SBR7
SBR6
SBR5
SBR4
SBR3
SBR2
SBR1
SBR0
$0022
SCI2C1
LOOPS
SCISWAI
RSRC
M
WAKE
ILT
PE
PT
$0023
SCI2C2
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
$0024
SCI2S1
TDRE
TC
RDRF
IDLE
OR
NF
FE
PF
$0025
SCI2S2
0
0
0
0
0
0
0
RAF
$0026
SCI2C3
R8
T8
TXDIR
0
ORIE
NEIE
FEIE
PEIE
$0027
SCI2D
Bit 7
6
5
4
3
2
1
Bit 0
$0028
SPIC1
SPIE
SPE
SPTIE
MSTR
CPOL
CPHA
SSOE
LSBFE
$0029
SPIC2
0
0
0
MODFEN
BIDIROE
0
SPISWAI
SPC0
$002A
SPIBR
0
SPPR2
SPPR1
SPPR0
0
SPR2
SPR1
SPR0
SPRF
0
SPTEF
MODF
0
0
0
0
0
0
0
0
0
0
0
0
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
$002B
SPIS
$002C
Reserved
$002D
SPID
$002E
Reserved
$002F
Reserved
0
0
0
0
0
0
0
0
$0030
TPM1SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
$0031
TPM1CNTH
Bit 15
14
13
12
11
10
9
Bit 8
$0032
TPM1CNTL
Bit 7
6
5
4
3
2
1
Bit 0
$0033
TPM1MODH
Bit 15
14
13
12
11
10
9
Bit 8
$0034
TPM1MODL
Bit 7
6
5
4
3
2
1
Bit 0
$0035
TPM1C0SC
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
HCS08 Family Reference Manual, Rev. 2
42
Freescale Semiconductor
Register Addresses and Bit Assignments
Table 4-3. Direct-Page Register Summary (Sheet 3 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0036
TPM1C0VH
Bit 15
14
13
12
11
10
9
Bit 8
$0037
TPM1C0VL
Bit 7
6
5
4
3
2
1
Bit 0
$0038
TPM1C1SC
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
$0039
TPM1C1VH
Bit 15
14
13
12
11
10
9
Bit 8
$003A
TPM1C1VL
Bit 7
6
5
4
3
2
1
Bit 0
$003B
TPM1C2SC
CH2F
CH2IE
MS2B
MS2A
ELS2B
ELS2A
0
0
$003C
TPM1C2VH
Bit 15
14
13
12
11
10
9
Bit 8
$003D
TPM1C2VL
Bit 7
6
5
4
3
2
1
Bit 0
$003E–
$003F
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
$0040
PTFD
PTFD7
PTFD6
PTFD5
PTFD4
PTFD3
PTFD2
PTFD1
PTFD0
$0041
PTFPE
PTFPE7
PTFPE6
PTFPE5
PTFPE4
PTFPE3
PTFPE2
PTFPE1
PTFPE0
$0042
PTFSE
PTFSE7
PTFSE6
PTFSE5
PTFSE4
PTFSE3
PTFSE2
PTFSE1
PTFSE0
$0043
PTFDD
PTFDD7
PTFDD6
PTFDD5
PTFDD4
PTFDD3
PTFDD2
PTFDD1
PTFDD0
$0044
PTGD
PTGD7
PTGD6
PTGD5
PTGD4
PTGD3
PTGD2
PTGD1
PTGD0
$0045
PTGPE
PTGPE7
PTGPE6
PTGPE5
PTGPE4
PTGPE3
PTGPE2
PTGPE1
PTGPE0
$0046
PTGSE
PTGSE7
PTGSE6
PTGSE5
PTGSE4
PTGSE3
PTGSE2
PTGSE1
PTGSE0
$0047
PTGDD
PTGDD7
PTGDD6
PTGDD5
PTGDD4
PTGDD3
PTGDD2
PTGDD1
PTGDD0
$0048
ICGC1
0
RANGE
REFS
OSCSTEN
—*
0
CLKS
* This bit is reserved for Freescale internal use only. Always write a 0 to this bit.
$0049
ICGC2
$004A
ICGS1
LOLRE
MFD
$004B
ICGS2
0
$004C
ICGFLTU
0
$004D
ICGFLTL
FLT
$004E
ICGTRM
TRIM
$004F
Reserved
$0050
ATDC
$0051
$0052
CLKST
LOCRE
RFD
REFST
LOLS
LOCK
LOCS
ERCS
ICGIF
0
0
0
0
0
0
DCOS
0
0
0
0
0
FLT
0
0
0
0
0
0
ATDPU
DJM
RES8
SGN
ATDSC
CCF
ATDIE
ATDCO
ATDRH
BIT9
BIT 8
BIT7
BIT6
BIT5
BIT4
BIT3
BIT2
$0053
ATDRL
BIT1
BIT0
0
0
0
0
0
0
$0054
ATDPE
ATDPE7
ATDPE6
ATDPE5
ATDPE4
ATDPE3
ATDPE2
ATDPE1
ATDPE0
$0055–
$0057
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
$0058
IICA
$0059
IICF
PRS
ATDCH
0
ADDR
MULT
ICR
$005A
IICC
IICEN
IICIE
MST
TX
TXAK
RSTA
0
0
$005B
IICS
TCF
IAAS
BUSY
ARBL
0
SRW
IICIF
RXAK
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
43
On-Chip Memory
Table 4-3. Direct-Page Register Summary (Sheet 4 of 4)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$005C
IICD
$005D–
$005F
Reserved
—
—
—
—
—
—
—
—
DATA
—
—
—
—
—
—
—
—
$0060
TPM2SC
TOF
TOIE
CPWMS
CLKSB
CLKSA
PS2
PS1
PS0
$0061
TPM2CNTH
Bit 15
14
13
12
11
10
9
Bit 8
$0062
TPM2CNTL
Bit 7
6
5
4
3
2
1
Bit 0
$0063
TPM2MODH
Bit 15
14
13
12
11
10
9
Bit 8
$0064
TPM2MODL
Bit 7
6
5
4
3
2
1
Bit 0
$0065
TPM2C0SC
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
0
0
$0066
TPM2C0VH
Bit 15
14
13
12
11
10
9
Bit 8
$0067
TPM2C0VL
Bit 7
6
5
4
3
2
1
Bit 0
$0068
TPM2C1SC
CH1F
CH1IE
MS1B
MS1A
ELS1B
ELS1A
0
0
$0069
TPM2C1VH
Bit 15
14
13
12
11
10
9
Bit 8
$006A
TPM2C1VL
Bit 7
6
5
4
3
2
1
Bit 0
$006B
TPM2C2SC
CH2F
CH2IE
MS2B
MS2A
ELS2B
ELS2A
0
0
$006C
TPM2C2VH
Bit 15
14
13
12
11
10
9
Bit 8
$006D
TPM2C2VL
Bit 7
6
5
4
3
2
1
Bit 0
$006E
TPM2C3SC
CH3F
CH3IE
MS3B
MS3A
ELS3B
ELS3A
0
0
$006F
TPM2C3VH
Bit 15
14
13
12
11
10
9
Bit 8
$0070
TPM2C3VL
Bit 7
6
5
4
3
2
1
Bit 0
$0071
TPM2C4SC
CH4F
CH4IE
MS4B
MS4A
ELS4B
ELS4A
0
0
$0072
TPM2C4VH
Bit 15
14
13
12
11
10
9
Bit 8
$0073
TPM2C4VL
Bit 7
6
5
4
3
2
1
Bit 0
$0074–
$007F
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
High-page registers, shown in Table 4-4, 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 4-4. High-Page Register Summary
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$1800
SRS
POR
PIN
COP
ILOP
0
ICG
LVD
0
$1801
SBDFR
0
0
0
0
0
0
0
BDFR
$1802
SOPT
COPE
COPT
STOPE
—
0
0
BKGDPE
—
$1803–
$1805
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
$1806
SDIDH
REV3
REV2
REV1
REV0
ID11
ID10
ID9
ID8
$1807
SDIDL
ID7
ID6
ID5
ID4
ID3
ID2
ID1
ID0
$1808
SRTISC
RTIF
RTIACK
RTICLKS
RTIE
0
RTIS2
RTIS1
RTIS0
$1809
SPMSC1
LVDF
LVDACK
LVDIE
LVDRE
LVDSE
LVDE
0
0
HCS08 Family Reference Manual, Rev. 2
44
Freescale Semiconductor
Register Addresses and Bit Assignments
Table 4-4. High-Page Register Summary (Continued)
Address
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$180A
SPMSC2
LVWF
LVWACK
LVDV
LVWV
PPDF
PPDACK
PDC
PPDC
$180B–
$180F
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
$1810
DBGCAH
Bit 15
14
13
12
11
10
9
Bit 8
$1811
DBGCAL
Bit 7
6
5
4
3
2
1
Bit 0
$1812
DBGCBH
Bit 15
14
13
12
11
10
9
Bit 8
$1813
DBGCBL
Bit 7
6
5
4
3
2
1
Bit 0
$1814
DBGFH
Bit 15
14
13
12
11
10
9
Bit 8
$1815
DBGFL
Bit 7
6
5
4
3
2
1
Bit 0
$1816
DBGC
DBGEN
ARM
TAG
BRKEN
RWA
RWAEN
RWB
RWBEN
$1817
DBGT
TRGSEL
BEGIN
0
0
TRG3
TRG2
TRG1
TRG0
$1818
DBGS
AF
BF
ARMF
0
CNT3
CNT2
CNT1
CNT0
$1819–
$181F
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
$1820
FCDIV
DIVLD
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
$1821
FOPT
KEYEN
FNORED
0
0
0
0
SEC01
SEC00
$1822
Reserved
—
—
—
—
—
—
—
—
$1823
FCNFG
0
0
KEYACC
0
0
0
0
0
$1824
FPROT
FPOPEN
FPDIS
FPS2
FPS1
FPS0
0
0
0
$1825
FSTAT
FCBEF
FCCF
FPVIOL
FACCERR
0
FBLANK
0
0
$1826
FCMD
FCMD7
FCMD6
FCMD5
FCMD4
FCMD3
FCMD2
FCMD1
FCMD0
$1827–
$182B
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
Nonvolatile FLASH registers, shown in Table 4-5, are located in the FLASH memory and include two
nonvolatile setup registers for the FLASH memory module plus an 8-byte backdoor key which optionally
can be used to gain access to secure memory resources. During reset events, the contents of the two
locations in the nonvolatile register area of the FLASH memory are transferred into corresponding
working registers in the high-page registers to control security and block protection options.
Table 4-5. Nonvolatile Register Summary
Address
Register Name
Bit 7
6
5
4
2
1
Bit 0
—
—
—
—
—
—
—
—
FPS1
FPS0
0
0
0
—
—
—
—
—
—
0
0
0
0
SEC01
SEC00
$FFB0–
$FFB7
NVBACKKEY
$FFB8–
$FFBC
Reserved
—
—
—
—
—
—
—
—
$FFBD
NVPROT
FPOPEN
FPDIS
FPS2
—
—
KEYEN
FNORED
(1)
$FFBE
Reserved
$FFBF
NVOPT
3
8-Byte Comparison Key
1. This location can be used to store a trim value for the ICG.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
45
On-Chip Memory
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 (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). See 4.6 Security
(MC9S08GB60) for more details about secure memory.
4.4 RAM
The MC9S08GB60 includes 4096 bytes of static RAM located from $0080 to $107F. The first 128 bytes
of RAM ($0080–$00FF) 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.
Provided the VDD supply voltage remains above the minimum RAM retention voltage and stop1 mode is
not entered, RAM locations retain their contents. If stop1 mode is selected by setting the PDC bit and
clearing the PPDC bit in SPMSC2, when stop1 is entered, the internal voltage regulator is turned off and
voltage is disabled to internal circuitry, including the RAM. Upon exit from stop1, RAM contents are
uninitialized and all other registers return to their reset state. (See Chapter 3 Modes of Operation for more
information about stop modes.)
For compatibility with older M68HC05 MCUs, the HCS08 resets the stack pointer to $00FF. In the
MC9S08GB60, it is usually best to reinitialize the stack pointer to the top of the RAM ($107F) so the direct
page RAM ($0080–$00FF) 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 $107F in the equate file provided by Freescale).
LDHX
TXS
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
4.5 60-Kbyte FLASH
The 60-Kbyte FLASH memory is intended primarily for program storage. In-circuit programming allows
the operating program to be loaded into the FLASH memory after final assembly of the application
product. It is possible to program the entire 60-Kbyte array through the single-wire background debug
interface in about three seconds. Because no special voltages are needed for FLASH erase and
programming operations, in-application programming is also possible through the serial communications
interface (SCI) (RS232 interface) or some other software-controlled communication path. For a more
detailed discussion of in-circuit and in-application programming, refer to 4.8 FLASH Application
Examples.
HCS08 Family Reference Manual, Rev. 2
46
Freescale Semiconductor
60-Kbyte FLASH
4.5.1 Features
Features of the FLASH memory include:
• FLASH — 61268 bytes (120 pages of 512 bytes each)
• Single power supply program and erase
• Command interface for fast program and erase operation
• Fast automated byte program, page or mass erase, and blank check operations (about three
seconds to program 60 Kbytes)
• Up to 100,000 program/erase cycles at typical temperature and voltage
• Flexible block protection
• Security feature for FLASH and RAM
• Auto power-down for low-frequency read accesses
This FLASH memory module includes integrated program/erase voltage generators and separate
command processor state machines which are capable of performing automated byte programming, page
(512 bytes FLASH) or mass erase, and blank check commands. Commands are written to the command
interface, and status flags report errors and indicate when commands are complete.
Blocks of 512, 1K, 2K, 4K, 8K, 16K, or 32K bytes at the end of the FLASH memory can be block protected.
Another control bit allows for block protection of the whole 60-Kbyte FLASH array (see 4.7.4 FLASH
Protection Register (FPROT and NVFPROT). Block protect settings are programmed into a nonvolatile
setup register (NVFPROT). A security mechanism can be engaged to prevent unauthorized access to the
FLASH and RAM memory contents. An optional user-controlled backdoor key mechanism can be used
to allow controlled access to secure memory contents for development purposes.
4.5.2 Program, Erase, and Blank Check Commands
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 4.7.1 FLASH Clock Divider Register (FCDIV)). This register can be written only once, so
normally this write is done during reset initialization. One period of the resulting clock (1/fFCLK) is used by
the command processor to time program and erase pulses. An integer number of these timing pulses are
used by the command processor to complete a program or erase command.
Commands are written to the command interfaces of the FLASH to do any of these:
• Program a byte in the FLASH array
• Erase a 512-byte page of FLASH memory
• Mass erase the whole 60-Kbyte FLASH array
• Check all bytes in the FLASH array for the erased state ($FF)
A strictly monitored procedure must be followed or the command will not be accepted. This minimizes the
possibility of any unintended change to the FLASH memory contents. The command buffer empty flag
(FCBEF) indicates when the command buffer has room to write a new command. The command complete
flag (FCCF) indicates when all commands are complete and no new command is waiting in the associated
FLASH command buffer. A command sequence must be completed by writing a 1 to FCBEF to register
the command before starting any new command for the FLASH memory.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
47
On-Chip Memory
Figure 4-2 demonstrates the procedure for issuing commands. Two types of errors can arise as
commands are issued:
• A protection violation error is indicated by the FPVIOL flag in FSTAT if the command tries to erase
or write to a FLASH location that is block protected (see 4.7.4 FLASH Protection Register (FPROT
and NVFPROT)).
• Any other violation of the required sequence or other error condition will set the access error
(FACCERR) flag bit in the FSTAT register. Refer to 4.5.4 Access Errors for a detailed list of actions
that cause access errors.
START
FACCERR ?
0
1
CLEAR ERROR
FCBEF ?
0
1
WRITE TO FLASH
TO BUFFER ADDRESS AND DATA
WRITE COMMAND TO FCMD
WRITE 1 TO FCBEF
TO REGISTER COMMAND
AND CLEAR FCBEF(1)
FPVIOL OR
FACCERR ?
(1)
Wait at least four bus cycles before
checking FCBEF or FCCF.
YES
ERROR EXIT
NO
YES
MORE COMMANDS ?
NO
0
FCCF ?
1
DONE
Figure 4-2. FLASH Command Flowchart
HCS08 Family Reference Manual, Rev. 2
48
Freescale Semiconductor
60-Kbyte FLASH
Assuming no protection violation or access errors arise, a command sequence can be simplified to three
basic steps. They 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 command buffer and 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 60-Kbyte
FLASH memory.
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 register 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 registers the complete command.
Aborting a command in this way sets the FACCERR access error flag which must be cleared before
starting a new command.
4.5.3 Command Timing and Burst Programming
This section explains the sequence and timing of nonvolatile memory commands in greater detail. When
more than one byte within a row is programmed one after the other, it is called burst programming. Byte
programming takes slightly longer for the first byte in a row compared to queued byte programming
commands for subsequent bytes within the same row.
4.5.3.1 Rows and FLASH Organization
The 60-Kbyte FLASH memory array is made up of 120 pages of 512 bytes each. Each page is made up
of 8 rows of 64 bytes each, beginning at address $1000. Address lines A5–A0 define an address within
a FLASH row, A8–A6 identify the row number, and A15–A9 identify the page number. Whole pages of
512 bytes are the smallest block of FLASH that may be erased. The first 128 bytes ($1000–$107F) of the
first FLASH row are hidden behind the higher priority RAM located at these same locations.
Rows are important because a burst program command takes less time when the address is within the
same row as the previous byte or burst program command. To benefit from this reduced program time,
the burst programming command must be registered in the command buffer before the previous byte
programming operation in the same row is completed (otherwise, the small extra overhead for a new byte
programming operation applies).
4.5.3.2 Program Command Timing Sequence
For this discussion, we assume the FCDIV setting results in a 5-μs timing pulse to the command state
machine. If the FCDIV setting and system clock speed result in a different timing pulse period, all
programming time intervals will need to be adjusted accordingly.
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On-Chip Memory
A complete program command consists of seven timing intervals. They are:
• Start — 0 to 5 μs, depending on synchronization between the command and the 200-kHz internal
nonvolatile memory clock. When the command buffer is kept full, each command ends at an edge
of the 200-kHz clock. The new command needs to wait a full period to synchronize to the clock so
the start time can normally be taken to be the full 5 μs.
• Nonvolatile setup — 5 μs
• Program setup — 10 μs
• Program byte — 20 μs
• Program hold — 10 ns (negligible)
• Nonvolatile hold — 5 μs (minus the program hold time)
• Memory recover time — 5 μs
Programming more than one location in the same row (and as long as the command buffer remains filled
with a burst program command so there is no gap between commands) is called burst programming, and
all steps except the byte programming time are skipped.
Table 4-6 shows program and erase times. System clock and control bit settings determine the frequency
of FCLK (fFCLK). The time for one cycle of FCLK is tFcyc = 1/fFCLK. The times are shown as a number of
cycles of FCLK and as an absolute time for the case where tFcyc = 5 μs.
Table 4-6. Program and Erase Times
Parameter
Cycles of FCLK
Time if FCLK = 200 kHz
Byte program
9
45 μs
Byte program (burst)
4
20 μs(1)
Page erase
4000
20 ms
Mass erase
40,000
200 ms
1. Excluding start/end overhead
4.5.4 Access Errors
Any of the following specific actions will cause the access error flag (FACCERR) in FSTAT to be set. In
the case of an access error, FACCERR must be cleared by writing a 1 to FACCERR in FSTAT before
starting a new command.
• Writing to a FLASH address before the internal FLASH clock frequency has been set by writing to
the FCDIV register
• Writing to an unimplemented FLASH location before writing to FCMD (MC9S08GB60 has no
unimplemented FLASH locations.)
• 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 registering the previous command (There is only
one write to FLASH for every command.)
• Writing a second time to FCMD before registering 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
• Writing to any FLASH control register other than FSTAT (to clear FCBEF and register the
command) after writing the command to FCMD
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Security (MC9S08GB60)
•
•
•
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
4.5.5 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.
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.
4.5.6 FLASH Block Protection (MC9S08GB60)
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 MC9S08GB60 allows
a block of memory at the end of FLASH and/or the entire 60 Kbytes of FLASH memory to be block
protected. A disable control bit and a 3-bit control field allow you to set the size of this block to 512, 1K,
2K, 4K, 8K, 16K, or 32K bytes. A separate control bit allows block protection of the whole 60-Kbyte FLASH
memory array. All five of these control bits are located in the FPROT register (see 4.7.4 FLASH Protection
Register (FPROT and NVFPROT)).
At reset, the high-page register (FPROT) is loaded with the contents of the NVFPROT 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 NVFPROT 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. Then
this bootloader program can be used to erase the rest of the FLASH memory and reprogram it. Since the
bootloader is protected, it remains intact even if MCU power is lost in the middle of an erase and
reprogram operation.
4.6 Security (MC9S08GB60)
The MC9S08GB60 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.
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51
On-Chip Memory
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 NVFOPT are copied from FLASH
into the working FOPT register in high-page register space. A user engages security by programming the
NVFOPT 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 that 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 NVFOPT 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 non-intrusive 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 NVFOPT/FOPT is 0, the backdoor key is disabled and there
is no way to disengage security without completely erasing all FLASH locations. If KEYEN is 1, a secure
user program can temporarily disengage security by:
1. Writing 1 to KEYACC in the FCNFG register. This makes the FLASH module interpret writes to the
backdoor comparison key locations (NVBACKKEY through NVBACKKEY+7) as values to be
compared against the key rather than as the first step in a FLASH program or erase command.
2. Writing the user-entered key values to the NVBACKKEY through NVBACKKEY+7 locations. These
writes must be done in order starting with the value for NVBACKKEY and ending with
NVBACKKEY+7. Normally, user software would get the key codes from outside the MCU system
through a communication interface such as the SCI.
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 a secure memory, so it cannot be entered through background
commands without the cooperation of a secure user program.
The backdoor comparison key (NVBACKKEY through NVBACKKEY+7) is located in FLASH memory
locations in the nonvolatile register space so users can program these locations 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 following 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.
4. To avoid returning to secure mode after the next reset, program NVFOPT so SEC01:SEC00 = 1:0.
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FLASH Registers and Control Bits (MC9S08GB60)
4.7 FLASH Registers and Control Bits (MC9S08GB60)
Although these registers and bits are representative of the FLASH registers and control bits in any HCS08
derivative, always refer to the data sheet for a specific HCS08 derivative when writing application
software. The FLASH module in the MC9S08GB60 has six 8-bit registers in the high-page register space,
two locations in the nonvolatile register space in FLASH memory which are copied into two corresponding
high-page control registers at reset. There is also an 8-byte comparison key in FLASH memory. Refer to
Table 4-4 and Table 4-5 for the absolute address assignments for all FLASH registers. This section refers
to registers and control bits only by their names. Normally, an equate or header file provided by Freescale
is used to translate these names into the appropriate absolute addresses.
4.7.1 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:
DIVLD
Write:
Reset:
0
6
5
4
3
2
1
Bit 0
PRDIV8
DIV5
DIV4
DIV3
DIV2
DIV1
DIV0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-3. 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 operation. 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.
Equation 1:
if PRDIV8 = 0, then fFCLK = fBus ÷ ([DIV5:DIV0] + 1)
Equation 2:
if PRDIV8 = 1, then fFCLK = fBus ÷ (8 × ([DIV5:DIV0] + 1))
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On-Chip Memory
Table 4-7 shows the appropriate values for PRDIV8 and [DIV5:DIV0] for selected bus frequencies.
Table 4-7. FLASH Clock Divider Settings
fBus
PRDIV8
(Binary)
[DIV5:DIV0]
(Decimal)
fFCLK
Program/Erase Timing Pulse
(5 μs Min, 6.7 μs Max)
20 MHz
1
12
192.3 kHz
5.2 μs
10 MHz
0
49
200 kHz
5 μs
8 MHz
0
39
200 kHz
5 μs
4 MHz
0
19
200 kHz
5 μs
2 MHz
0
9
200 kHz
5 μs
1 MHz
0
4
200 kHz
5 μs
200 kHz
0
0
200 kHz
5 μs
150 kHz
0
0
150 kHz
6.7 μs
4.7.2 FLASH Options Register (FOPT and NVFOPT)
During reset, the contents of the nonvolatile location NVOPT are copied from FLASH into FOPT. Bits 6
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 4-4. 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 4.6 Security (MC9S08GB60).
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, then vector redirection is disabled.
1 = Vector redirection disabled.
0 = Vector redirection enabled.
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FLASH Registers and Control Bits (MC9S08GB60)
SEC01:SEC00 — Security State Code
This 2-bit field determines the security state of the MCU as shown in Table 4-8. 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 4.6 Security (MC9S08GB60).
Table 4-8. 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 the
FLASH memory.
4.7.3 FLASH Configuration Register (FCNFG)
Bit 5 may be read or written at any time. The remaining bits always read 0 and cannot be written.
Read:
Bit 7
6
0
0
Write:
Reset:
0
0
5
KEYACC
0
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-5. 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 4.6 Security (MC9S08GB60).
1 = Writes to NVBACKKEY ($FFB0–$FFB7) are interpreted as comparison key writes.
0 = Writes to $FFB–$FFB7 are interpreted as the start of a FLASH programming or erase
command.
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On-Chip Memory
4.7.4 FLASH Protection Register (FPROT and NVFPROT)
During reset, the contents of the nonvolatile location NVFPROT is copied from FLASH into FPROT. Bit 6
is not used and always reads 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 at $1824.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
FPOPEN
FDIS
FPS2
FPS1
FPS0
0
0
0
Write:
(1)
(1)
(1)
(1)
(1)
Reset:
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 4-6. 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 = Whole FLASH is block protected (no program or erase allowed).
FPDIS — FLASH Protection Disable
1 = No FLASH block is protected.
0 = FLASH block specified by FPS2:FPS1:FPS0 is block protected (program and erase not
allowed).
FPS2:FPS1:FPS0 — FLASH Protect 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 4-9). Protected FLASH locations cannot be erased or
programmed.
Table 4-9. High Address Protected Block
FPS2:FPS1:FPS0
Protected Address Range
Protected Block Size
Redirected Vectors(1)
0:0:0
$FE00–$FFFF
512 bytes
$FDC0–$FDFD(2)
0:0:1
$FC00–$FFFF
1 Kbytes
$FBC0–$FBFD
0:1:0
$F800–$FFFF
2 Kbytes
$F7C0–$F7FD
0:1:1
$F000–$FFFF
4 Kbytes
$EFC0–$EFFD
1:0:0
$E000–$FFFF
8 Kbytes
$DFC0–$DFFD
1:0:1
$C000–$FFFF
16 Kbytes
$BFC0–$BFFD
1:1:0
$8000–$FFFF
32 Kbytes
$7FC0–$7FFD
1:1:1
$8000–$FFFF
32 Kbytes
$7FC0–$7FFD
1. No redirection if FPOPEN = 0, or FNORED = 1.
2. Reset vector is not redirected.
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FLASH Registers and Control Bits (MC9S08GB60)
4.7.5 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
Read:
Write:
FCBEF
Reset:
1
6
FCCF
1
5
4
FPVIOL
FACCERR
0
0
3
2
1
Bit 0
0
FBLANK
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-7. FLASH Status Register (FSTAT)
FCBEF — FLASH Command Buffer Empty Flag
FLASH commands are buffered so a second command can be written into the buffer while the
command processor is executing another command during a burst programming sequence. As soon
as a command is finished, the command processor can start on an additional burst programming
command if one is present in the buffer.
FCBEF is set automatically when the command buffer can accept a new command. A command is
registered, and FCBEF is cleared, by writing a 1 to the FCBEF bit. Writing 0 to FCBEF, after a write to
the FLASH but before the FCBEF clear that registers the command, causes the partially entered
command to be manually aborted and clears the command buffer.
1 = A new 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
automatically 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 4.5.4 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
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On-Chip Memory
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.
4.7.6 FLASH Command Register (FCMD)
Bits 7, 4, 3, and 1 always read 0 and cannot be written by user application programs. Only five command
codes are recognized in normal user modes as shown in Table 4-10. Refer to 4.5.2 Program, Erase, and
Blank Check Commands for a detailed discussion of FLASH programming and erase operations.
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
FCMP7
FCMP6
FCMP5
FCMP4
FCMP3
FCMP2
FCMP1
FCMP0
0
0
0
0
0
0
0
0
Figure 4-8. FLASH Command Register (FCMD)
Table 4-10. 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. Blank check is
required only as part of the security unlocking mechanism.
4.8 FLASH Application Examples
This section discusses several examples to demonstrate how programming and erase operations are
performed on the FLASH in an HCS08 MCU. These examples focus on the routines that would be found
in typical application systems as opposed to the programs that are used to program the initial application
programs into the FLASH the first time. Normally, a third-party development tool would be used to
program the first application programs (including programs such as those shown in these examples) into
the HCS08 system.
A complete monitor program is presented and discussed in application note AN2140, Serial Monitor for
MC9S08GB60. This bootloader resides in protected FLASH at the high-address end of the FLASH and
works through the asynchronous serial communications interface (SCI1) of the MC9S08GB60 to allow a
user to program or erase FLASH, or debug user applications.
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FLASH Application Examples
A set of primitive binary monitor commands is supported by this monitor so a host debugger running on
your PC can read and write memory or registers, set breakpoints, trace instructions, or go to a user
program. Refer to AN2140 for more information.
Most third-party debug systems and programmers use the background debug interface for all
programming operations. Typically, they would download a small routine into the RAM of the target
system and then jump to that routine. This is more efficient than manipulating the FLASH programming
controls through serial background debug commands so it is the preferred method when larger blocks of
nonvolatile memory need to be programmed. Since the nonvolatile memory modules in HCS08 devices
have built-in state machines to process critical timing operations, it is possible to manipulate the
programming controls directly through serial background commands. Normally, this would only be done
if the development host needed to program a few individual locations.
4.8.1 Initialization of the FLASH Module Clock
The internal state machines that control programming and erase operations on the FLASH use a 150 kHz
to 200 kHz clock (FCLK) which is derived by dividing the BUSCLK. The FLASH clock divider register
(FCDIV) is used to set the divider. FCDIV can only be written one time after reset and no programming
or erase operations are allowed until this register has been written. It is customary to write this register
during a reset initialization routine shortly after reset.
The divider must be set so that FCLK is between 150 kHz and 200 kHz. Programming and erase
operations use a fixed number of these clock cycles so the closer FCLK is to 200 kHz, the faster
commands can be performed. For example if FCLK is 200 kHz, it takes 45 microseconds to program a
single random location in FLASH. If FCLK is 150 kHz, the same byte program operation takes
60 microseconds.
Refer to Figure 4-9 for the following discussion. The first part of this code example shows an application
equate which sets up the initialization value for the FCDIV register. The second part shows the two lines
of code that would be placed in the reset initialization routine. Notice that we could not use a MOV
instruction to set the initial value in FCDIV because it is a high-page register and MOV can only be used
for immediate, direct, or indexed operands. The initialization value shown in this example is for a system
that has a 32.768 kHz crystal and is using the FLL to multiply this up to BUSCLK = 18.874368 MHz. The
value in FCDIV causes this to be divided by 8 × 12, producing FCLK = 196.608 kHz (as close to 200 kHz
as possible without going over).
initFCDIV:
;
;
;
;
;
;
;
;
;
equ
lda
sta
%01001011
;FLASH clock divider
||||||||
|||||||+-DIV0 \
||||||+--DIV1 |
|||||+---DIV2 >-- divide by (11+1)
||||+----DIV3 |
BUSCLK/(8*12)~=196,608 Hz
|||+-----DIV4 |
||+------DIV5 /
|+-------PRDIV8 -- divide (prescale) by 8
+--------DIVLD --- read-only status
initFCDIV
FCDIV
;set fFCLK = about 200kHz
Figure 4-9. FCLK Initialization
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The requirement for FCLK to be at least 150 kHz implies that BUSCLK must also be at least 150 kHz
(because the smallest divide that can be set by FCDIV is 1). This requirement only applies to
programming and erase operations, not to reads. This means lower bus frequencies may be used to
reduce power consumption, but the bus frequency must be at least 150 kHz during program and erase
operations.
Applications that adjust the bus frequency during normal operations (using post-FLL divider controls),
must be aware of the FCLK frequency requirements for programing and erase operations. Since the
FCDIV register is write-once, it cannot be adjusted to accommodate dynamic changes in bus frequency.
During program and erase operations, the bus clock would need to be changed to make FCLK fall within
legal limits. Many applications do not adjust the bus clock frequency dynamically so this issue does not
arise.
4.8.2 Erase One 512-Byte Page in FLASH
Program and erase operations for the FLASH memory are a little more complicated compared to many
application programs because it is not possible to execute a program out of FLASH during FLASH
program and erase operations. This example shows one way to overcome this limitation by placing the
routine on the stack so the CPU is executing out of stack RAM while the FLASH is unavailable due to the
program or erase operation.
The example shown in Figure 4-10 is located in the FLASH memory and can be used to erase one
512-byte page of FLASH (that is, any page other than the page where this routine is located). This routine
is useful because HCS08 devices have no separate EEPROM. In an HCS08 device, one or more pages
of FLASH could be used for storage of nonvolatile configuration values or logged history data. Typically,
the main body of the application code, including these routines, would reside in a block protected portion
of the FLASH. A BDM interface pod is required to change the block protection settings so protected code
cannot be erased accidentally or altered as a result of an application program error.
;*********************************************************************
;* FlashErase1 - erases one page of FLASH (512 bytes)
;*
;* On entry... H:X - points at a location in the page to be erased
;*
;* Calling convention:
;*
jsr
FlashErase1
;*
;* Uses: DoOnStack which uses SpSub
;* Returns: H:X unchanged and A = FSTAT shifted left by 2 bits
;* Z=1 if OK, Z=0 if protect violation or access error
;* uses 32 bytes of stack space + 2 bytes for BSR/JSR used to call it
;*********************************************************************
FlashErase1: psha
;adjust sp for DoOnStack entry
lda
#(mFPVIOL+mFACCERR) ;mask
sta
FSTAT
;abort any command and clear errors
lda
#mPageErase
;mask pattern for page erase command
bsr
DoOnStack
;finish command from stack-based sub
ais
#1
;deallocate data location from stack
rts
;Z = 0 means there was an error
;********************
Figure 4-10. Erase One 512-Byte Page in FLASH
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FLASH Application Examples
This FlashErase1 routine calls the DoOnStack subroutine which, in turn, copies a small instruction
sequence onto the stack and jumps to that stack routine to complete the requested FLASH program or
erase command before returning to the calling program in FLASH. The initial steps in the FLASH program
or erase command can be executed from within the FLASH, but the command sequence itself should not
be executed from within the FLASH memory.
The PDHA instruction at the beginning of FlashErase1 places a dummy data value onto the stack so the
DoOnStack subroutine can fetch it with an LDA SpSubSize+6,sp instruction later. The AIS #1 instruction
just before the RTS instruction at the end of FlashErase1 deallocates this byte before returning.
Just in case there was a pending protection violation or access error (FPVIOL or FACCERR) from some
previous operation, the second and third instructions in FlashErase1 will clear these flags so the
command processor is ready to receive a new command. Within this example case we do not check these
error flags because we are assuming we know what we are doing. However, some applications will
include additional checks of FPVIOL and FACCERR to guard against unintended errors such as an
attempt to erase a protected location.
4.8.3 DoOnStack Subroutine
This is an unusual subroutine (see Figure 4-11) because it moves instructions onto the stack and then
jumps there so that the FLASH command subroutine finishes execution from the stack RAM. This solves
the problem that you cannot execute instructions out of the FLASH memory while any program or erase
operation is in progress. The DoOnStack subroutine is located in FLASH, but during the critical portion of
the routine when the program or erase command is actually in progress, the CPU will be executing
instructions on the stack (that is, in the on-chip RAM).
First, DoOnStack pushes the FLASH location pointer (H:X) and the command code (A) onto the stack to
free up these CPU registers. H:X is set to point at the last byte of the SpSub subroutine. Next, a
5-instruction loop copies the stack routine from FLASH onto the stack one byte at a time. After moving
the last byte onto the stack, SP points at the next lower address. The TSX instruction adds one to SP as
the value is copied to the H:X register pair. This leaves H:X pointing at the first byte of the routine that was
just moved onto the stack.
The next several instructions are used to determine whether or not interrupts are masked. If interrupts are
masked (I set to 1), A is loaded with the data for the FLASH program or erase operation and the copy of
SpSub on the stack is called. If interrupts were not masked, an SEI instruction is used to block interrupts,
A is loaded, SpSub is called (JSR ,X), and the ACLI re-enables interrupts. The stack subroutine is
described in 4.8.4 SpSub Subroutine immediately below.
After returning from SpSub, the AIS #SpSubSize+3 instruction deallocates the stack space used for
SpSub and associated parameters. ASLA moves the PVIOL and ACCERR error flags to the most
significant 2 bits of A. A should now be 0 if there were no errors.
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;*********************************************************************
;* DoOnStack - copy SpSub onto stack and call it (see also SpSub)
;* Deallocates the stack space used by SpSub after returning from it.
;* Allows flash prog/erase command to execute out of RAM (on stack)
;* while flash is out of the memory map.
;* This routine can be used for flash byte-program or erase commands
;*
;* Calling Convention:
;*
psha
;save data to program (or dummy
;*
; data for an erase command)
;*
lda
#(mFPVIOL+mFACCERR) ;mask
;*
sta
FSTAT
;abort any command and clear errors
;*
lda
#mByteProg
;mask pattern for byte prog command
;*
jsr
DoOnStack
;execute prog code from stack RAM
;*
ais
#1
;deallocate data location from stack
;*
; without disturbing A or CCR
;*
;*
or substitute #mPageErase for page erase
;*
;* Uses 29 bytes on stack + 2 bytes for BSR/JSR used to call it
;* returns H:X unchanged and A=0 and Z=1 if no flash errors
;********************************************************************
DoOnStack:
pshx
pshh
;save pointer to flash
psha
;save command on stack
ldhx
#SpSubEnd
;point at last byte to move to stack
SpMoveLoop: lda
,x
;read from flash
psha
;move onto stack
aix
#-1
;next byte to move
cphx
#SpSub-1
;past end?
bne
SpMoveLoop
;loop till whole sub on stack
tsx
;point to sub on stack
tpa
;move CCR to A for testing
and
#$08
;check the I mask
bne
I_set
;skip if I already set
sei
;block interrupts while FLASH busy
lda
SpSubSize+6,sp ;preload data for command
jsr
,x
;execute the sub on the stack
cli
;ok to clear I mask now
bra
I_cont
;continue to stack de-allocation
I_set:
lda
SpSubSize+6,sp ;preload data for command
jsr
,x
;execute the sub on the stack
I_cont:
ais
#SpSubSize+3 ;deallocate sub body + H:X + command
;H:X flash pointer OK from SpSub
lsla
;A=00 & Z=1 unless PVIOL or ACCERR
rts
;to flash where DoOnStack was called
;********************
Figure 4-11. DoOnStack Subroutine (Complete FLASH Command)
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FLASH Application Examples
4.8.4 SpSub Subroutine
The SpSub subroutine (see Figure 4-12) is moved onto the stack by the DoOnStack subroutine
(described in 4.8.3 DoOnStack Subroutine immediately above) and then it is called (from DoOnStack).
This subroutine completes the program or erase command and then waits for all FLASH commands to
finish before returning. These instructions are located on the stack in on-chip RAM when they are
executed. This satisfies the requirement that you cannot execute instructions out of FLASH while a
program or erase command is in progress.
;*********************************************************************
;* SpSub - This variation of SpSub performs all of the steps for
;* programming or erasing flash from RAM. SpSub is copied onto the
;* stack, SP is copied to H:X, and then the copy of SpSub in RAM is
;* called using a JSR 0,X instruction.
;*
;* At the time SpSub is called, the data to be programmed (dummy data
;* for an erase command), is in A and the flash address is on the
;* stack above SpSub. After return, PVIOL and ACCERR flags are in bits
;* 6 and 5 of A. If A is shifted left by one bit after return, it
;* should be zero unless there was a flash error.
;*
;* Uses 24 bytes on stack + 2 bytes if a BSR/JSR calls it
;*********************************************************************
SpSub:
ldhx
SpSubSize+4,sp ;get flash address from stack
sta
0,x
;write to flash; latch addr and data
lda
SpSubSize+3,sp ;get flash command
sta
FCMD
;write the flash command
lda
#mFCBEF
;mask to initiate command
sta
FSTAT
;[pwpp] register command
nop
;[p] want min 4~ from w cycle to r
ChkDone:
lda
FSTAT
;[prpp] so FCCF is valid
lsla
;FCCF now in MSB
bpl
ChkDone
;loop if FCCF = 0
SpSubEnd:
rts
;back into DoOnStack in flash
SpSubSize:
equ
(*-SpSub)
;********************
Figure 4-12. SpSub Subroutine (Executes on Stack)
In SpSub, H:X is loaded (using a stack pointer-relative LDHX instruction) with the address for the FLASH
program or erase operation. The STA o,x instruction completes the first step of the FLASH program or
erase command sequence. Next, another stack pointer-relative LOAD instruction is used to load A with
the command code for a PageErase or a ByteProgram command and this code is written to FCMD. The
next two instruction write a 1 to the FCBEF bit in FSTAT to register the command and start the program
or erase operation.
The cycle-by-cycle activity for the STA FSTAT, NOP, and LDA FSTAT instructions is shown in square
brackets in the comment fields of these instructions because there is a requirement that there must be at
least four cycles after the FSTAT write that registers the command before the first read to check the
FCBEF or FCCF status flags. The p cycles are program fetch cycles, the w cycle is where the FSTAT
register was written, and the r cycle is where the FSTAT register is read.
Next, the ASLA instruction moves the FCCF flag to the MSB of the accumulator and sets or clears the N
bit in the CCR according to the value of FCCF (now in this MSB). If FCCF was clear, the BPL instruction
will cause a branch back to ChkDoneE1 to repeat the status check. When FCCF is set, the branch will fall
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On-Chip Memory
through indicating the command is finished and no additional commands are pending. At this point, the
FLASH reappears in the memory map so it is safe to use the RTS instruction to return to the calling
program in FLASH.
4.8.5 Program One Byte of FLASH
This example demonstrates a simple routine to program a single location in FLASH. It assumes the
location was previously blank (erased to $FF) and does not perform any error checking. We assume we
are following the correct programming procedure so we will not get access errors and we assume the
programmer knows that the location is not located in a protected block which would cause a protection
violation error. This example uses the DoOnStack and SpSub routines described in 4.8.3 DoOnStack
Subroutine and 4.8.4 SpSub Subroutine above.
;*********************************************************************
;* FlashProg1 - programs one byte of FLASH
;* This routine waits for the command to complete before returning.
;* assumes location was blank. This routine can be run from FLASH
;*
;* On entry... H:X - points at the FLASH byte to be programmed
;*
A holds the data for the location to be programmed
;*
;* Calling convention:
;*
jsr
FlashProg1
;*
;* Uses: DoOnStack which uses SpSub
;* Returns: H:X unchanged and A = FSTAT shifted left by 2 bits
;* Z=1 if OK, Z=0 if protect violation or access error
;* uses 32 bytes of stack space + 2 bytes for BSR/JSR used to call it
;*********************************************************************
FlashProg1: psha
;temporarily save entry data
lda
#(mFPVIOL+mFACCERR) ;mask
sta
FSTAT
;abort any command and clear errors
lda
#mByteProg
;mask pattern for byte prog command
bsr
DoOnStack
;execute prog code from stack RAM
ais
#1
;deallocate data location from stack
rts
;Z = 0 means there was an error
;********************
Figure 4-13. Program One Byte in FLASH
One advantage of the way FlashProg1 and FlashErase1 are written is that this code can reside in FLASH.
Only the code for the actual programming or erase operation is copied onto the stack so it can be
executed in RAM while the FLASH is out of the memory map.
One drawback to this approach is that each command must be completed before anything else can be
done. For applications where only a few locations are programmed at a time, this limitation is not serious.
On the other hand, this approach would not be appropriate for programming larger blocks of data into the
FLASH. For those cases use an approach where the entire programming algorithm is located in a RAM
routine. Burst programming commands can be queued such that there is always another command
waiting in a buffer so it can immediately transfer into the on-chip command processor as soon as the
previous command finishes. In the case of programming multiple bytes within the same 64-byte FLASH
row, this allows burst programming which takes less than half as long as programming a single isolated
byte.
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Chapter 5
Resets and Interrupts
5.1 Introduction
This section discusses the basic reset and interrupt mechanisms along with the various sources of reset
and interrupts in most HCS08 derivatives. Some interrupt sources from peripheral modules are discussed
in greater detail within other sections of this reference manual. This section gathers 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 periodic interrupt timer, are not part of on-chip
peripheral systems that have their own sections. These functions and their registers are described in this
section. For more information about the reset and interrupt sources for a specific derivative, refer to the
appropriate data sheet.
5.2 Reset and Interrupt Features for MC9S08GB60
The set of reset and interrupt sources differs for each HCS08 derivative. This section describes the
sources for the first HCS08 device (MC9S08GB60). Refer to the data sheet for a specific device for more
information.
Reset and interrupt sources include:
• Eight possible sources of reset:
– Power-on detection (POR)
– External RESET pin with enable
– COP watchdog with enable and two timeout choices
– Illegal address (not applicable on the MC9S08GB60)
– Illegal opcode detect
– Clock generator loss-of-lock and loss-of-clocks
– Low-voltage detect (LVD) with enable
– Serial command from a background debug host
• Reset status register to indicate cause of most recent reset
• 25 separate interrupt vectors (reduces polling overhead):
– Software interrupt instruction (SWI)
– IRQ pin with enable, choice of polarity, level, and/or edge
– Low-voltage detect with enable
– Clock generator loss-of-lock or loss-of-clocks
– Ten timer interrupts; two overflow, eight channels total for two TPMs
– One SPI interrupt
– Six SCI interrupts; Rx, Tx, and error for each of two SCIs
– Keyboard wakeup
– ATD conversion complete
– Periodic wakeup from stop with enable and multiple rates based on a separate 1-kHz
self-clocked source or an external source
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Resets and Interrupts
5.3 MCU Reset
Reset 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 until the user program has a chance to initialize the
stack pointer (SP) and system control settings. SP is forced to $00FF at reset, but this is almost never
where the stack should be located in an HCS08 system. Normally, SP should be changed during reset
initialization.
The MCU defaults to using the self-clocked mode (approximately 4 MHz bus clock) so it doesn’t need to
wait for the external oscillator to start and stabilize. In most systems, the user’s initialization program will
configure the clock module to operate at the system’s optimal frequency.
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 and controlled by the SOPT register (see 5.8.4 System Options Register (SOPT) for
additional information). The COP timer is reset by writing any value to the address of the reset status
register (SRS). This write does not affect the data in the read-only SRS register. 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, because depending on any application program instructions to
enable the watchdog that is supposed to detect software errors is not reliable. 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, you should still write to the
write-once SOPT register during reset initialization to lock in the settings so 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.
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 that processing resumes where it left off before the interrupt.
Other than software interrupt (SWI), which is a program instruction, interrupts are caused by hardware
events such as an edge on the IRQ pin or the reception of a serial I/O character. The debug module can
also generate SWI interrupts under certain circumstances (see 7.5.9 Hardware Breakpoints and ROM
Patching).
If an event occurs in an enabled interrupt source, an associated read-only status flag will become set, but
the CPU will not respond until and unless the local interrupt mask is a logic 1 to enable the interrupt and
the I bit in the condition code register (CCR) is logic 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. This allows
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Interrupts
the user program to initialize the stack pointer and perform other system setup before clearing the I bit to
allow the CPU to respond to interrupts.
When the CPU receives a qualified interrupt request, it completes the current instruction before
responding to the interrupt. The interrupt sequence 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 that was 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. For compatibility with the M68HC08, the H register is not automatically saved and restored. So 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.
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 condition
code register (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.
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 that was just recovered from the stack.
The status flag that caused the interrupt must be acknowledged (cleared) before returning from the ISR.
Typically, the flag should be cleared at the beginning of the ISR so that if another interrupt is generated
by this same source, it will be registered so it can be serviced after completion of the current ISR.
5.5.2 External Interrupt Request (IRQ) Pin
External interrupts are managed by the IRQ status and control register (IRQSC). When the IRQ function
is enabled, synchronous logic monitors the pin for edge-only or edge-and-level events. When the MCU is
in stop mode and system clocks are shut down, an asynchronous path is used so the IRQ (if enabled) can
wake the MCU from stop.
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TOWARD LOWER ADDRESSES
•
UNSTACKING
ORDER
•
•
7
0
SP AFTER
INTERRUPT STACKING
5
1
CONDITION CODE REGISTER
4
2
ACCUMULATOR
3
3
2
4
PROGRAM COUNTER HIGH
1
5
PROGRAM COUNTER LOW
INDEX REGISTER (LOW BYTE X)
*
SP BEFORE
THE INTERRUPT
•
•
STACKING
ORDER
•
TOWARD HIGHER ADDRESSES
* High byte (H) of index register is not stacked.
Figure 5-1. Interrupt Stack Frame
5.5.2.1 Pin Configuration Options
The IRQ pin enable (IRQPE) control bit in the IRQSC register must be 1 in order for the IRQ pin to act as
the interrupt request (IRQ) input. As an IRQ input, the user can choose the polarity of edges or levels
detected (IRQEDG), whether the pin detects edges-only or edges and levels (IRQMOD), and whether an
event causes an interrupt or just 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.
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
Synchronous logic is used to detect edges. Prior to detecting an edge, the IRQ pin must be at its
deasserted logic level. A falling edge is detected when the enabled IRQ input signal is seen at logic 1
during one bus cycle and then at logic 0 during the next cycle. A rising edge is detected when the input
signal is seen as a logic 0 during one bus cycle and then a logic 1 during the next cycle.
The IRQMOD control bit can be set to reconfigure the detection logic so that it detects edges and levels.
In this 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.
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Low-Voltage Detect (LVD) System
5.5.3 Interrupt Vectors, Sources, and Local Masks
Table 5-1 provides a summary of all interrupt sources in the MC9S08GB60. 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. The vector name is the label used in the
equate or header file provided by Freescale.
When an interrupt condition occurs, an associated flag bit becomes set. If the associated local interrupt
mask 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.
5.6 Low-Voltage Detect (LVD) System
The 9S08GB/GT includes a system to protect against low voltage conditions in order to protect memory
contents and control MCU system states during supply voltage variations. The system is comprised of a
power-on reset (POR) circuit and an LVD circuit with a user selectable trip voltage, either high (VLVDH) or
low (VLVDL). The LVD circuit is enabled when LVDE in SPMSC1 is high and the trip voltage is selected
by LVDV in SPMSC2. The LVD is disabled upon entering any of the stop modes unless the LVDSE bit is
set. If LVDSE and LVDE are both set, then the MCU cannot enter 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 VLVDH 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. Once 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. LVDV is not altered when an LVD reset occurs.
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.
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Resets and Interrupts
Table 5-1. Interrupt Summary (MC9S08GB60)
Vector
Priority
Lower
Higher
Address
(High/Low)
$FFC0/FFC1
through
$FFCA/FFCB
Vector
Name
$FFCC/FFCD
Vrti
$FFCE/FFCF
Module
Source
Enable
Description
Unused Vector Space
(available for user program)
RTIF
RTIE
Viic
System
control
IIC
IICIS
IICIE
$FFD0/FFD1
Vatd
ATD
COCO
AIEN
$FFD2/FFD3
Vkeyboard
KBI
$FFD4/FFD5
Vsci2tx
SCI2
$FFD6/FFD7
Vsci2rx
SCI2
$FFD8/FFD9
Vsci2err
SCI2
$FFDA/FFDB
Vsci1tx
SCI1
$FFDC/FFDD
Vsci1rx
SCI1
$FFDE/FFDF
Vsci1err
SCI1
$FFE0/FFE1
Vspi
SPI
$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
$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)
LOLRE/LOCRE
ICG
$FFF8/FFF9
Vlvd
System control
LVDF
LVDIE
$FFFA/FFFB
Virq
IRQ
IRQIE
$FFFC/FFFD
Vswi
Core
IRQF
SWI
Instruction
COP
LVD
RESET pin
Illegal opcode
COPE
LVDRE
—
—
$FFFE/FFFF
Vreset
Systemcontrol
—
Real-time
interrupt
IIC control
AD conversion
complete
Keyboard pins
SCI2 transmit
SCI2 receive
SCI2 error
SCI1 transmit
SCI1 receive
SCI1 error
SPI
Low-voltage
detect
IRQ pin
Software
interrupt
Watchdog timer
Low-voltage
detect
External pin
Illegal opcode
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Real-Time Interrupt (RTI)
5.7 Real-Time Interrupt (RTI)
The real-time interrupt function can be used to generate periodic interrupts based on a divide of the
external oscillator during run mode. It can also be used to wake the MCU from stop2 using the internal
1-kHz reference, or from stop3 using either the internal reference or the external oscillator if it is enabled
in stop modes. The RTICLKS bit in the system real-time interrupt status and control register (SRTISC) is
used to select between these two modes of operation.
The SRTISC register includes a read-only status flag, a write-only acknowledge bit, and a 3-bit control
value (RTIS2:RTIS1:RTIS0) used to disable the clock source to the real-time interrupt or select one of
seven wakeup delays between 8 ms and 1.024 seconds. The 1-kHz clock source and therefore the
periodic rates have a tolerance of about ±30 percent. The RTI has a local interrupt enable, RTIE, to allow
masking of the real-time interrupt. It can be disabled by writing 0:0:0 to RTIS2:RTIS1:RTIS0 so the clock
source is disabled and no interrupts will be generated. See 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 five 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 On-Chip Memory of this reference manual for the
absolute address assignments for all registers. This section refers to registers and control bits only by
their names. An equate or header file provided by Freescale 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.
This section describes register and bit details for the MC9S08GB60. Although these descriptions are
representative of HCS08 devices, you should always refer to the data sheet for details about a specific
HCS08 device.
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Resets and Interrupts
5.8.1 Interrupt 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
Write:
Reset:
0
0
5
4
IRQEDG
IRQPE
0
0
3
2
IRQF
0
IRQACK
0
0
1
Bit 0
IRQIE
IRQMOD
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 just edges. When the IRQ pin is enabled as the IRQ input and is configured to detect
rising edges, the optional pullup resistor is reconfigured 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.
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 logic 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 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.
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Reset, Interrupt, and System Control Registers and Control Bits
5.8.2 System Reset Status Register (SRS)
This register includes seven read-only status flags to indicate the source of the most recent reset. When
a debug host forces reset by writing 1 to BDFR in the FBDFR 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.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
POR
PIN
COP
ILOP
0
ICG
LVD
0
Write:
Power-on reset:
Low-voltage reset:
Any other reset:
Writing any value to SRS address clears COP watchdog timer.
1
0
0
0
0
(1)
0
0
(1)
0
0
(1)
0
0
0
0
0
(1)
1
1
0
0
0
0
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. Since the internal supply voltage was ramping up
at the time, the low-voltage reset (LVR) status bit is also set to indicate that the reset occurred while
the internal supply was below the LVR threshold.
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.
LVD — Low Voltage Detect
If the LVDRE and LVDSE bits are set and the supply drops below the LVD trip voltage, an LVD reset
will occur. This bit is also set by POR.
1 = Reset caused by LVD trip or POR.
0 = Reset not caused by LVD trip or POR.
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Resets and Interrupts
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
BDFR(1)
Write:
Reset:
0
0
0
1
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 Integration Module Control Register (SBDFR)
BDFR Background Debug Force Reset
A serial background command such as WRITE_BYTE may be used to allow an external debug host
to force a target system reset. Writing logic 1 to this bit forces an MCU reset. This bit cannot be written
from a user program.
5.8.4 System Options Register (SOPT)
This register may be read at any time. Bits 3, 2, and 0 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.
Read:
Write:
Reset:
Bit 7
6
5
COPE
COPT
STOPE
1
1
0
4
1
3
2
0
0
0
0
1
Bit 0
BKGDPE
1
1
= Unimplemented or Reserved
Figure 5-5. System Options Register (SOPT)
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)
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Reset, Interrupt, and System Control Registers and Control Bits
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 PTD0/BKGD/MS pin to function as BKGD/MS. When the bit is clear, the
pin will function as PTD0, 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.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
REV3
REV2
REV1
REV0
ID11
ID10
ID9
ID8
0
0
0
0
(1)
Reset:
0
Read:
ID7
Reset:
0
0
(1)
(1)
(1)
0
0
ID6
ID5
ID4
ID3
ID2
ID1
ID0
0
0
0
0
0
1
0
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).
ID[11:0] — Part Identification Number
Each derivative in the HCS08 Family has a unique identification number. The 9S08GB/GT is hard
coded to the value $003.
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Resets and Interrupts
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:
5
RTIACK
Reset:
0
0
4
RTICLKS
RTIE
0
0
3
0
0
2
1
Bit 0
RTIS2
RTIS1
RTIS0
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 logic 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 1-kHz 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 Delay Selects
These read/write bits select the wakeup delay for the RTI. The clock source for the real-time interrupt
is a self-clocked source which oscillates at about 1 kHz, is independent of other MCU clock sources.
Using external clock source the delays will be crystal frequency divided by value in
RTIS2:RTIS1:RTIS0.
Table 5-2. Real-Time Interrupt Frequency
RTIS2:RTIS1:RTIS0
1-kHz Clock Source Delay(1)
0:0:0
0:0:1
0:1:0
0:1:1
1:0:0
1:0:1
1:1:0
1:1:1
Disable periodic wakeup timer
8 ms
32 ms
64 ms
128 ms
256 ms
512 ms
1.024 s
Using External Clock Source Delay
(crystal frequency)
Disable periodic wakeup timer
divide by 256
divide by 1024
divide by 2048
divide by 4096
divide by 8192
divide by 16384
divide by 32768
1. Normal values are shown in this column based on fRTI = 1 kHz. See the appropriate data sheet fRTI for
the tolerance on these values.
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Reset, Interrupt, and System Control Registers and Control Bits
5.8.7 System Power Management Status and Control 1 Register (SPMSC1)
This register is used to control actions associated with low VDD detection circuitry. If low-voltage detection
is enabled, by setting LVDE =1, bits 5-3 control the action associated with the low voltage detection. LVDF
is a flag, used to alert the occurrence of low voltage. LVDAC is used to acknowledge and clear LVDF.
Read:
Bit 7
6
LVDF
0
LVDACK
Write:
Reset:
5
0
0
4
3
2
LVDIE
LVDRE
LVDSE
LVDE
0
1
1
1
1
Bit 0
0
0
0
0
= Unimplemented or Reserved
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 logic 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).
LVDRE — Low-Voltage Detect Reset Enable
This read/write bit enables LVDF errors 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.
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Resets and Interrupts
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.
Bit 7
Read:
LVWF
Write:
Power-on reset:
LVD reset:
Any other reset:
6
0
LVWACK
0(1)
0(1)
0(1)
0
0
0
5
4
LVDV
LVWV
0
U
U
0
U
U
3
2
PPDF
0
PPDACK
0
0
0
= Unimplemented or Reserved
0
0
0
1
Bit 0
PDC
PPDC
0
0
0
0
0
0
U = Unaffected by reset
1. LVWF will be set not just in the case when VSupply transitions below the trip point but also 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 LVWF bit indicates the low voltage warning status.
Writing a logic 1 to LVWACK clears LVWF to a logic 0 if a low voltage warning is not present.
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 logic 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.
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Chapter 6
Central Processor Unit (CPU)
6.1 Introduction
The HCS08 CPU is the latest generation in a series of a CPU family that started in 1979 with the NMOS
(N-channel metal-oxide semiconductor) M6805 Family. Next Freescale developed the M146805 Family
using metal gate CMOS (complementary MOS). Eventually, this process was replaced by silicon gate
CMOS and Freescale developed the M68HC05 CPU. The next major step in this series was the
M68HC08 which significantly expanded the instruction set to allow more efficient C compilers. The current
HCS08 CPU has been developed using a new process-independent design methodology, allowing it to
keep pace with rapid developments in silicon processing technology.
Compared with the M68HC08 CPU, the HCS08 CPU added:
• New addressing modes for LDHX instruction:
– Extended addressing mode (EXT)
– Indexed — no offset (IX)
– Indexed — 8-bit offset (IX1)
– Indexed — 16-bit offset (IX2)
– Stack pointer relative — 8-bit offset (SP1)
• New addressing modes for STHX and CPHX instructions:
– Extended addressing mode (EXT)
– Stack pointer relative — 8-bit offset (SP1)
• New background (BGND) instruction
• Operating bus frequency increased to 20 MHz on first derivatives
• Instruction queue (or pipeline) to improve instruction throughput
The new addressing modes for instructions involving the 16-bit H:X register pair improve the efficiency of
C compilers. The BGND instruction is used only in debug situations to implement software breakpoints.
The instruction queue improves instruction throughput because it makes the opcode and one byte of
operand information available to the CPU immediately at the start of an instruction. Without the queue,
the CPU would have to spend the first few cycles of an instruction waiting for the program information to
be fetched into the CPU. On any change of flow — such as branch, jump, or interrupt — the CPU performs
three program fetches to fill this instruction queue. The instruction queue caused some changes in the
cycle counts and the order of operations within instructions compared to the M68HC08 CPU, but the
benefits from being able to start instructions sooner more than offset the costs for filling the queue on
changes of flow.
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Central Processor Unit (CPU)
6.2 Programmer’s Model and CPU Registers
Figure 6-1 shows the programmer’s model for the HCS08 CPU. These registers are not located in the
memory map of the microcontroller. They are built directly inside the CPU logic.
