一個簡單低成本的遙測相對濕度和溫度的數(shù)據(jù)采集系統(tǒng)

ASimpleLowCostDataAcquisitionSystemforRemoteSensingof

RelativeHumidityandTemperatureAbstract：Thispaperpresentsasimpletechniqueincombininganalogcircuitanddigitalcircuittheorytogetherwithprogrammingtechniquetocontrolthehardwareforremotesensingoftemperatureandrelativehumidity.Thesensorcircuitconvertstherelativehumidityandtemperatureintoananalogsignal,whichwillthenbeapplied,toamicrocontrollerbaseddataloggerforstoragepurpose.ThedataisthentransferredtothecomputerthroughRS232standardserialport.Theuserinterfaceprogramwillbehandlingthedatatransferbetweendataloggerandthecomputeraswellasallowingtheusertoinputsomeoftheimportantparameterssuchassamplingintervalandstartingdateandtimefortheloggingoperation.Thesystemcanperforminbothrealtimeandoffline.Keywords：Relativehumidityandtemperature,dataacquisition,remotesensing.1:IntroductionSensingandrecordingbothrelativehumidityandtemperatureplayanimportantroleinmanyindustries.Inpharmaceuticalindustryrelativehumiditycontroliscriticalinmanufacturingofcertainformulationswhicharemoisture-sensitive(hygroscopic)suchasvitamintablets,andoraldehydrationsalttablets.Granulatingandpackagingoperationsofcertaintabletsmustbeconductedinlow-humidityenvironments(maximum25%RHat250c)ifthelong-termstabilityofthetabletsistobemaintained[I].Polishedmetals,e.g.brasses&bronzes,donottarnishat15%relativehumidityorlesswhenkeptinthemuseum[2].Relativehumidityhastobemaintainedatstablelevelstoavoidextremelevelsandwidefluctuations.Ideally,fluctuationsinrelativehumidityshouldnotexceed土3%inonehour,土5%in24hours.Inthepast,someanalogdevicewasusedtorecordtherelativehumidityoveralongperiod.Howeveratpresent,electronicsensinganddataacquisitionprovedtobebetterapproach.ThesensedsignalinanalogformwillbeconvertedtodigitalsignalinordertostoreintheelectronicdevicessuchasEEPROMandRAM.Thesemakethemsmaller,lessexpensiveinlong-termusage,moreaccurateandmorereliablethanchartrecorders.ThestoreddataisthendownloadtoPC.DatainPCformatallowsformoreconvenientdataanalysis,presentationandstorage.Furthermore,itdoesnotrequirecostlyandinconvenientchartsupplybecausedatacanbeviewedonaPCorlaptop.Hardcopy(onlywhennecessary)canbeprintedoutusingtheprinter.VMako[4]hasusedsensitivecapacitivedependentcrystalforHighAirHumiditymeasurment.Thesensorprobeusedisacomblikehumiditysensitiveopencapacitorwhoseoutputisusedtochangethefrequencyofacrystalandthusproducingvariablefrequency.AmicrosystemhasbeendevelopedbyNavidYazdietal.[5]thatutilizesgenericinterfacingwithcapacitivesensorsandthenusedmicrocontrollerbasedwirelesssystemtomeasuretemperaturepressurehumidityacceleration,however,thesystemisquiteexpensiveandcomplexinnature.Techniqueshavealsobeenproposedusingdifferentsensorsystems[6-7]formeasurementofhumidity.Inthispaper,asimpleandeconomicallyfeasibletechniqueformeasuringrelativehumidityandtemperatureisproposed.Thetechniqueuseswidelyavailablecomponentsandwouldbeviableforcommercialuse.2:Topology2.1:TheSensorCircuitAcapacitancerelativehumiditysensorwasusedtosensetherelativehumidity.Thesensorconvertsthiscapacitanceintoavoltageproportionaltorelativehumidity.Forsensingthetemperature,athermistorbridgeisdeveloped.Thesensingcircuithastobeabletoconvertthesensedsignalsinto0-5VvoltagerangetoenabletheADCtoconverttheanalogsignaltodigitalsignal.Alinearoutputisachievedsothatthecircuitiseasytocalibrate.Forthisreason,somelinearizationtechniqueswereused.SensingofRelativeHumidity:Thecapacitorusedinsensingrelativehumidityvariesinvalueswiththechangesofambientrelativehumidity.Thistechniquehasbeenexploitedindevelopingacircuitrythatcandetectthechangesinthecapacitanceduetothechangesoftherelativehumidity.Theobtainedsignalisthenconvertedintoavoltagesignalwithanastablemultivibratorusing555timer.Theoutputsignalsuffersfromsomenon-linearitybecauseofthenon-linearrelationshipbetweencapacitanceandtherelativehumidity.Therefore,thepulseoutputissentthroughaliniearizingnetworkasshowninfig.I.31KR1-VIClllOnF51KFig.1LinearizingcircuitforsensingrelativehumidityThecircuitwillconvertthenonlineaearvoltageV'.WithsuitablechoicesofC1,R1andR2,thesensitivitycanbechanged.Afterlinearizationsomeamplificationisnecessarytoboostthesignallevel.AnLM358OP-AMPisconfiguredasanoninvertingamplifiertodothis.ThesignalisthensenttotheADCthroughaRCfilter.multivibratorusing555timer.Theoutputsignalsuffersfromsomenon-linearitybecauseofthenon-linearrelationshipbetweencapacitanceandtherelativehumidity.Therefore,thepulseoutputissentthroughaliniearizingnetworkasshowninfig.I.31KR1-VIClllOnF51KFig.1LinearizingcircuitforsensingrelativehumidityThecircuitwillconvertthenonlineaearvoltageV'.WithsuitablechoicesofC1,R1andR2,thesensitivitycanbechanged.Afterlinearizationsomeamplificationisnecessarytoboostthesignallevel.AnLM358OP-AMPisconfiguredasanoninvertingamplifiertodothis.ThesignalisthensenttotheADCthroughaRCfilter.SensingofTemperature:ThermistorbridgewithWhetstonearrangementhasbeenusedtodetectthetemperaturechanges.Thebridgewillproduceadifferentialoutputvoltagethatischangedwithtemperaturechanges.Thisvoltageisfeedthroughaliniearizingnetworkasshowninfig.2.R11.8KR3Fig.2LineOyzingnetworkfortemperaTThermistorGp-h1V4ItaV4TprbItif&c51。w仰2530as40455。$5BQ#5707&ad日5Te-np€raiuf-fi-(C-b!±-nri|-Weul—：?” ?■■??二,蛆＜jrFgli|i白I.Fig.3.CharacteristicsoftemperaturesensorTypicalsignalvoltagecharacteristicobtainedfromthelinearizingnetworkisshowninfig.3.2.2:TheDataLoggerThispartisthemainsignal-processingunit.Signalssensedweresenttothedataloggertostoreortransmittothecomputerforfurtheranalysis.Amicrocontrollerisusedforthispurpose.Somesupportivecomponentswerelinkedtothemicrocontrollertoperformtheirspecifictask.Suchasexternalrandomaccessmemory(RAM)waslinkedfordatastorage.Anelectricallyerasableprogrammableread-only-memory(EEPROM)waslinkedtorecordthesamplinginterval,thetimeandsomeimportantinformationneededforthesoftwarecontrol.Ananalogtodigitalconverterisalsolinkedtothemicrocontroller.ThisADCconvertsanyexternalanalogsignalrangedbetween0-5Vtoappropriatedigitalsignalinhexadecimalform.ARS232ICislinkedtothemicrocontrollerforserialcommunicationbetweenthedataloggerandthecomputer.Apropersetofinstructioniswritteninassemblylanguagetooperatethemicrocontrolleranditssupportivecomponents.Fig.4.Blockdiagramofcompletehardware2.3:TheUn-interruptiblePowerSupplyUn-interruptiblepowerssupply(UPS)isanaddedaccessoryforthedatalogger.Thiswillkeepthedataloggerandthesensingcircuittooperateinpowerfailureconditions.TheUPSisconstructedusinganadjustablevoltageregulatorandacomparatortochargethebatterywhileservingtheloads.Thebatteryisalwaysfullychargedwhenthereiselectricity.Ifapowerfailureoccurred,thebatteryautomaticallysuppliesthevoltageneededbythecircuit.2.4:TheSoftwareUser-friendlywindowsbasedsoftwareisdevelopedusingVisualC++.Thesoftwareisusedtodownloadanduploaddatatoandfromthedatalogger.Thedownloadeddatacanbeviewedoranalyzedintableformandgraphform.Thesoftwareisalsoabletoshowtherealtimevaluefromthesensingcircuitforimmediateanalysis.Thedatafilecanbesavedinanopen-fileformatsothatitmayexporttosomecommonspreadsheetprogramsuchMicrosoftExcelforothertypesofillustration.Itofferstheuseralltheessentialfunctionstocontrolaccess,andoptimizingthefeaturesofferedinthehardware.ItisWindow-basedapplicationsoftwarewiththemostpopularWindows95andWindows98GraphicalUserInterface(GUT).Thesoftwareimplementationcanbecategorizedintothreeparts;firstpart中北大學2013屆英文文獻原文及中文翻譯consistsofimplementationofthedatapresentationthatcanbeintableformatoringraphformat.Secondpartistheprogrammingforrealtimeoperationwiththedataloggerandthefinalpartisthedownloadinganduploadingprocesswiththedatalogger.Besidesthesethreemainparts,thereareseveralfunctionsconstructedfortheprogramsuchasprintinginhardcopy,convertingthedatafiletotextfileformatandcalibrationtechnique.3:TestResultsAfewexperimentswerecarriedouttotesttheaccuracyofrelativehumidityandtemperaturemeasurement.Besidesthat,thetimingaccuracyofthemicrocontrollerhasalsobeentested.TheseexperimentsweredoneafterthemachinecodehasbeenprogrammedintotheinternalROMofthemicrocontrollertoavoidlocalheatingfromthein-circuitemulator.SensorAccuracyTest:Afewexperimentswereconductedindifferentrangeoftherelativehumidity.Itisdifficulttoobtainanenvironmentwithdifferentrelativehumidity.Therefore,relativehumidityhasbeenmeasuredatdifferentenvironmentalconditions,suchasbeforeandafterrain,sunnyafternoonandcoldmorning.etc.Finally,arangefrom40%to85%relativehumiditywasobtainedafterafewexperimentscarriedoutwithinaweek.TheresultsobtainedfromtheSlingPsychrometer(SP)andData2000(proposedsystem)aresummarizedinTable1.ThetemperatureshowninthedrybulboftheSlingPsychrometerisrecordedaswelltocomparetheTemperaturereadingfromData2000.FromtheresultsshowninTable1,itisobservedthattherelativehumiditysensorshowsagreatstabilityandaccuracy.Themaximumerrorisonly3.25%.Thisdiscrepancyisbecauseofthe土0.5LSBerrorintroducedbytheADC.However,theerrorisrathersmallcomparedtotheinitialinaccuracyof3%atthesensingcircuitry.Therelativehumidityrangebelow40%isnottestedbecausethecorrespondingenvironmentalconditionishardtoobtain.Theaccuracyofthetemperatureisslightlylow.Anaverageerrorof10cisobserved.Thesamereasonstandsherethatanerrorof土0.390cfromtheADCwasintroducedtothe土0.50cerroratthesensingcircuitry.Besides,thetemperaturesensorislessstablecomparedtotherelativehumiditysensor.Thtsmightthecauseofhighdegreeofthesensitivityofthesensorasthesurroundingeasilyinfluencesitsoutput.Thefullrangeoftemperatureisnottestedwith,asoutputfromthetemperaturesensingcircuitisfoundlinear.TheADConlyintroducedaconstanterrorof0.390ctotheoutput.Tablel.TestresultsobtainedusingData2000andSPSlingPsychrometer(SP)Data2000DifferenceTemp(0c)RH(%)Temp(0c)RH(%)Temp(0c)RH(%)32.54231.2341.311.270.6932.04535.5446.58-3.54-1.5831.55031.2351.360.27-1.3631.55330.8354.710.67-1.7130.56132.4059.01-1.901.9930.55931.2359.49-0.73-0.4928.07827.3078.630.70-0.634:ComparisonAcomparativestudyhasbeencarriedoutwithafewindustrialstandardrelativehumidityandtemperaturemeasuringdevicesthatareavailableinthemarket.TheresultissummarizedinTable3.Ananalogdatarecorder(Temperature/Humidity/DewpointRecorderfromSUPCO)isincludedinordertocomparetheadvantagesofdigitaldatalogger.Table2.ComparativeanalysisofdifferentfeaturesofData2000CompanyNameSUPCOACRVeriteq[15]DelataTRAK[16]ProposeddeviceProductNameTemp/RH/DewpointRecorderMiniDataLoggerSpectrum2000FlashLinkData2000TypeAnalogDigitalDigitalDigitalDigital

Built-inSensorTemperatureAccuracy土2%土0.25oC+0.5oC±1.0oC(0-55oC)TemperatureRange(0C)-30to50-40to85-40to660to85R.H.Accuracy土2%土2%土5%±3%(50-75%)±5%(otherwise)R.H.Range(%)0to1000to9510-10010to90DataLoggingMemoryTypeChartpaperEEPROMRAMMemoryCapacity7Days(max)8K32K10K64KResolution8bit12bit8bitMemoryModesRotationFirstinfirstoutFirstinfirstout/StopwhenmemoryfullStop whenmemoryfullMemoryProtectionChartpapercanbekeptforlongtimeDataretention20yearswithoutpowerNoMinimumSamplingRatesFixat2minutes10seconds3seconds1secondMaximumSamplingRates24hours24hours1hourUser-selectableSamplingRatesYesNoYesYesYesRecordingSpanwithselectedsamplingrate1secondChartselectablelastfor1.5hoursto7days2.8days(samplingratefixed)NoNo18.2hours10second30hours13.8hours91hours1minute7.4days3.4days22.7days15minute3.7month1.7month11month1hour1.2yearsNo7.5yearsProgrammableDelayedStartNo0secondsto256days1secondto18hoursBackupPower8xAAalkalinebattery5 yearsInternallithiumbattery10yearsInternallithiumbattery1yearlife3.0voltlithium13hoursto3days)based Onbattelycapacity(userselectable)Price(USD)Hardware900200400100SoftwareFree100ChargeFreeTotal938200500100ItisobservedfromthetablethatData2000hasextralargememorycapacitythatallowstheusertorecorddatamorefrequentlyforalongtime.Forexample,iftheuserneedstomonitortheenvironmentofaroomfor3days,heorshecansetthesamplingintervalequalto10secondsprovidedhehas64Kb.ytesofdatamemory.Orhemightsetthesamplingintervalat2minutes,ifitisusedwithonly8Kbytesofdatamemory.Themostimportantfeatureofthisdeviceisitscost.ThecostofData2000canbeconsideredverycheapcomparedtootherdataloggersinthesameclass.Itspriceisevencheaperthanthelow-endMiniDataLogger.Analogrecorderwhichistotallyoutofcompetitionasitisbulky,limitedfunctionandexpensive.Data2000canalsoprovidethefacilitiesforremotesensinglikeas,i)Delayedstart,ii)Userselectabledatasamplingrateiii)S-bitdigitalresolution,iv)Softwarecontrolsupport.Themaindrawbackofthisdeviceisitshighpowerconsumption.ThisweaknessisapprehendedearlierwhenthedesignwasperformedusingordinarystandardICS.However,almostallcomponentsusedinotherdigitaldataloggeraresmalloutlineIC(SOICpackage),withlowpowerconsumptionandmayhavesleepmodefunctionwhileitisnotinoperation.Nevertheless,thislimitationisnotthatcriticalwhenconsideringtheofferedadvantagesandsinceitispoweredbytheelectricsupplyatnormalsituationorUPSduringthepowerfailure.ThesensingcircuitforData2000offeredtherangeandaccuracyclosetotheindustrystandard.Anaccuracyof土1°cfortemperatureand土3%forrelativehumidityisreasonable.Theshortcomingofthesensingcircuitisthatitdoesnothavetheabilitytooperateatatemperaturebelow0。candatarelativelylowhumidatmosphere.5.ConclusionArelativehumidityandtemperaturemeasurementinstrumentcumdataloggerwithbuilt-insensingcircuitryhasbeensuccessfullydevelopedandconstructed.Itisalow-costproductbutwithessentialfeaturesthatallowremotesensing.Itishopedthatthedevicewill中北大學2013屆英文文獻原文及中文翻譯haveahighcommercialvalue.Itslargememorycapacityofferstheuserahighresolutionbasedonitshighsamplingrateindataacquisition.Thisisanaddedadvantagecomparedtotheotherdataloggersofthesameclass.Theoverallsystemhardware,particularlythefront-endsensingcircuit,hasperformedwell.Theattemptoflinearizingtheanalogoutputhasshownsignificantimprovementinobtainingaccuratedata.Thisalsoresultsinaneasysoftwarecalibrationknownas"twopointcalibration".Thesoftwarehasalsobeenfurnishedwithalltheessentialfunctions.Acknowledgement:PreliminaryresultsofthispaperwaspresentedatTENCON2000,KualaLumpur,Malaysia.References[I]PharmaceuticalDosageForm:TabletVolume1,EditedbyHerbertA.Lieberman,SecondEdition,MarcelDekker,Inc.,pp-310⑵PreventiveConservation,byFergusRead,NorthWestMuseumsService,1994.;/preventa.htmPhilipsElectronicComponentsandMaterials,TechnicalNote134,RevisedEdition;33.V.Matko,"SensorforHigh-Air-Humiditymeasurement",IEEEtransactionsonInstrumentationandMeasurements,Vol.45.No.2,pp.561-564.NavidYazdieta/,"ASmartSensingMicrosystemWithaCapacitiveInterface",IEEEconferenceproceeding,1996pp.336-339.T.J.Harpsteretal.,"APassiveWirelessIntegratedHumiditySensor",IEEEconferenceproceeding,2001,pp.553-557.D.H.Leeetal.,"AMicromachinedRobustHumiditySensorforHarshEnvironmentApplications",IEEEconferenceproceeding,2001,pp.558-56.一個簡單低成本的遙測相對濕度和溫度的數(shù)據(jù)采集系統(tǒng)摘要：本文提出一種在結合模擬電路和數(shù)字電路理論以及編程技術去控制硬件遙測溫度和相對濕度的技術。這個傳感器電路將相對濕度和溫度轉換成一個可以應用的模擬信號，基于數(shù)據(jù)記錄器的微控制器用于存儲。然后數(shù)據(jù)通過RS232標準串行端口傳輸?shù)接嬎銠C。用戶界面程序可以執(zhí)行數(shù)據(jù)記錄器和計算機之間的數(shù)據(jù)傳輸以及允許用戶輸入一些重要參數(shù)，諸如采樣間隔、開始日期和記錄操作的時間。該系統(tǒng)在在線狀態(tài)和離線狀態(tài)都可以執(zhí)行。關鍵詞：相對濕度和溫度，數(shù)據(jù)采集，遙感。1：簡介相對濕度和溫度的感測和記錄在許多行業(yè)中起著重要的作用。在制藥行業(yè)中相對濕度的控制在某些易潮濕的配方的生產(chǎn)中是相當嚴格的，諸如維生素藥片和口服脫水鹽藥片。如果藥片要長期保持穩(wěn)定，那么某些藥片的造粒和包裝操作必須在低濕度（在25°C下最大為25%RH）的環(huán)境下進行［1］。拋光的金屬，如銅管樂器和青銅制品，當在博物館里保存時，相對濕度為15%或小于15%時，就不會失去光澤［2］。相對濕度必須維持在穩(wěn)定的水平，避免極端水平和大范圍的波動。理想情況下，相對濕度的波動在一個小時內不應超過土3%，在24個小時內不應超過土5%。在過去很長一段時間內，相對濕度用一些模擬裝置來記錄。然而目前，電子感測和數(shù)據(jù)采集被證明是更好的的方法。為了存儲在諸如EEPROM和RAM的電子元件中，模擬形式的感測信號將被轉換成數(shù)字信號。這比圖表記錄使用的器件更小，在長期使用時更廉價，更加精確、可靠。然后存儲的數(shù)據(jù)下載到個人電腦。在個人電腦中的數(shù)據(jù)格式更加方便數(shù)據(jù)分析、描述和存儲。此外，數(shù)據(jù)可以在個人電腦或筆記本電腦上顯示，因此它不需要昂貴和復雜的圖表供應。硬拷貝（僅在必要時）可以使用打印機打印出來。VMako［4］利用晶體制作的敏感電容測量高空大氣濕度。傳感器探頭像濕度敏感電容的梳子，它的輸出是用來改變晶體的頻率，因此產(chǎn)生可變的頻率。NavidYazdi［5］已經(jīng)開發(fā)了一個微系統(tǒng)，這個系統(tǒng)利用通用的接口與電容傳感器連接，然后使用基于無線系統(tǒng)的單片機來測量溫度壓力濕度加速度，然而，這個系統(tǒng)在本質上是非常昂貴和復雜

