电子信息毕业设计外文翻译微型计算机控制系统(单片机控制系统)

11毕业设计外文资料翻译Graduationdesignforeignlanguagetranslation学 院： 电气工程与自动化学院专业班级： 电子信息科学与技术三班学生姓名：学 号：10外文资料：MicrocomputerSystemsElectronicsystemsareusedforhandinginformationinthemostgeneralsense;thisinformationmaybetelephoneconversation,instrumentreadoracompany‟saccounts,butineachcasethesamemaintypeofoperationareinvolved:theprocessing,storageandtransmission of information. in conventional electronic design these operations arecombinedatthefunctionlevel;forexampleacounter,whetherelectronicormechanical,storesthecurrentandincrementsitbyoneasrequired.Asystemsuchasanelectronicclockwhichemployscountershasitsstorageandprocessingcapabilitiesspreadthroughoutthesystembecauseeachcounterisabletostoreandprocessnumbers.Present day microprocessor based systems depart from this conventionalapproachbyseparatingthethreefunctionsofprocessing,storage,andtransmissionintodifferentsectionofthesystem.ThispartitioningintothreemainfunctionswasdevisedbyVonNeumannduringthe1940s,andwasnotconceivedespeciallyformicrocomputers.Almosteverycomputerevermadehasbeendesignedwiththisstructure,anddespitetheenormousrangeintheirphysical forms,theyhaveallbeenofessentiallythesamebasicdesign.Inamicroprocessorbasedsystemtheprocessingwillbeperformedinthemicroprocessor itself. The storage will be by means of memory circuits and thecommunicationofinformationintoandoutofthesystemwillbebymeansofspecialinput/output(I/O)circuits.Itwouldbeimpossibletoidentifyaparticularpieceofhardwarewhichperformedthecountinginamicroprocessorbasedclockbecausethetimewouldbestoredinthememoryandincrementedatregularintervalsbutthemicroprocessor.However,thesoftwarewhichdefinedthesystem‟sbehaviorwouldcontainsectionsthatperformedascounters.Theapparentlyratherabstractapproachtothearchitectureofthemicroprocessoranditsassociatedcircuitsallowsittobeveryflexibleinuse,sincethesystemisdefinedalmostentirelysoftware.Thedesignprocessislargelyoneofsoftwareengineering,andthesimilarproblemsofconstructionandmaintenancewhichoccurinconventionalengineeringareencounteredwhenproducingsoftware.Thefigure1-1illustrateshowthesethreesectionswithinamicrocomputerareconnectedintermsofthecommunicationofinformationwithinthemachine.Thesystemiscontrolledbythemicroprocessorwhichsupervisesthetransferofinformationbetweenitselfandthememoryandinput/outputsections.Theexternalconnectionsrelatetotherest(thatis,thenon-computerpart)oftheengineeringsystem.Fig.1-1ThreeSectionsofaTypicalMicrocomputerAlthoughonlyonestoragesectionhasbeenshowninthediagram,inpracticetwodistincttypesofmemory RAMandROMareused. Ineachcase,theword„memory‟isratherinappropriatesinceacomputersmemoryismorelikeafilingcabinetinconcept;informationisstoredinasetofnumbered„boxes‟anditisreferencedbytheserialnumberof the„box‟inquestion.MicrocomputersuseRAM(RandomAccessMemory)intowhichdatacanbewrittenandfromwhichdatacanbereadagainwhenneeded.Thisdatacanbereadbackfromthememoryinanysequencedesired,andnotnecessarilythesameorderinwhichitwaswritten,hencetheexpression„random‟accessmemory.AnothertypeofROM(ReadOnlyMemory)isusedtoholdfixedpatternsofinformationwhichcannotbeaffectedbythemicroprocessor;thesepatternsarenotlostwhenpowerisremovedandarenormallyusedtoholdtheprogramwhichdefinesthebehaviorofamicroprocessorbasedsystem.ROMscanbereadlikeRAMs,butunlikeRAMstheycannotbeusedtostorevariableinformation.SomeROMshavetheirdatapatternsputinduringmanufacture,whileothersareprogrammablebytheuserbymeansofspecialequipmentandarecalledprogrammableROMs.ThewidelyusedprogrammableROMsareerasablebymeansofspecialultravioletlampsandarereferredtoasEPROMs,shortforErasableProgrammableReadOnlyMemories.Othernewtypesofdevicecanbeerasedelectricallywithouttheneedforultraviolet