Some Assembly Required : Assembly Language Programming with the AVR Microcontroller

624 Pages·2012·5.322 MB·

by  Margush, Timothy S

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A family of internationally popular microcontrollers, the Atmel AVR

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for an educational environment. Until now, no text focused on the assembly lyE
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Some Assembly Required: Assembly Language Programming with the n
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AVR Microcontroller teaches the basic system capabilities of 8-bit AVR
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structures using AVR assembly language. It employs the core AVR 8-bit n P
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RISC microcontroller architecture and a limited collection of external r o
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devices, such as push buttons, LEDs, and serial communications, to g
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Each chapter contains numerous examples and exercises, including mR
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programming problems.
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• Presents a comprehensive treatment of assembly language
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programming and basic computer organization
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• Focuses on the popular Atmel AVR microcontroller series R
• Covers function call mechanisms and parameter passing techniques E
• Describes data representation for integers, floating point, and D
character data
• Explains how to use the XPLAIN Evaluation Kit
By studying assembly languages, computer scientists gain an understanding
of the functionality of basic processors and how their capabilities support
high level languages and applications. Exploring this connection between
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hardware and software, this book provides a foundation for understanding
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compilers, linkers, loaders, and operating systems in addition to the R
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processors themselves.
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SOME ASSEMBLY
REQUIRED
Assembly Language Programming
with the AVR Microcontroller

SOME ASSEMBLY
REQUIRED
Assembly Language Programming
with the AVR Microcontroller
TIMOTHY S. MARGUSH
CRC Press
Taylor & Francis Group
6000 Broken Sound Parkway NW, Suite 300
Boca Raton, FL 33487-2742
© 2012 by Taylor & Francis Group, LLC
CRC Press is an imprint of Taylor & Francis Group, an Informa business
No claim to original U.S. Government works
Version Date: 20110818
International Standard Book Number-13: 978-1-4398-9700-3 (eBook - PDF)
This book contains information obtained from authentic and highly regarded sources. Reasonable
efforts have been made to publish reliable data and information, but the author and publisher cannot
assume responsibility for the validity of all materials or the consequences of their use. The authors and
publishers have attempted to trace the copyright holders of all material reproduced in this publication
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Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced,
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Visit the Taylor & Francis Web site at
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My husband, Tim, died before completing the dedication page
so I am writing this for him. To Michael Decker who put in
hours of time proofreading text and code during a very busy
time in his life. He is a credit to his profession and a blessing to
our family. I would also like to dedicate this book to Tim's
brother, Philip Margush, whom Tim loved very much.
—Gail Margush

Contents
Acknowledgments, xxi
Author, xxiii
INTRODUCTION, XXV
Chapter 1 ◾ Computer Systems 1
BASIC PROCESSOR ARCHITECTURE 1
COMPONENTS OF A COMPUTER SYSTEM 2
Central Processing Unit 2
Storage 3
Input and Output 4
CLASSIFICATION OF PROCESSORS 5
CISC versus RISC 5
Functionality 5
Architecture 7
NUMERATION SYSTEMS 7
The Nature of Data 8
Binary, Octal, Hexadecimal, Decimal ... 10
Conversions 12
Repeated Division Algorithm 14
Polynomial Evaluation Algorithm 14
Horner’s Algorithm 14
BOOLEAN DATA 16
Boolean Operations 17
vii
viii   ◾   Contents
Applications of Boolean Operations 18
Mask Out, Clear, Zero 20
Set and Union 20
Toggle 21
Shifting and Rotating Bits 22
EXERCISES 23
Chapter 2 ◾ The Atmel AVR Microcontroller Family 27
THE AVR CORE 27
Instructions 28
Registers 28
Clock 29
MACHINE LANGUAGE FOR THE AVR
MICROCONTROLLER 30
One Plus One Equals? 30
Load Immediate 31
Add 34
Expanding Opcodes 36
Execution Trace 37
Jump 39
AVR STUDIO 42
New Project 42
Editor 43
Assembling 43
Debugger 44
Mnemonics 48
AVR DEVELOPMENT PLATFORMS 50
STK-500 Development Kit 50
The ATAVRXPLAIN Demonstration Kit 52
INTRODUCTION TO AVR ASSEMBLY LANGUAGE 53
Assembly Language Source Files 53
Line Format 54
Additional Features 54
Contents   ◾   ix
SAMPLE AVR ASSEMBLY LANGUAGE PROGRAM 55
A Counting Program 56
Explanation of the Statements 57
Assembling the Program 58
Obtaining a Listing File 58
The Map File 59
Simulating Execution 59
Downloading to the AVR Processor 60
Adjusting the Clock Speed 64
EXERCISES 66
PROGRAMMING EXERCISES 68
ALTERNATE PROGRAMS FOR THE XPLAIN
DEMONSTRATION KIT 69
Program 2.2a: Counter 69
Chapter 3 ◾ Assembly Language 73
DIRECTIVES 75
The Assembler’s Location Counters 75
EXPRESSIONS 79
Symbols and Literals 80
DATA DEFINITION DIRECTIVES 82
Operators Used in Expressions 83
Functions Used in Expressions 86
INSTRUCTIONS 87
Zero-Operand Instructions 89
One-Operand Instructions 90
Two-Operand Instructions 90
THE TOGGLER PROGRAM: SAMPLE I/O 90
AVR Digital I/O Ports and STK-500/XPLAIN LEDs 92
AVR Digital I/O Ports and STK-500/XPLAIN Pushbuttons 94
The Toggler Program 95
EXERCISES 99