Kirk Zurell - C Programming for Embedded Systems

TEAMFLY Team-Fly Page i C Programming for Embedded Systems Kirk Zurell Page ii Disclaimer: This netLibrary eBook does not include the ancillary media that was packaged with the original printed version of the book. R&D BooksCMP Media, Inc.1601 W. 23rd Street, Suite 200Lawrence, KS 66046USA Designations used by companies to distinguish their products are often claimed as trademarks. In all instances where R&D is aware of a trademark claim, the product name appears in initial capital letters, in all capital letters, or in accordance with the vendor's capitalization preference. Readers should contact the appropriate companies for more complete information on trademarks and trademark registrations. All trademarks and registered trademarks in this book are the property of their respective holders.

Copyright 2000 by Byte Craft Limited. Licensed Material. All rights reserved. Published by R&D Books, CMP Media, Inc. All rights reserved. Printed in the United States of America.

No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher; with the exception that the program listings may be entered, stored, and executed in a computer system, but they may not be reproduced for publication. The programs in this book are presented for instructional value. The programs have been carefully tested, but are not guaranteed for any particular purpose. The publisher does not offer any warranties and does not guarantee the accuracy, adequacy, or completeness of any information herein and is not responsible for any errors or omissions. The publisher assumes no liability for damages resulting from the use of the information in this book or for any infringement of the intellectual property rights of third parties that would result from the use of this information. Distributed in the U.S. and Canada by:Publishers Group West1700 Fourth StreetBerkeley, CA 94710ISBN 1-929629-04-4 Page iii BYTE CRAFT LIMITED421 King Street NorthWaterloo, OntarioCanada N2J 4E4Telephone: (519) 888-6911Fax: (519) 746-6751E-mail: info@bytecraft.com http://www.bytecraft.com All example and program code is protected by copyright. and Canada by: Publishers Group West1700 Fourth StreetBerkeley, CA 94710ISBN 1-929629-04-4 Page iii BYTE CRAFT LIMITED421 King Street NorthWaterloo, OntarioCanada N2J 4E4Telephone: (519) 888-6911Fax: (519) 746-6751E-mail: info@bytecraft.com http://www.bytecraft.com All example and program code is protected by copyright.

Intel is a registered trademark of Intel Corporation. Microsoft and Windows are trademarks or registered trademarks of Microsoft Corporation. PC is a registered trademark of International Business Machines Corporation. Motorola is a registered trademark of Motorola Inc. COP8, MICROWIRE, and MICROWIRE/PLUS are trademarks or registered trademarks of National Semiconductor Corporation. in the USA Scenix is a trademark of Scenix Semiconductor, Inc. in the USA Scenix is a trademark of Scenix Semiconductor, Inc.

Cypress is a trademark of Cypress Semiconductor Corporation. I2C is a registered trademark of Philips. All other trademarks mentioned herein are property of their respective companies. Page v Acknowledgments I would like to thank Walter Banks at Byte Craft Limited for dropping me head-first into the world of embedded programming. Walter and Andre have provided copious expertise in the very finest points of C programming and code generation. I would also like to thank my parents, who went out on a limb and purchased that Commodore 64 all those years ago.

I hereby disclose publicly that I did not wash the dishes forever, as promised. Page vii Table of Contents Acknowledgments v Chapter 1 Introduction Role of This Book Benefits of C in Embedded Systems Outline of the Book Typographical Conventions Updates and Supplementary Information Chapter 2 Problem Specification Product Requirements Hardware Engineering Software Planning Software Architecture Pseudocode Flowchart State Diagram Resource Management Testing Regime Page viii Chapter 3 Microcontrollers In-depth The Central Processing Unit (CPU) Instruction Sets The Stack Memory Addressing and Types RAM and ROM ROM and Programming von Neumann Versus Harvard Architectures Timers Watchdog Timer Examples 26 Interrupt Circuitry Vectored and Nonvectored Arbitration Saving State during Interrupts Executing Interrupt Handlers Multiple Interrupts RESET I/O Ports Analog-to-Digital Conversion Serial Peripheral Buses Development Tools for a Microcontroller Chapter 4 Design Process Product Functionality Hardware Design Software Design Software Architecture Flowchart Resource Management Scratch Pad Interrupt Planning Testing Choices Design for Debugging Code Inspection Execution within a Simulator Environment Execution within an Emulator Environment Target System in a Test Harness Page ix Chapter 5 C for Embedded Systems In-line Assembly Language Device Knowledge #pragma has #pragma port Endianness Mechanical Knowledge Libraries First Look at an Embedded C Program Chapter 6 Data Types and Variables Identifier Declaration Special Data Types and Data Access Function Data Types The Character Data Type Integer Data Types Byte Craft's Sized Integers Bit Data Types Real Numbers Complex Data Types Pointers Arrays Enumerated Types Structures Unions typedef Data Type Modifiers Value Constancy Modifiers: const and volatile Allowable Values Modifiers: signed and unsigned Size Modifiers: short and long Pointer Size Modifiers: near and far Storage Class Modifiers External Linkage Internal Linkage No Linkage The extern Modifier The static Modifier The register Modifier The auto Modifier Page x Chapter 7 C Statements, Structures, and Operations Combining Statements in a Block Functions Function Parameters Control Structures The main() Function Initialization Functions Control Statements Decision Structures Looping Structures Control Expression break and continue Operators and Expressions TEAMFLY Standard Math Operators Bit Logical Operators Bit Shift Operators Chapter 8 Libraries Creating Libraries Writing the Library Libraries and Linking Chapter 9 Optimizing and Testing Embedded C Programs Team-Fly Optimization Instruction Set-Dependent Optimizations Hand Optimization Manual Variable Tweaking Debugging Embedded C Register Type Modifier Local Memory Pointers Mixed C and Assembly Calling Conventions Access to C Variables from Assembly Exercising Hardware Debugging by Inspection Page xi Dummy Loads Working with Emulators and Simulators Simulators Emulators The Packaging of Embedded Software Chapter 10 Sample Project Hardware Exercise Programs "Hello World!" Keypad Test LCD Test Talking to Ports A/D Converter Theory Appendix A Table of Contents Appendix A Embedded C Libraries Appendix B ASCII Chart Appendix C Glossary Index What's on the CD-ROM? Page 1 Chapter 1Introduction1.1Role of This Book This book provides a complete intermediate-level discussion of microcontroller programming using the C programming language. It covers both the adaptations to C necessary for targeting an embedded environment, and the common components of a successful development project. C is the language of choice for programming larger microcontrollers (MCU), those based on 32-bit cores. These parts are often derived from their general-purpose counterparts, and are both as complex and feature-rich. As a result, C (and C++) compilers are necessary and readily available for these MCUs.