TEAM LRN Analog and Digital Circuits for Electronic Control System Applications TEAM LRN This page intentionally left blank TEAM LRN Analog and Digital Circuits for Electronic Control System Applications Using the TI MSP430 Microcontroller by Jerry Luecke AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Newnes is an imprint of Elsevier TEAM LRN Newnes is an imprint of Elsevier 200 Wheeler Road, Burlington, MA 01803, USA Linacre House, Jordan Hill, Oxford OX2 8DP, UK Copyright © 2005, Elsevier Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone: (+44) 1865 843830, fax: (+44) 1865 853333, e-mail: permissions@elsevier.com.uk. You may also complete your request on-line via the Elsevier homepage (http://elsevier.com), by selecting “Customer Support” and then “Obtaining Permissions.” Recognizing the importance of preserving what has been written, Elsevier prints its books on acid-free paper whenever possible. Library of Congress Cataloging-in-Publication Data Luecke, Gerald. Analog and digital circuits for electronic control system applications : using the TI MSP430 microcontroller / by Gerald Luecke. p. cm. ISBN 0-7506-7810-0 1. Electronic circuit design. 2. Electronic control. 3. Programmable controllers. I. Title. TK7867.L84 2004 629.8'9 dc22 2004054669 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. For information on all Newnes publications visit our Web site at www.books.elsevier.com 04 05 06 07 08 09 10 9 8 7 6 5 4 3 2 1 Printed in the United States of America. TEAM LRN The book is dedicated to my wife Velma and our grandchildren: From the Luecke side: Cameron, Graham, Andy, Alex, Alyssa, Brent, Jacob, Harper, Arielle, Emery. From the Hubbard side: Jared, Garrett, Matthew, Ashton, Audrey. TEAM LRN This page intentionally left blank TEAM LRN vii Contents Foreword xi Preface xii Acknowledgments xiii What’s on the CD-ROM? xiv Chapter 1: Signal Paths from Analog to Digital 1 Introduction 1 A Refresher 1 Accuracy vs. Speed—Analog and Digital 5 Interface Electronics 6 The Basic Functions for Analog-to-Digital Conversion 6 Summary 8 Chapter 1 Quiz 9 Chapter 2: Signal Paths from Digital to Analog 11 Introduction 11 The Digital-to-Analog Portion 11 Filtering 13 Conditioning the Signal 13 Transducing the Signal 13 Summary 15 Chapter 2 Quiz 16 Chapter 3: Sensors 18 Introduction 18 Temperature Sensors 18 Angular and Linear Position 21 Rotation 24 Magnetoresistor Sensor 24 Pressure 25 Light Sensors 27 Other Sensors 32 Summary 32 Chapter 3 Quiz 32 Chapter 4: Signal Conditioning 35 Introduction 35 Amplification 35 Bipolar NPN Amplifier 36 Amplifier Frequency Response 39 Coupling 40 Small-Signal vs. Large Signal 41 Classes of Amplifiers 42 Field-Effect Transistor Amplifiers 42 A N-Channel JFET Amplifier Design 43 An NPN MOSFET Amplifier 45 TEAM LRN viii Contents Operational Amplifiers 47 Conditioning the Output of a Pressure Sensor 50 A More Sophisticated Pressure Sensor Amplifier 51 Current Mirror 52 Applications of Op Amps 53 Oscillators 53 Power Amplifiers 54 Class B Audio Power Amplifier 56 Special Signals 56 RC Time Constants 58 Frequency Selection 59 Typical Application of Filters 61 Summary 62 Chapter 4 Quiz 62 Chapter 5: Analog-to-Digital and Digital-to-Analog Conversions 66 Introduction 66 Decimal Equivalent of a Binary Number 67 Digital Codes of ADC 67 A Resistor Network DAC 68 A Simple Resistor-String DAC 71 A Simple Current-Steering DAC 72 Analog-to-Digital Converters (ADC) 73 Successive Approximation Register (SAR) ADC 74 Capacitor Charge-Redistribution ADC 75 Highest Speed Conversions 78 Sample and Hold and Filters 78 Summary 79 Chapter 5 Quiz 80 Chapter 6: Digital System Processing 82 Introduction 82 Digital Processor or Digital Computer 82 What is a Microprocessor? 86 What is a Microcomputer? 86 System Clarifications 86 Digital Signal Representations 90 Clock, Timing and Control Signals 90 Interrupts 92 Status Bits 92 More About Software 93 Sophisticated Programming Languages 95 How Parts of a Processor Perform Their Functions 95 Memory and Input/Output 97 Addressing Modes 97 Summary 99 Chapter 6 Quiz 100 Chapter 7: Examples of Assembly-Language Programming 103 Introduction 103 A Processor for the Examples 103 About the MSP430 Family 103 The CPU 104 TEAM LRN ix Contents Program Memory and Data Memory 105 Peripherals 106 Operation Control and Operating Modes 106 Watchdog Timer 106 System Reset 107 Interrupts 107 Oscillators and Clock Generators 107 Timers 109 Addressing Modes 109 More on MSP430 Control 110 Further Thoughts 114 Labels 117 Instructions 117 Operands 117 Hexadecimal Numbers 117 Comments 118 Programming Examples 118 Subprogram No. 1 118 Subprogram No. 2 127 Subprogram No. 3 131 Variation of Threshold 137 Summary 137 Chapter 7 Quiz 138 Chapter 8: Data Communications 142 Introduction 142 The Data Transmission System 142 Parallel and Serial Transmission 142 Protocols 144 High-Speed Data Transmissions 145 Serial Data Communications Advances 145 A Return to the Format 145 Shift Registers 147 USART Serial Communications 148 The UART Function with Software. 