0
7
ACCUMULATOR
A
16-BIT INDEX REGISTER H:X
H INDEX REGISTER (HIGH)
15
8
INDEX REGISTER (LOW)
7
X
0
SP
STACK POINTER
0
15
PROGRAM COUNTER
7
0
CONDITION CODE REGISTER V 1 1 H I N Z C
PC
CCR
CARRY
ZERO
NEGATIVE
INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
TWO’S COMPLEMENT OVERFLOW
Figure 6-1. CPU Registers
6.2.1 Accumulator (A)
This general-purpose 8-bit register is the primary data register for the HCS08. Data can be read into A
from memory with a load accumulator (LDA) instruction or from the stack with a pull (PULA) instruction.
The data in A can be written into memory with a store accumulator (STA) or onto the stack with a push
(PSHA). Various addressing mode variations allow a great deal of flexibility in specifying the memory
location involved in a load or store instruction. Transfer instructions allow values to be transferred from A
to X (TAX), from X to A (TXA), from A to the CCR (TAP), or from the CCR to A (TPA). The P in TAP and
TPA stands for processor status. The nibble-swap A (NSA) instruction exchanges the high-order four bits
of A with the low-order four bits.
You can also perform mathematical, shift, and logical operations on the value in A as in ADD, SUB, ASLA,
RORA, INCA, DECA, AND, ORA, EOR, etc. In some of these instructions, such as INCA or ASLA, the
value in A is the only input operand and the result replaces the value in A. In other cases, such as ADD
or AND, there are two operands: the value in A and a second value from memory. The result of the
arithmetic or logical operation replaces the value in A.
Multiply and divide instructions use A as an operand and also store part of the result in A. MUL does an
unsigned multiply of A times X and stores the 16-bit result in X:A. DIV does an unsigned 16-bit by 8-bit
divide of H:A by X and stores the result in A and the remainder in H.
The decimal adjust A (DAA) instruction is used, after an ADD or ADC instruction involving two BCD
numbers, to correct the value in A to a valid 2-digit BCD number with a proper carry indication. For a more
detailed discussion of this instruction, refer to 6.5.2.4 BCD Arithmetic.
It should be apparent that the accumulator is a very busy register, so it would be helpful if some operations
could avoid using A. For instance, memory-to-memory move instructions (MOV) are helpful. DBNZ also
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Programmer’s Model and CPU Registers
helps because it allows a loop counter to be implemented in a memory variable rather than the
accumulator. The X register can also be used as a second general-purpose 8-bit data register in many
cases. Some arithmetic operations such as clear, increment, decrement, complement, negate, and shift
can also be used with the X register.
6.2.2 Index Register (H:X)
This 16-bit index register is actually two separate 8-bit registers (H and X). The indexed addressing
modes use H:X as a 16-bit base reference pointer and variations of indexed addressing allow an
instruction-supplied 16-bit offset, 8-bit offset, or no offset. Other variations of indexed addressing
automatically increment the 16-bit index register after the index is used to access a memory operand.
Refer to 6.3.6 Indexed Addressing Mode for a more detailed discussion of the indexed addressing mode.
The 8-bit X register (low-order half of H:X) can also be used as a general purpose data register. The
read-modify-write instructions (ASLX, ASRX, CLRX, COMX, DECX, INCX, LSLX, LSRX, NEGX, ROLX,
RORX, and TSTX) allow a subset of the ALU operations that can be performed on the accumulator. Be
careful not to try to use these instructions when you really want to affect the full 16-bit H:X index register
because these instructions only affect X. Consider the following instructions and sequences to get 16-bit
versions of 8-bit operations on X.
ldhx
aix
aix
cphx
#$0000
#1
#-1
#$0000
;16-bit
;16-bit
;16-bit
;16-bit
version
version
version
version
of
of
of
of
CLRX
INCX
DECX
TSTX
Load, store, push, and pull instructions are available for X with the same addressing mode variations as
the ones used for A. There are also load and store instructions for the 16-bit H:X register pair; however,
not as many different addressing modes are offered. There are push (PSHH) and pull (PULH) instructions
for H, and simple 2-instruction sequences can be used to push and pull the full 16-bit index register (H:X).
pshx
pshh
;push low half of H:X
;push high half of H:X
pulh
pulx
;pull high half of H:X
;pull low half of H:X
Sometimes the stack pointer value needs to be transferred to the H:X register pair so H:X can act as a
pointer to information on the stack. The stack pointer always points at the next available location on the
stack, but normally the index register should point directly at data. Because of this, the 16-bit value in SP
is incremented by one as it is transferred to H:X with a TSX instruction. Because of this adjustment, after
a TSX instruction H:X points at the last byte of data that was stacked. A complementary adjustment takes
place during a TXS instruction. (The value is decremented by one during TXS.) One way to think about
this is that the 16-bit address points at the next available stack location when it is in SP and to the last
byte of information that was stacked when it is in H:X.
For compatibility with the earlier M68HC05, interrupts do not save the H register on the stack. It is good
practice to include a PSHH instruction as the first instruction in interrupt service routines (to save H) and
to include a PULH instruction (to restore H) as the last instruction before the RTI that ends the service
routine. You may leave these instructions out if you are absolutely sure H is not altered in your interrupt
service routine, but be sure there are no AIX instructions or instructions that use the post-increment
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variation of indexed addressing because these instructions could cause H to change. Unless you really
can’t tolerate the extra two bytes of program space, one extra temporary byte on the stack, and five bus
cycles of execution time, it is much safer to simply include the PSHH and PULH as a matter of habit.
Multiply and divide instructions use X as an operand, and MUL also stores part of the result in X. MUL
does an unsigned multiply of A times X and stores the 16-bit result in X:A. DIV does an unsigned 16-bit
by 8-bit divide of H:A by X and stores the result in A and the remainder in H.
6.2.3 Stack Pointer (SP)
This 16-bit address pointer register is used by the CPU to automatically maintain a last-in-first-out (LIFO)
stack. When the CPU executes a jump- or branch-to-subroutine (JSR or BSR) instruction, it automatically
saves the return address on the stack. When the return-from-subroutine (RTS) instruction at the end of
the subroutine is executed, this return address is automatically recovered from the stack so execution
resumes where it left off when the subroutine was called. Since SP is a full 16-bit register, the stack may
be located anywhere in the memory map, and it may be any size up to the size of available RAM on the
chip.
The stack pointer always points at the next available location on the stack. When a value is pushed onto
the stack, it is written to the address pointed to by the SP and then SP is automatically decremented to
point at the next available location. When a value is pulled from the stack, SP is first incremented to point
at the most recent data that was pushed on the stack, and then the data is read from the address now
pointed to by SP. Notice that the data pointed to by SP is not changed in the process of pulling it from the
stack. If you were to look at memory below where SP is currently pointing, you would see old values that
were previously stored on the stack. When new values are pushed onto the stack, they over-write
whatever is in those memory locations. If RAM in the area of the stack was cleared during reset
initialization, the maximum depth that the stack has grown to can be seen by noticing which memory
locations are still clear.
For compatibility with the earlier M68HC05, SP is set to $00FF by reset. This is almost never where the
top of the stack in new HCS08 applications should be because the RAM in the area from the end of the
input/output (I/O) and control registers to $00FF is more valuable for frequently accessed variables. The
memory area from $0000 to $00FF can be accessed using the direct addressing mode which saves
program space and executes faster than general accesses to other memory locations.
Also for compatibility with the M68HC05, the reset stack pointer (RSP) instruction forces the low-order
half of SP to $FF. In the M68HC05, this forced SP to the same value ($00FF) it had after reset. RSP is
seldom used in the HCS08 because it doesn’t affect the high-order half of SP, and, therefore, it doesn’t
necessarily restore SP to its reset value.
In new HCS08 programs you would typically initialize SP to point at the highest address in the on-chip
RAM. Normally, the following 2-instruction sequence is included within the first few instructions of a reset
initialization routine.
ldhx
txs
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
Normally, RamLast is defined in an equate or header file that describes the particular HCS08 device used
in your application. RamLast+1 causes H:X to be loaded with the next higher address past the end of RAM
because the TXS instruction includes an automatic adjustment (decrement by 1) on the value during the
transfer. This adjustment makes SP point at the next available location on the stack. In this case, SP now
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points at the last (highest address value) location in RAM, and this will be the first location where data will
be stacked. The stack will grow toward lower addresses as values are pushed onto the stack.
When an interrupt is requested, the CPU saves the current contents of CPU registers on the stack so,
after finishing the interrupt service routine, processing can resume where it left off. Figure 6-2 shows the
order that CPU registers are saved on the stack in response to an interrupt. Before the interrupt, SP points
to the next available location on the stack. As each value is saved on the stack, the data is stored to the
location pointed to by SP and SP automatically is decremented to point at the next available location on
the stack. The return-from-interrupt (RTI) instruction that concludes the interrupt service routine restores
the CPU registers by pulling them from the stack in the reverse order. Refer to 6.4.2 Interrupts and 5.5
Interrupts for more detailed discussions of interrupts.
TOWARD LOWER ADDRESSES
UNSTACKING
ORDER
7
•
•
•
0
SP AFTER
INTERRUPT STACKING
5
1
4
2
3
3
2
4
PROGRAM COUNTER HIGH
1
5
PROGRAM COUNTER LOW
CONDITION CODE REGISTER
ACCUMULATOR
INDEX REGISTER (LOW BYTE X)
*
SP BEFORE
THE INTERRUPT
•
STACKING
ORDER
•
•
TOWARD HIGHER ADDRESSES
*High byte (H) of index register is not stacked.
Figure 6-2. Interrupt Stack Frame
For compatibility with the earlier M68HC05 CPU, interrupts do not save the H register on the stack. It is
good practice to include a PSHH instruction as the first instruction in your interrupt service routines (to
save H) and to include a PULH instruction (to restore H) as the last instruction before the RTI that ends
the service routine.
The add immediate value to SP (AIS) instruction may be used to allocate space on the stack for local
variables. Although this is most common in C programs, the technique is also useful for assembly
language programs. The following code example demonstrates allocation and deallocation of space for
local variables on the stack. There is a more detailed discussion of stack techniques in 6.5.6
Stack-Related Instructions.
"
ais
"
ais
#-5
"
#5
;allocate 5 bytes for locals
"
;deallocate local space
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SP-relative indexed addressing with 8-bit offset (SP1) or 16-bit offset (SP2) allows many instructions to
directly access the information on the stack. This is important for efficient C compilers and the same
techniques can be used in assembly language programs.
Push and pull instructions are similar to store and load instructions except they load or store the data
relative to the current SP value rather than accessing a specific memory location. The stack must always
be “balanced,” meaning that for every operation that places a byte of data on the stack, there must be a
corresponding operation that removes a byte of data. For each JSR or BSR, there should be an RTS. For
each interrupt or SWI, there should be an RTI. For each push, there should be a pull. If you allocate space
for locals with an AIS instruction, you should have a corresponding AIS instruction to deallocate the same
amount of space.
Suppose you had a subroutine that included a PSHA instruction, but you forgot to do a corresponding
PULA before returning from the subroutine. The return from subroutine (RTS) would not work correctly
because SP would not be pointing at the correct return address when RTS was executed.
Another error is a subroutine that calls itself, but doesn’t have a reliable way to limit the number of nesting
iterations. This produces a stack that grows beyond the space set aside for the stack. Usually this ends
when stack operations start storing things on top of RAM variables or I/O and control registers. This is
called stack overflow, and it can also happen when an interrupt service routine clears the I mask inside
the service routine which makes nested interrupts possible. Each level of nesting adds at least five more
bytes to the stack.
6.2.4 Program Counter (PC)
The program counter is a 16-bit register that contains the address of the next instruction or operand to be
fetched.
During normal 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 which is located at address $FFFE and
$FFFF. The vector is the address of the first instruction to be executed after exiting from the reset state.
6.2.5 Condition Code Register
The 8-bit condition code register contains the interrupt mask (I) and five status flags. Bit 6 and bit 5 are
permanently set to logic 1. The following paragraphs provide detailed information about the CCR bits and
how they are used. Figure 6-3 identifies the CCR bits and their bit positions.
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 6-3. Condition Code Register (CCR)
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The I bit is an interrupt mask control bit unlike the other bits in the CCR which are processor status bits.
The I bit is also the only one of the six implemented bits in the CCR to be initialized by reset. The I bit is
forced to 1 at reset so interrupts are blocked until you have initialized the stack pointer. The other five
status bits (V, H, N, Z, and C) are unknown after reset and will take on known values only after executing
an instruction that affects the bit(s). There is no reason to force these bits to a particular value at reset
because it would not make sense to do a conditional branch that used these bits unless you had just
executed an instruction that affected them.
The five status bits indicate the results of arithmetic and other instructions. Conditional branch instructions
will either branch to a new program location or allow the program to continue to the next instruction after
the branch, depending on the values in the CCR status bits. Simple conditional branch instructions (BCC,
BCS, BNE, BEQ, BHCC, BHCS, BMC, BMS, BPL, and BMI) cause a branch depending on the state of a
single CCR bit. Other branch instructions are controlled by a more complex combination of two or three
of the CCR bits. For example branch if less than or equal (BLE) branches if the Boolean expression [(Z)
| (N⊕V)] is true. The V bit (which was not present in the older M68HC05 instruction set) allows signed
branches because V is the two’s complement overflow indicator. Separate unsigned branch instructions
are based on the C bit which is effectively an overflow indicator for unsigned operations.
Often, the conditional branch immediately follows the instruction that caused the CCR bit(s) to be updated
as in this sequence:
more:
less:
cmp
blt
deca
#5
less
;compare accumulator A to 5
;branch if A<5
;do this if A not < 5
Other instructions may be executed between the test and the conditional branch as long as only
instructions that do not disturb the CCR bits that affect the conditional branch are used. A common
example is when a test is performed in a subroutine or function and the conditional branch is not executed
until the subroutine has returned to the main program. This is a form of parameter passing (that is,
information is returned to the calling program in the condition code bits). Consider the following example
which checks a character, received through the SCI, to see if it is the ASCII code for a valid hexadecimal
digit 0–9, a–f, or A–F.
"
goodHex:
errorHex:
"
"
lda
jsr
jsr
bne
nop
"
"
SCI1D
upcase
ishex
errorHex
"
"
;read character from SCI
;strip MSB & make upper case
;see if valid hex digit
;branch if char wasn't hex
;here if it was good hex digit
;here if it wasn't
"
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*********************
* ishex - check character for valid hexadecimal (0-9 or A-F)
* on entry A contains an unknown upper-case character
* returns with original character in A and Z set or cleared
* if A was valid hexadecimal, Z=1, otherwise Z=0
*********************
ishex:
psha
;save original character
cmp
#'0'
;check for < ASCII zero
blo
nothex
;branches if C=0 (Z also 0)
cmp
#'9'
;check for 0-9
bls
okhex
;branches if ASCII 0-9
cmp
#'A'
;check for < ASCII A
blo
nothex
;branches if C=0 (Z also 0)
cmp
#'F'
;check for A-F
bhi
nothex
;branches if > ASCII F
okhex:
clra
;forces Z bit to 1
nothex:
pula
;restore original character
rts
;return Z=1 if char was hex
*********************
Figure 6-4. Parameter Passing in CCR Bits
Three branch instructions could lead to the exit sequence at nothex and in each case the programmer
knows that the Z bit in the CCR would have to be 0 if the branch was taken. There are two ways to get to
okhex and in each case the Z bit could be either 0 or 1, so the CLRA instruction is used to force the Z bit
to be set to 1. The PULA and RTS instructions are executed after the tests that updated the Z bit but
before the BNE errorHex instruction that uses the Z value. This works because the programmer checked
the instruction set details to be sure PULA and RTS would not disturb the Z bit. This example shows that
it is just as important to know which instructions do not change CCR status bits as it is to know which
instructions do affect CCR status bits.
I — Interrupt Mask
The interrupt mask bit is a global interrupt mask that blocks all maskable interrupt sources while I = 1.
Reset forces the I bit to logic 1 to block interrupts until the application program can initialize the stack
pointer. If interrupts were allowed before the stack pointer was initialized, CPU register values could
get saved (written) to inappropriate memory locations. The user program can set or clear I using the
set interrupt mask (SEI) and clear interrupt mask (CLI) instructions, respectively.
The I bit is set automatically in response to any interrupt (including the SWI instruction) to prevent
unwanted nesting of interrupts. It is possible to explicitly allow nesting of interrupts in a controlled
manner by including a CLI instruction inside an interrupt service routine; however, this is not usually
recommended because it can lead to subtle system errors which are particularly difficult to find and
correct.
The WAIT and STOP instructions automatically clear the I bit because interrupts are the normal way
to wake up the CPU from stop or wait modes. These instructions could have been designed so a
separate CLI instruction was needed before executing WAIT or STOP. However, clearing I within these
instructions saves the program space and execution time the separate CLI would have required, and
prevents any possibility of an interrupt getting recognized after I is cleared but before the WAIT or
STOP instruction.
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When an interrupt occurs, The CCR value is saved on the stack before the I bit is automatically set (I
would be 0 in the stacked CCR value). When the return-from-interrupt (RTI) instruction is executed to
return to the main program, the act of restoring the CCR value from the stack normally clears the I bit.
When the I bit is set, the change takes effect too late in the instruction to prevent an interrupt at the
instruction boundary immediately following an SEI or TAP instruction. In the case of setting I with a
TAP or SEI instruction, I is actually set at the instruction boundary at the end of the TAP or SEI
instruction. In the case of clearing I with a TAP or CLI instruction, I is actually cleared at the instruction
boundary at the end of the TAP or SEI instruction. Because of this, the next instruction, after a CLI or
TAP that cleared I, will always execute even if an interrupt was already waiting when the CLI or TAP
that cleared I was executed. In the case of the RTI instruction, the CCR is restored during the first cycle
of the instruction so the 1-cycle delay, associated with clearing I, expires several cycles before the RTI
instruction finishes. WAIT and STOP also clear I in the middle of the instruction, so the delay expires
before actually entering wait or stop mode.
V — Two’s Complement Overflow Flag
This bit is set by the CPU when a two’s complement overflow results from an arithmetic operation on
signed binary values. For an addition operation, the V bit will be set if the sign (bit 7) is the same for
both operands that were being added, but different from the sign of the result. For a subtract or
compare operation, the V bit will be set if a positive number (bit 7=0) is subtracted from a negative
number (bit 7=1) and the result is positive, or if a negative number is subtracted from a positive number
and the result is negative.
The most common use of the V bit is to support the signed conditional branches (BLT, BLE, BGE, and
BGT) after executing a CMP, CPHX, CPX, SBC, or SUB instruction. These instructions cause the ALU
to subtract the contents of the referenced memory location (m) from the contents of a CPU register (r)
and to set or clear V, N, Z, and C according to the results. (C is used for unsigned branches but not for
signed conditional branches.) In the case of BLT, for example, the branch will be taken if the CPU
register (r) was less than the memory location (m).
Several other instructions affect the V bit, and a clever programmer can sometimes use the condition
of the V bit to control program flow. The Boolean formula for each affected CCR bit is given in the
instruction details in Appendix A Instruction Set Details.
The ADD and ADC instructions set V if both operands had the same sign and the sign of the result is
different. Since no simple branch instructions are based on V alone, a sequence of two instructions is
needed to test for two’s complement overflow after an add operation. You could say BGE to
no_overflow, followed by BMI to no_overflow, and falling through both of these branches implies there
was a signed overflow condition. Operations like this are not common, but they can be understood by
studying Boolean formulae and the Boolean equations for the branches in the instruction set detail
pages in Appendix A Instruction Set Details.
Arithmetic or logical shift left (ASL or LSL) is like multiplying a binary number by two. In this case, the
V bit will be set if the sign of the result is different from the original signed value. The meaning of V after
a right shift is less useful for signed arithmetic operations but could have some useful logical meaning
in some systems.
The DAA instruction can change the V bit, so don’t try to do a signed branch after a DAA instruction
without executing a new compare or subtract instruction.
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H — Half-Carry (Carry from Bit 3 to Bit 4)
The half-carry flag is intended for use with operations involving binary-coded-decimal (BCD) numbers.
A BCD number is a decimal number from 0 through 9 which is coded into a single 4-bit binary value.
This allows a single 8-bit value to hold exactly two BCD digits. The hexadecimal values $A through $F
are considered illegal BCD values. The ALU’s normal binary addition function can be used to add BCD
numbers, but the results need to be checked and corrected so the result is still a valid BCD value. In
the earlier M68HC08, the programmer had to do this checking and correction in a small program using
the BHCC and BHCS conditional branch instructions. The HCS08 includes the decimal adjust
accumulator (DAA) instruction to simplify the checking and correction operation into a single
instruction.
The H bit is affected only by a few instructions. RTI restores the H bit to the value it had before servicing
an interrupt. TAP allows the programmer to directly load all CCR bits with the contents of the
accumulator. The multiply instruction (MUL) clears H as a side effect of its operation so avoid using a
MUL instruction between an add operation and the DAA, BHCC, or BHCS instruction that needs the
H bit value.
The add instructions (ADD and ADC) are the only instructions that affect the H bit in a meaningful way.
These instructions set the H bit if there was a carry out of bit 3 into bit 4 of the result (from one BCD
digit to the next). Although BHCC and BHCS instructions could be used to build a program that restores
the result of an addition with BCD operands into a valid BCD result, it is more likely that you would use
the DAA instruction because it performs the whole checking and correction operation in a single
instruction. Refer to 6.5.2.4 BCD Arithmetic for a more detailed explanation of BCD arithmetic.
N — Negative Flag
This flag indicates that the most significant bit of the result was set (1). It is called the negative flag
because in two’s complement notation a number is said to be negative if its most significant bit is a
logic 1. If an operation involves 16-bit numbers (such as LDHX or CPHX), the N bit will be set if bit 15
of the result is set. In practice, this flag has many uses that are not related to signed arithmetic.
Branch if plus (BPL) and branch if minus (BMI) are simple branches which branch based solely on the
value in the N bit. The N bit is also used by the signed branches BLT, BLE, BGE, and BGT since it
indicates the sign of the result. All load, store, move, arithmetic, logical, shift, and rotate instructions
cause the N bit to be updated. TAP allows N to be set directly from the value in bit 2 of A, and RTI
restores N to the value that was saved on the stack when the interrupt service routine started.
The most significant bit of an I/O port, a control register, or a memory variable can be tested efficiently
because just loading data from or storing data to a location automatically updates the N bit. In the
following code fragment, a port is read where a switch is connected to bit 7. The N bit indicates whether
the switch was on or off without any further test.
swOn:
swOff:
lda
bmi
nop
PTAD
swOff
;read I/O port A
;branches if PTA7 was high
;here if MSB=0
;here if MSB=1 (sw off)
Z — Zero Flag
The Z bit is set to indicate the result of an operation was $00 (or $0000 if it was a 16-bit operation).
The related branch instructions are branch if equal (BEQ) and branch if not equal (BNE) because
compare instructions perform an internal subtraction of a memory operand from the contents of a CPU
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register. If the original operands were equal, the result of this internal subtraction would be 0 and Z
would be set to 1.
Branch if equal (BEQ) and branch if not equal (BNE) are simple branches which branch based solely
on the value in the Z bit. The Z bit is also used by the signed branches BLE and BGT and the unsigned
branches BLS and BHI. All load, store, move, arithmetic, logical, shift, and rotate instructions cause
the Z bit to be updated. TAP allows Z to be set directly from the value in bit 1 of A, and RTI restores Z
to the value that was saved on the stack when the interrupt service routine started.
Figure 6-4 shows an example where the Z bit is used to pass information back to a main program from
a subroutine. To understand this example, study how compare instructions affect CCR bits and the
Boolean formulae that are used by the branch instructions. This information is found in Appendix A
Instruction Set Details.
C — Carry (Out of Bit 7)
After an addition operation, the C bit is set if the source operands were both greater than or equal to
$80 or if one of the operands was greater than or equal to $80 and the result was less than $80. This
is equivalent to an unsigned overflow. A subtract or compare performs a subtraction of a memory
operand from the contents of a CPU register so after a subtract operation, the C bit is set if the
unsigned value of the memory operand was greater than the unsigned value of the CPU register. This
is equivalent to an unsigned borrow or underflow.
Branch if carry clear (BCC) and branch if carry set (BCS) are simple branches which branch based
solely on the value in the C bit. The C bit is also used by the unsigned branches BLO, BLS, BHS, and
BHI. Add, subtract, shift, and rotate instructions cause the C bit to be updated. After a divide
instruction, C is set if there was an attempt to perform an illegal divide-by-zero operation. TAP allows
C to be set directly from the value in bit 0 of A, and RTI restores C to the value that was saved on the
stack when the interrupt service routine started. The branch if bit set (BRSET) and branch if bit clear
(BRCLR) instructions copy the tested bit into the C bit to facilitate efficient serial-to-parallel conversion
algorithms. Set carry (SEC) and clear carry (CLC) allow the carry bit to be set or cleared directly. This
is useful in combination with the shift and rotate instructions and for routines that pass status
information back to a main program, from a subroutine, in the C bit.
The C bit is included in shift and rotate operations so those operations can easily be extended to
multibyte operands. The shift and rotate operations can be considered 9-bit shifts which include an
8-bit operand or CPU register and the carry bit of the CCR. After a logical shift, C holds the bit that was
shifted out of the 8-bit operand. If a rotate instruction is used next, this C bit is shifted into the operand
for the rotate, and the bit that gets shifted out the other end of the operand replaces the value in C so
it can be used in subsequent rotate instructions. Refer to 6.5.4 Shift and Rotate Instructions to see a
more detailed demonstration of this technique.
6.3 Addressing Modes
Whenever the MCU reads information from memory or writes information into memory, an addressing
mode is used to determine the exact address where the information is read from or written to. This section
explains several different ways to address memory, and each is useful in varying programming situations.
For instance, in some addressing modes, the address is determined by the assembler when the program
is written. Other addressing modes allow the address to be influenced by the contents of CPU registers.
This is important because it allows the address to be computed during execution of the program.
Every opcode tells the CPU to perform a certain operation in a certain way. Many instructions such as
load accumulator (LDA) allow several different ways to specify the memory location to be operated on,
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and each addressing mode variation requires a separate opcode. All of these variations use the same
instruction mnemonic, and the assembler knows which opcode to use based on the syntax of the operand
field. In some cases, special characters are used to indicate a specific addressing mode (such as the #
[pound] symbol which indicates immediate addressing mode). In other cases, the value of the operand
tells the assembler which addressing mode to use. For example, the assembler chooses direct
addressing mode instead of extended addressing mode if the operand address is between $0000 and
$00FF.
Some instructions use more than one addressing mode. For example, the move instructions use one
addressing mode to access the source value from memory and a second addressing mode to access the
destination memory location. For these move instructions, both addressing modes are listed in the
documentation. All branch instructions use relative (REL) addressing mode to determine the destination
for the branch, but BRCLR, BRSET, CBEQ, and DBNZ also need to access a memory operand. These
instructions are classified by the addressing mode used for the memory operand, and the relative
addressing mode for the branch offset is just assumed.
In the following paragraphs, the discussion includes how each addressing mode works and the syntax
clues the assembler uses to know that the programmer wants a specific addressing mode.
6.3.1 Inherent Addressing Mode (INH)
This addressing mode is used when the CPU inherently knows everything it needs to complete the
instruction, and no addressing information is supplied in the source code. Usually, the operands that the
CPU needs are located in the CPU’s internal registers, as in ASLA, CLRX, DAA, DIV, RSP, and others.
Instructions like clear carry bit (CLC) and set interrupt mask (SEI) affect a single bit within the CCR. A few
inherent instructions, including no operation (NOP) and background (BGND), have no operands.
Another group of instructions listed as inherent (INH) actually access memory based on the value of the
stack pointer. Instructions of this type include PSHx, PULx, RTI, RTS, and SWI. A purist could argue that
SWI uses a form of indexed addressing to push CPU register values onto the stack and extended
addressing to fetch the SWI vector, but since there is no program-supplied addressing information, it is
considered an inherent instruction.
6.3.2 Relative Addressing Mode (REL)
Relative addressing mode is used to specify the destination address for branch instructions. Typically, the
programmer specifies the destination with a program label or an expression in the operand field of the
branch instruction. The assembler calculates the difference between the location counter (which points at
the next address after the branch instruction at the time) and the address represented by the label or
expression in the operand field. This difference is called the offset and is an 8-bit two’s complement
number. The assembler stores this offset in the object code for the branch instruction.
During execution, the CPU evaluates the condition that controls the branch. If the branch condition is true,
the CPU sign-extends the offset to a 16-bit value, adds the offset to the current PC, and uses this as the
address where it will fetch the next instruction and continue execution rather than continuing execution
with the next instruction after the branch. Since the offset is an 8-bit two’s complement value, the
destination must be within the range –128 to +127 locations from the address that follows the last byte of
object code for the branch instruction.
A common method to create a simple infinite loop is to use a branch instruction that branches to itself.
This is sometimes used to end short code segments during debug. Typically, to get out of this infinite loop,
use the debug host (through background commands) to stop the program, examine registers and memory
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or to start execution from a new location. This construct is not used in normal application programs except
in the case where the program has detected an error and wants to force the COP watchdog timer to
timeout. (The branch in the infinite loop executes repeatedly until the watchdog timer eventually causes
a reset.)
6.3.3 Immediate Addressing Mode (IMM)
In this addressing mode, the operand is located immediately after the opcode in the instruction stream.
This addressing mode is used when the programmer wants to use an explicit value that is known at the
time the program is written. A # (pound) symbol is used to tell the assembler to use the operand as a data
value rather than an address where the desired value should be accessed.
The size (8 bits or 16 bits) of the immediate operand is assumed based on the size of the CPU register
indicated in the instruction. For example, a load A or add A instruction implies an 8-bit operand while a
load H:X or compare H:X instruction implies a 16-bit operand to match the width of the H:X register pair.
The assembler automatically will truncate or extend the operand as needed to match the size needed for
the instruction. Most assemblers generate a warning if a 16-bit operand is provided where an 8-bit
operand was expected.
A common programming error is to accidentally forget the # symbol before an immediate operand. In the
following example, the first instruction tells the assembler to compare the contents of the H:X register pair
to the address of tableEnd. Leaving the # symbol off in the second instruction tells the assembler to
compare the contents of the H:X register pair to the 16-bit value stored at tableEnd and tableEnd+1 (using
extended addressing mode).
182
183
184
185
C04A
C04D
C04F
C051
65
75
A6
B6
00BF
BF
55
55
cphx
cphx
lda
lda
#tableEnd
tableEnd
#$55
$55
;H:X points at end of table?
;compare to value at tableEnd
;load pattern $55 into A
;load A from address $0055
It is the programmer’s responsibility to use the # symbol to tell the assembler when immediate addressing
should be used. The assembler does not consider it an error to leave off the # symbol because the
resulting statement is still a valid instruction (although it may mean something different than the
programmer intended).
6.3.4 Direct Addressing Mode (DIR)
This addressing mode is used to access operands located in direct address space ($0000 through
$00FF). This is a more efficient addressing mode than extended addressing because the upper 8 bits of
the address are implied rather than being explicitly provided in the instruction. This saves a byte of
program space and the bus cycle that would have been needed to fetch this byte.
The programmer does not use any special syntax to choose this mode. Rather, the assembler evaluates
the label or expression in the operand field and automatically chooses direct addressing mode if the
resulting address is in the range $0000 through $00FF. During execution, the CPU gets the low byte of
the direct address from the operand byte that follows the opcode, appends a high byte of $00, and uses
this 16-bit address ($00xx) to access the intended operand.
Most of the I/O and control registers are located in the first 64 or 128 bytes of memory (a few rarely used
registers are located in high memory at $18xx). Some of the on-chip RAM is also located in the direct
page to allow frequently accessed variables to be located there so direct addressing can be used. After
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Central Processor Unit (CPU)
reset, the stack pointer points at $00FF and it is recommended that you change SP to point at the top of
RAM instead, to make the RAM below $00FF available for direct addressed variables.
6.3.5 Extended Addressing Mode (EXT)
In the extended addressing mode, the full 16-bit address of the operand is included in the object code in
the next two bytes after the opcode. This addressing mode can be used to access any location in the
64-Kbyte memory map. Normally, the programmer uses a program label to specify the address and the
assembler substitutes the equivalent 16-bit address as the program is assembled.
6.3.6 Indexed Addressing Mode
Indexed addressing mode is sometimes called indirect addressing mode because a CPU index register
is used as a reference, an offset is optionally added to the index reference, and the resulting address is
then used to access the intended operand. In some cases the value in the index register is incremented
automatically after the operand has been accessed. This can save programming steps by making the
index register point at the next operand in a list or by incrementing a loop count.
An important feature of indexed addressing mode is that the operand address is computed during
execution based on the then-current contents of a CPU index register rather than being a constant
address location that was determined during program assembly. This allows the programmer to write a
compact program loop that accesses successive values in a list or table on each pass through the loop.
It also allows a program to be written that accesses different operand locations depending on the results
of earlier program instructions (rather than accessing a location that was determined when the program
was written).
6.3.6.1 Indexed, No Offset (IX)
In this variation of indexed addressing, the content of the H:X index register pair is used as the address
of the operand to be accessed.
6.3.6.2 Indexed, No Offset with Post Increment (IX+)
In this variation of indexed addressing, the content of the H:X index register pair is used to access the
intended operand, and then the H:X register pair is incremented by one. CBEQ and MOV instructions are
the only instructions which use this addressing mode.
findSP:
ldhx
lda
cbeq
#stringBytes
#' '
x+,foundSP
foundSP:
bra
aix
findSP
#-1
;point at top of block
;pattern to search for
;found ASCII space ($20) ?
;H:X pointing at location after space
;keep looking
;back up to the space
6.3.6.3 Indexed, 8-Bit Offset (IX1)
In this variation of indexed addressing, an instruction-supplied unsigned 8-bit offset is added to the H:X
register pair to form the address of the operand to be accessed. The addition of the offset is an internal
calculation that does not affect the contents of H:X.
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6.3.6.4 Indexed, 8-Bit Offset with Post Increment (IX1+)
In this variation of indexed addressing, an instruction-supplied unsigned 8-bit offset is added to the H:X
register pair to form the address of the operand to be accessed. The addition of the offset is an internal
calculation that does not affect the contents of H:X. After the operand has been accessed, the H:X register
pair is incremented by one. CBEQ is the only instruction which uses this addressing mode.
6.3.6.5 Indexed, 16-Bit Offset (IX2)
In this variation of indexed addressing, an instruction-supplied unsigned 16-bit offset is added to the H:X
register pair to form the address of the operand to be accessed. The addition of the offset is an internal
calculation that does not affect the contents of H:X.
This addressing mode is particularly useful for addressing two data structures in different areas of
memory from a single index reference value in H:X. The following example demonstrates this technique.
199
200
201
202
203
204
205
206
C064
C067
C06A
C06C
C06F
C071
45
65
27
D6
71
9D
0088
0092
06
BF7F
F6
; string compare with one string in flash, the other in RAM (IX2)
ldhx
#moveBlk1
;point at string 1 in RAM
chkLoop:
cphx
#moveBlk1+10 ;see if past end
beq
stringOK
;if so, you are done
lda
(stringBytes-moveBlk1),x ;load from flash
cbeq
x+,chkLoop
;compare to byte in flash
stringBad:
nop
;here if string didn't match
stringOK:
;here if it did
In the example, the two data structures have similar structures. One is in RAM and holds current data
values. The second data structure is a set of constant values in FLASH memory. The assembler
computes the expression (stringBytes–moveBlk1) to get the 16-bit offset from moveBlk1 in RAM to
stringBytes in flash. As the index is incremented (in the CBEQ instruction), the LDA
(stringBytes-moveBlk1),X accesses the next byte from stringBytes and CBEQ 0,X+,chkLoop accesses
the next byte from moveBlk1 in RAM.
6.3.6.6 SP-Relative, 8-Bit Offset (SP1)
In this variation of indexed addressing, an instruction-supplied unsigned 8-bit offset is added to the stack
pointer (SP) to form the address of the operand to be accessed. The addition of the offset is an internal
calculation that does not affect the contents of SP. Note that the SP points at the next available location
on the stack rather than the last value that was pushed onto the stack, so read operations with an offset
of zero are normally not useful.
Stack pointer relative addressing is most commonly used to access parameters and local variables on the
stack. This is a common practice for compiled C code. Depending on the number of stack relative
accesses and what the H:X register pair is being used for, the compiler will sometimes temporarily save
the current H:X value and move SP into H:X to allow indexed addressing from H:X rather than SP
because SP-relative addressing typically takes an extra cycle and byte of program space compared to
H:X-relative addressing.
209
210
211
212
213
214
215
C072 A7 FD
C074
C077
C07A
C07C
9E6F 02
9E6F 03
A6 04
9EE7 01
ais
#-3
;space for 3 bytes of locals
; sp+1 is a byte sized local
; sp+2:sp+3 is a 16-bit local (an integer variable)
clr
2,sp
;clear high byte of local int
clr
3,sp
;clear low byte of local int
lda
#4
sta
1,sp
;set local byte to 4
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217
218
219
220
221
222
223
224
C07F
C081
C082
C084
C086
C088
A7
95
6F
6F
A6
F7
FD
01
02
04
; tsx & index based on H:X to save code size comapred to previous
; tsx cost 1 byte but saved 4 (overall savings equal 3 bytes)
ais
#-3
;space for 3 bytes of locals
tsx
;H:X <- SP+1
clr
1,x
;clear high byte of local int
clr
2,x
;clear low byte of local int
lda
#4
sta
,x
;set local byte to 4
6.3.6.7 SP-Relative, 16-Bit Offset (SP2)
In this variation of indexed addressing, an instruction-supplied unsigned 16-bit offset is added to the stack
pointer (SP) to form the address of the operand to be accessed. The addition of the offset is an internal
calculation that does not affect the contents of SP. Note that the SP points at the next available location
on the stack rather than the last value that was pushed onto the stack.
This addressing mode is used to access data that is more than 255 locations deep in the stack. If the offset
is 255 or less, the assembler will automatically use the more efficient SP1 addressing mode.
6.4 Special Operations
Most of what the CPU does is described by the instruction set, but a few special operations need to be
considered, such as how the CPU gets started at the beginning of an application program after power is
first applied. Once the program is running, the current instruction normally determines what the CPU will
do next. A few exceptional events can cause the CPU to temporarily suspend normal program execution.
Reset events force the CPU to start over at the beginning of the application program as directed by the
contents of the reset vector. Hardware interrupts can come from external pins or from internal peripheral
modules. These interrupts cause the CPU to complete the current instruction and then respond to the
interrupt rather than continuing to the next instruction in the application program. Finally, a host
development system can cause the CPU to go to active background mode rather than continuing to the
next instruction in the application program.
Wait and stop modes are activated as the result of the WAIT and STOP instructions, respectively;
however, these special instructions also affect other systems in the microcontroller (MCU). While these
modes are active, CPU activity is suspended indefinitely until some hardware event occurs to wake up
the MCU.
6.4.1 Reset Sequence
Processing begins at the trailing edge of a reset event. The number of things that can cause reset events
can vary slightly from one HCS08 derivative to another; however, the most common sources are
power-on reset, the external RESET pin, low-voltage reset, COP watchdog timeout, illegal opcode detect,
and illegal address access. For more information about how the MCU recognizes reset events and
determines the differences between internal and external causes, refer to Chapter 5 Resets and
Interrupts. For detailed information about all of the possible causes of reset in a particular HCS08
derivative, refer to the appropriate technical data sheet.
Reset events force the MCU to immediately stop what it is doing and begin responding to reset. Any
instruction that was in process will be aborted immediately without completing any remaining clock cycles.
A short sequence of activities is completed to decide whether the source of reset was internal or external
and to record the cause of reset. For the remainder of the time the reset source remains active, the
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Special Operations
internal clocks are stopped to save power. At the trailing edge of the reset event, the clocks resume and
the CPU exits from the reset condition.
The CPU performs a 6-cycle sequence to exit reset before starting the first program instruction. The
high-order byte of the reset vector is fetched from $FFFE and stored in the high-order byte of the program
counter. The low-order byte of the reset vector is fetched from $FFFF and stored in the low-order byte of
the program counter. The next bus cycle is a free cycle where the CPU does not access memory because
the low-order half of the vector is not yet available to the CPU. Whenever the CPU performs a memory
read operation, there is a 1 cycle delay before the data has time to propagate into the CPU where it can
be used in any subsequent operation. Next, the CPU places the program counter address on the bus to
fetch the first byte of program information and then increments the program counter. (The program
counter contained the reset vector that was just fetched from $FFFE, FFFF.) The next cycle (fifth in the
reset sequence) fetches the second byte of program information into the instruction queue, and the next
cycle (last in the reset sequence) accesses the third byte of program information so it is on its way into
the instruction queue.
After the 6-cycle reset sequence, two bytes of program information are available to the CPU in the
instruction queue and a third byte is on its way. Notice that MCU operations form a continuous stream of
activity and different parts of the system see different events within this stream at any particular instant in
time. To avoid confusion, the user’s perception of a bus cycle is used as the single point of reference for
all further discussions. See 6.4.6 User’s View of a Bus Cycle.
6.4.2 Interrupts
As the name implies, interrupts interrupt the normal flow of instructions. Except for the SWI instruction,
interrupts are caused by hardware events and are generally asynchronous to the operating program. The
software interrupt instruction (SWI) behaves like other interrupts except that it is not maskable (cannot be
inhibited by the I bit in the CCR being 1).
When an interrupt is requested, the CPU 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, and filling the
instruction queue with the first three bytes of program information for the interrupt service routine. For
more information about how the MCU recognizes and processes interrupts, refer to Chapter 5 Resets and
Interrupts.
The interrupt mask bit (I bit) in the CCR acts as a global interrupt mask. When I is 1, interrupt requests
are ignored by the CPU. Immediately after reset, the I bit is 1 so that interrupts are disabled. Before
clearing the I bit to enable interrupts, initialize the stack pointer.
For compatibility with the earlier M68HC05 Family, the stack pointer is automatically initialized to $00FF
at reset. This is rarely where you want the stack to be located in an HCS08 system because this would
cause the stack to use valuable direct address space (the space from $0000 through $00FF). Usually, the
stack pointer should be set to point at the highest address in the on-chip RAM. Since there isn’t a load
stack pointer instruction, load H:X with the address of the last RAM location plus one, and then transfer
this value to SP. There is an automatic adjustment of the 16-bit value as it is transferred from H:X to SP
so the stack pointer will point at the next available location on the stack (in this case, so H:X points at the
last location in the on-chip RAM). Refer to 6.2.3 Stack Pointer (SP) for a more detailed explanation of the
stack pointer.
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Central Processor Unit (CPU)
Again for compatibility with the earlier M68HC05, the HCS08 does not stack the high-order half of the
index register (H) in response to an interrupt. In rare cases, you can choose not to stack H inside the
interrupt service routine if you are absolutely sure the service routine will never alter H. Many instructions,
including AIX and post-increment indexed addressing versions of instructions, can cause H to change.
Therefore, it is generally safer to include a PSHH instruction as the first instruction in the interrupt service
routine and a PULH instruction as the last instruction before the RTI that ends the service routine.
6.4.3 Wait Mode
Wait mode is entered by executing a WAIT instruction. This instruction clears the I bit in the CCR (so
interrupts can wake up the MCU from wait mode), and then shuts down the clocks in the CPU to save
power. The CPU remains in this low-power state until an interrupt or reset event wakes it up. For more
detailed information about wait mode, refer to 3.5 Wait Mode.
6.4.4 Stop Mode
Stop mode is entered by executing a STOP instruction. This instruction clears the I bit in the CCR (so
interrupts can wake up the MCU from stop mode), and then shuts down the clocks in the CPU to save
power. Depending on other control settings in the MCU, the system oscillator may be completely disabled
to reduce power consumption even further. The CPU remains in this low-power state until an interrupt or
reset event wakes it up. The wakeup sequence depends on whether the oscillator was completely
stopped, and what type of clock generation system is controlling the particular derivative. For more
detailed information about stop mode, refer to 3.6 Stop Modes.
6.4.5 Active Background Mode
Active background mode refers to the condition where the CPU has stopped executing user program
instructions and is waiting for serial commands from the background debug system. The CPU cannot
enter active background mode unless it has been enabled by a serial WRITE_CONTROL command
which has set the ENDBM bit in the BDCSCR. (BDCSCR is a status and control register within the
background debug controller (BDC) and is not accessible from the user program.) The usual way the CPU
gets into active background mode is in response to a BACKGROUND command through the serial
background communication interface (BKGD pin). The CPU can also enter active background mode due
to a reset event where the BKGD pin is held low at the trailing edge of reset, due to a BGND instruction,
or in response to a hardware breakpoint event.
Reset with BKGD low provides a way for a development system to gain control of a target MCU
immediately after reset before any user reset vector is fetched and before any user instructions are
executed. This is important in systems where the program memory and vectors are not yet programmed.
BGND instructions are used only by development systems to set software breakpoints and should never
be used in normal application programs. If a program runaway condition causes the CPU to encounter a
BGND instruction when no development system is connected to the BKGD pin, ENBDM would be 0 and
the BGND instruction would be treated as an illegal opcode.
The hardware breakpoint that is built into the BDC system is only accessible by serial commands through
BKGD, so this breakpoint would only occur if a development system is connected to BKGD and
ENBDM = 1.
Some HCS08 MCUs can have additional hardware breakpoints built outside the CPU and BDC systems.
These hardware breakpoints can be controlled by user programs as well as development systems. If this
type of hardware breakpoint is encountered while ENBDM = 1, the CPU completes the current instruction
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Instruction Set Description by Instruction Types
and then enters active background mode. If this type of hardware breakpoint is encountered while
ENBDM = 0, the CPU will execute an SWI instruction rather than trying to execute an illegal BGND
instruction. With proper planning, this mechanism can be used to allow a form of ROM patching. Refer to
7.5.9 Hardware Breakpoints and ROM Patching.
The CPU can remain in the active background mode indefinitely until a serial GO, TRACE1, or TAGGO
command causes it to return to the user’s application program. In a 3-cycle sequence on exit from active
background mode, the CPU does three program fetches to fill the instruction queue. There is no way for
the CPU to know whether the development system has altered program memory, so the CPU always
refills the instruction queue upon exit from active background mode.
6.4.6 User’s View of a Bus Cycle
In modern microcontrollers, operations are pipelined such that different parts of the circuit can be working
on different information at any particular instant in time. To avoid confusion, it is important to have a single
consistent point of reference so other system timing can be related to this common reference. This
common reference point for the HCS08 is a bus cycle. A read bus cycle is considered to begin with the
CPU internally generating an address which is then presented to the internal address bus. The addressed
memory location then places the requested data on the internal data bus after a memory access time. A
write cycle begins like a read cycle, with the CPU internally generating an address which is then presented
to the internal address bus. Next the data to be written is presented to the internal data bus and remains
valid long enough for the memory access to be completed.
Since these internal activities are not directly visible from the outside of the chip, we must relate this to an
external event such as the trailing edge of a reset event. The cycle-by-cycle sequence for the reset
operation is vvfppp where the first two v cycles are the bus cycles where the upper and lower bytes of the
reset vector are fetched from $FFFE and $FFFF, respectively. The f cycle is a free cycle where the CPU
does not use the internal buses. The three p cycles are used to fill the instruction queue with the first three
bytes of object code for the user program beginning at the address just fetched from the reset vector.
From this point, a user can tell exactly what should be on the internal buses for every bus cycle of a
program because every CPU instruction and exception event has a known sequence of bus cycles.
The exit from reset is synchronized to an internal bus clock so there is an uncertainty of up to one bus
cycle from the actual release of the active low at the reset pin and when the first v cycle starts. There is
a propagation delay from the external oscillator input (if present) to the internal bus clock which is not
specified because the user cannot access the internal bus clock to make a measurement.
6.5 Instruction Set Description by Instruction Types
In this section, the instructions are listed by types of instructions. Explanations of how these instructions
can be used within the context of an application program are provided. Example code segments are used
to show practical examples of common programming constructs.
6.5.1 Data Movement Instructions
This group of instructions is used to move data between memory and CPU registers, between memory
locations, or between CPU registers. Load, store, and move instructions automatically update the
condition codes based on the value of the data. This allows conditional branching with BEQ, BNE, BPL,
and BMI immediately after a load, store, or move instruction without having to do a separate test or
compare instruction.
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6.5.1.1 Loads and Stores
LDA
LDA
LDA
LDA
LDA
LDA
LDA
LDA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
LDHX
LDHX
LDHX
LDHX
LDHX
LDHX
LDHX
#opr16i
opr8a
opr16a
,X
oprx16,X
oprx8,X
oprx8,SP
LDX
LDX
LDX
LDX
LDX
LDX
LDX
LDX
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
STA
STA
STA
STA
STA
STA
STA
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
STHX opr8a
STHX opr16a
STHX oprx8,SP
STX
STX
STX
STX
STX
STX
STX
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Object Code
Effect
on CCR
V11H INZC
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
3
4
5
5
6
5
5
ppp
rrpp
prrpp
prrfp
pprrpp
prrpp
prrpp
0 1 1 – – –
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 1 1 – – –
ee ff
ff
3
4
4
3
2
5
4
DIR
EXT
SP1
35 dd
96 hh ll
9E FF ff
4
5
5
wwpp
pwwpp
pwwpp
0 1 1 – – –
DIR
EXT
IX2
IX1
IX
SP2
SP1
BF
CF
DF
EF
FF
9E DF
9E EF
dd
hh ll
ee ff
ff
3
4
4
3
2
5
4
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 1 1 – – –
A6
B6
C6
D6
E6
F6
9E D6
9E E6
ii
dd
hh ll
ee ff
ff
Load Index Register (H:X)
H:X ← (M:M + $0001)
IMM
DIR
EXT
IX
IX2
IX1
SP1
jj kk
dd
hh ll
9E
9E
9E
9E
45
55
32
AE
BE
CE
FE
Load X (Index Register Low) from Memory
X ← (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AE
BE
CE
DE
EE
FE
9E DE
9E EE
ii
dd
hh ll
ee ff
ff
DIR
EXT
IX2
IX1
IX
SP2
SP1
B7
C7
D7
E7
F7
9E D7
9E E7
dd
hh ll
ee ff
ff
Store H:X (Index Reg.)
(M:M + $0001) ← (H:X)
Store X (Low 8 Bits of Index Register)
in Memory
M ← (X)
Store Accumulator in Memory
M ← (A)
Cyc-by-Cyc
Details
2
3
4
4
3
3
5
4
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
Load Accumulator from Memory
A ← (M)
Cycles
Source
Form
Address
Mode
Table 6-1. Load and Store Instructions
ee ff
ff
ee ff
ff
ff
ee ff
ff
ee ff
ff
Load A and load X cause an 8-bit value to be read from memory into accumulator A or into the X register.
Load H:X causes one 8-bit value to be read from memory into the H register and a second 8-bit value to
be read from the next sequential memory location into the X register. Load A and load X each allow eight
different addressing modes for maximum flexibility in accessing memory. LDHX allows seven different
addressing modes to specify the memory locations of the values being read.
The following instructions demonstrate some of the uses for load instructions. This collection of
instructions is not intended to be a meaningful program. Rather, they are unrelated load instructions to
demonstrate the many possible addressing modes that allow access to memory in different ways.
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Freescale Semiconductor
Instruction Set Description by Instruction Types
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
C089
C08B
C08D
C08F
C091
C093
C095
C097
C09A
C09D
C0A0
; load A - various addressing modes
; immediate (IMM) addressing mode examples
A6 55
lda
#$55
;IMM - $ means hexadecimal
A6 64
lda
#100
;decimal 100 (hexadecimal $64)
A6 3F
lda
#%00111111
;% means binary
A6 41
lda
#'A'
;single quotes around ASCII
A6 8D
lda
#illegalOp
;label used as immediate value
; direct (DIR) addressing mode examples
B6 55
lda
$55
;load from address $0055
B6 9D
lda
directByte
;label as a direct address
; extended (EXT) addressing mode
C6 FFFE
lda
$FFFE
;high byte of reset vector
C6 0101
lda
extByte
;label used as an address
C6 C09D
lda
*
;* means "here", loads opcode
C6 009D
lda
fwdRef
;forces ext addressing mode
; not all assemblers treat forward references the same way
0000 009D fwdRef:
equ
directByte
;forward referenced direct
C0A3 45 C007
C0A6 D6 4081
C0A9 E6 01
C0AB F6
ldhx
#stringBytes ;point at string in flash
; indexed addressing mode (relative to H:X index register pair)
lda
(moveBlk1-stringBytes),x ;IX2 mode
lda
1,x
;IX1 - 8-bit offset
lda
,x
;IX - no offset
C0AC
C0AF
C0B0
C0B4
; indexed addressing mode (relative to SP stack pointer)
ldhx
#1
txs
;temp move SP for 16-bit offset ex.
lda
300,sp
;SP2 - 16-bit offset
lda
1,sp
;SP1 - 8-bit offset
45 0001
94
9ED6 012C
9EE6 01
Since one operand input to the arithmetic logic unit (ALU) is connected to the A accumulator, you typically
need to use an LDA instruction to read one value into A before performing mathematical or logical
operations involving a second operand.
; add A + B (assumes sum is < or = 255)
lda
oprA
;oprA -> accumulator
add
oprB
;oprA + oprB -> accumulator
In some cases, you can plan your program so that the results that were stored in accumulator A as the
result of one operation can be used as an operand in a subsequent operation. This can save the need to
store one result and reload the accumulator with the next operand.
; add A + B + C (assumes sum is < or = 255)
lda
oprA
;oprA -> accumulator
add
oprB
;oprA + oprB -> accumulator
add
oprC
;accum. + oprC -> accum.
The next example shows an intermediate value being saved on the stack. This is sometimes faster than
storing temporary results in memory. The amount of savings depends on what addressing mode would
be needed to store the temporary value in memory and whether the X register was needed for something
else at the time.
; compute (A + B) - (C + D) (assumes no carry or borrow)
lda
oprC
;oprC -> accumulator
add
oprD
;oprC + oprD -> accumulator
psha
;intermediate result to SP+1
lda
oprA
;oprA -> accumulator
add
oprB
;oprA + oprB -> accumulator
sub
1,sp
;(A+B)-(C+D) to accumulator
ais
#1
;deallocate local space
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
99
Central Processor Unit (CPU)
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-2. BSET, BCLR, Move, and Transfer Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
Set Bit n in Memory (Mn ← 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– 1 1 – – – – –
BCLR n,opr8a
Clear Bit n in Memory
(Mn ← 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– 1 1 – – – – –
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
Move
(M)destination ← (M)source
In IX+/DIR and DIR/IX+ Modes,
H:X ← (H:X) + $0001
DIR/DIR
DIR/IX+
IMM/DIR
IX+/DIR
4E
5E
6E
7E
dd dd
dd
ii dd
dd
5
5
4
5
rpwpp
rfwpp
pwpp
rfwpp
0 1 1 – – –
TAX
Transfer Accumulator to X (Index Register
Low)
X ← (A)
INH
97
1
p
– 1 1 – – – – –
TXA
Transfer X (Index Reg. Low) to Accumulator
A ← (X)
INH
9F
1
p
– 1 1 – – – – –
TAP
Transfer Accumulator to CCR
CCR ← (A)
INH
84
1
p
1 1 TPA
Transfer CCR to Accumulator
A ← (CCR)
INH
85
1
p
– 1 1 – – – – –
NSA
Nibble Swap Accumulator
A ← (A[3:0]:A[7:4])
INH
62
1
p
– 1 1 – – – – –
BSET n,opr8a
6.5.1.2 Bit Set and Bit Clear
Bit set (BSET) and bit clear (BCLR) instructions can be thought of as bit-sized store instructions, but these
instructions actually read a full 8-bit location, modify the specified bit, and then re-write the whole 8-bit
location. In certain cases, such as when the target location is something other than a RAM variable, this
subtle behavior can lead to unexpected results. If a BSET or BCLR instruction attempts to change a bit
in a nonvolatile memory location, naturally, the bit will not change because nonvolatile memories require
a more complex sequence of operations to make changes.
Some status bits are cleared by a sequence involving a read of the status bit followed by a write to another
register in the peripheral module. Some users are surprised to find that a BSET or BCLR instruction has
satisfied the requirement to read the status register. To avoid such problems, just remember that the
BSET and BCLR instructions are read-modify-write instructions that access a full 8-bit location in parallel.
HCS08 Family Reference Manual, Rev. 2
100
Freescale Semiconductor
Instruction Set Description by Instruction Types
Some control or I/O registers do not access the same physical logic states for reads and writes. In
general, do not use read-modify-write instructions on these locations because they may produce
unexpected results.
276
277
278
279
280
281
C0D3 16 1B
C0D5 B6 1B
C0D7 AA 08
C0D9 B7 1B
; BSET example - turns on TE without changing RE
bset
TE,SCI1C2
;enable SCI transmitter
; functionally equivalent to...
lda
SCI1C2
;read current SCCR2 value
ora
#mTE
;OR in TE bit (mask)
sta
SCI1C2
;upate value in SCCR2
6.5.1.3 Memory-to-Memory Moves
Move instructions can be helpful in an accumulator architecture like the HCS08 where the number of
registers is limited. MOV performs a read of an 8-bit value from one memory location and stores the value
in a different location. Like the load and store instructions, MOV causes the N and Z bits in the CCR to be
updated according to the value of the data being moved.
Although load and store instructions could be used to do the same thing as a MOV instruction, MOV does
not require the accumulator to be saved so that A can be used as the transport means for the move
operation. In many cases, the MOV approach is faster and smaller (object code size) than the load-store
combination. MOV allows four different address mode combinations to specify the source and destination
locations for the move.
The following example shows how move instructions can be used to initialize several register values.
284 C0DB 6E 03 00
285 C0DE 6E 0F 03
286 C0E1 6E F0 01
mov
mov
mov
#$03,PTAD
#$0F,PTADD
#$F0,PTAPE
;0011 to 4 LS bits
;make 4 LS bits outputs
;pullups on 4 MS bits
The next example shows a string move operation using load and store instructions rather than move
instructions.
288
289
290
291
292
293
294
295
C0E4
C0E7
C0EA
C0EC
C0ED
C0EE
45
D6
27
F7
5C
20
0088
BF7F
04
F7
; block move example to move a string to a RAM block
ldhx
#moveBlk1
;point at destination block
movLoop1:
lda
(stringBytes-moveBlk1),x ;get source byte
beq
dunLoop1
;null terminator ends loop
sta
,x
;save to destination block
incx
;next location (assumes DIR)
bra
movLoop1
;continue loop
dunLoop1:
6.5.1.4 Register Transfers and Nibble Swap
TAX and TXA offer an efficient way to transfer a value from A to X or from X to A. Depending on whether
the X register is already being used, this can be an efficient way to temporarily save the accumulator value
so A can be used for some other operation.
TAP and TPA provide a means for moving the value from A into the CCR (processor status byte) or from
the CCR into A. This is used more in development tools like debug monitors than in normal user
programs.
The nibble swap A (NSA) instruction exchanges the upper and lower nibbles of the accumulator (A). An
8-bit value is called a byte and a nibble is the upper- or lower-order four bits of a byte. Each nibble
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
101
Central Processor Unit (CPU)
corresponds to exactly one hexadecimal digit. This instruction is useful for conversions between binary
or hexadecimal and ASCII, and for operations on binary-coded-decimal (BCD) numbers.
*********************
* chexl - convert upper nibble of A to ASCII
* chexr - convert lower nibble of A to ASCII
* on entry A contains any binary (hexadecimal) number
* returns with resulting ASCII character in A
*********************
chexl:
nsa
;swap nibble into low half
chexr:
and
#$0F
;strip off upper nibble
add
#$30
;now $30 - $3F
cmp
#$39
;check for < or = '9'
bls
dunChex
;if so, just return
add
#7
;adjust to $41-$46
dunChex:
rts
;return with ASCII in A
*********************
6.5.2 Math Instructions
Math instructions include the traditional add, subtract, multiply, and divide operations, a collection of utility
instructions including increment, decrement, clear, negate (two’s complement), compare, and test, and a
decimal adjust instruction for computations involving BCD numbers. The compare instructions are
actually subtract operations where the CCR bits are affected but the result is not written back to a CPU
register. The test instructions affect the N and Z condition code bits, but do not affect the tested value.
6.5.2.1 Add, Subtract, Multiply, and Divide
ADC
ADC
ADC
ADC
ADC
ADC
ADC
ADC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ADD
ADD
ADD
ADD
ADD
ADD
ADD
ADD
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
AIS #opr8i
Operation
Add with Carry
A ← (A) + (M) + (C)
Add without Carry
A ← (A) + (M)
Add Immediate Value (Signed) to
Stack Pointer
SP ← (SP) + (M)
Object Code
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A9
B9
C9
D9
E9
F9
9E D9
9E E9
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AB
BB
CB
DB
EB
FB
9E DB
9E EB
ii
dd
hh ll
ee ff
ff
IMM
ee ff
ff
ee ff
ff
A7 ii
Cycles
Source
Form
Address
Mode
Table 6-3. Add, Subtract, Multiply, and Divide Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – 2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – 2
pp
– 1 1 – – – – –
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102
Freescale Semiconductor
Instruction Set Description by Instruction Types
AIX #opr8i
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
SBC
SBC
SBC
SBC
SBC
SBC
SBC
SBC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Object Code
Add Immediate Value (Signed) to
Index Register (H:X)
H:X ← (H:X) + (M)
IMM
Subtract
A ← (A) – (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A0
B0
C0
D0
E0
F0
9E D0
9E E0
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A2
B2
C2
D2
E2
F2
9E D2
9E E2
ii
dd
hh ll
ee ff
ff
Subtract with Carry
A ← (A) – (M) – (C)
AF ii
ee ff
ff
ee ff
ff
Cycles
Source
Form
Address
Mode
Table 6-3. Add, Subtract, Multiply, and Divide Instructions (Continued)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
2
pp
– 1 1 – – – – –
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – 2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – MUL
Unsigned multiply
X:A ← (X) × (A)
INH
42
5
ffffp
– 1 1 0 – – – 0
DIV
Divide
A ← (H:A)÷(X); H ← Remainder
INH
52
6
fffffp
– 1 1 – – – The ADD instructions add the value in A to a memory operand and store the result in A. ADC adds the
value in A, plus the carry bit from a previous operation, to a memory operand and stores the result in A.
