NXP 68HC705X32 Reference guide

M68HC05TB/D

Rev. 2.0

M68HC05 Family

Understanding Small Microcontrollers

C5H

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M68HC05 Family — Understanding Small Microcontrollers—Rev. 2.0

MOTOROLA Acknowledgment 3

Acknowledgment

JamesM.Sibigtroth,aprincipalmemberofthetechnicalstaff

atMotorola,isauthorofthistextbook.HeisbasedinAustin,

Texas.

The author wishes to acknowledge Gordon Doughman for

contributing the chapter entitledOn-Chip Peripheral

Systems.GordonisafieldapplicationsengineerforMotorola

in Dayton, Ohio.

Motorola reserves the right to make changes without further notice to

any products herein to improve reliability, function or design. Motorola

does not assume any liability arising out of the application or use of any

product or circuit described herein; neither does it convey any license

under its patent rights nor the rights of others. Motorola products are not

designed, intended, or authorized for use as components in systems

intendedforsurgicalimplant intothe body,or otherapplications intended

to support or sustain life, or for any other application in which the failure

of the Motorola product could create a situation where personal injury or

death may occur. Should Buyer purchase or use Motorola products for

any such unintended or unauthorized application, Buyer shall indemnify

and hold Motorola and its officers, employees, subsidiaries, affiliates,

and distributors harmless against all claims, costs, damages, and

expenses, and reasonable attorney fees arising out of, directly or

indirectly, any claim of personal injury or death associated with such

unintended orunauthorized use,even if suchclaim alleges thatMotorola

was negligent regarding the design or manufacture of the part.

Motorola and the Motorola logo are registered trademarks of Motorola, Inc.

IBM is a registered trademark of IBM Corporation

Macintosh is a trademark of Apple Computer, Inc.

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Acknowledgment

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

4 Acknowledgment MOTOROLA

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M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA List of Sections 5

List of Sections

Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

What is a Microcontroller? . . . . . . . . . . . . . . . . . . . . . . . 17

Computer Numbers and Codes . . . . . . . . . . . . . . . . . . 27

Basic Logic Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Computer Memory and Parallel I/O . . . . . . . . . . . . . . . 51

Computer Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 65

M68HC05 Instruction Set . . . . . . . . . . . . . . . . . . . . . . . . 97

Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

The Paced Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

On-Chip Peripheral Systems . . . . . . . . . . . . . . . . . . . . 179

Instruction Set Details . . . . . . . . . . . . . . . . . . . . . . . . . . 217

Reference Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

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List of Sections

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

6 List of Sections MOTOROLA

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M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA Table of Contents 7

Table of Contents

What is a Microcontroller?

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Overall View of a Computer System . . . . . . . . . . . . . . . . . . . . . . . . . .18

Computer System Inputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Computer System Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Central Processor Unit (CPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Computer Memory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Computer Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

The Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

The Parts of Any Computer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Kinds of Computers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Computer Numbers and Codes

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Binary and Hexadecimal Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . .28

ASCII Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Computer Operation Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Instruction Mnemonics and Assemblers . . . . . . . . . . . . . . . . . . . . . . .32

Octal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Binary Coded Decimal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

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Table of Contents

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

8 Table of Contents MOTOROLA

Basic Logic Elements

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

Logic Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

CMOS Transistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Simple Gates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Inverter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

NAND Gate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

NOR Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Transmission Gates, Buffers, and Flip Flops. . . . . . . . . . . . . . . . . . . .44

Transmission Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Three-State Buffer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Half Flip Flop (HFF). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Computer Memory and Parallel I/O

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Pigeon Hole Analogy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

How a Computer Sees Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Kilobytes, Megabytes, and Gigabytes. . . . . . . . . . . . . . . . . . . . . . . . .54

Kinds of Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

Random Access Memory (RAM). . . . . . . . . . . . . . . . . . . . . . . . . . .55

Read-Only Memory (ROM). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Programmable ROM (PROM). . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

EPROM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

OTP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

EEPROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

I/O as a Memory Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

Internal Status and Control Registers. . . . . . . . . . . . . . . . . . . . . . .59

Memory Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

Memory Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

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Table of Contents

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA Table of Contents 9

Computer Architecture

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Computer Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

CPU Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

CPU View of a Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

CPU Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Detailed Operation of CPU Instructions . . . . . . . . . . . . . . . . . . . . .73

Store Accumulator (Direct Addressing Mode). . . . . . . . . . . . . . .74

Load Accumulator (Immediate Addressing Mode) . . . . . . . . . . .75

Conditional Branch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

Subroutine Calls and Returns. . . . . . . . . . . . . . . . . . . . . . . . . . .76

