毕业设计(论文)-多功能信号发生器的设计与实现

陕西理工学院毕业设计第第页 if(FreqNum[3]==-1) FreqNum[3]=9; LCDDispNum(6,2,FreqNum[3]);LCDDispNum(5,2,FreqNum[2]); } elseif(gFunctionCount==2&&gTimeCount==2) { FreqNum[2]--; if(FreqNum[2]==-1) FreqNum[2]=9; LCDDispNum(5,2,FreqNum[2]);LCDDispNum(4,2,FreqNum[1]); } elseif(gFunctionCount==2&&gTimeCount==3) { FreqNum[1]--; if(FreqNum[1]==-1) FreqNum[1]=9; LCDDispNum(4,2,FreqNum[1]);LCDDispNum(3,2,FreqNum[0]); } elseif(gFunctionCount==2&&gTimeCount==4) { FreqNum[0]--; if(FreqNum[0]==-1) FreqNum[0]=9; LCDDispNum(3,2,FreqNum[0]);LCDDispChar(2,2,''); } elseif(gFunctionCount==2&&gTimeCount==0) { FreqNum[4]--; if(FreqNum[4]==-1) FreqNum[4]=9; LCDDispNum(7,2,FreqNum[4]); LCDDispNum(6,2,FreqNum[3]); } elseif(gFunctionCount==3&&gTimeCount==0) { AmpNum[1]--; if(AmpNum[1]==-1) AmpNum[1]=9; LCDDispNum(14,1,AmpNum[1]); LCDDispChar(13,1,'.'); } elseif(gFunctionCount==3&&gTimeCount==1) { AmpNum[0]--; if(AmpNum[0]==-1) AmpNum[0]=5; LCDDispNum(12,1,AmpNum[0]); LCDDispChar(11,1,':'); } elseif(gFunctionCount==4&&gTimeCount==0) { DutyNum[1]--; if(DutyNum[1]==-1) DutyNum[1]=9; LCDDispNum(14,2,DutyNum[1]); LCDDispNum(13,2,DutyNum[0]); } elseif(gFunctionCount==4&&gTimeCount==1) { DutyNum[0]--; if(DutyNum[0]==-1) DutyNum[0]=9; LCDDispNum(13,2,DutyNum[0]); LCDDispChar(12,2,':'); } }while(!KEY4);//循环到松手 }}附录D英文原文1Introduction

SCMisanintegratedcircuitchip,VLSItechnologywithdataprocessingcapabilityofthecentralprocessingunitCPUrandomaccessmemoryRAM,readonlymemoryROM,andavarietyofI/Oportandinterruptsystem,timers/timerotherfunctions(whichmayalsoincludeadisplaydrivercircuit,pulsewidthmodulationcircuit,analogmulti-channelconverter,A/Dconverterandothercircuit)integratedintoasiliconconstituteasmallcomputersystem.

Thewaveformgeneratorisadatasignalgenerator,inthedebuggingofhardware,weoftenneedtoaddsomesignal,whetheritisnormaltoobservecircuitoperation.Generalsignalgenerator,notonlycumbersome,butonlymadeafewsimplewaveform,cannotmeettheneed.Example,whenuserswanttodebugserialcommunicationprogram,itisnecessaryonthecomputertowriteaprogram,andthenwiretoconnectthecomputerandtheusertargetboard,ifnotnormal,donotknowthatthecommunicationlineshaveaproblemoraproblemwiththeprogram.E2000/Lwaveformgeneratorcapability,youcandefinetheserialdata.Outputlogicprobehook,quickandeasytodebug.

Basedonasimplewaveformgeneratorofthemicrocontrollerisacommonsource,iswidelyusedintheexperimentofelectronictechnology,automaticcontrolsystemandotherscientificfields[9].

