Freescale Semiconductor HCS12 User manual

HCS12
Microcontrollers
freescale.com
S12CPUV2
Reference Manual
S12CPUV2
Rev. 4.0
03/2006

S12CPUV2 Reference Manual, Rev. 4.0
Freescale Semiconductor 3
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© Freescale Semiconductor, Inc., 2005. All rights reserved.
S12CPUV2
Reference Manual
To provide the most up-to-date information, the revision of our documents on the World Wide Web will be
the most current. Your printed copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://www.freescale.com
The following revision history table summarizes changes contained in this document.
Revision History
Revision
Number Date Summary of Changes
3.0 April, 2002 Incorporated information covering HCS12 Family of 16-bit MCUs throughout the book.
4.0 March, 2006 Reformatted to Freescale publication standards.
Corrected mistake in ANDCC/TAP descriptions (Instruction Glossary).
Corrected mistake in MEM description (Instruction Glossary).

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Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Section 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Section 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Section 3. Addressing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Section 4. Instruction Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
Section 5. Instruction Set Overview . . . . . . . . . . . . . . . . . . . . . . .55
Section 6. Instruction Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . .87
Section 7. Exception Processing. . . . . . . . . . . . . . . . . . . . . . . . .311
Section 8. Instruction Queue . . . . . . . . . . . . . . . . . . . . . . . . . . .323
Section 9. Fuzzy Logic Support. . . . . . . . . . . . . . . . . . . . . . . . . .337
Appendix A. Instruction Reference. . . . . . . . . . . . . . . . . . . . . . .375
Appendix B. M68HC11 to CPU12 Upgrade Path. . . . . . . . . . . . .403
Appendix C. High-Level Language Support. . . . . . . . . . . . . . . .425
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .433
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List of Sections

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Section 1. Introduction
1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
1.3 Symbols and Notation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.3.1 Abbreviations for System Resources . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.3.2 Memory and Addressing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
1.3.3 Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
1.3.4 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Section 2. Overview
2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
2.2 Programming Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
2.2.1 Accumulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
2.2.2 Index Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
2.2.3 Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
2.2.4 Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
2.2.5 Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
2.2.5.1 S Control Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
2.2.5.2 X Mask Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
2.2.5.3 H Status Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
2.2.5.4 I Mask Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
2.2.5.5 N Status Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
2.2.5.6 Z Status Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
2.2.5.7 V Status Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
2.2.5.8 C Status Bit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
2.3 Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
2.4 Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
2.5 Instruction Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
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Section 3. Addressing Modes
3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.2 Mode Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.3 Effective Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.4 Inherent Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
3.5 Immediate Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
3.6 Direct Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
3.7 Extended Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
3.8 Relative Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
3.9 Indexed Addressing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
3.9.1 5-Bit Constant Offset Indexed Addressing . . . . . . . . . . . . . . . . . . . . . .37
3.9.2 9-Bit Constant Offset Indexed Addressing . . . . . . . . . . . . . . . . . . . . . .37
3.9.3 16-Bit Constant Offset Indexed Addressing . . . . . . . . . . . . . . . . . . . . .38
3.9.4 16-Bit Constant Indirect Indexed Addressing. . . . . . . . . . . . . . . . . . . .38
3.9.5 Auto Pre/Post Decrement/Increment Indexed Addressing. . . . . . . . . .39
3.9.6 Accumulator Offset Indexed Addressing . . . . . . . . . . . . . . . . . . . . . . .40
3.9.7 Accumulator D Indirect Indexed Addressing . . . . . . . . . . . . . . . . . . . .41
3.10 Instructions Using Multiple Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
3.10.1 Move Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
3.10.2 Bit Manipulation Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
3.11 Addressing More than 64 Kbytes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Section 4. Instruction Queue
4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
4.2 Queue Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
4.2.1 Original M68HC12 Queue Implementation. . . . . . . . . . . . . . . . . . . . . .48
4.2.2 HCS12 Queue Implementation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
4.3 Data Movement in the Queue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
4.3.1 No Movement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
4.3.2 Latch Data from Bus (Applies Only to the M68HC12 Queue) . . . . . . .49
4.3.3 Advance and Load from Data Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
4.3.4 Advance and Load from Buffer (Applies Only to M68HC12 Queue) . .49
4.4 Changes in Execution Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
4.4.1 Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
4.4.2 Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
4.4.3 Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