Playing Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

Resets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

RESET Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Watchdog Timer Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

External Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91

On-Chip Peripheral Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

Software Interrupt (SWI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

Interrupt Latency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

Nested Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94

M68HC05 Instruction Set

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Central Processor Unit (CPU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Arithmetic/Logic Unit (ALU). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

CPU Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Index Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

Condition Code Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

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Table of Contents

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

10 Table of Contents MOTOROLA

Half-Carry Bit (H) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Interrupt Mask Bit (I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Negative Bit (N). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Zero Bit (Z) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102

Carry/Borrow Bit (C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102

Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

Addressing Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104

Inherent Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

Immediate Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

Extended Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108

Direct Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110

Indexed Addressing Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Indexed, No Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112

Indexed, 8-Bit Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114

Indexed, 16-Bit Offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116

Relative Addressing Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118

Bit Test and Branch Instructions. . . . . . . . . . . . . . . . . . . . . . . . . .120

Instructions Organized by Type . . . . . . . . . . . . . . . . . . . . . . . . . .120

Instruction Set Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .125

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

Addressing Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133

Instruction Execution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134

Programming

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .135

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136

Writing a Simple Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136

Flowchart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137

Mnemonic Source Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139

Software Delay Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141

Assembler Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143

Object Code File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147

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M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA Table of Contents 11

Assembler Directives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149

Originate (ORG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149

Equate (EQU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149

Form Constant Byte (FCB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150

Form Double Byte (FDB). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150

Reserve Memory Byte (RMB). . . . . . . . . . . . . . . . . . . . . . . . . . . .151

Set Default Number Base to Decimal . . . . . . . . . . . . . . . . . . . . . .152

Instruction Set Dexterity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153

Application Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156

The Paced Loop

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159

System Equates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160

Register

Equates for MC68HC705J1A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160

Application System Equates . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161

Vector Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162

Reset Vector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162

Unused Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163

RAM Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

Paced Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

Loop Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .167

Loop System Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168

Your Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .168

Timing Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169

Stack Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .170

An Application-Ready Framework. . . . . . . . . . . . . . . . . . . . . . . . . . .171

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178

On-Chip Peripheral Systems

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180

Types of Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181

Timers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181

Serial Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182

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Table of Contents

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

12 Table of Contents MOTOROLA

Analog-to-Digital Converters. . . . . . . . . . . . . . . . . . . . . . . . . . . . .183

Digital-to-Analog Converters. . . . . . . . . . . . . . . . . . . . . . . . . . . . .183

EEPROM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183

Controlling Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183

The MC68HC705J1A Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184

A Timer Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187

Using the PWM Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195

A Practical Motor Control Example . . . . . . . . . . . . . . . . . . . . . . . . . .198

Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198

Motor Control Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201

Motor Control Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .204

Listing 6 — Speed Control Program Listing . . . . . . . . . . . . . . . . .210

Review. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215

Other Kinds of Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215

Instruction Set Details

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .217

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219

M68HC05 Instruction Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221

Reference Tables

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .287

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .287

ASCII to Hexadecimal Conversion . . . . . . . . . . . . . . . . . . . . . . . . . .288

Hexadecimal to Decimal Conversion. . . . . . . . . . . . . . . . . . . . . . . . .290

Decimal to Hexadecimal Conversion. . . . . . . . . . . . . . . . . . . . . . . . .292

Hexadecimal Values vs. M68HC05 Instructions . . . . . . . . . . . . . . . .293

Glossary

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299

Index

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317

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M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA List of Figures 13

