基于IA4421分布式溫度和濕度采集系統(tǒng)(英語原文與翻譯)

..DistributedTemperatureandHumidityAcquisitionSystemBasedonIA4421Abstract-Nurseryshedshavethecharacteristicsofstayingclosely,quantity,parameterchangingslowly,asmallamountofdata,sothearticlepresentsadistributedcentralizedmonitoringsystembasedonashort-rangeradiotransceiverIA4421chip.Thefront-endsystemcircuitchoosesingle-chipSTC89LE52RCasthecontrolofthecore,completeahumiditysensorHSl101,thetemperaturesensorDS18B20circuitandIA4421peripheralcircuitdesign,methodofCRC,aftercompletingfront-endsystemsandhardwaredesignofdatacenter,designgivesthesoftwaredesign,thecorrespondingflowchartandsomeinstances.Keywords-IA4421;DS18B20;HSllOl;CRC;wirelesstransmission;distributedI.INTRODUCTIONTheshort-rangewirelesstransmissiontechnologycangetmorethanonenurseryshedparametersoftemperatureandhumidityandpooledcentralizedmonitoring,thistypeofscenetemperatureandhumidityparameterschangesslowly,ittakesmoreintervaltimeindataacquisition,andtheamountofdatavalueforeachsampleissmall;fromatechnicalperspective,withthemonitoringsystemofthistypewithmanymonitoringpoints,itismoresuitabletousetheadvancedzigbeewirelessnetwork.However,examinefromaneconomicpointofview,suchprogramsaretoomuchexpensive.InthispaperaprogramcameupwithadistributedcentralizedmonitoringbasedonthewirelesschipIA4421,theprogramissuitablefortheabove-mentionedtypeofscene,andithasobviousadvantagesincost.II.SYSTEMANDHARDWAREDESIGNA.SystemcomponentsWithtoomanydistributedmulti-monitoringpointswhichthedistanceisshort<d<100m>anddistribution,systemdecidetoadoptashort-rangewirelesscommunicationchiptoformadistributedwirelessmonitoringsystem,showninFigure1.Therearemfront-endmonitorsandawirelessmonitoringsystemcenter,eachfront-endmonitorhasamicrocontrollercore,collectedbythetemperatureandhumiditysensorstogettemperatureandhumidityparameters,themicrocontrollersendtheparameterstothewirelessmonitoringcenterthroughfront-endwirelesscommunicationschips.Figure1.DistributedwirelessacquisitionsystemWirelessmonitoringcenteristhecenterofthewholesystem,ithastakentothepollingwork,andgiveinstructionswhichwereissuedtothevariousfront-endmonitoringunits,thefront-endmonitoringunitsonlyreceiveditsownpollingcommandandthendecidedtolaunchoutoftheunitdata.Thesystemisdesignedevery3secondspollingprogram,everyminutecanbepolledto20monitoringunitsanditisbettertoextendthepollingcycleordecreasethepollmgintervaltosolvethelarger-scalemonitoringsite.B.Front-endmonitoringunitsFront-endmonitoringunitisresponsibleforthecollectionsiteofthetemperatureandhumidityparameters,andsendthecollectedtothewirelessmonitoringcenter,thecircuitschematicshowninFigure2.DesignusesSTC89LE52RCasthecontrollercore,thecontrollerhastheadvantageofdownloadingtheprogramthroughserialport.