This operation allows performance of multibyte additions as demonstrated by the following example.
; add 8-bit operand
lda
add
sta
lda
adc
sta
lda
adc
sta
to 24-bit sum
oprA
;8-bit operand to A
sum24+2
;LS byte of 24-bit sum
sum24+2
;update LS byte
sum24+1
;middle byte of 24-bit sum
#0
;propigate any carry
sum24+1
;update middle byte
sum24
;get MS byte of 24-bit sum
#0
;propigate carry into MS byte
sum24
;update MS byte
The AIX instruction adds a signed 8-bit value to the 16-bit H:X index register pair and stores the result
back into H:X. Unlike other arithmetic instructions, AIX does not affect the CCR bits.
ldhx
#tblOfStruct ;H:X pointing at first struct
; aix to update pointer into table of 5-byte structures
aix
#5
;point to next 5-byte struct
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Freescale Semiconductor
103
Central Processor Unit (CPU)
The SUB instructions subtract a memory operand from the value in A and store the result in A. The carry
status bit acts as a borrow indicator for this subtraction. SBC subtracts a memory operand and the carry
bit from a previous operation from the value in A and stores the result back in A. This operation allows
performance of multibyte subtractions as demonstrated by the following example.
; 16-bit subtract... result16 = oprE - oprF
lda
oprE+1
;low half of oprE
sub
oprF+1
;oprE(lo) - oprF(lo)
sta
result16+1
;low half of result
lda
oprE
;high half of oprE
sbc
oprF
;oprE(hi) - oprF(hi) - borrow
sta
result16
;high half of result
MUL multiplies the unsigned 8-bit value in X by the unsigned 8-bit value in A and stores the 16-bit result
in X:A where the upper eight bits of the result are stored in X and the lower eight bits of the result are in
A. There is no possibility of a carry (or overflow) since the result will always fit into X:A, so C is cleared
after this operation.
DIV divides the 16-bit unsigned value in H:A by the 8-bit unsigned value in X and stores the 8-bit result in
A and the 8-bit remainder in H. The divisor in X is left unchanged so it could be used in later calculations.
Z indicates whether the result was zero, and C indicates whether there was an attempt to divide by zero
or if there was an overflow. An overflow will occur if the result was greater than 255.
This first divide example shows a simple 8-bit by 8-bit integer divide to get an 8-bit result.
; divide examples
; 8/8 integer divide... A = A/X
clrh
lda
divid8
ldx
divisor
div
sta
quotient8
;clear MS byte of dividend
;load 8-bit dividend
;load divisor
;H:A/X -> A, remainder -> H
;save result
The second divide example demonstrates how to use DIV to perform an 8-bit by 8-bit divide and another
DIV to resolve the remainder into a fractional result (eight more places to the right of the radix point).
; 8/8 integer divide, resolve remainder to 8 fractional bits...
; r8.f8 = A/X, remainder resolved into 8-bit binary fraction
; 16-bit result -> (8-bit integer result).(8-bit fraction)
clrh
;clear MS byte of dividend
lda
divid8
;load 8-bit dividend
ldx
divisor
;load divisor
div
;H:A/X -> A, remainder -> H
sta
quotient16
;upper integer part of result
clra
;H:A = remainder:0
div
;H:A/X -> A
sta
quotient16+1 ;lower fractional part
HCS08 Family Reference Manual, Rev. 2
104
Freescale Semiconductor
Instruction Set Description by Instruction Types
In the third divide example, we divide an 8-bit dividend by a larger 8-bit divisor to get a 16-bit fractional
result where the radix point is just left of the MSB of the result. In a binary fraction, the MSB has a weight
of one-half, the next bit to the right has a weight of one-fourth, and so on.
;
;
;
;
;
8/8 fractional divide, 16-bit fractional result
.r16 = H/X, result is a 16-bit binary fraction
radix assumed to be in same position for H and X
16-bit result -> .(16-bit fraction)
divid8 and divisor defined so H & X both loaded with one ldhx
clra
;clear LS byte of dividend
ldhx
divid8
;H:X = dividend:divisor
div
;H:A/X -> A, remainder -> H
sta
quotient16
;upper byte of result
clra
;H:A = remainder:0
div
;H:A/X -> A
sta
quotient16+1 ;next 8 bits of result
The fourth divide example uses a technique like long division to do an unbounded 16-bit by 8-bit integer
divide.
; unbounded 16/8 integer divide (equivalent to long division)
; r16.f8 = H:A/X, result is 16-bit int.8-bit binary fraction
clrh
;clear MS byte of dividend
lda
divid16
;upper byte of dividend
ldx
divisor
;load divisor
div
;H:A/X -> A, remainder -> H
sta
quotient24
;upper byte of result
lda
divid16+1
;H:A = remainder:dividend(lo)
div
;H:A/X -> A, remainder -> H
sta
quotient24+1 ;next byte of result
clra
;H:A = remainder:0
div
;H:A/X -> A
sta
quotient24+2 ;fractional bits of result
The fifth divide example demonstrates a 16-bit by 8-bit divide with overflow checking.
; bounded 16/8 integer divide (with overflow checking)
; r8 = H:A/X, result is 8-bit integer
ldhx
divid16
;H:X = 16-bit dividend
txa
;H:A = 16-bit dividend
ldx
divisor
;X = 8-bit divisor
div
;H:A/X -> A, remainder -> H
bcs
divOvrflow
;Overflow?
sta
quotient8
;upper byte of result
divOvrflow:
;here on overflow
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
105
Central Processor Unit (CPU)
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-4. Other Arithmetic Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
M ← (M) + $01
A ← (A) + $01
X ← (X) + $01
M ← (M) + $01
M ← (M) + $01
M ← (M) + $01
DIR
INH
INH
IX1
IX
SP1
3C dd
4C
5C
6C ff
7C
9E 6C ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – –
M ← (M) – $01
A ← (A) – $01
X ← (X) – $01
M ← (M) – $01
M ← (M) – $01
M ← (M) – $01
DIR
INH
INH
IX1
IX
SP1
3A dd
4A
5A
6A ff
7A
9E 6A ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – –
DIR
INH
INH
INH
IX1
IX
SP1
3F dd
4F
5F
8C
6F ff
7F
9E 6F ff
5
1
1
1
5
4
6
rfwpp
p
p
p
rfwpp
rfwp
prfwpp
0 1 1 – – 0 1 –
Negate
M ← – (M) = $00 – (M)
(Two’s Complement) A ← – (A) = $00 – (A)
X ← – (X) = $00 – (X)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
DIR
INH
INH
IX1
IX
SP1
30 dd
40
50
60 ff
70
9E 60 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – #opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Compare Accumulator with Memory
A–M
(CCR Updated But Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A1
B1
C1
D1
E1
F1
9E D1
9E E1
ii
dd
hh ll
ee ff
ff
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – ee ff
ff
2
3
4
4
3
3
5
4
CPHX opr16a
CPHX #opr16i
CPHX opr8a
CPHX oprx8,SP
Compare Index Register (H:X) with Memory
(H:X) – (M:M + $0001)
(CCR Updated But Operands Not Changed)
EXT
IMM
DIR
SP1
3E
65
75
9E F3
hh ll
jj kk
dd
ff
6
3
5
6
prrfpp
ppp
rrfpp
prrfpp
1 1 – – CPX
CPX
CPX
CPX
CPX
CPX
CPX
CPX
IMM
DIR
EXT
Compare X (Index Register Low) with Memory
IX2
X–M
IX1
(CCR Updated But Operands Not Changed)
IX
SP2
SP1
A3
B3
C3
D3
E3
F3
9E D3
9E E3
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – INC opr8a
INCA
INCX
INC oprx8,X
INC ,X
INC oprx8,SP
Increment
DEC opr8a
DECA
DECX
DEC oprx8,X
DEC ,X
DEC oprx8,SP
Decrement
CLR opr8a
CLRA
CLRX
CLRH
CLR oprx8,X
CLR ,X
CLR oprx8,SP
Clear
NEG opr8a
NEGA
NEGX
NEG oprx8,X
NEG ,X
NEG oprx8,SP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
TST opr8a
TSTA
TSTX
TST oprx8,X
TST ,X
TST oprx8,SP
DAA
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
Test for Negative or Zero
(M) – $00
(A) – $00
(X) – $00
(M) – $00
(M) – $00
(M) – $00
Decimal Adjust Accumulator
After ADD or ADC of BCD Values
ee ff
ff
DIR
INH
INH
IX1
IX
SP1
3D dd
4D
5D
6D ff
7D
9E 6D ff
4
1
1
4
3
5
rfpp
p
p
rfpp
rfp
prfpp
0 1 1 – – –
INH
72
1
p
U 1 1 – – HCS08 Family Reference Manual, Rev. 2
106
Freescale Semiconductor
Instruction Set Description by Instruction Types
6.5.2.2 Increment, Decrement, Clear, and Negate
Increment and decrement instructions let you adjust the value in A, X, or a memory location by one. Clear
instructions let you force an 8-bit value in A, X, H, or a memory location to zero.
Negate instructions perform a two’s complement operation that is equivalent to multiplying a signed 8-bit
value by negative one. Functionally, this instruction inverts all the bits in A, X, or the memory location and
then adds one. The value $80 represents the signed number –128. The negative of this value would be
+128, but the largest positive number that can be represented with a two’s complement, 8-bit number is
+127. If A was $80 and you execute a NEGA instruction, the CPU first inverts all the bits to get $7F and
then adds one to get $80. Since this causes the sign to change from positive to negative, the V bit in the
CCR is set to indicate the error.
6.5.2.3 Compare and Test
CMP instructions affect CCR bits exactly like the corresponding SUB instruction, but the result is not
stored back into the accumulator so A and the memory operand are left unchanged. Compare instructions
compare the contents of A, X, or the H:X register pair to a memory operand. In the case of CPHX, M is
the address of the referenced memory location, H corresponds to memory location M, and X corresponds
to memory location M+1. CPHX performs a 16-bit subtraction (without storing the result back to H:X).
The test instructions are equivalent to subtracting zero from A, X, or a memory operand. This operation
clears V and sets or clears N and Z according to what was in the tested value. The tested value is not
changed.
6.5.2.4 BCD Arithmetic
In a binary coded decimal (BCD) number, one hexadecimal digit (4 binary bits) represents a single
decimal number from 0 to 9. When two 8-bit BDC numbers are added, the CPU actually does a normal
binary addition. Depending on the BCD values involved, this could result in a value that is no longer a
valid 2-digit BCD number. Based on the H and C condition code bits that resulted from an ADD or ADC
instruction involving two legal BCD numbers, the decimal adjust A (DAA) instruction “corrects” the result
to the proper BCD result and sets or clears the C bit as needed to reflect the result of the BCD addition.
In the past, this was done with a relatively complex set of instructions that tested the values of each BCD
digit of the result and the H and C bits. The DAA instruction greatly simplifies this operation.
The following examples demonstrate two of the possible cases that can result from adding 8-bit BDC
numbers and the actions taken by a DAA instruction to correct the results to the appropriate BCD result
and carry flag. The first example shows a BCD addition that does not require adjustment. The second
example shows a case where the result was not a legal BCD value and the carry did not reflect the correct
BCD result. In this second example, the DAA instruction adds a correction factor and adjusts the carry
flag to reflect the correct BCD result.
lda
add
daa
#$11
#$22
;BCD 11
;11 + 22 = 33
;no adjustment in this case
LDA
#$59
;BCD 59
ADD
#$57
;59 + 57 = $B0
; C=0, H=1, A=$B0 - wanted 59 + 57 = 116 or A=$16 with carry set
DAA
;adds $66 and sets carry
; $B0 + $66 = $16 with carry bit set
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
107
Central Processor Unit (CPU)
6.5.3 Logical Operation Instructions
These instructions perform eight bitwise Boolean operations in parallel. For the complement instruction,
each bit of the register or memory operand is inverted. The other logical instructions involve two operands,
one in the accumulator (A) and the other in memory. Immediate, direct, extended, or indexed (relative to
H:X or SP) addressing modes may be used to access the memory operand. Each bit of the accumulator
is ANDed, ORed, or exclusive-ORed with the corresponding bit of the memory operand. The result of the
logical operation is stored into the accumulator, overwriting the original operand.
AND
AND
AND
AND
AND
AND
AND
AND
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ORA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
EOR
EOR
EOR
EOR
EOR
EOR
EOR
EOR
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
COM opr8a
COMA
COMX
COM oprx8,X
COM ,X
COM oprx8,SP
BIT
BIT
BIT
BIT
BIT
BIT
BIT
BIT
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Object Code
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A4
B4
C4
D4
E4
F4
9E D4
9E E4
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AA
BA
CA
DA
EA
FA
9E DA
9E EA
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A8
B8
C8
D8
E8
F8
9E D8
9E E8
ii
dd
hh ll
ee ff
ff
Complement
M ← (M)= $FF – (M)
(One’s Complement) A ← (A) = $FF – (A)
X ← (X) = $FF – (X)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
DIR
INH
INH
IX1
IX
SP1
33 dd
43
53
63 ff
73
9E 63 ff
Bit Test
(A) & (M)
(CCR Updated but Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A5
B5
C5
D5
E5
F5
9E D5
9E E5
Logical AND
A ← (A) & (M)
Inclusive OR Accumulator and Memory
A ← (A) | (M)
Exclusive OR Memory with Accumulator
A ← (A ⊕ M)
ee ff
ff
ee ff
ff
ee ff
ff
ii
dd
hh ll
ee ff
ff
ee ff
ff
Cycles
Source
Form
Address
Mode
Table 6-5. Logical Operation Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
0 1 1 – – 1
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
HCS08 Family Reference Manual, Rev. 2
108
Freescale Semiconductor
Instruction Set Description by Instruction Types
6.5.3.1 AND, OR, Exclusive-OR, and Complement
These instructions provide the basic AND, OR, exclusive-OR, and invert functions needed to perform
Boolean logical functions.
lda
#$0C
;bit pattern 00001100
and
#$0A
;bit pattern 00001010
; result is..........$08.......................00001000
lda
#$35
;bit pattern 00110101
and
#$0F
;bit pattern 00001111
; result is..........$05.......................00000101
You may notice some similarity between the AND operation and the BCLR instruction. However, BCLR
can be used only on memory locations $0000–$00FF and can clear only one bit at a time while AND can
clear any combination of bits and may be used with several different addressing modes to identify the
memory operand to be ANDed with A.
lda
#$0C
;bit pattern 00001100
ora
#$0A
;bit pattern 00001010
; result is..........$0E.......................00001110
You may notice some similarity between the ORA operation and the BSET instruction; however, BSET
can be used only on memory locations $0000–$00FF and can set only one bit at a time while ORA can
set any combination of bits and may be used with several different addressing modes to identify the
memory operand to be ORed with A.
Exclusive-OR can be used to toggle bits in an operand. One operand is considered a mask where each
bit that is set in the mask corresponds to a bit value in the other operand that will be toggled (inverted).
The next example reads an I/O port, exclusive-ORs it with an immediate mask value of $03 to toggle the
two least significant bits, and then writes the updated result to the I/O port.
402
403
404
405
406
407
408
C162 A6 0C
C164 A8 0A
lda
#$0C
;bit pattern 00001100
eor
#$0A
;bit pattern 00001010
; result is..........$06.......................00000110
C166 B6 00
C168 A8 03
C16A B7 00
lda
eor
sta
PTAD
#$03
PTAD
;read I/O port A
;inverts 2 LSBs
;update I/O port A
Complement instructions simply invert each bit of the operand. Don’t confuse this with the negate
instruction which performs the arithmetic operation equivalent to multiplication by minus one.
lda
coma
#$C5
;bit pattern 11000101
;result is
00111010
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
109
Central Processor Unit (CPU)
6.5.3.2 BIT Instruction
The BIT instruction ANDs each bit of A with the corresponding bit of the addressed memory operand (just
like AND), but the result is not stored to the accumulator. The N and Z condition codes are set or cleared
according to the results of the AND operation to allow conditional branches after the BIT instruction. If you
load A with a mask value where each bit that is set in the mask corresponds to a bit in the memory
operand to be tested, then execute a BIT instruction, the Z bit will be set if none of the tested bits were 1s.
lda
SCI1S1
;read SCI status register
bit
#(mOR+mNF+mFE+mPF) ;mask of all error flags
bne
sciError
;branch if any flags set
; A still contains undisturbed status register
sciError:
;here if any error flags
6.5.4 Shift and Rotate Instructions
All of the shift and rotate instructions operate on a 9-bit field consisting of an 8-bit value in A, X, or a
memory location and the C bit in the CCR. Drawings are provided in the instruction descriptions to show
where the C bit fits into the shift or rotate operation. The logical shift instructions are simple shifts which
shift a zero into the first bit of the value and shift the last bit into the carry bit. The arithmetic shifts treat
the value to be shifted as a signed two’s complement number. An arithmetic shift left is like multiplying a
value by 2 and an arithmetic shift right is like dividing the number by 2. The arithmetic shift right (ASR)
instruction copies the original most significant bit (MSB) back into the MSB to preserve the sign of the
operand. ASL and LSL are just two different mnemonics for the same instruction because there is no
functional difference between the logical and arithmetic shifts to the left.
LSL opr8a
LSLA
LSLX
LSL oprx8,X
LSL ,X
LSL oprx8,SP
LSR opr8a
LSRA
LSRX
LSR oprx8,X
LSR ,X
LSR oprx8,SP
ASL opr8a
ASLA
ASLX
ASL oprx8,X
ASL ,X
ASL oprx8,SP
Operation
Logical Shift Left
C
0
b7
b0
(Same as ASL)
Logical Shift Right
0
C
b7
b0
Arithmetic Shift Left
C
0
b7
(Same as LSL)
b0
Object Code
Cycles
Source
Form
Address
Mode
Table 6-6. Shift and Rotate Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
DIR
INH
INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E 68 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – DIR
INH
INH
IX1
IX
SP1
34 dd
44
54
64 ff
74
9E 64 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – 0 DIR
INH
INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E 68 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – HCS08 Family Reference Manual, Rev. 2
110
Freescale Semiconductor
Instruction Set Description by Instruction Types
ASR opr8a
ASRA
ASRX
ASR oprx8,X
ASR ,X
ASR oprx8,SP
Operation
Arithmetic Shift Right
C
b7
b0
ROL opr8a
ROLA
ROLX
ROL oprx8,X
ROL ,X
ROL oprx8,SP
Rotate Left through Carry
ROR opr8a
RORA
RORX
ROR oprx8,X
ROR ,X
ROR oprx8,SP
Rotate Right through Carry
C
b7
b0
C
b7
b0
Object Code
Cycles
Source
Form
Address
Mode
Table 6-6. Shift and Rotate Instructions (Continued)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
DIR
INH
INH
IX1
IX
SP1
37 dd
47
57
67 ff
77
9E 67 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – DIR
INH
INH
IX1
IX
SP1
39 dd
49
59
69 ff
79
9E 69 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – DIR
INH
INH
IX1
IX
SP1
36 dd
46
56
66 ff
76
9E 66 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – Including the carry bit in the shifts and rotates allows extension of these operations to multibyte values.
The following examples show a 24-bit value being shifted either right or left.
; 24-bit left shift
clc
;clear C bit
; initial condition sum24 = hhhh hhhh : mmmm mmmm : llll llll : 0
lsl
sum24+2
;C to LSB of low byte
; now sum24 = hhhh hhhh : mmmm mmmm : C=l(7) : llll lll0
rol
sum24+1
;rotate middle byte
; now sum24 = hhhh hhhh : C=m(7) : mmmm mmml : llll lll0
rol
sum24
;rotate high byte
; now sum24 = C=h(7) : hhhh hhhm : mmmm mmml : llll lll0
; 24-bit right shift
clc
;clear C bit
; initial condition sum24 = 0 : hhhh hhhh : mmmm mmmm : llll llll
lsr
sum24
;C to MSB of high byte
; now sum24 = 0hhh hhhh : C=h(0) : mmmm mmmm : llll llll
rol
sum24+1
;rotate middle byte
; now sum24 = 0hhh hhhh : hmmm mmmm : C=m(0) : llll lll0
rol
sum24+2
;rotate low byte
; now sum24 = 0hhh hhhm : hmmm mmmm : mlll llll : C=l(0)
Figure 6-5. Multibyte Shifts
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
111
Central Processor Unit (CPU)
6.5.5 Jump, Branch, and Loop Control Instructions
The instructions in this group cause a change of flow which means that the CPU loads a new address into
the program counter so program execution continues at a location other than the next memory location
after the current instruction.
Jump instructions cause an unconditional change in the execution sequence to a new location in a
program. Branch and loop control instructions cause a conditional change in the execution sequence.
Branch and loop control instructions use relative addressing mode to conditionally branch to a location
that is relative to the location of the branch. Processor status indicators in the CCR control whether a
conditional branch or loop control instruction will branch to a new address or simply continue to the next
instruction in the program. BRA is a special case because the branch always occurs and BRN is special
because the branch is never taken (this is functionally equivalent to a 2-byte, 3-cycle NOP). BIL and BIH
are special because they use the state of the IRQ pin rather than the condition of a bit(s) in the CCR to
decide whether to branch.
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-7. Jump and Branch Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
3
4
4
3
3
ppp
pppp
pppp
ppp
ppp
– 1 1 – – – – –
20 rr
3
ppp
– 1 1 – – – – –
REL
21 rr
3
ppp
– 1 1 – – – – –
Branch if Equal (if Z = 1)
REL
27 rr
3
ppp
– 1 1 – – – – –
BNE rel
Branch if Not Equal (if Z = 0)
REL
26 rr
3
ppp
– 1 1 – – – – –
BCC rel
Branch if Carry Bit Clear
(if C = 0)
REL
24 rr
3
ppp
– 1 1 – – – – –
BCS rel
Branch if Carry Bit Set (if C = 1)
(Same as BLO)
REL
25 rr
3
ppp
– 1 1 – – – – –
BPL rel
Branch if Plus (if N = 0)
REL
2A rr
3
ppp
– 1 1 – – – – –
BMI rel
Branch if Minus (if N = 1)
REL
2B rr
3
ppp
– 1 1 – – – – –
BIL rel
Branch if IRQ Pin Low (if IRQ pin = 0)
REL
2E rr
3
ppp
– 1 1 – – – – –
BIH rel
Branch if IRQ Pin High (if IRQ pin = 1)
REL
2F rr
3
ppp
– 1 1 – – – – –
BMC rel
Branch if Interrupt Mask Clear (if I = 0)
REL
2C rr
3
ppp
– 1 1 – – – – –
BMS rel
Branch if Interrupt Mask Set (if I = 1)
REL
2D rr
3
ppp
– 1 1 – – – – –
BHCC rel
Branch if Half Carry Bit Clear (if H = 0)
REL
28 rr
3
ppp
– 1 1 – – – – –
BHCS rel
Branch if Half Carry Bit Set (if H = 1)
REL
29 rr
3
ppp
– 1 1 – – – – –
BLT rel
Branch if Less Than (if N ⊕ V = 1) (Signed)
REL
91 rr
3
ppp
– 1 1 – – – – –
BLE rel
Branch if Less Than or Equal To
(if Z | (N ⊕ V) = 1) (Signed)
REL
93 rr
3
ppp
– 1 1 – – – – –
BGE rel
Branch if Greater Than or Equal To
(if N ⊕ V = 0) (Signed)
REL
90 rr
3
ppp
– 1 1 – – – – –
Jump
PC ← Jump Address
DIR
EXT
IX2
IX1
IX
BC
CC
DC
EC
FC
BRA rel
Branch Always (if I = 1)
REL
BRN rel
Branch Never (if I = 0)
BEQ rel
JMP
JMP
JMP
JMP
JMP
opr8a
opr16a
oprx16,X
oprx8,X
,X
dd
hh ll
ee ff
ff
HCS08 Family Reference Manual, Rev. 2
112
Freescale Semiconductor
Instruction Set Description by Instruction Types
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-7. Jump and Branch Instructions (Continued)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
BGT rel
Branch if Greater Than (if Z | (N ⊕ V) = 0)
(Signed)
REL
92 rr
3
ppp
– 1 1 – – – – –
BLO rel
Branch if Lower (if C = 1) (Same as BCS)
REL
25 rr
3
ppp
– 1 1 – – – – –
BLS rel
Branch if Lower or Same (if C | Z = 1)
REL
23 rr
3
ppp
– 1 1 – – – – –
BHS rel
Branch if Higher or Same (if C = 0)
(Same as BCC)
REL
24 rr
3
ppp
– 1 1 – – – – –
BHI rel
Branch if Higher (if C | Z = 0)
REL
22 rr
3
ppp
– 1 1 – – – – –
6.5.5.1 Unconditional Jump and Branch
Jump (JMP), branch always (BRA), and branch never (BRN) are unconditional and do not depend on the
state of any CCR bits. Jump may be used to go to any memory location in the 64-Kbyte address space
while branch instructions are limited to destinations within –128 to +127 locations from the address
immediately after the branch offset byte.
The following example illustrates the use of a JMP instruction to extend the range of a conditional branch.
For every conditional branch instruction there is another branch that uses the opposite condition. For
example the opposite of a branch if equal (BEQ) instruction is the branch if not equal (BNE) instruction.
Suppose you wrote the instruction:
;
beq
farAway
;more than 128 locs away
and the assembler flagged an error because farAway was more than 128 locations away. You can replace
the BEQ with a BNE that branches around a jump instruction like this:
bne
jmp
aroundJ
farAway
;skip if NOT equal
;jump if equal
;here if not equal
aroundJ:
6.5.5.2 Simple Branches
The simple branches only depend on the state of a single condition (a CCR bit or the IRQ pin state).
Table 6-8. Simple Branch Summary
Branch Condition
Branch if True
Branch if False
Z
BEQ
BNE
C
BCS
BCC
N
BMI
BPL
IRQ pin
BIH
BIL
I
BMS
BMC
H
BHCS
BHCC
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6.5.5.3 Signed Branches
Branch if less than (BLT), branch if less than or equal (BLE), branch if greater than or equal (BGE), and
branch if greater than (BGT) are used after operations involving signed numbers. The simple branches,
branch if equal (BEQ), and branch if not equal (BNE) can also be used after operations involving signed
numbers.
The M68HC05 Family did not implement the V bit in the CCR, so it could not do signed branches. The
difference between signed and unsigned branches is that the signed branches use the exclusive-OR of
N and V in place of the C bit which is used in the Boolean equations that control the unsigned branches.
The exclusive-OR of N and V provides an indication of overflow above +127 (+32,767) or borrow below
–128 (–32,768). The C bit indicates overflow beyond +255 (+65,535).
6.5.5.4 Unsigned Branches
Branch if lower (BLO), branch if lower or same (BLS), branch if higher or same (BHS), and branch if higher
(BHI) are used after operations involving unsigned numbers. The simple branches, branch if equal (BEQ)
and branch if not equal (BNE), can also be used after operations involving unsigned numbers.
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-9. Bit Branches and Loop Conrol
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
Branch if Bit n in Memory Clear (if (Mn) = 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
dd
dd
dd
dd
dd
dd
dd
dd
rr
rr
rr
rr
rr
rr
rr
rr
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– 1 1 – – – – BRSET n,opr8a,rel
Branch if Bit n in Memory Set (if (Mn) = 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
dd
dd
dd
dd
dd
dd
dd
dd
rr
rr
rr
rr
rr
rr
rr
rr
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– 1 1 – – – – CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
Compare and...
DIR
IMM
IMM
IX1+
IX+
SP1
31
41
51
61
71
9E 61
dd
ii
ii
ff
rr
ff
rr
rr
rr
rr
rpppp
pppp
pppp
rpppp
rfppp
prpppp
– 1 1 – – – – –
rr
5
4
4
5
5
6
DBNZ opr8a,rel
DBNZA rel
DBNZX rel
DBNZ oprx8,X,rel
DBNZ ,X,rel
DBNZ oprx8,SP,rel
DIR
INH
Decrement A, X, or M and Branch if Not Zero
INH
(if (result) ≠ 0)
IX1
DBNZX Affects X Not H
IX
SP1
3B
4B
5B
6B
7B
9E 6B
dd rr
rr
rr
ff rr
rr
ff rr
7
4
4
7
6
8
rfwpppp
fppp
fppp
rfwpppp
rfwppp
prfwpppp
– 1 1 – – – – –
BRCLR n,opr8a,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)
6.5.5.5 Bit Condition Branches
These branch instructions test a single bit in a memory operand in direct addressing space
($0000–$00FF) and BRSET branches if the tested bit is set while BRCLR branches if the bit was clear.
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Although this seems like a limited number of locations, it includes all of the I/O and control register space
and a significant portion of the RAM where program variables may be located. By having separate
opcodes for each bit position, these instructions are particularly efficient, requiring only three bytes of
object code and five bus cycles.
waitRDRF:
brclr
RDRF,SCI1S1,waitRDRF ;loop till RDRF set
updateTime:
brclr
bclr
OneSecond,flags,skipUpdate
OneSecond,flags ;acknowledge one sec flag
skipUpdate:
6.5.5.6 Loop Control
The CBEQ instructions compare the contents of the accumulator to a memory location and branch if they
are equal to each other. CBEQA and CBEQX allow A or X to be compared against an immediate operand.
The H:X-relative indexed versions of CBEQ automatically increment H:X after comparing A to the indexed
memory location. These variations can be used to check through a list of values in memory looking for a
particular value such as a null at the end of a string, a carriage return, or an end-of-file mark. The other
variations of CBEQ allow a memory location to be used as a loop counter. (The incrementing or
decrementing of this loop count would be performed by other instructions in the loop.)
lda
#$0D
;ASCII <cr>
cbeq
oprA,gotCR
;skip if oprA=$0D
; here if oprA is anything but <cr>
gotCR:
;here if oprA was <cr>
; similar but IMM addr mode instead of DIR
lda
SCI1DRL
;read SCI character
cbeqa #$0D,gotCR
;branch if it was <cr>
Other examples showing the CBEQ instruction can be found in 6.3.6.2 Indexed, No Offset with Post
Increment (IX+) and 6.3.6.5 Indexed, 16-Bit Offset (IX2).
The DBNZ instructions decrement A, X, or a memory location and then branch if the decremented value
is still not zero. This provides an efficient way to implement a loop counter.
lda
sta
loopTop:
nop
dbnz
#4
directByte
;loop count
;save in RAM
;start of program loop
directByte,loopTop ;loop directByte times
; use local on stack for loop count
lda
#4
;loop count
psha
;put loop count on stack
loopTop1:
nop
dbnz
;start of program loop
1,sp,loopTop1 ;loop directByte times
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Central Processor Unit (CPU)
6.5.6 Stack-Related Instructions
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-10. Stack-Related Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
RSP
Reset Stack Pointer (Low Byte)
SPL ← $FF
(High Byte Not Affected)
INH
9C
1
p
– 1 1 – – – – –
TXS
Transfer Index Reg. to SP
SP ← (H:X) – $0001
INH
94
2
fp
– 1 1 – – – – –
TSX
Transfer SP to Index Reg.
H:X ← (SP) + $0001
INH
95
2
fp
– 1 1 – – – – –
Jump to Subroutine
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
PC ← Unconditional Address
DIR
EXT
IX2
IX1
IX
BD
CD
DD
ED
FD
5
6
6
5
5
ssppp
pssppp
pssppp
ssppp
ssppp
– 1 1 – – – – –
BSR rel
Branch to Subroutine
PC ← (PC) + $0002
push (PCL); SP ← (SP) – $0001
push (PCH); SP ← (SP) – $0001
PC ← (PC) + rel
REL
AD rr
5
ssppp
– 1 1 – – – – –
RTS
Return from Subroutine
SP ← SP + $0001; Pull (PCH)
SP ← SP + $0001; Pull (PCL)
INH
81
5
ufppp
– 1 1 – – – – –
SWI
Software Interrupt
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
INH
83
11
sssssvvfppp
– 1 1 – 1 – – –
RTI
Return from Interrupt
SP ← (SP) + $0001;
SP ← (SP) + $0001;
SP ← (SP) + $0001;
SP ← (SP) + $0001;
SP ← (SP) + $0001;
INH
80
9
uuuuufppp
1 1 PSHA
Push Accumulator onto Stack
Push (A); SP ← (SP) – $0001
INH
87
2
sp
– 1 1 – – – – –
PSHH
Push H (Index Register High) onto Stack
Push (H); SP ← (SP) – $0001
INH
8B
2
sp
– 1 1 – – – – –
PSHX
Push X (Index Register Low) onto Stack
Push (X); SP ← (SP) – $0001
INH
89
2
sp
– 1 1 – – – – –
PULA
Pull Accumulator from Stack
SP ← (SP + $0001); Pull (A)
INH
86
3
ufp
– 1 1 – – – – –
PULH
Pull H (Index Register High) from Stack
SP ← (SP + $0001); Pull (H)
INH
8A
3
ufp
– 1 1 – – – – –
PULX
Pull X (Index Register Low) from Stack
SP ← (SP + $0001); Pull (X)
INH
88
3
ufp
– 1 1 – – – – –
JSR
JSR
JSR
JSR
JSR
opr8a
opr16a
oprx16,X
oprx8,X
,X
Pull (CCR)
Pull (A)
Pull (X)
Pull (PCH)
Pull (PCL)
dd
hh ll
ee ff
ff
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Instruction Set Description by Instruction Types
AIS #opr8i
Operation
Add Immediate Value (Signed) to
Stack Pointer
SP ← (SP) + (M)
IMM
Object Code
A7 ii
Cycles
Source
Form
Address
Mode
Table 6-10. Stack-Related Instructions (Continued)
2
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
pp
– 1 1 – – – – –
The reset stack pointer (RSP) instruction was included for compatibility with the earlier M6805. This
instruction loads the low-order half of SP with $FF and does not affect the high-order half of SP. In the
older architectures, the high half of SP was hard-wired to $00 so RSP would force SP to its reset state
($00FF). In HCS08 systems, $00FF would rarely be used as the starting point of the stack. Also, you
cannot be sure the upper half would remain $00, so RSP is not usually useful in new HCS08 programs.
Transfer H:X to SP (TXS) is most commonly used to set up the initial SP value during reset initialization.
Since SP points one location below where the last actual value is located on the stack, the value in H:X
is decremented by one during the TXS transfer from H:X to SP. The following two instructions may be
used to set SP to point to the last location in RAM which is the normal location for the stack in HCS08
systems.
ldhx
txs
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
Transfer SP to H:X (TSX) is typically used to copy the SP value into H:X so subsequent instructions can
access variables on the stack with H:X-relative indexed addressing instructions which are slightly more
efficient than SP-relative indexed instructions. Because SP points at the next available location on the
stack, the value is automatically incremented by one during the transfer so H:X points at the most recently
stacked byte of information on the stack after the TSX transfer.
Jump-to-subroutine (JSR) and branch-to-subroutine (BSR) instructions are used to go to a sequence of
instructions (a subroutine) somewhere else in a program. Normally, at the end of the subroutine, a
return-from-subroutine (RTS) instruction causes the CPU to return to the next instruction after the JSR or
BSR that called the subroutine.
The software interrupt (SWI) instruction is similar to a JSR except that the X, A, and CCR registers are
saved on the stack in addition to the return PC address, and, rather than specifying a subroutine address
as part of the instruction, the interrupt service routine address is fetched from an interrupt vector near the
end of memory. In the case of SWI, the vector is located at $FFFC and $FFFD.
The more detailed sequence of events for the SWI is:
1. PC is advanced to the next location after the SWI opcode (this is the return address.)
2. Push PCL — Store PC (low byte) at location pointed to by SP and then decrement SP.
3. Push PCH.
4. Push X, A, and CCR in that order — At the end of this sequence the SP points at the next address
below where the CCR was pushed.
5. Set I bit in CCR so interrupts are disabled while executing the interrupt service routine.
6. Load PCH from $FFFC — Fetch high byte of the address for the interrupt service routine.
7. Load PCL from $FFFD.
8. Go to the address that was fetched from $FFFC:FFFD.
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Central Processor Unit (CPU)
For compatibility with the earlier M68HC05, the H register is not automatically stacked. It is good practice
to manually push H at the beginning of the interrupt service routine and to pull H just before returning from
the interrupt service routine.
Other hardware interrupts cause the CPU to execute the same sequence of micro-instructions as the SWI
except that each hardware interrupt source has a different interrupt vector which holds the address of the
interrupt service routine.
Normally, the last instruction in an interrupt service routine is a return from interrupt (RTI). RTI restores
the CCR, A, X, PCH, and PCL in the opposite order that they were saved on the stack. As each byte is
pulled from the stack, SP is incremented by one to point at the data to be pulled and the appropriate
register is loaded from the address pointed to by SP. After executing RTI, the program resumes at the
return address that was just pulled off the stack during the RTI.
The interrupt mask (I bit in the CCR) is set during entry to the interrupt just after the CCR is stacked.
During the RTI, the pre-interrupt value of the CCR is restored which typically restores the I bit to 0 to allow
new interrupts.
Push A (PSHA), push X (PSHX), and push H (PSHH) allow individual CPU registers to be saved on the
stack. The push operation stores the selected register in memory where SP is pointing and then
decrements SP so it points at the next available location on the stack. Pull A, X, and H (PULA, PULX, and
PULH) allow A, X, or H to be loaded with data from the stack. The pull operation first increments SP and
then loads the selected register with the contents of the memory location pointed to by SP.
The following example shows one use of pushes and pulls. Some C compilers use X:A to pass a 16-bit
parameter to a function. This code segment shows how this integer value is saved on the stack (lines 604
and 605) and then later gets loaded into H:X (line 620) where it can be used as an index pointer. Notice
that you can push one register (line 605) and then pull that value into a different register. (Nothing about
the value on the stack associates it with a particular CPU register.)
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
C1F2 87
C1F3 89
C1F4 A7 FD
C1F6
C1F9
C1FC
C1FE
C201
C204
C205
C207
C208
9E6F 02
9E6F 03
A6 04
9EE7 01
45 00A0
F6
AF 01
89
8B
*********************
* multAcc - 4 iteration mutiply-accumulate example
*********************
; 9 stack bytes used for this routine including return addr
; a pointer is passed in X:A, 3 bytes are used for stack locals,
; and two bytes are used for temporary storage on stack
; pntr points at list of 4 constant multipliers k(0) - k(3)
; VarY is a 16-bit integer, VarN is an 8-bit loop count
; VarY = sum( k(0)*oprA + k(1)*oprB + k(2)*oprC + k(3)*oprD)
; return result (VarY) in X:A
multAcc:
psha
;save pntr LS byte
pshx
;save pntr MS byte
ais
#-3
;allocate for 3 local bytes
; at this point VarN @ 1,sp; VarY(hi) @ 2,sp; VarY(lo) @ 3,sp;
; pntr(hi) @ 4,sp; pntr(lo) @ 5,sp
clr
2,sp
;VarY MS byte on stack
clr
3,sp
;VarY LS byte on stack
lda
#4
;loop count
sta
1,sp
;VarN = 4
ldhx
#oprA
;operands oprA-oprD
iteration:
lda
,x
;get operand(n)
aix
#1
;point to next operand
pshx
;MS byte of oprX pointer
pshh
;LS byte of oprX pointer
; at this point VarN @ 3,sp; VarY(hi) @ 4,sp; VarY(lo) @ 5,sp;
; pntr(hi) @ 6,sp; pntr(lo) @ 7,sp
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Instruction Set Description by Instruction Types
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
C209
C20C
C20F
C211
C214
C215
C216
C219
C21C
C21D
C21E
9EFE 06
9E6C 07
26 03
9E6C 06
FE
42
9EEB 05
9EE7 05
9F
8A
88
C21F
C222
C225
C229
C22C
C22F
C231
9EE9 02
9EE7 02
9E6B 01
9EEE 02
9EE6 03
A7 05
81
ldhx
6,sp
;load pntr from stack (6,sp)
inc
7,sp
;pntr(lo)=pntr(lo)+1
bne
skip
;skip if no carry
inc
6,sp
;add carry into pntr(hi)
skip:
ldx
,x
;load k(n)
mul
;A*X -> X:A
add
5,sp
;add to VarY(lo)
sta
5,sp
;update VarY(lo)
txa
;MS byte to A
pulh
;restore oprX pointer (hi)
pulx
;restore oprX pointer (lo)
; at this point VarN @ 1,sp; VarY(hi) @ 2,sp; VarY(lo) @ 3,sp;
; pntr(hi) @ 4,sp; pntr(lo) @ 5,sp
adc
2,sp
;add with carry to VarY(hi)
sta
2,sp
;update VarY(hi)
DB
dbnz
1,sp,iteration ;dec VarN and loop if not 0
ldx
2,sp
;VarY(hi)
lda
3,sp
;VarY(lo)
ais
#5
;deallocate all locals
rts
;return VarY in X:A
*********************
The add immediate to stack pointer (AIS) instruction allows an 8-bit signed immediate value to be added
to SP. This is most commonly used to allocate and deallocate space on the stack for local variables.
Adding a negative number to SP allocates space on the stack and adding a positive number to SP
deallocates space.
ais
ais
#-5
#5
;allocate 5 bytes for locals
;deallocate local space
6.5.7 Miscellaneous Instructions
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-11. Miscellaneous Instructions
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
NOP
No Operation — Uses 1 Bus Cycle
INH
9D
1
p
– 1 1 – – – – –
SEC
Set Carry Bit
(C ← 1)
INH
99
1
p
– 1 1 – – – – 1
CLC
Clear Carry Bit (C ← 0)
INH
98
1
p
– 1 1 – – – – 0
SEI
Set Interrupt Mask Bit
(I ← 1)
INH
9B
1
p
– 1 1 – 1 – – –
CLI
Clear Interrupt Mask Bit (I ← 0)
INH
9A
1
p
– 1 1 – 0 – – –
BGND
Enter active background if ENBDM = 1
Waits for and processes BDM commands until INH
GO, TRACE1, or TAGGO
82
5+
fp...ppp
– 1 1 – – – – –
WAIT
Enable Interrupts; Wait for Interrupt
I bit ← 0; Halt CPU
INH
8F
2+
fp...
– 1 1 – 0 – – –
STOP
Enable Interrupts: Stop Processing
Refer to MCU Documentation
I bit ← 0; Stop Processing
INH
8E
2+
fp...
– 1 1 – 0 – – –
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Central Processor Unit (CPU)
The no-operation (NOP) instruction is typically used in software generated delay programs. It consumes
execution time but does not cause any changes to condition code bits or other CPU registers. This
example uses a software loop including a NOP to generate a 1 ms delay.
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
C232
C233
C234
C235
C238
C23A
C23D
C23F
C240
C241
8B
89
9D
45
AF
65
26
88
8A
81
09C0
FF
0000
F9
*********************
* dly1ms - delay 1ms at bus frequency = 20MHz
*********************
; 1 bus cycle = 50 nanoseconds so 20,000 cycles = 1ms
; JSR (EXT) takes [5 or 6] cycles. Total overhead is 24-25 cycles
; total delay 20000 = 8n+24; so n = 19976/8 = 2497
dly1ms:
pshh
;[2] save H
pshx
;[2] save X
nop
;[1] makes n even
ldhx
#2496
;[3] loop count
loop1ms:
aix
#-1
;[2] H:X = H:X - 1
cphx
#$0000
;[3] check for zero
bne
loop1ms
;[3] loop till H:X = $0000
pulx
;[3] restore X
pulh
;[3] restore H
rts
;[6] return
*********************
One way the set and clear carry (SEC and CLC) instructions can be used is to force the value of the carry
bit before doing a shift or rotate instruction. See Figure 6-5 for more information.
Set interrupt mask (SEI) and clear interrupt mask (CLI) instructions are used to disable or enable
interrupts, respectively. After reset, the I bit is set to prevent interrupts before the stack pointer and other
system conditions have been initialized. After enough system initialization has been completed, use a CLI
instruction to enable interrupts. In some programs, it is necessary to prevent interrupts during some
sensitive code sequence. SEI is used before the sequence and CLI is used after the sequence to prevent
interrupts during the sensitive code sequence.
The background (BGND), WAIT, and STOP instructions are unusual in that they cause the CPU to stop
executing new instructions for an indefinite period of time. A hardware event, such as an interrupt or a
serial background debug command, is needed to tell the CPU when it is time to resume processing normal
instructions. In the instruction detail tables, these instructions are listed with a minimum number of bus
cycles, followed by a + (plus) to indicate that this is the minimum number of cycles needed to complete
these instructions.
BGND instructions can be used by a development system to set software breakpoints in a user program
that is being debugged. Normal user programs never use the BGND instruction. When the CPU
encounters a BGND instruction, it checks the ENBDM control bit in the background debug controller
module. This control bit is not accessible to a user program; it can be changed only by reset or a serial
background command. If ENBDM = 0 (its default state), BGND opcodes are treated as illegal instructions
which cause an MCU reset. For more information about background debug mode, see 7.3 Background
Debug Controller (BDC).
WAIT causes the CPU to shut down its clocks to save power. Other peripheral systems continue to run
normally. An interrupt or reset event is needed to wake up the CPU from wait mode. The interrupt can
come from the external IRQ pin or from an internal peripheral system. See 3.5 Wait Mode for a detailed
discussion of the wait mode.
STOP forces the MCU to turn off all system clocks to reduce system power to an absolute minimum. In
previous M68HC05 and M68HC08 systems, all clocks including the oscillator were disabled in stop mode.
Depending on the version of the clock generation circuitry in an HCS08 system, you can set control bits
so the oscillator and the timebase module continue to operate in stop mode. This provides a means of
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Instruction Set Summary
waking the MCU from stop mode periodically without any external components. All clocks other than the
oscillator and a small number of flip-flops in the timebase module are stopped in this mode, so system
power is reduced to a bare minimum.
The HCS08 always starts out using a self-clocked clock source after reset or stop to avoid delays
associated with crystal startup. After stop, the CPU starts execution by responding to the interrupt or reset
event that woke it up. For more detailed information, refer to 3.6 Stop Modes.
6.6 Instruction Set Summary
Table 6-12 provides a summary of the HCS08 instruction set in all possible addressing modes. The table
shows operand construction, execution time in internal bus clock cycles, and cycle-by-cycle details for
each addressing mode variation of each instruction.
The nomenclature listed following Table 6-12 is used in the instruction descriptions in Table 6-1 through
Table 6-11.
ADC
ADC
ADC
ADC
ADC
ADC
ADC
ADC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ADD
ADD
ADD
ADD
ADD
ADD
ADD
ADD
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Operation
Add with Carry
A ← (A) + (M) + (C)
Add without Carry
A ← (A) + (M)
Object Code
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A9
B9
C9
D9
E9
F9
9E D9
9E E9
ii
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AB
BB
CB
DB
EB
FB
9E DB
9E EB
ii
dd
hh ll
ee ff
ff
ee ff
ff
ee ff
ff
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 1 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – 2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – AIS #opr8i
Add Immediate Value (Signed) to
Stack Pointer
SP ← (SP) + (M)
IMM
A7 ii
2
pp
– 1 1 – – – – –
AIX #opr8i
Add Immediate Value (Signed) to
Index Register (H:X)
H:X ← (H:X) + (M)
IMM
AF ii
2
pp
– 1 1 – – – – –
Logical AND
A ← (A) & (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
AND
AND
AND
AND
AND
AND
AND
AND
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
A4
B4
C4
D4
E4
F4
9E D4
9E E4
ii
dd
hh ll
ee ff
ff
ee ff
ff
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
121
Central Processor Unit (CPU)
Operation
Arithmetic Shift Left
Object Code
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 2 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
DIR
INH
INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E 68 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – DIR
INH
INH
IX1
IX
SP1
37 dd
47
57
67 ff
77
9E 67 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – Branch if Carry Bit Clear
(if C = 0)
REL
24 rr
3
ppp
– 1 1 – – – – –
BCLR n,opr8a
Clear Bit n in Memory
(Mn ← 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– 1 1 – – – – –
BCS rel
Branch if Carry Bit Set (if C = 1)
(Same as BLO)
REL
25 rr
3
ppp
– 1 1 – – – – –
BEQ rel
Branch if Equal (if Z = 1)
REL
27 rr
3
ppp
– 1 1 – – – – –
BGE rel
Branch if Greater Than or Equal To
(if N ⊕ V = 0) (Signed)
REL
90 rr
3
ppp
– 1 1 – – – – –
BGND
Enter active background if ENBDM = 1
Waits for and processes BDM commands until INH
GO, TRACE1, or TAGGO
82
5+
fp...ppp
– 1 1 – – – – –
BGT rel
Branch if Greater Than (if Z | (N ⊕ V) = 0)
(Signed)
REL
92 rr
3
ppp
– 1 1 – – – – –
BHCC rel
Branch if Half Carry Bit Clear (if H = 0)
REL
28 rr
3
ppp
– 1 1 – – – – –
BHCS rel
Branch if Half Carry Bit Set (if H = 1)
REL
29 rr
3
ppp
– 1 1 – – – – –
BHI rel
Branch if Higher (if C | Z = 0)
REL
22 rr
3
ppp
– 1 1 – – – – –
BHS rel
Branch if Higher or Same (if C = 0)
(Same as BCC)
REL
24 rr
3
ppp
– 1 1 – – – – –
BIH rel
Branch if IRQ Pin High (if IRQ pin = 1)
REL
2F rr
3
ppp
– 1 1 – – – – –
BIL rel
Branch if IRQ Pin Low (if IRQ pin = 0)
REL
2E rr
3
ppp
– 1 1 – – – – –
Bit Test
(A) & (M)
(CCR Updated but Operands Not Changed)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
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
BIT
BIT
BIT
BIT
BIT
BIT
BIT
BIT
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
C
0
b7
b0
(Same as LSL)
Arithmetic Shift Right
C
b7
b0
A5
B5
C5
D5
E5
F5
9E D5
9E E5
ii
dd
hh ll
ee ff
ff
ee ff
ff
HCS08 Family Reference Manual, Rev. 2
122
Freescale Semiconductor
Instruction Set Summary
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 3 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
BLE rel
Branch if Less Than or Equal To
(if Z | (N ⊕ V) = 1) (Signed)
REL
93 rr
3
ppp
– 1 1 – – – – –
BLO rel
Branch if Lower (if C = 1) (Same as BCS)
REL
25 rr
3
ppp
– 1 1 – – – – –
BLS rel
Branch if Lower or Same (if C | Z = 1)
REL
23 rr
3
ppp
– 1 1 – – – – –
BLT rel
Branch if Less Than (if N ⊕ V = 1) (Signed)
REL
91 rr
3
ppp
– 1 1 – – – – –
BMC rel
Branch if Interrupt Mask Clear (if I = 0)
REL
2C rr
3
ppp
– 1 1 – – – – –
BMI rel
Branch if Minus (if N = 1)
REL
2B rr
3
ppp
– 1 1 – – – – –
BMS rel
Branch if Interrupt Mask Set (if I = 1)
REL
2D rr
3
ppp
– 1 1 – – – – –
BNE rel
Branch if Not Equal (if Z = 0)
REL
26 rr
3
ppp
– 1 1 – – – – –
BPL rel
Branch if Plus (if N = 0)
REL
2A rr
3
ppp
– 1 1 – – – – –
BRA rel
Branch Always (if I = 1)
REL
20 rr
3
ppp
– 1 1 – – – – –
BRCLR n,opr8a,rel
Branch if Bit n in Memory Clear (if (Mn) = 0)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– 1 1 – – – – BRN rel
Branch Never (if I = 0)
REL
21 rr
3
ppp
– 1 1 – – – – –
Branch if Bit n in Memory Set (if (Mn) = 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
rpppp
– 1 1 – – – – BSET n,opr8a
Set Bit n in Memory (Mn ← 1)
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
5
5
5
5
5
5
5
5
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
rfwpp
– 1 1 – – – – –
BSR rel
Branch to Subroutine
PC ← (PC) + $0002
push (PCL); SP ← (SP) – $0001
push (PCH); SP ← (SP) – $0001
PC ← (PC) + rel
REL
AD rr
5
ssppp
– 1 1 – – – – –
5
4
4
5
5
6
rpppp
pppp
pppp
rpppp
rfppp
prpppp
– 1 1 – – – – –
BRSET n,opr8a,rel
CBEQ opr8a,rel
CBEQA #opr8i,rel
CBEQX #opr8i,rel
CBEQ oprx8,X+,rel
CBEQ ,X+,rel
CBEQ oprx8,SP,rel
Compare and...
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (X) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
Branch if (A) = (M)
DIR
IMM
IMM
IX1+
IX+
SP1
31
41
51
61
71
9E 61
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
rr
rr
rr
rr
rr
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
123
Central Processor Unit (CPU)
Operation
Object Code
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 4 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
CLC
Clear Carry Bit (C ← 0)
INH
98
1
p
– 1 1 – – – – 0
CLI
Clear Interrupt Mask Bit (I ← 0)
INH
9A
1
p
– 1 1 – 0 – – –
CLR opr8a
CLRA
CLRX
CLRH
CLR oprx8,X
CLR ,X
CLR oprx8,SP
Clear
DIR
INH
INH
INH
IX1
IX
SP1
3F dd
4F
5F
8C
6F ff
7F
9E 6F ff
5
1
1
1
5
4
6
rfwpp
p
p
p
rfwpp
rfwp
prfwpp
0 1 1 – – 0 1 –
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A1
B1
C1
D1
E1
F1
9E D1
9E E1
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – 5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
0 1 1 – – 1
CMP
CMP
CMP
CMP
CMP
CMP
CMP
CMP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
M ← $00
A ← $00
X ← $00
H ← $00
M ← $00
M ← $00
M ← $00
Compare Accumulator with Memory
A–M
(CCR Updated But Operands Not Changed)
ii
dd
hh ll
ee ff
ff
ee ff
ff
COM opr8a
COMA
COMX
COM oprx8,X
COM ,X
COM oprx8,SP
Complement
M ← (M)= $FF – (M)
(One’s Complement) A ← (A) = $FF – (A)
X ← (X) = $FF – (X)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
M ← (M) = $FF – (M)
DIR
INH
INH
IX1
IX
SP1
33 dd
43
53
63 ff
73
9E 63 ff
CPHX opr16a
CPHX #opr16i
CPHX opr8a
CPHX oprx8,SP
Compare Index Register (H:X) with Memory
(H:X) – (M:M + $0001)
(CCR Updated But Operands Not Changed)
EXT
IMM
DIR
SP1
3E
65
75
9E F3
hh ll
jj kk
dd
ff
6
3
5
6
prrfpp
ppp
rrfpp
prrfpp
1 1 – – CPX
CPX
CPX
CPX
CPX
CPX
CPX
CPX
IMM
DIR
EXT
Compare X (Index Register Low) with Memory
IX2
X–M
IX1
(CCR Updated But Operands Not Changed)
IX
SP2
SP1
A3
B3
C3
D3
E3
F3
9E D3
9E E3
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – 1
p
U 1 1 – – 7
4
4
7
6
8
rfwpppp
fppp
fppp
rfwpppp
rfwppp
prfwpppp
– 1 1 – – – – –
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – –
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
DAA
Decimal Adjust Accumulator
After ADD or ADC of BCD Values
INH
72
DBNZ opr8a,rel
DBNZA rel
DBNZX rel
DBNZ oprx8,X,rel
DBNZ ,X,rel
DBNZ oprx8,SP,rel
DIR
INH
Decrement A, X, or M and Branch if Not Zero
INH
(if (result) ≠ 0)
IX1
DBNZX Affects X Not H
IX
SP1
3B
4B
5B
6B
7B
9E 6B
DEC opr8a
DECA
DECX
DEC oprx8,X
DEC ,X
DEC oprx8,SP
Decrement
M ← (M) – $01
A ← (A) – $01
X ← (X) – $01
M ← (M) – $01
M ← (M) – $01
M ← (M) – $01
DIR
INH
INH
IX1
IX
SP1
ee ff
ff
dd rr
rr
rr
ff rr
rr
ff rr
3A dd
4A
5A
6A ff
7A
9E 6A ff
HCS08 Family Reference Manual, Rev. 2
124
Freescale Semiconductor
Instruction Set Summary
Divide
A ← (H:A)÷(X); H ← Remainder
DIV
EOR
EOR
EOR
EOR
EOR
EOR
EOR
EOR
Operation
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
INC opr8a
INCA
INCX
INC oprx8,X
INC ,X
INC oprx8,SP
Exclusive OR Memory with Accumulator
A ← (A ⊕ M)
Increment
M ← (M) + $01
A ← (A) + $01
X ← (X) + $01
M ← (M) + $01
M ← (M) + $01
M ← (M) + $01
Object Code
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 5 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
6
fffffp
– 1 1 – – – 2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – –
dd
hh ll
ee ff
ff
3
4
4
3
3
ppp
pppp
pppp
ppp
ppp
– 1 1 – – – – –
INH
52
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A8
B8
C8
D8
E8
F8
9E D8
9E E8
DIR
INH
INH
IX1
IX
SP1
3C dd
4C
5C
6C ff
7C
9E 6C ff
BC
CC
DC
EC
FC
ii
dd
hh ll
ee ff
ff
ee ff
ff
JMP
JMP
JMP
JMP
JMP
opr8a
opr16a
oprx16,X
oprx8,X
,X
Jump
PC ← Jump Address
DIR
EXT
IX2
IX1
IX
JSR
JSR
JSR
JSR
JSR
opr8a
opr16a
oprx16,X
oprx8,X
,X
Jump to Subroutine
PC ← (PC) + n (n = 1, 2, or 3)
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
PC ← Unconditional Address
DIR
EXT
IX2
IX1
IX
BD
CD
DD
ED
FD
dd
hh ll
ee ff
ff
5
6
6
5
5
ssppp
pssppp
pssppp
ssppp
ssppp
– 1 1 – – – – –
LDA
LDA
LDA
LDA
LDA
LDA
LDA
LDA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Load Accumulator from Memory
A ← (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A6
B6
C6
D6
E6
F6
9E D6
9E E6
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
Load Index Register (H:X)
H:X ← (M:M + $0001)
IMM
DIR
EXT
IX
IX2
IX1
SP1
jj kk
dd
hh ll
9E
9E
9E
9E
45
55
32
AE
BE
CE
FE
3
4
5
5
6
5
5
ppp
rrpp
prrpp
prrfp
pprrpp
prrpp
prrpp
0 1 1 – – –
Load X (Index Register Low) from Memory
X ← (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AE
BE
CE
DE
EE
FE
9E DE
9E EE
ii
dd
hh ll
ee ff
ff
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
LDHX
LDHX
LDHX
LDHX
LDHX
LDHX
LDHX
LDX
LDX
LDX
LDX
LDX
LDX
LDX
LDX
#opr16i
opr8a
opr16a
,X
oprx16,X
oprx8,X
oprx8,SP
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
ee ff
ff
ee ff
ff
ff
ee ff
ff
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
125
Central Processor Unit (CPU)
LSL opr8a
LSLA
LSLX
LSL oprx8,X
LSL ,X
LSL oprx8,SP
LSR opr8a
LSRA
LSRX
LSR oprx8,X
LSR ,X
LSR oprx8,SP
Operation
Logical Shift Left
C
0
b7
b0
(Same as ASL)
Logical Shift Right
0
C
b7
b0
Object Code
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 6 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
DIR
INH
INH
IX1
IX
SP1
38 dd
48
58
68 ff
78
9E 68 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – DIR
INH
INH
IX1
IX
SP1
34 dd
44
54
64 ff
74
9E 64 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – 0 5
5
4
5
rpwpp
rfwpp
pwpp
rfwpp
0 1 1 – – –
MOV opr8a,opr8a
MOV opr8a,X+
MOV #opr8i,opr8a
MOV ,X+,opr8a
Move
(M)destination ← (M)source
In IX+/DIR and DIR/IX+ Modes,
H:X ← (H:X) + $0001
DIR/DIR
DIR/IX+
IMM/DIR
IX+/DIR
4E
5E
6E
7E
MUL
Unsigned multiply
X:A ← (X) × (A)
INH
42
5
ffffp
– 1 1 0 – – – 0
NEG opr8a
NEGA
NEGX
NEG oprx8,X
NEG ,X
NEG oprx8,SP
Negate
M ← – (M) = $00 – (M)
(Two’s Complement) A ← – (A) = $00 – (A)
X ← – (X) = $00 – (X)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
M ← – (M) = $00 – (M)
DIR
INH
INH
IX1
IX
SP1
30 dd
40
50
60 ff
70
9E 60 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – NOP
No Operation — Uses 1 Bus Cycle
INH
9D
1
p
– 1 1 – – – – –
NSA
Nibble Swap Accumulator
A ← (A[3:0]:A[7:4])
INH
62
1
p
– 1 1 – – – – –
Inclusive OR Accumulator and Memory
A ← (A) | (M)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
AA
BA
CA
DA
EA
FA
9E DA
9E EA
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
0 1 1 – – –
ORA
ORA
ORA
ORA
ORA
ORA
ORA
ORA
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
dd dd
dd
ii dd
dd
ii
dd
hh ll
ee ff
ff
ee ff
ff
PSHA
Push Accumulator onto Stack
Push (A); SP ← (SP) – $0001
INH
87
2
sp
– 1 1 – – – – –
PSHH
Push H (Index Register High) onto Stack
Push (H); SP ← (SP) – $0001
INH
8B
2
sp
– 1 1 – – – – –
PSHX
Push X (Index Register Low) onto Stack
Push (X); SP ← (SP) – $0001
INH
89
2
sp
– 1 1 – – – – –
PULA
Pull Accumulator from Stack
SP ← (SP + $0001); Pull (A)
INH
86
3
ufp
– 1 1 – – – – –
PULH
Pull H (Index Register High) from Stack
SP ← (SP + $0001); Pull (H)
INH
8A
3
ufp
– 1 1 – – – – –
HCS08 Family Reference Manual, Rev. 2
126
Freescale Semiconductor
Instruction Set Summary
PULX
Operation
Pull X (Index Register Low) from Stack
SP ← (SP + $0001); Pull (X)
ROL opr8a
ROLA
ROLX
ROL oprx8,X
ROL ,X
ROL oprx8,SP
Rotate Left through Carry
ROR opr8a
RORA
RORX
ROR oprx8,X
ROR ,X
ROR oprx8,SP
Rotate Right through Carry
C
b7
b0
C
b7
b0
Object Code
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 7 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
INH
88
3
ufp
– 1 1 – – – – –
DIR
INH
INH
IX1
IX
SP1
39 dd
49
59
69 ff
79
9E 69 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – DIR
INH
INH
IX1
IX
SP1
36 dd
46
56
66 ff
76
9E 66 ff
5
1
1
5
4
6
rfwpp
p
p
rfwpp
rfwp
prfwpp
1 1 – – RSP
Reset Stack Pointer (Low Byte)
SPL ← $FF
(High Byte Not Affected)
INH
9C
1
p
– 1 1 – – – – –
RTI
Return from Interrupt
SP ← (SP) + $0001;
SP ← (SP) + $0001;
SP ← (SP) + $0001;
SP ← (SP) + $0001;
SP ← (SP) + $0001;
INH
80
9
uuuuufppp
1 1 RTS
Return from Subroutine
SP ← SP + $0001; Pull (PCH)
SP ← SP + $0001; Pull (PCL)
INH
81
5
ufppp
– 1 1 – – – – –
Subtract with Carry
A ← (A) – (M) – (C)
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A2
B2
C2
D2
E2
F2
9E D2
9E E2
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – SBC
SBC
SBC
SBC
SBC
SBC
SBC
SBC
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
Pull (CCR)
Pull (A)
Pull (X)
Pull (PCH)
Pull (PCL)
ii
dd
hh ll
ee ff
ff
ee ff
ff
SEC
Set Carry Bit
(C ← 1)
INH
99
1
p
– 1 1 – – – – 1
SEI
Set Interrupt Mask Bit
(I ← 1)
INH
9B
1
p
– 1 1 – 1 – – –
Store Accumulator in Memory
M ← (A)
DIR
EXT
IX2
IX1
IX
SP2
SP1
B7
C7
D7
E7
F7
9E D7
9E E7
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 1 1 – – –
ee ff
ff
3
4
4
3
2
5
4
DIR
EXT
SP1
35 dd
96 hh ll
9E FF ff
4
5
5
wwpp
pwwpp
pwwpp
0 1 1 – – –
STA
STA
STA
STA
STA
STA
STA
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
STHX opr8a
STHX opr16a
STHX oprx8,SP
Store H:X (Index Reg.)
