粮库温度检测报警系统本科毕业生外文文献翻译.docx
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粮库温度检测报警系统本科毕业生外文文献翻译
本科毕业生外文文献翻译
学生姓名:
指导教师:
所在学院:
信息技术学院
专业:
电气工程及其自动化
中国·
2012年5月
BasedonSCMmulti-functionaltemperaturetestingsystemdesign
Introduction
Withthedevelopmentofsocietyandthetechnologicalprogress,peoplepaymoreandmoreattentiontotheimportanceoftemperaturedetectionanddisplay.Temperaturedetectionandstatusdisplaytechnologyandequipmenthasbeenwidelyappliedinindustries,productsonthemarketemergeinendlessly.Temperaturetestingandalsograduallyadopttheautomaticcontroltechnologytorealizethemonitor.Thistopicisatemperaturetestingandstatusofthemonitoringsystem.
1Systemsolutions
ThissystemUSESthemonolithicintegratedcircuitAT89S52asthissystem.Thewholesystem,thehardwarecircuitincludingpowersupplycircuit,sensor,thetemperaturedisplaycircuitcircuit,upperalarmcircuit.Thealarmingcircuitcanbemeasuredinuppertemperaturerange,screamingvoicealarm.ThebasicprincipleforthetemperaturecontrolDSl8B20:
whenthetemperaturesignalacquisitiontoaftertemperaturesignalsenttohandle,AT89S52temperaturetoLCDscreen,SCMaccordingtoinitializetheuppertemperaturesetting,namely,ifthejudgementoftemperaturethanthehighesttemperaturecoolingfanisstarted,Ifthetemperatureislessthanthelowesttemperaturesettingonalarmdevice.
2Thesystemhardwaredesign
2.1AT89C51SCMareintroduced
TheAT89S52isalow-power,high-performanceCMOS8-bitmicrocomputerwith4KbytesofFlashProgrammableandErasableReadOnlyMemory(PEROM)and128bytesRAM.ThedeviceismanufacturedusingAtmel’shighdensitynonvolatilememorytechnologyandiscompatiblewiththeindustrystandardMCS-51™instructionsetandpinout.Thechipcombinesaversatile8-bitCPUwithFlashonamonolithicchip,theAtmelat89s52isapowerfulmicrocomputerwhichprovidesahighlyflexibleandcosteffectivesolutiontomanyembeddedcontrolapplications.
PinDescription:
VCCSupplyvoltage.
GNDGround.
Port0
Port0isan8-bitopendrainbidirectionalI/Oport.AsanoutputporteachpincansinkeightTTLinputs.Whenisarewrittentoport0pins,thepinscanbeusedashighimpedanceinputs.
Port0mayalsobeconfiguredtobethemultiplexedloworderaddress/databusduringaccessestoexternalprogramanddatamemory.InthismodeP0hasinternalpullups.
Port0alsoreceivesthecodebytesduringFlashprogramming,andoutputsthecodebytesduringprogramverification.Externalpullupsarerequiredduringprogramverification.
Port1
Port1isan8-bitbidirectionalI/Oportwithinternalpullups.ThePort1outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort1pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port1pinsthatareexternallybeingpulledlowwillsourcecurrentbecauseoftheinternalpullups.
Port1alsoreceivesthelow-orderaddressbytesduringFlashprogrammingandverification.
Port2
Port2isan8-bitbidirectionalI/Oportwithinternalpullups.ThePort2outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort2pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port2pinsthatareexternallybeingpulledlowwillsourcecurrentbecauseoftheinternalpullups.
Port2emitsthehigh-orderaddressbyteduringfetchesfromexternalprogrammemoryandduringaccessestoexternaldatamemorythatuse16-bitaddresses(MOVX@DPTR).Inthisapplicationitusesstronginternalpull-upswhenemitting1s.Duringaccessestoexternaldatamemorythatuse8-bitaddresses(MOVX@RI),Port2emitsthecontentsoftheP2SpecialFunctionRegister.
Port2alsoreceivesthehigh-orderaddressbitsandsomecontrolsignalsduringFlashprogrammingandverification.
Port3
Port3isan8-bitbidirectionalI/Oportwithinternalpullups.ThePort3outputbufferscansink/sourcefourTTLinputs.When1sarewrittentoPort3pinstheyarepulledhighbytheinternalpullupsandcanbeusedasinputs.Asinputs,Port3pinsthatareexternallybeingpulledlowwillsourcecurrentbecauseofthepullups.
Port3alsoservesthefunctionsofvariousspecialfeaturesoftheat89s52aslistedbelow:
Portpin
alternatefunctions
P3.0
rxd(serialinputport)
P3.1
txd(serialoutputport)
P3.2
^int0(externalinterrupt0)
P3.3
^int1(externalinterrupt1)
P3.4
t0(timer0externalinput)
P3.5
t1(timer1externalinput)
P3.6
^WR(externaldatamemorywritestrobe)
P3.7
^rd(externaldatamemoryreadstrobe)
Port3alsoreceivessomecontrolsignalsforFlashprogrammingandverification.