Atpresent,thecompositionofsimplewaveformgeneratorTherearemanyways,suchastypeofDDS(Direct2DigitalSynthesis)arbitrarywaveformgenerator,usingadedicatedsignalchipMAX038AWG.Thedesignstemsfromthe2007NationalUndergraduateElectronicsystemtocontest,throughanalysisandcomparisonwithtraditionalmethodstoachievethemulti-functionwaveformgenerator[10].Withhigh-performancesingle-chiphighspeedofoperation,systemintegration,strongadvantages,thedesignofthissignalgenerator,digitalsignalgeneratorthantheprevioushardwareissimpletounderstandandimplementeasier,clearerdesignideasfortheprogram,andeasytocontrolandtheadvantagesofthefrequencyandamplitude[11].

Thelow-frequencysignalgeneratorwiththesynthesisofsingle-chipwaveformgeneratortoproducehigh-precision,lowdistortionsinewavevoltagecanbeusedforthecalibrationfrequencyrelays,synchronizationrelays,etc.canalsobeusedasalow-frequencyinverterpowersupply.

Microcontrollerasthecoredesignofalowfrequencyfunctionsignalgenerator.Signalgeneratorwithdigitalwaveformsynthesistechniques,throughacombinationofhardwarecircuitryandsoftwareprogramscanoutputcustomwaveformssuchassine,square,trianglespreadtootherarbitrarywaveform.Waveformfrequencyandamplitudecanbearbitrarilychangedwithinacertainrange.Waveformgenerationprinciple,hardwareandsoftwarepartofthedesignprinciples.MCUcontroltheD/Aconvertertoproducesignalsabovehardwareandsoftwareprogramming,ofDAC0832D,/Aconverterprincipleanduse,AT89C52andrelatedtothedesignofthecircuitchip,ondifferentlow-frequencysignalsourcedesign.Thesignalgeneratorhastheadvantagesofsmallsize,lowprice,stableperformance,fullyfunctional.2SystemDesign

2.1program:

AT89C52microcontrollerprogrammingmethodtoproducesawtooth,sinewave,squarewavethreewaveforms,andthenthroughtheD/AconverterDAC0832digitalsignalconvertedtoanalogsignals,filteredandamplified,andultimatelybytheoscilloscopedisplay,andkeyboardtocontrolthreetypesofwaveformsofthefrequencychanges,thefinaloutputshowsthetypeandvalue.

Designrequirements

1),theuseofsingle-chipsoftwaredesignproducesthreewaveforms

2),threewaveformscanbeselectedviathekeyboard

3)Thewaveformfrequencyisadjustable

4),needtodisplaythewaveformtypesandfrequency

2.2deviceselection

1bytheMCUtocontroltheD/Aoutputthreekindsofwaveforms.

AT89C52microcontrollerisahigh-performance8-bitsinglechipmicrocomputer.Whichconstitutethecomputer'scentralprocessingunitCPU,memory,registers,theI/Ointerfacetoproductioninanintegratedcircuitchip,whichconstitutearelativelycompletecomputer,anditscheap.

3,theLCDmonitor1602.Itspowerissmall,theeffectisobvious,anddisplaytheprogrammingiseasytocontrol,youcandisplaytheletters.2.3Theoverallsystemdesign

ThesystemusesamicrocontrollerasthedataprocessingandcontrolofthecorebytheMCUtocompletetheman-machineinterface,systemcontrol,signalacquisitionandsignalprocessingandtransformation,usingkeystrokes,usetheLCDdisplayofthecircuitoutputdigitalprogram.Thedesigntaskisbrokendownintokeycircuits,liquidcrystaldisplaycircuitmodules.Figure2-1showstheoverallblockdiagramofthesystem2.4HardwareImplementationandunitcircuitdesign

2.4.1ofthesmallestsingle-chipsystemdesign

The89C52chip,ROM/EPROMMCU,thischipconstitutetheminimumsystemsimple,andreliable.Constitutetheminimumapplicationsystemusingthe89C52microcontrollerconnectedtotheclockcircuitandresetcircuitcanbeshownintheFigure89C51microcontrollerminimumsystem.Duetothelimitofintegration,theminimumapplicationcanonlybeusedasasmallcontrolunit.Itsapplicationfeatures:

(1)availabletousersofalargenumberofI/Oportlines.