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4.4.3.1 Short Branches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
4.4.3.2 Long Branches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52
4.4.3.3 Bit Condition Branches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
4.4.3.4 Loop Primitives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
4.4.4 Jumps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Section 5. Instruction Set Overview
5.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
5.2 Instruction Set Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
5.3 Load and Store Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
5.4 Transfer and Exchange Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
5.5 Move Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
5.6 Addition and Subtraction Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
5.7 Binary-Coded Decimal Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
5.8 Decrement and Increment Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . .61
5.9 Compare and Test Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
5.10 Boolean Logic Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
5.11 Clear, Complement, and Negate Instructions. . . . . . . . . . . . . . . . . . . . . .63
5.12 Multiplication and Division Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . .64
5.13 Bit Test and Manipulation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . .65
5.14 Shift and Rotate Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
5.15 Fuzzy Logic Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
5.15.1 Fuzzy Logic Membership Instruction . . . . . . . . . . . . . . . . . . . . . . . . . .67
5.15.2 Fuzzy Logic Rule Evaluation Instructions. . . . . . . . . . . . . . . . . . . . . . .67
5.15.3 Fuzzy Logic Weighted Average Instruction . . . . . . . . . . . . . . . . . . . . .68
5.16 Maximum and Minimum Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
5.17 Multiply and Accumulate Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
5.18 Table Interpolation Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
5.19 Branch Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73
5.19.1 Short Branch Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
5.19.2 Long Branch Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
5.19.3 Bit Condition Branch Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
5.20 Loop Primitive Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
5.21 Jump and Subroutine Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

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5.22 Interrupt Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
5.23 Index Manipulation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81
5.24 Stacking Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
5.25 Pointer and Index Calculation Instructions . . . . . . . . . . . . . . . . . . . . . . . .83
5.26 Condition Code Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84
5.27 Stop and Wait Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
5.28 Background Mode and Null Operations . . . . . . . . . . . . . . . . . . . . . . . . . .86
Section 6. Instruction Glossary
6.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
6.2 Glossary Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
6.3 Condition Code Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
6.4 Object Code Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
6.5 Source Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
6.6 Cycle-by-Cycle Execution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
6.7 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
Section 7. Exception Processing
7.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
7.2 Types of Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
7.3 Exception Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312
7.4 Resets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
7.4.1 Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
7.4.2 External Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
7.4.3 COP Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
7.4.4 Clock Monitor Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .314
7.5 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
7.5.1 Non-Maskable Interrupt Request (XIRQ) . . . . . . . . . . . . . . . . . . . . . .315
7.5.2 Maskable Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
7.5.3 Interrupt Recognition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .316
7.5.4 External Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317
7.5.5 Return-from-Interrupt Instruction (RTI). . . . . . . . . . . . . . . . . . . . . . . .317
7.6 Unimplemented Opcode Trap. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317
7.7 Software Interrupt Instruction (SWI) . . . . . . . . . . . . . . . . . . . . . . . . . . . .318

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7.8 Exception Processing Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .318
7.8.1 Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .318
7.8.2 Reset Exception Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320
7.8.3 Interrupt and Unimplemented Opcode Trap Exception Processing . .320
Section 8. Instruction Queue
8.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .323
8.2 External Reconstruction of the Queue . . . . . . . . . . . . . . . . . . . . . . . . . .323
8.3 Instruction Queue Status Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .324
8.3.1 HCS12 Timing Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .324
8.3.2 M68HC12 Timing Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .325
8.3.3 Null (Code 0:0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .327
8.3.4 LAT — Latch Data from Bus (Code 0:1). . . . . . . . . . . . . . . . . . . . . . .327
8.3.5 ALD — Advance and Load from Data Bus (Code 1:0). . . . . . . . . . . .327
8.3.6 ALL — Advance and Load from Latch (Code 1:1) . . . . . . . . . . . . . . .327
8.3.7 INT — Interrupt Sequence Start (Code 0:1). . . . . . . . . . . . . . . . . . . .327
8.3.8 SEV — Start Instruction on Even Address (Code 1:0). . . . . . . . . . . .328
8.3.9 SOD — Start Instruction on Odd Address (Code 1:1) . . . . . . . . . . . .328
8.4 Queue Reconstruction (for HCS12) . . . . . . . . . . . . . . . . . . . . . . . . . . . .328
8.4.1 Queue Reconstruction Registers (for HCS12) . . . . . . . . . . . . . . . . . .329
8.4.1.1 fetch_add Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .329
8.4.1.2 st1_add, st1_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .329
8.4.1.3 st2_add, st2_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .329
8.4.1.4 st3_add, st3_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .329
8.4.2 Reconstruction Algorithm (for HCS12). . . . . . . . . . . . . . . . . . . . . . . .330
8.5 Queue Reconstruction (for M68HC12) . . . . . . . . . . . . . . . . . . . . . . . . . .331
8.5.1 Queue Reconstruction Registers (for M68HC12). . . . . . . . . . . . . . . .331
8.5.1.1 in_add, in_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .332
8.5.1.2 fetch_add, fetch_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . .332
8.5.1.3 st1_add, st1_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .332
8.5.1.4 st2_add, st2_dat Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .332
8.5.2 Reconstruction Algorithm (for M68HC12). . . . . . . . . . . . . . . . . . . . . .332
8.5.2.1 LAT Decoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333
8.5.2.2 ALD Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333
8.5.2.3 ALL Decoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333
8.6 Instruction Tagging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .335
Section 9. Fuzzy Logic Support

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9.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .337
9.2 Fuzzy Logic Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338
9.2.1 Fuzzification (MEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
9.2.2 Rule Evaluation (REV and REVW). . . . . . . . . . . . . . . . . . . . . . . . . . .342
9.2.3 Defuzzification (WAV). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344
9.3 Example Inference Kernel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .345
9.4 MEM Instruction Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347
9.4.1 Membership Function Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . .347
9.4.2 Abnormal Membership Function Definitions. . . . . . . . . . . . . . . . . . . .349
9.4.2.1 Abnormal Membership Function Case 1 . . . . . . . . . . . . . . . . . . . .351
9.4.2.2 Abnormal Membership Function Case 2 . . . . . . . . . . . . . . . . . . . .352
9.4.2.3 Abnormal Membership Function Case 3 . . . . . . . . . . . . . . . . . . . .352
9.5 REV and REVW Instruction Details . . . . . . . . . . . . . . . . . . . . . . . . . . . .353
9.5.1 Unweighted Rule Evaluation (REV) . . . . . . . . . . . . . . . . . . . . . . . . . .353
9.5.1.1 Set Up Prior to Executing REV. . . . . . . . . . . . . . . . . . . . . . . . . . . .353
9.5.1.2 Interrupt Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .355
9.5.1.3 Cycle-by-Cycle Details for REV . . . . . . . . . . . . . . . . . . . . . . . . . . .355
9.5.2 Weighted Rule Evaluation (REVW) . . . . . . . . . . . . . . . . . . . . . . . . . .359
9.5.2.1 Set Up Prior to Executing REVW. . . . . . . . . . . . . . . . . . . . . . . . . .359
9.5.2.2 Interrupt Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .361
9.5.2.3 Cycle-by-Cycle Details for REVW . . . . . . . . . . . . . . . . . . . . . . . . .361
9.6 WAV Instruction Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .364
9.6.1 Set Up Prior to Executing WAV . . . . . . . . . . . . . . . . . . . . . . . . . . . . .364
9.6.2 WAV Interrupt Details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .365
9.6.3 Cycle-by-Cycle Details for WAV and wavr . . . . . . . . . . . . . . . . . . . . .365
9.7 Custom Fuzzy Logic Programming. . . . . . . . . . . . . . . . . . . . . . . . . . . . .369
9.7.1 Fuzzification Variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .369
9.7.2 Rule Evaluation Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .372
9.7.3 Defuzzification Variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .373
Appendix A. Instruction Reference
A.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .375
A.2 Stack and Memory Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .376
A.3 Interrupt Vector Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .376
A.4 Notation Used in Instruction Set Summary. . . . . . . . . . . . . . . . . . . . . . .377
A.5 Hexadecimal to Decimal Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . .402

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A.6 Decimal to Hexadecimal Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . .402
Appendix B. M68HC11 to CPU12 Upgrade Path
B.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .403
B.2 CPU12 Design Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .403
B.3 Source Code Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .404
B.4 Programmer’s Model and Stacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . .407
B.5 True 16-Bit Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .407
B.5.1 Bus Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .407
B.5.2 Instruction Queue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408
B.5.3 Stack Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .409
B.6 Improved Indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .410
B.6.1 Constant Offset Indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .412
B.6.2 Auto-Increment Indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .413
B.6.3 Accumulator Offset Indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
B.6.4 Indirect Indexing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .414
B.7 Improved Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415
B.7.1 Reduced Cycle Counts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415
B.7.2 Fast Math . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .415
B.7.3 Code Size Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .416
B.8 Additional Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417
B.8.1 Memory-to-Memory Moves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .420
B.8.2 Universal Transfer and Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . .420
B.8.3 Loop Construct. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .420
B.8.4 Long Branches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421
B.8.5 Minimum and Maximum Instructions . . . . . . . . . . . . . . . . . . . . . . . . .421
B.8.6 Fuzzy Logic Support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .422
B.8.7 Table Lookup and Interpolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .422
B.8.8 Extended Bit Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .423
B.8.9 Push and Pull D and CCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .423
B.8.10 Compare SP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .423
B.8.11 Support for Memory Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . .424
Appendix C. High-Level Language Support
C.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425
C.2 Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425