light, which are called Electrically Erasable Programmable Read OnlyMemories,EEPROMs.Themicroprocessorprocessesdataunderthecontroloftheprogram,controllingtheflowofinformationtoandfrommemoryandinput/outputdevices.Someinput/outputdevicesaregeneral-purposetypeswhileothersaredesignedforcontrollingspecialhardwaresuchasdiscdrivesorcontrollinginformationtransmissiontoothercomputers.MosttypesofI/Odevicesareprogrammabletosomeextent,allowingdifferentmodesofoperation,whilesomeactuallycontainspecial-purposemicroprocessorstopermitquitecomplexoperationstobecarriedoutwithoutdirectlyinvolvingthemainmicroprocessor.Themicroprocessorprocessesdataunderthecontroloftheprogram,controllingtheflowofinformationtoandfrommemoryandinput/outputdevices.Someinput/outputdevicesaregeneral-purposetypeswhileothersaredesignedforcontrollingspecialhardwaresuchasdiscdrivesorcontrollinginformationtransmissiontoothercomputers.MosttypesofI/Odevicesareprogrammabletosomeextent,allowingdifferentmodesofoperation,whilesomeactuallycontainspecial-purposemicroprocessorstopermitquitecomplexoperationstobecarriedoutwithoutdirectlyinvolvingthemainmicroprocessor.Themicroprocessor,memoryandinput/outputcircuitmayallbecontainedonthesameintegratedcircuitprovidedthattheapplicationdoesnotrequiretoomuchprogramordatastorage. Thisisusuallythecaseinlow-costapplicationsuchasthecontrollersusedinmicrowaveovensandautomaticwashingmachines.Theuseofsinglepackageallowsconsiderablecostsavingstoemadewhenarticlesaremanufacturedinlargequantities.Astechnologydevelops,moreandmorepowerfulprocessorsandlargerandlargeramountsofmemoryarebeingincorporatedintosinglechipmicrocomputerswithresultingsavinginassemblycostsinthefinalproducts.Fortheforeseeablefuture,however,itwillcontinuetobenecessarytointerconnectanumberofintegratedcircuitstomakeamicrocomputerwheneverlargeramountsofstorageorinput/outputarerequired.Anothermajorengineeringapplicationofmicrocomputersisinprocesscontrol.Herethepresenceofthemicrocomputerisusuallymoreapparenttotheuserbecauseprovisionisnormallymadeforprogrammingthemicrocomputerfortheparticularapplication.Inprocesscontrolapplicationsthebenefits lffittingtheentiresystem ontosinglechip usuallyoutweighedbythehighdesigncostinvolved,becausethissortlfequipmentisproducedinsmallerquantities.Moreover,processcontrollersareusuallymorecomplicatedsothatitismoredifficulttomakethemassingleintegratedcircuits.Twoapproachesarepossible;thecontrollercanbeimplementedasageneral-purposemicrocomputerratherlikeamorerobustversionlfahobbycomputer,orasa„packaged‟system,signedforreplacingcontrollersbasedonoldertechnologiessuchaselectromagneticrelays.Intheformercasethesystemwouldprobablybeprogrammedinconventionalprogramminglanguages such as the ones to9 be introduced later, while in the other case