(M:M + $0001) ← (H:X)
dd
hh ll
ee ff
ff
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
127
Central Processor Unit (CPU)
Operation
Object Code
Enable Interrupts: Stop Processing
Refer to MCU Documentation
I bit ← 0; Stop Processing
INH
8E
Store X (Low 8 Bits of Index Register)
in Memory
M ← (X)
DIR
EXT
IX2
IX1
IX
SP2
SP1
BF
CF
DF
EF
FF
9E DF
9E EF
dd
hh ll
ee ff
ff
IMM
DIR
EXT
IX2
IX1
IX
SP2
SP1
A0
B0
C0
D0
E0
F0
9E D0
9E E0
ii
dd
hh ll
ee ff
ff
SWI
Software Interrupt
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
INH
TAP
Transfer Accumulator to CCR
CCR ← (A)
TAX
TPA
STOP
STX
STX
STX
STX
STX
STX
STX
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
SUB
SUB
SUB
SUB
SUB
SUB
SUB
SUB
#opr8i
opr8a
opr16a
oprx16,X
oprx8,X
,X
oprx16,SP
oprx8,SP
TST opr8a
TSTA
TSTX
TST oprx8,X
TST ,X
TST oprx8,SP
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 8 of 9)
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
2+
fp...
– 1 1 – 0 – – –
3
4
4
3
2
5
4
wpp
pwpp
pwpp
wpp
wp
ppwpp
pwpp
0 1 1 – – –
2
3
4
4
3
3
5
4
pp
rpp
prpp
prpp
rpp
rfp
pprpp
prpp
1 1 – – 83
11
sssssvvfppp
– 1 1 – 1 – – –
INH
84
1
p
1 1 Transfer Accumulator to X (Index Register
Low)
X ← (A)
INH
97
1
p
– 1 1 – – – – –
Transfer CCR to Accumulator
A ← (CCR)
INH
85
1
p
– 1 1 – – – – –
DIR
INH
INH
IX1
IX
SP1
3D dd
4D
5D
6D ff
7D
9E 6D ff
4
1
1
4
3
5
rfpp
p
p
rfpp
rfp
prfpp
0 1 1 – – –
Subtract
A ← (A) – (M)
Test for Negative or Zero
(M) – $00
(A) – $00
(X) – $00
(M) – $00
(M) – $00
(M) – $00
ee ff
ff
ee ff
ff
TSX
Transfer SP to Index Reg.
H:X ← (SP) + $0001
INH
95
2
fp
– 1 1 – – – – –
TXA
Transfer X (Index Reg. Low) to Accumulator
A ← (X)
INH
9F
1
p
– 1 1 – – – – –
TXS
Transfer Index Reg. to SP
SP ← (H:X) – $0001
INH
94
2
fp
– 1 1 – – – – –
HCS08 Family Reference Manual, Rev. 2
128
Freescale Semiconductor
Instruction Set Summary
WAIT
Operation
Enable Interrupts; Wait for Interrupt
I bit ← 0; Halt CPU
INH
Object Code
8F
Cycles
Source
Form
Address
Mode
Table 6-12. Instruction Set Summary (Sheet 9 of 9)
2+
Cyc-by-Cyc
Details
Effect
on CCR
V11H INZC
fp...
– 1 1 – 0 – – –
Source Form: Everything in the source form columns, except expressions in italic characters, is literal information which must appear in the
assembly source file exactly as shown. The initial 3- to 5-letter mnemonic and the characters (# , ( ) and +) are always 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 direct-page address ($00xx).
opr16a Any label or expression that evaluates to a 16-bit address.
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, used for indexed addressing.
rel
Any label or expression that refers to an address that is within –128 to +127 locations from the start of the next instruction.
Operation Symbols:
A
Accumulator
CCR Condition code register
H
Index register high byte
M
Memory location
n
Any bit
opr
Operand (one or two bytes)
PC
Program counter
PCH Program counter high byte
PCL Program counter low byte
rel
Relative program counter offset byte
SP
Stack pointer
SPL Stack pointer low byte
X
Index register low byte
&
Logical AND
|
Logical OR
⊕
Logical EXCLUSIVE OR
()
Contents of
+
Add
–
Subtract, Negation (two’s complement)
×
Multiply
÷
Divide
#
Immediate value
←
Loaded with
:
Concatenated with
Addressing Modes:
DIR Direct addressing mode
EXT Extended addressing mode
IMM Immediate addressing mode
INH Inherent addressing mode
IX
Indexed, no offset addressing mode
IX1
Indexed, 8-bit offset addressing mode
IX2
Indexed, 16-bit offset addressing mode
IX+
Indexed, no offset, post increment addressing mode
IX1+ Indexed, 8-bit offset, post increment addressing mode
REL Relative addressing mode
SP1 Stack pointer, 8-bit offset addressing mode
SP2 Stack pointer 16-bit offset addressing mode
CCR Bits:
V
Overflow bit
H
Half-carry bit
I
Interrupt mask
N
Negative bit
Z
Zero bit
C
Carry/borrow bit
CCR Effects:
Set or cleared
–
Not affected
U
Undefined
Cycle-by-Cycle Codes:
f
Free cycle. This indicates a cycle where the CPU
does not require use of the system buses. An f
cycle is always one cycle of the system bus clock
and is always a read cycle.
p
Progryam fetch; read from next consecutive
location in program memory
r
Read 8-bit operand
s
Push (write) one byte onto stack
u
Pop (read) one byte from stack
v
Read vector from $FFxx (high byte first)
w
Write 8-bit operand
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
129
Bit-Manipulation
00
BRSET0
3
01
BSET0
02
5 12
BRSET1
3
DIR 2
03
BCLR1
DIR 2
04
5 14
HCS08 Family Reference Manual, Rev. 2
05
5 25
BCLR2
DIR 2
06
5 16
BRSET3
3
5 26
BSET3
DIR 2
07
5 17
BRCLR3
3
DIR 2
08
BRSET4
3
BSET4
09
5 19
BRCLR4
0A
5 1A
BRSET5
3
DIR 2
0B
0C
5 1C
BRSET6
3
0D
0E
Freescale Semiconductor
DIR 2
0F
5 2E
BSET7
BRCLR7
DIR 2
REL 3
5 2F
BCLR7
DIR 2
BIH
REL 2
5 5E
MOV
EXT 3
3 3F
5 6E
CLRA
DIR 1
INHInherentRELRelativeSP1Stack Pointer, 8-Bit Offset
IMMImmediateIXIndexed, No OffsetSP2Stack Pointer, 16-Bit Offset
DIRDirectIX1Indexed, 8-Bit OffsetIX+Indexed, No Offset with
EXTExtendedIX2Indexed, 16-Bit OffsetPost Increment
DDDIR to DIRIMDIMM to DIRIX1+Indexed, 1-Byte Offset with
IX+DIX+ to DIR DIX+DIR to IX+Post Increment
INH 1
CLRX
INH 2
CLR
2+ 9E
STOP
IX+D 1
INH 1
IMM 2
1 AF
TXA
INH 2
3 CE
LDX
AIX
DIR 3
Opcode in F0
Hexadecimal
Number of Bytes 1
STX
SUB
3
LDX
IX1 1
4 EF
IX
3 FF
STX
IX2 2
3 HCS08 Cycles
Instruction Mnemonic
IX Addressing Mode
IX
3 FE
LDX
STX
EXT 3
5
JSR
IX1 1
IX2 2
4 DF
IX
5 FD
JSR
4 EE
EXT 3
3 CF
STX
IMM 2
6 ED
LDX
3
JMP
IX1 1
IX2 2
4 DE
IX
3 FC
JMP
JSR
LDX
DIR 3
2 BF
4 EC
EXT 3
3
ADD
IX1 1
IX2 2
6 DD
JSR
DIR 3
2 BE
LDX
2
2+ 9F
WAIT
IX 1
AE
5 CD
JSR
REL 2
IX
3 FB
ADD
JMP
EXT 3
3
ORA
IX1 1
IX2 2
4 DC
JMP
DIR 3
5 BD
BSR
Page 2
INH
4 8F
CLR
IX1 1
1 AD
INH 2
ADD
IX
3 FA
ORA
4 EB
EXT 3
3 CC
JMP
2
NOP
1
5 8E
5 7F
BC
INH
9D
3
MOV
IMD 2
1 6F
1
RSP
IX
4 7E
MOV
DIX+ 3
1 5F
1 9C
INH 1
ADD
DIR 3
3
ADC
IX1 1
IX2 2
4 DB
IX
3 F9
ADC
4 EA
EXT 3
3 CB
ADD
IMM 2
4 E9
ORA
3
EOR
IX1 1
IX2 2
4 DA
IX
3 F8
EOR
ADC
ORA
DIR 3
2 BB
ADD
INH 2
TST
IX1 1
IMM 2
1 AB
SEI
INH 1
CLRH
IX 1
4 7D
TST
MOV
DD 2
5 4F
CLR
1 6D
INH 2
4 D9
3 CA
ORA
IX1 1
IX2 2
EXT 3
2
STA
4 E8
EOR
ADC
DIR 3
2 BA
ORA
2 9B
4 8C
INC
IX1 1
INH 2
INH 1
PSHH
IX 1
5 7C
INC
TSTX
INH 1
6 4E
CPHX
1 6C
INH 2
1 5D
TSTA
DIR 1
3 3E
BIL
DIR 2
5 1F
4 4D
TST
REL 2
DBNZ
1 AA
CLI
3 C9
ADC
IMM 2
IX2 2
EXT 3
IX
3 F7
STA
4 D8
EOR
DIR 3
2 B9
ADC
INH 2
3 9A
6 8B
IX1 2
1 A9
SEC
PULH
IX 1
7 7B
DBNZ
INCX
INH 1
IX1 1
INH 3
1 5C
INCA
DIR 1
3 3D
BMS
DIR 2
5 1E
BRSET7
3
5 2D
BCLR6
DIR 2
5 4C
INC
REL 2
DBNZX
INH 2
2 99
EOR
IMM 2
EXT 3
3 C8
3
LDA
IX1 1
4 E7
STA
IX
3 F6
LDA
IX2 2
4 D7
STA
DIR 3
2 B8
EOR
INH 2
INH 1
4 8A
DEC
4 6B
CLC
INH 1
PSHX
IX 1
IMM 2
1 A8
3 C7
STA
3
BIT
IX1 1
4 E6
LDA
EXT 3
IX
3 F5
BIT
IX2 2
4 D6
LDA
DIR 3
2 B7
AIS
INH 2
3 98
4 89
ROL
5 7A
INH 2
4 5B
DBNZA
5 79
DEC
INH 1
3 C6
LDA
IMM 2
1 A7
TAX
PULX
IX 1
IX1 1
1 6A
DECX
INH 1
DIR 2
3 3C
BMC
DIR 2
5 1D
BRCLR6
3
DBNZ
REL 3
5 2C
BSET6
DIR 2
1 5A
7 4B
LSL
ROL
INH 2
2 97
2 B6
LDA
EXT 2
3
AND
IX1 1
4 E5
BIT
EXT 3
IX
3 F4
AND
IX2 2
4 D5
BIT
DIR 3
3
CPX
IX1 1
4 E4
AND
IX
3 F3
CPX
4 D4
3 C5
BIT
IX1 1
IX2 2
EXT 3
3
SBC
4 E3
CPX
AND
DIR 3
2 B5
IMM 2
5 A6
STHX
4 88
IX1 1
1 69
ROLX
DECA
DIR 1
3 3B
BMI
DIR 2
1 59
INH 1
5 4A
LSL
3 96
INH 3
3 C4
AND
BIT
INH 2
PSHA
IX 1
5 78
INH 2
ROLA
DEC
REL 2
5 2B
BCLR5
DIR 2
5 49
DIR 1
3 3A
BPL
DIR 2
5 1B
BRCLR5
3
5 2A
BSET5
LSLX
INH 1
IX1 1
2 B4
IX2 2
EXT 3
IX
3 F2
SBC
4 D3
CPX
DIR 3
IMM 2
2 A5
TSX
4 87
ASR
1 68
1 95
INH 1
CPX
AND
INH 2
EXT 3
3 C3
IMM 2
2 A4
TXS
PULA
IX 1
5 77
ASR
INH 2
LSLA
ROL
REL 2
1 67
1 94
INH 1
4 86
ROR
IX1 1
CPX
REL 2
TPA
DIR 1
5 76
ROR
ASRX
1 58
DIR 1
3 39
BHCS
DIR 2
1 57
INH 1
LSL
1 66
INH 2
BLE
DIR 3
2 B3
3
CMP
IX1 1
4 E2
SBC
IX
3 F1
CMP
IX2 2
4 D2
SBC
3
SUB
IX1 1
4 E1
CMP
EXT 3
3 C2
SBC
IMM 2
3 A3
INH 2
5 85
CPHX
IMM 2
2 B2
3 F0
SUB
IX2 2
4 D1
CMP
DIR 3
4 E0
SUB
EXT 3
3 C1
CMP
SBC
REL 2
11 93
TAP
IX 1
3 75
CPHX
RORX
ASRA
5 48
REL 2
5 29
BCLR4
DIR 2
1 56
INH 1
DIR 1
3 38
4 65
DIR 3
INH 2
4 84
LSR
IX1 1
2 B1
4 D0
SUB
DIR 3
IMM 2
3 A2
BGT
SWI
IX 1
5 74
LSR
LDHX
RORA
5 47
REL 2
BHCC
DIR 2
5 46
DIR 1
ASR
1 64
3 55
IMM 2
COM
IX1 1
INH 2
5+ 92
4 83
SUB
CMP
REL 2
3 C0
IMM 2
3 A1
BLT
BGND
INH 1
5 73
COM
LSRX
LDHX
ROR
3 37
5 28
DIR 2
3
3 36
BEQ
DIR 2
5 18
4 45
REL 2
5 27
BCLR3
1 54
INH 1
DIR 3
INH 1
INH 2
LSRA
STHX
BNE
DIR 2
5 44
REL 2
COMX
6 91
2 B0
SUB
REL 2
INH 2
1 82
DAA
1 63
INH 1
DIR 1
3 35
BCS
DIR 2
COMA
LSR
REL 2
INH 1
BGE
RTS
IX+ 1
1 72
3 A0
INH 2
5 81
CBEQ
NSA
1 53
DIR 1
3 34
BCC
DIR 2
5 15
BRCLR2
3
COM
5 71
Register/Memory
9 90
RTI
IX 1
IX1+ 2
6 62
INH 1
NEG
CBEQ
DIV
5 43
REL 2
5 24
BSET2
DIR 2
5 52
4 80
IX1 1
4 61
IMM 3
MUL
EXT 1
3 33
BLS
DIR 2
BRSET2
3
REL 3
5 23
5 42
NEG
CBEQX
IMM 3
LDHX
5 70
INH 2
4 51
CBEQA
DIR 3
3 32
NEGX
INH 1
5 41
CBEQ
BHI
DIR 2
5 13
BRCLR1
3
3 31
Control
1 60
NEGA
DIR 1
REL 3
5 22
BSET1
1 50
NEG
BRN
DIR 2
5 40
REL 2
5 21
BCLR0
DIR 2
Read-Modify-Write
3 30
BRA
DIR 2
5 11
BRCLR0
3
5 20
DIR 2
3
Branch
5 10
2
STX
IX1 1
IX
Central Processor Unit (CPU)
130
Table 6-13. Opcode Map (Sheet 1 of 2)
Freescale Semiconductor
Table 6-13. Opcode Map (Sheet 2 of 2)
Bit-Manipulation
Branch
Read-Modify-Write
Control
9E60
Register/Memory
6
9ED0
NEG
3
9E61
4
6
4
6
9E64
4
6
3
4
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9E66
6
9E67
4
6
9E68
4
6
4
6
9E6A
6
8
9E6C
SP1
5 9EEA
SP1
5 9EEB
ADD
4
4
ORA
SP2 3
9EDB
SP1
4
ADC
ORA
DBNZ
4
SP1
SP2 3
4
4
5 9EE9
9EDA
SP1
9E6B
SP2 3
4
DEC
3
SP1
EOR
ADC
SP1
4
STA
5 9EE8
9ED9
ROL
3
SP1
5 9EE7
EOR
SP1
9E69
4
LDA
SP2 3
9ED8
LSL
3
5 9EE6
STA
SP1
SP1
SP2 3
9ED7
ASR
3
4
BIT
LDA
SP1
SP1
SP2 3
9ED6
ROR
3
4
5 9EE5
BIT
4
SP1
AND
SP2 3
9ED5
6
CPHX
SP1 3
5 9EE4
AND
SP1
4 9EF3
CPX
SP2 3
9ED4
LSR
SP1
5 9EE3
CPX
SP1
4
SBC
SP2 3
9ED3
COM
3
SP1
5 9EE2
SBC
4
4
CMP
SP2 3
9ED2
9E63
SP1
5 9EE1
CMP
SP1
4
SUB
SP2 3
9ED1
CBEQ
4
5 9EE0
SUB
SP1
4
ADD
SP2 3
SP1
6
INC
3
SP1
9E6D
5
TST
3
SP1
9EAE
5 9EBE
LDHX
9E6F
6 9ECE
LDHX
IX 4
IX2 3
6
5 9EDE
LDHX
INHInherentRELRelativeSP1Stack Pointer, 8-Bit Offset
IMMImmediateIXIndexed, No OffsetSP2Stack Pointer, 16-Bit Offset
DIRDirectIX1Indexed, 8-Bit OffsetIX+Indexed, No Offset with
EXTExtendedIX2Indexed, 16-Bit OffsetPost Increment
DDDIR to DIRIMDIMM to DIRIX1+Indexed, 1-Byte Offset with
IX+DIX+ to DIR DIX+DIR to IX+Post Increment
131
Note: All Sheet 2 Opcodes are Preceded by the Page 2 Prebyte (9E)
4
Prebyte (9E) and Opcode in 9E60
6 HCS08 Cycles
Hexadecimal
Instruction Mnemonic
NEG
Number of Bytes 3
SP1 Addressing Mode
SP1
4 9EFF
STX
SP2 3
5
LDHX
SP1 3
5 9EEF
STX
SP1
4 9EFE
LDX
SP2 3
9EDF
CLR
3
5 9EEE
LDX
IX1 4
SP1 3
5
STHX
SP1
Instruction Set Summary
2
Central Processor Unit (CPU)
6.7 Assembly Language Tutorial
While most readers of this book already have a basic understanding of assembly language programming,
assemblers written by different third-party development tool vendors often have subtle differences in
syntax rules. This section describes the directives, conventions, and syntax rules that apply to the code
examples used in this book. If a novice user uses the same Metrowerks assembler that we used, this
section provides enough basic information to start writing simple programs. In all cases, the user should
refer to the documentation that came with their particular assembler for more detailed information.
Code examples in this book conform to the source forms shown in the tables at the bottom of each
instruction page in Appendix A Instruction Set Details. For readability and consistency with the instruction
documentation, all instruction mnemonics use uppercase. Most assemblers ignore case for mnemonics,
and many programmers prefer to use lowercase to simplify the process of typing long source files.
6.7.1 Parts of a Listing Line
The fields of the following example line from a Metrowerks CodeWarrior code listing are numbered and
explained in the text that follows. This explanation is provided as a reference for the code examples used
throughout this manual.
34 C000 A4 7F
upcase:
and
----- ---- --------- ------------ ----1
2
3
4
5
#$7F
--------6
;forces MSB to 0
----------------------7
This second code listing is from the P&E Microcomputer Systems CASMS08Z assembler. P&E includes
the same fields 1–7 as the previous figure, but they are in slightly different order and there is an optional
field #8 that shows the number of CPU bus cycles for each instruction.
C000 [02] A47F
34
----- ---- --------- ---2
8
3
1
upcase:
and
#$7F
------------ ------ -----------4
5
6
;forces MSB to 0
-----------------7
Fields 1, 2, 3, and 8 are generated by the assembler while fields 4, 5, 6, and 7 are part of the source file
provided by the user:
• Field 1 (491) is a line number which the assembler added as a reference. This line number is not
used by the MCU, but it is a useful reference when people are discussing the program listing.
• Field 2 (C000) is the address where this instruction starts in memory.
• Field 3 (A4 7F) is the object code for the instruction on this listing line. $A4 is the opcode for the
AND instruction, and $7F is the immediate data value that will be compared to the accumulator (A).
• Field 4 (upcase:) is a label which the assembler equates to the address shown in field 1. Most
assemblers require the colon at the end of a label (where it is defined but not where it is used as
an operand in an instruction). This colon is not considered part of the label. Some programmers
prefer to put labels on a separate line by themselves so they can use longer, more descriptive
names while keeping the instruction mnemonics in field 6 lined up along a vertical line that isn’t too
far to the right in the listing.
• Field 5 (and) is the instruction mnemonic. Most assemblers ignore the case of the mnemonic, but
labels are usually case sensitive.
• Field 6 (#$7F) is the operand field. In this case, the immediate value 7F is hexadecimal as indicated
by the $ (dollar) symbol. The # (pound) symbol tells the assembler to use immediate addressing
mode.
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•
•
Field 7 is a comment. Comments should start with a semicolon character. Everything else to the
end of the line is a comment that is not used by the assembler or the MCU. It is just for the benefit
of the programmer and others who need to understand the program.
Field 8 ([02]) is an optional field which tells how many bus cycles this instruction takes. Not all
assemblers provide this field. The P&E assembler can provide this field. This field is usually left out
of listings, but it is included here because it can be helpful while a programmer is learning the
instruction set.
6.7.2 Assembler Directives
This section describes a minimum set of assembler directives to allow a novice user to start writing basic
assembly language programs. These basic directives should be supported by any HCS08 assembler.
Typical assemblers also include other directives, some of which may be specific to a particular vendor’s
assembler (especially in the areas of macros and conditional assembly). Always refer to the
documentation that came with the assembler you are using for complete information.
P&E Microcomputer Systems makes a distinction between directives and pseudo-ops, while some other
vendors use the term directives to describe all of these special operators. Pseudo-ops are reserved
command words which go in the instruction mnemonic field. Pseudo-ops are used to set the starting
location of a program, to equate a label to a value, to define the location of program variables in memory,
or to reserve space for RAM variables. Directives are more general commands to control printing and
configuration options for the assembler. In most assemblers, directives are placed in the same field as
the instruction mnemonics.
6.7.2.1 BASE — Set Default Number Base for Assembler
Most assemblers use decimal as the default base but P&E assemblers default to treating operands with
no prefix as hexadecimal numbers. For all of the examples in this book, we want the default number base
to be decimal, so it is good practice to use the following directive at the beginning of all of our source files.
base
10t
;change default to decimal
6.7.2.2 INCLUDE — Specify Additional Source Files
It is often inconvenient to place all source code for a project into a single file. This directive allows you to
split the project into two or more separate files. The main file would use INCLUDE directives in the main
source file to indicate where the other files should be incorporated into the project. When the assembler
encounters an INCLUDE directive, it switches its input stream to the included file until an end-of-file is
detected. This effectively replaces the include directive line with the referenced file.
A common use for this directive is to include a chip definition file (sometimes called an equate file).
Freescale provides free equate files for its MCUs, so you can use register and bit names in your programs
rather than addresses and bit numbers which are not as readable.
This example just uses the file name but you can specify an explicit path for the file if it isn’t located in the
main project directory.
include "9S08GB60_v1.equ"
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6.7.2.3 NOLIST/LIST — Turn Off or Turn On Listing
The assembler reads a source file and generates a composite listing file while it assembles the source
file into an object code file for a program. The listing file is a plain text file which includes the object code
and generated line numbers in addition to the information from the original source file. The NOLIST and
LIST directives allow the programmer to control the production of the listing file.
The most common use of these directives is to suppress the listing while the assembler processes the
MCU equate file. This is common because the contents of the equate file are well understood and
suppressing this listing can easily save 15 to 20 pages of listing. The programmer may list the equate file
separately and keep it on hand for reference.
nolist
;turn off listing
include "9S08GB60_v1.equ"
list
;turn listing back on
6.7.2.4 ORG — Set Program Starting Location
During assembly the assembler maintains a “location counter” which keeps track of the next available
memory location where code or variables could be stored. The ORG directive sets this location counter
to a specific address value. This does not produce any actual code in the object file. Rather, it tells the
assembler where the next byte of code or data should be located in memory.
Every program needs at least one ORG directive, and programs often include several ORG directives. A
typical program includes one ORG directive to set the starting location for variables in RAM. After
declaring all RAM variables, a second ORG directive is used to establish the starting location for the
application program in ROM or FLASH memory. A third ORG directive is often used to set the location
counter to the start of the interrupt vector space.
org
RamStart
;start of RAM variables
; ds.b directive doesn't produce any object code.
; Just reserves uninitialized named locations for future use.
resrvBytes: ds.b
8
;reserve space for 8 vars
;for move examples setup 2 10-byte blocks that overlap
moveBlk1:
ds.b
10
;reserve 10 bytes for block 1
blk1end:
equ
*
;* means 'here'
org
Startup:
; Setup options for
lda
sta
; Set stack pointer
ldhx
txs
RomStart
;set program starting point
;ex. label on separate line
COP and STOP in SIMOPT
#initSIMOPT
;settings for COP & STOP
SOPT
;SIM options (write once)
to last (highest) RAM location
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
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org
Vrti-2
;2 before first vector
; leave room for resetISR and defaultISR
resetISR:
dc.b
illegalOp
;force ilop reset
defaultISR: rti
;just return
; even unused vectors should point at some handler
vecRti:
vecIic:
vecAtd:
vecKeyboard:
vecSci2tx:
vecSci2rx:
vecSci2err:
vecSci1tx:
vecSci1rx:
vecSci1err:
vecSpi:
vecTpm2ovf:
vecTpm2ch4:
vecTpm2ch3:
vecTpm2ch2:
vecTpm2ch1:
vecTpm2ch0:
vecTpm1ovf:
vecTpm1ch2:
vecTpm1ch1:
vecTpm1ch0:
vecIcg:
vecLvd:
vecIrq:
vecSwi:
vecReset:
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
defaultISR
resetISR
defaultISR
defaultISR
Startup
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;handle unused interrupts
;force an ilop reset
;handle unused interrupts
;handle unused interrupts
;reset starting point
6.7.2.5 EQU — Equate a Label to a Value
This directive tells the assembler what value or address should be associated with a particular label. For
example:
illegalOp:
equ
$8D
;$8D is an unused opcode
tells the assembler that the label illegalOp is equivalent to the hexadecimal value $8D. The next example
illustrates the more interesting case where an asterisk (*) in the operand field is interpreted by the
assembler to mean “the current location counter value.”
52
53
54
55
56 0080
57
58 0088
59
0000 0092
org
RamStart
;start of RAM variables
; ds.b directive doesn't produce any object code.
; Just reserves uninitialized named locations for future use.
resrvBytes: ds.b
8
;reserve space for 8 vars
;for move examples setup 2 10-byte blocks that overlap
moveBlk1:
ds.b
10
;reserve 10 bytes for block 1
blk1end:
equ
*
;* means 'here'
In this example, the ds.b directive in line 58 set aside 10 (decimal) locations from address $0088–$0091
so at the time the assembler read the “blk1end: EQU *...” line, the location counter was equal to $0092.
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6.7.2.6 dc.b — Define Byte-Sized Constants in Memory
dc.b is used to define 8-bit constant values in memory. This directive is similar to the FCB directive used
by some assemblers. In its simplest form, the dc.b directive sets a single memory location equal to a
specified 8-bit value. The directive can (and usually does) have a label which associates the address,
where the constant is stored, to the label.
108
109
110
111
112
113
114 1080 55
******************************************************************
* Define ROM (flash) constants for use in examples
******************************************************************
hexByte:
org
RomStart
;set program starting point
dc.b
$55
;$ prefix means hexadecimal
In this example, the dc.b directive defined a constant with the value $55 at location $1080. The ORG
directive set the location counter to $1080, so this is the address that was used for the dc.b directive.
Since the dc.b used one byte of memory, the location counter is automatically advanced by one, so it
points at $1081 after the dc.b directive. The label hexByte is set equal to the address $1080 which is the
address where the constant ($55) is located in memory.
115
116
117
118
119
120
1081
1082
1083
1084
1087
108B
108F
121 1091
0C
5A
35
1122
0000
4164
2061
6C65
00
decimalByte:
binaryByte:
asciiByte:
33
multiBytes:
1087 moveBlk3:
616D stringBytes:
7070
dc.b
dc.b
dc.b
dc.b
equ
dc.b
12
%01011010
'5'
$11,$22,$33
*
'Adam apple'
;no prefix means decimal
;% prefix means binary
;' prefix means ASCII
;commas separate operands
;3rd block for move examples
;string makes ASCII bytes
dc.b
0
;null terminator
This example demonstrates various forms of the operand field in dc.b directives.
• Line 115 shows a decimal constant (12) and the assembler stores this in memory as $0C which is
the hexadecimal equivalent of decimal 12.
• Line 116 shows the % prefix which indicates a binary value.
• In line 117, the character 5 is surrounded by single quotes to indicate an ASCII value. The
assembler stores $35 which is the hexadecimal equivalent of the ASCII character for the number 5.
• Line 118 shows that the operand field can consist of a list of separate constants separated by
commas. Notice three bytes were stored in memory.
• Line 120 shows an ASCII string may be enclosed in single quotes. The assembler will store the
hexadecimal equivalent of each ASCII character in successive memory locations (one byte per
character in the string). The quotes are not included in the constants that are stored in memory. In
the case of a string or when more than four bytes of constants are defined on one source code line,
the listing will have multiple lines to allow the object code field to line-wrap to list all of the constant
values stored in memory. (See the two extra lines between listing lines 140 and 141 which are
considered part of line 140.)
6.7.2.7 dc.w — Define 16-Bit (Word) Constants in Memory
dc.w is used to define 16-bit constant values in memory. This directive is similar to the FDB directive used
by some assemblers. In its simplest form, the dc.w directive sets a pair of memory locations to a specified
16-bit value (with the first high-order 8 bits going to the current address pointed to by the location counter
and the second low-order value going to the next higher memory address location). The directive can (and
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usually does) have a label which associates the address, where the upper 8-bit half of the constant is
stored, to the label.
123 1092 1234
hexWord:
124 1094 1092
addrWord:
125 1096 5678 9ABC multiWord:
dc.w
dc.w
dc.w
$1234
hexWord
$5678,$9ABC
;takes up two bytes
;label used as 16-bit addr
;dc.w with multiple operands
Line 123 is a simple case where the hexadecimal constant $1234 is stored in memory, $12 at address
$1092 and $34 at $1093. The label hexWord is set equal to $1092 by the assembler because this is the
memory address where this constant is stored in memory. Line 124 uses the label hexWord in the
operand field of a dc.w directive and the assembler stores the equivalent hexadecimal value $1092, $10
at address $1094 and $92 at address $1095. Line 125 demonstrates that the operand field of an dc.w
directive can consist of a list of constants separated by commas. The constants $5678 and $9ABC are
shown in the object code field of the listing line.
6.7.2.8 ds.b — Define Storage (Reserve) Memory Bytes
ds.b is used to set aside a specified number of 8-bit memory locations for use as program variables. This
directive is similar to the RMB directive in some older assemblers. There is also a ds.w directive that is
used to set aside a specified number of 16-bit memory locations for use as program variables. Unlike the
dc.b and dc.w directives discussed in the previous two sections, the ds.b and ds.w directives do not
produce any object code. ds.b tells the assembler to associate a label to the current address pointed to
by the location counter and then to adjust the location counter by the number of bytes set aside by the
ds.b directive so the location counter points at the next available memory location. The ds.b directive can
be used without a label to just move the location counter, but this is rarely done. It is most often used to
set aside memory space for a single named program variable, but it can also be used to set aside space
for a larger data structure or table.
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
******************************************************************
* Define RAM variables for use in examples
******************************************************************
org
RamStart
;start of RAM variables
; ds.b directive doesn't produce any object code.
; Just reserves uninitialized named locations for future use.
0080
resrvBytes: ds.b
8
;reserve space for 8 vars
;for move examples setup 2 10-byte blocks that overlap
0088
moveBlk1:
ds.b
10
;reserve 10 bytes for block 1
0000 0092 blk1end:
equ
*
;* means 'here'
; another way to define a RAM block
0000 000A blk2size:
equ
10
;size in bytes
0092
moveBlk2:
ds.b
blk2size
;reserve bytes for block 2
0000 009C blk2end:
equ
(moveBlk2+blk2size) ;end tracks size
009C
0000
0000
0000
0000
0007
0080
0006
0040
009D
; Setup a flag byte with multiple 1-bit flags
; name prefixed by m is used to define a mask for logical
; instructions like AND or ORA; the bit name without the m prefix
; defines a bit number for BCLR, BSET, BRCLR, and BRSET
flags:
ds.b
1
;reserves a byte
SCIready:
equ
7
;bit number
mSCIready:
equ
%10000000
;bit 7 mask
OneSecond:
equ
6
;bit number
mOneSecond: equ
%01000000
;bit 6 mask
directByte:
ds.b
1
;a variable in direct space
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In this example, the ORG directive is used to establish the location counter value for the assembler. Line
56 sets aside eight bytes of memory (locations $0080 through $0087). The label resrvBytes is set equal
to the starting address for the block or $0080. Line 75 is a much simpler and more common use of ds.b
where memory location $009D is set aside for a program variable named directByte. Lines 69 through 73
show an ds.b directive used to set aside an 8-bit location for the program variable named “flags” and then
the next four EQU directives are used to identify specific bits within this flag byte.
In the HCS08 architecture, the BCLR, BSET, BRCLR, and BRSET instructions use the bit number (0–7)
to choose a specific opcode that is defined to work with the selected bit within a memory location. Other
instructions such as AND and ORA use bit masks to identify one or more bit locations to be operated on.
For this reason, bits are defined in two slightly different ways:
• By convention, we use a normal label such as SCIready to define the bit number
• We use the same label preceded by a lowercase m to define the bit mask
In a program, we would then use the plain bit name form whenever we use it in a BCLR, BSET, BRCLR,
or BRSET instruction. We use the bit name with a prefix of lowercase m everywhere else. Following a
convention such as this helps the programmer avoid confusion and errors. This convention is used in
equate files provided by Freescale so it is suggested that the same convention be followed in defining
other bit labels.
6.7.3 Labels
User-defined labels are used by the assembler to make the code more readable and to simplify the task
of writing programs. For example, it is easier for a programmer to remember a text label like “Start” than
a 4-digit hexadecimal address which may change as instructions are added or removed from the program.
These labels are significant to the assembler, but not to the actual MCU. The source forms shown on the
instruction pages in Appendix A Instruction Set Details never include any labels. In fact, the source forms
only show the instruction mnemonic and a representative operand field. A real source program should
usually also include a comment field and sometimes a label field.
Some assemblers ignore case in labels so something like “RAM” would be indistinguishable from “ram”
or “Ram.” Other assemblers let the programmer set a control flag to decide whether case matters. Always
check the documentation for the assembler you are using to be sure you understand how it treats
uppercase and lowercase letters.
Older assemblers limited the size of labels to six or eight characters, but modern assemblers allow much
longer labels. A few assemblers allow very long names but only consider the first several characters as
significant. For example, an assembler that only considered the first 10 characters would not see any
difference between the labels LongLabel37 and LongLabel38 although it might consider
VeryVeryLongLabel to be acceptable. Again, you should consult the documentation for your assembler.
In most assemblers, labels may contain any letters, numbers, or the symbols, underscore (_), or period
(.), but the label must start with a letter or underscore (_). Some assemblers allow other characters, but
it is safer to limit yourself to these choices to assure easy portability to other assemblers. Notice that labels
must NOT contain any space characters because the assembler would not be able to tell this from two
separate labels. In this book, underscore characters are not used because some people think they make
programs less readable. (This is a subjective opinion and other users think underscore characters
improve readability.) Instead, a combination of uppercase and lowercase is used here to make multiword
labels, for example, RamLast where an underscore proponent might use ram_last.
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A label can be defined only once, but it may be used any number of times within a program. Where a label
is defined, the label name must start in the first column of the source line, and most assemblers require
a colon after the label where it is defined as in:
waitRDRF:
brclr
RDRF,SCI1S1,waitRDRF ;loop till RDRF set
Notice that where the label is used in the operand field, there is no colon.
Where longer labels are used, some programmers prefer to place the label on a separate line above the
line to which the label refers.
131
132
133
134 109A A6 00
Startup:
;ex. label on separate line
; Setup options for COP and STOP in SIMOPT
lda
#initSIMOPT
;settings for COP & STOP
The label is defined on line 131 and in this case there is an optional comment on the same line. Line 132
is a blank line which produces no object code and is simply used to create a visual separation. Line 133
is a whole-line comment which also does not produce any object code. Line 134 is the first line after the
label in line 131 that has any object code, so this is the address assigned to the label by the assembler.
6.7.4 Expressions
The operand field of an instruction or directive can contain an explicit value (using various number bases
or conversions), an expression, or a label. Trivial expressions such as RamStart+1 do not require
parentheses or brackets. In the P&E assembler, complex expressions must be enclosed in curly braces
as in {moveBlk1–RamStart+3}. Most assemblers use parentheses to enclose complex expressions.
Most assemblers allow complex mathematical and logical expressions in any operand field, but practical
application programs rarely use complex nested expressions. The most common expressions are small
constant offsets to identify a location within a multibyte variable or data structure or to identify the next
location past some label (label+1).
137 109F 45 1080
138 10A2 94
ldhx
txs
#RamLast+1
;point one past RAM
;SP<-(H:X-1)
In this example, RamLast was equated to the address $107F. We know the TXS instruction is going to
automatically subtract one from the address in H:X, so we compensate for this by loading H:X with the
address after RamLast (that is RamLast+1). This is an example of a trivial expression that does not need
to be enclosed in parentheses.
297
298
299
300
301
302
303
304
305
306
1172
1174
1176
1178
117A
117C
117E
1180
1182
B6
BB
B7
B6
A9
B7
B6
A9
B7
A0
A8
A8
A7
00
A7
A6
00
A6
; add 8-bit operand
lda
add
sta
lda
adc
sta
lda
adc
sta
to 24-bit sum
oprA
;8-bit operand to A
sum24+2
;LS byte of 24-bit sum
sum24+2
;update LS byte
sum24+1
;middle byte of 24-bit sum
#0
;propigate any carry
sum24+1
;update middle byte
sum24
;get MS byte of 24-bit sum
#0
;propigate carry into MS byte
sum24
;update MS byte
In this example, the label sum24 identifies a 24-bit variable located in three successive bytes of memory.
The most significant byte is located at address sum24, the middle byte is at sum24+1 and the least
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Central Processor Unit (CPU)
significant byte is located at sum24+2. This is another example of trivial expressions not requiring
enclosure in parentheses.
-----
58 0088
59
0000 0092
"
"
"
"
120 1087 4164 616D
108B 2061 7070
108F 6C65
121 1091 00
"
"
"
"
288
289 1165 45 0088
290 1168 D6 0FFF
291 116B 27 05
292 116D E7 00
293 116F 5C
294 1170 20 F6
295
moveBlk1:
ds.b
blk1end:
equ
"
"
stringBytes: dc.b
10
*
"
'Adam apple'
;reserve 10 bytes for block 1
;* means 'here'
"
;string makes ASCII bytes
dc.b
0
;null terminator
"
"
"
"
; block move example to move a string to a RAM block
ldhx
#moveBlk1
;point at destination block
movLoop1:
lda
(stringBytes-moveBlk1),x ;get source byte
beq
dunLoop1
;null terminator ends loop
sta
0,x
;save to destination block
incx
;next location (assumes DIR)
bra
movLoop1
;continue loop
dunLoop1:
In line 290 the expression (stringBytes-moveBlk1) is enclosed in parentheses because it involves two
labels and the assembler considers this a “complex” expression. The assembler computes the difference
of the two 16-bit addresses represented by stringBytes = $1087 and moveBlk1 = $0088 ($1087 – $0088
= $0FFF). The result of the assembler’s computation can be seen after the opcode (D6) in the object code
field of the listing in line 290.
mOR:
mNF:
mFE:
mPF:
"
equ
equ
equ
equ
"
bit
415 11F3 A5 0F
%00001000
;receiver over run
%00000100
;receiver noise flag
%00000010
;receiver framing error
%00000001
;received parity failed
"
"
#(mOR+mNF+mFE+mPF) ;mask of all error flags
In this example, we added the separate bit masks with the arithmetic addition operator. Because each of
the four bit masks is an 8-bit value with a different single bit set to 1, this is equivalent to combining the
masks with logical OR operators, but the + (plus) is more universal among different assemblers than the
OR operator.
6.7.5 Equate File Conventions
Most code for this book was assembled along with an included equate file which defines all MCU registers
and control bits by the names used in the data sheet for a specific HCS08 derivative. In that equate file,
which is described in greater detail in Appendix B Equate File Conventions, register names use all
uppercase letters to match the data sheets. Program labels use a combination of uppercase and
lowercase letters. This is not a requirement of the assembler, but rather a convention chosen to make
these code listings more consistent with chip documentation.
Bit names are defined in two ways:
• The bit name with no prefix is equated to the bit number (0–7).
• The name preceded by a lower-case m is equated to a bit position mask.
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Assembly Language Tutorial
This excerpt from the equate file for the MC9S08GB60 shows the SCI status register with its bits defined
according to this convention.
SCI1S1:
equ
$1C
;SCI1 status register 1
SCI2S1:
equ
$24
;SCI2 status register 1
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
TDRE:
equ
7
;(bit #7) Tx data register empty
TC:
equ
6
;(bit #6) transmit complete
RDRF:
equ
5
;(bit #5) Rx data register full
IDLE:
equ
4
;(bit #4) idle line detected
OR:
equ
3
;(bit #3) Rx over run
NF:
equ
2
;(bit #2) Rx noise flag
FE:
equ
1
;(bit #1) Rx framing error
PF:
equ
0
;(bit #0) Rx parity failed
; bit position masks
mTDRE:
equ
%10000000
;transmit data register empty
mTC:
equ
%01000000
;transmit complete
mRDRF:
equ
%00100000
;receive data register full
mIDLE:
equ
%00010000
;idle line detected
mOR:
equ
%00001000
;receiver over run
mNF:
equ
%00000100
;receiver noise flag
mFE:
equ
%00000010
;receiver framing error
mPF:
equ
%00000001
;received parity failed
The next example shows the use of the bit number variation of a bit definition. The operand field of the
BRCLR instruction includes three items separated by commas. RDRF is converted to the number 5 which
tells the assembler to use the bit-5 variation of the BRCLR instruction (opcode = $0B). The next item,
SCI1S1 tells the assembler the operand to be tested is located at the direct addressing mode address
$001C (just 1C in the object code). The last item, waitRDRF, tells the assembler to branch back to the
same BRCLR instruction if the RDRF status bit is found to be still clear (0).
450 120A 0B 1C FD
waitRDRF:
brclr
RDRF,SCI1S1,waitRDRF ;loop till RDRF set
The next example shows an expression combining the bit masks for the OR, NF, FE, and PF status bits.
In this example, we used the bit names with a preceding m to get the bit position mask rather than the bit
number. We used a simple addition operator (+) to combine the bit masks. Although a logical OR might
have been more correct in this case, not all assemblers use the same character to indicate the logical OR
operation, so the + is more portable among assemblers. We can use the + because we know the
individual bit masks do not overlap.
413
414 11F1 B6 1C
415 11F3 A5 0F
416 11F5 26 00
417
; BIT example to check several error flags in SCI status reg
lda
SCI1S1
;read SCI status register
bit
#(mOR+mNF+mFE+mPF) ;mask of all error flags
bne
sciError
;branch if any flags set
; A still contains undisturbed status register
6.7.6 Object Code (S19) Files
The ultimate goal of an assembler is to convert a source code file into the object code that the MCU needs
to execute a program. The assembler optionally produces a listing file which acts as a form of primary
documentation for the program. In this section we briefly describe the source and listing files and provide
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Central Processor Unit (CPU)
a more detailed description of the object code file, which is sometimes called a “dot S 1 9 file.” This name
comes from the .s19 filename extension and the internal format of the file.
The whole programming process starts with a planning effort which may involve flowcharts or other forms
of documentation which describe what is to be done and roughly how the programmer plans to do it. The
first item directly related to the final program is the source file which the programmer types into a text file.
The source file uses instruction mnemonics and special syntax rules that are understood by the
assembler.
The source file should also include generous comments to help humans who must understand and
maintain the program. The following is an example of a short source program.
******************************************************************
* Title: s19example.asm
Copyright (c) Freescale 2003
******************************************************************
* Author: Jim Sibigtroth - Freescale
*
* Description: This is not a complete program, rather it is just
* enough code to demonstrate the relationship between the various
* files in a typical MCU programming project (especially .s19
* files).
*
******************************************************************
org
$C000
******************************************************************
* upcase - convert ASCII character in A to upper case
* on entry A contains an unknown character
* first strip MSB (AND with $7F) to get 7-bit ASCII
* if A > or = "a" and < or = "z", subtract $20 (A=$41, a=$61)
* other values unchanged except MSB stripped off (forced to 0)
******************************************************************
upcase:
and
#$7F
;forces MSB to 0
cmp
#'a'
;check for < "a"
blt
xupcase
;done if too small
cmp
#'z'
;check for > "z"
bgt
xupcase
;done if too big
sub
#$20
;convert a-z to A-Z
xupcase:
rts
;done
*********************
******************************************************************
* ishex - check character for valid hexadecimal (0-9 or A-F)
* on entry A contains an unknown upper-case character
* returns with original character in A and Z set or cleared
* if A was valid hexadecimal then Z=1, otherwise Z=0
******************************************************************
ishex:
psha
;save original character
cmp
#'0'
;check for < ASCII zero
blo
nothex
;branches if C=0 (Z also 0)
cmp
#'9'
;check for 0-9
bls
okhex
;branches if ASCII 0-9
cmp
#'A'
;check for < ASCII A
blo
nothex
;branches if C=0 (Z also 0)
cmp
#'F'
;check for A-F
bhi
nothex
;branches if > ASCII F
okhex:
clra
;forces Z bit to 1
nothex:
pula
;restore original character
rts
;return Z=1 if char was hex
*********************
Figure 6-6. Demonstration Code
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Assembly Language Tutorial
The assembler is a third-party development tool which is a computer program that runs on a personal
computer or workstation and translates source code files into the hexadecimal numbers to be stored into
the memory of the target MCU. The assembler can be requested to produce a listing file which includes
both the original source program and a representation of the machine code meaning of each source line.
This listing file is intended to act as documentation for the application program. The listing includes more
information than the source file, such as the addresses of labels and the opcodes that each instruction
mnemonic translates to.
The following code example is the listing file generated by assembling the source file shown in the
previous example.
1
2
3
4
5
6
7
8
9
10
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
C000
C002
C004
C006
C008
C00A
C00C
C00D
C00E
C010
C012
C014
C016
C018
C01A
C01C
C01E
C01F
C020
A4
A1
91
A1
92
A0
81
87
A1
25
A1
23
A1
25
A1
22
4F
86
81
7F
61
06
7A
02
20
30
0D
39
08
41
05
46
01
******************************************************************
* Title: s19example.asm
Copyright (c) Freescale 2003
******************************************************************
* Author: Jim Sibigtroth - Freescale
*
* Description: This is not a complete program, rather it is just
* enough code to demonstrate the relationship between the various
* files in a typical MCU programming project (especially .s19
* files).
*
******************************************************************
org
$C000
******************************************************************
* upcase - convert ASCII character in A to upper case
* on entry A contains an unknown character
* first strip MSB (AND with $7F) to get 7-bit ASCII
* if A > or = "a" and < or = "z", subtract $20 (A=$41, a=$61)
* other values unchanged except MSB stripped off (forced to 0)
******************************************************************
upcase:
and
#$7F
;forces MSB to 0
cmp
#'a'
;check for < "a"
blt
xupcase
;done if too small
cmp
#'z'
;check for > "z"
bgt
xupcase
;done if too big
sub
#$20
;convert a-z to A-Z
xupcase:
rts
;done
*********************
******************************************************************
* ishex - check character for valid hexadecimal (0-9 or A-F)
* on entry A contains an unknown upper-case character
* returns with original character in A and Z set or cleared
* if A was valid hexadecimal then Z=1, otherwise Z=0
******************************************************************
ishex:
psha
;save original character
cmp
#'0'
;check for < ASCII zero
blo
nothex
;branches if C=0 (Z also 0)
cmp
#'9'
;check for 0-9
bls
okhex
;branches if ASCII 0-9
cmp
#'A'
;check for < ASCII A
blo
nothex
;branches if C=0 (Z also 0)
cmp
#'F'
;check for A-F
bhi
nothex
;branches if > ASCII F
okhex:
clra
;forces Z bit to 1
nothex:
pula
;restore original character
rts
;return Z=1 if char was hex
*********************
Figure 6-7. Listing File
The fields of this listing are explained in 6.7.1 Parts of a Listing Line.
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Central Processor Unit (CPU)
The MCU expects the program to be a series of 8-bit values in memory. So far, our program still looks as
if it was written for people. The version the computer needs to load into its memory is called an object
code file. For Freescale microcontrollers, the most common form of object code file is the .s19 or S-record
file. The assembler can be directed to optionally produce a listing file and/or an object code file.
An S-record file is an ASCII text file that can be viewed by a text editor or word processor. Do not edit
these files because the structure and content of the files are critical to their proper operation.
Each line of an S-record file is a record. Each record begins with a capital letter S followed by a code
number from 0 to 9. The only code numbers that are important in this application are S0, S1, and S9
because other S-number codes apply only to larger systems.
• S0 is an optional header record that may contain the name of the file for the benefit of humans that
need to maintain these files.
• S1 records are the main data records.
• An S9 record is used to mark the end of the S-record file.
For the work we are doing with 8-bit microcontrollers, the information in the S9 record is not important,
but an S9 record is required at the end of the S-record file. Figure 6-8 shows the syntax of an S1 record.
TYPE
LENGTH
ADDRESS
OBJECT CODE DATA
CHECKSUM
S1 13 C0 00 A4 7F A1 61 91 06 A1 7A 92 02 A0 20 81 87 A1 30 28
CHECKSUM = ONE’S COMPLEMENT OF THE SUM OF ALL OF THESE BYTES
Figure 6-8. Syntax of an S1 Record
All of the numbers in an S-record file are in hexadecimal. The type field is S0, S1, or S9 for the S-record
files used here. The length field is the number of pairs of hexadecimal digits in the record excluding the
type and length fields. The address field is the 16-bit address where the first data byte will be stored in
memory. Each pair of hexadecimal digits in the machine code data field represents an 8-bit data value to
be stored in successive locations in memory. The checksum field is an 8-bit value that represents the
one’s complement of the sum of all bytes in the S-record except the type and checksum fields. This
checksum is used during loading of the S-record file to verify that the data is complete and correct for each
record.
S123C000A47FA1619106A17A9202A0208187A130250DA1392308A1412505A14622014F86F6
S104C020819A
S9030000FC
Figure 6-9. S19 Example
You can compare the values in the S-record file with those in the object code field of the listing in Figure
6-9. The ORG directive in line 49 of Figure 6-7 established the starting address at $C000.
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Chapter 7
Development Support
7.1 Introduction
Development support systems in the HCS08 Family include the background debug controller (BDC) and
the on-chip debug module (DBG). This architecture marks a major change in the way MCU systems are
developed due to advances in the processing technology used to make these devices.
In the past, most development was based on an external tool having access to the address and data
buses of the target MCU. This allowed the external tool to monitor cycle-by-cycle activity and intervene at
critical points to stop normal execution of the application program. This style of debug has become
increasingly difficult to support due to the higher speeds and smaller packages of more modern MCUs.
At the same time, the cost of logic circuitry within the MCU has decreased as process improvements and
shrinks have allowed more circuitry per unit of die area. Due to mechanical constraints, pads for wire-bond
connections have not shrunk as quickly as other circuitry. In today’s technology, a few extra pins cost
more than a few thousand logic transistors worth of internal circuitry. Moving the development circuitry
inside the MCU to avoid the need for external pins for the address and data buses is now the most
cost-effective method.
The BDC provides a single-wire debug interface to the target MCU. This interface provides a convenient
means for programming the on-chip FLASH and other non-volatile memories. Also, the BDC is 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.
Most HCS08 devices provide two other features related to development. The BDFR control bit in the
SBDFR register (usually located at $1801) is a write-only bit that allows a host development system to
reset the target MCU with a serial memory modify command through the background debug interface.
BDFR cannot be written by user software, so the target MCU cannot be reset accidentally even if user
code runs away due to some programming bug. The second development feature is a part identification
number in the SDIDH:SDIDL register pair (usually located at $1806, $1807). The upper four bits of SDIDH
hold the silicon mask set revision number (0–F), and the remaining 12 bits of the SDIDH:SDIDL register
pair hold a 12-bit code number that identifies the device derivative. For example, the first revision of the
MC9S08GB60 version of the HSC08 Family has a code number of SDIDH:SDIDL = $0 002). This
identification code allows an external development host to associate a register definition file to a particular
target MCU so the debugger understands where registers and control bits are located in the target MCU.
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Development Support
7.2 Features
Features of the background debug controller (BDC) include:
• Single dedicated pin for mode selection and background communications
• BDC registers not located in 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 BDM enabled
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) 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)
7.3 Background Debug Controller (BDC)
All MCUs in the HCS08 Family contain a single-wire background debug interface which supports in-circuit
programming of on-chip non-volatile 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. The single BKGD interface pin is a separate dedicated pin which is not accessible to user
programs.
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Background Debug Controller (BDC)
BDM 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). The BACKGROUND command causes the target MCU to enter
active background mode. 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 (BDC).
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 RS232 serial port, a parallel printer port,
or some other type of communications such as Ethernet or 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 (if there is a reset pin), and sometimes a VDD signal. 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 non-volatile memory has been programmed. VDD can
sometimes be used to allow the pod to take power from the target system to avoid the need for a separate
power supply.
7.3.1 BKGD Pin Description
All commands and bidirectional data for the background debug system are communicated through the
BKGD pin.
BKGD is the single-wire background debug interface pin. The primary function of this pin is for
bidirectional serial communication of background debug commands and data. During reset, this pin
selects between starting in active background mode and 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.
Figure 7-1 shows the standard header for connection of a BDM pod. A pod is a small interface device that
connects a host computer such as a personal computer to a target HCS08 system. BKGD and GND are
the minimum connections required to communicate with a target MCU. The open-drain RESET signal is
included in the connector to allow a direct way for the host to force a target system reset. By controlling
both BKGD and RESET, the host also can force the target system to reset into active background mode
rather than start the user application program. (This is useful to gain control of a target MCU whose
FLASH program memory has not been programmed yet with a user application program.) The VDD
connection can sometimes allow a host debugger pod to take power from the target system rather than
using a separate power source for the pod. 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 7-1. Standard BDM Tool Connector
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Development Support
In cases where there is no RESET pin on the MCU or no RESET connection from the debug pod to the
target MCU, there are other ways to force a target system reset:
• Write a logic 1 to the BDM force reset (BDFR) bit in the SBDFR register. This bit can only be written
using a serial WRITE_BYTE or WRITE_BYTE_WS command.
• Turn power off and back on to force a power-on reset.
• Point the PC at an illegal opcode and use GO or TRACE1 to force an illegal opcode reset.
BKGD is a pseudo-open-drain pin with an on-chip pullup so no external pullup resistor is required
(although some users still use an external pullup resistor to improve noise immunity). Unlike typical
open-drain pins, the external resistor capacitor (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 7.3.2 Communication Details for more detail.
When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD
chooses the normal operating mode. When a pod 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. Of course, it is not necessary to force a reset to communicate with the target MCU through the
background debug interface. In fact, you can even connect a powered debug pod onto a running target
system without disturbing the running application program.
Background debug controller (BDC) serial communications use a custom serial protocol that was first
introduced on the M68HC12 Family of microcontrollers. This protocol assumes that the host knows the
communication clock rate which is determined by the target BDC clock rate. The BDC clock rate may be
the system bus clock frequency or an alternate frequency source depending on the state of the CLKSW
control bit in the BDCSCR register. On the MC9S08GB60, the alternate frequency source is a self-clocked
local oscillator (ICGLCLK) in the BDC that runs about 8 MHz independent of the bus frequency. On some
other HCS08 derivatives, the alternate frequency source could be the undivided crystal frequency. All
communication is initiated and controlled by the host which drives a high-to-low edge to signal the
beginning of each bit time. Commands and data are sent most significant bit first (MSB-first).
If a host is attempting to communicate with a target MCU which 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. After establishing communications, the host can read
the BDC status and control register and write to the clock switch (CLKSW) control bit to change the source
of the BDC clock for further BDC communications if necessary.
7.3.2 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.
Refer to 7.3.2.1 BDC Communication Speed Considerations for more detailed information about the
source of the BDC communications clock.
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7.3.2.1 BDC Communication Speed Considerations
The custom serial protocol requires the debug pod to know the target BDC communication clock speed.
There are two possible sources for this clock frequency (as selected by the CLKSW bit in the BDCSCR
register), the bus rate clock or a fixed-frequency alternate clock source that may be different for different
HCS08 derivatives. In an MC9S08GB60, this alternate clock source is a self-clocked local oscillator in the
BDC module that runs about 8 MHz (independent of the CPU bus frequency). In other HCS08 devices
this alternate clock source is the undivided crystal frequency. Future derivatives may use some other
source for this alternate clock. Refer to the data sheet for each HCS08 derivative for information about
the alternate clock source in the device you are using.
When the MCU is reset in normal user mode, CLKSW is reset to 0 which selects the alternate clock
source. This clock source is a fixed frequency that is independent of the bus frequency so it will not
change if a user program modifies clock generator settings. This is the preferred clock source for general
debugging.
When the MCU is reset in active background mode, CLKSW is reset to 1 which selects the bus clock as
the source of the BDC clock. This CLKSW setting is most commonly used during FLASH memory
programming because the bus clock can usually be configured to operate at the highest allowed bus
frequency which will ensure the fastest possible FLASH programming times. Since the host system is in
control of changes to clock generator settings, it can know when a different BDC communication speed
should be used. The host programmer also knows that no unexpected change in bus frequency could
occur to disrupt BDC communications.
Normally, the CLKSW = 1 option should not be used for general debugging because there is no way to
be sure the user’s application program with not change the clock generator settings. This is especially
true in the case of application programs that are not yet fully debugged.
After any reset (or at any other time), the host system can issue a SYNC command to determine the speed
of the BDC clock. CLKSW may be written using a serial WRITE_CONTROL command through the BDC
interface. CLKSW is located in the BDCSCR register in the BDC module and it is not accessible in the
normal memory map of the MCU. This means that no user program can modify this register (intentionally
or unintentionally).
7.3.2.2 Bit Timing Details
The BKGD pin can receive a high or low level or transmit a high or low logic 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.
Figure 7-2 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. Since the target does not drive
the BKGD pin during this period, there is no need to treat the line as an open-drain signal during
host-to-target transmissions.
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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 7-2. BDC Host-to-Target Serial Bit Timing
Figure 7-3 shows the host receiving a logic 1 from the target MCU. Since 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
TARGET MCU
SPEEDUP PULSE
HIGH IMPEDANCE
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 7-3. BDC Target-to-Host Serial Bit Timing (Logic 1)
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Background Debug Controller (BDC)
Figure 7-4 shows the host receiving a logic 0 from the target MCU. Since 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.