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].Figure2.Circuitoffront-endmonitoringunitsHumidityacquisitionuseshumiditysensorHS1101andNE555inthecircuit,HS1101canaffecttheoscillationfrequencyoftheNE555circuitwhentheoutsidehumiditychangesandthecapacitorvalueofbothendoftheHS1101ischanged,therebychangingtheoutputfrequencyofthetimingcircuit.TheMCUsystemcalculatethehumidityfieldthroughthemeasurementofthefrequencyofitsoutput.Thesitehumidityandtheoutputfrequencycorrespondingrelationship[4]isshowninTable1.TABLEIHUMIDITYANDTHEOUTPUTFREQUENCYCORRESPONDINGRELATIONSHIPRF102030405060708090Fr722471006976685367286600646863306186C.WirelesstransceiverportionandthewirelessmonitoringcentercircuitIntegrationAssociatesproductionofshort-rangewirelesstransceiverchipIA4421isusedinthisdesign.Thisisafullyintegrated,lowpowerconsumptionandrequiresveryfewexternalcomponents,multi-channel,programmable,low-cost,high-performancewirelesscommunicationschip[5].ChiphasaprogrammablePLLfrequencysynthesizerwithhigh-precision,andthesendingletterfrequencyoffsetandreceiverbandwidthisalsoprogrammable,ithasgreatflexibilityinapplications.ThechipusesFSKmodulationmode,theoperatingbandisoptionalforthe433M,868Mand915M,thelargestsendingletterpowerupto8dBm,whenthereceiversensitivityis-109dBmandthebiterrorrateis10-3,theairrateupto115.2kbpS,sendinglettercurrentlessthan24mA,receivingcurrentislessthan10mA.standbycurrentisonly0.3uAthemaximumcommunicationdistanceis100metersto200meters[6].InadditiontothecrystaloscillatorandtheantennatheIA4421peripheralcircuithasonlytwoinductorsandtwocapacitors,andtheirspecificparametersdependonthesystemofcommunicationfrequencyselecting.ThespecificparametersshowninTable2.OtherconnectionwiththeMCUpinnamesareshowninTable3,pin8ofIA4421outputsclocksignal,thereisnouse.WhenIA4421chipisintransmittingmode,theNFFSpinoftheMCUissettinghigh,thenthemicrocontrollersendsinitializationcommandstothetransmittertosetinitializationsettings,whichsetthepreambleofAAH,synchronousformatissettingof2004,thebaudrateis9600bps,theoperatingfrequencyis915MHz,andthensendthecommand8238Htotumonthetransmitter.PinnSELsetslowwhensendingdata,andthenwritedatathroughtheSDI,eachclockcyclewriteonebit.WhenreadingoutthestatusflagbitSDOis1,thatmeanstransmitterhassentabyte,themicrocontrollerwillwritethenextbyteofdata.Whenthechipisinreceivingmode,theNFFSpinissettinglow,theoutputbufferofFIFOconnecteddirectlytotheSDOpin.Setofsynchronousformat,baudrate,operatingfrequencywiththetransmitmode.TheIA4421hasaninternal16RXdataFIFOandreceiverhasFFITreceivinginterrupt,whenthereceiveddatabitsreachesapresetnumber,FFITpinoutputshighlevel,andinstructthemicrocontrollertoreadoutthedatafromtheSDOpin.Wirelessmonitoringofthecentralpartofthecircuitusingthesamemicroprocessorandwirelesstransceiverchipasthefront-endmonitoringunit,RS232interfacecircuitisincreasedinthiscircuit.TABLEIIIA4421