自动化专业基于单片机的LED显示屏的设计与Proteus仿真外文文献翻译及原文.docx

自动化专业基于单片机的LED显示屏的设计与Proteus仿真外文文献翻译及原文.docx

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外文文献翻译

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基于单片机的LED显示屏的设计与Proteus仿真文献、资料英文题目：

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翻译日期:

2017.02.14

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英文原文

LEDDisplayScreenDesignandProteusSimulationBasedonSingle-ChipMicrocomputer

Abstract—ThispaperdesignsaLEDdisplaysystemcontrolledbyAT89C52MCU（MicrocomputerControllerUnit）.TheAT89C52controlstheexternalcircuitformedby74HC154andusedtocontroltherealtimedisplay.LanguageCisappliedtocompileprograminKeiluVision3programmingenvironment.ThedisplaysystemissimulatedthroughProteussoftware.InProteusenvironment，theschematicdiagramisdrawn.Throughstimulation，itachievesreal-timedisplay,staticdisplayanddynamicdisplayofChinesecharacters.Ithasswitchkeystochangedisplaystateofdetails.Throughtheactualsimulation，thebiggestcontrollablescreensizeoftheAT89C52MCUis64x32.TheAT89C52controlstheentirescreendisplayofChinesecharactersof16x16dotmatrix,atotalofeightcharacters.Andthekeyfunctioncanbeextended.

Keywords-LEDdisplay;AT89C52;Proteus;dynamicscanning

I.INTRODUCTION

Energy-savingissueattractseveryone5sattention.Thustheproductsthatfocusonenergyconservationgetmorerecognition.LED（LightEmittingDiode-LED）displayproducedinthe1970swhenitwassimplyusedtodisplaynumberandtext.WiththediversificationofLedcolorsandenhancementofbrightness，fullcoloroutdoorsLEDdisplaybecamearealityattheendofthe20thcentury.TheLEDofourcountryappearedinthe1970sanditsindustrialproductioninthe1980s.ThedevelopmentofinformationandadvertisingindustrybringsabouttheemergenceofLEDdisplayscreen.LEDdisplayscreensaremainlyusedinadvertisingwindow,trainstations,banksandotherplaces.Itgetsmoreandmorewidelyused.Itsowncharacteristicscouldmakeitoccupyamarketinthedisplayscreenindustryinthefuture.

InthedesignofLEDdisplay,thehardestpartishardwaredebug.Inorderto

soIvethesignaIinterference,insufficientsoIderinhardwareconnection,componentdamageandaseriesofdebuggingproblems,theEDA（ElectronicDesignAutomation-EDA）utilitysoftwareProteusthattheUKLabcentereIectronicscompanyresearchedcanbeusedtorealizetheentirehardwaresystemschematicdrawingandsimulation[1].

ProteussimulationenvironmentincludesISISandARES.IntheISISenvironment，electroniccircuitcanbedirectlystimulatedinthestageofschematic.Italsoprovidesvirtualmachines,simulationoftheinputsignalwhichmakesaconvenientsimulation.ARESismainlyusedforPCB（PrintedCircuitBoard-PCB）design.Thedevicelibraryprovidesschematicdeviceanditspackage.Itcandesignprintedcircuitboardin

thisenvironment.

ProteussimulationsystemcurrentlysupportsMCU（MicroControlIerUnit-

MCU）withARM7,8051/52series,AVRseries,PIC10/12/16/18series,HC11seriesandtheMSP430[2].Itcanobservethedirectresultofhardwaredebugwithproteussimulation.Ithasthecharacterssuchasintuitive,convenient,costsavings,highefficiencyandsoon.

II.THEDESIGNOFLEDDISPLAY

LEDdisplaysystemisformedbyMCU,LEDscreendisplaycircuit,externaIcircuitandtheprogramforcontrolthesystem.LEDscreendisplaycircuitincludesLEDpaneIandthedrivingcircuitofrowandcolumn.TheexternaIfunctioncircuitincludeskeycontrollingcircuitandreaI-timeclockcircuit.DisplayfunctioncanbeachievedasfolIows:

numbers,characters,Chinesecharacters,staticdisplayofmonochromepictures,anddynamicdisplay.DynamicdisplayincIudesthewholedisplaycontentmovingupandIeft.Theshiftmethodiscontrolledbykeys,andalsobyautomaticcycle.Thesystemofreal-timeclockdisplayprovidesseconds,minutes,hours,day，date,month,andyearinformation.TheoverallblockdiagramofLEDdisplayscreenisshowninFig.1.

F^ure1.TheoverallblockdiagramofLEDdisplayscreen

III. HARDWAREDESIGNOF

LEDDISPLAY

A.DesignofRowDriving

Circuit

ThecoreofLED

displaysystemisthecontrol

circuit.The

controlcircuit

includesdrivingcircuit,clockcircuitandthesmallestMCUsystemwhichconsistsofAT89C52MCU,CrystalosciIIatorcircuitandresetcircuitRowdrivingchipis74HG154,4-to-16Iinedecoder/demultiplexer,activeLOWoutputs.

P2.0~P2.3portofAT89C52connecttoA0~A3of74HC154decoder.Accordingtotheoperatingprincipleofthedecoder,whentheMCUsystemcontrolsitsP2portoutput0x00~0x0F，the74HC154respectiveIy

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丽Y0YlY2Y3Y4Y5Y6Y7l710711^Y14^

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PJXI

PJJ

PJ3

outputLOWIeveIfromYOtoY15.AndthenthefirstIinetothesixteenthlineofdisplayscreenisselected.TheP2.4portofMCUconnectstothefirst74HC154decoder9s（1~16linecontroller）enablepins，meanwhileconnectstothesecondoneenablepins（17~32linecontroller）throughinverters.Thatrealizeslinescanningmethod.Whenscanningfromthefirstlinetothesixteenthline，theP2.4port’soutputisjumpfrom0to1.Andenablethesecond74HC154:

theseventeenthlineisoutput.ThismethodachievesscanofIow-haIfLEDdispIay.TherowdrivingcircuitdiagramisshowninFig.2.

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Tx

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Figure2.Rowdrivingcircuitdiagram

B.DesignofColumnDrivingCircuit

P1.0~P1.2portsofMCUareusedtocontrolthecolumndrivingchipMC74HC595.74HG595isshiftregisterwithan8-bitserialin,serialorparalleloutwithoutputlatches3states.Itscontrolclockandshiftclockareseparatethatbringsconvenienceforcontrolling.Eachcharacteriscomposedbydotmatrixof16rowsand16columns:

eachcharacterofnationalstandardChinesecharacterIibraryisrepresentby256dotsmatrix[3].Thefontsoftwaregeneratescodeofdotmatrixwhichishexadecimalnumberof8bitagroup.Inthisdesignrowscanisused,sothehorizontalfontcodeistaken.Using74HC595tocontrolthecolumndatasendout.Whenusing74HC595tocontroleachcharacterscodedisplay,P1.0portofMCUwillsend8bitserialdatafromthefirstcolumntotheeighthcolumn,whichishighafterthepreviouslowinthistransmission.P1.2portofMCUoutputsshiftclock.WhenP1.0portoutputsabitdata,theelectricalIeveIofP1.2portchangesfromlowtohighonce,thenthecontentofshiftregister74HC595willmoveonebitfromthehightothelowonce.WhentheninthbitdataissenttoSDIportof74HC595,the74HC595’sSDOportwillseriallyoutputthefirstbitintheshiftregistertotheeighthbitofthenext74HC595chip,andthenewincomingdataissenttotheeighthinthefirstchip.Aftertheendofthedatapreparation

fromthe1stcolumntothe64thcolumn,P1.1portgeneratesarisingedgepulsewhichsendstotheLCHCLKportof74HC595.Firstlyputting74HC595chipincascadeconnection,thenconnectingtheparaIIeIoutputclockpinsinseriesandtheseclockpinsarecontrolledbyP1.1port.Therefore,whentheoutputclockisvalid,every74HC595”scolumndataoutputatthesametime.Thentoachievedisplaysthiswholerowbyselectingthehomologousrow.Continuingtodothesteps,itcanreaIizearowscan.AsIongastheentirescreenofthescanrateishighethan50timesperseconds,peoplecouldseestaticimages.The74HC595columndrivingcircuitisshowninFig.3

Figure3.74HC595columndrivingcircuit

C.DesignofFunctionalCircuit

Besidestheabovefunction,thedesignalsohasrealtimedisplayandthekeyfunctiontoswitchthedisplaymodes.P3.0~P3.3portsindividuallyconnecttofourbuttonswhichcontrolstaticdisplay,movingupdispIay,movingIeftdisplayandautomaticeyeIedispIay.Theautomaticcycledisplayisfromthestatic,movinguptomovingIeftcircleshows.Thefunctionisrealizedbyprogrammingofkeyscan.DS1302chipisusedtocontrolrealtimeclock.Thetimeinformationsuchassecond,minute，hour,day,date,month,andyearisdisplayedinLEDdisplayscreen.A3.6VbuttonbatteryisconnectedtotheeighthpinofDS1302,whichensuresDS1302continuousoperationwhileLEDdisplaysystemdoesnotwork[4].ThreedatawiresareusedtocontrolDS1302inordertoachievesynchronousserialcommunication.TheP3.6portofMCUcontrolsserialclockSCLKpin,P3.7portcontrolstheDS1302’sREST/RSTpin,andP3.5connectstodataIineI/O.AccordingtotheoperatingprincipIeofDS1302,MCUreadsandwritesthedata，thensendstodisplayinLEDpanel.ThefunctioncircuitandtheMCUsystemdiagramareshowninFig4.

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Figure4.FunctionalcircuitandtheMCUsystemdiagram

IV.SOFTWAREDESIGN

UsingClanguagetowritetheprogram,theprogramiscompiledinKeiluVision3developmentenvironmentTheprogramusesmodulardesign,whichisasfollows:

timedelayfunction,74HC595performancefunction,DS1302controlfunction,datadisplayfunctionandthemainfunction.ThemodulardesignofLEDdisplayprogramisconvenientforwritingandchanging.

Fig.5isthemainfunctionblockdiagram.Itmainlyrealizestheoverallinitialization,DS1302initializationandkeyscan.Whenthemainfunctionisprogrammed，subfunctionshouldbeplacedbeforethemainfunction,ordeclaredinadvance.Keyscanincludesfourfunctionkeys,which

respectivelyaccompIishthemovingup,Ieft,cyclicandstaticdisplay.

Fig.6isDS1302initializationfunctionbIockdiagram.ThefunctionreaIi

zesDS1302internaIvariabIeinitialization，prohibitingwriteprotection,sendingtheaddressofwr