Since 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
SPEEDUP PULSE
PERCEIVED START
OF BIT TIME
BKGD PIN
10 CYCLES
10 CYCLES
EARLIEST START
OF NEXT BIT
HOST SAMPLES BKGD PIN
Figure 7-4. BDM Target-to-Host Serial Bit Timing (Logic 0)
7.3.3 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 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; however, this bit should not be
written to 1 if the target MCU has an FLL or PLL and user software might change the FLL/PLL settings
while debugging is taking place. Changing FLL/PLL settings while CLKSW = 1 causes BDC
communications to fail because the host cannot predict the correct communications speed.
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7.3.3.1 BDC Status and Control Register
This register can be read or written by serial BDC commands but is not accessible to user programs
because it is not located in the normal memory map of the MCU.
Bit 7
Read:
Write:
6
ENBDM
BDMACT
5
4
3
BKPTEN
RTS
CLKSW
2
1
Bit 0
WS
WSF
DVF
Normal Reset:
0
0
0
0
0
0
0
0
Reset in active background mode:
1
0
0
0
1
0
0
0
= Unimplemented or Reserved
Figure 7-5. BDC Status and Control Register (BDCSCR)
ENBDM — Enable BDM (permit active background debug 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
BKPTEN — BDC Breakpoint Enable
If this bit is clear, the BDC breakpoint is disabled and the FTS 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 the 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.
CLKSW — Select Source for BDC Communications Clock
When the MCU is reset in normal user mode, CLKSW is forced to 0 which selects the fixed alternate
frequency source as the BDC clock. In the MC9S08GB60, the alternate frequency source is a local
oscillator in the BDC module that runs about 8 MHz. When the MCU is reset in active background
mode, CLKSW is forced to 1 which selects the bus clock at the BDC clock. You should avoid using the
CLKSW = 1 option while running a user program that might change the bus frequency unexpectedly
because this could result in loss of BDC communications.
1 = CPU bus clock
0 = Derivative-specific fixed alternate frequency source
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Background Debug Controller (BDC)
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 mode 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 mode to active background mode.
0 = Target CPU is running user application code or is 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 and into active background mode, repeat the command that
failed, then return to the user program. (If desired, the host can 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 set if a memory access command failed due to the target CPU executing a slow
memory access at or about the same time. The usual recovery strategy is to issue READ_LAST
commands until the returned status information indicated the original access completed successfully.
Since no current HCS08 devices have memory modules that support slow accesses, this bit should
always read 0. Consult the data sheet for a specific HCS08 device if you are uncertain about whether
it includes any slow memory modules.
1 = Memory access command failed because the CPU was not finished with a slow memory access.
0 = Memory access did not conflict with a slow memory access.
7.3.3.2 BDC Breakpoint Match Register
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.
Breakpoints are normally set while the target MCU is in active background mode before running the user
application program. However, since READ_BKPT and WRITE_BKPT are non-intrusive commands, they
could be executed even while the user program is running. For additional information about setup and use
of the hardware breakpoint logic in the BDC, refer to 7.3.7 BDC Hardware Breakpoint.
7.3.4 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 7-1 shows all HCS08 BDC commands, a shorthand description of their coding structure, and the
meaning of each command. Subsequent paragraphs describe each command in greater detail.
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Table 7-1. BDC Command Summary
Command
Mnemonic
Active Background
Mode/
Non-Intrusive
Coding
Structure(1)
Description
SYNC
Non-intrusive
n/a(2)
Request a timed reference pulse to determine
target BDC communication speed
ACK_ENABLE
Non-intrusive
D5/d
Enable handshake. Issues an ACK pulse after
the command is executed.
ACK_DISABLE
Non-intrusive
D6/d
Disable handshake. This command does not
issue an ACK pulse.
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 Background
Mode
08/d
Go to execute the user application program
starting at the address currently in the PC
TRACE1
Active Background
Mode
10/d
Trace 1 user instruction at the address in the
PC, then return to active background mode
TAGGO
Active Background
Mode
18/d
Same as GO but enable external tagging
(HCS08 devices have no external tagging pin,
so TAGGO is just like GO in an HCS08)
READ_A
Active Background
Mode
68/d/RD
Read accumulator (A)
READ_CCR
Active Background
Mode
69/d/RD
Read condition code register (CCR)
READ_PC
Active Background
Mode
6B/d/RD16
Read program counter (PC)
READ_HX
Active Background
Mode
6C/d/RD16
Read H and X register pair (H:X)
READ_SP
Active Background
Mode
6F/d/RD16
Read stack pointer (SP)
READ_NEXT
Active Background
Mode
70/d/RD
Increment H:X by one, then read memory byte
located at H:X
READ_NEXT_WS
Active Background
Mode
71/d/SS/RD
Increment H:X by one, then read memory byte
located at H:X. Report status and data.
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Table 7-1. BDC Command Summary (Continued)
Command
Mnemonic
Active Background
Mode/
Non-Intrusive
Coding
Structure(1)
Description
WRITE_A
Active Background
Mode
48/WD/d
Write accumulator (A)
WRITE_CCR
Active Background
Mode
49/WD/d
Write condition code register (CCR)
WRITE_PC
Active Background
Mode
4B/WD16/d
Write program counter (PC)
WRITE_HX
Active Background
Mode
4C/WD16/d
Write H and X register pair (H:X)
WRITE_SP
Active Background
Mode
4F/WD16/d
Write stack pointer (SP)
WRITE_NEXT
Active Background
Mode
50/WD/d
Increment H:X by one, then write memory byte
located at H:X
WRITE_NEXT_WS
Active Background
Mode
51/WD/d/SS
Increment H:X by one, then write memory byte
located at H:X. Also report status.
1. Key:
Commands begin with an 8-bit hexadecimal command code in the host-to-target direction (MSB first)
/ — separates parts of the command
d — delay 16 target BDC clock cycles (the CLKSW bit in BDCSCR controls the source of the BDC clock)
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 — 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)
2. The SYNC command is a special operation which does not have a command code.
7.3.4.1 SYNC — Request Timed Reference Pulse
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 (Bus rate clock
or derivative-specific alternate clock source)
• Drives BKGD high for a brief speedup pulse to get a fast rise time (This speedup pulse is typically
one cycle of the host clock which is as fast as the fastest possible target BDC clock.)
• Removes all drive to the BKGD pin so it reverts to high impedance
• Listens to the BKGD pin for the sync response pulse
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Upon detecting the sync request from the host (which is a much longer low time than would ever occur
during normal BDC communications), the target:
• 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.
7.3.4.2 ACK_ENABLE
Enable Host/Target handshake protocol
Non-intrusive
$D5
host -> target
D
L
Y
Enables the hardware handshake protocol in the serial communication. The hardware handshake is
implemented by an acknowledge (ACK) pulse issued by the target MCU in response to a host command.
The ACK_ENABLE command is interpreted and executed in the BDC block without the need to interface
with the CPU. However, an acknowledge (ACK) pulse will be issued by the target device after this
command is executed. This feature could be used by the host in order to evaluate if the target supports
the hardware handshake protocol. If the target supports the hardware handshake protocol the
subsequent commands are enabled to execute the hardware handshake protocol, otherwise this
command is ignored by the target.
For additional information about the hardware handshake protocol, refer to 7.3.5 Serial Interface
Hardware Handshake Protocol and 7.3.6 Hardware Handshake Abort Procedure.
7.3.4.3 ACK_DISABLE
Disable Host/Target handshake protocol
Non-intrusive
$D6
host -> target
D
L
Y
Disables the serial communication handshake protocol. The subsequent commands, issued after the
ACK_DISABLE command, will not execute the hardware handshake protocol. This command will not be
followed by an ACK pulse.
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Background Debug Controller (BDC)
7.3.4.4 BACKGROUND
Enter Active Background Mode (if Enabled)
Non-intrusive
$90
pod → target
D
L
Y
Provided the ENBDM control bit in the BDCSCR is 1 (BDM enabled), the BACKGROUND command
causes the target MCU to enter active background mode as soon as the current CPU instruction finishes.
If ENBDM is 0 (its default value), the BACKGROUND command is ignored.
A delay of 16 BDC clock cycles is required after the BACKGROUND command to allow the target MCU
to finish its current CPU instruction and enter active background mode before a new BDC command can
be accepted.
After the target MCU is reset into a normal operating mode, the host debugger would send a
WRITE_CONTROL command to enable the active background mode before attempting to send the
BACKGROUND command the first time. Normally, the development host would set ENBDM once at the
beginning of a debug session or after a target system reset, and then leave the ENBDM bit set during
debugging operations. During debugging, the host would use GO and TRACE1 commands to move from
active background mode to normal user program execution and would use BACKGROUND commands
or breakpoints to return to active background mode.
7.3.4.5 READ_STATUS
Read Status from BDCSCR
Non-intrusive
$E4
Read BDCSCR
pod → target
target → pod
This command allows a host to read the contents of the BDC status and control register (BDCSCR). This
register is not in the memory map of the target MCU, rather it is built into the BDC logic and is accessible
only through READ_STATUS and WRITE_CONTROL serial BDC commands.
The most common use for this command is to allow the host to determine whether the target MCU is
executing normal user program instructions or if it is in active background mode. For example, during a
typical debug session, the host might set breakpoints in the user’s program and then use a GO command
to begin normal user program execution. The host would then periodically execute READ_STATUS
commands to tell when a breakpoint has been encountered and the target processor has gone into active
background mode. Once the target has entered active background mode, the host would read the
contents of target CPU registers.
READ_STATUS is also used to tell when a BDC memory write command completes after a DVF failure
due to a slow memory access. If a WRITE_BYTE_WS or WRITE_NEXT_WS command indicates a failure
due to a slow memory access (DVF = 1), the host should execute READ_STATUS commands until the
status response indicates the write access has completed. The write request is latched during the
WRITE_BYTE_WS or WRITE_NEXT_WS so there is no need to repeat the write command; just wait for
status to indicate the latched request has completed.
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READ_STATUS might also be used to check whether the target MCU has gone into wait or stop mode.
During a debug session, the host or user may decide it has taken too long to reach a breakpoint in the
user program. The host could then issue a READ_STATUS command and check the WS status bit to see
if the target MCU is still running user code or if it has entered wait or stop mode. If WS = 0 and
BDMACT = 0, meaning it is running user code and is not in wait or stop, the host might choose to issue
a BACKGROUND command to stop the user program and enter active background mode where the host
can check the CPU registers and find out what the target program is doing.
7.3.4.6 WRITE_CONTROL
Write Control Bits in BDCSCR
Non-intrusive
$C4
Write BDCSCR
pod → target
pod → target
This command is used to enable active background mode, choose the clock source for BDC
communications, and control the hardware breakpoint logic in the BDC by writing to control bits in the
BDC status and control register (BDCSCR). This register is not in the memory map of the target MCU,
rather it is built into the BDC logic and is only accessible through READ_STATUS and WRITE_CONTROL
serial BDC commands. Some bits in BDCSCR have write restrictions such as the status bits BDMACT,
WS, WSF, and DVF which are read-only status indicators, and ENBDM which cannot be cleared while
BDM is active.
The ENBDM control bit defaults to 0 (active background mode not allowed) when the target MCU is reset
in normal operating mode. WRITE_CONTROL is used to enable the active background mode. This is
normally done once and ENBDM is left on throughout the debug session. However, the debug system
may want to change ENBDM to 0 measure true stop current in the target system (because ENBDM = 1
prevents the clock generation circuitry from disabling the internal clock oscillator or crystal oscillator when
the CPU executes a STOP instruction).
The breakpoint enable (BKPTEN) and force/tag select (FTS) control bits are used to control the hardware
breakpoint logic in the BDC. This is a single breakpoint that compares the current 16-bit CPU address
against the value in the BDCBKPT register. A WRITE_CONTROL command is used to change BKPTEN
and FTS, and a WRITE_BKPT command is used to write the 16-bit BDCBKPT address match register.
The CLKSW bit in BDCSCR determines the source of the clock used for BDC communications. If
CLKSW = 0 (user mode default), the clock that drives the BDC is the alternate fixed-frequency source.
The details of the exact clock source for the BDC in these cases depends on what clock generation
circuitry is present in the particular HCS08 derivative MCU. For the MC9S08GB60, when CLKSW = 0, the
BDC clock source is a local oscillator in the BDC module (about 8 MHz).
When CLKSW = 1, the CPU bus frequency is used as the clock source to drive BDC communications
logic. The CPU bus frequency may be a crystal or an FLL or derived from a PLL. CLKSW should not be
set to 1 if the application is using an FLL or PLL and is changing the bus frequency in user programs,
because BDC communications require that the host knows the target BDC communications speed and
the host has no way to know if/when a user program might change the clock generator settings.
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Background Debug Controller (BDC)
7.3.4.7 READ_BYTE
Read Data from Target Memory Location
$E0
ADDRESS(16)
pod → target
pod → target
Non-intrusive
Read DATA(8)
D
L
Y
target → pod
This command is used to read the contents of a memory location in the target MCU without checking the
BDC status to be sure the data is valid. In systems which have no slow memory accesses, and the target
is currently in active background mode or is known to be executing a program which has no STOP or
WAIT instructions, READ_BYTE is faster than the more general READ_BYTE_WS which reports status
in addition to returning the requested read data. The most significant use of the READ_BYTE command
is during in-circuit FLASH programming where the host downloads data to be programmed at the same
time the target CPU is executing the code that actually programs the FLASH memory. Since the host
provides the FLASH programming code, it can guarantee that there are no STOP or WAIT instructions.
In general-purpose user programs and especially in programs that have not been debugged, STOP or
WAIT instructions and slow memory accesses can occur at any time. To avoid the possibility of invalid
read operations, the host should use the READ_BYTE_WS command instead of READ_BYTE to check
the status to be sure the read has returned valid data. If the status indicates the read was not valid, the
host can execute READ_LAST commands until the status indicates the returned data is valid.
7.3.4.8 READ_BYTE_WS
Read Data from Target and Report Status
$E1
ADDRESS(16)
pod → target
pod → target
Non-intrusive
D
L
Y
Read BDCSCR
Read DATA(8)
target → pod
target → pod
This is the command normally used by a host debug system to perform general-purpose memory read
operations. In addition to returning the data from the requested target memory location, this command
returns the contents of the BDC status and control register. The status information can be used to
determine whether the data that was returned is valid or not. If a slow memory access was in progress at
the time of the read, the data valid failure (DVF) status bit will be 1. If the target MCU was just entering
wait or stop mode at the time of the read, the wait/stop failure (WSF) status bit will be 1. If DVF and WSF
are both 0, the data that was returned is valid.
In the case of a DVF error, execute READ_LAST commands until the status response indicates the data
is correct. In the case of a WSF error, first issue a BACKGROUND command to wake the target CPU from
wait or stop and enter active background mode. From there, issue a new READ_BYTE or
READ_BYTE_WS command, and if desired adjust the program counter (PC) and stack and re-execute
the WAIT or STOP instruction to return the target to wait or stop mode.
If you are sure that the target system has no slow accesses and will not execute a WAIT or STOP
instruction during the memory access, use the faster READ_BYTE command instead of
READ_BYTE_WS. In user programs that have not been debugged, there is no guarantee that the CPU
will not run away and execute an unintended WAIT or STOP instruction.
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7.3.4.9 READ_LAST
Re-Read from Last Address with Status
Non-intrusive
$E8
Read BDCSCR
Read DATA(8)
pod → target
target → pod
target → pod
This command is used only after a READ_BYTE_WS command where the DVF status bit indicated an
error. In that case, issue READ_LAST commands until the status bits indicate a valid response. The
READ_LAST command uses the memory address from the previous READ_BYTE_WS command so the
command is shorter and faster than other read commands.
7.3.4.10 WRITE_BYTE
Write Data to Target Memory Location
Non-intrusive
$C0
ADDRESS(16)
Write DATA(8)
pod → target
pod → target
pod → target
D
L
Y
This command is used to write the contents of a memory location in the target MCU without checking the
BDC status to be sure the write was completed successfully. In systems which have no slow memory
accesses, and the target is currently in active background mode or is known to be executing a program
which has no STOP or WAIT instructions, WRITE_BYTE is faster than the more general
WRITE_BYTE_WS which reports status in addition to performing the requested write operation. The most
significant use of the WRITE_BYTE command is during in-circuit FLASH programming where the host
downloads data to be programmed at the same time the target CPU is executing the code that actually
programs the FLASH memory. Since the host provides the FLASH programming code, it can guarantee
that there are no STOP or WAIT instructions.
In general-purpose user programs and especially in programs that have not been debugged, STOP or
WAIT instructions and slow memory accesses can occur at any time. To avoid the possibility of invalid
write operations, the host should use the WRITE_BYTE_WS command instead of WRITE_BYTE to check
the status to be sure the write was completed successfully.
7.3.4.11 WRITE_BYTE_WS
Write Data to Target and Report Status
$C1
pod → target
Non-intrusive
ADDRESS(16)
pod → target
Write DATA(8)
pod → target
Read BDCSCR
D
L
Y
target → pod
This is the command normally used by a host debug system to perform general-purpose memory write
operations. In addition to performing the requested write to a target memory location, this command
returns the contents of the BDC status and control register. The status information can be used to tell if
the write operation was completed successfully. If a slow memory access was in progress at the time of
the write, the data valid failure (DVF) status bit will be 1. If the target MCU was just entering wait or stop
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mode at the time of the read, the wait/stop failure (WSF) status bit will be 1 and the write command is
cancelled. If DVF and WSF are both 0, the write operation was completed successfully.
If DVF is set in the returned status value, the write was not completed (although the address and data for
the operation are latched). Do READ_STATUS commands until DVF is returned as a 1 to indicate that
the write operation was completed successfully. If the WSF bit indicated a WAIT or STOP instruction
caused the write operation to fail, do a BACKGROUND command to force the target system out of wait
or stop mode and into active background mode. From there, repeat the failed write operation, and if
desired adjust the PC and stack and re-execute the WAIT or STOP instruction to return the target to wait
or stop mode.
If you are sure that the target system has no slow accesses and will not execute a WAIT or STOP
instruction during the memory access, you can use the faster WRITE_BYTE command instead of
WRITE_BYTE_WS. In user programs that have not been debugged, there is no guarantee that the CPU
will not run away and execute an unintended WAIT or STOP instruction.
7.3.4.12 READ_BKPT
Read 16-Bit BDC Breakpoint Register (BDCBKPT)
$E2
Read data from BDCBKPT register
pod → target
target → pod
Non-intrusive
This command is used to read the 16-bit BDCBKPT address match register in the hardware breakpoint
logic in the BDC.
7.3.4.13 WRITE_BKPT
Write 16-Bit BDC Breakpoint Register (BDCBKPT)
$C2
Write data to BDCBKPT register
pod → target
pod → target
Non-intrusive
This command is used to write a 16-bit address value into the BDCBKPT register in the BDC. This
establishes the address of a breakpoint. The BKPTEN bit in the BDCSCR determines whether the
breakpoint is enabled. If BKPTEN = 1 and the FTS control bit in the BDCSCR is set (force), a successful
match between the CPU address and the value in the BDCBKPT register will force a transition to active
background mode at the next instruction boundary. If BKPTEN = 1 and FTS = 0, the opcode at the
address specified in the BDCBKPT register will be tagged as it is fetched into the instruction queue. If and
when a tagged opcode reaches the top of the instruction queue and is about to be executed, the MCU will
enter active background mode rather than execute the tagged instruction.
In normal debugging environments, breakpoints are established while the target MCU is in active
background mode before going to the user’s program. However, since this is a non-intrusive command,
it could be executed even when the MCU is running a user application program. BDC serial
communications are essentially asynchronous to a running user program, so it is impractical to predict the
exact time of a BDCBKPT register value change relative to a particular bus cycle of the user’s program
when the WRITE_BKPT instruction is executed while the user application program is running.
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7.3.4.14 GO
Start Execution of User Program Starting at Current PC
Active Background
Mode
$08
pod → target
D
L
Y
This command is used to exit the active background mode and begin execution of user program
instructions starting at the address in the PC. Typically, the host debug monitor program modifies the PC
value (using a WRITE_PC command) before issuing a GO command to go to an arbitrary point in the user
program. This WRITE_PC command is not needed if the host simply wants to continue the user program
where it left off when it entered active background mode.
7.3.4.15 TRACE1
Run One User Instruction Starting at the Current PC
Active Background
Mode
$10
pod → target
D
L
Y
This command is used to run one user instruction and return to active background mode. The address in
the PC determines what user instruction will be executed, and the PC value after TRACE1 is completed
will reflect the results of the executed instruction.
7.3.4.16 TAGGO
Enable External Tagging and Start Execution of User Program
Active Background
Mode
$18
pod → target
D
L
Y
This instruction enables the external tagging function and goes to the user program starting at the address
currently in the PC. However, since HCS08 devices do not have an external pin connected to the tagging
input of the BDC module, this command is essentially the same as the GO command, so there is no need
to use TAGGO commands in an HCS08 system.
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7.3.4.17 READ_A
Active Background
Mode
Read Accumulator A of the Target CPU
$68
pod → target
Accum. data(8)
D
L
Y
target → pod
Read the contents of the accumulator (A) of the target CPU. Since the CPU in the target MCU is effectively
halted while the target is in active background mode, there is no need to save the target CPU registers
on entry into active background mode and no need to restore them on exit from active background to a
user program.
7.3.4.18 READ_CCR
Read the Condition Code Register of the Target CPU
$69
pod → target
Active Background
Mode
CCR data(8)
D
L
Y
target → pod
Read the contents of the condition code register (CCR) of the target CPU. Since the CPU in the target
MCU is effectively halted while the target is in active background mode, there is no need to save the target
CPU registers on entry into active background mode and no need to restore them on exit from active
background mode to a user program. The CCR value is not affected by BDC commands (except, of
course, the WRITE_CCR command).
7.3.4.19 READ_PC
Read the Program Counter of the Target CPU
$6B
pod → target
Active Background
Mode
Program Counter data(16)
D
L
Y
target → pod
Read the contents of the program counter (PC) of the target CPU. Since the CPU in the target MCU is
effectively halted while the target is in active background mode, there is no need to save the target CPU
registers on entry into active background mode and no need to restore them on exit from active
background mode to a user program.
The value in the PC when the target MCU enters active background mode is the address of the instruction
that would have executed next if the MCU had not entered active background mode. If the target CPU
was in wait or stop mode when a BACKGROUND command caused it to go to active background mode,
the PC will hold the address of the instruction after the WAIT or STOP instruction that was responsible for
the target CPU being in wait or stop, and the WS bit will be set. In the boundary case (where an interrupt
and a BACKGROUND command arrived at about the same time and the interrupt was responsible for the
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target CPU leaving wait or stop and then the BACKGROUND command took effect), the WS bit will be
clear and the PC will be pointing at the first instruction in the interrupt service routine. In the case of a
software breakpoint (where the host placed a BGND opcode at the desired breakpoint address), the PC
will be pointing at the address immediately following the inserted BGND opcode, and the host monitor will
adjust the PC backward by one after removing the software breakpoint.
7.3.4.20 READ_HX
Read the H:X Register Pair of the Target CPU
$6C
pod → target
Active Background
Mode
H:X register pair data(16)
D
L
Y
target -> pod
Read the contents of the H:X register pair (H:X) of the target CPU. Since the CPU in the target MCU is
effectively halted while the target is in active background mode, there is no need to save the target CPU
registers on entry into active background mode and no need to restore them on exit from active
background mode to a user program. H and X can be read only as a 16-bit register pair. (There are no
BDC commands to read H and X separately.)
7.3.4.21 READ_SP
Active Background
Mode
Read the Stack Pointer of the Target CPU
$6F
pod → target
Stack Pointer data(16)
D
L
Y
target → pod
Read the contents of the stack pointer (SP) of the target CPU. Since the CPU in the target MCU is
effectively halted while the target is in active background mode, there is no need to save the target CPU
registers on entry into active background mode and no need to restore them on exit from active
background mode to a user program.
7.3.4.22 READ_NEXT
Increment H:X, Then Read Memory Pointed to by H:X
$70
pod → target
Active Background
Mode
Memory data(8)
D
L
Y
target → pod
READ_NEXT increments the H:X register pair by one, then reads the memory location pointed to by the
incremented 16-bit H:X register pair. This command is similar to the READ_BYTE command except that
it uses the value in the H:X index register pair as the address for the operation. There is no address
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included in this command, so it is more efficient than the READ_BYTE command. Since READ_NEXT
uses the H:X register pair of the CPU, it is an active background mode command while READ_BYTE is
a non-intrusive command.
Typically, the host debug system would save the contents of H:X, set H:X to one less than the address of
the first byte of a block to be read, execute READ_NEXT commands to read a block of memory, then
restore the original contents of H:X (if necessary).
Since READ_NEXT is an active background mode command, there is no concern about errors due to
WAIT or STOP instructions and no concern about unexpected slow memory accesses from user code.
There could still be slow memory accesses due to the READ_NEXT command itself attempting to access
a slow memory location; however, this is completely predictable by the host debug system. In the unusual
case of a system that has slow memory and the READ_NEXT operation needs to access memory
locations that are slow, use the READ_NEXT_WS command rather than READ_NEXT.
7.3.4.23 READ_NEXT_WS
Increment H:X, Then Read Memory @ H:X and Report Status
$71
pod → target
D
L
Y
Read BDCSCR
Read DATA(8)
target → pod
target → pod
Active Background
Mode
READ_NEXT_WS increments the H:X register pair by one, reads the memory location pointed to by the
incremented 16-bit H:X register pair, and returns both the contents of the BDC status and control register
(BDCSCR) and the 8-bit data. This command is similar to the READ_NEXT command except that it
returns the status from BDCSCR in addition to performing the requested read operation. This status
information can be used to tell if the requested read operation returned valid data (DVF = 0). If the status
indicates an access failed because it is a slow memory location, execute READ_LAST_WS commands
until the status indicates the read data is valid. (Normally, this would require only one READ_LAST_WS
command since the BDC serial commands are much slower than the target bus speed.)
7.3.4.24 WRITE_A
Active Background
Mode
Write Accumulator A of the Target CPU
$48
Accum. data(8)
pod → target
pod → target
D
L
Y
Write new data to the accumulator (A) of the target CPU. This command can be used to change the value
in the accumulator before returning to the user application program via a GO or TRACE1 command.
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7.3.4.25 WRITE_CCR
Active Background
Mode
Write the Condition Code Register of the Target CPU
$49
CCR data(8)
pod → target
pod → target
D
L
Y
Write new data to the condition code register (CCR) of the target CPU. This command can be used to
change the condition codes before returning to the user application program via a GO or TRACE1
command. Other BDC commands do not alter the states of any condition code bits.
7.3.4.26 WRITE_PC
Active Background
Mode
Write the Program Counter of the Target CPU
$4B
Program Counter data(16)
pod → target
pod → target
D
L
Y
This command is used to change the contents of the program counter (PC) of the target CPU before
returning to the user application program via a GO or TRACE1 command.
7.3.4.27 WRITE_HX
Active Background
Mode
Write the H:X Register Pair of the Target CPU
$4C
H:X register pair data(16)
pod → target
pod → target
D
L
Y
Write new data to the H:X index register pair (H:X) of the target CPU. This command can be used to
change the value in the 16-bit index register pair (H:X) before returning to the user application program
via a GO or TRACE1 command.
7.3.4.28 WRITE_SP
Active Background
Mode
Write the Stack Pointer of the Target CPU
$4F
Stack Pointer data(16)
pod → target
pod → target
D
L
Y
Write new data to the stack pointer (SP) of the target CPU. This command can be used to change the
value in the stack pointer before returning to the user application program via a GO or TRACE1 command.
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7.3.4.29 WRITE_NEXT
Increment H:X, Then Write Memory Pointed to by H:X
$50
Memory data(8)
pod → target
pod → target
Active Background
Mode
D
L
Y
WRITE_NEXT increments the H:X register pair by one, then writes to the memory location pointed to by
the incremented 16-bit H:X register pair. This command is similar to the WRITE_BYTE command except
that it uses the value in the H:X index register pair as the address for the operation. Because no address
is included in this command, it is more efficient than the WRITE_BYTE command. Since WRITE_NEXT
uses the H:X register pair of the CPU, it is an active background mode command while WRITE_BYTE is
a non-intrusive command.
Typically, the host debug system would save the contents of H:X, set H:X to one less than the address of
the first byte of a block to be written, execute WRITE_NEXT commands to write a block of memory, then
restore the original contents of H:X, if necessary.
Since WRITE_NEXT is an active background mode command, there is no concern about errors due to
WAIT or STOP instructions and no concern about unexpected slow memory accesses from user code.
There could still be slow memory accesses due to the WRITE_NEXT command itself attempting to access
a slow memory location; however, this is completely predictable by the host debug system. In the unusual
case of a system that has slow memory and the WRITE_NEXT operation needs to access memory
locations that are slow, use the WRITE_NEXT_WS command rather than WRITE_NEXT.
7.3.4.30 WRITE_NEXT_WS
Increment H:X, Then Write Memory @ H:X and Report Status
$51
Memory data(8)
pod → target
pod → target
Active Background
Mode
Read BDCSCR
D
L
Y
target → pod
WRITE_NEXT_WS increments the H:X register pair by one, writes to the memory location pointed to by
the incremented 16-bit H:X register pair, attempts to perform the requested write operation, and returns
the contents of the BDC status and control register (BDCSCR). This command is similar to the
WRITE_NEXT command except that it returns the status from BDCSCR in addition to performing the
requested write operation. This status information can be used to tell if the requested write operation was
completed successfully (DVF=0). If the status indicates an access failed because it is a slow memory
location, the address and data for the operation are latched and you should execute READ_STATUS
commands until the status indicates the write was completed successfully. (This would normally only
require one READ_STATUS command since the BDC serial commands are much slower than the target
bus speed.)
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7.3.5 Serial Interface Hardware Handshake Protocol
BDC commands that require CPU execution are ultimately treated at the MCU bus rate. Since the BDC
clock source can be asynchronous relative to the bus frequency, when CLKSW = 0, it is necessary to
provide a handshake protocol in which the host could determine when an issued command is executed
by the CPU. This sub-section will describe the hardware handshake protocol.
The hardware handshake protocol signals to the host controller when an issued command was
successfully executed by the target. This protocol is implemented by a low pulse (16 BDC clock cycles)
followed by a brief speedup pulse on the BKGD pin, generated by the target MCU when a command,
issued by the host, has been successfully executed. See Figure 7-6. This pulse is referred to as the ACK
pulse. After the ACK pulse is finished, the host can start the data-read portion of the command if the last
issued command was a read command, or start a new command if the last command was a write
command or a control command (BACKGROUND, GO, GO_UNTIL or TRACE1). The ACK pulse is not
issued earlier than 32 BDC clock cycles after the BDC command was issued. The end of the BDC
command is assumed to be the 16th BDC clock cycle of the last bit. This minimum delay assures enough
time for the host to recognize the ACK pulse. Note also that there is no upper limit for the delay between
the command and the related ACK pulse, since the command execution depends on the CPU bus
frequency, which in some cases could be very slow compared to the serial communication rate. This
protocol allows great flexibility for pod designers, since it does not rely on any accurate time measurement
or short response time to any event in the serial communication.
BDC CLOCK
(TARGET MCU)
HIGH-IMPEDANCE
TARGET
TRANSMITS
ACK PULSE
16 CYCLES
32 CYCLES
HIGH-IMPEDANCE
SPEED UP PULSE
MINIMUM DELAY
FROM THE BDC COMMAND
BKGD PIN
EARLIEST
START OF
NEXT BIT
16th CYCLE OF THE
LAST COMMAD BIT
Figure 7-6. Target Acknowledge Pulse (ACK)
NOTE
If the ACK pulse was issued by the target, the host assumes the previous
command was executed. If the CPU enters WAIT or STOP prior to
executing a non-intrusive command, the ACK pulse will not be issued,
meaning that the BDC command was not executed. After entering WAIT or
STOP mode, the BDC command is no longer pending and the DVF status
bit is kept one until the next command is successfully executed.
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Figure 7-7 shows the ACK handshake protocol in a command level timing diagram. The READ_BYTE
command is used as an example. First, the 8-bit command code is sent by the host, followed by the
address of the memory location to be read. The target BDC decodes the command and sends it to the
CPU. Upon receiving the BDC command request, the CPU completes the current instruction being
executed, the CPU is temporarily halted, the BDC executes the READ_BYTE command and then the
CPU continues. This process is referred to as cycle stealing. The READ_BYTE command takes two bus
cycles in order to be executed by the CPU. After that, the CPU notifies to the BDC that the requested
command was done and then resumes the normal flow of the application program. After detecting the
READ_BYTE command is done, the BDC issues an ACK pulse to the host controller, indicating that the
addressed byte is ready to be retrieved. After detecting the ACK pulse, the host initiates the data-read
portion of the command.
TARGET
BKGD PIN
READ_BYTE
BYTE ADDRESS
HOST
HOST
BYTE IS
RETRIEVED
TARGET
NEW BDC COMMAND
HOST
TARGET
BDC ISSUES THE
ACK PULSE (NOT TO SCALE)
BDC DECODES
THE COMMAND
CPU EXECUTES THE
READ_BYTE
COMMAND
Figure 7-7. Handshake Protocol at Command Level
Unlike a normal bit transfer, where the host initiates the transmission by issuing a negative edge in the
BKGD pin, the serial interface ACK handshake pulse is initiated by the target MCU. The hardware
handshake protocol in Figure 7-6 specifies the timing when the BKGD pin is being driven, so the host
should follow these timing constraints in order to avoid the risks of an electrical conflict at the BKGD pin.
The ACK handshake protocol does not support nested ACK pulses. If a BDC command is not
acknowledged by an ACK pulse, the host first needs to abort the pending command before issuing a new
BDC command. When the CPU enters WAIT or STOP mode at about the same time the host issues a
command (such as WRITE_BYTE) that requires CPU execution, the target discards the incoming
command. Therefore, the command is not acknowledged by the target, which means that the ACK pulse
will not be issued in this case. After a certain time the host could decide to abort the ACK protocol in order
allow a new command. Therefore, the protocol provides a mechanism in which a command, and therefore
a pending ACK, could be aborted. Note that, unlike a regular BDC command, the ACK pulse does not
provide a timeout. In the case of a WAIT or STOP instruction where the ACK is prevented from being
issued, the ACK would remain pending indefinitely if not aborted. See the handshake abort procedure
described in section 7.3.6 Hardware Handshake Abort Procedure below.
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7.3.6 Hardware Handshake Abort Procedure
The abort procedure is based on the SYNC command. In order to abort a command that has not
responded with an ACK pulse, the host controller should generate a sync request (by driving BKGD low
for at least 128 serial clock cycles and then driving it high for one serial clock cycle as a speedup pulse).
By detecting this long low pulse on the BKGD pin, the target executes the sync protocol (see 7.3.4.1
SYNC — Request Timed Reference Pulse), and assumes that the pending command and therefore the
related ACK pulse, are being aborted. Therefore, after the sync protocol completes, the host is free to
issue new BDC commands.
Although it is not recommended, the host could abort a pending BDC command by issuing a low pulse on
the BKGD pin that is shorter than 128 BDC clock cycles, which will not be interpreted as the SYNC
command. The ACK is actually aborted when a negative edge is perceived by the target on the BKGD
pin. The short abort pulse should be at least four BDC clock cycles long to allow the negative edge to be
detected by the target. In this case the target will not execute the sync protocol but the pending command
will be aborted along with the ACK pulse. The potential problem with this abort procedure is when there
is a conflict between the ACK pulse and the short abort pulse. In this case the target would not recognize
the abort pulse. The worst case is when the pending command is a read command, as for instance the
READ_BYTE. If the abort pulse is not perceived by the target, the host will attempt to send a new
command after the abort pulse was issued, while the target expects the host to retrieve the accessed
memory byte. Host and target will run out of synchronization in this case. However, if the command to be
aborted is not a read command, the short abort pulse could be used. After a command is aborted, the
target assumes that the next negative edge, after the abort pulse, is the first bit of a new BDC command.
NOTE
The details about the short abort pulse are being provided only as a
reference for the reader to better understand the BDC internal behavior. It
is not recommended that this procedure be used in a real application.
Note that, since the host knows the target BDC clock frequency, the SYNC command does not need to
consider the lowest possible target frequency. In this case, the host could issue a SYNC very close to the
128 serial clock cycles length, just providing a small overhead on the pulse length in order to assure the
sync pulse will not be misinterpreted by the target. See 7.3.4.1 SYNC — Request Timed Reference Pulse.
It is important to notice that any issued BDC command that requires CPU execution will be executed at
the next instruction boundary, provided the CPU does not enter WAIT or STOP modes. If the host aborts
a command by sending the sync pulse, it should then read the BDCSCR after the sync response is issued
by the target, checking for DVF = 0, before attempting to send any new command that requires CPU
execution. This prevents the new command from being discarded at the BDC-CPU interface, due to the
pending command being executed by the CPU. Any new command should be issued only after DVF = 0.
There are two reasons that could cause a command to take too long to be executed, measured in terms
of the serial communication rate. Either the BDC clock frequency is much faster than the CPU bus clock
frequency, or the CPU is accessing a slow memory, which would cause suspend cycles to occur. The
hardware handshake protocol is appropriate for both situations, but the host could also decide to use the
software handshake protocol instead. In this case, if the DVF bit is at logic 1, there is a BDC command
pending at the BDC-CPU interface. The host controller should monitor the DVF bit and wait until it is at
logic 0 in order to be able to issue a new command that requires CPU execution. Note that the WSF bit
in the BDCSCR register should be at logic 0 in this case. However, if the WSF bit was at logic 1, the host
should assume the last command failed due to a WAIT or STOP instruction being executed by the CPU.
In this case, the host controller should enable background mode, using a WRITE_CONTROL command,
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and then issue a BACKGROUND command in order to put the CPU into active background mode. After
that, new commands could be issued, including those that require CPU execution.
Figure 7-8 shows a SYNC command aborting a READ_BYTE. Note that after the command is aborted, a
new command could be issued by the host computer.
NOTE
Figure 7-8 signal timing is not drawn to scale.
READ_BYTE CMD
SYNC RESPONSE
FROM THE TARGET
(NOT TO SCALE)
IS ABORTED BY THE SYNC REQUEST
(NOT TO SCALE)
BKGD PIN
READ_BYTE
MEMORY ADDRESS
HOST
READ_STATUS
TARGET
HOST
TARGET
NEW BDC COMMAND
HOST
TARGET
NEW BDC COMMAND
BDC DECODES
AND STARTS TO EXECUTE
THE READ_BYTE CMD
Figure 7-8. ACK Abort Procedure at the Command Level
Figure 7-9 shows a conflict between the ACK pulse and the sync request pulse. This conflict could occur
if a pod device is connected to the target BKGD pin and the target is already executing a BDC command.
Consider that the target CPU is executing a pending BDC command at the exact moment the pod is being
connected to the BKGD pin. In this case an ACK pulse is issued at the same time as the SYNC command.
In this case there is an electrical conflict between the ACK speedup pulse and the sync pulse. Since this
is not a probable situation, the protocol does not prevent this conflict from happening.
AT LEAST 128 CYCLES
BDC CLOCK
(TARGET MCU)
TARGET MCU
DRIVES TO
BKGD PIN
ACK PULSE
HIGH-IMPEDANCE
ELECTRICAL CONFLICT
HOST
DRIVES SYNC
TO BKGD PIN
HOST AND TARGET
DRIVE TO BKGD PIN
SPEEDUP PULSE
HOST SYNC REQUEST PULSE
BKGD PIN
16 CYCLES
Figure 7-9. ACK Pulse and SYNC Request Conflict
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The hardware handshake protocol is enabled by the ACK_ENABLE command and disabled by the
ACK_DISABLE command. It also allows for pod devices to choose between the hardware handshake
protocol or the software protocol that monitors the BDC status register. The ACK_ENABLE and
ACK_DISABLE commands are:
• ACK_ENABLE — Enables the hardware handshake protocol. The target will issue the ACK pulse
when a CPU command is executed by the CPU. The ACK_ENABLE command itself also has the
ACK pulse as a response.
• ACK_DISABLE — Disables the ACK pulse protocol. In this case the host should verify the state of
the DVF bit in the BDC Status and Control register in order to evaluate if there are pending
commands and to check if the CPU changed to or from active background mode.
The default state of the protocol, after reset, is hardware handshake protocol disabled.
The commands that do not require CPU execution, or that have the status register included in the
retrieved bit stream, do not perform the hardware handshake protocol. Therefore, the target will not
respond with an ACK pulse for those commands even if the hardware protocol is enabled. The commands
are: READ_STATUS, WRITE_CONTROL, WRITE_BYTE_WS, READ_BYTE_WS, READ_NEXT_WS,
WRITE_NEXT_WS, WRITE_BKPT, READ_BKPT, READ_LAST and ACK_DISABLE. See 7.3.4 BDC
Commands for more information on the BDC commands.
NOTE
The TAGGO command does not have the ACK pulse as a response.
Except for no ACK pulse, this command is equivalent to the GO command.
It was implemented for compatibility with previous BDC versions. The
HCS08 core does not provide support for external tag using the BKGD pin.
Only commands that require CPU execution perform the hardware handshake protocol. These
commands are: WRITE_BYTE, READ_BYTE, WRITE_NEXT, READ_NEXT, WRITE_A, READ_A,
WRITE_CCR, READ_CCR, WRITE_SP, READ_SP, WRITE_HX, READ_HX, WRITE_PC, READ_PC.
An exception is the ACK_ENABLE command, which does not require CPU execution but responds with
the ACK pulse. This feature could be used by the host to evaluate if the target supports the hardware
handshake protocol. If an ACK pulse is issued in response to this command, the host knows that the
target supports the hardware handshake protocol. If the target does not support the hardware handshake
protocol the ACK pulse is not issued. In this case the ACK_ENABLE command is ignored by the target,
since it is not recognized as a valid command.
The BACKGROUND command will issue an ACK pulse when the CPU changes from running user code
to active background mode. The ACK pulse related to this command could be aborted using the SYNC
command.
The GO command will issue an ACK pulse when the CPU exits from active background mode. The ACK
pulse related to this command could be aborted using the SYNC command.
The TRACE1 command has the related ACK pulse issued when the CPU enters active background mode
after one instruction of the application program is executed. The ACK pulse related to this command could
be aborted using the SYNC command.
The GO_UNTIL command is equivalent to a GO command with exception that the ACK pulse, in this case,
is issued when the CPU enters into active background mode. This command is an alternative to the GO
command and should be used if the host wants to trace if a breakpoint match had occurred which caused
the CPU to enter active background mode. Note that the ACK is issued whenever the CPU enters BDM,
which could be caused by a BDC breakpoint match, or an external force/tag, or by a BGND instruction
being executed. The ACK pulse related to this command could be aborted using the SYNC command.
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The TAGGO command is equivalent to the GO command, but will not have an ACK pulse as a response.
This command is being kept for backwards compatibility reasons. The GO command should be used
instead.
7.3.7 BDC Hardware Breakpoint
The BDC includes one relatively simple hardware breakpoint which 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 be placed only 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 8-bit BDCSCR and the 16-bit BDCBKPT address match register are built directly into the BDC and
are not accessible in the normal MCU memory map. This means that the user application program cannot
access these registers. Dedicated BDC serial commands are the only way to access these registers.
READ_STATUS and WRITE_CONTROL are used to read or write BDCSCR, respectively. READ_BKPT
and WRITE_BKPT are used to read or write the 16-bit BDCBKPT address match register. A host debug
pod can read or write these registers at any time even while a user application program is running.
However, it is more common to adjust breakpoint settings while the MCU is in active background mode.
The BDC provides access to control and status signals, which allows more complex breakpoints to be
built outside the BDC logic but still on the MCU chip. Some HCS08 derivatives may have additional, more
complex, hardware breakpoints. These additional breakpoints need any associated registers and control
bits to be accessible through reads and writes to addresses in the normal MCU memory map.
7.3.8 Differences from M68HC12 BDM
Although the bit-level communication protocol is the same as the background debug mode (BDM)
interface in the M68HC12 Family, the HCS08 has implemented the background debug controller (BDC)
differently than the M68HC12 to reduce the silicon area and to provide new capabilities.
In the M68HC12, the BDM is implemented separately from the CPU and uses a small firmware ROM to
control active background mode operations. The HCS08, on the other hand, incorporates background
functions directly into the logic of the core CPU, thus eliminating the firmware ROM.
In the HCS08, BDC registers are never in the memory map of the target MCU, so there is no need for the
READ_BD_BYTE, READ_BD_WORD, WRITE_BD_BYTE, and WRITE_BD_WORD commands of the
M68HC12.
Since the HCS08 CPU has a different CPU register model, the BDC commands that read and write CPU
registers are different than those for the M68HC12. In the M68HC12 BDM, the condition codes were
stored in a register in the BDM memory map so reading and writing the CCR were done with
READ_BD_BYTE and WRITE_BD_BYTE commands. READ_BD_BYTE and WRITE_BD_BYTE were
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also used to read and write the BDM status register. In the HCS08, however, there are separate
commands for reading and writing the status/control register which is not in the memory map of the MCU.
7.3.8.1 8-Bit Architecture
Unlike the 16-bit M68HC12, the HCS08 is an 8-bit architecture. Because of this, the HCS08 BDC does
not have word-sized read and write commands. Also, the READ_NEXT and WRITE_NEXT commands
operate on byte-sized data rather than word-sized data.
7.3.8.2 Command Formats
All data fields in the M68HC12 BDM are 16 bits even if the command only requires eight bits of data. In
contrast, in the HCS08, data fields match the size of the data needed so a command like READ_BYTE
will have an 8-bit data field while RD_BYTE_WS has a 16-bit data field to hold the BDC system STATUS
byte followed by the data byte.
In the M68HC12 Family, the BDM can wait up to 128 cycles for a free bus cycle to appear to allow the
BDM access without disturbing the running user application program. If no free cycle is found, the BDM
temporarily freezes the CPU to allow the BDM to complete the requested operation. In the HCS08, this
has been simplified such that the BDC always steals a cycle as soon as it can. This has little impact on
real-time operation of the user’s code because a memory access command takes 8 bits for the command,
16 bits for the address, at least eight bits for the data, and a 16-cycle delay within the command. Each bit
time is at least 16 BDC clock cycles so (32 x 16) +16 = 528 cycles, thus the worst case impact is no more
than 1/528 cycles, even if there are continuous back-to-back memory access commands through the
BDM (which would be very unlikely).
Since the HCS08 BDC doesn’t wait for free cycles, the delays between address and data in read
commands and the delay after the data portion of a write command can be much shorter than the 150
cycles recommended for the M68HC12 BDM. In the HCS08, the delay within a memory access command
is 16 target bus cycles. For accesses to registers within the BDC (STATUS, and BDCBKPT address
match registers), no delay is needed.
7.3.8.3 Read and Write with Status
Because the memory access commands in the HCS08 BDC are actually performed by the CPU circuitry,
it is possible for a memory access to fail to complete within the BDC command. The two cases where this
can occur are: When the memory access command coincides with the CPU entering stop or wait, or if the
CPU was performing a slow memory access when the BDC command arrived. (In HCS08 versions that
do not include slow memory devices, this case cannot occur.)
Since there is normally no way to predict when the target CPU might perform a slow access or a STOP
or WAIT instruction, the DVF status bit was added to indicate an access error due to a slow access, and
the WSF status bit was added to indicate an access failed because the CPU was just entering wait or stop
mode. Alternate variations of the READ_BYTE, WRITE_BYTE, READ_NEXT, and WRITE_NEXT
commands have been added which automatically return the contents of the BDC status register along
with the data portion of the command. In the case of the READ_BYTE and READ_NEXT commands, the
READ_BYTE_WS and READ_NEXT_WS commands can be thought of as returning 16 bits of data. In
the case of the WRITE_BYTE and WRITE_NEXT commands, the WRITE_BYTE_WS and
WRITE_NEXT_WS commands include the byte of status information in the target-to-host direction after
the write data byte (which is in the host-to-target direction).
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7.3.8.4 BDM Versus Stop and Wait Modes
In the M68HC12 Family, the BDM system is implemented independently from the CPU so memory access
commands can still be performed while the target MCU is in wait mode. Stop mode in the M68HC12
causes the oscillator, from which all system clocks are derived, to be stopped. The BDM ceases to
function because it has no clocks.
However, the clock architecture of the HCS08 permits the BDC to prevent the oscillator from stopping
during stop mode if the ENBDM control bit is set. In such a system, the debug host can use
READ_STATUS commands to tell if the target is in wait or stop mode. If the target is in wait or stop (WS
bit equals 1), the BACKGROUND command may be used to awaken the target and place it in active
background mode.
From active background mode, the debug host can read or write memory or registers. The debug host
can then choose to adjust the stack and PC such that a GO command will return the target MCU to wait
or stop mode.
7.3.8.5 SYNC Command
The HCS08 has added a SYNC command to allow the host interface pod to determine the correct speed
for optimum communications with the target MCU. This is especially useful when the BDC clock in the
target MCU is operating from an internal self-clocked local oscillator rather than the CPU bus clock.
To use the SYNC command, the host drives the BKGD pin low for at least 128 target BDC clock cycles
then releases the low drive and drives a brief speedup pulse to snap the BKGD pin back to a good logic
high level before reverting to high impedance. After a delay to allow the BKGD pin to reach a good high
level and to avoid possible interference with the high-driven speedup pulse from the host, the target will
drive the BKGD pin low for 128 target BDC clock cycles followed by a 1-cycle driven-high speedup pulse
and then reverts to high impedance. The host can measure the duration of this sync pulse to accurately
determine the speed of the target’s BDC clock.
7.3.8.6 Hardware Breakpoint
The BDC in the HCS08 includes one 16-bit hardware breakpoint which triggers on a match against the
16-bit address bus. Specific HCS08 derivatives may include additional on-chip hardware breakpoints
outside the BDC. The READ_BKPT and WRITE_BKPT commands allow reading or writing the BDCBKPT
(address match) register which is built into the BDC logic.
There are also two control bits for the breakpoint in the BDCSCR:
• The BKPTEN bit enables the breakpoint to generate a trigger event in response to a match
between the BDCBKPT register and the CPU address bus.
• The force/tag select (FTS) bit determines what a breakpoint trigger event does.
If FTS = 1 (force), the trigger event causes the target MCU to enter active background mode at the next
instruction boundary. If FTS = 0 (tag), the trigger event causes the fetched data value to be tagged as it
enters the instruction queue. If and when this tagged opcode reaches the top of the queue, the target
MCU enters active background mode rather than executing the tagged instruction. The address in the
BDCBKPT register must point to an instruction opcode for the tag type breakpoints, but it can be set to
any address for a force type breakpoint.
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7.4 Part Identification and BDC Force Reset
HCS08 devices include two additional development support features that are not part of the background
debug controller (BDC) or debug (DBG) modules. These registers are described in this section.
A 16-bit register pair in the system integration module (SDIDH:SDIDL) provides a way for a development
host to determine the derivative type and mask set revision of a target MCU. This allows the development
system to associate a register definition file with the target MCU so debug software in the host can know
where various memory blocks start and end in the target and the locations for registers and control bits.
An 8-bit control register includes a BDM force reset (BDFR) control bit that allows a host development
system to reset the target MCU via a serial command through the background debug communication
interface. The BDFR bit is not accessible by user application programs in the target MCU so there is no
possibility that a runaway program could accidentally trigger this reset function.
7.4.1 System Device Identification Registers (SDIDH:SDIDL)
This 16-bit read-only register pair is hard-coded with the mask set revision number and derivative
identification code.
Read:
Bit 7
6
5
4
3
2
1
Bit 0
REV3
REV2
REV1
REV0
ID11
ID10
ID9
ID8
ID1
ID0
Reset: The value of these bits depends on the device type and mask set revision.
Read:
ID7
ID6
ID5
ID4
ID3
ID2
Reset: The value of these bits depends on the device type and mask set revision.
Figure 7-10. System Device Identification Register
REV[3:0] — Mask set Revision Number
This 4-bit field is hard coded to reflect the mask set revision number (0–F) for the MCU die. The initial
release of a part is revision number 0:0:0:0.
ID[11:0] — Part Identification Code
This 12-bit field is hard coded with an identification number that identifies the HSC08 derivative type.
For example the code for the MC9S08GB60 is $002. Refer to the technical data sheet for other
derivatives to find their codes.
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7.4.2 System Background Debug Force Reset Register
This register is located in the system integration module, not in the BDC. The system background debug
force reset register (SBDFR) is an 8-bit register containing a single control bit which is accessible only
from the background debug controller. A serial background command such as WRITE_BYTE must be
used to write to SBDFR and attempts to write this register from a user program are ignored. Unlike the
other registers in the BDC, SBDFR is located in the normal address space of the MCU (normally located
at $1801).
Read:
Bit 7
6
5
4
3
2
1
Bit 0
0
0
0
0
0
0
0
0
BDFR
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 7-11. System Background Debug Force Reset Register (SBDFR)
BDFR — Background Debug Force Reset
This write-only control bit provides a means for the background debug host to reset the target MCU
without having access to a reset pin.
1 = Force a target system reset.
0 = Writing 0 has no meaning or effect.
7.5 On-Chip Debug System (DBG)
Since 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 which can store address or data bus information, and a flexible trigger system to decide when to
capture bus information and what information to capture. This is a little like having a logic analyzer or bus
state analyzer built inside the MCU. The system does not use any MCU pins. Rather, it relies on the
background debug system (or the CPU) to access debug control registers and to read results out of the
8-stage FIFO.
Unlike the background debug controller, the debug module does include 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 two exceptions are a ROM-based debug
monitor program and ROM patching, a serial monitor program is discussed in application note AN2140/D.
ROM patching is discussed in greater detail in 7.5.9 Hardware Breakpoints and ROM Patching.
7.5.1 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. R/W can be used to detect matches on only read cycles or only write cycles. Separate control bits
allow R/W to be ignored 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 just being read from memory into the instruction queue. This feature allows you to ignore fetches of
instructions where a change of flow from a jump, branch, or interrupt causes the CPU to re-fill the
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instruction queue rather than execute the unused instructions in the queue. The comparators also are
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
16-bit CPU address or the 8-bit CPU data bus, depending on the trigger mode selected. Since the CPU
data bus is separated into a read data bus and a write data bus, the RWAEN and RWA control bits are
used to decide which of these buses to use in 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)
7.5.2 Bus Capture Information and FIFO Operation
Although processing technology has made on-chip logic less expensive, it still isn’t free. Because of this,
the number of words of bus capture information that can be stored at a time is limited (eight words in the
first HCS08 devices).
To compensate for this limitation, the debugger uses two strategies:
• For tracking the sequence of program instructions, the FIFO only captures addresses related to
changes of flow. This allows an external host development tool to reconstruct the flow through
dozens or even hundreds of instructions from the eight change-of-flow events before or after a
selected trigger point.
• The second strategy is to selectively capture event information. This technique is used to capture
only the data associated with read and/or write accesses to a specific address or register.
The usual way to use the FIFO is to set up 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, 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.
In most trigger modes, the information stored in the FIFO consists of change-of-flow addresses (16-bit
values). In these cases, read DBGFH then DBGFL to get one word of information out of the FIFO.
Reading DBGFL (the low-order half 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, 8-bit data information is
stored into the FIFO. In these cases, the high-order half of the FIFO (DBGFH) is not used (always stores
and reads 0s) 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. One consequence of this delay is that if the trigger event itself
is a change-of-flow address or if 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.
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In event-only trigger modes where the FIFO is storing data, the BEGIN control bit is ignored and all
event-only trigger modes are begin-type traces. The event which triggers the start of FIFO data storage
is captured as the first data word in the FIFO.
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 currently executing instruction 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.
7.5.3 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 instruction). If the external debugger finds such
an address in the FIFO, it may assume that the branch was taken. Because BRA and BRN instructions
are predictable, 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 external debugger cannot predict the destination address from only
information in the source and object code. For this reason, the debug system stores the run-time
destination address for any indirect JMP or JSR. However, for other JMP and JSR instructions, the
external debugger can determine the destination from known source and object code, so no information
is stored in the debug FIFO.
For interrupts, return from interrupt (RTI), or return from subroutine (RTS), the destination address is
stored in the FIFO as change-of-flow information. In the case of interrupts, the external debugger could
tell where the interrupt vector would take program execution, but the debug module needs to store this
destination address (address of the interrupt service routine) so the external debugger knows that an
interrupt has taken place and execution continued at this address. The destination of an RTI tells the
external debugger where the interrupt was recognized in the normal program sequence. RTI and RTS get
their destination address from the current values on the stack. The external debugger cannot reliably
predict this return address from only the information in the source and object code. Program errors that
cause stack problems can be detected by analysis of the change-of-flow information.
Since the FIFO in this debug module is only eight words deep, some care is required when setting up
debug runs. For example, if the FIFO is set up to start capturing change-of-flow addresses just before a
small loop or a DBNZ instruction that branches to itself, the FIFO will fill very quickly and the information
captured will be of little help in debugging a program. Instead, a debug run could be set for an end-trace
to show the execution leading to the first iteration of the loop. Another end-trace could be set up to stop
at an instruction just after the loop to monitor the behavior of the program for the last iteration of the loop.
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7.5.4 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. Usually, you are only interested in instructions if they are actually executed so the tag
mechanism allows you to selectively ignore fetches that do not lead to execution.
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 (or SWI if background mode is disabled
(ENBDM = 0)).
The second context is when the TRGSEL control bit in the DBGT register is set to select tag-type
operation. In this case, the output from comparator A or B is qualified by a block of logic in the debug
module that tracks opcodes and the debugger only produces a trigger 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 rebuilt instruction queue at a time. TRGSEL has no effect
on breakpoint requests to the CPU.
7.5.5 CPU Breakpoint Requests
In end-trace debug runs (BEGIN = 0), for all trigger modes except event-only modes, CPU breakpoint
requests are generated when the trigger event occurs. In begin-trace debug runs (BEGIN = 1), CPU
breakpoint requests are generated when the FIFO has been filled. Event-only trigger modes are always
begin trace debug runs, so CPU breakpoint requests are generated when the FIFO has been filled.
BRKEN = TAG = 1 while TRGSEL = BEGIN = 0 is a special case that should be avoided because the
results could be confusing. When the address match occurs, a tag-type breakpoint request is issued to
the CPU. If an exception occurs before this tag reaches the end of the pipe, the intended opcode will be
flushed from the pipe, but the tag request from the DBG module remains active waiting for the CPU to
acknowledge that it has entered active background mode. The first opcode for the interrupt service routine
will end up getting tagged and this is where the CPU will stop rather than at the intended opcode at the
match address. To avoid this case, TRGSEL should have been set to 1.
7.5.6 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. The TRGSEL control bit in the DBGT register modifies the chosen
mode by setting whether comparator signals are qualified by opcode tracking logic. 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 until the qualified trigger is detected (end trigger).
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In all trigger modes except the two event-only modes, the FIFO stores change-of-flow addresses. In
event-only trigger modes, the FIFO stores 8-bit data values.
In all trigger modes, a match condition for comparator A and/or B is optionally qualified by read/write
(R/W) and pipe rebuild logic. R/W comparison is enabled by the associated RWxEN control bit and can
be considered an additional input to the associated comparator. In full trigger modes, RWAEN and RWA
can be used to enable comparison of R/W and to control whether data comparisons use the CPU read or
write data bus and RWBEN and RWB are ignored. When TRGSEL = 1, the R/W qualified match condition
is entered into instruction pipe rebuild logic so the trigger is not produced until/unless the tagged opcode
reaches the end of the pipe rebuild logic. In event-only trigger modes, TRGSEL is ignored and match
signals are never qualified through the pipe rebuild logic.
Begin-trace debug runs start filling the FIFO when the trigger conditions are met and end when the FIFO
becomes full (CNT[3:0] = 1:0:0:0). End-trace debug runs start filling the FIFO in circular fashion when the
ARM bit is set to 1, and end when the trigger conditions are met. End-trace debug runs can end before
the FIFO is full. If more than eight entries are stored into the FIFO during an end-trace debug run, new
entries overwrite the oldest entry in the FIFO so that when the debug run ends, the information in the FIFO
will be the eight most recent change-of-flow addresses.
A debug run is started by setting up the DBGT register and then writing a 1 to the ARM bit in the DBGC
register which sets the ARMF flag and clears the A and B 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 the DBGEN bit in DBGC.
7.5.6.1 A-Only Trigger
In the A-only trigger mode, a qualified match on comparator A sets the AF status flag and generates a
trigger event. DBGCAH:DBGCAL is compared against the 16-bit CPU address and triggers may be
qualified with R/W (by setting RWAEN = 1) and/or by pipe rebuild logic (by setting TRGSEL = 1).
7.5.6.2 A OR B Trigger
In the A OR B trigger mode, a qualified match on comparator A or on comparator B sets the corresponding
AF or BF status flag and generates a trigger event. DBGCAH:DBGCAL and DBGCBH:DBGCBL are
compared against the 16-bit CPU address and triggers may be qualified with R/W (by setting RWAEN
and/or RWBEN to 1) and/or by pipe rebuild logic (by setting TRGSEL=1).
7.5.6.3 A Then B Trigger
In the A Then B trigger mode, a qualified match on comparator A followed by a qualified match on
comparator B generates a trigger event. The AF status flag gets set when a qualified match occurs on
comparator A. After AF is set, a qualified match on comparator B sets the BF status flag and generates
the trigger. DBGCAH:DBGCAL and DBGCBH:DBGCBL are compared against the 16-bit CPU address
and triggers may be qualified with R/W (by setting RWAEN and/or RWBEN to 1) and/or by pipe rebuild
logic (by setting TRGSEL = 1).