(2)Internalmemorycapacityislimited.

(3)applicationdevelopmentisunique.

Thestandard52forthe8Kprogramspace,128bytesofRAM,32ports,fiveinterrupts,twotimer/counter,12clockcyclestoexecuteabasicinstruction,thedivisionofthelongestfor48cycles.52forthe8Kprogramspace,and256bytesofRAM,32ports,sixinterrupt,threetimer/counters.2.4.2D/Aconverter

TheDAC0832isadualin-line8-bitD/Aconverter.Abletocompletethedigitalinputtoanalogoutput(current)conversion.Figure3.5showsthepindiagramoftheDAC0832.Itsmainparametersareasfollows:resolutionof8,theconversiontimeof1μs,fullscaleerrorof±1LSB,thereferencevoltage(+10/span>-10)V,powersupply(+5to+15)VlogiclevelinputscompatiblewithTTL.BeseenfromFigure3-1,theDAC0832intwolatchesthefirstlatchiscalledtheinputregister,itallowsthelatchedsignalasILE,thesecondlatchcalledtheDACregister,itthelatchsignalisalsoreferredtoasachannelcontrolsignal/XFER.Figure2-3,whentheILEishigh,thechipselectsignal/CSandthewritesignal/WR1islow,theinputregistercontrolsignal,inwhichcase,theoutputoftheinputregisterwiththeinputchanges.Thereafter,whenthehigh/WR1low,thecontrolsignalsbecomelowatthistime,thedataislatchedintotheinputregister,inputregisteroutputisnolongerwiththechangeoftheexternaldataDB.Thesecondstagelatchtransfercontrolsignal/XFERandwritesignal/WR2atthesametimeislow,thetwolatchcontrolsignalishigh,theoutputofthe8-bitDACregisterwiththeinput,thenwhen/WR2fromlow,thecontrolsignalgoeslow,sotheinputregisterislatchedintotheDACregister.

Figure2-3therestofthepinfunctiondefinedasfollows:

(DI7~DI0in:1)8-bitdatainput,DI7highest.

(2)IOUT1:analogcurrentoutputterminal1,whenthedataintheDACregisterareall1,themaximumoutputcurrent,theDACregisterdataareall0,theoutputcurrentis0.

(3)IOUT2​​:analogcurrentoutput,IOUT2​​andIOUT1andisaconstant,thatisIOUT1the+IOUT2​​=constant.

(4)theRFB:feedbackresistorterminalofDAC0832internalfeedbackresistor,RFB-sidecanbedirectlyconnectedtoanexternalopamp'soutput,thisisequivalenttoafeedbackresistorconnectedtotheopampoutputandinput.

(5)VREF:Referencevoltageinput,thisendcanbeconnectedtoapositivevoltagecanbeaccessedbyanegativevoltage,whichdeterminesthe0-255digitaltransformingtheamplitudeoftheanalogvoltagevalues​​,VREFrange(+10-10)V.ResistornetworkconnectedtothetheVREFsideandD/AinternalT-shaped.