RST
Resetinput.Ahighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetsthedevice.
ALE/PROG
AddressLatchEnableoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory.Thispinisalsotheprogrampulseinput(PROG)duringFlashprogramming.
InnormaloperationALEisemittedataconstantrateof1/6theoscillatorfrequency,andmaybeusedforexternaltimingorclockingpurposes.Note,however,thatoneALEpulseisskippedduringeachaccesstoexternalDataMemory.
Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH.Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction.Otherwise,thepinisweaklypulledhigh.SettingtheALE-disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode.
PSEN
ProgramStoreEnableisthereadstrobetoexternalprogrammemory.
Whentheat89s52isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexternaldatamemory.
EA/VPP
ExternalAccessEnable.EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH.Note,however,thatiflockbit1isprogrammed,EAwillbeinternallylatchedonreset.
EAshouldbestrappedtoVCCforinternalprogramexecutions.
Thispinalsoreceivesthe12-voltprogrammingenablevoltage(VPP)duringFlashprogramming,forpartsthatrequire12-voltVPP.
XTAL1
Inputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingcircuit.
XTAL2
Outputfromtheinvertingoscillatoramplifier.
2.2DS18B20sensor
2.2.1TheintroductionofDS18B20
TheDS18B20DigitalThermometerprovides9to12-bit(configurable)temperaturereadingswhichindicatethetemperatureofthedevice.Informationissentto/fromtheDS18B20overa1-Wireinterface,sothatonlyonewire(andground)needstobeconnectedfromacentralmicroprocessortoaDS18B20.Powerforreading,writing,andperformingtemperatureconversionscanbederivedfromthedatalineitselfwithnoneedforanexternalpowersource.BecauseeachDS18B20containsauniquesiliconserialnumber,multipleDS18B20scanexistonthesame1-Wirebus.Thisallowsforplacingtemperaturesensorsinmanydifferentplaces.ApplicationswherethisfeatureisusefulincludeHVACenvironmentalcontrols,sensingtemperaturesinsidebuildings,equipmentormachinery,andprocessmonitoringandcontrol.
TheDS18B20hasfourmaindatacomponents:
1)64-bitlaserROM,2)temperaturesensor,3)nonvolatiletemperaturealarmtriggersTHandTL,and4)aconfigurationregister.Thedevicederivesitspowerfromthe1-Wirecommunicationlinebystoringenergyonaninternalcapacitorduringperiodsoftimewhenthesignallineishighandcontinuestooperateoffthispowersourceduringthelowtimesofthe1-Wirelineuntilitreturnshightoreplenishtheparasite(capacitor)supply.Asanalternative,theDS18B20mayalsobepoweredfromanexternal3V-5.5Vsupply.
CommunicationtotheDS18B20isviaa1-Wireport.Withthe1-Wireport,thememoryandcontrolfunctionswillnotbeavailablebeforetheROMfunctionprotocolhasbeenestablished.ThemastermustfirstprovideoneoffiveROMfunctioncommands:
1)ReadROM,2)MatchROM,3)SearchROM,4)SkipROM,or5)AlarmSearch.Thesecommandsoperateonthe64-bitlaserROMportionofeachdeviceandcansingleoutaspecificdeviceifmanyarepresentonthe1-Wirelineaswellasindicatetothebusmasterhowmanyandwhattypesofdevicesarepresent.AfteraROMfunctionsequencehasbeensuccessfullyexecuted,thememoryandcontrolfunctionsareaccessibleandthemastermaythenprovideanyoneofthesixmemoryandcontrolfunctioncommands.
TemperaturesensorDS1820memorybyahighspeedbufferpadtypeRAMandanonvolatileelectricallyerasableE2RAMcomposition,thelatterisstoredathightemperatureandlowtemperatureandthetriggerofTHandTL.Scratchpadmemoryhelpsinone-waycommunicationtoensuredataintegrity,dataisfirstwrittentoabuffermemory,whereitcanbereadback.Whendataischecked,copyscratchpadmemorycommandtosendthedatatothenon-volatileE2RAM.Thisprocessensuresthatthechangeofmemorywhilemaintainingdataintegrity.
2.2.2ThecharacteristicsofDSl820
●Theuniquesingleinterfacemode:
DS18B20isconnectedwiththemicroprocessoronlyneedsanexportlinecanrealizemicroprocessorwithDS18B20bidirectionalcommunication.
●Availabledatalinepowersupply,voltagerange:
+3and+5.5V.
●Temperaturerange:
-55to+125degreesc..Intrinsictemperaturemeasurementresolutionof0.5DEGc..
●Supportpointnetworkfunction,multipleDS18B20canbeconnectedinparallelinonlythreeonline,realizethemultipointtemperaturemeasurement
●Negativepressurecharacteristics,powerpolarityreverseconnection,thethermometerisnotduetoheatandburning,butnotnormalWork.
2.3LCD1602LCD
1602LCDmodulecanandmonolithicintegratedcircuitAT89C51directlyinterface.