MSP430Microcontroller BasicsMSP430Microcontroller Basics John H.DaviesAMSTERDAM•BOSTON•HEIDELBERG•LONDONNEW YORK•OXFORD•PARIS•SAN DIEGOSAN FRANCISCO•SINGAPORE•SYDNEY•TOKYONewnes is an imprint of ElsevierNewnes is an imprint of Elsevier30Corporate Drive,Suite400,Burlington,MA01803,USALinacre House,Jordan Hill,Oxford OX28DP,UKCopyright©2008,Elsevier Ltd.All rights reserved.No part of this publication may be reproduced,stored in a retrieval system,or transmitted in any formor 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)1865843830,fax:(+44)1865853333,E-mail:************************.You may also complete your request online via the Elsevier homepage()by selecting “Support&Contact”then“Copyright and Permission”and then“Obtaining Permissions.”Recognizing the importance of preserving what has been written,Elsevier prints itsbooks on acid-free paper whenever possible.Library of Congress Cataloging-in-Publication DataApplication submittedBritish Library Cataloguing-in-Publication DataA catalogue record for this book is available from the British Library.ISBN:978-0-7506-8276-3For information on all Newnes publications,visit our Web site at:08091011121310987654321Printed in the United States of America“To Elizabeth.”ContentsPreface (xi)Chapter1:Embedded Electronic Systems and Microcontrollers (1)1.1What(and Where)Are Embedded Systems? (1)1.2Approaches to Embedded Systems (2)1.3Small Microcontrollers (5)1.4Anatomy of a Typical Small Microcontroller (8)1.5Memory (11)1.6Software (15)1.7Where Does the MSP430Fit? (16)Chapter2:The Texas Instruments MSP430 (21)2.1The Outside View—Pin-Out (21)2.2The Inside View—Functional Block Diagram (24)2.3Memory (25)2.4Central Processing Unit (30)2.5Memory-Mapped Input and Output (32)2.6Clock Generator (33)2.7Exceptions:Interrupts and Resets (36)2.8Where to Find Further Information (37)Chapter3:Development (43)3.1Development Environment (44)3.2The C Programming Language (46)3.3Assembly Language (55)3.4Access to the Microcontroller for Programming and Debugging (57)3.5Demonstration Boards (59)3.6Hardware (64)3.7Equipment (65)viii ContentsChapter4:A Simple Tour of the MSP430 (67)4.1First Program on a Conventional Desktop Computer (68)4.2Light LEDs in C (70)4.3Light LEDs in Assembly Language (72)4.4Read Input from a Switch (80)4.5Automatic Control:Flashing Light by Software Delay (91)4.6Automatic Control:Use of Subroutines (99)4.7Automatic Control:Flashing Light by Polling Timer_A (105)4.8Header Files and Issues Brushed under the Carpet (114)Chapter5:Architecture of the MSP430Processor (119)5.1Central Processing Unit (119)5.2Addressing Modes (125)5.3Constant Generator and Emulated Instructions (131)5.4Instruction Set (132)5.5Examples (146)5.6Reflections on the CPU and Instruction Set (153)5.7Resets (157)5.8Clock System (163)Chapter6:Functions,Interrupts,and Low-Power Modes (177)6.1Functions and Subroutines (178)6.2What Happens when a Subroutine Is Called? (178)6.3Storage for Local Variables (179)6.4Passing Parameters to a Subroutine and Returning a Result (183)6.5Mixing C and Assembly Language (185)6.6Interrupts (186)6.7What Happens when an Interrupt Is Requested? (188)6.8Interrupt Service Routines (190)6.9Issues Associated with Interrupts (196)6.10Low-Power Modes of Operation (198)Chapter7:Digital Input,Output,and Displays (207)7.1Digital Input and Output:Parallel Ports (208)7.2Digital Inputs (216)7.3Switch Debounce (225)7.4Digital Outputs (238)7.5Interface between3V and5V Systems (243)7.6Driving Heavier Loads (247)7.7Liquid Crystal Displays (252)7.8Driving an LCD from an MSP430x4xx (256)7.9Simple Applications of the LCD (264)Contents ix Chapter8:Timers (275)8.1Watchdog Timer (276)8.2Basic Timer1 (281)8.3Timer_A (287)8.4Measurement in the Capture Mode (300)8.5Output in the Continuous Mode (318)8.6Output in the Up Mode:Edge-Aligned Pulse-Width Modulation (330)8.7Output in the Up/Down Mode:Centered Pulse-Width Modulation (349)8.8Operation of Timer_A in the Sampling Mode (352)8.9Timer_B (353)8.10What Timer Where? (356)8.11Setting the Real-Time Clock:State Machines (357)Chapter9:Mixed-Signal Systems:Analog Input and Output (369)9.1Comparator_A (371)9.2Analog-to-Digital Conversion:General Issues (393)9.3Analog-to-Digital Conversion:Successive Approximation (402)9.4The ADC10Successive-Approximation ADC (407)9.5Basic Operation of the ADC10 (412)9.6More Advanced Operation of the ADC10 (424)9.7The ADC12Successive-Approximation ADC (432)9.8Analog-to-Digital Conversion:Sigma–Delta (438)9.9The SD16_A Sigma–Delta ADC (446)9.10Operation of SD16_A (459)9.11Signal Conditioning and Operational Amplifiers (475)9.12Digital-to-Analog Conversion (485)Chapter10:Communication (493)10.1Communication Peripherals in the MSP430 (495)10.2Serial Peripheral Interface (497)10.3SPI with the USI (504)10.4SPI with the USCI (513)10.5A Thermometer Using SPI in Mode3with the F2013as Master (520)10.6A Thermometer Using SPI in Mode0with the FG4618as Master (526)10.7Inter-integrated Circuit Bus (534)10.8A Simple I²C Master with the USCI_B0on a FG4618 (542)10.9A Simple I²C Slave with the USI on a F2013 (549)10.10State Machines for I²C Communication (559)10.11A Thermometer Using I²C with the F2013as Master (567)10.12Asynchronous Serial Communication (574)10.13Asynchronous Communication with the USCI_A (581)x Contents10.14A Software UART Using Timer_A (590)10.15Other Types of Communication (599)Chapter11:The Future:MSP430X (601)11.1Architecture of the MSP430X (601)11.2Instruction Set of the MSP430X (607)11.3Where Next? (614)11.4Conclusion (617)Appendix A:Kickstarting the MSP430 (619)A.1Introduction to EW430 (619)A.2Developing a Project in C (621)A.3Debugging with the Simulator (627)A.4Debugging with the Emulator (630)A.5Developing a Project in Assembly Language (633)A.6Tips for Using EW430 (636)A.7Tips for Specific Development Kits (640)Appendix B:Further Reading (645)Books and Articles (645)Newsletters,Magazines,and Journals (651)Index (655)Preface About a decade ago,I took over the teaching of afirst-year,second-semester course on digital electronics.It coveredflip-flops,counters,and state machines,all built fromsmall-scale integrated circuits.One of the projects at the end was to build a digital die.In many ways it was an excellent exercise because there were so many feasible ways in which it could be approached—simple counters,Johnson counters,or state machines.My concern was that it was very close to the project that I had experienced in myfirst course on digital electronics,which was back in the mid-1970s.The technology was close to the state of the art then,but was it still appropriate after so many years?Another feature of our course is that it is taken not only by electronic engineers but also by students from the science faculty,mostly computer scientists.I wanted these students to leave with a feeling for what can readily be done with modern programmable electronics insmaller-scale systems.I therefore replaced the material in the second half of the course with microcontrollers.(Do not worry,state machines were not abandoned—they are taught with hardware description languages in the context of programmable logic devices.) More recently,I thought that the time had come to review the choice of microcontroller. We traditionally used8-bit processors because modern devices have versatile peripherals and sophisticated embedded emulation and are quite powerful enough for most applications.Then the Texas Instruments MSP430caught my eye.A problem with8-bit microcontrollers is that8bits are too few for addresses,which are typically16bits long, and this means that data and addresses cannot be treated on an equal footing.In contrast, the MSP430has a uniform,16-bit architecture throughout:The address bus,data bus,and registers in the CPU are all16bits wide.The CPU has a modern design with plenty of registers,most of which can be used equally for data or addresses.It has a small instruction set with orthogonal addressing and an ingenious constant generator,which is used to emulate many operations that would otherwise need their own,distinct instructions.In many ways these features make the16-bit MSP430simpler than a typical8-bit processor.xii PrefaceOf course an elegant architecture does not generate many sales in the real world.More important are the range of peripherals and development tools.The MSP430offers the usual selection of peripherals plus some less common modules,including sigma–delta analog-to-digital converters and operational amplifiers.Some devices include hardware multipliers and digital-to-analog converters,which provide a complete signal chain(although,of course,Texas Instruments also offers an enormous range of digital signal processors).There is a choice of two free development environments(always an important considerationin education).One is IAR Embedded Workbench,which is available for a wide range of microcontrollers.Another,Code Composer Essentials,is produced by Texas Instruments itself.A third option is the GCC toolchain for MSP430at .I have not yet mentioned the major selling point of the MSP430,which is its low power consumption.Many microcontrollers are based on long-established designs withlow-power modes grafted onto them.This means that returning to full power from alow-power mode is often awkward and in some cases is virtually a reset operation.The MSP430is refreshingly different because it was designed from the outset for low-power operation.Entry to low-power modes and exit from them is straightforward,supported by a versatile clock system.For example,the clock module includes a digitally controlled oscillator that restarts at full speed from a low-power mode in less than1s in newer devices.In many applications the MSP430is put into a low-power mode,from which it is awakened by interrupts.These automatically restore full power for the interrupt service routine and return the processor to low power when it hasfinished.No extra code is needed for this:It is an intrinsic part of the interrupt mechanism.Most peripherals are designed for low power,although this can sometimes make them a little more complicated than would otherwise be necessary.The main point is that low-power modes are easy to use.The quality of the data sheets and user’s guides is another issue in education and those for the MSP430arefine.Unfortunately one item was missing in the area of documentation:a suitable textbook in English.I wrote this book tofill the gap.OutlineMost textbooks on microcontrollers follow one of two approaches.Thefirst is to present a sequence of projects to explore successive aspects of the device.I think that this works well for simpler architectures,notably the8-bit PICs,because it enables the reader to write functioning programs rapidly.This always feels good.Unfortunately I am not sure that it works as well for more advanced peripherals,which need considerable explanation before the reader can learn to use them fully.Preface xiii The alternative approach is to describe each module in the microcontroller fully and in turn,starting with the CPU and instruction set and working out to the peripherals.This makes for a well-organized reference book but can be tedious as a textbook.I tried to steer a course between these two.My inspiration is Kernighan and Ritchie’s The C Programming Language,which starts with a“Tutorial Introduction”before exploring the language systematically in subsequent chapters.I think that it takes rather more introduction to a microcontroller so the“simple tour,”which is my equivalent to the tutorial,does not start until Chapter4.Before that,thefirst chapter contains a general introduction to embedded systems and microcontrollers.This sets the scene for Chapter2, which focuses on the MSP430and gives a broad view of its features.I include a chapter on hardware and software for developing applications,which I hope will be particularly useful for readers who are new to microcontrollers.It also contains some reminders of features of the C language that are more prominent in programs for microcontrollers than desktop computers—bitfields for instance.This leads into the tour,which runs through some simple programs to illustrate input and output,the inevitableflashing LEDs,and an introduction to one of the timers(the MSP430has several).The