(6)Vcc:chipsupplyvoltagerangeof(+5-15)V.2.4.3opampcircuitFigure2-4,R1iscoupledtoresistors,R2,R3,resistorvoltagedividerfeedback.R2andR1,thevoltageratioof1:2,forOUT2voltageof-5v~0vinthesecondopampinthemake-5v~0vbetweenthevoltagechange-5vto5v,thefirstopampconverttheamountofvoltagevaluesdidnotincreaseordecreasethe1v,thesecondstageopampvoltagedecreaseorincreaseof2v.2.4.4LEDdisplayinterfacecircuit

CommonlyusedinLEDdisplayLEDstatusdisplay(commonlyknownaslight-emittingdiode)LEDseven-segmentdisplay(commonlyknownasthedigitalcontrolandLED16segmentdisplay,LEDdisplaytwostates,forthesystem;digitaltubefordigitaldisplay;LED16segmentdisplay,forthecharacterdisplay)

A.Digitalcontrolstructure

Digitaltubeconsistsofeightlight-emittingdiode(hereinafterreferredtoasfields),differentcombinationscanbeusedtodisplaythenumbers0-9.CharactersAFandthedecimalpoint"."Digitaltubeisdividedintotwocommoncathodeandcommonanodestructure.

Digitalpipeworks

Totalanode8digitaltubelightemittingdiodeanode(diodepositiveterminal)connectedtogether.Usuallycommonanodeconnectedhighageneralpowersupplywhenacathodeconnectedtolow,thedigitaltubeconductionandlight.Atotalofeightlight-emittingdiodedigitalcathodetubecathode(diodenegativeterminal)connectedtogether.Publiccathodeconnectedtolow(ground)whenananodeconnectedtohigh,thedigitaltubelight.2.4.5WaveformGenerationPrincipleandmoduledesign

1First,thedigitalvalueofthestoredwaveformmemoryarraytosin;52microcontrollertoreadthevalueinthearrayintotheD/Aconverter;

3,D/Aconverterinputdigitalvalueisconvertedtoanalogoutput;

4,theD/Aanalogoutputelectriccurrentthroughtheopamptoconvertthevoltageoutput.ThreewaveformsgeneratedbythemicrocontrollerprogrammingmethodthroughtheDAconvertermoduleDAC0832outputintothefilterwaveamplification.Schematic2-6asfollows:2.4.6thedesignofthedisplaymodule