7.5.6.4 Event-Only B Trigger (Store Data)
In event-only trigger modes, data values are stored in the FIFO rather than change-of-flow addresses. In
the event-only B trigger mode, a qualified match on comparator B sets the BF status flag and generates
a trigger event. DBGCBH:DBGCBL is compared to the 16-bit CPU address. Triggers may be qualified
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with R/W by setting RWBEN to 1. Do not use TRGSEL = 1 in an event-only trigger mode.
DBGCAH:DBGCAL, RWAEN, and RWA are not used in this mode.
7.5.6.5 A Then Event-Only B Trigger (Store Data)
In event-only trigger modes, data values are stored in the FIFO rather than change-of-flow addresses. In
the A then event-only B trigger mode, a qualified match on comparator A sets the AF status flag. After AF
is set, a qualified match on comparator B sets the BF status flag and generates a trigger event.
DBGCAH:DBGCAL and DBGCBH:DBGCBL are compared to the 16-bit CPU address. Triggers may be
qualified with R/W by setting RWAEN and/or RWBEN to 1. Do not use TRGSEL = 1 in an event-only
trigger mode.
7.5.6.6 A AND B Data Trigger (Full Mode)
This is called a full mode because address, data, and optionally R/W must all match within the same bus
cycle to cause a trigger. In the A AND B data trigger mode, a qualified match on comparator A and on
comparator B within the same bus cycle generates a trigger event. The AF and BF status flags get set
when a qualified match occurs on comparator A and on comparator B in the same bus cycle.
DBGCAH:DBGCAL is compared to the 16-bit CPU address and DBGCBL is compared against the 8-bit
CPU data bus. If RWAEN = 1 and RWA = 0, DBGCBL is compared to the CPU write data bus; otherwise,
DBGCBL is compared to the CPU read data bus. Triggers may be qualified with R/W (by setting RWAEN
to 1) and/or by pipe rebuild logic (by setting TRGSEL = 1). DBGCBH, RWBEN, and RWB are not used in
this mode.
7.5.6.7 A AND NOT B Data Trigger (Full Mode)
This is called a full mode because address, data, and optionally R/W are all tested within the same bus
cycle to cause a trigger. In the A AND NOT B data trigger mode, a qualified match on comparator A, within
a bus cycle where data does not match comparator B, generates a trigger event. The AF and BF status
flags get set when a qualified match occurs on comparator A and not on comparator B in the same bus
cycle. DBGCAH:DBGCAL is compared to the 16-bit CPU address and DBGCBL is compared against the
8-bit CPU data bus. If RWAEN=1 and RWA=0, DBGCBL is compared to the CPU write data bus,
otherwise DBGCBL is compared to the CPU read data bus. Triggers may be qualified with R/W (by setting
RWAEN to 1) and/or by pipe rebuild logic (by setting TRGSEL=1). DBGCBH, RWBEN, and RWB are not
used in this mode.
7.5.6.8 Inside Range Trigger: A ≤ Address ≤ B
In this trigger mode, the comparators are used in a magnitude comparator mode. If the address is greater
than or equal to the address in comparator A in the same cycle when the address is less than or equal to
the address in comparator B, the AF and BF status flags are set and a trigger event is generated.
DBGCAH:DBGCAL and DBGCBH:DBGCBL are compared against the 16-bit CPU address and triggers
may be qualified with R/W (by setting RWAEN and/or RWBEN to 1) and/or by pipe rebuild logic (by setting
TRGSEL = 1). Obviously, the address in DBGCAH:DBGCAL should be less than the address in
DBGCBH:DBGCBL and if RWAEN = RWBEN = 1, RWA should be the same as RWB.
7.5.6.9 Outside Range Trigger: Address < A or Address > B
In this trigger mode, the comparators are used in a magnitude comparator mode. If the address is less
than the address in comparator A or greater than the address in comparator B, a trigger event is
generated. The AF status flag is set if the address is less than the address in comparator A and the BF
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status flag is set if the address is greater than the address in comparator B. DBGCAH:DBGCAL and
DBGCBH:DBGCBL are compared against the 16-bit CPU address and triggers may be qualified with R/W
(by setting RWAEN and/or RWBEN to 1) and/or by pipe rebuild logic (by setting TRGSEL = 1). Obviously,
the address in DBGCAH:DBGCAL should be less than the address in DBGCBH:DBGCBL.
7.5.7 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-based debug monitor or a ROM
patching mechanism that uses the breakpoint logic.
The modular methodology that is used for HCS08 MCUs implements the fine address decode within each
module, but decode logic at the chip level is used to determine the base location for each module. For
this reason, always check the documentation for each derivative to determine absolute address locations
for registers. Generally, the user will access registers by name and an equate or header file provided by
Freescale will translate the register name into the appropriate absolute address for the specific HCS08
derivative. Since registers may not be located at the same address for every derivative MCU, this book
only refers to registers and control bits by their names.
7.5.7.1 Debug Comparator A High Register (DBGCAH)
Compare value bits for the high-order eight bits of comparator A. This register is forced to $00 at reset
and can be read any time and written only when the ARM bit in the DBGC register is not set.
7.5.7.2 Debug Comparator A Low Register (DBGCAL)
Compare value bits for the low-order eight bits of comparator A. This register is forced to $00 at reset and
can be read any time and written only when the ARM bit in the DBGC register is not set.
7.5.7.3 Debug Comparator B High Register (DBGCBH)
Compare value bits for the high-order eight bits of comparator B. This register is forced to $00 at reset
and can be read any time and written only when the ARM bit in the DBGC register is not set.
7.5.7.4 Debug Comparator B Low Register (DBGCBL)
Compare value bits for the low-order eight bits of comparator B. This register is forced to $00 at reset and
can be read any time and written only when the ARM bit in the DBGC register is not set.
7.5.7.5 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 modes of operation, the FIFO only stores information into the
low-order half 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.
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7.5.7.6 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 an event-only mode, 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
result in improper sequencing of information in the FIFO.
Reading DBGFL while the FIFO is not armed causes the current opcode address 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 executed.
The information stored into the FIFO on reads of DBGFL (while the FIFO is not armed) is the address of
the most recently executed opcode. Storing instantaneous address bus values would be much less useful
since you wouldn’t know whether these were data, operand, or instruction accesses.
7.5.7.7 Debug Control Register
This register can be read at any time. The DBGEN and ARM bits can be written at any time. The remaining
bits in the register can be written only while ARM = 0.
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
DBGEN
ARM
TAG
BRKEN
RWA
RAWEN
RWB
RWBEN
0
0
0
0
0
0
0
0
Figure 7-12. Debug Control Register (DBGC)
DBGEN — Debug Module Enable Bit
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 Bit
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 stopped manually by writing 0 to ARM or to DBGEN.
1 = Debugger armed
0 = Debugger not armed
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TAG — Tag/Force Select Bit
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 Bit
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. CPU break
requests are issued to the CPU when the comparator(s) and R/W meet the trigger requirements. CPU
tag requests must coincide with an opcode fetch so TRGSEL never affects when CPU break requests
are issued.
1 = Triggers (before TRGSEL qualification) cause a break request to the CPU
0 = Break requests not enabled
RWA — R/W Comparison Value for Comparator A Bit
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 match only on a read cycle.
0 = Comparator A can match only on a write cycle.
RWAEN — Enable R/W for Comparator A Bit
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 Bit
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 Bit
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.
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7.5.7.8 Debug Trigger Register
This register can be read at any time, but it can be written only while ARM = 0. Bits 4 and 5 are hardwired
to 0s.
Read:
Write:
Reset:
Bit 7
6
TRGSEL
BEGIN
0
0
5
4
0
0
0
0
3
2
1
Bit 0
0
0
TRG
0
0
= Unimplemented or Reserved
Figure 7-13. Debug Trigger Register (DBGT)
TRGSEL — Trigger Type Bit
Controls whether the match outputs from comparators A and B are qualified with the opcode tracking
logic in the debug module. A separate control bit (TAG) in DBGC controls whether CPU break requests
are qualified with separate opcode tracking logic in the CPU.
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 if the opcode at the match address is actually executed. This
trigger event stops (BEGIN = 0) or starts (BEGIN = 1) the capture of information into the FIFO.
1 = Trigger if opcode at compare address is executed (tag)
0 = Trigger on access to compare address (force)
BEGIN — Begin/End Trigger Select Bit
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-type traces.
1 = Trigger initiates data storage (begin trace)
0 = Data stored in FIFO until trigger (end trace)
TRG3:TRG2:TRG1:TRG0 — Select Trigger Mode Bits
Selects one of nine triggering modes
Table 7-2. 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
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7.5.7.9 Debug Status Register
This is a read-only status register.
Read:
Bit 7
6
5
4
AF
BF
ARMF
0
0
0
0
0
3
2
1
Bit 0
0
0
CNT
Write:
Reset:
0
0
= Unimplemented or Reserved
Figure 7-14. 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.
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 7-3. 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
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7.5.8 Application Information and Examples
Assuming no debug run is already in progress (ARMF = 0), the usual sequence used to setup a new
debug run is:
1. Write address or address and data match values to DBGCAH:DBGCAL and/or
DBGCBH:DBGCBL.
2. Write to DBGT to:
– Select a begin/end type trace run (BEGIN = 1/0)
– Select address/opcode qualification (TRGSEL = 0/1)
– Select 1 of 9 basic trigger modes (TRG[3:0])
3. Write to DBGC to:
– Enable the DBG module (DBGEN = 1)
– Decide whether to request a CPU breakpoint (BRKEN = 1)
– If so, select a force/tag CPU breakpoint type (TAG = 0/1)
– Arm the debug run (ARM = 1)
– Setup and enable optional R/W qualifiers
4. Start the user application program with a GO command through the background debug interface.
Although it is technically possible to setup a debug run while the application program is running, it
is much more common to stop the user application program so it is in active background mode
while the debug run is set up.
Depending on the type of debug run that was set up, the target MCU will finish the debug run and enter
active background mode, or the host debugger can monitor the ARMF flag through active background
mode commands to determine when the run is finished. After the debug run is finished, the host would:
1. Optionally read DBGS to see how many words of information were captured into the debug FIFO.
If the host was reading DBGS to determine when the debug run was finished, it may not be
necessary to re-read DBGS to get the CNT[3:0] information. For many debug runs, it is safe to
assume the FIFO is full, so it is not always necessary to check the CNT[3:0] bits to determine how
much information is in the FIFO.
2. Read the FIFO information by repeatedly reading DBGFH then DBGFL. For some debug runs, the
information in the FIFO is not important so it is not necessary to read it out. For event type debug
runs (TRG[3:0] = 0:0:1:1 or 0:1:0:0, the upper-half each of FIFO word is unused so it is not
necessary to read DBGFH.
The four control bits BEGIN and TRGSEL in DBGT, and BRKEN and TAG in DBGC, determine the basic
type of debug run as shown in Table 7-4. Some of the 16 possible combinations are not used (refer to the
notes at the end of the table).
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Table 7-4. Basic Types of Debug Runs
BEGIN
TRGSEL
BRKEN
TAG
Type of Debug Run
0
0
0
x(1)
0
0
1
0
Fill FIFO until trigger address, then force CPU breakpoint
0
0
1
1
Don’t use(2)
0
1
0
x(1)
0
1
1
0
Don’t use(3)
0
1
1
1
Fill FIFO until trigger opcode about to execute (trigger causes CPU
breakpoint)(4)
1
0
0
x(1)
Start FIFO at trigger address (No CPU breakpoint — keep running)
1
0
1
0
Start FIFO at trigger address, force CPU breakpoint when FIFO full
1
0
1
1
Don’t use(4)
1
1
0
x(1)
Start FIFO at trigger opcode, (No CPU breakpoint — keep running)
1
1
1
0
Start FIFO at trigger opcode, force CPU breakpoint when FIFO full
1
1
1
1
Don’t use(5)
Fill FIFO until trigger address (No CPU breakpoint — keep running)
Fill FIFO until trigger opcode about to execute (No CPU breakpoint —
keep running)
1. When DBGEN = 0, TAG is don’t care (x in the table).
2. In end trace configurations (BEGIN = 0) where a CPU breakpoint is enabled (BRKEN = 1), TRGSEL should agree with
TAG. In this case, where TRGSEL = 0 to select no opcode tracking qualification and TAG = 1 to specify a tag-type CPU
breakpoint, the CPU breakpoint would not take effect until sometime after the FIFO stopped storing values. Depending on
program loops or interrupts, the delay could be very long.
3. In end trace configurations (BEGIN = 0) where a CPU breakpoint is enabled (BRKEN = 1), TRGSEL should agree with
TAG. In this case, where TRGSEL = 1 to select opcode tracking qualification and TAG = 0 to specify a force-type CPU
breakpoint, the CPU breakpoint would erroneously take effect before the FIFO stopped storing values and the debug run
would not complete normally.
4. In begin trace configurations (BEGIN = 1) where a CPU breakpoint is enabled (BRKEN = 1), TAG should not be set to 1.
In begin trace debug runs, the CPU breakpoint corresponds to the FIFO full condition which does not correspond to a taggable instruction fetch.
7.5.8.1 Orientation to the Debugger Examples
The following sections describe how to setup debug runs for several common situations. Each of these
examples starts with a table similar to the one shown here:
DBGCAH:DBGCAL
Opcode address
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Not used
RWBEN(1)
RWB(1)
DBGT
DBGC
x
x
$00
$D0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
To set up and use a debug run like that described in each example, write the values in the table to the
registers named in the heading for each column. The registers should be written in left-to-right order. The
RWAEN, RWA, RWBEN, and RWB values are shown in separate columns of the table for convenience,
but these are actually control bits in the DBGC register. These bit values are already reflected in the value
for DBGC at the right end of the table and these bits get written when DBGC is written.
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Just below this table in each example section, the trigger mode is shown and a description of the contents
of the FIFO after the debug run is shown. The trigger mode can be derived from the low-order four bits of
the DBGT value shown near the right of the table, but it is listed separately for easier reference. After
explaining the details and purpose of each example case, variations are discussed.
7.5.8.2 Example 1: Stop Execution at Address A
DBGCAH:DBGCAL
Trigger address A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Not used
RWBEN(1)
RWB(1)
DBGT
DBGC
x
x
$00
$D0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A-only
FIFO contents: Not used in this example
This is a simple hardware breakpoint where the CPU will stop executing the application program and enter
active background mode as soon as the application program makes any access to the selected address.
It generates a force-type breakpoint to the CPU on the first access (R/W is don’t care) to the address
stored in comparator A (DBGCAH:DBGCAL). The FIFO, comparator B, and DBGS are not used for this
example.
An end trace is used because begin-type traces cause the breakpoint to the CPU to be related to the FIFO
full condition rather than the selected trigger conditions.
Variation: To consider only read accesses or only write accesses, change the DBGC value so
RWAEN = 1 and use RWA to select reads (1) or writes (0).
7.5.8.3 Example 2: Stop Execution at the Instruction at Address A
DBGCAH:DBGCAL
Trigger opcode A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Not used
RWBEN(1)
RWB(1)
DBGT
DBGC
x
x
$80
$F0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A-only
FIFO contents: Not used in this example
This example uses a tag-type breakpoint to the CPU to set a single instruction breakpoint at address A.
The address stored to comparator A (DBGCAH:DBGCAL) must be the address of an instruction opcode.
When the selected instruction is about to execute, the CPU will go to active background mode rather than
execute the tagged instruction. 0 is written to RWAEN because in order for the instruction to be entered
into the CPU’s instruction queue it has to be a read access, so there is no need to check R/W. The FIFO,
comparator B, and DBGS are not used for this example.
An end trace is used because begin-type traces cause the breakpoint to the CPU to be related to the FIFO
full condition rather than the selected trigger conditions. Since this is an end-type trace and we want a
tag-type breakpoint to the CPU, we must also specify a tag-type trigger (TRGSEL = 1). If the specified
address is not the address of an instruction opcode, no breakpoint will occur.
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7.5.8.4 Example 3: Stop Execution at the Instruction at Address A or Address B
DBGCAH:DBGCAL
Trigger opcode A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Trigger opcode B
RWBEN(1)
RWB(1)
DBGT
DBGC
0
x
$81
$F0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A or B
FIFO contents: Not used in this example
This example uses tag-type breakpoints to the CPU to set two instruction breakpoints, one at address A
and the other at address B. The addresses stored to comparator A (DBGCAH:DBGCAL) and comparator
B (DBGCBH:DBGCBL) must be the addresses of instruction opcodes. When either of the selected
instructions is about to execute, the CPU will go to active background mode rather than execute the
tagged instruction. 0 is written to RWAEN and RWBEN because in order for the instruction to be entered
into the CPU’s instruction queue it has to be a read access, so there is no need to check R/W. The FIFO
and DBGS are not used for this example.
An end trace is used because begin-type traces cause the breakpoint to the CPU to be related to the FIFO
full condition rather than the selected trigger conditions. Since this is an end-type trace and we want a
tag-type breakpoint to the CPU, we must also specify a tag-type trigger (TRGSEL = 1). If the specified
addresses are not the addresses of instruction opcodes, no breakpoint will occur.
7.5.8.5 Example 4: Begin Trace at the Instruction at Address A
DBGCAH:DBGCAL
Trigger opcode A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Not used
RWBEN(1)
RWB(1)
DBGT
DBGC
x
x
$C0
$D0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A-only
FIFO contents: Information from the next eight changes of flow starting from the third bus cycle after the
instruction at address A began to execute.
This is an example of a begin-trace debug run that starts filling the FIFO when the instruction at address
A is executed and ends when the FIFO is full (has stored eight change-of-flow addresses). Because of a
delay in the debug logic, the first possible change-of-flow address that will be captured into the FIFO is
the third bus cycle after the trigger event that starts the debug run. If the address when the instruction that
caused the trigger, or either of the next two bus cycles is a change-of-flow address, it will not be captured
as one of the eight change-of-flow addresses in the FIFO for this debug run.
A force-type CPU breakpoint is specified because this breakpoint is associated with the FIFO full
condition and not a taggable opcode. The CPU breakpoint causes the target MCU to go to active
background mode as soon as the FIFO is full. Typically, a host development system would then read the
contents of the FIFO in order to reconstruct what happened during the debug run.
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7.5.8.6 Example 5: End Trace to Stop After A-Then-B Sequence
DBGCAH:DBGCAL
Trigger opcode A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Trigger opcode B
RWBEN(1)
RWB(1)
DBGT
DBGC
0
x
$82
$F0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A Then B
FIFO contents: Information from the last eight changes of flow ending when the instruction at address B
begins to execute.
This is an example of an end-trace debug run that ends when the instruction at B executes, but only after
the instruction at A has executed at least once. The sequential nature of the trigger ensures that the
trigger will occur only when you have followed a certain path through your program. In the previous begin
trace example, we may have missed a change-of-flow address (counting the trigger event itself). This
example suggests a way to use the first two change-of-flow events from that debug run to specify the
A-then-B sequence that ends this debug run. Any change-of-flow event missed during the earlier debug
run should be in the FIFO for this debug run.
Since change-of-flow addresses represent addresses where the CPU is going to try to start executing
instructions, they should always be the address of an executable instruction. In the case of program
runaway, if a change-of-flow address points at an illegal opcode, the CPU will still fetch it into its
instruction pipe and try to execute it even though the illegal opcode detect logic will intervene to force an
exception.
An end trace is used because begin-type traces cause the breakpoint to the CPU to be related to the FIFO
full condition rather than the selected trigger conditions. Since this is an end-type trace and we want a
tag-type breakpoint to the CPU, we must also specify a tag-type trigger (TRGSEL = 1). In an end trace,
if the instruction at the trigger address is a change of flow, it will be captured as the last FIFO entry for
that debug run.
7.5.8.7 Example 6: Begin Trace On Write of Data B to Address A
DBGCAH:DBGCAL
Trigger address A
RWAEN(1)
RWA(1)
1
0
DBGCBH:DBGCBL
xx:Trigger data B
RWBEN(1)
RWB(1)
DBGT
DBGC
0
x
$45
$C4
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A AND B Data (Full Mode)
FIFO contents: Information from the next eight changes of flow starting three cycles after the trigger.
This example shows a begin trace debug run that starts when the address in comparator A and the data
in the low half of comparator B both match in the same bus cycle. This is a force-type trigger so address A
can be the address of a control register or a program variable. When the FIFO has captured the next eight
change-of-flow addresses, the debug run ends, but since no CPU breakpoint is specified (BRKEN = 0),
the MCU continues to execute the application program. Typically, in this type of debug run, the host
development system would monitor the debug status register (DBGS) to determine when the debug run
was finished. The host would then read the results of the debug run from the FIFO.
This demonstrates that debugging can be done without disturbing real-time operation of an application
program. The background debug commands have a very small impact since the active background mode
commands steal a bus cycle whenever they need to access target memory. This impact is never greater
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than one bus cycle per active background mode command and background memory access commands
take at least 528 BDC clock cycles and usually have significant gaps between adjacent commands.
Variation: The A AND NOT B Data trigger mode can be used for a useful variation of this example.
Suppose you are debugging a program and you suspect some control register is being overwritten with
an unexpected value by some erroneous code. You can setup an end trace where the comparator A is
set to the address of the suspicious register and comparator B is setup with the correct data you expect
in the register. When the debug run ends, the FIFO will show the last eight changes of flow leading to the
offending instruction.
7.5.8.8 Example 7: Capture the First Eight Values Read From Address B
DBGCAH:DBGCAL
Not used
RWAEN(1)
RWA(1)
x
x
DBGCBH:DBGCBL
Trigger address B
RWBEN(1)
RWB(1)
DBGT
DBGC
1
1
$43
$C3
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: Event-Only B (Store Data)
FIFO contents: The first eight data values read from address B are stored into the low half of the FIFO
data words. The high-order eight bits of each FIFO word are unused and read as logic 0s.
This is an event-only trigger mode so the BEGIN control bit is ignored and all debug runs are treated as
begin-type traces. This mode is used to capture the data involved in a read or write access to a specific
address such as the address of a particular control register or program variable.
It would be inappropriate to set TRGSEL = 1 with this trigger mode because the trigger address is
normally not the address of an executable instruction.
7.5.8.9 Example 8: Capture Values Written to Address B After Address A Read
DBGCAH:DBGCAL
Qualifier address A
RWAEN(1)
RWA(1)
1
1
DBGCBH:DBGCBL
Trigger address B
RWBEN(1)
RWB(1)
DBGT
DBGC
1
0
$44
$CD
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: A Then Event-Only B Data (Store Data)
FIFO contents: The first eight data values written to address B after address A was read. The high-order
eight bits of each FIFO word are unused and read as logic 0s.
As in the previous example, this is an event-only trigger mode so the BEGIN control bit is ignored and all
debug runs are treated as BEGIN-type traces. In this example, address A must be detected as a qualifying
condition before the FIFO begins to capture data values for each write access to trigger address B.
Variation: If TRGSEL = 1, comparator A is qualified by opcode tracking logic so that the A trigger will not
occur until the instruction at address A is about to execute. This debug example could be used to detect
erroneous writes to a control register after the reset initialization routine was finished. To set up such a
run, store the address of one of the last instructions of the reset initialization routine in comparator A and
store the address of a selected control register in the low-order half of comparator B. After running the
application program, the host debug system can read the DBGS status register to determine whether any
values have been written to the selected control register address.
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7.5.8.10 Example 9: Trigger On Any Execution Within a Routine
DBGCAH:DBGCAL
Opcode address A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Opcode address B
RWBEN(1)
RWB(1)
DBGT
DBGC
0
x
$87
$F0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: Inside Range (A ≤ Address ≤ B)
FIFO contents: The last eight change of flow addresses before the CPU executed an instruction between
address A and address B (inclusive).
This debug run is an end trace that stops if the CPU attempts to execute any instruction within the range
specified by address A and address B. Comparator A would be set to the address of the first instruction
in the routine to be monitored, and comparator B would be set to the address of the last instruction in the
routine. TRGSEL = 1, so comparisons are qualified by opcode tracking logic. R/W is not used to qualify
either comparator. When the debug run ends, the CPU will breakpoint to active background mode. An
external debug host system can read out the contents of the FIFO to reconstruct instructions leading to
the trigger condition.
7.5.8.11 Example 10: Trigger On Any Attempt To Execute Outside FLASH
DBGCAH:DBGCAL
Opcode address A
RWAEN(1)
RWA(1)
0
x
DBGCBH:DBGCBL
Opcode address B
RWBEN(1)
RWB(1)
DBGT
DBGC
0
x
$88
$F0
1. RWAEN, RWA, RWBEN, and RWB are actually bits in DBGC. They are broken out in this table for reference.
Trigger mode: Outside Range (Address < A or Address > B)
FIFO contents: The last eight change of flow addresses before the CPU executed an instruction that was
not between address A and address B.
This example can be used to detect when a program goes outside the expected range. For example, in
a program runaway case, you could set comparator A to the address of the first instruction in the FLASH
memory and comparator B to the address of the last instruction in the FLASH memory. The debug run
will end when the CPU attempts to execute an instruction from any address outside the range of the user
program in FLASH memory. After the debug run, the FIFO can be read to reconstruct the last eight
changes of flow prior to the erroneous attempt to execute from an address outside the FLASH.
7.5.9 Hardware Breakpoints and ROM Patching
The BRKEN control bit in the DBGC register may be set to 1 to allow any of the trigger conditions
described in 7.5.6 Trigger Modes to be used to generate a hardware breakpoint request to the CPU. In
the case of ROM patching, you would never use the FIFO and you should always specify an end trace so
the CPU break request coincides with the selected trigger conditions rather than the FIFO full condition.
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
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On-Chip Debug System (DBG)
mode. If the user has taken appropriate steps to prepare for this case, it can be used to implement a form
of ROM patching.
ROM patching is a technique that allows program bugs in ROM or other non-volatile memory to be
replaced by different program instructions to repair the bug. The mechanism is based on the MCU
detecting it is about to execute an instruction at the location of a bug. Instead of executing that instruction,
hardware breakpoint logic generates a breakpoint request to the CPU. The CPU knows it is not connected
to a development system because the ENBDM control bit in BDCSCR equals 0. So instead of going to
active background mode, the CPU executes an SWI instruction. The SWI service routine fetches the
address of the repair code from some non-volatile memory location and executes that instead of the bug
code. At the end of the repair code, the stack pointer can be adjusted and an ordinary jump instruction
can return execution to a location past the original bug.
Alternatively, the repair code could alter the return address of the stack and execute an RTI to return to
a point after the original bug.
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Appendix A
Instruction Set Details
A.1 Introduction
This section contains detailed information for all HCS08 Family instructions. The instructions are arranged
in alphabetical order with the instruction mnemonic set in larger type for easy reference.
A.2 Nomenclature
This nomenclature is used in the instruction descriptions throughout this section.
Operators
()
←
&
|
⊕
×
÷
:
+
–
«
=
=
=
=
=
=
=
=
=
=
=
CPU registers
A =
CCR =
H =
X =
PC =
PCH =
PCL =
SP =
SPH =
SPL =
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)
Sign extend
Accumulator
Condition code register
Index register, higher order (most significant) eight bits
Index register, lower order (least significant) eight bits
Program counter
Program counter, higher order (most significant) eight bits
Program counter, lower order (least significant) eight bits
Stack pointer
Most significant byte of stack pointer
Least significant byte of stack pointer
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Instruction Set Details
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) eight bits are located at the address of M, and the lower-order (least
significant) eight bits are located at the next higher sequential address.
rel = The relative offset, which is the two’s complement number stored in the last byte of
machine code corresponding to a branch instruction
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)
Bit status BEFORE execution of an instruction (n = 7, 6, 5, ... 0)
For 2-byte operations such as LDHX, STHX, and CPHX, n = 15 refers to bit 15 of the 2-byte word or
bit 7 of the most significant (first) byte.
Mn = Bit n of memory location used in operation
An = Bit n of accumulator
Hn = Bit n of index register H
Xn = Bit n of index register X
bn = Bit n of the source operand (M, A, or X)
Bit status AFTER execution of an instruction
For 2-byte operations such as LDHX, STHX, and CPHX, n = 15 refers to bit 15 of the 2-byte word or
bit 7 of the most significant (first) byte.
Rn = Bit n of the result of an operation (n = 7, 6, 5, … 0)
CCR activity figure 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 eight bits of a direct address $0000–$00FF (high byte assumed to be $00)
ee = Upper eight bits of 16-bit offset
ff = Lower eight 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
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Nomenclature
Source forms
The instruction detail pages provide only essential information about assembler source forms.
Assemblers generally support a number of assembler directives, allow definition of program labels, and
have special conventions for comments. For complete information about writing source files for a
particular assembler, refer to the documentation provided by the assembler vendor.
Typically, assemblers are flexible about the use of spaces and tabs. Often, any number of spaces or tabs
can be used where a single space is shown on the glossary pages. Spaces and tabs are also normally
allowed before and after commas. When program labels are used, there must also be at least one tab or
space before all instruction mnemonics. This required space is not apparent in the source forms.
Everything in the source forms columns, except expressions in italic characters, is literal information which
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.
The definition of a legal label or expression varies from assembler to assembler. Assemblers also vary in
the way CPU registers are specified. Refer to assembler documentation for detailed information.
Recommended register designators are a, A, h, H, x, X, sp, and SP.
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 eight 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. Since the HCS08 has a 16-bit
address bus, this can be either a signed or an unsigned value.
rel — Any label or expression that refers to an address that is within –128 to +127 locations
from the next address after the last byte of object code for the current instruction. The
assembler will calculate the 8-bit signed offset and include it in the object code for this
instruction.
Cycle-by-cycle execution
This information is found in the tables at the bottom of each instruction glossary page. Entries show how
many bytes of information are accessed from different areas of memory during the course of instruction
execution. With this information and knowledge of the bus frequency, a user can determine the execution
time for any instruction in any system.
A single letter code in the column represents a single CPU cycle. There are cycle codes for each
addressing mode variation of each instruction. Simply count code letters to determine the execution time
of an instruction.
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Instruction Set Details
This list explains the cycle-by-cycle code letters:
f — Free cycle. This indicates a cycle where the CPU does not require use of the system
buses. An f cycle is always one cycle of the system bus clock.
p — Program byte access
r — 8-bit data read
s — Stack 8-bit data (push)
w — 8-bit data write
u — Unstack 8-bit data (pull)
v — Vector fetch. Vectors are always fetched as two consecutive 8-bit accesses (v v) with
the high byte first.
Address modes
INH =
IMM =
DIR =
EXT =
IX =
IX+ =
IX1 =
IX1+ =
IX2
REL
SP1
SP2
=
=
=
=
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 relative with 8-bit offset
Stack pointer relative with 16-bit offset
A.3 Convention Definitions
Set refers specifically to establishing logic level 1 on a bit or bits.
Cleared refers specifically to establishing logic level 0 on a bit or bits.
A specific bit is referred to by mnemonic and bit number. A7 is bit 7 of accumulator A. A range of bits
is referred to by mnemonic and the bit numbers that define the range. A [7:4] are bits 7 to 4 of the
accumulator.
Parentheses indicate the contents of a register or memory location, rather than the register or memory
location itself. (A) is the contents of the accumulator. In Boolean expressions, parentheses have the
traditional mathematical meaning.
A.4 Instruction Set
The following pages summarize each instruction, including operation and description, condition codes
and Boolean formulae, and a table with source forms, addressing modes, machine code, and cycles.
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Instruction Set
ADC
ADC
Add with Carry
Operation
A ← (A) + (M) + (C)
Description
Adds the contents of the C bit to the sum of the contents of A and M and places the result in A. This
operation is useful for addition of operands that are larger than eight bits.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
V: A7&M7&R7 | A7&M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise
H: A3&M3 | M3&R3 | R3&A3
Set if there was a carry from bit 3; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: A7&M7 | M7&R7 | R7&A7
Set if there was a carry from the most significant bit (MSB) of the result; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
HCS08
Cycles
Access
Detail
ADC
#opr8i
IMM
A9
ii
2
pp
ADC
opr8a
DIR
B9
dd
3
rpp
ADC
opr16a
EXT
C9
hh
ll
4
prpp
ADC
oprx16,X
IX2
D9
ee
ff
4
prpp
ff
ADC
oprx8,X
IX1
E9
ADC
,X
IX
F9
ADC
oprx16,SP
SP2
9ED9
ee
ADC
oprx8,SP
SP1
9EE9
ff
ff
3
rpp
3
rfp
5
pprpp
4
prpp
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Instruction Set Details
ADD
ADD
Add without Carry
Operation
A ← (A) + (M)
Description
Adds the contents of M to the contents of A and places the result in A
Condition Codes and Boolean Formulae
:
V
1
1
H
I
N
Z
C
—
V: A7&M7&R7 | A7&M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise
H: A3&M3 | M3&R3 | R3&A3
Set if there was a carry from bit 3; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: A7&M7 | M7&R7 | R7&A7
Set if there was a carry from the MSB of the result; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
ADD
#opr8i
IMM
AB
ADD
opr8a
DIR
BB
ADD
opr16a
EXT
CB
hh
ll
4
prpp
ADD
oprx16,X
IX2
DB
ee
ff
4
prpp
ADD
oprx8,X
IX1
EB
ff
3
rpp
ADD
,X
IX
FB
3
rfp
ADD
oprx16,SP
SP2
9EDB
ee
5
pprpp
ADD
oprx8,SP
SP1
9EEB
ff
4
prpp
Opcode
HCS08
Cycles
Access
Detail
ii
2
pp
dd
3
rpp
Operand(s)
ff
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Instruction Set
AIS
AIS
Add Immediate Value (Signed) to Stack Pointer
Operation
SP ← (SP) + (16 « M)
Description
Adds the immediate operand to the stack pointer (SP). The immediate value is an 8-bit two’s
complement signed operand. The 8-bit operand is sign-extended to 16 bits prior to the addition. The
AIS instruction can be used to create and remove a stack frame buffer that is used to store temporary
variables.
This instruction does not affect any condition code bits so status information can be passed to or from
a subroutine or C function and allocation or deallocation of space for local variables will not disturb
that status information.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycle, and Access Detail
AIS
Source
Form
Addr.
Mode
#opr8i
IMM
Machine Code
Opcode
A7
Operand(s)
ii
HCS08
Cycles
Access
Detail
2
pp
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Instruction Set Details
AIX
AIX
Add Immediate Value (Signed) to Index Register
Operation
H:X ← (H:X) + (16 « M)
Description
Adds an immediate operand to the 16-bit index register, formed by the concatenation of the H and X
registers. The immediate operand is an 8-bit two’s complement signed offset. The 8-bit operand is
sign-extended to 16 bits prior to the addition.
This instruction does not affect any condition code bits so index register pointer calculations do not
disturb the surrounding code which may rely on the state of CCR status bits.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
AIX
Source
Form
Addr.
Mode
#opr8i
IMM
Machine Code
Opcode
AF
Operand(s)
ii
HCS08
Cycles
Access
Detail
2
pp
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Instruction Set
AND
AND
Logical AND
Operation
A ← (A) & (M)
Description
Performs the logical AND between the contents of A and the contents of M and places the result in A.
Each bit of A after the operation will be the logical AND of the corresponding bits of M and of A before
the operation.
Condition Codes and Boolean Formulae
:
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
AND
#opr8i
IMM
A4
ii
2
pp
AND
opr8a
DIR
B4
dd
3
rpp
AND
opr16a
EXT
C4
hh
ll
4
prpp
AND
oprx16,X
IX2
D4
ee
ff
4
prpp
AND
oprx8,X
IX1
E4
ff
AND
,X
IX
F4
AND
oprx16,SP
SP2
9ED4
ee
AND
oprx8,SP
SP1
9EE4
ff
Opcode
Operand(s)
ff
HCS08
Cycles
Access
Detail
3
rpp
3
rfp
5
pprpp
4
prpp
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205
Instruction Set Details
ASL
ASL
Arithmetic Shift Left
(Same as LSL)
Operation
C
b7
—
—
—
—
—
—
b0
0
Description
Shifts all bits of A, X, or M one place to the left. Bit 0 is loaded with a 0. The C bit in the CCR is loaded
from the most significant bit of A, X, or M. This is mathematically equivalent to multiplication by two.
The V bit indicates whether the sign of the result has changed.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: R7⊕b7
Set if the exclusive-OR of the resulting N and C flags is 1; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: b7
Set if, before the shift, the MSB of A, X, or M was set; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr
Mode
opr8a
DIR
38
ASLA
INH (A)
ASLX
INH (X)
ASL
Machine Code
HCS08
Cycles
Access
Detail
5
rfwpp
48
1
p
58
1
p
5
rfwpp
4
rfwp
6
prfwpp
Opcode
ASL
oprx8,X
IX1
68
ASL
,X
IX
78
ASL
oprx8,SP
SP1
9E68
Operand(s)
dd
ff
ff
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206
Freescale Semiconductor
Instruction Set
ASR
ASR
Arithmetic Shift Right
Operation
b7
—
—
—
—
—
—
—
b0
C
Description
Shifts all bits of A, X, or M one place to the right. Bit 7 is held constant. Bit 0 is loaded into the C bit of
the CCR. This operation effectively divides a two’s complement value by 2 without changing its sign.
The carry bit can be used to round the result.
Condition Codes and Boolean Formulae
:
V
1
1
H
I
N
Z
C
—
—
V: R7⊕b0
Set if the exclusive-OR of the resulting N and C flags is 1; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: b0
Set if, before the shift, the LSB of A, X, or M was set; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
ASR
Machine Code
Opcode
Operand(s)
Access
Detail
DIR
37
5
rfwpp
INH (A)
47
1
p
ASRX
INH (X)
57
1
p
IX1
67
5
rfwpp
oprx8,X
ASR
,X
ASR
oprx8,SP
IX
SP1
dd
HCS08
Cycles
ASRA
ASR
opr8a
Addr.
Mode
ff
77
9E67
ff
4
rfwp
6
prfwpp
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207
Instruction Set Details
BCC
BCC
Branch if Carry Bit Clear
(Same as BHS)
Operation
If (C) = 0, PC ← (PC) + $0002 + rel
Simple branch
Description
Tests state of C bit in CCR and causes a branch if C is clear. BCC can be used after shift or rotate
instructions or to check for overflow after operations on unsigned numbers. See the BRA instruction
for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BCC
rel
Addr.
Mode
REL
Machine Code
Opcode
24
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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208
Freescale Semiconductor
Instruction Set
BCLR n
BCLR n
Clear Bit n in Memory
Operation
Mn ← 0
Description
Clear bit n (n = 7, 6, 5, … 0) in location M. All other bits in M are unaffected. In other words, M can be
any random-access memory (RAM) or input/output (I/O) register address in the $0000 to $00FF area
of memory. (Direct addressing mode is used to specify the address of the operand.) This instruction
reads the specified 8-bit location, modifies the specified bit, and then writes the modified 8-bit value
back to the memory location.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
BCLR
0,opr8a
Addr.
Mode
DIR (b0)
Machine Code
Opcode
11
Operand(s)
dd
HCS08
Cycles
Access
Detail
5
rfwpp
BCLR
1,opr8a
DIR (b1)
13
dd
5
rfwpp
BCLR
2,opr8a
DIR (b2)
15
dd
5
rfwpp
BCLR
3,opr8a
DIR (b3)
17
dd
5
rfwpp
BCLR
4,opr8a
DIR (b4)
19
dd
5
rfwpp
BCLR
5,opr8a
DIR (b5)
1B
dd
5
rfwpp
BCLR
6,opr8a
DIR (b6)
1D
dd
5
rfwpp
BCLR
7,opr8a
DIR (b7)
1F
dd
5
rfwpp
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209
Instruction Set Details
BCS
BCS
Branch if Carry Bit Set
(Same as BLO)
Operation
If (C) = 1, PC ← (PC) + $0002 + rel
Simple branch
Description
Tests the state of the C bit in the CCR and causes a branch if C is set. BCS can be used after shift or
rotate instructions or to check for overflow after operations on unsigned numbers. See the BRA
instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BCS
rel
Addr.
Mode
REL
Machine Code
Opcode
25
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BEQ
BEQ
Branch if Equal
Operation
If (Z) = 1, PC ← (PC) + $0002 + rel
Simple branch; may be used with signed or unsigned operations
Description
Tests the state of the Z bit in the CCR and causes a branch if Z is set. Compare instructions perform
a subtraction with two operands and produce an internal result without changing the original
operands. If the two operands were equal, the internal result of the subtraction for the compare will be
zero so the Z bit will be equal to one and the BEQ will cause a branch.
This instruction can also be used after a load or store without having to do a separate test or compare
on the loaded value. See the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BEQ
rel
Addr.
Mode
REL
Machine Code
Opcode
27
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
211
Instruction Set Details
BGE
BGE
Branch if Greater Than or Equal To
Operation
If (N ⊕ V) = 0, PC ← (PC) + $0002 + rel
For signed two’s complement values if (Accumulator) ≥ (Memory), then branch
Description
If the BGE instruction is executed immediately after execution of a CMP, CPHX, CPX, SBC, or SUB
instruction, the branch occurs if and only if the two’s complement number in the A, X, or H:X register
was greater than or equal to the two’s complement number in memory.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BGE
rel
Addr.
Mode
REL
Machine Code
Opcode
90
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BGND
BGND
Background
Operation
Enter active background debug mode (if allowed by ENBDM = 1)
Description
This instruction is used to establish software breakpoints during debug by replacing a user opcode
with this opcode. BGND causes the user program to stop and the CPU enters active background
mode (provided it has been enabled previously by a serial WRITE_CONTROL command from a host
debug pod). The CPU remains in active background mode until the debug host sends a serial GO,
TRACE1, or TAGGO command to return to the user program. This instruction is never used in normal
user application programs. If the ENBDM control bit in the BDC status/control register is clear, BGND
is treated as an illegal opcode.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BGND
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
82
HCS08
Cycles
Access
Detail
5+
fp...ppp
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Freescale Semiconductor
213
Instruction Set Details
BGT
BGT
Branch if Greater Than
Operation
If (Z) | (N ⊕ V) = 0, PC ← (PC) + $0002 + rel
For signed two’s complement values if (Accumulator) > (Memory), then branch
Description
If the BGT instruction is executed immediately after execution of a CMP, CPHX, CPX, SBC, or SUB
instruction, the branch will occur if and only if the two’s complement number in the A, X, or H:X register
was greater than the two’s complement number in memory.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BGT
rel
Addr.
Mode
REL
Machine Code
Opcode
92
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BHCC
BHCC
Branch if Half Carry Bit Clear
Operation
If (H) = 0, PC ← (PC) + $0002 + rel
Description
Tests the state of the H bit in the CCR and causes a branch if H is clear. This instruction is used in
algorithms involving BCD numbers that were originally written for the M68HC05 or M68HC08 devices.
The DAA instruction in the HCS08 simplifies operations on BCD numbers so BHCC and BHCS should
not be needed in new programs. See the BRA instruction for further details of the execution of the
branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
BHCC
Source
Form
Addr.
Mode
rel
REL
Machine Code
Opcode
28
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
215
Instruction Set Details
BHCS
BHCS
Branch if Half Carry Bit Set
Operation
If (H) = 1, PC ← (PC) + $0002 + rel
Description
Tests the state of the H bit in the CCR and causes a branch if H is set. This instruction is used in
algorithms involving BCD numbers that were originally written for the M68HC05 or M68HC08 devices.
The DAA instruction in the HCS08 simplifies operations on BCD numbers so BHCC and BHCS should
not be needed in new programs. See the BRA instruction for further details of the execution of the
branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
BHCS
Source
Form
Addr.
Mode
rel
REL
Machine Code
Opcode
29
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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216
Freescale Semiconductor
Instruction Set
BHI
BHI
Branch if Higher
Operation
If (C) | (Z) = 0, PC ← (PC) + $0002 + rel
For unsigned values, if (Accumulator) > (Memory), then branch
Description
Causes a branch if both C and Z are cleared. If the BHI instruction is executed immediately after
execution of a CMP, CPHX, CPX, SBC, or SUB instruction, the branch will occur if the unsigned binary
number in the A, X, or H:X register was greater than unsigned binary number in memory. Generally
not useful after CLR, COM, DEC, INC, LDA, LDHX, LDX, STA, STHX, STX, or TST because these
instructions do not affect the carry bit in the CCR. See the BRA instruction for details of the execution
of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BHI
rel
Addr.
Mode
REL
Machine Code
Opcode
22
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
217
Instruction Set Details
BHS
BHS
Branch if Higher or Same
(Same as BCC)
Operation
If (C) = 0, PC ← (PC) + $0002 + rel
For unsigned values, if (Accumulator) ≥ (Memory), then branch
Description
If the BHS instruction is executed immediately after execution of a CMP, CPHX, CPX, SBC, or SUB
instruction, the branch will occur if the unsigned binary number in the A, X, or H:X register was greater
than or equal to the unsigned binary number in memory. Generally not useful after CLR, COM, DEC,
INC, LDA, LDHX, LDX, STA, STHX, STX, or TST because these instructions do not affect the carry
bit in the CCR. See the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BHS
rel
Addr.
Mode
REL
Machine Code
Opcode
24
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
218
Freescale Semiconductor
Instruction Set
BIH
BIH
Branch if IRQ Pin High
Operation
If IRQ pin = 1, PC ← (PC) + $0002 + rel
Description
Tests the state of the external interrupt pin and causes a branch if the pin is high. See the BRA
instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BIH
rel
Addr.
Mode
REL
Machine Code
Opcode
2F
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
219
Instruction Set Details
BIL
BIL
Branch if IRQ Pin Low
Operation
If IRQ pin = 0, PC ← (PC) + $0002 + rel
Description
Tests the state of the external interrupt pin and causes a branch if the pin is low. See the BRA
instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BIL
rel
Addr.
Mode
REL
Machine Code
Opcode
2E
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BIT
BIT
Bit Test
Operation
(A) & (M)
Description
Performs the logical AND comparison of the contents of A and the contents of M and modifies the
condition codes accordingly. Neither the contents of A nor M are altered. (Each bit of the result of the
AND would be the logical AND of the corresponding bits of A and M.)
This instruction is typically used to see if a particular bit, or any of several bits, in a byte are 1s. A mask
value is prepared with 1s in any bit positions that are to be checked. This mask may be in accumulator
A or memory and the unknown value to be checked will be in memory or the accumulator A,
respectively. After the BIT instruction, a BNE instruction will branch if any bits in the tested location
that correspond to 1s in the mask were 1s.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
BIT
#opr8i
IMM
A5
ii
2
pp
BIT
opr8a
DIR
B5
dd
3
rpp
BIT
opr16a
EXT
C5
hh
ll
4
prpp
BIT
oprx16,X
IX2
D5
ee
ff
4
prpp
BIT
oprx8,X
IX1
E5
ff
3
rpp
BIT
,X
IX
F5
3
rfp
BIT
oprx16,SP
SP2
9ED5
ee
5
pprpp
BIT
oprx8,SP
SP1
9EE5
ff
4
prpp
Opcode
Operand(s)
ff
HCS08
Cycles
Access
Detail
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Freescale Semiconductor
221
Instruction Set Details
BLE
BLE
Branch if Less Than or Equal To
Operation
If (Z) | (N ⊕ V) = 1, PC ← (PC) + $0002 + rel
For signed two’s complement numbers if (Accumulator) ≤ (Memory), then branch
Description
If the BLE instruction is executed immediately after execution of a CMP, CPHX, CPX, SBC, or SUB
instruction, the branch will occur if and only if the two’s complement in the A, X, or H:X register was
less than or equal to the two’s complement number in memory.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BLE
rel
Addr.
Mode
REL
Machine Code
Opcode
93
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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222
Freescale Semiconductor
Instruction Set
BLO
BLO
Branch if Lower
Operation
If (C) = 1, PC ← (PC) + $0002 + rel
For unsigned values, if (Accumulator) < (Memory), then branch
Description
If the BLO instruction is executed immediately after execution of a CMP, CPHX, CPX, SBC, or SUB
instruction, the branch will occur if the unsigned binary number in the A, X, or H:X register was less
than the unsigned binary number in memory. Generally not useful after CLR, COM, DEC, INC, LDA,
LDHX, LDX, STA, STHX, STX, or TST because these instructions do not affect the carry bit in the
CCR. See the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BLO
rel
Addr.
Mode
REL
Machine Code
Opcode
25
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
223
Instruction Set Details
BLS
BLS
Branch if Lower or Same
Operation
If (C) | (Z) = 1, PC ← (PC) + $0002 + rel
For unsigned values, if (Accumulator) ≤ (Memory), then branch
Description
Causes a branch if (C is set) or (Z is set). If the BLS instruction is executed immediately after execution
of a CMP, CPHX, CPX, SBC, or SUB instruction, the branch will occur if and only if the unsigned
binary number in the A, X, or H:X register was less than or equal to the unsigned binary number in
memory. Generally not useful after CLR, COM, DEC, INC, LDA, LDHX, LDX, STA, STHX, STX, or
TST because these instructions do not affect the carry bit in the CCR. See the BRA instruction for
further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycle, and Access Detail
Source
Form
BLS
rel
Addr.
Mode
REL
Machine Code
Opcode
23
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BLT
BLT
Branch if Less Than
(Signed Operands)
Operation
If (N ⊕ V) = 1, PC ← (PC) + $0002 + rel
For signed two’s complement numbers if (Accumulator) < (Memory), then branch
Description
If the BLT instruction is executed immediately after execution of a CMP, CPHX, CPX, SBC, or SUB
instruction, the branch will occur if and only if the two’s complement number in the A, X, or H:X register
was less than the two’s complement number in memory. See the BRA instruction for further details of
the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BLT
rel
Addr.
Mode
REL
Machine Code
Opcode
91
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
225
Instruction Set Details
BMC
BMC
Branch if Interrupt Mask Clear
Operation
If (I) = 0, PC ← (PC) + $0002 + rel
Description
Tests the state of the I bit in the CCR and causes a branch if I is clear (if interrupts are enabled). See
the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BMC
rel
Addr.
Mode
REL
Machine Code
Opcode
2C
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Instruction Set
BMI
BMI
Branch if Minus
Operation
If (N) = 1, PC ← (PC) + $0002 + rel
Simple branch; may be used with signed or unsigned operations
Description
Tests the state of the N bit in the CCR and causes a branch if N is set.
Simply loading or storing A, X, or H:X will cause the N condition code bit to be set or cleared to match
the most significant bit of the value loaded or stored. The BMI instruction can be used after such a
load or store without having to do a separate test or compare instruction before the conditional branch.
See the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BMI
rel
Addr.
Mode
REL
Machine Code
Opcode
2B
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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227
Instruction Set Details
BMS
BMS
Branch if Interrupt Mask Set
Operation
If (I) = 1, PC ← (PC) + $0002 + rel
Description
Tests the state of the I bit in the CCR and causes a branch if I is set (if interrupts are disabled). See
BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BMS
rel
Addr.
Mode
REL
Machine Code
Opcode
2D
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BNE
BNE
Branch if Not Equal
Operation
If (Z) = 0, PC ← (PC) + $0002 + rel
Simple branch, may be used with signed or unsigned operations
Description
Tests the state of the Z bit in the CCR and causes a branch if Z is clear
Following a compare or subtract instruction, the branch will occur if the arguments were not equal.
This instruction can also be used after a load or store without hav ing to do a separate test or compare
on the loaded value. See the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BNE
rel
Addr.
Mode
REL
Machine Code
Opcode
26
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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229
Instruction Set Details
BPL
BPL
Branch if Plus
Operation
If (N) = 0, PC ← (PC) + $0002 + rel
Simple branch
Description
Tests the state of the N bit in the CCR and causes a branch if N is clear
Simply loading or storing A, X, or H:X will cause the N condition code bit to be set or cleared to match
the most significant bit of the value loaded or stored. The BPL instruction can be used after such a
load or store without having to do a separate test or compare instruction before the conditional branch.
See the BRA instruction for further details of the execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BPL
rel
Addr.
Mode
REL
Machine Code
Opcode
2A
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BRA
BRA
Branch Always
Operation
PC ← (PC) + $0002 + rel
Description
Performs an unconditional branch to the address given in the foregoing formula. In this formula, rel is
the two’s-complement relative offset in the last byte of machine code for the instruction and (PC) is
the address of the opcode for the branch instruction.
A source program specifies the destination of a branch instruction by its absolute address, either as
a numerical value or as a symbol or expression which can be numerically evaluated by the assembler.
The assembler calculates the 8-bit relative offset rel from this absolute address and the current value
of the location counter.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BRA
rel
Addr.
Mode
REL
Machine Code
Opcode
20
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
The table on the facing page is a summary of all branch instructions.
The BRA description continues next page.
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231
Instruction Set Details
BRA
BRA
Branch Always
(Continued)
Branch Instruction Summary
Table A-1 is a summary of all branch instructions.
Table A-1. Branch Instruction Summary
Branch
Complementary Branch
Type
Test
Boolean
Mnemonic Opcode
r>m
(Z) | (N⊕V)=0
BGT
92
r≤m
BLE
93
Signed
r≥m
(N⊕V)=0
BGE
90
r<m
BLT
91
Signed
r=m
(Z)=1
BEQ
27
r≠m
BNE
26
Signed
r≤m
(Z) | (N⊕V)=1
BLE
93
r>m
BGT
92
Signed
r<m
(N⊕V)=1
BLT
91
r≥m
BGE
90
Signed
r>m
(C) | (Z)=0
BHI
22
r≤m
BLS
23
Unsigned
r≥m
(C)=0
BHS/BCC
24
r<m
BLO/BCS
25
Unsigned
r=m
(Z)=1
BEQ
27
r≠m
BNE
26
Unsigned
r≤m
(C) | (Z)=1
BLS
23
r>m
BHI
22
Unsigned
r<m
(C)=1
BLO/BCS
25
r≥m
BHS/BCC
24
Unsigned
Carry
(C)=1
BCS
25
No carry
BCC
24
Simple
result=0
(Z)=1
BEQ
27
result≠0
BNE
26
Simple
Negative
(N)=1
BMI
2B
Plus
BPL
2A
Simple
I mask
(I)=1
BMS
2D
I mask=0
BMC
2C
Simple
H-Bit
(H)=1
BHCS
29
H=0
BHCC
28
Simple
IRQ high
—
BIH
2F
—
BIL
2E
Simple
Always
—
BRA
20
Never
BRN
21
Uncond.
r = register: A, X, or H:X (for CPHX instruction)
Test
Mnemonic Opcode
m = memory operand
During program execution, if the tested condition is true, the two’s complement offset is sign-extended
to a 16-bit value which is added to the current program counter. This causes program execution to
continue at the address specified as the branch destination. If the tested condition is not true, the
program simply continues to the next instruction after the branch.
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Freescale Semiconductor
Instruction Set
BRCLR n
BRCLR n
Branch if Bit n in Memory Clear
Operation
If bit n of M = 0, PC ← (PC) + $0003 + rel
Description
Tests bit n (n = 7, 6, 5, … 0) of location M and branches if the bit is clear. M can be any RAM or I/O
register address in the $0000 to $00FF area of memory because direct addressing mode is used to
specify the address of the operand.
The C bit is set to the state of the tested bit. When used with an appropriate rotate instruction, BRCLR
n provides an easy method for performing serial-to-parallel conversions.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
—
—
—
—
C: Set if Mn = 1; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
HCS08
Cycles
Access
Detail
BRCLR
0,opr8a,rel
DIR (b0)
01
dd
rr
5
rpppp
BRCLR
1,opr8a,rel
DIR (b1)
03
dd
rr
5
rpppp
BRCLR
2,opr8a,rel
DIR (b2)
05
dd
rr
5
rpppp
BRCLR
3,opr8a,rel
DIR (b3)
07
dd
rr
5
rpppp
BRCLR
4,opr8a,rel
DIR (b4)
09
dd
rr
5
rpppp
BRCLR
5,opr8a,rel
DIR (b5)
0B
dd
rr
5
rpppp
BRCLR
6,opr8a,rel
DIR (b6)
0D
dd
rr
5
rpppp
BRCLR
7,opr8a,rel
DIR (b7)
0F
dd
rr
5
rpppp
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233
Instruction Set Details
BRN
BRN
Branch Never
Operation
PC ← (PC) + $0002
Description
Never branches. In effect, this instruction can be considered a 2-byte no operation (NOP) requiring
three cycles for execution. Its inclusion in the instruction set provides a complement for the BRA
instruction. The BRN instruction is useful during program debugging to negate the effect of another
branch instruction without disturbing the offset byte.
This instruction can be useful in instruction-based timing delays. Instruction-based timing delays are
usually discouraged because such code is not portable to systems with different clock speeds.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BRN
rel
Addr.
Mode
REL
Machine Code
Opcode
21
Operand(s)
rr
HCS08
Cycles
Access
Detail
3
ppp
See the BRA instruction for a summary of all branches and their complements.
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Freescale Semiconductor
Instruction Set
BRSET n
BRSET n
Branch if Bit n in Memory Set
Operation
If bit n of M = 1, PC ← (PC) + $0003 + rel
Description
Tests bit n (n = 7, 6, 5, … 0) of location M and branches if the bit is set. M can be any RAM or I/O
register address in the $0000 to $00FF area of memory because direct addressing mode is used to
specify the address of the operand.
The C bit is set to the state of the tested bit. When used with an appropriate rotate instruction, BRSET
n provides an easy method for performing serial-to-parallel conversions.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
—
—
—
—
C: Set if Mn = 1; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
HCS08
Cycles
Access
Detail
BRSET
0,opr8a,rel
DIR (b0)
00
dd
rr
5
rpppp
BRSET
1,opr8a,rel
DIR (b1)
02
dd
rr
5
rpppp
BRSET
2,opr8a,rel
DIR (b2)
04
dd
rr
5
rpppp
BRSET
3,opr8a,rel
DIR (b3)
06
dd
rr
5
rpppp
BRSET
4,opr8a,rel
DIR (b4)
08
dd
rr
5
rpppp
BRSET
5,opr8a,rel
DIR (b5)
0A
dd
rr
5
rpppp
BRSET
6,opr8a,rel
DIR (b6)
0C
dd
rr
5
rpppp
BRSET
7,opr8a,rel
DIR (b7)
0E
dd
rr
5
rpppp
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235
Instruction Set Details
BSET n
BSET n
Set Bit n in Memory
Operation
Mn ← 1
Description
Set bit n (n = 7, 6, 5, … 0) in location M. All other bits in M are unaffected. M can be any RAM or I/O
register address in the $0000 to $00FF area of memory because direct addressing mode is used to
specify the address of the operand. This instruction reads the specified 8-bit location, modifies the
specified bit, and then writes the modified 8-bit value back to the memory location.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
HCS08
Cycles
Access
Detail
BSET
0,opr8a
DIR (b0)
10
dd
5
rfwpp
BSET
1,opr8a
DIR (b1)
12
dd
5
rfwpp
BSET
2,opr8a
DIR (b2)
14
dd
5
rfwpp
BSET
3,opr8a
DIR (b3)
16
dd
5
rfwpp
BSET
4,opr8a
DIR (b4)
18
dd
5
rfwpp
BSET
5,opr8a
DIR (b5)
1A
dd
5
rfwpp
BSET
6,opr8a
DIR (b6)
1C
dd
5
rfwpp
BSET
7,opr8a
DIR (b7)
1E
dd
5
rfwpp
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Freescale Semiconductor
Instruction Set
BSR
BSR
Branch to Subroutine
Operation
PC ← (PC) + $0002
Push (PCL); SP ← (SP) – $0001
Push (PCH); SP ← (SP) – $0001
PC ← (PC) + rel
Advance PC to return address
Push low half of return address
Push high half of return address
Load PC with start address of requested subroutine
Description
The program counter is incremented by 2 from the opcode address (so it points to the opcode of the
next instruction which will be the return address). The least significant byte of the contents of the
program counter (low-order return address) is pushed onto the stack. The stack pointer is then
decremented by 1. The most significant byte of the contents of the program counter (high-order return
address) is pushed onto the stack. The stack pointer is then decremented by 1. A branch then occurs
to the location specified by the branch offset. See the BRA instruction for further details of the
execution of the branch.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
BSR
rel
Addr.
Mode
REL
Machine Code
Opcode
AD
Operand(s)
rr
HCS08
Cycles
Access
Detail
5
ssppp
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237
Instruction Set Details
CBEQ
CBEQ
Compare and Branch if Equal
Operation
For DIR or IMM modes:
Or for IX+ mode:
Or for SP1 mode:
Or for CBEQX:
if (A) = (M), PC ← (PC) + $0003 + rel
if (A) = (M); PC ← (PC) + $0002 + rel
if (A) = (M); PC ← (PC) + $0004 + rel
if (X) = (M); PC ← (PC) + $0003 + rel
Description
CBEQ compares the operand with the accumulator (or index register for CBEQX instruction) against
the contents of a memory location and causes a branch if the register (A or X) is equal to the memory
contents. The CBEQ instruction combines CMP and BEQ for faster table lookup routines and
condition codes are not changed.
The IX+ variation of the CBEQ instruction compares the operand addressed by H:X to A and causes
a branch if the operands are equal. H:X is then incremented regardless of whether a branch is taken.
The IX1+ variation of CBEQ operates the same way except that an 8-bit offset is added to H:X to form
the effective address of the operand.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
HCS08
Cycles
Access
Detail
CBEQ
opr8a,rel
DIR
31
dd
rr
5
rpppp
CBEQA
#opr8i,rel
IMM
41
ii
rr
4
pppp
CBEQX
#opr8i,rel
IMM
51
ii
rr
4
pppp
CBEQ
oprx8,X+,rel
IX1+
61
ff
rr
5
rpppp
CBEQ
,X+,rel
IX+
71
rr
5
rfppp
CBEQ
oprx8,SP,rel
SP1
9E61
ff
6
prpppp
rr
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Freescale Semiconductor
Instruction Set
CLC
CLC
Clear Carry Bit
Operation
C bit ← 0
Description
Clears the C bit in the CCR. CLC may be used to set up the C bit prior to a shift or rotate instruction
that involves the C bit. The C bit can also be used to pass status information between a subroutine
and the calling program.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
—
—
—
—
0
C: 0
Cleared
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
CLC
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
98
HCS08
Cycles
Access
Detail
1
p
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Freescale Semiconductor
239
Instruction Set Details
CLI
CLI
Clear Interrupt Mask Bit
Operation
I bit ← 0
Description
Clears the interrupt mask bit in the CCR. When the I bit is clear, interrupts are enabled. The I bit
actually changes to zero at the end of the cycle where the CLI instruction executes. This is too late to
recognize an interrupt that arrived before or during the CLI instruction so if interrupts were previously
disabled, the next instruction after a CLI will always be executed even if there was an interrupt pending
prior to execution of the CLI instruction.