remainder of the book provides a more systematic description of the MSP430.I start with the CPU and instruction set,and show how the constant generator is used to provide further“emulated”instructions.The clock system is also described in this chapter.It is followed by Chapter6on subroutines,interrupts,and low-power modes.I already mentioned that a major feature of the MSP430is the way in which low-power modes are handled automatically when interrupts are serviced.Subsequent chapters are concerned with the most widely used peripherals.Chapter7on digital input and output starts with the usual parallel ports and goes on to describe liquid crystal displays,which many MSP430s can drive directly.There is a wide selection of timers in the MSP430,which are covered in the next chapter.This is followed by a lengthy chapter on analog input and output.The MSP430offers many peripherals for analog-to-digital conversion,ranging from a simple comparator to a16-bit sigma–delta module.I do not think that you can use any of these without some understanding of their characteristics,which explains the length of this chapter.Some MSP430s include operational amplifiers and digital-to-analog converters,which I described briefly.Thefinal long chapter is on communication.I cover only three types of communication—serial peripheral interface,inter-integrated circuit bus,and asynchronous—but there are several peripherals for these in different variants of the MSP430,so there is a lot to explain.xiv PrefaceThe very last chapter provides an introduction to the MSP430X,an extended architecture with a20-bit address bus that can handle1MB of memory.There is also an appendix to take the reader through the steps of editing,building,and debugging thefirst project, which can sometimes be a frustrating experience.Ifind it annoying when books contain large chunks copied directly from data sheets and have tried to avoid this.You cannot hope to program a microcontroller without the data sheet at your side.Having said that,I start by going through each bit of the registers that control the peripherals used for the early programs.The idea is to explain how a typical peripheral is configured.After that I become more selective and concentrate on the overall function of the peripheral ually I pick out a few details that I think need extra explanation but skip the more mundane aspects.They are in the example programs inany case.I include links to many of Texas Instruments’application notes because I can see no point in repeating material that has been thoroughly explained already.Ifind that many students are strangely reluctant to use this valuable resource.There are a few reminders about code examples for the same reason.C or Assembly Language?Most small microcontrollers are now programmed using the C language so the question might seem redundant.In fact often columns in newletters on embedded systems often carry articles with titles such as“Is Assembly Language Dead?”However,the answer seems to be clearly that assembly language is not dead for small microcontrollers,such as the MSP430.Most code is written in C but you may occasionally need to write a subroutine in assembly language to perform an operation that cannot be written out directly in C.Two examples are operations that require bitwise rotations rather than shifts and calculations that can be done more efficiently by exploiting special instructions of the CPU,such as binary-coded decimal arithmetic.Intrinsic functions often avoid the need for assembly language but not always.More important,assembly language is often needed for debugging and this is the most compelling reason for describing it in a textbook.Small microcontrollers typically spend much of their time interacting with hardware by manipulating the registers that control the peripherals.Debugging may require stepping through lines of assembly language to check each step.You have to look at the manual to check the details of each instruction,but it helps to have a general idea of how the assembly language works.Preface xv From a pedagogical