LCD1602displaytheoutputwaveform,frequency,thecircuitdiagram.AsshowninFigure2-7,the1602dataoftheeightterminationmicrocontrollerP1port,itsthreeP3.2-P3.4canendRS,RW,,E,respectively,thenthemicrocontroller.ThroughsoftwarecontroloftheLCDscreencandisplaythewaveformtypesandfrequencyofthewaveform.附录E中文原文波形发生器即简易函数信号发生器，是一个能够产生多种波形，如三角波、锯齿波、方波、正弦波等波形电路。函数信号发生器在电路实验和设备仪器中具有十分广泛的用途。通过对函数发生器的原理以及构成分析，可设计一个能变换出三角波、锯齿波、方波、正弦波的函数波形发生器。在工业生产和科研中利用函数信号发生器发出的信号，可以对元器件的性能及参数进行测量，还可以对电工和电子产品进行指数验证、参数调整及性能鉴定。常用的信号发生器绝大部分是由模拟电路构成的，当这种模拟信号发生器用于低频信号输出往往需要的RC值很大，这样不仅参数准确度难以保证，而且体积和功耗都很大，而由数字电路构成的低频信号发生器，虽然其性能好但体积较大，价格较贵，因此，高精度，宽调幅将成为数字量信号发生器的趋势。本文介绍的是利用89C52单片机和数模转换器件DAC0832产生所需不同信号的低频信号源，其信号幅度和频率都是可以按要求控制的。文中简要介绍了DAC0832数模转换器的结构原理和使用方法，89C52的基础理论，以及与设计电路有关的各种芯片。文中着重介绍了如何利用单片机控制D/A转换器产生上述信号的硬件电路和软件编程。信号频率幅度也按要求可调。1引言单片机是一种集成在电路芯片，是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计算机系统。波形发生器是一种数据信号发生器，在调试硬件时，常常需要加入一些信号，以观察电路工作是否正常。用一般的信号发生器，不但笨重，而且只发一些简单的波形，不能满足需要。例如用户要调试串口通信程序时，就要在计算机上写好一段程序，再用线连接计算机和用户实验板，如果不正常，不知道是通讯线有问题还是程序有问题。用E2000/L的波形发生器功能，就可以定义串口数据。通过逻辑探勾输出，调试起来简单快捷。基于单片机的简易波形发生器是一种常用的信号源,它广泛地应用在电子技术实验、自动控制系统和其他科研领域。目前,简易波形发生器的构成方法有很多,例如采用DDS(Direct2DigitalSynthesis)型的任意波发生器、采用专用的信号发生芯片MAX038以及传统的AWG。本设计源于2007年全国大学生电子制做大赛,通过分析比较后采用传统的方法来实现多功能波形发生器。借助高性能单片机运算速度高,系统集成度强的优势,设计的这种信号发生器,比以前的数字式信号发生器具有硬件简单,理解及实现起来较容易,该方案的设计思路较为清晰,且容易对频率和幅值进行控制等优点。低频信号发生器采用单片机波形合成发生器产生高精度，低失真的正弦波电压，可用于校验频率继电器，同步继电器等，也可作为低频变频电源使用。以单片机为核心设计了一个低频函数信号发生器。信号发生器采用数字波形合成技术,通过硬件电路和软件程序相结合,可输出自定义波形,如正弦波、方波、三角波及其他任意波形。波形的频率和幅度在一定范围内可任意改变。介绍了波形的生成原理、硬件电路和软件部分的设计原理。介绍了单片机控制D/A转换器产生上述信号的硬件电路和软件编程、DAC0832D/A转换器的原理和使用方法、AT89C52以及与设计电路有关的各种芯片、关于产生不同低频信号的信号源的设计方案。该信号发生器具有体积小、价格低、性能稳定、功能齐全的优点。2系统设计2.1方案：利用AT89C52单片机采用程序设计方法产生锯齿波、正弦波、矩形波三种波形，再通过D/A转换器DAC0832将数字信号转换成模拟信号，滤波放大，最终由示波器显示出来，通过键盘来控制三种波形的类型选择、频率变化，最终输出显示其各自的类型以及数值。设计要求1)、利用单片机采用软件设计方法产生三种波形2）、三种波形可通过键盘选择3）、波形频率可调4）、需显示波形的种类及其频率2.2器件选择1、通过单片机控制D/A，输出三种波形。2、AT89C52单片机是一种高性能8位单片微型计算机。它把构成计算机的中央处理器CPU、存储器、寄存器、I/O接口制作在一块集成电路芯片中，从而构成较为完整的计算机、而且其价格便宜。3、采用LCD液晶显示器1602。其功率小，效果明显，显示编程容易控制，可以显示字母。2.3总体系统设计该系统采用单片机作为数据处理及控制核心，由单片机完成人机界面、系统控制、信号的采集分析以及信号的处理和变换，采用按键输入，利用液晶显示电路输出数字显示的方案。将设计任务分解为按键电路、液晶显示电路等模块。2.4硬件实现及单元电路设计2.4.1单片机最小系统的设计89C52是片内有ROM/EPROM的单片机，因此，这种芯片构成的最小系统简单﹑可靠。用89C52单片机构成最小应用系统时，只要将单片机接上时钟电路和复位电路即可，如图89C51单片机最小系统所示。由于集成度的限制，最小应用系统只能用作一些小型的控制单元。其应用特点：有可供用户使用的大量I/O口线。内部存储器容量有限。应用系统开发具有特殊性。标准的52为8K程序空间，128字节的RAM，32条端口，5个中断，2个定时/计数器，12个时钟周期执行一条基本指令，最长的除法为48个周期。52为8K程序空间，256字节的RAM，32条端口，6个中断，3个定时/计数器。2.4.2D/A转换器DAC0832是双列直插式8位D/A转换器。能完成数字量输入到模拟量(电流)输出的转换。图3.5为DAC0832的引脚图。其主要参数如下