外文翻译-基于单片机的水温监控电路设计

毕业论文（设计）外文翻译毕设题目基于单片机的水温监控电路设计译文题目DS18B20单线温度传感器外文题目DS18B20SINGLEWIRETEMPERATURESENSOR专业班级09电子信息工程2班提交日期2013年5月15日外文资料DS18B20SINGLEWIRETEMPERATURESENSOR一FEATURESUNIQUE1WIREINTERFACEREQUIRESONLYONEPORTPINFORCOMMUNICATIONEACHDEVICEHASAUNIQUE64BITSERIALCODESTOREDINANONBOARDROMMULTIDROPCAPABILITYSIMPLIFIESDISTRIBUTEDTEMPERATURESENSINGAPPLICATIONSREQUIRESNOEXTERNALCOMPONENTSCANBEPOWEREDFROMDATALINEPOWERSUPPLYRANGEIS30VTO55VMEASURESTEMPERATURESFROM55CTO125C67FTO257F05CACCURACYFROM10CTO85CTHERMOMETERRESOLUTIONISUSERSELECTABLEFROM9TO12BITSCONVERTSTEMPERATURETO12BITDIGITALWORDIN750MSMAXUSERDEFINABLENONVOLATILENVALARMSETTINGSALARMSEARCHCOMMANDIDENTIFIESANDADDRESSESDEVICESWHOSETEMPERATUREISOUTSIDEOFPROGRAMMEDLIMITSTEMPERATUREALARMCONDITIONAVAILABLEIN8PINSO150MIL,8PINAND3PINTO92PACKAGESSOFTWARECOMPATIBLEWITHTHEDS1822APPLICATIONSINCLUDETHERMOSTATICCONTROLS,INDUSTRIALSYSTEMS,CONSUMERPRODUCTS,THERMOMETERS,ORANYTHERMALLYSENSITIVE二DESCRIPTIONTHEDS18B20DIGITALTHERMOMETERPROVIDES9TO12BITCENTIGRADETEMPERATUREMEASUREMENTSANDHASANALARMFUNCTIONWITHNONVOLATILEUSERPROGRAMMABLEUPPERANDLOWERTRIGGERPOINTSTHEDS18B20COMMUNICATESOVERA1WIREBUSTHATBYDEFINITIONREQUIRESONLYONEDATALINEANDGROUNDFORCOMMUNICATIONWITHACENTRALMICROPROCESSORITHASANOPERATINGTEMPERATURERANGEOF55CTO125CANDISACCURATETO05COVERTHERANGEOF10CTO85CINADDITION,THEDS18B20CANDERIVEPOWERDIRECTLYFROMTHEDATALINE“PARASITEPOWER”,ELIMINATINGTHENEEDFORANEXTERNALPOWERSUPPLYEACHDS18B20HASAUNIQUE64BITSERIALCODE,WHICHALLOWSMULTIPLEDS18B20STOFUNCTIONONTHESAME1WIREBUSTHUS,ITISSIMPLETOUSEONEMICROPROCESSORTOCONTROLMANYDS18B20SDISTRIBUTEDOVERALARGEAREAAPPLICATIONSTHATCANBENEFITFROMTHISFEATUREINCLUDEHVACENVIRONMENTALCONTROLS,TEMPERATUREMONITORINGSYSTEMSINSIDEBUILDINGS,EQUIPMENTORMACHINERY,ANDPROCESSMONITORINGANDCONTROLSYSTEMS三OVERVIEWFIGURE1SHOWSABLOCKDIAGRAMOFTHEDS18B20,ANDPINDESCRIPTIONSAREGIVENINTABLE1THE64BITROMSTORESTHEDEVICESUNIQUESERIALCODETHESCRATCHPADMEMORYCONTAINSTHE2BYTETEMPERATUREREGISTERTHATSTORESTHEDIGITALOUTPUTFROMTHETEMPERATURESENSORINADDITION,THESCRATCHPADPROVIDESACCESSTOTHE1BYTEUPPERANDLOWERALARMTRIGGERREGISTERSTHANDTL,ANDTHE1BYTECONFIGURATIONREGISTERTHECONFIGURATIONREGISTERALLOWSTHEUSERTOSETTHERESOLUTIONOFTHETEMPERATURETODIGITALCONVERSIONTO9,10,11,OR12BITSTHETH,TLANDCONFIGURATIONREGISTERSARENONVOLATILEEEPROM,SOTHEYWILLRETAINDATAWHENTHEDEVICEISPOWEREDDOWNTHEDS18B20USESDALLASEXCLUSIVE1WIREBUSPROTOCOLTHATIMPLEMENTSBUSCOMMUNICATIONUSINGONECONTROLSIGNALTHECONTROLLINEREQUIRESAWEAKPULLUPRESISTORSINCEALLDEVICESARELINKEDTOTHEBUSVIAA3STATEOROPENDRAINPORTTHEDQPININTHECASEOFTHEDS18B20INTHISBUSSYSTEM,THEMICROPROCESSORTHEMASTERDEVICEIDENTIFIESANDADDRESSESDEVICESONTHEBUSUSINGEACHDEVICESUNIQUE64BITCODEBECAUSEEACHDEVICEHASAUNIQUECODE,THENUMBEROFDEVICESTHATCANBEADDRESSEDONONEBUSISVIRTUALLYUNLIMITEDTHE1WIREBUSPROTOCOL,INCLUDINGDETAILEDEXPLANATIONSOFTHECOMMANDSAND“TIMESLOTS,”ISCOVEREDINTHE1WIREBUSSYSTEMSECTIONOFTHISDATASHEET。ANOTHERFEATUREOFTHEDS18B20ISTHEABILITYTOOPERATEWITHOUTANEXTERNALPOWERSUPPLYPOWERISINSTEADSUPPLIEDTHROUGHTHE1WIREPULLUPRESISTORVIATHEDQPINWHENTHEBUSISHIGHTHEHIGHBUSSIGNALALSOCHARGESANINTERNALCAPACITORCPP,WHICHTHENSUPPLIESPOWERTOTHEDEVICEWHENTHEBUSISLOWTHISMETHODOFDERIVINGPOWERFROMTHE1WIREBUSISREFERREDTOAS“PARASITEPOWER”ASANALTERNATIVE,THEDS18B20MAYALSOBEPOWEREDBYANEXTERNALSUPPLYONVDD。四OPERATIONMEASURINGTEMPERATURETHECOREFUNCTIONALITYOFTHEDS18B20ISITSDIRECTTODIGITALTEMPERATURESENSORTHERESOLUTIONOFTHETEMPERATURESENSORISUSERCONFIGURABLETO9,10,11,OR12BITS,CORRESPONDINGTOINCREMENTSOF05C,025C,0125C,AND00625C,RESPECTIVELYTHEDEFAULTRESOLUTIONATPOWERUPIS12BITTHEDS18B20POWERSUPINALOWPOWERIDLESTATETOINITIATEATEMPERATUREMEASUREMENTANDATODCONVERSION,THEMASTERMUSTISSUEACONVERTT44HCOMMANDFOLLOWINGTHECONVERSION,THERESULTINGTHERMALDATAISSTOREDINTHE2BYTETEMPERATUREREGISTERINTHESCRATCHPADMEMORYANDTHEDS18B20RETURNSTOITSIDLESTATEIFTHEDS18B20ISPOWEREDBYANEXTERNALSUPPLY,THEMASTERCANISSUE“READTIMESLOTS”SEETHE1WIREBUSSYSTEMSECTIONAFTERTHECONVERTTCOMMANDANDTHEDS18B20WILLRESPONDBYTRANSMITTING0WHILETHETEMPERATURECONVERSIONISINPROGRESSAND1WHENTHECONVERSIONISDONEIFTHEDS18B20ISPOWEREDWITHPARASITEPOWER,THISNOTIFICATIONTECHNIQUECANNOTBEUSEDSINCETHEBUSMUSTBEPULLEDHIGHBYASTRONGPULLUPDURINGTHEENTIRETEMPERATURECONVERSIONTHEBUSREQUIREMENTSFORPARASITEPOWERAREEXPLAINEDINDETAILINTHEPOWERINGTHEDS18B20SECTIONOFTHISDATASHEET。THEDS18B20OUTPUTTEMPERATUREDATAISCALIBRATEDINDEGREESCENTIGRADEFORFAHRENHEITAPPLICATIONS,ALOOKUPTABLEORCONVERSIONROUTINEMUSTBEUSEDTHETEMPERATUREDATAISSTOREDASA16BITSIGNEXTENDEDTWOSCOMPLEMENTNUMBERINTHETEMPERATUREREGISTERSEEFIGURE2THESIGNBITSSINDICATEIFTHETEMPERATUREISPOSITIVEORNEGATIVEFORPOSITIVENUMBERSS0ANDFORNEGATIVENUMBERSS1IFTHEDS18B20ISCONFIGUREDFOR12BITRESOLUTION,ALLBITSINTHETEMPERATUREREGISTERWILLCONTAINVALIDDATAFOR11BITRESOLUTION,BIT0ISUNDEFINEDFOR10BITRESOLUTION,BITS1AND0AREUNDEFINED,ANDFOR9BITRESOLUTIONBITS2,1AND0AREUNDEFINEDTABLE2GIVESEXAMPLESOFDIGITALOUTPUTDATAANDTHECORRESPONDINGTEMPERATUREREADINGFOR12BITRESOLUTIONCONVERSIONS。