Condition Codes and Boolean Formulae
V
—
I:
1
1
H
I
N
Z
C
—
0
—
—
—
0
Cleared
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
CLI
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
9A
HCS08
Cycles
Access
Detail
1
p
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Freescale Semiconductor
Instruction Set
CLR
CLR
Clear
Operation
A ← $00
Or M ← $00
Or X ← $00
Or H ← $00
Description
The contents of memory (M), A, X, or H are replaced with zeros.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
0
1
—
V: 0
Cleared
N: 0
Cleared
Z: 1
Set
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
CLR
Source
Form
Addr.
Mode
opr8a
DIR
3F
INH (A)
CLRA
Machine Code
HCS08
Cycles
Access
Detail
5
rfwpp
4F
1
p
Opcode
Operand(s)
dd
CLRX
INH (X)
5F
1
p
CLRH
INH (H)
8C
1
p
5
rfwpp
4
rfwp
6
prfwpp
CLR
oprx8,X
IX1
6F
CLR
,X
IX
7F
CLR
oprx8,SP
SP1
9E6F
ff
ff
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241
Instruction Set Details
CMP
CMP
Compare Accumulator with Memory
Operation
(A) – (M)
Description
Compares the contents of A to the contents of M and sets the condition codes, which may then be
used for arithmetic (signed or unsigned) and logical conditional branching. The contents of both A and
M are unchanged.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: A7&M7&R7 | A7&M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise. Literally read,
an overflow condition occurs if a positive number is subtracted from a negative number with a
positive result, or, if a negative number is subtracted from a positive number with a negative
result.
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: A7&M7 | M7&R7 | R7&A7
Set if the unsigned value of the contents of memory is larger than the unsigned value of the
accumulator; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
HCS08
Cycles
Access
Detail
CMP
#opr8i
IMM
A1
ii
2
pp
CMP
opr8a
DIR
B1
dd
3
rpp
CMP
opr16a
EXT
C1
hh
ll
4
prpp
ff
4
prpp
3
rpp
3
rfp
5
pprpp
4
prpp
Opcode
Operand(s)
CMP
oprx16,X
IX2
D1
ee
CMP
oprx8,X
IX1
E1
ff
CMP
,X
IX
F1
CMP
oprx16,SP
SP2
9ED1
ee
CMP
oprx8,SP
SP1
9EE1
ff
ff
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Freescale Semiconductor
Instruction Set
COM
COM
Complement (One’s Complement)
Operation
A ← A = $FF – (A)
Or X ← X = $FF – (X)
Or M ← M = $FF – (M)
Description
Replaces the contents of A, X, or M with the one’s complement. Each bit of A, X, or M is replaced with
the complement of that bit.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
1
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: 1
Set
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
COM
opr8a
Addr.
Mode
Machine Code
Opcode
Operand(s)
Access
Detail
DIR
33
5
rfwpp
COMA
INH (A)
43
1
p
COMX
INH (X)
53
1
p
IX1
63
5
rfwpp
COM
oprx8,X
COM
,X
COM
oprx8,SP
IX
SP1
dd
HCS08
Cycles
ff
73
9E63
ff
4
rfwp
6
prfwpp
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243
Instruction Set Details
CPHX
CPHX
Compare Index Register with Memory
Operation
(H:X) – (M:M + $0001)
Description
CPHX compares index register (H:X) with the 16-bit value in memory and sets the condition codes,
which may then be used for arithmetic (signed or unsigned) and logical conditional branching. The
contents of both H:X and M:M + $0001 are unchanged.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: H7&M15&R15 | H7&M15&R15
Set if a two’s complement overflow resulted from the operation; cleared otherwise
N: R15
Set if MSB of result is 1; cleared otherwise
Z: R15&R14&R13&R12&R11&R10&R9&R8
&R7&R6&R5&R4&R3&R2&R1&R0
Set if the result is $0000; cleared otherwise
C: H7&M15 | M15&R15 | R15&H7
Set if the absolute value of the contents of memory is larger than the absolute value of the index
register; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
HCS08
Cycles
Access
Detail
prrfpp
CPHX
opr16a
EXT
3E
hh
ll
6
kk
CPHX
#opr16i
IMM
65
jj
3
ppp
CPHX
opr8a
DIR
75
dd
5
rrfpp
CPHX
oprx8,SP
SP1
9EF3
ff
6
prrfpp
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Freescale Semiconductor
Instruction Set
CPX
CPX
Compare X (Index Register Low) with Memory
Operation
(X) – (M)
Description
Compares the contents of X to the contents of M and sets the condition codes, which may then be
used for arithmetic (signed or unsigned) and logical conditional branching. The contents of both X and
M are unchanged.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: X7&M7&R7 | X7&M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise
N: R7
Set if MSB of result of the subtraction is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: X7&M7 | M7&R7 | R7&X7
Set if the unsigned value of the contents of memory is
larger than the unsigned value in the index register;
cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
CPX
#opr8i
IMM
CPX
opr8a
DIR
B3
dd
3
rpp
CPX
opr16a
EXT
C3
hh
ll
4
prpp
CPX
oprx16,X
IX2
D3
ee
ff
4
prpp
CPX
oprx8,X
IX1
E3
ff
3
rpp
CPX
,X
CPX
oprx16,SP
SP2
9ED3
ee
CPX
oprx8,SP
SP1
9EE3
ff
IX
Machine Code
Opcode
A3
Operand(s)
ii
F3
ff
HCS08
Cycles
Access
Detail
2
pp
3
rfp
5
pprpp
4
prpp
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
245
Instruction Set Details
DAA
DAA
Decimal Adjust Accumulator
Operation
(A)10
Description
Adjusts the contents of the accumulator and the state of the CCR carry bit after an ADD or ADC
operation involving binary-coded decimal (BCD) values, so that there is a correct BCD sum and an
accurate carry indication. The state of the CCR half carry bit affects operation. Refer to Table A-2 for
details of operation.
Condition Codes and Boolean Formulae
V
U
1
1
H
I
N
Z
C
—
—
V: U
Undefined
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: Set if the decimal adjusted result is greater than 99 (decimal); refer to Table A-2
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
DAA
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
72
HCS08
Cycles
Access
Detail
1
p
The DAA description continues next page.
HCS08 Family Reference Manual, Rev. 2
246
Freescale Semiconductor
Instruction Set
DAA
DAA
Decimal Adjust Accumulator (Continued)
Table A-2 shows DAA operation for all legal combinations of input operands. Columns 1–4 represent
the results of ADC or ADD operations on BCD operands. The correction factor in column 5 is added
to the accumulator to restore the result of an operation on two BCD operands to a valid BCD value
and to set or clear the C bit. All values in this table are hexadecimal.
Table A-2. DAA Function Summary
1
2
3
4
5
6
Initial
C-Bit Value
Value
of A[7:4]
Initial
H-Bit Value
Value
of A[3:0]
Correction
Factor
Corrected
C-Bit Value
0
0–9
0
0–9
00
0
0
0–8
0
A–F
06
0
0
0–9
1
0–3
06
0
0
A–F
0
0–9
60
1
0
9–F
0
A–F
66
1
0
A–F
1
0–3
66
1
1
0–2
0
0–9
60
1
1
0–2
0
A–F
66
1
1
0–3
1
0–3
66
1
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
247
Instruction Set Details
DBNZ
DBNZ
Decrement and Branch if Not Zero
Operation
A ← (A) – $01
Or M ← (M) – $01
Or X ← (X) – $01
For DIR or IX1 modes:
PC ← (PC) + $0003 + rel if (result) ≠ 0
Or for INH or IX modes: PC ← (PC) + $0002 + rel if (result) ≠ 0
Or for SP1 mode:
PC ← (PC) + $0004 + rel if (result) ≠ 0
Description
Subtract 1 from the contents of A, M, or X; then branch using the relative offset if the result of the
subtraction is not $00. DBNZX only affects the low order eight bits of the H:X index register pair; the
high-order byte (H) is not affected.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
DBNZ
DBNZA
DBNZX
Addr.
Mode
Machine Code
Opcode
Operand(s)
opr8a,rel
DIR
3B
dd
rel
INH
4B
rr
rel
INH
5B
rr
DBNZ
oprx8,X,rel
IX1
6B
ff
DBNZ
,X, rel
IX
7B
rr
DBNZ
oprx8,SP,rel
9E6B
ff
SP1
rr
rr
rr
HCS08
Cycles
Access
Detail
7
rfwpppp
4
fppp
4
fppp
7
rfwpppp
6
rfwppp
8
prfwpppp
HCS08 Family Reference Manual, Rev. 2
248
Freescale Semiconductor
Instruction Set
DEC
DEC
Decrement
Operation
A ← (A) – $01
Or X ← (X) – $01
Or M ← (M) – $01
Description
Subtract 1 from the contents of A, X, or M. The V, N, and Z bits in the CCR are set or cleared according
to the results of this operation. The C bit in the CCR is not affected; therefore, the BLS, BLO, BHS,
and BHI branch instructions are not useful following a DEC instruction.
DECX only affects the low-order byte of index register pair (H:X). To decrement the full 16-bit index
register pair (H:X), use AIX # –1.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
—
V: R7 & A7
Set if there was a two’s complement overflow as a result of the operation; cleared otherwise.
Two’s complement overflow occurs if and only if (A), (X), or (M) was $80 before the operation.
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
DEC
opr8a
Addr.
Mode
Machine Code
Opcode
Operand(s)
Access
Detail
DIR
3A
5
rfwpp
DECA
INH (A)
4A
1
p
DECX
INH (X)
5A
1
p
IX1
6A
5
rfwpp
DEC
oprx8,X
DEC
,X
DEC
oprx8,SP
IX
SP1
dd
HCS08
Cycles
ff
7A
9E6A
ff
4
rfwp
6
prfwpp
DEX is recognized by assemblers as being equivalent to DECX.
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
249
Instruction Set Details
DIV
DIV
Divide
Operation
A ← (H:A) ÷ (X); H ← Remainder
Description
Divides a 16-bit unsigned dividend contained in the concatenated registers H and A by an 8-bit divisor
contained in X. The quotient is placed in A, and the remainder is placed in H. The divisor is left
unchanged.
An overflow (quotient > $FF) or divide-by-0 sets the C bit, and the quotient and remainder are
indeterminate.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
—
—
—
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result (quotient) is $00; cleared otherwise
C: Set if a divide-by-0 was attempted or if an overflow occurred; cleared otherwise
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
DIV
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
52
HCS08
Cycles
Detail
Access
6
fffffp
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250
Freescale Semiconductor
Instruction Set
EOR
EOR
Exclusive-OR Memory with Accumulator
Operation
A ← (A ⊕ M)
Description
Performs the logical exclusive-OR between the contents of A and the contents of M and places the
result in A. Each bit of A after the operation will be the logical exclusive-OR of the corresponding bits
of M and A before the operation.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
EOR
#opr8i
IMM
EOR
opr8a
DIR
B8
dd
3
rpp
EOR
opr16a
EXT
C8
hh
ll
4
prpp
EOR
oprx16,X
IX2
D8
ee
ff
4
prpp
EOR
oprx8,X
IX1
E8
ff
3
rpp
EOR
,X
EOR
oprx16,SP
SP2
9ED8
ee
EOR
oprx8,SP
SP1
9EE8
ff
IX
Machine Code
Opcode
A8
Operand(s)
ii
F8
ff
HCS08
Cycles
Access
Detail
2
pp
3
rfp
5
pprpp
4
prpp
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
251
Instruction Set Details
INC
INC
Increment
Operation
A ← (A) + $01
Or X ← (X) + $01
Or M ← (M) + $01
Description
Add 1 to the contents of A, X, or M. The V, N, and Z bits in the CCR are set or cleared according to
the results of this operation. The C bit in the CCR is not affected; therefore, the BLS, BLO, BHS, and
BHI branch instructions are not useful following an INC instruction.
INCX only affects the low-order byte of index register pair (H:X). To increment the full 16-bit index
register pair (H:X), use AIX #1.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
—
V: A7&R7
Set if there was a two’s complement overflow as a result of the operation; cleared otherwise.
Two’s complement overflow occurs if and only if (A), (X), or (M) was $7F before the operation.
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
INC
opr8a
Addr.
Mode
Machine Code
Opcode
Operand(s)
Access
Detail
DIR
3C
5
rfwpp
INCA
INH (A)
4C
1
p
INCX
INH (X)
5C
1
p
IX1
6C
5
rfwpp
INC
oprx8,X
INC
,X
INC
oprx8,SP
IX
SP1
dd
HCS08
Cycles
ff
7C
9E6C
ff
4
rfwp
6
prfwpp
INX is recognized by assemblers as being equivalent to INCX.
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252
Freescale Semiconductor
Instruction Set
JMP
JMP
Jump
Operation
PC ← effective address
Description
A jump occurs to the instruction stored at the effective address. The effective address is obtained
according to the rules for extended, direct, or indexed addressing.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
JMP
opr8a
DIR
BC
dd
JMP
opr16a
EXT
CC
hh
Opcode
HCS08
Cycles
Access
Detail
3
ppp
ll
4
pppp
ff
4
pppp
3
ppp
3
ppp
Operand(s)
JMP
oprx16,X
IX2
DC
ee
JMP
oprx8,X
IX1
EC
ff
JMP
,X
IX
FC
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
253
Instruction Set Details
JSR
JSR
Jump to Subroutine
Operation
PC ← (PC) + n;
n = 1, 2, or 3 depending on address mode
Push (PCL); SP ← (SP) – $0001
Push low half of return address
Push (PCH); SP ← (SP) – $0001
Push high half of return address
PC ← effective address
Load PC with start address of requested subroutine
Description
The program counter is incremented by n so that it points to the opcode of the next instruction that
follows the JSR instruction (n = 1, 2, or 3 depending on the addressing mode). The PC is then pushed
onto the stack, eight bits at a time, least significant byte first. The stack pointer points to the next empty
location on the stack. A jump occurs to the instruction stored at the effective address. The effective
address is obtained according to the rules for extended, direct, or indexed addressing.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
JSR
opr8a
DIR
JSR
opr16a
EXT
CD
hh
ll
6
pssppp
JSR
oprx16,X
IX2
DD
ee
ff
6
pssppp
JSR
oprx8,X
IX1
ED
ff
5
ssppp
JSR
,X
IX
FD
5
ssppp
Opcode
BD
Operand(s)
dd
HCS08
Cycles
Access
Detail
5
ssppp
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254
Freescale Semiconductor
Instruction Set
LDA
LDA
Load Accumulator from Memory
Operation
A ← (M)
Description
Loads the contents of the specified memory location into A. The N and Z condition codes are set or
cleared according to the loaded data; V is cleared. This allows conditional branching after the load
without having to perform a separate test or compare.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
LDA
Source
Form
Addr.
Mode
#opr8i
IMM
Machine Code
Opcode
A6
Operand(s)
ii
HCS08
Cycles
Access
Detail
2
pp
LDA
opr8a
DIR
B6
dd
3
rpp
LDA
opr16a
EXT
C6
hh
ll
4
prpp
LDA
oprx16,X
IX2
D6
ee
ff
4
prpp
LDA
oprx8,X
IX1
E6
ff
3
rpp
LDA
,X
LDA
oprx16,SP
SP2
9ED6
ee
LDA
oprx8,SP
SP1
9EE6
ff
IX
F6
ff
3
rfp
5
pprpp
4
prpp
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
255
Instruction Set Details
LDHX
LDHX
Load Index Register from Memory
Operation
H:X ← (M:M + $0001)
Description
Loads the contents of the specified memory location into the index register (H:X). The N and Z
condition codes are set according to the data; V is cleared. This allows conditional branching after the
load without having to perform a separate test or compare.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R15
Set if MSB of result is 1; cleared otherwise
Z: R15&R14&R13&R12&R11&R10&R9&R8
&R7&R6&R5&R4&R3&R2&R1&R0
Set if the result is $0000; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
Opcode
Operand(s)
kk
HCS08
Cycles
Access
Detail
3
ppp
4
rrpp
5
prrpp
5
prrfp
6
pprrpp
LDHX
#opr16i
IMM
45
jj
LDHX
opr8a
DIR
55
dd
LDHX
opr16a
EXT
32
hh
LDHX
,X
IX
9EAE
LDHX
oprx16,X
IX2
9EBE
ee
LDHX
oprx8,X
IX1
9ECE
ff
5
prrpp
LDHX
oprx8,SP
SP1
9EFE
ff
5
prrpp
ll
ff
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256
Freescale Semiconductor
Instruction Set
LDX
LDX
Load X (Index Register Low) from Memory
Operation
X ← (M)
Description
Loads the contents of the specified memory location into X. The N and Z condition codes are set or
cleared according to the loaded data; V is cleared. This allows conditional branching after the load
without having to perform a separate test or compare.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
LDX
Source
Form
Addr.
Mode
#opr8i
IMM
Machine Code
Opcode
AE
Operand(s)
ii
HCS08
Cycles
Access
Detail
2
pp
LDX
opr8a
DIR
BE
dd
3
rpp
LDX
opr16a
EXT
CE
hh
ll
4
prpp
LDX
oprx16,X
IX2
DE
ee
ff
4
prpp
LDX
oprx8,X
IX1
EE
ff
3
rpp
LDX
,X
LDX
oprx16,SP
SP2
9EDE
ee
LDX
oprx8,SP
SP1
9EEE
ff
IX
FE
ff
3
rfp
5
pprpp
4
prpp
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Freescale Semiconductor
257
Instruction Set Details
LSL
LSL
Logical Shift Left
(Same as ASL)
Operation
C
b7
—
—
—
—
—
—
b0
0
Description
Shifts all bits of the A, X, or M one place to the left. Bit 0 is loaded with a 0. The C bit in the CCR is
loaded from the most significant bit of A, X, or M.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: R7⊕b7
Set if the exclusive-OR of the resulting N and C flags is 1; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: b7
Set if, before the shift, the MSB of A, X, or M was set; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
LSL
Machine Code
Opcode
Operand(s)
Access
Detail
DIR
38
5
rfwpp
INH (A)
48
1
p
LSLX
INH (X)
58
1
p
IX1
68
5
rfwpp
oprx8,X
LSL
,X
LSL
oprx8,SP
IX
SP1
dd
HCS08
Cycles
LSLA
LSL
opr8a
Addr.
Mode
ff
78
9E68
ff
4
rfwp
6
prfwpp
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258
Freescale Semiconductor
Instruction Set
LSR
LSR
Logical Shift Right
Operation
0
b7
—
—
—
—
—
—
b0
C
Description
Shifts all bits of A, X, or M one place to the right. Bit 7 is loaded with a 0. Bit 0 is shifted into the C bit.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
0
V: 0⊕b0 = b0
Set if the exclusive-OR of the resulting N and C flags is 1; cleared otherwise. Since N = 0, this
simplifies to the value of bit 0 before the shift.
N: 0
Cleared
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: b0
Set if, before the shift, the LSB of A, X, or M, was set; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
LSR
Source
Form
Addr.
Mode
opr8a
DIR
34
INH (A)
44
LSRA
LSRX
Machine Code
Opcode
INH (X)
54
LSR
oprx8,X
IX1
64
LSR
,X
IX
74
LSR
oprx8,SP
SP1
9E64
Operand(s)
dd
ff
ff
HCS08
Cycles
Access
Detail
5
rfwpp
1
p
1
p
5
rfwpp
4
rfwp
6
prfwpp
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
259
Instruction Set Details
MOV
MOV
Move
Operation
(M)Destination ← (M)Source
Description
Moves a byte of data from a source address to a destination address. Data is examined as it is moved,
and condition codes are set. Source data is not changed. The accumulator is not affected.
The four addressing modes for the MOV instruction are:
1. IMM/DIR moves an immediate byte to a direct memory location.
2. DIR/DIR moves a direct location byte to another direct location.
3. IX+/DIR moves a byte from a location addressed by H:X to a direct location. H:X is incremented
after the move.
4. DIR/IX+ moves a byte from a direct location to one addressed by H:X. H:X is incremented after
the move.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is set; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
MOV
opr8a,opr8a
Addr.
Mode
DIR/DIR
Machine Code
Opcode
4E
HCS08
Cycles
Access
Detail
dd
5
rpwpp
5
rfwpp
dd
4
pwpp
5
rfwpp
Operand(s)
dd
MOV
opr8a,X+
DIR/IX+
5E
dd
MOV
#opr8i,opr8a
IMM/DIR
6E
ii
MOV
,X+,opr8a
IX+/DIR
7E
dd
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260
Freescale Semiconductor
Instruction Set
MUL
MUL
Unsigned Multiply
Operation
X:A ← (X) × (A)
Description
Multiplies the 8-bit value in X (index register low) by the 8-bit value in the accumulator to obtain a 16-bit
unsigned result in the concatenated index register and accumulator. After the operation, X contains
the upper eight bits of the 16-bit result and A contains the lower eight bits of the result.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
0
—
—
—
0
H: 0
Cleared
C: 0
Cleared
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
MUL
Addr.
Mode
Machine Code
Opcode
INH
42
Operand(s)
HCS08
Cycles
Access
Detail
5
ffffp
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Freescale Semiconductor
261
Instruction Set Details
NEG
NEG
Negate (Two’s Complement)
Operation
A ← – (A)
Or X ← – (X)
Or M ← – (M);
this is equivalent to subtracting A, X, or M from $00
Description
Replaces the contents of A, X, or M with its two’s complement. Note that the value $80 is left
unchanged.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise. Overflow will
occur only if the operand is $80 before the operation.
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: R7|R6|R5|R4|R3|R2|R1|R0
Set if there is a borrow in the implied subtraction from 0; cleared otherwise. The C bit will be set
in all cases except when the contents of A, X, or M was $00 prior to the NEG operation.
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
NEG
opr8a
Addr.
Mode
Machine Code
Opcode
Operand(s)
Access
Detail
5
rfwpp
DIR
30
NEGA
INH (A)
40
1
p
NEGX
INH (X)
50
1
p
NEG
oprx8,X
IX1
60
NEG
,X
IX
70
NEG
oprx8,SP
SP1
9E60
dd
HCS08
Cycles
ff
ff
5
rfwpp
4
rfwp
6
prfwpp
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Instruction Set
NOP
NOP
No Operation
Operation
Uses one bus cycle
Description
This is a single-byte instruction that does nothing except to consume one CPU clock cycle while the
program counter is advanced to the next instruction. No register or memory contents are affected by
this instruction.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
NOP
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
9D
HCS08
Cycles
Access
Detail
1
p
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263
Instruction Set Details
NSA
NSA
Nibble Swap Accumulator
Operation
A ← (A[3:0]:A[7:4])
Description
Swaps upper and lower nibbles (4 bits) of the accumulator. The NSA instruction is used for more
efficient storage and use of binary-coded decimal operands.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
NSA
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
62
HCS08
Cycles
Access
Detail
1
p
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Freescale Semiconductor
Instruction Set
ORA
ORA
Inclusive-OR Accumulator and Memory
Operation
A ← (A) | (M)
Description
Performs the logical inclusive-OR between the contents of A and the contents of M and places the
result in A. Each bit of A after the operation will be the logical inclusive-OR of the corresponding bits
of M and A before the operation.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
ORA
#opr8i
IMM
ORA
opr8a
DIR
BA
dd
3
rpp
ORA
opr16a
EXT
CA
hh
ll
4
prpp
ORA
oprx16,X
IX2
DA
ee
ff
4
prpp
ORA
oprx8,X
IX1
EA
ff
3
rpp
IX
Machine Code
Opcode
AA
Operand(s)
ii
ORA
,X
ORA
oprx16,SP
SP2
9EDA
FA
ee
ORA
oprx8,SP
SP1
9EEA
ff
ff
HCS08
Cycles
Access
Detail
2
pp
3
rfp
5
pprpp
4
prpp
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265
Instruction Set Details
PSHA
PSHA
Push Accumulator onto Stack
Operation
Push (A); SP ← (SP) – $0001
Description
The contents of A are pushed onto the stack at the address contained in the stack pointer. The stack
pointer is then decremented to point to the next available location in the stack. The contents of A
remain unchanged.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
PSHA
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
87
HCS08
Cycles
Access
Detail
2
sp
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Freescale Semiconductor
Instruction Set
PSHH
PSHH
Push H (Index Register High) onto Stack
Operation
Push (H); SP ← (SP) – $0001
Description
The contents of H are pushed onto the stack at the address contained in the stack pointer. The stack
pointer is then decremented to point to the next available location in the stack. The contents of H
remain unchanged.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
PSHH
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
8B
HCS08
Cycles
Access
Detail
2
sp
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267
Instruction Set Details
PSHX
PSHX
Push X (Index Register Low) onto Stack
Operation
Push (X); SP ← (SP) – $0001
Description
The contents of X are pushed onto the stack at the address contained in the stack pointer (SP). SP is
then decremented to point to the next available location in the stack. The contents of X remain
unchanged.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
PSHX
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
89
HCS08
Cycles
Access
Detail
2
sp
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Instruction Set
PULA
PULA
Pull Accumulator from Stack
Operation
SP ← (SP + $0001); pull (A)
Description
The stack pointer (SP) is incremented to address the last operand on the stack. The accumulator is
then loaded with the contents of the address pointed to by SP.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
PULA
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
86
HCS08
Cycles
Access
Detail
3
ufp
HCS08 Family Reference Manual, Rev. 2
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269
Instruction Set Details
PULH
PULH
Pull H (Index Register High) from Stack
Operation
SP ← (SP + $0001); pull (H)
Description
The stack pointer (SP) is incremented to address the last operand on the stack. H is then loaded with
the contents of the address pointed to by SP.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
PULH
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
8A
HCS08
Cycles
Access
Detail
3
ufp
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Instruction Set
PULX
PULX
Pull X (Index Register Low) from Stack
Operation
SP ← (SP + $0001); pull (X)
Description
The stack pointer (SP) is incremented to address the last operand on the stack. X is then loaded with
the contents of the address pointed to by SP.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
PULX
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
88
HCS08
Cycles
Access
Detail
3
ufp
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271
Instruction Set Details
ROL
ROL
Rotate Left through Carry
Operation
C
b7
—
—
—
—
—
—
—
b0
Description
Shifts all bits of A, X, or M one place to the left. Bit 0 is loaded from the C bit. The C bit is loaded from
the most significant bit of A, X, or M. The rotate instructions include the carry bit to allow extension of
the shift and rotate instructions to multiple bytes. For example, to shift a 24-bit value left one bit, the
sequence (ASL LOW, ROL MID, ROL HIGH) could be used, where LOW, MID, and HIGH refer to the
low-order, middle, and high-order bytes of the 24-bit value, respectively.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: R7 ⊕ b7
Set if the exclusive-OR of the resulting N and C flags is 1; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: b7
Set if, before the rotate, the MSB of A, X, or M was set; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
opr8a
DIR
39
ROLA
INH (A)
ROLX
INH (X)
ROL
Machine Code
HCS08
Cycles
Access
Detail
5
rfwpp
49
1
p
59
1
p
5
rfwpp
4
rfwp
6
prfwpp
Opcode
ROL
oprx8,X
IX1
69
ROL
,X
IX
79
ROL
oprx8,SP
SP1
9E69
Operand(s)
dd
ff
ff
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Instruction Set
ROR
ROR
Rotate Right through Carry
Operation
b7
—
—
—
—
—
—
—
b0
C
Description
Shifts all bits of A, X, or M one place to the right. Bit 7 is loaded from the C bit. Bit 0 is shifted into the
C bit. The rotate instructions include the carry bit to allow extension of the shift and rotate instructions
to multiple bytes. For example, to shift a 24-bit value right one bit, the sequence (LSR HIGH, ROR
MID, ROR LOW) could be used, where LOW, MID, and HIGH refer to the low-order, middle, and
high-order bytes of the 24-bit value, respectively.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: R7 ⊕ b0
Set if the exclusive-OR of the resulting N and C flags is 1; cleared otherwise
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: b0
Set if, before the shift, the LSB of A, X, or M was set; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
ROR
opr8a
Addr.
Mode
Machine Code
Opcode
Operand(s)
Access
Detail
5
rfwpp
DIR
36
RORA
INH (A)
46
1
p
RORX
INH (X)
56
1
p
5
rfwpp
4
rfwp
6
prfwpp
ROR
oprx8,X
IX1
66
ROR
,X
IX
76
ROR
oprx8,SP
SP1
9E66
dd
HCS08
Cycles
ff
ff
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273
Instruction Set Details
RSP
RSP
Reset Stack Pointer
Operation
SPL ← $FF; SPH is unchanged
Description
For M68HC08 compatibility, the HCS08 RSP instruction only sets the least significant byte of SP to
$FF. The most significant byte is unaffected.
In most M68HC05 MCUs, RAM only goes to $00FF. In most HCS08s, however, RAM extends beyond
$00FF. Therefore, do not locate the stack in direct address space which is more valuable for
commonly accessed variables. In new HCS08 programs, it is more appropriate to initialize the stack
pointer to the address of the last location (highest address) in the on-chip RAM, shortly after reset.
This code segment demonstrates a typical method for initializing SP.
LDHX
TXS
#RamLast+1
; Point at next addr past RAM
; SP <-(H:X)-1
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
RSP
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
9C
HCS08
Cycles
Access
Detail
1
p
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Instruction Set
RTI
RTI
Return from Interrupt
Operation
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)
Restore CCR from stack
Restore A from stack
Restore X from stack
Restore PCH from stack
Restore PCL from stack
Description
The condition codes, the accumulator, X (index register low), and the program counter are restored
to the state previously saved on the stack. The I bit will be cleared if the corresponding bit stored on
the stack is 0, the normal case. If this instruction causes the I bit to change from 1 to 0, a one bus
cycle delay is imposed before interrupts are allowed. This ensures that the next instruction after an
RTI instruction will always be executed, even if an interrupt was pending before the RTI instruction
was executed and bit 3 of the CCR value on the stack cleared.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
Set or cleared according to the byte pulled from the stack into CCR.
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
RTI
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
80
HCS08
Cycles
Access
Detail
9
uuuuufppp
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275
Instruction Set Details
RTS
RTS
Return from Subroutine
Operation
SP ← SP + $0001; pull (PCH)
SP ← SP + $0001; pull (PCL)
Restore PCH from stack
Restore PCL from stack
Description
The stack pointer is incremented by 1. The contents of the byte of memory that is pointed to by the
stack pointer are loaded into the high-order byte of the program counter. The stack pointer is again
incremented by 1. The contents of the byte of memory that are pointed to by the stack pointer are
loaded into the low-order eight bits of the program counter. Program execution resumes at the
address that was just restored from the stack.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
RTS
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
81
HCS08
Cycles
Access
Detail
6
uufppp
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Freescale Semiconductor
Instruction Set
SBC
SBC
Subtract with Carry
Operation
A ← (A) – (M) – (C)
Description
Subtracts the contents of M and the contents of the C bit of the CCR from the contents of A and places
the result in A. This is useful for multi-precision subtract algorithms involving operands with more than
eight bits.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: A7&M7&R7 | A7&M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise. Literally read,
an overflow condition occurs if a positive number is subtracted from a negative number with a
positive result, or, if a negative number is subtracted from a positive number with a negative
result.
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: A7&M7 | M7&R7 | R7&A7
Set if the unsigned value of the contents of memory plus the previous carry are larger than the
unsigned value of the accumulator; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
HCS08
Cycles
Access
Detail
SBC
#opr8i
IMM
A2
ii
2
pp
SBC
opr8a
DIR
B2
dd
3
rpp
SBC
opr16a
EXT
C2
hh
ll
4
prpp
SBC
SBC
oprx16,X
IX2
D2
ee
ff
4
prpp
oprx8,X
IX1
E2
ff
3
rpp
SBC
,X
IX
F2
3
rfp
SBC
oprx16,SP
SP2
9ED2
ee
5
pprpp
SBC
oprx8,SP
SP1
9EE2
ff
4
prpp
Opcode
Operand(s)
ff
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277
Instruction Set Details
SEC
SEC
Set Carry Bit
Operation
C bit ← 1
Description
Sets the C bit in the condition code register (CCR). SEC may be used to set up the C bit prior to a shift
or rotate instruction that involves the C bit.
Condition Codes and Boolean Formulae
V
—
1
1
H
I
N
Z
C
—
—
—
—
1
C: 1
Set
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
SEC
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
99
HCS08
Cycles
Access
Detail
1
p
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Freescale Semiconductor
Instruction Set
SEI
SEI
Set Interrupt Mask Bit
Operation
I bit ← 1
Description
Sets the interrupt mask bit in the condition code register (CCR). The microprocessor is inhibited from
responding to interrupts while the I bit is set. The I bit actually changes at the end of the cycle where
SEI executed. This is too late to stop an interrupt that arrived during execution of the SEI instruction
so it is possible that an interrupt request could be serviced after the SEI instruction before the next
instruction after SEI is executed. The global I-bit interrupt mask takes effect before the next instruction
can be completed.
Condition Codes and Boolean Formulae
V
—
I:
1
1
H
I
N
Z
C
—
1
—
—
—
1
Set
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
SEI
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
9B
HCS08
Cycles
Access
Detail
1
p
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
279
Instruction Set Details
STA
STA
Store Accumulator in Memory
Operation
M ← (A)
Description
Stores the contents of A in memory. The contents of A remain unchanged. The N condition code is
set if the most significant bit of A is set, the Z bit is set if A was $00, and V is cleared. This allows
conditional branching after the store without having to do a separate test or compare.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: A7
Set if MSB of result is 1; cleared otherwise
Z: A7&A6&A5&A4&A3&A2&A1&A0
Set if result is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
STA
opr8a
DIR
STA
opr16a
EXT
C7
hh
ll
4
pwpp
STA
oprx16,X
IX2
D7
ee
ff
4
pwpp
STA
oprx8,X
IX1
E7
ff
3
wpp
STA
,X
IX
F7
2
wp
5
ppwpp
4
pwpp
Opcode
B7
Operand(s)
dd
STA
oprx16,SP
SP2
9ED7
ee
STA
oprx8,SP
SP1
9EE7
ff
ff
HCS08
Cycles
Access
Detail
3
wpp
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280
Freescale Semiconductor
Instruction Set
STHX
STHX
Store Index Register
Operation
(M:M + $0001) ← (H:X)
Description
Stores the contents of H in memory location M and then the contents of X into the next memory
location (M + $0001). The N condition code bit is set if the most significant bit of H was set, the Z bit
is set if the value of H:X was $0000, and V is cleared. This allows conditional branching after the store
without having to do a separate test or compare.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: R15
Set if MSB of result is 1; cleared otherwise
Z: R15&R14&R13&R12&R11&R10&R9&R8
&R7&R6&R5&R4&R3&R2&R1&R0
Set if the result is $0000; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
STHX
opr8a
DIR
35
dd
STHX
opr16a
EXT
96
hh
STHX
oprx8,SP
SP1
9E FF
Opcode
Operand(s)
ll
ff
HCS08
Cycles
Access
Detail
4
wwpp
5
pwwpp
5
pwwpp
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281
Instruction Set Details
STOP
STOP
Enable IRQ Pin, Stop Processing
Operation
I bit ← 0; stop processing
Description
Reduces power consumption by eliminating all dynamic power dissipation. Depending on system
configuration, this instruction is used to enter stop1, stop2, or stop3 mode. (See module
documentation for the behavior of these modes and module reactions to the stop instruction.)
The external interrupt pin is enabled and the I bit in the condition code register (CCR) is cleared to
enable interrupts. Interrupts can be used to exit stop3 only.
Finally, the oscillator is inhibited to put the MCU into the stop condition. In stop1 or stop2 mode, when
either the RESET pin or IRQ pin goes low, the reset vector is fetched and the MCU operates as if a
POR has occurred. For stop3 mode, if an IRQ, KBI, or RTI interrupt occurs, the associated service
routine is executed. Upon stop recovery, normally the MCU defaults to a self-clocked system clock
source so there is little or no startup delay.
Some HCS08 derivatives can be configured so the oscillator and real-time interrupt (RTI) module
continue to run in stop mode so no external components are needed to make the MCU periodically
wake up from stop. Also, if the background debug system is enabled (ENBDM), only stop3 mode is
entered and the oscillator continues to run so a host debug system can still force the target MCU into
active background mode.
Condition Codes and Boolean Formulae
V
—
I:
1
1
H
I
N
Z
C
—
0
—
—
—
0
Cleared
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
STOP
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
8E
HCS08
Cycles
Access
Detail
2+stop
fp
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Freescale Semiconductor
Instruction Set
STX
STX
Store X (Index Register Low) in Memory
Operation
M ← (X)
Description
Stores the contents of X in memory. The contents of X remain unchanged. The N condition code is
set if the most significant bit of X was set, the Z bit is set if X was $00, and V is cleared. This allows
conditional branching after the store without having to do a separate test or compare.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: X7
Set if MSB of result is 1; cleared otherwise
Z: X7&X6&X5&X4&X3&X2&X1&X0
Set if X is $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
Machine Code
STX
opr8a
DIR
STX
opr16a
EXT
CF
hh
ll
4
pwpp
STX
oprx16,X
IX2
DF
ee
ff
4
pwpp
STX
oprx8,X
IX1
EF
ff
3
wpp
STX
,X
IX
FF
2
wp
5
ppwpp
4
pwpp
Opcode
BF
Operand(s)
dd
STX
oprx16,SP
SP2
9EDF
ee
STX
oprx8,SP
SP1
9EEF
ff
ff
HCS08
Cycles
Access
Detail
3
wpp
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283
Instruction Set Details
SUB
SUB
Subtract
Operation
A ← (A) – (M)
Description
Subtracts the contents of M from A and places the result in A
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
—
—
V: A7&M7&R7 | A7&M7&R7
Set if a two’s complement overflow resulted from the operation; cleared otherwise. Literally read,
an overflow condition occurs if a positive number is subtracted from a negative number with a
positive result, or, if a negative number is subtracted from a positive number with a negative
result.
N: R7
Set if MSB of result is 1; cleared otherwise
Z: R7&R6&R5&R4&R3&R2&R1&R0
Set if result is $00; cleared otherwise
C: A7&M7 | M7&R7 | R7&A7
Set if the unsigned value of the contents of memory is larger than the unsigned value of the
accumulator; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
Source
Form
Addr.
Mode
SUB
#opr8i
IMM
SUB
opr8a
DIR
B0
dd
3
rpp
SUB
opr16a
EXT
C0
hh
ll
4
prpp
SUB
oprx16,X
IX2
D0
ee
ff
4
prpp
SUB
oprx8,X
IX1
E0
ff
3
rpp
IX
Machine Code
Opcode
A0
Operand(s)
ii
SUB
X
SUB
oprx16,SP
SP2
9ED0
F0
ee
SUB
oprx8,SP
SP1
9EE0
ff
ff
HCS08
Cycles
Access
Detail
2
pp
3
rfp
5
pprpp
4
prpp
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Instruction Set
SWI
SWI
Software Interrupt
Operation
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) – $0001
Push bit ← 1
PCH ← ($FFFC)
PCL ← ($FFFD)
Increment PC to return address
Push low half of return address
Push high half of return address
Push index register on stack
Push A on stack
Push CCR on stack
Mask further interrupts
Vector fetch (high byte)
Vector fetch (low byte)
Description
The program counter (PC) is incremented by 1 to point at the instruction after the SWI. The PC, index
register, and accumulator are pushed onto the stack. The condition code register (CCR) bits are then
pushed onto the stack, with bits V, H, I, N, Z, and C going into bit positions 7 and 4–0. Bit positions 6
and 5 contain 1s. The stack pointer is decremented by 1 after each byte of data is stored on the stack.
The interrupt mask bit is then set. The program counter is then loaded with the address stored in the
SWI vector located at memory locations $FFFC and $FFFD. This instruction is not maskable by the
I bit.
Condition Codes and Boolean Formulae
V
—
I:
1
1
H
I
N
Z
C
—
1
—
—
—
1
Set
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
SWI
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
83
HCS08
Cycles
Access
Detail
11
sssssvvfppp
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285
Instruction Set Details
TAP
TAP
Transfer Accumulator to Processor Status Byte
Operation
CCR ← (A)
bit 7
6
5
4
3
2
1
bit 0
A
V
1
1
H
I
N
Z
C
CCR
Carry/Borrow
Zero
Negative
I Interrupt
Mask
Half Carry
Overflow
(Two’s
Complement)
Description
Transfers the contents of A to the condition code register (CCR). The contents of A are unchanged.
If this instruction causes the I bit to change from 1 to 0, a one bus cycle delay is imposed before
interrupts are allowed. This ensures that the next instruction after a TAP instruction will always be
executed even if an interrupt was pending before the TAP instruction was executed with bit 3 of
accumulator A cleared.
Condition Codes and Boolean Formulae
V
1
1
H
I
N
Z
C
Set or cleared according to the value that was in the accumulator.
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
TAP
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
84
HCS08
Cycles
Access
Details
1
p
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Freescale Semiconductor
Instruction Set
TAX
TAX
Transfer Accumulator to X (Index Register Low)
Operation
X ← (A)
Description
Loads X with the contents of the accumulator (A). The contents of A are unchanged.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
TAX
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
97
HCS08
Cycles
Access
Detail
1
p
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287
Instruction Set Details
TPA
TPA
Transfer Processor Status Byte to Accumulator
Operation
A ← (CCR)
bit 7
6
5
4
3
2
1
bit 0
A
V
1
1
H
I
N
Z
C
CCR
Carry/Borrow
Zero
Negative
I Interrupt
Mask
Half Carry
Overflow
(Two’s
Complement)
Description
Transfers the contents of the condition code register (CCR) into the accumulator (A)
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
TPA
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
85
HCS08
Cycles
Access
Detail
1
p
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Freescale Semiconductor
Instruction Set
TST
TST
Test for Negative or Zero
Operation
(A) – $00
Or (X) – $00
Or (M) – $00
Description
Sets the N and Z condition codes according to the contents of A, X, or M. The contents of A, X, and
M are not altered.
Condition Codes and Boolean Formulae
V
0
1
1
H
I
N
Z
C
—
—
—
V: 0
Cleared
N: M7
Set if MSB of the tested value is 1; cleared otherwise
Z: M7&M6&M5&M4&M3&M2&M1&M0
Set if A, X, or M contains $00; cleared otherwise
Source Forms, Addressing Modes, Machine Code, Cycles, and Access Details
TST
Source
Form
Addr.
Mode
opr8a
DIR
3D
INH (A)
4D
TSTA
TSTX
Machine Code
Opcode
INH (X)
5D
TST
oprx8,X
IX1
6D
TST
,X
IX
7D
TST
oprx8,SP
SP1
9E6D
Operand(s)
dd
ff
ff
HCS08
Cycles
Access
Detail
4
rfpp
1
p
1
p
4
rfpp
3
rfp
5
prfpp
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289
Instruction Set Details
TSX
TSX
Transfer Stack Pointer to Index Register
Operation
H:X ← (SP) + $0001
Description
Loads index register (H:X) with 1 plus the contents of the stack pointer (SP). The contents of SP
remain unchanged. After a TSX instruction, H:X points to the last value that was stored on the stack.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
TSX
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
95
HCS08
Cycles
Access
Details
2
fp
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Freescale Semiconductor
Instruction Set
TXA
TXA
Transfer X (Index Register Low) to Accumulator
Operation
A ← (X)
Description
Loads the accumulator (A) with the contents of X. The contents of X are not altered.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
TXA
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
9F
HCS08
Cycles
Access
Details
1
p
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291
Instruction Set Details
TXS
TXS
Transfer Index Register to Stack Pointer
Operation
SP ← (H:X) – $0001
Description
Loads the stack pointer (SP) with the contents of the index register (H:X) minus 1. The contents of
H:X are not altered.
Condition Codes and Boolean Formulae
None affected
V
—
1
1
H
I
N
Z
C
—
—
—
—
—
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
TXS
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
94
HCS08
Cycles
Access
Details
2
fp
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Instruction Set
WAIT
WAIT
Enable Interrupts; Stop Processor
Operation
I bit ← 0; inhibit CPU clocking until interrupted
Description
Reduces power consumption by eliminating dynamic power dissipation in some portions of the MCU.
The timer, the timer prescaler, and the on-chip peripherals continue to operate (if enabled) because
they are potential sources of an interrupt. Wait causes enabling of interrupts by clearing the I bit in the
CCR and stops clocking of processor circuits.
Interrupts from on-chip peripherals may be enabled or disabled by local control bits prior to execution
of the WAIT instruction.
When either the RESET or IRQ pin goes low or when any on-chip system requests interrupt service,
the processor clocks are enabled, and the reset, IRQ, or other interrupt service request is processed.
Condition Codes and Boolean Formulae
V
—
I:
1
1
H
I
N
Z
C
—
0
—
—
—
0
Cleared
Source Form, Addressing Mode, Machine Code, Cycles, and Access Detail
Source
Form
WAIT
Addr.
Mode
INH
Machine Code
Opcode
Operand(s)
8F
HCS08
Cycles
Access
Details
2+wait
fp
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Instruction Set Details
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Appendix B
Equate File Conventions
B.1 Introduction
This appendix describes the conventions used to create and use device definition files, usually called
equate files. The equate file for the first device derivative in the HCS08 Family (9S08GB60_v1.equ) is
used as an example and the entire equate file is included in B.5 Complete Equate File for MC9S08GB60.
Each new member of the HCS08 Family will have a similar equate file available on the Freescale MCU
Web site http://freescale.com
Equate files do not produce object code, so including this file in an application program does not affect
program size. The equate file defines all control register and bit names from the manufacturer’s
documentation into a form that is understood by the assembler. The equate file also defines some basic
system attributes including the beginning and ending addresses of on-chip memory blocks and the name
and location of all interrupt vectors. The file is comprised entirely of EQU directives and comments.
All register names and bit names use uppercase characters so they match the spelling and capitalization
used in the data sheet and other manuals. To help prevent conflicting register names as new device
derivatives are introduced, register names will start with a 2- or 3-character prefix that identifies the
module they are located in. For example, the KBI in KBISC indicates this register is located in the
keyboard interrupt module (KBI). When more than one copy of a module is included in the MCU
derivative, a digit immediately after this prefix indicates which instance of the module the register is
located in, such as SCI1C1 and SCI2C1, which refer to the control register number 1 in SCI module 1
and 2, respectively.
Occasionally, two different control bits may have the same name. The most common case occurs when
two identical modules are included on the same MCU. In this situation, the matching bit names don’t really
conflict because the definitions equate the bit name to its bit number and its bit position which are the
same for both registers. When two identical modules are included, the register names must include the
module number in the name to make each register name unique, but the bit numbers and bit positions
can simply be defined once. These definitions are valid regardless of which register is being referenced,
so there is no conflict.
In this example, the first two lines identify the status register number 2 for each of the SCI modules. The
remaining lines define the bit position and bit number once and these definitions may be used with either
register.
SCI1S2:
equ
$1D
;SCI1 status register 2
SCI2S2:
equ
$25
;SCI2 status register 2
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
RAF:
equ
0
;(bit #0) Rx active flag
; bit position masks
mRAF:
equ
%00000001
;receiver active flag
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295
Equate File Conventions
As future modules are designed for the HCS08 Family, care will be taken to avoid bit names that are the
same in different registers but are not located in the same bit position in all registers where the name
appears.
B.2 Memory Map Definition
The first set of EQU directives defines the starting and ending addresses for each on-chip memory block.
The main program memory is called “Rom” even if it is actually FLASH memory in the HCS08 Family. For
each memory, there is an xxxStart definition and an xxxLast definition. This book uses a combination of
uppercase and lowercase letters to break up multiword labels so “RomStart” is the convention rather than
“rom_start.”
RomStart:
HighRegs:
Rom1Start:
RomLast:
RamStart:
RamLast:
equ
equ
equ
equ
equ
equ
$1080
$1800
$182C
$FFFF
$0080
$107F
;start of 60K flash
;start of high page registers
;start of flash after high regs
;last flash location
;start of 4096 byte RAM
;last RAM location
B.3 Vector Definitions
The next set of EQU directives defines the location of each interrupt vector starting from the lowest vector
address and continuing through the reset vector location at the end of memory ($FFFE:FFFF). The names
for each of these vector definitions starts with an uppercase V. Care should be taken to use the same
name for these vectors in equate files for other derivatives that reuse a module such as the TPM or SCI.
Vrti:
Viic:
Vatd:
Vkeyboard:
Vsci2tx:
Vsci2rx:
Vsci2err:
Vsci1tx:
Vsci1rx:
Vsci1err:
Vspi:
Vtpm2ovf:
Vtpm2ch4:
Vtpm2ch3:
Vtpm2ch2:
Vtpm2ch1:
Vtpm2ch0:
Vtpm1ovf:
Vtpm1ch2:
Vtpm1ch1:
Vtpm1ch0:
Vicg:
Vlvd:
Virq:
Vswi:
Vreset:
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
equ
$FFCC
$FFCE
$FFD0
$FFD2
$FFD4
$FFD6
$FFD8
$FFDA
$FFDC
$FFDE
$FFE0
$FFE2
$FFE4
$FFE6
$FFE8
$FFEA
$FFEC
$FFEE
$FFF0
$FFF2
$FFF4
$FFF6
$FFF8
$FFFA
$FFFC
$FFFE
;RTI (periodic interrupt) vector
;IIC vector
;analog to digital conversion vector
;keyboard vector
;SCI2 transmit vector
;SCI2 receive vector
;SCI2 error vector
;SCI1 transmit vector
;SCI1 receive vector
;SCI1 error vector
;SPI vector
;TPM2 overflow vector
;TPM2 channel 4 vector
;TPM2 channel 3 vector
;TPM2 channel 2 vector
;TPM2 channel 1 vector
;TPM2 channel 0 vector
;TPM1 overflow vector
;TPM1 channel 2 vector
;TPM1 channel 1 vector
;TPM1 channel 0 vector
;ICG vector
;low voltage detect vector
;IRQ pin vector
;SWI vector
;reset vector
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Bits Defined in Two Ways
B.4 Bits Defined in Two Ways
Bit names in the equate files for HCS08 MCUs need to be defined in two separate ways:
• With their bit number (0–7)
• A bit-position mask which is used in instructions such as AND, ORA, BIT, etc.
In the equate file, the bit name is first equated to its bit number (0–7), and then its bit position mask is
equated to the bit name with a prefix of lowercase m, as in the next example.
SCI1S1:
equ
$1C
;SCI1 status register 1
SCI2S1:
equ
$24
;SCI2 status register 1
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
TDRE:
equ
7
;(bit #7) Tx data register empty
TC:
equ
6
;(bit #6) transmit complete
RDRF:
equ
5
;(bit #5) Rx data register full
IDLE:
equ
4
;(bit #4) idle line detected
OR:
equ
3
;(bit #3) Rx over run
NF:
equ
2
;(bit #2) Rx noise flag
FE:
equ
1
;(bit #1) Rx framing error
PF:
equ
0
;(bit #0) Rx parity failed
; bit position masks
mTDRE:
equ
%10000000
;transmit data register empty
mTC:
equ
%01000000
;transmit complete
mRDRF:
equ
%00100000
;receive data register full
mIDLE:
equ
%00010000
;idle line detected
mOR:
equ
%00001000
;receiver over run
mNF:
equ
%00000100
;receiver noise flag
mFE:
equ
%00000010
;receiver framing error
mPF:
equ
%00000001
;received parity failed
The next example shows the bit number variation of a bit definition. The operand field of the BRCLR
instruction includes three items separated by commas. RDRF is converted to the number 5 which tells the
assembler to use the bit-5 variation of the BRCLR instruction (opcode = $0B). The next item, SCI1S1,
tells the assembler the operand to be tested is located at the direct addressing mode address $001C (just
1C in the object code). The last item, waitRDRF, tells the assembler to branch back to the same BRCLR
instruction if the RDRF status bit is found to be still clear (0).
450 120A 0B 1C FD
waitRDRF:
brclr
RDRF,SCI1S1,waitRDRF ;loop till RDRF set
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297
Equate File Conventions
The next example shows an expression combining the bit masks for the OR, NF, FE, and PF status bits.
In this example, the bit names are used with a preceding m to get the bit position mask rather than the bit
number. A simple addition operator (+) combines the bit masks. Although a logical OR might have been
more correct in this case, not all assemblers use the same character to indicate the logical OR operation
so the + is more portable among assemblers. The plus operator can be used in this case because the
individual bit masks do not have any overlapping logic 1 bits.
“
“
“ “
413
414 11F1 B6 1C
415 11F3 A5 0F
416 11F5 26 00
417
mOR:
equ
%00001000
;receiver over run
mNF:
equ
%00000100
;receiver noise flag
mFE:
equ
%00000010
;receiver framing error
mPF:
equ
%00000001
;received parity failed
“
“
“
“
; BIT example to check several error flags in SCI status reg
lda
SCI1S1
;read SCI status register
bit
#(mOR+mNF+mFE+mPF) ;mask of all error flags
bne
sciError
;branch if any flags set
; A still contains undisturbed status register
The 0F in the object code field of line 415 shows the assembler evaluated (mOR+mNF+mFE+mFF) to
$0F. The A5 in the object code field of the same line is the opcode for the immediate addressing mode
variation of the BIT instruction.
B.5 Complete Equate File for MC9S08GB60
The following listing is a complete equate file for the MC9S08GB60 MCU and is a complete example of
an equate file for an HCS08 MCU. Each derivative in the HCS08 Family has a similar equate file posted
on the Freescale Web site for free downloading.
;********************************************************************************************
;* Title: 9S08GB60_v1.EQU
(c) Freescale Inc. 2003 All rights reserved.