的。運用不同的傳感器系統(tǒng)［6—7］測量濕度的技術已經(jīng)被提出來了。本文提出一個測量相對濕度和溫度的簡單和經(jīng)濟可行的技術。這項技術使用普遍可用的器件，對商業(yè)用途是可行的。2：構成:傳感器電路電容相對濕度傳感器用來感測相對濕度。該傳感器將電容轉換成與相對濕度成比例的電壓。對于溫度傳感器，熱敏電阻橋式電路已經(jīng)提出來了。這個感測電路必須能夠把感測信號轉換成可以用ADC轉換器把模擬信號轉換成數(shù)字信號的0-5V范圍的電壓。線性輸出的電路很容易調整。由于這個原因，一些線性化技術得到應用。相對濕度的感測：電容器應用于感測周圍環(huán)境的相對濕度的變化引起的相對濕度變化值。這種技術已經(jīng)應用于檢測由于相對濕度的變化引起的電容值的變化的電路。然后使用555定時器的非穩(wěn)態(tài)多諧振蕩器可以把獲取的信號轉換為電壓信號。由于電容和相對濕度的非線性關系，因此輸出信號具有一定的非線性。因此，通過線性網(wǎng)絡脈沖輸出得到發(fā)送，如圖1所示。VI31KR1-WvVIClLR2llOnF?51K圖1感測相對濕度的線性電路這個電路將非線性輸出電壓轉換成線性電壓。選擇合適的C1，R1和R2,可以改變靈敏度。為了提高信號電平，線性放大是必要的。配置同相運算放大器LM358OP-AMP來完成信號的放大。然后信號通過RC濾波器送到ADC轉換器。

溫度感測：用惠斯登熱敏電阻橋檢測溫度的變化。電橋由于溫度的變化將要產(chǎn)生一個可以改變的微小的電壓輸出。電壓通過線性網(wǎng)絡輸出，如圖2所示。R1.8KR3R2R38K7K8K圖2溫度傳感器的線性網(wǎng)絡圖3溫度傳感器的特性圖2溫度傳感器的線性網(wǎng)絡圖3溫度傳感器的特性線性化網(wǎng)絡獲取的典型電壓信號特性如圖3所示。:數(shù)據(jù)記錄器這部分是主要的信號處理單元。感測信號被送到數(shù)據(jù)記錄器存儲或傳輸給計算機進行進一步的分析。微控制器就是應用于這個目的。微控制器的一些支持組件執(zhí)行特定的任務。如外部隨機存取存儲器(RAM)用于數(shù)據(jù)的存儲。電可擦除可編程序只讀存儲器(EEPROM)用于記錄抽樣間隔、時間和軟件控制需要一些重要的信息。模擬數(shù)字轉換器也

要用到微控制器。任何范圍在0-5V的外部模擬信號的ADC轉換都可以用適當?shù)氖M制形式的數(shù)字信號表示。微控制器的RS232格式用于數(shù)據(jù)記錄器和電腦的串行通信。用匯編語言編寫的適當?shù)慕M指令操作微控制器和它的支持組件。圖4完整的硬件框圖:不間斷電源不間斷電源(UPS)是數(shù)據(jù)記錄器的附加功能。這保證在電源故障的情況下數(shù)據(jù)記錄器和感測電路的運行。使用可調電壓調節(jié)器和比較器構建的UPS在加載服務時給電池充電。當有電時，電池總是處于完全充電。如果電源發(fā)生故障，電池自動提供電路需要的電壓。2.4:軟件基于windows使用VisualC++軟件開發(fā)很人性化。這個軟件通常是從數(shù)據(jù)記錄器上下載和上傳數(shù)據(jù)。下載的數(shù)據(jù)可以用表格形式和圖表形式查看。這個軟件從對感測電路的實時分析也顯示出實時的價值。數(shù)據(jù)文件可以在打開的文件格式中保存，因此可以輸出一些常見的電子表格，如Excel等其它類型的圖解。它提供了用戶控制訪問和優(yōu)化硬件功能的所有必需的函數(shù)。最受歡迎的Windows95和Windows98圖形用戶界面(GUI)是基于窗口的應用軟件。軟件實現(xiàn)可分為三個部分。第一個部分包括數(shù)據(jù)表示的實現(xiàn)，可以用表格形式或圖表形式實現(xiàn)；第二部分是編程對數(shù)據(jù)記錄器的實時操作；最后一部分是用數(shù)據(jù)記錄器下載和上傳數(shù)據(jù)的過程。除了這三個主要部分，還可以編程實現(xiàn)一些功能，如用硬拷貝打印、把數(shù)據(jù)文件轉換為文本文件格式和校準技術。

3:測試結果實施一些實驗來測試相對濕度和溫度測量的精度。除此之外，微控制器的定時精度也已經(jīng)被測試。為了避免內部電路仿真器的局部發(fā)熱，這些實驗要在機器代碼已經(jīng)編程寫入微控制器的內部ROM之后進行。傳感器精度測試：幾個實驗在不同的相對濕度下實施。這非常難獲取到相同環(huán)境下的不同的相對濕度。因此，相對濕度的測量要在不同環(huán)境狀態(tài)下進行，如在下雨之前與之后、陽光明媚的下午和寒冷的早晨等等。最后，40%到85%的相對濕度要在同一個星期進行多次試驗獲取。用懸掛式濕度計（SP）和數(shù)據(jù)2000（參考系統(tǒng)）獲取的結果如表1。記錄懸掛式濕度計的干球顯示的溫度與數(shù)據(jù)2000讀取的溫度作對比。從表1顯示的結果來看，可以看出相對濕度傳感器顯示了明顯的穩(wěn)定性與精度。最大誤差僅為3.25%。這個差異是由于ADC轉換器引入的土0.5LSB的誤差。然而，與傳感器電路的初始誤差3%比起來，這個誤差還是相當小的。相對濕度范圍在40%以下的沒有測試，因為相應的環(huán)境條件是很難獲取的。這個溫度的精度略低。觀察到的平均誤差是1°C。同樣的理由仍然適合，ADC轉換器引入的土0.39°C的誤差對比傳感器電路的土0.5°C的誤差。此外，與相對濕度傳感器相比，溫度傳感器較為不穩(wěn)定。這可能是高靈敏的傳感器周圍環(huán)境隨容易影響其輸出的原因。由于溫度傳感電路的輸出是線性的，因此完整范圍的溫度是不能被測試的。對于輸出ADC轉換器僅僅引入了一個土0.39°C常量誤差。表1.使用數(shù)據(jù)2000與SP獲取的測試結果懸掛式濕度計（SP）數(shù)據(jù)2000變化溫度（0C）RH(%)溫度（0C）RH(%)溫度（0C）RH(%)32.54231.2341.311.270.6932.04535.5446.58-3.54-1.5831.55031.2351.360.27-1.3631.55330.8354.710.67-1.7130.56132.4059.01-1.901.9930.55931.2359.49-0.73-0.4928.07827.3078.630.70-0.63