aspecial-purposelanguagemightbeused,forexampleonewhichallowedthefunctionofthecontrollertobedescribedintermsofrelayinterconnections,IneithercaseprogramscanbestoredinRAM,whichallowsthemtobealteredtosuitchangesinapplication,butthismakestheoverallsystemvulnerabletolosslfpowerunlessbatteriesareusedtoensurecontinuityofsupply.AlternativelyprogramscanbestoredinROM,inwhichcasetheyvirtuallybecomepartoftheelectronic„hardware‟and areoftenreferredtoasfirmware.Moresophisticatedprocesscontrollersrequireminicomputersfortheirimplementation,althoughtheuselflargescaleintegratedcircuits„thedistinctionbetweenminiandmicrocomputers,Productsandprocesscontrollersofvariouskindsrepresentthemajorityof present-day microcomputer applications, the exact figures depending on interpretationoftheword„product‟.Virtuallyallengineeringandscientificusesofmicrocomputers can be assigned to one or other ofthesecategories.ButinthesystemwemoststudyPressureandPressureTransmitters.Pressureariseswhenaforceisappliedoveranarea.ProvidedtheforceisoneNewtonanduniformlyovertheareaofonesquaremeters,thepressurehasbeendesignatedonePascal.Pressureisauniversalprocessingcondition.Itisalsoaconditionoflifeontheplanet:weliveatthebottomofanatmosphericoceanthatextendsupwardformanymiles.Thismassofairhasweight,andthisweightpressingdownwardcausesatmosphericpressure.Water,afundamentalnecessityoflife,issuppliedtomostofusunderpressure.Inthetypicalprocessplant,pressureinfluencesboilingpointtemperatures,condensingpointtemperatures,processefficiency,costs,andotherimportantfactors.Themeasurementandcontrolofpressureorlackofit-vacuum-inthetypicalprocessplantiscritical.Theworkinginstruments intheplantusuallyincludesimplepressure precisionrecordersandindicators,andpneumaticandelectronicpressuretransmitters.Apressuretransmittermakesapressuremeasurementandgenerateseitherapneumaticorelectricalsignaloutputthatisproportionaltothepressurebeingsensed.Intheprocessplant,itisimpracticaltolocatethecontrolinstrumentsoutintheplaceneartheprocess.Itisalsotruethatmostmeasurementsarenoteasilytransmittedfromsomeremotelocation.Pressuremeasurementisanexception,butifahighpressureofsomedangerouschemicalistobeindicatedorrecordedseveralhundredfeetfromthepointofmeasurement,ahazardmaybefromthepressureorfromthechemicalcarried.Toeliminatethisproblem,asignaltransmissionsystemwasdeveloped.Thissystemisusuallyeitherpneumaticorelectrical.Andcontrolinstrumentsinonelocation.Thismakesitpracticalforaminimumnumberofoperatorstoruntheplantefficiently.Whenapneumatictransmissionsystemisemployed,themeasurementsignalisconvertedintopneumaticsignalbythetransmitterscaledfrom0to100percentofthemeasurementvalue.Thistransmitterismountedclosetothepointofmeasurementintheprocess.Thetransmitteroutput-airpressureforapneumatictransmitter-ispipedtotherecordingorcontrolinstrument.Thestandardoutputrangeforapneumatictransmitteris20to100kPa,whichisalmostuniversallyused.Whenanelectronicpressuretransmitterisused,thepressureisconvertedtoelectricalsignalthatmaybecurrentorvoltage.Itsstandardrangeisfrom4to20mADCforcurrentsignalorfrom1to5VDCforvoltagesignal.Nowadays,anothertypeofelectricalsignal,whichisbecomingcommon,isthedigitalordiscretesignal.Theuseofinstrumentsandcontrolsystemsbasedoncomputerorforcingincreaseduseofthistypeofsignal.Sometimesitisimportantforanalysistoobtaintheparametersthatdescribethesensor/transmitterbehavior.Thegainisfairlysimpletoobtainoncethespanisknown.Consideranelectronicpressuretransmitterwitharangeof0～600kPa.ThegainisKr

20mA4mA

16mA