;********************************************************************************************
;* Author: Jim Sibigtroth - Freescale TSPG
;*
;* Description: Register and bit name definitions for 9S08GB60
;*
;* Documentation: 9S08GB60 family Data Sheet for register and bit explanations
;* HCS08 Family Reference Manual (HCS08RM1/D) appendix B for explanation of equate files
;*
;* Include Files: none
;*
;* Assembler: Metrowerks Code Warrior 3.0 (pre-release)
;*
or P&E Microcomputer Systems - CASMS08 (beta v4.02)
;*
;* Revision History: not yet released
;* Rev #
Date
Who
Comments
;* ----- ----------- ------ -------------------------------------------;* 1.2
24-Apr-03
J-Sib
correct minor typos in comments
;* 1.1
21-Apr-03
J-Sib
comments and modify for CW 3.0 project
;* 1.0
15-Apr-03
J-Sib
Release version for 9S09GB60
;********************************************************************************************
HCS08 Family Reference Manual, Rev. 2
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Complete Equate File for MC9S08GB60
;**** Memory Map and Interrupt Vectors ****************************************************
;*
RomStart:
equ
$1080
;start of 60K flash
HighRegs:
equ
$1800
;start of high page registers
Rom1Start:
equ
$182C
;start of flash after high regs
RomLast:
equ
$FFFF
;last flash location
RamStart:
equ
$0080
;start of 4096 byte RAM
RamLast:
equ
$107F
;last RAM location
;
Vrti:
equ
$FFCC
;RTI (periodic interrupt) vector
Viic:
equ
$FFCE
;IIC vector
Vatd:
equ
$FFD0
;analog to digital conversion vector
Vkeyboard:
equ
$FFD2
;keyboard vector
Vsci2tx:
equ
$FFD4
;SCI2 transmit vector
Vsci2rx:
equ
$FFD6
;SCI2 receive vector
Vsci2err:
equ
$FFD8
;SCI2 error vector
Vsci1tx:
equ
$FFDA
;SCI1 transmit vector
Vsci1rx:
equ
$FFDC
;SCI1 receive vector
Vsci1err:
equ
$FFDE
;SCI1 error vector
Vspi:
equ
$FFE0
;SPI vector
Vtpm2ovf:
equ
$FFE2
;TPM2 overflow vector
Vtpm2ch4:
equ
$FFE4
;TPM2 channel 4 vector
Vtpm2ch3:
equ
$FFE6
;TPM2 channel 3 vector
Vtpm2ch2:
equ
$FFE8
;TPM2 channel 2 vector
Vtpm2ch1:
equ
$FFEA
;TPM2 channel 1 vector
Vtpm2ch0:
equ
$FFEC
;TPM2 channel 0 vector
Vtpm1ovf:
equ
$FFEE
;TPM1 overflow vector
Vtpm1ch2:
equ
$FFF0
;TPM1 channel 2 vector
Vtpm1ch1:
equ
$FFF2
;TPM1 channel 1 vector
Vtpm1ch0:
equ
$FFF4
;TPM1 channel 0 vector
Vicg:
equ
$FFF6
;ICG vector
Vlvd:
equ
$FFF8
;low voltage detect vector
Virq:
equ
$FFFA
;IRQ pin vector
Vswi:
equ
$FFFC
;SWI vector
Vreset:
equ
$FFFE
;reset vector
;**** Input/Output (I/O) Ports ************************************************************
;*
PTAD:
equ
$00
;I/O port A data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTAD7:
equ
7
;bit #7
PTAD6:
equ
6
;bit #6
PTAD5:
equ
5
;bit #5
PTAD4:
equ
4
;bit #4
PTAD3:
equ
3
;bit #3
PTAD2:
equ
2
;bit #2
PTAD1:
equ
1
;bit #1
PTAD0:
equ
0
;bit #0
; bit position masks
mPTAD7:
equ
%10000000
;port A bit 7
mPTAD6:
equ
%01000000
;port A bit 6
mPTAD5:
equ
%00100000
;port A bit 5
mPTAD4:
equ
%00010000
;port A bit 4
mPTAD3:
equ
%00001000
;port A bit 3
mPTAD2:
equ
%00000100
;port A bit 2
mPTAD1:
equ
%00000010
;port A bit 1
mPTAD0:
equ
%00000001
;port A bit 0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
299
Equate File Conventions
PTAPE:
equ
$01
;I/O port A pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTAPE7:
equ
7
;bit #7
PTAPE6:
equ
6
;bit #6
PTAPE5:
equ
5
;bit #5
PTAPE4:
equ
4
;bit #4
PTAPE3:
equ
3
;bit #3
PTAPE2:
equ
2
;bit #2
PTAPE1:
equ
1
;bit #1
PTAPE0:
equ
0
;bit #0
; bit position masks
mPTAPE7:
equ
%10000000
;port A bit 7
mPTAPE6:
equ
%01000000
;port A bit 6
mPTAPE5:
equ
%00100000
;port A bit 5
mPTAPE4:
equ
%00010000
;port A bit 4
mPTAPE3:
equ
%00001000
;port A bit 3
mPTAPE2:
equ
%00000100
;port A bit 2
mPTAPE1:
equ
%00000010
;port A bit 1
mPTAPE0:
equ
%00000001
;port A bit 0
PTASE:
equ
$02
;I/O port A slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTASE7:
equ
7
;bit #7
PTASE6:
equ
6
;bit #6
PTASE5:
equ
5
;bit #5
PTASE4:
equ
4
;bit #4
PTASE3:
equ
3
;bit #3
PTASE2:
equ
2
;bit #2
PTASE1:
equ
1
;bit #1
PTASE0:
equ
0
;bit #0
; bit position masks
mPTASE7:
equ
%10000000
;port A bit 7
mPTASE6:
equ
%01000000
;port A bit 6
mPTASE5:
equ
%00100000
;port A bit 5
mPTASE4:
equ
%00010000
;port A bit 4
mPTASE3:
equ
%00001000
;port A bit 3
mPTASE2:
equ
%00000100
;port A bit 2
mPTASE1:
equ
%00000010
;port A bit 1
mPTASE0:
equ
%00000001
;port A bit 0
PTADD:
equ
$03
;I/O port A data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTADD7:
equ
7
;bit #7
PTADD6:
equ
6
;bit #6
PTADD5:
equ
5
;bit #5
PTADD4:
equ
4
;bit #4
PTADD3:
equ
3
;bit #3
PTADD2:
equ
2
;bit #2
PTADD1:
equ
1
;bit #1
PTADD0:
equ
0
;bit #0
; bit position masks
mPTADD7:
equ
%10000000
;port A bit 7
mPTADD6:
equ
%01000000
;port A bit 6
mPTADD5:
equ
%00100000
;port A bit 5
mPTADD4:
equ
%00010000
;port A bit 4
mPTADD3:
equ
%00001000
;port A bit 3
mPTADD2:
equ
%00000100
;port A bit 2
mPTADD1:
equ
%00000010
;port A bit 1
mPTADD0:
equ
%00000001
;port A bit 0
HCS08 Family Reference Manual, Rev. 2
300
Freescale Semiconductor
Complete Equate File for MC9S08GB60
PTBD:
equ
$04
;I/O port B data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTBD7:
equ
7
;bit #7
PTBD6:
equ
6
;bit #6
PTBD5:
equ
5
;bit #5
PTBD4:
equ
4
;bit #4
PTBD3:
equ
3
;bit #3
PTBD2:
equ
2
;bit #2
PTBD1:
equ
1
;bit #1
PTBD0:
equ
0
;bit #0
; bit position masks
mPTBD7:
equ
%10000000
;port B bit 7
mPTBD6:
equ
%01000000
;port B bit 6
mPTBD5:
equ
%00100000
;port B bit 5
mPTBD4:
equ
%00010000
;port B bit 4
mPTBD3:
equ
%00001000
;port B bit 3
mPTBD2:
equ
%00000100
;port B bit 2
mPTBD1:
equ
%00000010
;port B bit 1
mPTBD0:
equ
%00000001
;port B bit 0
PTBPE:
equ
$05
;I/O port B pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTBPE7:
equ
7
;bit #7
PTBPE6:
equ
6
;bit #6
PTBPE5:
equ
5
;bit #5
PTBPE4:
equ
4
;bit #4
PTBPE3:
equ
3
;bit #3
PTBPE2:
equ
2
;bit #2
PTBPE1:
equ
1
;bit #1
PTBPE0:
equ
0
;bit #0
; bit position masks
mPTBPE7:
equ
%10000000
;port B bit 7
mPTBPE6:
equ
%01000000
;port B bit 6
mPTBPE5:
equ
%00100000
;port B bit 5
mPTBPE4:
equ
%00010000
;port B bit 4
mPTBPE3:
equ
%00001000
;port B bit 3
mPTBPE2:
equ
%00000100
;port B bit 2
mPTBPE1:
equ
%00000010
;port B bit 1
mPTBPE0:
equ
%00000001
;port B bit 0
PTBSE:
equ
$06
;I/O port B slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTBSE7:
equ
7
;bit #7
PTBSE6:
equ
6
;bit #6
PTBSE5:
equ
5
;bit #5
PTBSE4:
equ
4
;bit #4
PTBSE3:
equ
3
;bit #3
PTBSE2:
equ
2
;bit #2
PTBSE1:
equ
1
;bit #1
PTBSE0:
equ
0
;bit #0
; bit position masks
mPTBSE7:
equ
%10000000
;port B bit 7
mPTBSE6:
equ
%01000000
;port B bit 6
mPTBSE5:
equ
%00100000
;port B bit 5
mPTBSE4:
equ
%00010000
;port B bit 4
mPTBSE3:
equ
%00001000
;port B bit 3
mPTBSE2:
equ
%00000100
;port B bit 2
mPTBSE1:
equ
%00000010
;port B bit 1
mPTBSE0:
equ
%00000001
;port B bit 0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
301
Equate File Conventions
PTBDD:
equ
$07
;I/O port B data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTBDD7:
equ
7
;bit #7
PTBDD6:
equ
6
;bit #6
PTBDD5:
equ
5
;bit #5
PTBDD4:
equ
4
;bit #4
PTBDD3:
equ
3
;bit #3
PTBDD2:
equ
2
;bit #2
PTBDD1:
equ
1
;bit #1
PTBDD0:
equ
0
;bit #0
; bit position masks
mPTBDD7:
equ
%10000000
;port B bit 7
mPTBDD6:
equ
%01000000
;port B bit 6
mPTBDD5:
equ
%00100000
;port B bit 5
mPTBDD4:
equ
%00010000
;port B bit 4
mPTBDD3:
equ
%00001000
;port B bit 3
mPTBDD2:
equ
%00000100
;port B bit 2
mPTBDD1:
equ
%00000010
;port B bit 1
mPTBDD0:
equ
%00000001
;port B bit 0
PTCD:
equ
$08
;I/O port C data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTCD7:
equ
7
;bit #7
PTCD6:
equ
6
;bit #6
PTCD5:
equ
5
;bit #5
PTCD4:
equ
4
;bit #4
PTCD3:
equ
3
;bit #3
PTCD2:
equ
2
;bit #2
PTCD1:
equ
1
;bit #1
PTCD0:
equ
0
;bit #0
; bit position masks
mPTCD7:
equ
%10000000
;port C bit 7
mPTCD6:
equ
%01000000
;port C bit 6
mPTCD5:
equ
%00100000
;port C bit 5
mPTCD4:
equ
%00010000
;port C bit 4
mPTCD3:
equ
%00001000
;port C bit 3
mPTCD2:
equ
%00000100
;port C bit 2
mPTCD1:
equ
%00000010
;port C bit 1
mPTCD0:
equ
%00000001
;port C bit 0
PTCPE:
equ
$09
;I/O port C pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTCPE7:
equ
7
;bit #7
PTCPE6:
equ
6
;bit #6
PTCPE5:
equ
5
;bit #5
PTCPE4:
equ
4
;bit #4
PTCPE3:
equ
3
;bit #3
PTCPE2:
equ
2
;bit #2
PTCPE1:
equ
1
;bit #1
PTCPE0:
equ
0
;bit #0
; bit position masks
mPTCPE7:
equ
%10000000
;port C bit 7
mPTCPE6:
equ
%01000000
;port C bit 6
mPTCPE5:
equ
%00100000
;port C bit 5
mPTCPE4:
equ
%00010000
;port C bit 4
mPTCPE3:
equ
%00001000
;port C bit 3
mPTCPE2:
equ
%00000100
;port C bit 2
mPTCPE1:
equ
%00000010
;port C bit 1
mPTCPE0:
equ
%00000001
;port C bit 0
HCS08 Family Reference Manual, Rev. 2
302
Freescale Semiconductor
Complete Equate File for MC9S08GB60
PTCSE:
equ
$0A
;I/O port C slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTCSE7:
equ
7
;bit #7
PTCSE6:
equ
6
;bit #6
PTCSE5:
equ
5
;bit #5
PTCSE4:
equ
4
;bit #4
PTCSE3:
equ
3
;bit #3
PTCSE2:
equ
2
;bit #2
PTCSE1:
equ
1
;bit #1
PTCSE0:
equ
0
;bit #0
; bit position masks
mPTCSE7:
equ
%10000000
;port C bit 7
mPTCSE6:
equ
%01000000
;port C bit 6
mPTCSE5:
equ
%00100000
;port C bit 5
mPTCSE4:
equ
%00010000
;port C bit 4
mPTCSE3:
equ
%00001000
;port C bit 3
mPTCSE2:
equ
%00000100
;port C bit 2
mPTCSE1:
equ
%00000010
;port C bit 1
mPTCSE0:
equ
%00000001
;port C bit 0
PTCDD:
equ
$0B
;I/O port C data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTCDD7:
equ
7
;bit #7
PTCDD6:
equ
6
;bit #6
PTCDD5:
equ
5
;bit #5
PTCDD4:
equ
4
;bit #4
PTCDD3:
equ
3
;bit #3
PTCDD2:
equ
2
;bit #2
PTCDD1:
equ
1
;bit #1
PTCDD0:
equ
0
;bit #0
; bit position masks
mPTCDD7:
equ
%10000000
;port C bit 7
mPTCDD6:
equ
%01000000
;port C bit 6
mPTCDD5:
equ
%00100000
;port C bit 5
mPTCDD4:
equ
%00010000
;port C bit 4
mPTCDD3:
equ
%00001000
;port C bit 3
mPTCDD2:
equ
%00000100
;port C bit 2
mPTCDD1:
equ
%00000010
;port C bit 1
mPTCDD0:
equ
%00000001
;port C bit 0
PTDD:
equ
$0C
;I/O port D data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTDD7:
equ
7
;bit #7
PTDD6:
equ
6
;bit #6
PTDD5:
equ
5
;bit #5
PTDD4:
equ
4
;bit #4
PTDD3:
equ
3
;bit #3
PTDD2:
equ
2
;bit #2
PTDD1:
equ
1
;bit #1
PTDD0:
equ
0
;bit #0
; bit position masks
mPTDD7:
equ
%10000000
;port D bit 7
mPTDD6:
equ
%01000000
;port D bit 6
mPTDD5:
equ
%00100000
;port D bit 5
mPTDD4:
equ
%00010000
;port D bit 4
mPTDD3:
equ
%00001000
;port D bit 3
mPTDD2:
equ
%00000100
;port D bit 2
mPTDD1:
equ
%00000010
;port D bit 1
mPTDD0:
equ
%00000001
;port D bit 0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
303
Equate File Conventions
PTDPE:
equ
$0D
;I/O port D pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTDPE7:
equ
7
;bit #7
PTDPE6:
equ
6
;bit #6
PTDPE5:
equ
5
;bit #5
PTDPE4:
equ
4
;bit #4
PTDPE3:
equ
3
;bit #3
PTDPE2:
equ
2
;bit #2
PTDPE1:
equ
1
;bit #1
PTDPE0:
equ
0
;bit #0
; bit position masks
mPTDPE7:
equ
%10000000
;port D bit 7
mPTDPE6:
equ
%01000000
;port D bit 6
mPTDPE5:
equ
%00100000
;port D bit 5
mPTDPE4:
equ
%00010000
;port D bit 4
mPTDPE3:
equ
%00001000
;port D bit 3
mPTDPE2:
equ
%00000100
;port D bit 2
mPTDPE1:
equ
%00000010
;port D bit 1
mPTDPE0:
equ
%00000001
;port D bit 0
PTDSE:
equ
$0E
;I/O port D slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTDSE7:
equ
7
;bit #7
PTDSE6:
equ
6
;bit #6
PTDSE5:
equ
5
;bit #5
PTDSE4:
equ
4
;bit #4
PTDSE3:
equ
3
;bit #3
PTDSE2:
equ
2
;bit #2
PTDSE1:
equ
1
;bit #1
PTDSE0:
equ
0
;bit #0
; bit position masks
mPTDSE7:
equ
%10000000
;port D bit 7
mPTDSE6:
equ
%01000000
;port D bit 6
mPTDSE5:
equ
%00100000
;port D bit 5
mPTDSE4:
equ
%00010000
;port D bit 4
mPTDSE3:
equ
%00001000
;port D bit 3
mPTDSE2:
equ
%00000100
;port D bit 2
mPTDSE1:
equ
%00000010
;port D bit 1
mPTDSE0:
equ
%00000001
;port D bit 0
PTDDD:
equ
$0F
;I/O port D data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTDDD7:
equ
7
;bit #7
PTDDD6:
equ
6
;bit #6
PTDDD5:
equ
5
;bit #5
PTDDD4:
equ
4
;bit #4
PTDDD3:
equ
3
;bit #3
PTDDD2:
equ
2
;bit #2
PTDDD1:
equ
1
;bit #1
PTDDD0:
equ
0
;bit #0
; bit position masks
mPTDDD7:
equ
%10000000
;port D bit 7
mPTDDD6:
equ
%01000000
;port D bit 6
mPTDDD5:
equ
%00100000
;port D bit 5
mPTDDD4:
equ
%00010000
;port D bit 4
mPTDDD3:
equ
%00001000
;port D bit 3
mPTDDD2:
equ
%00000100
;port D bit 2
mPTDDD1:
equ
%00000010
;port D bit 1
mPTDDD0:
equ
%00000001
;port D bit 0
HCS08 Family Reference Manual, Rev. 2
304
Freescale Semiconductor
Complete Equate File for MC9S08GB60
PTED:
equ
$10
;I/O port E data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTED7:
equ
7
;bit #7
PTED6:
equ
6
;bit #6
PTED5:
equ
5
;bit #5
PTED4:
equ
4
;bit #4
PTED3:
equ
3
;bit #3
PTED2:
equ
2
;bit #2
PTED1:
equ
1
;bit #1
PTED0:
equ
0
;bit #0
; bit position masks
mPTED7:
equ
%10000000
;port E bit 7
mPTED6:
equ
%01000000
;port E bit 6
mPTED5:
equ
%00100000
;port E bit 5
mPTED4:
equ
%00010000
;port E bit 4
mPTED3:
equ
%00001000
;port E bit 3
mPTED2:
equ
%00000100
;port E bit 2
mPTED1:
equ
%00000010
;port E bit 1
mPTED0:
equ
%00000001
;port E bit 0
PTEPE:
equ
$11
;I/O port E pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTEPE7:
equ
7
;bit #7
PTEPE6:
equ
6
;bit #6
PTEPE5:
equ
5
;bit #5
PTEPE4:
equ
4
;bit #4
PTEPE3:
equ
3
;bit #3
PTEPE2:
equ
2
;bit #2
PTEPE1:
equ
1
;bit #1
PTEPE0:
equ
0
;bit #0
; bit position masks
mPTEPE7:
equ
%10000000
;port E bit 7
mPTEPE6:
equ
%01000000
;port E bit 6
mPTEPE5:
equ
%00100000
;port E bit 5
mPTEPE4:
equ
%00010000
;port E bit 4
mPTEPE3:
equ
%00001000
;port E bit 3
mPTEPE2:
equ
%00000100
;port E bit 2
mPTEPE1:
equ
%00000010
;port E bit 1
mPTEPE0:
equ
%00000001
;port E bit 0
PTESE:
equ
$12
;I/O port E slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTESE7:
equ
7
;bit #7
PTESE6:
equ
6
;bit #6
PTESE5:
equ
5
;bit #5
PTESE4:
equ
4
;bit #4
PTESE3:
equ
3
;bit #3
PTESE2:
equ
2
;bit #2
PTESE1:
equ
1
;bit #1
PTESE0:
equ
0
;bit #0
; bit position masks
mPTESE7:
equ
%10000000
;port E bit 7
mPTESE6:
equ
%01000000
;port E bit 6
mPTESE5:
equ
%00100000
;port E bit 5
mPTESE4:
equ
%00010000
;port E bit 4
mPTESE3:
equ
%00001000
;port E bit 3
mPTESE2:
equ
%00000100
;port E bit 2
mPTESE1:
equ
%00000010
;port E bit 1
mPTESE0:
equ
%00000001
;port E bit 0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
305
Equate File Conventions
PTEDD:
equ
$13
;I/O port E data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTEDD7:
equ
7
;bit #7
PTEDD6:
equ
6
;bit #6
PTEDD5:
equ
5
;bit #5
PTEDD4:
equ
4
;bit #4
PTEDD3:
equ
3
;bit #3
PTEDD2:
equ
2
;bit #2
PTEDD1:
equ
1
;bit #1
PTEDD0:
equ
0
;bit #0
; bit position masks
mPTEDD7:
equ
%10000000
;port E bit 7
mPTEDD6:
equ
%01000000
;port E bit 6
mPTEDD5:
equ
%00100000
;port E bit 5
mPTEDD4:
equ
%00010000
;port E bit 4
mPTEDD3:
equ
%00001000
;port E bit 3
mPTEDD2:
equ
%00000100
;port E bit 2
mPTEDD1:
equ
%00000010
;port E bit 1
mPTEDD0:
equ
%00000001
;port E bit 0
PTFD:
equ
$40
;I/O port F data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTFD7:
equ
7
;bit #7
PTFD6:
equ
6
;bit #6
PTFD5:
equ
5
;bit #5
PTFD4:
equ
4
;bit #4
PTFD3:
equ
3
;bit #3
PTFD2:
equ
2
;bit #2
PTFD1:
equ
1
;bit #1
PTFD0:
equ
0
;bit #0
; bit position masks
mPTFD7:
equ
%10000000
;port F bit 7
mPTFD6:
equ
%01000000
;port F bit 6
mPTFD5:
equ
%00100000
;port F bit 5
mPTFD4:
equ
%00010000
;port F bit 4
mPTFD3:
equ
%00001000
;port F bit 3
mPTFD2:
equ
%00000100
;port F bit 2
mPTFD1:
equ
%00000010
;port F bit 1
mPTFD0:
equ
%00000001
;port F bit 0
PTFPE:
equ
$41
;I/O port F pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTFPE7:
equ
7
;bit #7
PTFPE6:
equ
6
;bit #6
PTFPE5:
equ
5
;bit #5
PTFPE4:
equ
4
;bit #4
PTFPE3:
equ
3
;bit #3
PTFPE2:
equ
2
;bit #2
PTFPE1:
equ
1
;bit #1
PTFPE0:
equ
0
;bit #0
; bit position masks
mPTFPE7:
equ
%10000000
;port F bit 7
mPTFPE6:
equ
%01000000
;port F bit 6
mPTFPE5:
equ
%00100000
;port F bit 5
mPTFPE4:
equ
%00010000
;port F bit 4
mPTFPE3:
equ
%00001000
;port F bit 3
mPTFPE2:
equ
%00000100
;port F bit 2
mPTFPE1:
equ
%00000010
;port F bit 1
mPTFPE0:
equ
%00000001
;port F bit 0
HCS08 Family Reference Manual, Rev. 2
306
Freescale Semiconductor
Complete Equate File for MC9S08GB60
PTFSE:
equ
$42
;I/O port F slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTFSE7:
equ
7
;bit #7
PTFSE6:
equ
6
;bit #6
PTFSE5:
equ
5
;bit #5
PTFSE4:
equ
4
;bit #4
PTFSE3:
equ
3
;bit #3
PTFSE2:
equ
2
;bit #2
PTFSE1:
equ
1
;bit #1
PTFSE0:
equ
0
;bit #0
; bit position masks
mPTFSE7:
equ
%10000000
;port F bit 7
mPTFSE6:
equ
%01000000
;port F bit 6
mPTFSE5:
equ
%00100000
;port F bit 5
mPTFSE4:
equ
%00010000
;port F bit 4
mPTFSE3:
equ
%00001000
;port F bit 3
mPTFSE2:
equ
%00000100
;port F bit 2
mPTFSE1:
equ
%00000010
;port F bit 1
mPTFSE0:
equ
%00000001
;port F bit 0
PTFDD:
equ
$43
;I/O port F data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTFDD7:
equ
7
;bit #7
PTFDD6:
equ
6
;bit #6
PTFDD5:
equ
5
;bit #5
PTFDD4:
equ
4
;bit #4
PTFDD3:
equ
3
;bit #3
PTFDD2:
equ
2
;bit #2
PTFDD1:
equ
1
;bit #1
PTFDD0:
equ
0
;bit #0
; bit position masks
mPTFDD7:
equ
%10000000
;port F bit 7
mPTFDD6:
equ
%01000000
;port F bit 6
mPTFDD5:
equ
%00100000
;port F bit 5
mPTFDD4:
equ
%00010000
;port F bit 4
mPTFDD3:
equ
%00001000
;port F bit 3
mPTFDD2:
equ
%00000100
;port F bit 2
mPTFDD1:
equ
%00000010
;port F bit 1
mPTFDD0:
equ
%00000001
;port F bit 0
PTGD:
equ
$44
;I/O port G data register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTGD7:
equ
7
;bit #7
PTGD6:
equ
6
;bit #6
PTGD5:
equ
5
;bit #5
PTGD4:
equ
4
;bit #4
PTGD3:
equ
3
;bit #3
PTGD2:
equ
2
;bit #2
PTGD1:
equ
1
;bit #1
PTGD0:
equ
0
;bit #0
; bit position masks
mPTGD7:
equ
%10000000
;port G bit 7
mPTGD6:
equ
%01000000
;port G bit 6
mPTGD5:
equ
%00100000
;port G bit 5
mPTGD4:
equ
%00010000
;port G bit 4
mPTGD3:
equ
%00001000
;port G bit 3
mPTGD2:
equ
%00000100
;port G bit 2
mPTGD1:
equ
%00000010
;port G bit 1
mPTGD0:
equ
%00000001
;port G bit 0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
307
Equate File Conventions
PTGPE:
equ
$45
;I/O port G pullup enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTGPE7:
equ
7
;bit #7
PTGPE6:
equ
6
;bit #6
PTGPE5:
equ
5
;bit #5
PTGPE4:
equ
4
;bit #4
PTGPE3:
equ
3
;bit #3
PTGPE2:
equ
2
;bit #2
PTGPE1:
equ
1
;bit #1
PTGPE0:
equ
0
;bit #0
; bit position masks
mPTGPE7:
equ
%10000000
;port G bit 7
mPTGPE6:
equ
%01000000
;port G bit 6
mPTGPE5:
equ
%00100000
;port G bit 5
mPTGPE4:
equ
%00010000
;port G bit 4
mPTGPE3:
equ
%00001000
;port G bit 3
mPTGPE2:
equ
%00000100
;port G bit 2
mPTGPE1:
equ
%00000010
;port G bit 1
mPTGPE0:
equ
%00000001
;port G bit 0
PTGSE:
equ
$46
;I/O port G slew rate control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTGSE7:
equ
7
;bit #7
PTGSE6:
equ
6
;bit #6
PTGSE5:
equ
5
;bit #5
PTGSE4:
equ
4
;bit #4
PTGSE3:
equ
3
;bit #3
PTGSE2:
equ
2
;bit #2
PTGSE1:
equ
1
;bit #1
PTGSE0:
equ
0
;bit #0
; bit position masks
mPTGSE7:
equ
%10000000
;port G bit 7
mPTGSE6:
equ
%01000000
;port G bit 6
mPTGSE5:
equ
%00100000
;port G bit 5
mPTGSE4:
equ
%00010000
;port G bit 4
mPTGSE3:
equ
%00001000
;port G bit 3
mPTGSE2:
equ
%00000100
;port G bit 2
mPTGSE1:
equ
%00000010
;port G bit 1
mPTGSE0:
equ
%00000001
;port G bit 0
PTGDD:
equ
$47
;I/O port G data direction register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
PTGDD7:
equ
7
;bit #7
PTGDD6:
equ
6
;bit #6
PTGDD5:
equ
5
;bit #5
PTGDD4:
equ
4
;bit #4
PTGDD3:
equ
3
;bit #3
PTGDD2:
equ
2
;bit #2
PTGDD1:
equ
1
;bit #1
PTGDD0:
equ
0
;bit #0
; bit position masks
mPTGDD7:
equ
%10000000
;port G bit 7
mPTGDD6:
equ
%01000000
;port G bit 6
mPTGDD5:
equ
%00100000
;port G bit 5
mPTGDD4:
equ
%00010000
;port G bit 4
mPTGDD3:
equ
%00001000
;port G bit 3
mPTGDD2:
equ
%00000100
;port G bit 2
mPTGDD1:
equ
%00000010
;port G bit 1
mPTGDD0:
equ
%00000001
;port G bit 0
HCS08 Family Reference Manual, Rev. 2
308
Freescale Semiconductor
Complete Equate File for MC9S08GB60
;**** Interrupt Request Module (IRQ) ******************************************************
;*
IRQSC:
equ
$14
;IRQ status and control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
IRQEDG:
equ
5
;(bit #5) IRQ pin edge sensitivity
IRQPE:
equ
4
;(bit #4) IRQ pin enable (PTB5)
IRQF:
equ
3
;(bit #3) IRQ flag
IRQACK:
equ
2
;(bit #2) acknowledge IRQ flag
IRQIE:
equ
1
;(bit #1) IRQ pin interrupt enable
IRQMOD:
equ
0
;(bit #0) IRQ mode
; bit position masks
mIRQEDG:
equ
%00100000
;IRQ pin edge sensitivity
mIRQPE:
equ
%00010000
;IRQ pin enable (PTB5)
mIRQF:
equ
%00001000
;IRQ flag
mIRQACK:
equ
%00000100
;acknowledge IRQ flag
mIRQIE:
equ
%00000010
;IRQ pin interrupt enable
mIRQMOD:
equ
%00000001
;IRQ mode
;**** Keyboard Interrupt Module (KBI) *****************************************************
;*
KBISC:
equ
$16
;KBI status and control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
KBEDG7:
equ
7
;rise-hi/fall-low for KBIP7 pin
KBEDG6:
equ
6
;rise-hi/fall-low for KBIP6 pin
KBEDG5:
equ
5
;rise-hi/fall-low for KBIP5 pin
KBEDG4:
equ
4
;rise-hi/fall-low for KBIP4 pin
KBF:
equ
3
;KBI flag
KBACK:
equ
2
;acknowledge
KBIE:
equ
1
;KBI interrupt enable
KBIMOD:
equ
0
;KBI mode select
; bit position masks
mKBEDG7:
equ
%10000000
;rise-hi/fall-low for KBIP7 pin
mKBEDG6:
equ
%01000000
;rise-hi/fall-low for KBIP6 pin
mKBEDG5:
equ
%00100000
;rise-hi/fall-low for KBIP5 pin
mKBEDG4:
equ
%00010000
;rise-hi/fall-low for KBIP4 pin
mKBF:
equ
%00001000
;KBI flag
mKBACK:
equ
%00000100
;acknowledge
mKBIE:
equ
%00000010
;KBI interrupt enable
mKBIMOD:
equ
%00000001
;KBI mode select
KBIPE:
equ
$17
;KBI pin enable controls
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
KBIPE7:
equ
7
;bit #7
KBIPE6:
equ
6
;bit #6
KBIPE5:
equ
5
;bit #5
KBIPE4:
equ
4
;bit #4
KBIPE3:
equ
3
;bit #3
KBIPE2:
equ
2
;bit #2
KBIPE1:
equ
1
;bit #1
KBIPE0:
equ
0
;bit #0
; bit position masks
mKBIPE7:
equ
%10000000
;port A bit 7
mKBIPE6:
equ
%01000000
;port A bit 6
mKBIPE5:
equ
%00100000
;port A bit 5
mKBIPE4:
equ
%00010000
;port A bit 4
mKBIPE3:
equ
%00001000
;port A bit 3
mKBIPE2:
equ
%00000100
;port A bit 2
mKBIPE1:
equ
%00000010
;port A bit 1
mKBIPE0:
equ
%00000001
;port A bit 0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
309
Equate File Conventions
;**** Serial Communications Interface 1&2 (SCI1 & SCI2) ***********************************
;*
SCI1BDH:
equ
$18
;SCI1 baud rate register (high)
SCI2BDH:
equ
$20
;SCI2 baud rate register (high)
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
SBR12:
equ
4
;(bit #4) baud divide (high)
SBR11:
equ
3
;(bit #3) "
SBR10:
equ
2
;(bit #2) "
SBR9:
equ
1
;(bit #1) "
SBR8:
equ
0
;(bit #0) "
; bit position masks
mSBR12:
equ
%00010000
;high bits of baud rate divider
mSBR11:
equ
%00001000
; "
mSBR10:
equ
%00000100
; "
mSBR9:
equ
%00000010
; "
mSBR8:
equ
%00000001
; "
SCI1BDL:
equ
$19
;SCI1 baud rate register (low byte)
SCI2BDL:
equ
$21
;SCI2 baud rate register (low byte)
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
SBR7:
equ
7
;(bit #7) baud divide (low)
SBR6:
equ
6
;(bit #6) "
SBR5:
equ
5
;(bit #5) "
SBR4:
equ
4
;(bit #4) "
SBR3:
equ
3
;(bit #3) "
SBR2:
equ
2
;(bit #2) "
SBR1:
equ
1
;(bit #1) "
SBR0:
equ
0
;(bit #0) "
; bit position masks
mSBR7:
equ
%10000000
;low byte of baud rate divider
mSBR6:
equ
%01000000
; "
mSBR5:
equ
%00100000
; "
mSBR4:
equ
%00010000
; "
mSBR3:
equ
%00001000
; "
mSBR2:
equ
%00000100
; "
mSBR1:
equ
%00000010
; "
mSBR0:
equ
%00000001
; "
SCI1C1:
equ
$1A
;SCI1 control register 1
SCI2C1:
equ
$22
;SCI2 control register 1
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
LOOPS:
equ
7
;(bit #7) loopback mode
SCISWAI:
equ
6
;(bit #6) SCI stop in wait
RSRC:
equ
5
;(bit #5) receiver source
M:
equ
4
;(bit #4) 9/8 bit data
WAKE:
equ
3
;(bit #3) wake by addr mark/idle
ILT:
equ
2
;(bit #2) idle line type; stop/start
PE:
equ
1
;(bit #1) parity enable
PT:
equ
0
;(bit #0) parity type
; bit position masks
mLOOPS:
equ
%10000000
;loopback mode select
mSCISWAI:
equ
%01000000
;SCI stops in wait mode
mRSRC:
equ
%00100000
;receiver source
mM:
equ
%00010000
;9/8 bit data
mWAKE:
equ
%00001000
;wakeup by addr mark/idle
mILT:
equ
%00000100
;idle line type; after stop/start
mPE:
equ
%00000010
;parity enable
mPT:
equ
%00000001
;parity type even/odd
HCS08 Family Reference Manual, Rev. 2
310
Freescale Semiconductor
Complete Equate File for MC9S08GB60
SCI1C2:
equ
$1B
;SCI1 control register 2
SCI2C2:
equ
$23
;SCI2 control register 2
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
TIE:
equ
7
;(bit #7) transmit interrupt enable
TCIE:
equ
6
;(bit #6) TC interrupt enable
RIE:
equ
5
;(bit #5) receive interrupt enable
ILIE:
equ
4
;(bit #4) idle line interrupt enable
TE:
equ
3
;(bit #3) transmitter enable
RE:
equ
2
;(bit #2) receiver enable
RWU:
equ
1
;(bit #1) receiver wakeup engage
SBK:
equ
0
;(bit #0) send break
; bit position masks
mTIE:
equ
%10000000
;transmit interrupt (TDRE) enable
mTCIE:
equ
%01000000
;transmit complete interrupt enable
mRIE:
equ
%00100000
;receive interrupt (RDRF) enable
mILIE:
equ
%00010000
;idle line interrupt (ILIE) enable
mTE:
equ
%00001000
;transmitter enable
mRE:
equ
%00000100
;receiver enable
mRWU:
equ
%00000010
;receiver wakeup engage
mSBK:
equ
%00000001
;send break characters
SCI1S1:
equ
$1C
;SCI1 status register 1
SCI2S1:
equ
$24
;SCI2 status register 1
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
TDRE:
equ
7
;(bit #7) Tx data register empty
TC:
equ
6
;(bit #6) transmit complete
RDRF:
equ
5
;(bit #5) Rx data register full
IDLE:
equ
4
;(bit #4) idle line detected
OR:
equ
3
;(bit #3) Rx over run
NF:
equ
2
;(bit #2) Rx noise flag
FE:
equ
1
;(bit #1) Rx framing error
PF:
equ
0
;(bit #0) Rx parity failed
; bit position masks
mTDRE:
equ
%10000000
;transmit data register empty
mTC:
equ
%01000000
;transmit complete
mRDRF:
equ
%00100000
;receive data register full
mIDLE:
equ
%00010000
;idle line detected
mOR:
equ
%00001000
;receiver over run
mNF:
equ
%00000100
;receiver noise flag
mFE:
equ
%00000010
;receiver framing error
mPF:
equ
%00000001
;received parity failed
SCI1S2:
equ
$1D
;SCI1 status register 2
SCI2S2:
equ
$25
;SCI2 status register 2
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
RAF:
equ
0
;(bit #0) Rx active flag
; bit position masks
mRAF:
equ
%00000001
;receiver active flag
SCI1C3:
equ
$1E
;SCI1 control register 3
SCI2C3:
equ
$26
;SCI2 control register 3
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
R8:
equ
7
;(bit #7) 9th Rx bit
T8:
equ
6
;(bit #6) 9th Tx bit
TXDIR:
equ
5
;(bit #5) TxD pin direction?
ORIE:
equ
3
;(bit #3) Rx over run int. enable
NEIE:
equ
2
;(bit #2) Rx noise flag int. enable
FEIE:
equ
1
;(bit #1) Rx framing error int. enable
PEIE:
equ
0
;(bit #0) Rx parity error int. enable
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
311
Equate File Conventions
; bit position masks
mR8:
equ
%10000000
mT8:
equ
%01000000
mTXDIR:
equ
%00100000
mORIE:
equ
%00001000
mNEIE:
equ
%00000100
mFEIE:
equ
%00000010
mPEIE:
equ
%00000001
;9th receive data bit
;9th transmit data bit
;transmit pin direction?
;receiver over run int. enable
;receiver noise flag int. enable
;receiver framing error int. enable
;received parity error int. enable
SCI1D:
equ
$1F
;SCI1 data register (low byte)
SCI2D:
equ
$27
;SCI2 data register (low byte)
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
; read-only Rx data buffer
R7:
equ
7
;(bit #7) receive data bits
R6:
equ
6
;(bit #6) "
R5:
equ
5
;(bit #5) "
R4:
equ
4
;(bit #4) "
R3:
equ
3
;(bit #3) "
R2:
equ
2
;(bit #2) "
R1:
equ
1
;(bit #1) "
R0:
equ
0
;(bit #0) "
; write-only Tx data buffer
T7:
equ
7
;(bit #7) transmit data bits
T6:
equ
6
;(bit #6) "
T5:
equ
5
;(bit #5) "
T4:
equ
4
;(bit #4) "
T3:
equ
3
;(bit #3) "
T2:
equ
2
;(bit #2) "
T1:
equ
1
;(bit #1) "
T0:
equ
0
;(bit #0) "
; bit position masks
; read-only Rx data buffer
mR7:
equ
%10000000
;receive data bits
mR6:
equ
%01000000
; "
mR5:
equ
%00100000
; "
mR4:
equ
%00010000
; "
mR3:
equ
%00001000
; "
mR2:
equ
%00000100
; "
mR1:
equ
%00000010
; "
mR0:
equ
%00000001
; "
; write-only Tx data buffer
mT7:
equ
%10000000
;transmit data bits
mT6:
equ
%01000000
; "
mT5:
equ
%00100000
; "
mT4:
equ
%00010000
; "
mT3:
equ
%00001000
; "
mT2:
equ
%00000100
; "
mT1:
equ
%00000010
; "
mT0:
equ
%00000001
; "
;**** Serial Peripheral Interface (SPI) ***************************************************
;*
SPIC1:
equ
$28
;SPI control register 1
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
SPIE:
equ
7
;(bit #7) SPI interrupt enable
SPE:
equ
6
;(bit #6) SPI enable
SPTIE:
equ
5
;(bit #5) Tx error interrupt enable
MSTR:
equ
4
;(bit #4) master/slave
CPOL:
equ
3
;(bit #3) clock polarity
CPHA:
equ
2
;(bit #2) clock phase
HCS08 Family Reference Manual, Rev. 2
312
Freescale Semiconductor
Complete Equate File for MC9S08GB60
SSOE:
equ
1
LSBFE:
equ
0
; bit position masks
mSPIE:
equ
%10000000
mSPE:
equ
%01000000
mSPTIE:
equ
%00100000
mMSTR:
equ
%00010000
mCPOL:
equ
%00001000
mCPHA:
equ
%00000100
mSSOE:
equ
%00000010
mLSBFE:
equ
%00000001
;(bit #1) SS output enable
;(bit #0) LSB-first enable
;SPI interrupt enable
;SPI enable
;SPI Tx error interrupt enable
;master/slave
;clock polarity
;clock phase
;slave select output enable
;LSB-first enable
SPIC2:
equ
$29
;SPI control register 2
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
MODFEN:
equ
4
;(bit #4) mode fault enable
BIDIROE:
equ
3
;(bit #3) bi-directional enable
SPISWAI:
equ
1
;(bit #1) SPI stops in wait
SPCO:
equ
0
;(bit #0) SPI pin control
; bit position masks
mMODFEN:
equ
%00010000
;mode fault enable
mBIDIROE:
equ
%00001000
;bi-directional operation enable
mSPISWAI:
equ
%00000010
;SPI stops in wait mode
mSPCO:
equ
%00000001
;SPI pin control
SPIBR:
equ
$2A
;SPI baud
; bit numbers for use in BCLR, BSET, BRCLR,
SPPR2:
equ
6
;(bit #6)
SPPR1:
equ
5
;(bit #5)
SPPR0:
equ
4
;(bit #4)
SPR2:
equ
2
;(bit #2)
SPR1:
equ
1
;(bit #1)
SPR0:
equ
0
;(bit #0)
; bit position masks
mSPPR2:
equ
%01000000
;SPI baud
mSPPR1:
equ
%00100000
; "
mSPPR0:
equ
%00010000
; "
mSPR2:
equ
%00000100
;SPI rate
mSPR1:
equ
%00000010
; "
mSPR0:
equ
%00000001
; "
rate select
and BRSET
SPI baud rate prescale
"
"
SPI rate selact
"
"
rate prescale
select
SPIS:
equ
$2B
;SPI status register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
SPRF:
equ
7
;(bit #7) SPI Rx full flag
SPTEF:
equ
5
;(bit #5) SPI Tx error flag
MODF:
equ
4
;(bit #4) mode fault flag
; bit position masks
mSPRF:
equ
%10000000
;SPI receive buffer full flag
mSPTEF:
equ
%00100000
;SPI Tx error flag?
mMODF:
equ
%00010000
;mode fault flag
SPID:
equ
$2D
;SPI data register
;**** Analog-to-Digital Converter Module (ATD) ********************************************
;*;
ATDC:
equ
$50
;atd control tegister
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
ATDPU:
equ
7
;(bit #7) ATD power up
DJM:
equ
6
;(bit #6) justification mode; rt/left
RES8:
equ
5
;(bit #5) ATD resolution select
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
313
Equate File Conventions
SGN:
equ
4
PRS3:
equ
3
PRS2:
equ
2
PRS1:
equ
1
PRS0:
equ
0
; bit position masks
mATDPU:
equ
%10000000
mDJM:
equ
%01000000
mRES8:
equ
%00100000
mSGN:
equ
%00010000
mPRS3:
equ
%00001000
mPRS2:
equ
%00000100
mPRS1:
equ
%00000010
mPRS0:
equ
%00000001
;(bit
;(bit
;(bit
;(bit
;(bit
#4)
#3)
#2)
#1)
#0)
signed result select
prescaler rate select (high)
prescaler rate select
prescaler rate select
prescaler rate select (low)
;ATD power up
;data justification mode; right/left
;ATD resolution select
;signed result select
;prescaler rate select (high)
;prescaler rate select
;prescaler rate select
;prescaler rate select (low)
ATDSC:
equ
$51
;atd ststus and control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CCF:
equ
7
;(bit #7) conversion complete flag
ATDIE:
equ
6
;(bit #6) ATD interrupt enable
ATDCO:
equ
5
;(bit #5) ATD continuous conversion
ATDCH4:
equ
4
;(bit #4) ATD input channel select (high)
ATDCH3:
equ
3
;(bit #3) ATD input channel select
ATDCH2:
equ
2
;(bit #2) ATD input channel select
ATDCH1:
equ
1
;(bit #1) ATD input channel select
ATDCH0:
equ
0
;(bit #0) ATD input channel select (low)
; bit position masks
mCCF:
equ
%10000000
;conversion complete flag
mATDIE:
equ
%01000000
;ATD interrupt enable
mATDCO:
equ
%00100000
;ATD continuous conversion
mATDCH4:
equ
%00010000
;ATD input channel select (high)
mATDCH3:
equ
%00001000
;prescaler rate select
mATDCH2:
equ
%00000100
;prescaler rate select
mATDCH1:
equ
%00000010
;prescaler rate select
mATDCH0:
equ
%00000001
;prescaler rate select (low)
ATDPE:
equ
$54
;ATD pin enable register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
ATDPE7:
equ
7
;(bit #7)
ATDPE6:
equ
6
;(bit #6)
ATDPE5:
equ
5
;(bit #5)
ATDPE4:
equ
4
;(bit #4)
ATDPE3:
equ
3
;(bit #3)
ATDPE2:
equ
2
;(bit #2)
ATDPE1:
equ
1
;(bit #1)
ATDPE0:
equ
0
;(bit #0)
; bit position masks
mATDPE7:
equ
%10000000
;ATDPE bit 7
mATDPE6:
equ
%01000000
;ATDPE bit 6
mATDPE5:
equ
%00100000
;ATDPE bit 5
mATDPE4:
equ
%00010000
;ATDPE bit 4
mATDPE3:
equ
%00001000
;ATDPE bit 3
mATDPE2:
equ
%00000100
;ATDPE bit 2
mATDPE1:
equ
%00000010
;ATDPE bit 1
mATDPE0:
equ
%00000001
;ATDPE bit 0
ATDRH:
ATDRL:
equ
equ
$52
$53
;ATD result register (high)
;ATD result register (low)
HCS08 Family Reference Manual, Rev. 2
314
Freescale Semiconductor
Complete Equate File for MC9S08GB60
;****
;*;
IICA:
Inter-Integrated Circuit Module (IIC) ************************************************
equ
$58
;IIC address register
IICF:
equ
$59
;IIC frequency divider register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
MULT1:
equ
7
;(bit #7) IIC multiply factor (high)
MULT0:
equ
6
;(bit #6) IIC multiply factor (low)
ICR5:
equ
5
;(bit #5) IIC Divider and Hold bit-5
ICR4:
equ
4
;(bit #4) IIC Divider and Hold bit-4
ICR3:
equ
3
;(bit #3) IIC Divider and Hold bit-3
ICR2:
equ
2
;(bit #2) IIC Divider and Hold bit-2
ICR1:
equ
1
;(bit #1) IIC Divider and Hold bit-1
ICR0:
equ
0
;(bit #0) IIC Divider and Hold bit-0
; bit position masks
mMULT1:
equ
%10000000
;IIC multiply factor (high)
mMULT0:
equ
%01000000
;IIC multiply factor (low)
mICR5:
equ
%00100000
;IIC Divider and Hold bit-5
mICR4:
equ
%00010000
;IIC Divider and Hold bit-4
mICR3:
equ
%00001000
;IIC Divider and Hold bit-3
mICR2:
equ
%00000100
;IIC Divider and Hold bit-2
mICR1:
equ
%00000010
;IIC Divider and Hold bit-1
mICR0:
equ
%00000001
;IIC Divider and Hold bit-0
IICC:
equ
$5A
;IIC control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
IICEN:
equ
7
;(bit #7) IIC enable bit
IICIE:
equ
6
;(bit #6) IIC interrupt enable bit
MST:
equ
5
;(bit #5) IIC master mode select bit
TX:
equ
4
;(bit #4) IIC transmit mode select bit
TXAK:
equ
3
;(bit #3) IIC transmit acknowledge bit
RSTA:
equ
2
;(bit #2) IIC repeat start bit
; bit position masks
mIICEN:
equ
%10000000
;IIC enable
mIICIE:
equ
%01000000
;IIC interrupt enable bit
mMST:
equ
%00100000
;IIC master mode select bit
mTX:
equ
%00010000
;IIC transmit mode select bit
mTXAK:
equ
%00001000
;IIC transmit acknowledge bit
mRSTA:
equ
%00000100
;IIC repeat start bit
IICS:
equ
$5B
;IIC status register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
TCF:
equ
7
;(bit #7) IIC transfer complete flag bit
IIAS:
equ
6
;(bit #6) IIC addressed as slave bit
BUSY:
equ
5
;(bit #5) IIC bus busy bit
ARBL:
equ
4
;(bit #4) IIC arbitration lost bit
SRW:
equ
2
;(bit #2) IIC slave read/write bit
IICIF:
equ
1
;(bit #1) IIC interrupt flag bit
RXAK:
equ
0
;(bit #0) IIC receive acknowledge bit
; bit position masks
mTCF:
equ
%10000000
;IIC transfer complete flag bit
mIIAS:
equ
%01000000
;IIC addressed as slave bit
mBUSY:
equ
%00100000
;IIC bus busy bit
mARBL:
equ
%00010000
;IIC arbitration lost bit
mSRW:
equ
%00000100
;IIC slave read/write bit
mIICIF:
equ
%00000010
;IIC interrupt flag bit
mRXAK:
equ
%00000001
;IIC receive acknowledge bit
IICD:
equ
$5C
;IIC data I/O register bits 7:0
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
315
Equate File Conventions
;**** Timer/PWM Module 1 (TPM1) ***** TPM1 has 3 channels *********************************
;**** Timer/PWM Module 2 (TPM2) ***** TPM2 has 5 channels *********************************
;*
TPM1SC:
equ
$30
;TPM1 status and control register
TPM2SC:
equ
$60
;TPM2 status and control register
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
TOF:
equ
7
;(bit #7) tomer overflow flag
TOIE:
equ
6
;(bit #6) TOF interrupt enable
CPWMS:
equ
5
;(bit #5) centered PWM select
CLKSB:
equ
4
;(bit #4) clock select bits
CLKSA:
equ
3
;(bit #3) "
PS2:
equ
2
;(bit #2) prescaler bits
PS1:
equ
1
;(bit #1) "
PS0:
equ
0
;(bit #0) "
; bit position masks
mTOF:
equ
%10000000
;timer overflow flag
mTOIE:
equ
%01000000
;timer overflow interrupt enable
mCPWMS:
equ
%00100000
;center-aligned PWM select
mCLKSB:
equ
%00010000
;clock source select bits
mCLKSA:
equ
%00001000
; "
mPS2:
equ
%00000100
;prescaler bits
mPS1:
equ
%00000010
; "
mPS0:
equ
%00000001
; "
TPM1CNTH:
TPM1CNTL:
TPM1MODH:
TPM1MODL:
equ
equ
equ
equ
$31
$32
$33
$34
;TPM1
;TPM1
;TPM1
;TPM1
counter (high half)
counter (low half)
modulo register (high half)
modulo register(low half)
TPM2CNTH:
TPM2CNTL:
TPM2MODH:
TPM2MODL:
equ
equ
equ
equ
$61
$62
$63
$64
;TPM2
;TPM2
;TPM2
;TPM2
counter (high half)
counter (low half)
modulo register (high half)
modulo register(low half)
TPM1C0SC:
equ
$35
;TPM1 channel 0 status and control
TPM2C0SC:
equ
$65
;TPM2 channel 0 status and control
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CH0F:
equ
7
;(bit #7) channel 0 flag
CH0IE:
equ
6
;(bit #6) ch 0 interrupt enable
MS0B:
equ
5
;(bit #5) mode select B
MS0A:
equ
4
;(bit #4) mode select A
ELS0B:
equ
3
;(bit #3) edge/level select B
ELS0A:
equ
2
;(bit #2) edge/level select A
; bit position masks
mCH0F:
equ
%10000000
;channel 0 flag
mCH0IE:
equ
%01000000
;ch 0 interrupt enable
mMS0B:
equ
%00100000
;mode select B
mMS0A:
equ
%00010000
;mode select A
mELS0B:
equ
%00001000
;edge/level select B
mELS0A:
equ
%00000100
;edge/level select A
TPM1C0VH:
TPM1C0VL:
equ
equ
$36
$37
;TPM1 channel 0 value register (high)
;TPM1 channel 0 value register (low)
TPM2C0VH:
TPM2C0VL:
equ
equ
$66
$67
;TPM2 channel 0 value register (high)
;TPM2 channel 0 value register (low)
TPM1C1SC:
TPM2C1SC:
equ
equ
$38
$68
;TPM1 channel 1 status and control
;TPM2 channel 1 status and control
HCS08 Family Reference Manual, Rev. 2
316
Freescale Semiconductor
Complete Equate File for MC9S08GB60
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CH1F:
equ
7
;(bit #7) channel 1 flag
CH1IE:
equ
6
;(bit #6) ch 1 interrupt enable
MS1B:
equ
5
;(bit #5) mode select B
MS1A:
equ
4
;(bit #4) mode select A
ELS1B:
equ
3
;(bit #3) edge/level select B
ELS1A:
equ
2
;(bit #2) edge/level select A
; bit position masks
mCH1F:
equ
%10000000
;channel 1 flag
mCH1IE:
equ
%01000000
;ch 1 interrupt enable
mMS1B:
equ
%00100000
;mode select B
mMS1A:
equ
%00010000
;mode select A
mELS1B:
equ
%00001000
;edge/level select B
mELS1A:
equ
%00000100
;edge/level select A
TPM1C1VH:
TPM1C1VL:
equ
equ
$39
$3A
;TPM1 channel 1 value register (high)
;TPM1 channel 1 value register (low)
TPM2C1VH:
TPM2C1VL:
equ
equ
$69
$6A
;TPM2 channel 1 value register (high)
;TPM2 channel 1 value register (low)
TPM1C2SC:
equ
$3B
;TPM1 channel 2 status and control
TPM2C2SC:
equ
$6B
;TPM2 channel 2 status and control
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CH2F:
equ
7
;(bit #7) channel 2 flag
CH2IE:
equ
6
;(bit #6) ch 2 interrupt enable
MS2B:
equ
5
;(bit #5) mode select B
MS2A:
equ
4
;(bit #4) mode select A
ELS2B:
equ
3
;(bit #3) edge/level select B
ELS2A:
equ
2
;(bit #2) edge/level select A
; bit position masks
mCH2F:
equ
%10000000
;channel 2 flag
mCH2IE:
equ
%01000000
;ch 2 interrupt enable
mMS2B:
equ
%00100000
;mode select B
mMS2A:
equ
%00010000
;mode select A
mELS2B:
equ
%00001000
;edge/level select B
mELS2A:
equ
%00000100
;edge/level select A
TPM1C2VH:
TPM1C2VL:
equ
equ
$3C
$3D
;TPM1 channel 2 value register (high)
;TPM1 channel 2 value register (low)
TPM2C2VH:
TPM2C2VL:
equ
equ
$6C
$6D
;TPM2 channel 1 value register (high)
;TPM2 channel 1 value register (low)
TPM2C3SC:
equ
$6E
;TPM2 channel 3 status and control
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CH3F:
equ
7
;(bit #7) channel 3 flag
CH3IE:
equ
6
;(bit #6) ch 3 interrupt enable
MS3B:
equ
5
;(bit #5) mode select B
MS3A:
equ
4
;(bit #4) mode select A
ELS3B:
equ
3
;(bit #3) edge/level select B
ELS3A:
equ
2
;(bit #2) edge/level select A
; bit position masks
mCH3F:
equ
%10000000
;channel 3 flag
mCH3IE:
equ
%01000000
;ch 3 interrupt enable
mMS3B:
equ
%00100000
;mode select B
mMS3A:
equ
%00010000
;mode select A
mELS3B:
equ
%00001000
;edge/level select B
mELS3A:
equ
%00000100
;edge/level select A
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
317
Equate File Conventions
TPM2C3VH:
TPM2C3VL:
equ
equ
$6F
$70
;TPM2 channel 1 value register (high)
;TPM2 channel 1 value register (low)
TPM2C4SC:
equ
$71
;TPM2 channel 4 status and control
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CH4F:
equ
7
;(bit #7) channel 4 flag
CH4IE:
equ
6
;(bit #6) ch 4 interrupt enable
MS4B:
equ
5
;(bit #5) mode select B
MS4A:
equ
4
;(bit #4) mode select A
ELS4B:
equ
3
;(bit #3) edge/level select B
ELS4A:
equ
2
;(bit #2) edge/level select A
; bit position masks
mCH4F:
equ
%10000000
;channel 4 flag
mCH4IE:
equ
%01000000
;ch 4 interrupt enable
mMS4B:
equ
%00100000
;mode select B
mMS4A:
equ
%00010000
;mode select A
mELS4B:
equ
%00001000
;edge/level select B
mELS4A:
equ
%00000100
;edge/level select A
TPM2C4VH:
TPM2C4VL:
equ
equ
$72
$73
;TPM2 channel 1 value register (high)
;TPM2 channel 1 value register (low)
**** Internal Clock Generator Module (ICG) ************************************************
;*
ICGC1:
equ
$48
;ICG control register 1
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
RANGE:
equ
6
;(bit #6) frequency range select
REFS:
equ
5
;(bit #5) reference select
CLKS1:
equ
4
;(bit #4) clock select bit 1
CLKS0:
equ
3
;(bit #3) clock select bit 0
OSCSTEN:
equ
2
;(bit #2) oscillator runs in stop
; bit position masks
mRANGE:
equ
%01000000
;frequency range select
mREFS:
equ
%00100000
;reference select
mCLKS1:
equ
%00010000
;clock mode select (bit-1)
mCLKS0:
equ
%00001000
;clock mode select (bit 0)
mOSCSTEN:
equ
%00000100
;enable oscillator in stop mode
ICGC2:
equ
$49
;ICG control register 2
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
LOLRE:
equ
7
;(bit #7) loss of lock reset enable
MFD2:
equ
6
;(bit #6) multiplication factor div
MFD1:
equ
5
;(bit #5) "
MFD0:
equ
4
;(bit #4) "
LOCRE:
equ
3
;(bit #3) loss of clock reset enable
RFD2:
equ
2
;(bit #2) reference divider
RFD1:
equ
1
;(bit #1) "
RFD0:
equ
0
;(bit #0) "
; bit position masks
mLOLRE:
equ
%10000000
;loss of lock reset enable
mMFD2:
equ
%01000000
;multiplication factor divider
mMFD1:
equ
%00100000
; "
mMFD0:
equ
%00010000
; "
mLOCRE:
equ
%00001000
;loss of clock reset enable
mRFD2:
equ
%00000100
;reference divider bits
mRFD1:
equ
%00000010
; "
mRFD0:
equ
%00000001
; "
ICGS1:
equ
$4A
;ICG status register 1
HCS08 Family Reference Manual, Rev. 2
318
Freescale Semiconductor
Complete Equate File for MC9S08GB60
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
CLKST1:
equ
7
;(bit #7) clock mode status 1
CLKST0:
equ
6
;(bit #6) clock mode status 0
REFST:
equ
5
;(bit #5) reference clock status
LOLS:
equ
4
;(bit #4) loss of lock status
LOCK:
equ
3
;(bit #3) FLL lock status
LOCS:
equ
2
;(bit #2) loss of clock status
ERCS:
equ
1
;(bit #1) ext ref clk status
ICGIF:
equ
0
;(bit #0) ICG interrupt flag
; bit position masks
mCLKST1:
equ
%10000000
;clock mode status 1
mCLKST0:
equ
%01000000
;clock mode status 0
mREFST:
equ
%00100000
;reference clock status
mLOLS:
equ
%00010000
;loss of lock status
mLOCK:
equ
%00001000
;FLL lock status
mLOCS:
equ
%00000100
;loss of clock status
mERCS:
equ
%00000010
;ext ref clk status
mICGIF:
equ
%00000001
;ICG interrupt flag
ICGS2:
equ
$4B
;ICG status register 2
; bit numbers for use in BCLR, BSET, BRCLR, and BRSET
DCOS:
equ
0
;(bit #0) DCO Clock Stable
; bit position masks
mDCOS:
equ
%00000001
;DCO Clock Stable
ICGFLTU:
ICGFLTL:
equ
equ
$4C
$4D
;ICG filter register (upper 4 bits in bits 3:0)
;ICG filter register (lower 8 bits)
ICGTRM:
equ
$4E
;ICG trim register
;**** System Integration Module (SIM) *****************************************************
;*
SRS:
equ
$1800
;SIM reset status register
; bit position masks
mPOR:
equ
%10000000
;power-on reset
mPIN:
equ
%01000000
;external reset pin
mCOP:
equ
%00100000
;COP watchdog timed out
mILOP:
equ
%00010000
;illegal opcode
mICG:
equ
%00000100
;illegal address access
mLVD:
equ
%00000010
;low-voltage detect
SBDFR:
equ
$1801
; bit position masks
mBDFR:
equ
%00000001
;system BDM reset register
SOPT:
equ
$1802
; bit position masks
mCOPE:
equ
%10000000
mCOPT:
equ
%01000000
mSTOPE:
equ
%00100000
mBKGDPE:
equ
%00000010
;SIM options register (write once)
SDIDH:
equ
$1806
SDIDL:
equ
$1807
; bit position masks within SDIDH
mREV3:
equ
%10000000
mREV2:
equ
%01000000
mREV1:
equ
%00100000
mREV0:
equ
%00010000
;system device identification 1 register (read-only)
;rev3,2,1,0 + 12-bit ID. GB60 ID = $002
;BDM force reset
;COP watchdog enable
;COP time-out select
;stop enable
;BDM pin enable
;device
;device
;device
;device
revision
revision
revision
revision
identification (high)
identification
identification
identification (low)
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
319
Equate File Conventions
;**** Power Management and Control Module (PMC) *******************************************
;*
SRTISC:
equ
$1808
;System RTI ststus and control register
; bit position masks
mRTIF:
equ
%10000000
;real-time interrupt flag
mRTIACK:
equ
%01000000
;real-time interrupt acknowledge
mRTICLKS:
equ
%00100000
;real-time interrupt clock select
mRTIE:
equ
%00010000
;real-time interrupt enable
mRTIS2:
equ
%00000100
;real-time interrupt delay select (high)
mRTIS1:
equ
%00000010
;real-time interrupt delay select
mRTIS0:
equ
%00000001
;real-time interrupt delay select (low)
SPMSC1:
equ
$1809
; bit position masks
mLVDF:
equ
%10000000
mLVDACK:
equ
%01000000
mLVDIE:
equ
%00100000
mLVDRE:
equ
%00010000
mLVDSE:
equ
%00001000
mLVDE:
equ
%00000100
;System power management status and control 1 register
SPMSC2:
equ
$180A
; bit position masks
mLVWF:
equ
%10000000
mLVWACK:
equ
%01000000
mLVDV:
equ
%00100000
mLVWV:
equ
%00010000
mPPDF:
equ
%00001000
mPPDACK:
equ
%00000100
mPDC:
equ
%00000010
mPPDC:
equ
%00000001
;System power management status and control 2 register
;**** Debug
;*
DBGCAH:
DBGCAL:
DBGCBH:
DBGCBL:
DBGFH:
DBGFL:
Module (DBG)
equ
equ
equ
equ
equ
equ
;low
;LVD
;LVD
;LVD
;LDV
;LVD
voltage detect flag
interrupt acknowledge
interrupt enable
reset enable (write once bit)
stop enable (write once bit)
enable (write once bit)
;low voltage warning flag
;low voltage warning acknowledge
;low voltage detect voltage select
;low voltage warning voltage select
;partial power down flag
;partial power down acknowledge
;power down control
;partial power down control
******************************************************************
$1810
$1811
$1812
$1813
$1814
$1815
;DBG
;DBG
;DBG
;DBG
;DBG
;DBG
comparator register A
comparator register A
comparator register B
comparator register B
FIFO register (high)
FIFO register (low)
DBGC:
equ
$1816
; bit position masks
mDBGEN:
equ
%10000000
mARM:
equ
%01000000
mTAG:
equ
%00100000
mBRKEN:
equ
%00010000
mRWA:
equ
%00001000
mRWAEN:
equ
%00000100
mRWB:
equ
%00000010
mRWBEN:
equ
%00000001
;DBG control register
DBGT:
equ
$1817
; bit position masks
mTRGSEL:
equ
%10000000
mBEGIN:
equ
%01000000
mTRG3:
equ
%00001000
mTRG2:
equ
%00000100
mTRG1:
equ
%00000010
mTRG0:
equ
%00000001
;DBG trigger register
(high)
(low)
(high)
(low)
;debug module enable
;arm control
;tag/force select
;break enable
;R/W compare A value
;R/W compare A enable
;R/W compare B value
;R/W compare B enable
;trigger on opcode/access
;begin/end trigger
;trigger mode bits
; "
; "
; "
HCS08 Family Reference Manual, Rev. 2
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Freescale Semiconductor
Complete Equate File for MC9S08GB60
DBGS:
equ
$1818
; bit position masks
mAF:
equ
%10000000
mBF:
equ
%01000000
mARMF:
equ
%00100000
mCNT3:
equ
%00001000
mCNT2:
equ
%00000100
mCNT1:
equ
%00000010
mCNT0:
equ
%00000001
;DBG status register
;trigger A match flag
;trigger B match flag
;arm flag
;count of items in FIFO (high)
; "
; "
;count of items in FIFO (low)
;**** Flash Module (FLASH) ****************************************************************
;*
FCDIV:
equ
$1820
;Flash clock divider register
; bit position masks
mDIVLD:
equ
%10000000
;clock divider loaded
mPRDIV8:
equ
%01000000
;enable prescale by 8
mDIV5:
equ
%00100000
;flash clock divider bits (high)
mDIV4:
equ
%00010000
; "
mDIV3:
equ
%00001000
; "
mDIV2:
equ
%00000100
; "
mDIV1:
equ
%00000010
; "
mDIV0:
equ
%00000001
;flash clock divider bits (low)
FOPT:
equ
$1821
; bit position masks
mKEYEN:
equ
%10000000
mFNORED
equ
%01000000
mSEC01:
equ
%00000010
mSEC00:
equ
%00000001
;Flash options register
FCNFG:
equ
$1823
; bit position masks
mKEYACC:
equ
%00100000
;Flash configuration register
FPROT:
equ
$1824
; bit position masks
mFPOPEN:
equ
%10000000
mFPDIS:
equ
%01000000
mFPS2:
equ
%00100000
mFPS1:
equ
%00010000
mFPS0:
equ
%00001000
;Flash protection register
;enable backdoor key to security
;Vector redirection enable
;security state code (high)
;security state code (low)
;enable security key writing
;open unprotected flash for program/erase
;flash protection disable
;flash protect size select (high)
;flash protect size select
;flash protect size select (low)
FSTAT:
equ
$1825
; bit position masks
mFCBEF:
equ
%10000000
mFCCF:
equ
%01000000
mFPVIOL:
equ
%00100000
mFACCERR:
equ
%00010000
mFBLANK:
equ
%00000100
;Flash status register
FCMD:
equ
$1826
; bit position masks
mFCMD7:
equ
%10000000
mFCMD6:
equ
%01000000
mFCMD5:
equ
%00100000
mFCMD4:
equ
%00010000
mFCMD3:
equ
%00001000
mFCMD2:
equ
%00000100
mFCMD1:
equ
%00000010
mFCMD0:
equ
%00000001
;Flash command register
;flash
;flash
;flash
;flash
;flash
command buffer empty flag
command complete flag
protection violation
access error
verified as all blank (erased =$ff) flag
;Flash command (high)
; "
; "
; "
; "
; "
; "
;Flash command (low)
HCS08 Family Reference Manual, Rev. 2
Freescale Semiconductor
321
Equate File Conventions
; command codes
mBlank:
equ
mByteProg:
equ
mBurstProg: equ
mPageErase: equ
mMassErase: equ
$05
$20
$25
$40
$41
;Blank Check command
;Byte Program command
;Burst Program command
;Page Erase command
;Mass Erase command
;**** Flash non-volatile register images **************************************************
;*
NVBACKKEY:
equ
$FFB0
;8-byte backdoor comparison key
; comparison key in $FFB0 through $FFB7
; following 2 registers transfered from flash to working regs at reset
NVPROT:
equ
$FFBD
;NV flash protection byte
; NVPROT transfers to FPROT on reset
NVICGTRIM:
equ
$FFBE
;NV ICG Trim Setting
; ICG trim value measured during factory test. User software optionally
; copies to ICGTRM during initialization.
NVOPT:
equ
$FFBF
;NV flash options byte
; NVFEOPT transfers to FOPT on reset
;****
END
*********************************************************************************
HCS08 Family Reference Manual, Rev. 2
322
Freescale Semiconductor
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HCS08RMv1/D
Rev. 2, 05/2007
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