point of view,assembly language is useful to illustrate the architecture of the processor.In fact the MSP430is simple enough that you can explore the thinking behind the design of the instruction set.Besides,assembly language can be fun(in small doses).My approach is to develop thefirst,simple programs in Chapter4using both C and assembly language to show the relation between them.However,C dominates by the end of the chapter.Assembly language makes a strong showing in the next two chapters,which cover architecture,subroutines,and interrupts,including a section on mixing C and assembly language.Almost all remaining programs are in C,with assembly language reappearing only briefly for a function to convert numbers to binary-coded decimal.The listings in the text are read directly from the programs that I tested.Companion Web SitePlease visit the companion Web site for this book at/companions/9780750682763and download the programs used as examples in the book.These programs were read into the text of the book from the workspaces that I used for testing,which means that the downloadedfiles should match the book perfectly.Links are also provided for data sheets,user’s guides,and development tools.Solutions to the odd-numbered examples are freely available on the companion Web site but the remaining solutions are offered only to instructors. AcknowledgmentsIt is a pleasure to thank numerous people who have helped me in various ways to write this book.Many are from Texas Instruments:Bonnie Baker,Jacob Borgeson,Andreas Dannenberg,Colin Garlick,Thomas Mitnacht,and Robert Owen.I am particularly grateful to Adrian Valenzuela for his comments on thefinal draft.Several engineers from other companies were kind enough to provide advice and assistance:Edward Gibbins and Steve Duckworth from IAR,Tom Baugh of SoftBaugh,Paul Curtis of Rowley Associates,David Dyer of Ericsson and Fernando Rodriguez while he was at Texas Instruments.Finally,I am grateful to colleagues and students at Glasgow University,from whom I have learnt an enormous amount over the years.I’d like to thank Fernando Rodriguez(not the same person who was at Texas Instruments)and David Muir in particular,with both of whom I have run a wide range of projects on embedded systems and microcontrollers—from tutor boxes withflip-flops to the electronic systems of a Formula Student racing car.John Davies,Milngavie。
MSP430单片机入门例程MSP430单片机是一款低功耗、高性能的16位单片机，广泛应用于各种嵌入式系统。
下面是一个简单的MSP430单片机入门例程，可以让大家初步了解MSP430单片机的基本使用方法。
所需材料：1、MSP430单片机开发板2、MSP430单片机编译器3、MSP430单片机调试器4、电脑和相关软件步骤：1、安装MSP430单片机编译器首先需要安装MSP430单片机的编译器，该编译器可以将C语言代码编译成MSP430单片机可以执行的机器码。
在安装编译器时，需要选择与您的单片机型号匹配的编译器。
2、编写程序下面是一个简单的MSP430单片机程序，可以让LED灯闪烁：c本文include <msp430.h>int main(void)本文P1DIR |= 0x01; //设置P1.0为输出while(1){P1OUT ^= 0x01; //反转P1.0的状态，LED闪烁__delay_cycles(); //延时一段时间，控制闪烁频率}本文上述程序中，首先定义了P1DIR寄存器，将P1.0设置为输出。
然后进入一个无限循环，在循环中反转P1.0的状态，使LED闪烁。
使用__delay_cycles()函数实现延时，控制LED闪烁频率。
3、编译程序使用MSP430单片机编译器将程序编译成机器码，生成可执行文件。
在编译时，需要注意选择正确的编译器选项和单片机型号。
4、调试程序使用MSP430单片机调试器将可执行文件下载到单片机中，并使用调试器进行调试。
在调试时，可以观察单片机的输出口状态和LED灯的闪烁情况，确保程序正常运行。
随着嵌入式系统的发展，MSP430单片机作为一种低功耗、高性能的微控制器，在各种应用领域中得到了广泛的应用。
为了更好地理解和应用MSP430单片机，我在学习过程中积累了一些经验，现在分享给大家。
MSP430单片机是一种超低功耗的微控制器，由德州仪器（Texas Instruments）推出。
第1章MSP430单片机入门第一例1.1单片机简介单片微型计算机简称单片机，是典型的嵌入式微控制器（MicroController Unit），常用缩写MCU表示单片机。
单片机是一种集成电路芯片，采用超大规模集成电路技术把具有数据处理能力的中央处理器CPU、随机存储器RAM、只读存储器ROM、多种I/O口和中断系统、定时器/计时器等功能（可能还包括显示驱动电路、脉宽调制电路、模拟多路转换器、A/D转换器等电路）集成到一块硅片上构成的一个小而完善的微型计算机系统。
单片机已广泛地应用于军事、工业、家用电器、智能玩具、便携式智能仪表和机器人制作等领域。
目前，常用的单片机有Intel8051系列单片机；C8051F系列单片机；ATMEL 公司的AVR系列单片机；TI公司的MSP430系列单片机；Motorola单片机；PIC 系列单片机；飞思卡尔系列单片机；STM32系列单片机；ARM系列嵌入式等等。
单片机种类繁多，不同的单片机有着不同的硬件特性和软件特征，产品设计时单片机的选型是一项重要工作。
对于初学者来说千万不要贪多求全，最好的学习方法是选择一款单片机进行深入学习，学好这一款单片机后再触类旁通、举一反三选择最合适的单片机完成实际工程任务。
1.1.1超低功耗的MSP430单片机MSP430系列单片机是TI（Texas Instruments，美国德州仪器）公司近年来推出的一系列优秀的混合型微处理器产品。
MSP430单片机是一种基于RISC（精简指令集计算机）的16位混合信号处理器，专为满足超低功耗需求而精心设计，同时具备很好的数字/模拟信号处理能力，具有智能外设、易用性、低成本、业界最低功耗等优异特性，能满足仪器仪表、工业自动化、国防、家居智能化、医疗保健、智能农业等多方面的需求环境。
MSP430总体结构如图1.1所示，可分为八个部分：1）CPU：MSP430的CPU运行正交的精简指令集，采用16位的ALU（运算器）、指令控制逻辑和16个16位寄存器、27条内核指令及7种寻址模式。