mA0.027600kPa0kPa 600kPa kPadefinedasthechangeinoutputdividedbythechangeininput.Inthiscase,theoutputiselectricalsignal(4～20mADC)andtheinputisprocesspressure(0～600kPa).Thusthegain.BesidewemustmeasureTemperatureTemperaturemeasurementisimportantinindustrial control, as direct indications of system or product state and as indicationsofsuchfactorsasreactionrates,energyflow,turbineefficiency,andlubricantquality.Presenttemperaturescaleshavebeeninuseforabout200years,theearliestinstrumentswerebasedonthethermalexpansionofgasesandliquids.Suchfilledsystemsarestillemployed,althoughmanyothertypesofinstrumentsareavailable.Representativetemperature sensors include: filled thermal systems, liquid-in-glass thermocouples,resistancetemperaturedetectors,thermostats,bimetallicdevices,opticalandradiationpyrometersandtemperature-sensitivepaints.Advantagesofelectricalsystemsincludehighaccuracyandsensitivity,practicalityofswitchingorscanningseveralmeasurementspoints,largerdistancespossiblebetweenmeasuringelementsandcontrollers,replacementofcomponents(ratherthancompletesystem),fastresponse,andabilitytomeasurehighertemperature.Amongtheelectricaltemperaturesensors,thermocouplesandresistancetemperaturedetectorsaremostwidelyused.DescriptionTheAT89C51isalow-power,high-performanceCMOS8-bitmicrocomputerwith4KbytesofFlashprogrammableanderasablereadonlymemory(PEROM).ThedeviceismanufacturedusingAtmel‟shigh-densitynonvolatilememorytechnologyandiscompatiblewiththeindustry-standardMCS-51instructionsetandpinout.Theon-chipFlashallowstheprogrammemorytobereprogrammedin-systemorbyaconventionalnonvolatilememoryprogrammer.Bycombiningaversatile8-bitCPUwithFlashonamonolithicchip,theAtmelAT89C51isapowerfulmicrocomputerwhichprovidesahighly-flexibleandcost-effectivesolutiontomanyembeddedcontrolapplications.FunctioncharacteristicTheAT89C51providesthefollowingstandardfeatures: 4KbytesofFlash, 128bytesofRAM,32I/Olines,two16-bittimer/counters,afivevectortwo-levelinterruptarchitecture,afullduplexserialport,on-chiposcillatorandclockcircuitry.Inaddition,theAT89C51isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes.TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialportandinterruptsystemtocontinuefunctioning.ThePower-downModesavestheRAMcontentsbutfreezestheoscillatordisablingallotherchipfunctionsuntilthenexthardwarereset.PinDescriptionVCC：Supplyvoltage.Port0：Port0isan8-bitopen-drainbi-directionalI/Oport.Asanoutputport,eachpincansinkeightTTLinputs. When 1s are writtento port 0 pins, the pins canbe used ashighimpedanceinputs.Port0mayalsobeconfiguredtobethemultiplexedloworderaddress/databusduringaccessestoexternalprogramanddatamemory.InthismodeP0hasinternalpullups.Port0alsoreceivesthecodebytesduringFlashprogramming,andoutputsthecodebytesduringprogramverification.Externalpullupsarerequiredduringprogramverification.Port1Port1isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort1outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort1pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port1pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseoftheinternalpullups.Port1alsoreceivesthelow-orderaddressbytesduringFlashprogrammingandverification.Port2Port2isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort2outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort2pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port2pinsthatareexternallybeingpulledlowwillsourcecurrent,becauseoftheinternalpullups.Port2emitsthehigh-orderaddressbyteduringfetchesfromexternalprogrammemoryandduringaccessestoexternaldatamemorythat