CIRCUITPARAMETERSANDFREQUENCYFreq〔MHzC6、C7〔pFL2〔nHL1<nH4334.72739086836.810091536.8100TABLE3IA4421PINSPinNameTypeFunctionPin1SDIDIDatainputoftheserialcontrolinterfacePin2SCKDIClockinputoftheserialcontrolinterfacePin3nSELDIChipselectinputoftheserialcontrolinterface<activelow>Pin4SDODOSerialdataoutputwithbusholdPin5NIRQDOInterruptrequestoutput<activelow>Pin6NFFSDIFIFOselectinput<activelowPin7FFITDOFIFOinterrupt<activehigh>Pin8CLKDOMicrocontrollerclockoutputIII.SYSTEMSOFTWAREOESIGNA.Softwaredesignoffront-endmonitoringunitThemainfunctionofthefront-endmonitoringunitistocollecttemperatureandhumidityparameters,andsendtotheinformationcenter,soitsMCUsoftwareinadditiontothemainprogram,includingtemperaturedataacquisitionandhumiditydataacquisition,thecontrollingofthewirelesssendingletterlogic.Inordertoreducepowerconsumption,themicrocontrollerisalwaysworkinsleepmode[7],itwon'tgointothecollectionandsendingletterstatesuntilthewirelesschipiswokenupbytheinterrupt.Inthesystemaftertheinitializationiscompleted,theMCUdirectlygointothesleepmode,thensetflagB=0.Whenthewirelesschipreceivesawake-upsignal,whenexternalinterrupthappenstheinterruptrequestflagNIRQoutputlowtowakeuptheMCV.TheexternalinterruptwillsetflagB=1,andthenthesystemwillcollectdata.ThesystemflowchartisshowninFigure3.Figure3.MicrocontrollercontrollingprogramflowchartPartofthemainprogramofthefront-endmonitoringunitisshownbelow.voidmain<>{ZHU_Init<>;IA_Init<>;While<1>{if<B==1>{WEN<>;SHI<>;CRC<>;FA<>;B=0;}}}Inordertoensurethereliabilityofdatatransmission,designaddsan8-bitCRC<cyclicredundancycheck>character,theCRCgeneratorpolynomialis:ThegeneratorpolynomialofthelogiccircuitisshowninFigure4.AtthereceivingendusingthesameCRCcalculationinthedatareceiving,iftheremainderiszero,thenthechecksumresultiscorrect,orelseitisthewrongdata.InputMSBLSBFigure4.logiccircuitFront-endmonitoringunitssendfivebyteseachtimetothemonitoringcenterwhensendingdata,itsframeformatisshowninFigure5.AWDHWDLSHICRCFigure5.Thedataframeformatsendingfromfront-endmonitoringunitFigure6.TheflowchartmonitoringcentersystemAmongthem,thefirstbyteArepresentstheserialnumbersoffront-endmonitoringunits,suchasO1H,02Hand03H.ThesecondbyteWDHisonbehalfof8highbitsoftemperaturedata.ThethirdbyteWDLisonbehalfof8lowbitsoftemperaturedata.ThefourthbyteofSHIisconvertedhumiditydata.ThefifthbyteCRCisrepresentedtheremainderofthefirstfourbytesofCRCwhichisencoded.B.MicrocontrollersoftwaredesignofmonitoringcenterThemonitoringcenter'smainfunctionistosendpollingsignals,andtoreceivethecollectedtemperatureandhumiditydata.Ifthedataiscorrect,thedatawillbesenttothehostcomputerviaRS232.MonitoringcentersystemflowchartisshowninFigure6.Afterthepollingsignalisissued,themonitoringcenterwillwaitfor2secondstoreceivedata,ifthedataiserrorornotreceived,thenthesystemwillrecordthepollingdatasignalandfindthecauseoftheerrortofacilitateassoonaspossible.IV.CONCLUSIONThispaperpresentsanewlow-costdistributedtemperatureandhumidityacquisitionsystem.Thesystemcancollectdataofdifferentlocationsforcentralizedmonitoring.Theexperimentsshowthatthesystemdesignisreasonable,thetransmissionofthedataisaccurateandreliable,thetransmissiondistanceisabout100meters.Wirelesssystemisconvenientandflexible,itcanmeettheneedsofavarietyofcollectionsites,itisbroadprospectsfordevelopment.REFERENCES[1]MeiLifeng,SingleChipMicrocomputerPrincipleandInterfaceTechnology[M]Beijing:TsinghuaUniversityPress,2007.[2]ZhangKefan,ShuHua.IA4421digitalwirelesstemperaturesensordesign[J].Modemelectronictechnology,2008,20:189-191.[3]LiuXiaoyang,ZhouYantao,I-linebusstructureoftheDSI8B20serialnumbersearchalgorithm[J].ComputingTechnologyandAutomation,2010,29<1>:38-42.[4]ZhangPing,Increaseddual555Timerdigitalmethodofmeasuringhumidity[J].AutomationTechnologyandApplications,2007,<09>.[5]PanYuanyuan,YanGuozheng,HuangBiao,IA4420miniaturebidirectionalRFcommunicationsystem[1].ControlTechnology,2006,25<5>:81-83.[6]ZouQihong,LiuLan,ZhaoJun,LPC2131andIA4421-basedwirelessdataacquisitionsystem[J].InformationandElectronicEngineering,2009,<02>.[7]TingHuang,ShiGuoliang,WongKwan.Single-chipwirelesscommunicationsystemdesign[J].Microprocesso,2010,<03>.基于IA4421分布式溫度和濕度采集系統(tǒng)摘要—苗圃棚具有密植、數(shù)量大、參數(shù)變化緩慢、數(shù)據(jù)少的特點(diǎn),所以本文提出了一種基于短程無線電收發(fā)機(jī)IA4421芯片的分布式集中監(jiān)測系統(tǒng)。前端電路系統(tǒng)選擇STC89LE52RC單片機(jī)作為控制核心,完成濕度傳感器HS1101和溫度傳感器DS18B20電路的數(shù)據(jù)采集和無線電收發(fā)機(jī)IA4421芯片外圍電路的設(shè)計,CRC數(shù)據(jù)校驗(yàn),在完成數(shù)據(jù)中心前端系統(tǒng)和硬件設(shè)計之后,給出相應(yīng)的的軟件設(shè)計、相應(yīng)的流程圖和一些實(shí)例。關(guān)鍵字—IA4421；DS18B20；HS1101；CRC；無線傳輸；分布式1.簡介短程無線傳輸技術(shù)可以獲得多個苗圃棚的溫度和濕度并進(jìn)行集中監(jiān)測,這種類型的現(xiàn)場的溫度和濕度參數(shù)變化緩慢,因此采集數(shù)據(jù)的時間間隔可以更長一些,而且數(shù)據(jù)的數(shù)量對于每個樣本的價值很小；從技術(shù)的角度來看,利用許多監(jiān)控點(diǎn)的監(jiān)測系統(tǒng)更適合使用先進(jìn)的無線個域網(wǎng)絡(luò)。但是,從經(jīng)濟(jì)的角度來看,這樣的項(xiàng)目費(fèi)用太高。本文提出了基于無線IA4421芯片的分布式集中的監(jiān)測系統(tǒng),這個方案適用于上述類型的情況,而且有明顯的成本優(yōu)勢。2.系統(tǒng)和硬件設(shè)計系統(tǒng)組件在距離小<d<100m>和分散的區(qū)域內(nèi)有很多分布式的多個監(jiān)測點(diǎn),系統(tǒng)可以采用短程無線通信芯片組成的分布式無線監(jiān)控系統(tǒng),如圖1。有m個前端監(jiān)測和一個無線監(jiān)控系統(tǒng)中心,每個前端監(jiān)測有一個微控制器中心,收集溫度和濕度傳感器獲取的溫度和濕度參數(shù),微控制器通過前端無線通信芯片發(fā)送溫度和濕度參數(shù)到無線監(jiān)測中心。圖1分布式無線采集系統(tǒng)無線監(jiān)控中心是整個系統(tǒng)的中心,采取查詢檢測的方式把指令送給不同的前端監(jiān)測單元,前端監(jiān)測單元只接收自己的查詢命令,然后才發(fā)射出該單元采集的數(shù)據(jù)。該系統(tǒng)采取每3秒查詢一個前端檢測點(diǎn)的方式,每分鐘可以查詢20個監(jiān)測單元,可以更好的延長查詢周期或者減少查詢間隔來解決大規(guī)模的監(jiān)測站點(diǎn)的問題。B.前端監(jiān)測單元前端監(jiān)測單元負(fù)責(zé)采集現(xiàn)場的溫度和濕度參數(shù),并將采集到的數(shù)據(jù)送到無線監(jiān)測中心,電路原理圖如圖2所示。該設(shè)計采用STC89LE52RC作為控制器的核心,控制器利用串行口下載程序。這些指令和代碼充分兼容有六個中斷源、四個中斷優(yōu)先級、一個看門狗〔WDT>、時鐘頻率高達(dá)40MHz的51單片機(jī)[1]。