150 Technology Advances 150 I 2 C Protocol 150 USB 152 Summary 156 Chapter 8 Quiz 157 Chapter 9: System Power and Control 160 Introduction 160 Voltage Regulators 161 Load Variations 162 Actual Linear Voltage Regulator Circuit 163 Voltage Regulation 163 Power Dissipation 164 Switching Voltage Regulators 165 Summary of Regulators 167 Power Supply Distribution 168 Power System Supervisors 170 TEAM LRN [...]... world and back again and, in a similar fashion, from the analog systems to digital systems and back again Analog and Digital Circuits for Control System Applications identifies the electronic functions needed, and describes how electronic circuits are designed and applied to implement the functions, and gives examples of the use of the functions in systems A Refresher Since the book deals with the electronic. .. very high-speed IC digital processors available with their high accuracy; convert the digital signals back to analog signals; and output the analog signals to perform the task at hand Analog and Digital Circuits for Control System Applications: Using the TI MSP430 Microcontroller explains the functions that are in the signal chain, and explains how to design electronic circuits to perform the functions... functions and circuits that interface or couple analog- to -digital circuits and systems, or vice versa, a short review is provided so it is clearly understood what analog means and what digital means Analog Analog quantities vary continuously, and analog systems represent the analog information using electrical signals that vary smoothly and continuously over a range A good example of an analog system. .. from Analog to Digital Chapter 1 Quiz 1 2 3 4 5 6 7 8 A new design technique available to analog system designers is: a Sense the analog, compute using analog, output analog b Sense the analog, convert to digital, compute digitally, convert to analog, output analog c Sense the analog, convert to digital, compute digitally, output digitally d Sense digitally, compute digitally, output digitally Analog. .. sensors and their outputs There is a chapter on the different techniques of conditioning the sensor signals, especially amplifiers and op amps There are techniques and circuits for analog- to -digital and digital- to -analog conversions, and an explanation of what a digital processor is and how it works There is a chapter on data transmissions and one on power control And to solidify the learning and applications, ... signals to digital systems that perform calculations, manipulate, and process the digital signals and then return the signals to analog form This chapter deals with the analog- to -digital portion of Figure 1-7, and Chapter 2 will deal with the digital- to -analog portion The Basic Functions for Analog- to -Digital Conversion Sensing the Input Signal Figure 1-8 separates out the analog- to -digital portion of... input voltage and the voltage recorded at the next sample Example 4 A to D Conversion For the analog signal shown in the plot of voltage against time and the 4-bit codes given for the indicated analog voltages, identify the analog voltage values at the sample points and the resultant digital For the following signal shown and the code for analog codes and fill in theanalog the analog table 4-bitand the resultant... will not work Timing is maintained in digital systems by circuits called system clocks This is what identifies a digital signal and the information being processed in a digital system Binary The two levels—ON and OFF—are most commonly identified as 1(one) and zero (0) in modern binary digital systems, and the 1 and 0 are called binary digits or bits for short Since the system is binary (two levels), the... reviewed analog and digital signals and systems, digital codes, the decimal and binary number systems, and the basic functions required to convert analog signals to digital signals The next chapter will complete the look at the basic functions required to convert digital signals to analog signals It will be important to have these basic functions in mind as the electronic circuits that perform these... human world and the electronic world b the wholesale world and the retail world c the private business world and the government business world d the analog world and the digital world e a and d above f none of the above In analog electronic systems, analog quantities are: a not analogous to the original quantity b are not a copy of the original quantity in another form c are output in digital form d are . LRN Analog and Digital Circuits for Electronic Control System Applications TEAM LRN This page intentionally left blank TEAM LRN Analog and Digital Circuits for Electronic Control System Applications Using. world to the electronics world and back again and, in a similar fashion, from the analog systems to digital systems and back again. Analog and Digital Circuits for Control System Applications. back to analog signals; and output the analog signals to perform the task at hand. Analog and Digital Circuits for Control System Applications: Using the TI MSP430 Microcontroller explains the