use 16-bit addresses. Inthis application,ituses stronginternalpullupswhenemitting1s.Duringaccessestoexternaldatamemorythatuse8-bitaddresses,Port2emitsthecontentsoftheP2SpecialFunctionRegister.Port2alsoreceivesthehigh-order address bits and some control signals during Flash programming andverification.Port3Port3isan8-bitbi-directionalI/Oportwithinternalpullups.ThePort3outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort3pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port3pinsthatareexternallybeingpulledlowwillsourcecurrent(IIL)becauseofthepullups.Port3alsoservesthefunctionsofvariousspecialfeaturesoftheAT89C51aslistedbelow:Port3alsoreceivessomecontrolsignalsforFlashprogrammingandverification.RSTResetinput.Ahighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetsthedevice.ALE/PROGAddressLatchEnableoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory.Thispinisalsotheprogrampulseinput(PROG)duringFlashprogramming.InnormaloperationALEisemittedataconstantrateof1/6theoscillatorfrequency,andmaybeusedforexternaltimingorclockingpurposes.Note,however,thatoneALEpulseisskippedduringeachaccesstoexternalDataMemory.Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH.Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction.Otherwise,thepinisweaklypulledhigh.SettingtheALE-disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode.PSENProgramStoreEnableisthereadstrobetoexternalprogrammemory.WhentheAT89C51isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexternaldatamemory.EA/VPPExternalAccessEnable.EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH.Note,however,thatiflockbit1isprogrammed,EAwillbeinternallylatchedonreset.EAshouldbestrappedtoVCCforinternalprogramexecutions.Thispinalsoreceivesthe12-voltprogrammingenablevoltage(VPP)duringFlashprogramming,forpartsthatrequire12-voltVPP.XTAL1Inputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingcircuit.XTAL2Outputfromtheinvertingoscillatoramplifier.OscillatorCharacteristicsXTAL1andXTAL2aretheinputandoutput,respectively,ofaninvertingamplifierwhichcanbeconfiguredforuseasanon-chiposcillator,asshowninFigure1.Eitheraquartzcrystalorceramicresonatormaybeused.Todrivethedevicefromanexternalclocksource,XTAL2shouldbeleftunconnectedwhileXTAL1isdrivenasshowninFigure2.Therearenorequirementsonthedutycycleoftheexternalclocksignal,sincetheinputtotheinternalclockingcircuitryisthroughadivide-by-twoflip-flop,butminimumandmaximumvoltagehighandlowtimespecificationsmustbeobserved.中文翻译：微型计算机掌握系统〔单片机掌握系统〕〔单片机掌握系统〕是用于处理信息的，这种被子计数器还是机械计数器，都要存储当前的数值，并且按要求将该数值增加1。一个由于每个计数器都能存储和处理一些数字。-2040年月所设想出来的，并且是计的计算机。/输出〔I/O〕电路。要在一个以微处理器为根底的时钟中找出执行具有计数功能的一个工程，而且在生产软件时，就会遇到产生于常规工程中相像的构造和维护问题。1-1微型计算机的三个组成局部图1-1显示出了微型计算机中这三个单元在一个微处理器掌握系统中是如何依据身的存储器和输入/输出单元的信息传输进展治理。外部的连接局部与工程系统中的其余局部〔即非计算机局部〕有关。RAMROM两种不同述的“存储器”一词是格外不恰当的；信息被存放在一系列已数字标记过的的“箱子”中，而且可以依据问题由“箱子”的序列号进展相关信息的参考定位。RA〔随机存取存储器RAM中，数据可以被“随机”存取存储器。另一ROM〔只读存储器〕是用来保持信息的，它们是不受微处理器影响的固定的信ROMRAMRAM不一样的是不能用来存储可变的信息。有些ROM在制造时将其数据标本放入，而另外的则可通过特别的设备由用ROMROM可利用特别紫外线灯察EPROM，即可察除可编程只读存储器的缩写。另有类型的期器件不必用紫外线EEPROM。微处理器在程序掌握下处理数据，并掌握流向和来自存储器和输入/输出装置的信息流。有些输入/输出装置是通用型