該系統(tǒng)使用3.3V電壓穩(wěn)壓器ASM1117-3.3芯片給微控制器和無線通信芯片提供6V直流電壓。達(dá)拉斯公司的單總線數(shù)字溫度傳感器DS18B20應(yīng)用于溫度測量電路。這個設(shè)計使用了3管腳TO-92小尺寸封裝,溫度測量范圍-55°C到125°C,可編程為9-12位的A/D轉(zhuǎn)換和溫度分辨率高達(dá)至0.0625°C,用12位的轉(zhuǎn)換的溫度數(shù)字格式的轉(zhuǎn)換最大時間為750ms[2]。該設(shè)計使用了9位數(shù)字格式,默認(rèn)的轉(zhuǎn)換精度為0.5°C,轉(zhuǎn)換時間大約是100ms[3]。圖2前端監(jiān)測單元電路濕度采集在電路中使用濕度傳感器HS1101和定時器NE555,當(dāng)外界濕度變化和HS1101兩端的電容值變化時,HS1101可以影響定時器NE555電路的振蕩頻率,從而改變定時電路的輸出頻率。單片機(jī)系統(tǒng)通過測量其輸出的頻率計算濕度場。測量現(xiàn)場的濕度和輸出頻率對應(yīng)的關(guān)系[4]如表1所示。表1濕度和輸出頻率對應(yīng)的關(guān)系RF102030405060708090Fr722471006976685367286600646863306186C.無線收發(fā)機(jī)部分和無線監(jiān)測中心電路短程無線收發(fā)器IA4421芯片的設(shè)計應(yīng)用了集成聯(lián)接。這是一個高度集成、低功耗和需要很少外部組件、多通道、可編程、低成本、高性能的無線通信芯片[5]。芯片有一個高精度的可編程鎖相環(huán)頻率合成器,發(fā)送信道頻率偏移和接收機(jī)帶寬也可編程,在應(yīng)用中有很大的靈活性。該芯片采用移頻鍵控調(diào)制模式,可選擇的操作的頻帶有433M、868M和915M,當(dāng)接收機(jī)靈敏度是-109dBm和錯誤率是10-3、傳送速率是115.2kbpS、發(fā)送信道電流小于24mA、接收電流小于10mA時,最大的發(fā)送信道功率高達(dá)8dBm。待機(jī)電流只有0.3uA,最大的通信距離是100米至200米[6]。除了晶體振蕩器和天線的IA4421外圍電路只有兩個電感和兩個電容器,他們的具體參數(shù)取決于通信系統(tǒng)的頻率選擇。具體參數(shù)如表2所示。其他連接單片機(jī)管腳的名稱如表3所示,IA4421芯片的8管腳是輸出時鐘信號,沒有使用。當(dāng)IA4421芯片處在發(fā)射模式下,微控制器的NFFS管腳設(shè)置為高電平,那么微控制器給發(fā)射機(jī)發(fā)送初始化命令設(shè)置初始化設(shè)置,這是設(shè)置AAH的前序,設(shè)置2DD4的同步格式,波特率是9600bps,操作頻率是915MHz,然后發(fā)送命令8238H打開發(fā)射機(jī)。當(dāng)發(fā)射數(shù)據(jù)時nSEL管腳處于低電平,然后通過SDI寫數(shù)據(jù),每個時鐘周期寫一位。當(dāng)狀態(tài)標(biāo)志位SDO讀取的是1時,這意味著發(fā)射機(jī)已經(jīng)發(fā)送出一個字節(jié),微控制器將編寫下一個字節(jié)的數(shù)據(jù)。當(dāng)芯片在接收模式下,NFFS管腳設(shè)置為低電平,FIFO的輸出緩沖區(qū)直接連接到SDO管腳。發(fā)射模式要設(shè)置同步格式、波特率、操作頻率。IA4421有一個內(nèi)部的16RX數(shù)據(jù)FIFO管腳和接收機(jī)有接收中斷的FFIT管腳,當(dāng)接收到的數(shù)據(jù)位達(dá)到預(yù)置數(shù)時,管腳FFIT輸出高電平,命令微控制器從管腳SDO讀出數(shù)據(jù)。無線監(jiān)測核心部分的電路使用相同的微處理器和無線收發(fā)器芯片作為前端監(jiān)測單元,這個電路增加了RS232接口電路。表2IA4421的電路參數(shù)和頻率Freq〔MHzC6、C7〔pFL2〔nHL1<nH4334.72739086836.810091536.8100表3IA4421的管腳管腳名稱類型功能管腳1SDIDI串行控制數(shù)據(jù)輸入接口管腳2SCKDI串行控制時鐘輸入接口管腳3nSELDI串行控制芯片選擇輸入接口〔低電平有效管腳4SDODO支持總線串行數(shù)據(jù)輸出管腳5NIRQDO中斷請求輸出〔低電平有效管腳6NFFSDIFIFO選擇輸入〔低電平有效管腳7FFITDOFIFO中斷〔高電平有效管腳8CLKDO微控制器時鐘輸出系統(tǒng)的軟件設(shè)計前端監(jiān)測單元的軟件設(shè)計前端監(jiān)測單元的主要功能是采集溫度和濕度參數(shù),并把數(shù)據(jù)發(fā)送到信息中心,所以它的單片機(jī)軟件除了主程序之外,還包括溫度數(shù)據(jù)采集、濕度數(shù)據(jù)采集與無線傳輸信道邏輯的控制的程序。為了降低功耗,單片機(jī)常常工作在睡眠模式[7],它不會去采集和發(fā)送信道狀態(tài)直到有中斷喚醒無線通信芯片。在系統(tǒng)初始化完成后,單片機(jī)直接進(jìn)入睡眠模式,然后設(shè)置標(biāo)志位B=0。當(dāng)無線芯片接收到喚醒信號時,當(dāng)外部中斷發(fā)生在中斷請求標(biāo)志NIRQ輸出低電平時喚醒單片機(jī)。外部中斷將設(shè)置標(biāo)志位B=1,然后系統(tǒng)將采集數(shù)據(jù)。這個系統(tǒng)流程圖如圖3所示。接收到一個請求信號？定時器計接收到一個請求信號？定時器計時是否到？標(biāo)志B=0開始系統(tǒng)的初始化標(biāo)志B=1？溫度和濕度數(shù)據(jù)采集數(shù)據(jù)編碼和通過無線發(fā)射到監(jiān)測中心睡眠開始系統(tǒng)的初始化標(biāo)志B=1？溫度和濕度數(shù)據(jù)采集數(shù)據(jù)編碼和通過無線發(fā)射到監(jiān)測中心睡眠NY標(biāo)志B=0標(biāo)志B=0中斷開始中斷結(jié)束YNY 圖3微控制器控制程序流程圖前端監(jiān)測單元的部分主程序如下所示:voidmain<>{ZHU_Init<>;IA_Init<>;While<1>{if<B==1>