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C.3 Parameters and Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
C.3.1 Register Pushes and Pulls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426
C.3.2 Allocating and Deallocating Stack Space. . . . . . . . . . . . . . . . . . . . . .427
C.3.3 Frame Pointer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .427
C.4 Increment and Decrement Operators . . . . . . . . . . . . . . . . . . . . . . . . . . .428
C.5 Higher Math Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .428
C.6 Conditional If Constructs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .429
C.7 Case and Switch Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .429
C.8 Pointers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .429
C.9 Function Calls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .430
C.10 Instruction Set Orthogonality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .431

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1.1 Introduction
This manual describes the features and operation of the core (central
processing unit, or CPU, and development support functions) used in all
HCS12 microcontrollers. For reference, information is provided for the
M68HC12.
1.2 Features
The CPU12 is a high-speed, 16-bit processing unit that has a programming
model identical to that of the industry standard M68HC11 central processor
unit (CPU). The CPU12 instruction set is a proper superset of the M68HC11
instruction set, and M68HC11 source code is accepted by CPU12
assemblers with no changes.
•Full 16-bit data paths supports efficient arithmetic operation and
high-speed math execution
•Supports instructions with odd byte counts, including many
single-byte instructions. This allows much more efficient use of ROM
space.
•An instruction queue buffers program information so the CPU has
immediate access to at least three bytes of machine code at the start
of every instruction.
•Extensive set of indexed addressing capabilities, including:
– Using the stack pointer as an indexing register in all indexed
operations
– Using the program counter as an indexing register in all but auto
increment/decrement mode
– Accumulator offsets using A, B, or D accumulators
– Automatic index predecrement, preincrement, postdecrement,
and postincrement (by –8 to +8)
Reference Manual — S12CPUV2
Section 1. Introduction

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1.3 Symbols and Notation
The symbols and notation shown here are used throughout the manual.
More specialized notation that applies only to the instruction glossary or
instruction set summary are described at the beginning of those sections.
1.3.1 Abbreviations for System Resources
A — Accumulator A
B — Accumulator B
D — Double accumulator D (A : B)
X — Index register X
Y — Index register Y
SP — Stack pointer
PC — Program counter
CCR — Condition code register
S — STOP instruction control bit
X — Non-maskable interrupt control bit
H — Half-carry status bit
I — Maskable interrupt control bit
N — Negative status bit
Z — Zero status bit
V — Two’s complement overflow status bit
C — Carry/Borrow status bit

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1.3.2 Memory and Addressing
M — 8-bit memory location pointed to by the effective
address of the instruction
M : M+1 — 16-bit memory location. Consists of the contents of the
location pointed to by the effective address
concatenated with the contents of the location at the
nexthighermemoryaddress.Themostsignificantbyte
is at location M.
M~M+3
M(Y)~M(Y+3) — 32-bit memory location. Consists of the contents of the
effective address of the instruction concatenated with
thecontentsof the nextthreehighermemory locations.
The most significant byte is at location M or M(Y).
M(X) — Memory locations pointed to by index register X
M(SP) — Memory locations pointed to by the stack pointer
M(Y+3) — Memory locations pointed to by index register Y plus 3
PPAGE — Program overlay page (bank) number for extended
memory (>64 Kbytes).
Page — Program overlay page
XH— High-order byte
XL— Low-order byte
( ) — Content of register or memory location
$ — Hexadecimal value
% — Binary value

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1.3.3 Operators
+—Addition
–—Subtraction
•—Logical AND
+—Logical OR (inclusive)
⊕—Logical exclusive OR
×—Multiplication
÷—Division
M—Negation. One’s complement (invert each bit of M)
:—Concatenate
Example: A : B means the 16-bit value formed by concatenat-
ing 8-bit accumulator A with 8-bit accumulator B.
A is in the high-order position.
⇒—Transfer
Example: (A) ⇒M means the content of accumulator A is
transferred to memory location M.
⇔—Exchange
Example: D ⇔X means exchange the contents of D with
those of X.

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1.3.4 Definitions
Logic level 1 is the voltage that corresponds to the true (1) state.
Logic level 0 is the voltage that corresponds to the false (0) state.
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.
Asserted means that a signal is in active logic state. An active low signal
changes from logic level 1 to logic level 0 when asserted, and an active
high signal changes from logic level 0 to logic level 1.
Negated means that an asserted signal changes logic state. An active low
signal changes from logic level 0 to logic level 1 when negated, and an
active high signal changes from logic level 1 to logic level 0.
ADDR is the mnemonic for address bus.
DATA is the mnemonic for data bus.
LSB means least significant bit or bits.
MSB means most significant bit or bits.
LSW means least significant word or words.
MSW means most significant word or words.
A specific bit location within a range is referred to by mnemonic and
number. For example, A7 is bit 7 of accumulator A.
A range of bit locations is referred to by mnemonic and the numbers that
definetherange.Forexample,DATA[15:8]formthehighbyteofthedata
bus.

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