List of Figures

Figure Title Page

1 Overall View of a Computer System . . . . . . . . . . . . . . . . . .18

2 Expanded View of a Microcontroller. . . . . . . . . . . . . . . . . . .24

3 N-Type and P-Type CMOS Transistors . . . . . . . . . . . . . . . .39

4 CMOS Inverter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

5 CMOS NAND Gate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

6 CMOS NOR Gate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

7 CMOS Transmission Gate . . . . . . . . . . . . . . . . . . . . . . . . . .44

8 2:1 Data Multiplexer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

9 Three-State Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

10 Half Flip Flop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

11 Memory and I/O Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . .58

12 I/O Port with Data Direction Control. . . . . . . . . . . . . . . . . . .59

13 Expanded Detail of One Memory Location. . . . . . . . . . . . . .60

14 Typical Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

15 M68HC05 CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . .68

16 Memory Map of Example Program. . . . . . . . . . . . . . . . . . . .72

17 Subroutine Call Sequence . . . . . . . . . . . . . . . . . . . . . . . . . .77

18 Worksheet for Playing Computer . . . . . . . . . . . . . . . . . . . . .81

19 Completed Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82

20 Hardware Interrupt Flowchart. . . . . . . . . . . . . . . . . . . . . . . .90

21 Interrupt Stacking Order. . . . . . . . . . . . . . . . . . . . . . . . . . . .91

22 M68HC05 CPU Block Diagram . . . . . . . . . . . . . . . . . . . . . .98

23 Programming Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

24 Accumulator (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

25 Index Register (X) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100

26 Condition Code Register (CCR). . . . . . . . . . . . . . . . . . . . .101

27 How Condition Codes are Affected

by Arithmetic Operations. . . . . . . . . . . . . . . . . . . . . . . .102

28 Program Counter (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

29 Stack Pointer (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

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List of Figures

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

14 List of Figures MOTOROLA

Figure Title Page

30 Example Flowchart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138

31 Flowchart and Mnemonics . . . . . . . . . . . . . . . . . . . . . . . . .140

32 Delay Routine Flowchart and Mnemonics . . . . . . . . . . . . .141

33 Explanation of Assembler Listing. . . . . . . . . . . . . . . . . . . .145

34 Syntax of an S1 Record . . . . . . . . . . . . . . . . . . . . . . . . . . .148

35 S-Record File for Example Program . . . . . . . . . . . . . . . . .148

36 Four Ways to Check a Switch . . . . . . . . . . . . . . . . . . . . . .153

37 Flowchart of Main Paced Loop. . . . . . . . . . . . . . . . . . . . . .166

38 Flowchart of RTI Service Routine. . . . . . . . . . . . . . . . . . . .167

39 15-Stage Multifunction Timer Block Diagram. . . . . . . . . . .185

40 PWM Waveforms with Various Duty Cycles. . . . . . . . . . . .187

41 Portion of the MC68HC705J1A Timer . . . . . . . . . . . . . . . .188

42 PWM With 16 Discrete Duty Cycle Outputs . . . . . . . . . . . .189

43 Each TOF Interrupt Sliced into 16 Separate

Time Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191

44 Timer Interrupt Service Routine . . . . . . . . . . . . . . . . . . . . .192

45 Real-Time Interrupt Routine Flowchart . . . . . . . . . . . . . . .193

46 Timer Overflow Interrupt Flowchart . . . . . . . . . . . . . . . . . .194

47 Motor Speed Controlled by a Variable Resistor. . . . . . . . .199

48 Motor Speed Controlled by a Transistor. . . . . . . . . . . . . . .199

49 Transistor Used as an Electronic Switch . . . . . . . . . . . . . .200

50 PWM Waveforms with 50 and 80 Percent

Duty Cycles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201

51 Power Section of the Motor Speed Control Circuit. . . . . . .203

52 Microcontroller Section of the Motor

Speed Control Circuit . . . . . . . . . . . . . . . . . . . . . . . . . .203

53 Revised RTI Routine Flowchar. . . . . . . . . . . . . . . . . . . . . .205

54 Flowchart for Main Program Loop . . . . . . . . . . . . . . . . . . .206

55 Flowchart for MotorOn/Off Routine . . . . . . . . . . . . . . . . . .208

56 Flowchart for Motor Speed-Up Routine . . . . . . . . . . . . . . .209

57 Flowchart for Motor Speed-Down Routine . . . . . . . . . . . . .209

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M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA List of Tables 15

List of Tables

Table Title Page

1 Decimal, Binary, and Hexadecimal Equivalents.....................29

2 ASCII to Hexadecimal Conversion ........................................31

3 Octal, Binary, and Hexadecimal Equivalents..........................33

4 Decimal, BCD, and Binary Equivalents..................................35

5 Inverter Gate Operation..........................................................40

6 NAND Gate-Level Operation..................................................41

7 NOR Gate Truth Table ...........................................................43

8 Data Multiplexer Operation.....................................................46

9 Buffer Gate Operation ............................................................47

10 Vector Addresses for Resets and Interrupts

on the MC68HC705J1A.....................................................89

11 Register/Memory Instructions...............................................121

12 Read/Modify-Write Instructions ............................................122

13 Branch Instructions...............................................................123

14 Control Instructions...............................................................124

15 Instruction Set Summary......................................................126

16 M68HC05 Instruction Set Opcode Map................................132

17 RTI and COP Timer Rates (E clock = 2 MHz)......................186

18 PWM Characteristics for Various RTI Rates ........................190

19 Hexadecimal to ASCII Conversion ......................................289

20 Hexadecimal to Decimal Conversion....................................291

21 Hexadecimal to M68HC05 Instruction Mnemonics...............293

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List of Tables

M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

16 List of Tables MOTOROLA

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M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0

MOTOROLA What is a Microcontroller? 17

What is a Microcontroller?

Contents