4:對比用市場上可利用的一些工業(yè)標準的相對濕度和溫度測量設備的對比研究已經(jīng)實施?？偨Y結果如表2。為了對比數(shù)字數(shù)據(jù)記錄器的優(yōu)勢，因此包括了模擬數(shù)據(jù)記錄器（溫度/濕度/來自SUPCO的節(jié)點記錄器）。表2.數(shù)據(jù)2000不同特點的參數(shù)分析公司名稱SUPCOACRVeriteq[15]DelataTRAK[16]參考設備產(chǎn)品名稱溫度/RH/節(jié)點記錄器小型數(shù)據(jù)記錄右器光譜2000FlashLink數(shù)據(jù)2000類型模擬數(shù)字數(shù)字數(shù)字數(shù)字內置傳感器溫度精度土2%土0.25oC土0.5oC土1.0oC（0-55oC）溫度范圍（0C）-30至50-40至85-40至70-40至660至85RH精度土2%土2%土5%土3%（50-75%）土5%（其它）RH范圍（%）0至1000至9510-10010至90數(shù)據(jù)記錄器儲存器類型圖標紙EEPROMRAM儲存器容量7天（最大）8K32K10K64K分辨率8位12位8位儲存器模式循環(huán)先進先出先進先出/儲存器存滿時停止儲存器存滿時停止儲存器保存時間圖表可以保存很長時間沒有電時數(shù)據(jù)可以保存20年否最小采樣速率固定為2分鐘10秒3秒1秒最大采樣速率24小時24小時1小時用戶可選擇采樣速率是否是是是

記錄不同跨度的采樣率1秒圖標可選擇持續(xù)1.5小時至7天2.8天（固定的采樣速率）否否18.2小時10秒30小時13.8小時91小時1分鐘7.4天3.4天22.7天15分鐘3.7月1.7月11月1小時1.2年否7.5年延遲開始可編程否0秒至256天1秒至18小時備用電源8xAA堿性電池內配5年鋰電池內配10年鋰電池配1年3.0V鋰電池依據(jù)電池容量13小時至3天（用戶自己選擇）價格(USD)硬件900200400100軟件38免費100收費免費總共938200500100從表格可以看出數(shù)據(jù)2000擁有允許用戶在長時間內更頻繁的記錄數(shù)據(jù)的大的額外存儲容量。例如，如果用戶需要監(jiān)測一個房間環(huán)境3天，他或她可以設置10秒的采樣間隔，只要有64K的數(shù)據(jù)存儲器就行了?；蛘咚蛟S設置2分鐘的采樣間隔，只要有8K的數(shù)據(jù)存儲器就行了。這種設備最重要的特點是其成本。數(shù)據(jù)2000的成本比其他同類數(shù)據(jù)記錄器廉價。它的價格甚至比低端小型數(shù)據(jù)記錄器更便宜。由于模擬記錄器笨重、功能有限、昂貴，因此它完全沒有競爭力。數(shù)據(jù)2000也可以提供遙測的設施，如（1）延遲開始，（2）用戶選擇數(shù)據(jù)采樣率，（3）8位的數(shù)字分辨率，（4）支持軟件控制。本裝置的主要缺點是它的消耗功率高。當這個設計用普通標準ICS實施時，這個弱點就已經(jīng)被發(fā)現(xiàn)了。然而，用于其它的數(shù)據(jù)記錄器的幾乎所有的組件都是小外形的集成電路（SOIC封裝），在沒有工作時處于低功率消耗和睡眠模式。雖然如此，考慮到提供優(yōu)勢及正常情況下有電力供應即使出現(xiàn)電源故障也可以使用UPS時，這種限制不是主要的。數(shù)據(jù)2000的感測電路提供的范圍和精度接近工業(yè)標準。溫度精度為土1°C和相對濕度精度為土3%是合理的。感測電路的缺點是在低于0°C和相對低的潮濕空氣下不能運行。5.結論附帶內置感測電路的數(shù)據(jù)記錄器的相對濕度和溫度測量儀器已經(jīng)成功開發(fā)和構建。

這是一個低成本但是有允許遙感的基本特性的產(chǎn)品。該設備有望擁有高的商業(yè)價值。在數(shù)據(jù)采集中高采樣率的基礎上，大的存儲容量為用戶提供高的分辨率。與其它同類的數(shù)據(jù)記錄器相比，這也是一個額外的優(yōu)勢。整個硬件系統(tǒng)，尤其是前端感測電路，運行良好。獲取精確數(shù)據(jù)時，線性化的模擬輸出顯示顯著改善。這也引出了稱為“兩個點校準”的簡單的軟件校準。該軟件還提供了所有必要的功能。致謝本文的初步結果發(fā)表在TENCON，2000年，馬來西亞吉隆坡。參考文獻制藥劑量的組成：藥片體積1，赫伯特，馬塞爾?德克爾，頁310.預防性保護，費格斯讀，西北博物館，1994./preventa.htm飛利浦電子元件和設備，技術說明134，修訂版；頁17-33.V.Matko,“高空大氣濕度測量的傳感器”，儀器和測量IEEE會議，第二卷45；頁561-564.NavidYazdi，"電容式接口的智能傳感微系統(tǒng)”，IEEE會議論文，1996,頁336-339.t-j-Harpster，"無源的無線集成濕度傳感器”，IEEE會議論文，2001，頁553-557.D?H?Lee，"惡劣環(huán)境中微型機械濕度傳感器的應用”，IEEE會議論文，2001，頁558-561.DistributedTemperatureandHumidityAcquisitionSystemBasedonIA4421Abstract-Nurseryshedshavethecharacteristicsofstayingclosely,quantity,parameterchangingslowly,asmallamountofdata,sothearticlepresentsadistributedcentralizedmonitoringsystembasedonashort-rangeradiotransceiverIA4421chip.Thefront-endsystemcircuitchoosesingle-chipSTC89LE52RCasthecontrolofthecore,completeahumiditysensorHSl101,thetemperaturesensorDS18B20circuitandIA4421peripheralcircuitdesign,methodofCRC,aftercompletingfront-endsystemsandhardwaredesignofdatacenter,designgivesthesoftwaredesign,thecorrespondingflowchartandsomeinstances.KeyWords-IA4421；DS18B20;HSllOl;CRC;wirelesstransmission;distributedINTRODUCTIONTheshort-rangewirelesstransmissiontechnologycangetmorethanonenurseryshedparametersoftemperatureandhumidityandpooledcentralizedmonitoring,thistypeofscenetemperatureandhumidityparameterschangesslowly,ittakesmoreintervaltimeindataacquisition,andtheamountofdatavalueforeachsampleissmall;fromatechnicalperspective,withthemonitoringsystemofthistypewithmanymonitoringpoints,itismoresuitabletousetheadvancedzigbeewirelessnetwork.However,examinefromaneconomicpointofview,suchprogramsaretoomuchexpensive.InthispaperaprogramcameupwithadistributedcentralizedmonitoringbasedonthewirelesschipIA4421,theprogramissuitablefortheabove-mentionedtypeofscene,andithasobviousadvantagesincost.SYSTEMANDHARDWAREDESIGNA.SystemcomponentsWithtoomanydistributedmulti-monitoringpointswhichthedistanceisshort(d<100m)anddistribution,systemdecidetoadoptashort-rangewirelesscommunication

chiptoformadistributedwirelessmonitoringsystem,showninFigure1.Therearemfront-endmonitorsandawirelessmonitoringsystemcenter,eachfront-endmonitorhasamicrocontrollercore,collectedbythetemperatureandhumiditysensorstogettemperatureandhumidityparameters,themicrocontrollersendtheparameterstothewirelessmonitoringcenterthroughfront-endwirelesscommunicationschips.FrontendmonitormFront-endmonitor?_丫二Front-endmonitorlMCUIA4421r>MonitoringcenterFront-endmonitor3Front-endmonitor?_丫二Front-endmonitorlMCUIA4421r>MonitoringcenterSENSORS:MCU:? IIA4421Figure1.DistributedwirelessacquisitionsystemWirelessmonitoringcenteristhecenterofthewholesystem,ithastakentothepollingwork,andgiveinstructionswhichwereissuedtothevariousfront-endmonitoringunits,thefront-endmonitoringunitsonlyreceiveditsownpollingcommandandthendecidedtolaunchoutoftheunitdata.Thesystemisdesignedevery3secondspollingprogram,everyminutecanbepolledto20monitoringunitsanditisbettertoextendthepollingcycleordecreasethepollmgintervaltosolvethelarger-scalemonitoringsite.B.Front-endmonitoringunitsFront-endmonitoringunitisresponsibleforthecollectionsiteofthetemperatureandhumidityparameters,andsendthecollectedtothewirelessmonitoringcenter,thecircuitschematicshowninFigure2.DesignusesSTC89LE52RCasthecontrollercore,thecontrollerhastheadvantageofdownloading

theprogramthroughserialport.Theinstructionsandthecodesarefullycompatiblewiththe51MCUwithinsixinterruptsources,fourmterruptprioritylevels,awatchdogtimer(WDT),theclockfrequencyupto40MHz[1].ThesystemissuppliedwithDC6V,using3.3VvoltageregulatorchipASM1117-3.3tosupplymicrocontrollerandwirelesschip.Dallascompany'sI-WirebusdigitaltemperaturesensorDS18B20isusedintemperaturemeasurementcircuit.Thedesignusesa3-pinTO-92small-sizepackage,thetemperaturemeasurementrangeof-55to125°C,programmablefor9-12bitA/Dconversionandtheprecisiontemperatureresolutionupto0.0625°C,Thedigitalformatoftemperaturewithconvertedof12bittakesthemaximumtimeof750ms[2].Thedesignuses9bitdigitalformat,thedefaultconversionaccuracyis0.5°C,theconversiontimeisabout100ms[3].*JJVDS18B2D-GNDNIE、VSS-FFFTriREiCLKXTL-IA4421T.圳伽SH~iiiSll—WW—uS|：lVDD*JJVDS18B2D-GNDNIE、VSS-FFFTriREiCLKXTL-IA4421T.圳伽SH~iiiSll—WW—uS|：lVDD—KEMiltQRl珈FSTCB^LEJJRCAWill?WU￥IN VQ4JTJ1C610uFIf+3.3V3plFigure2.Circuitoffront-endmonitoringunitsHumidityacquisitionuseshumiditysensorHS1101andNE555inthecircuit,HS1101canaffecttheoscillationfrequencyoftheNE555circuitwhentheoutsidehumiditychangesandthecapacitorvalueofbothendoftheHS1101ischanged,therebychangingtheoutputfrequencyofthetimingcircuit.TheMCUsystemcalculatethehumidityfieldthroughthemeasurementofthefrequen