五OPERATIONALARMSIGNALINGAFTERTHEDS18B20PERFORMSATEMPERATURECONVERSION,THETEMPERATUREVALUEISCOMPAREDTOTHEUSERDEFINEDTWOSCOMPLEMENTALARMTRIGGERVALUESSTOREDINTHE1BYTETHANDTLREGISTERSSEEFIGURE3THESIGNBITSINDICATESIFTHEVALUEISPOSITIVEORNEGATIVEFORPOSITIVENUMBERSS0ANDFORNEGATIVENUMBERSS1THETHANDTLREGISTERSARENONVOLATILEEEPROMSOTHEYWILLRETAINDATAWHENTHEDEVICEISPOWEREDDOWNTHANDTLCANBEACCESSEDTHROUGHBYTES2AND3OFTHESCRATCHPADASEXPLAINEDINTHEMEMORYSECTIONOFTHISDATASHEET。六THANDTLREGISTERFORMATFIGURE3ONLYBITS11THROUGH4OFTHETEMPERATUREREGISTERAREUSEDINTHETHANDTLCOMPARISONSINCETHANDTLARE8BITREGISTERSIFTHEMEASUREDTEMPERATUREISLOWERTHANOREQUALTOTLORHIGHERTHANTH,ANALARMCONDITIONEXISTSANDANALARMFLAGISSETINSIDETHEDS18B20THISFLAGISUPDATEDAFTEREVERYTEMPERATUREMEASUREMENTTHEREFORE,IFTHEALARMCONDITIONGOESAWAY,THEFLAGWILLBETURNEDOFFAFTERTHENEXTTEMPERATURECONVERSIONTHEMASTERDEVICECANCHECKTHEALARMFLAGSTATUSOFALLDS18B20SONTHEBUSBYISSUINGANALARMSEARCHECHCOMMANDANYDS18B20SWITHASETALARMFLAGWILLRESPONDTOTHECOMMAND,SOTHEMASTERCANDETERMINEEXACTLYWHICHDS18B20SHAVEEXPERIENCEDANALARMCONDITIONIFANALARMCONDITIONEXISTSANDTHETHORTLSETTINGSHAVECHANGED,ANOTHERTEMPERATURECONVERSIONSHOULDBEDONETOVALIDATETHEALARMCONDITION。七POWERINGTHEDS18B20THEDS18B20CANBEPOWEREDBYANEXTERNALSUPPLYONTHEVDDPIN,ORITCANOPERATEIN“PARASITEPOWER”MODE,WHICHALLOWSTHEDS18B20TOFUNCTIONWITHOUTALOCALEXTERNALSUPPLYPARASITEPOWERISVERYUSEFULFORAPPLICATIONSTHATREQUIREREMOTETEMPERATURESENSINGORTHATAREVERYSPACECONSTRAINEDFIGURE1SHOWSTHEDS18B20SPARASITEPOWERCONTROLCIRCUITRY,WHICH“STEALS”POWERFROMTHE1WIREBUSVIATHEDQPINWHENTHEBUSISHIGHTHESTOLENCHARGEPOWERSTHEDS18B20WHILETHEBUSISHIGH,ANDSOMEOFTHECHARGEISSTOREDONTHEPARASITEPOWERCAPACITORCPPTOPROVIDEPOWERWHENTHEBUSISLOWWHENTHEDS18B20ISUSEDINPARASITEPOWERMODE,THEVDDPINMUSTBECONNECTEDTOGROUNDINPARASITEPOWERMODE,THE1WIREBUSANDCPPCANPROVIDESUFFICIENTCURRENTTOTHEDS18B20FORMOSTOPERATIONSASLONGASTHESPECIFIEDTIMINGANDVOLTAGEREQUIREMENTSAREMETREFERTOTHEDCELECTRICALCHARACTERISTICSANDTHEACELECTRICALCHARACTERISTICSSECTIONSOFTHISDATASHEETHOWEVER,WHENTHEDS18B20ISPERFORMINGTEMPERATURECONVERSIONSORCOPYINGDATAFROMTHESCRATCHPADMEMORYTOEEPROM,THEOPERATINGCURRENTCANBEASHIGHAS15MATHISCURRENTCANCAUSEANUNACCEPTABLEVOLTAGEDROPACROSSTHEWEAK1WIREPULLUPRESISTORANDISMORECURRENTTHANCANBESUPPLIEDBYCPPTOASSURETHATTHEDS18B20HASSUFFICIENTSUPPLYCURRENT,ITISNECESSARYTOPROVIDEASTRONGPULLUPONTHE1WIREBUSWHENEVERTEMPERATURECONVERSIONSARETAKINGPLACEORDATAISBEINGCOPIEDFROMTHESCRATCHPADTOEEPROMTHISCANBEACCOMPLISHEDBYUSINGAMOSFETTOPULLTHEBUSDIRECTLYTOTHERAILASSHOWNINFIGURE4THE1WIREBUSMUSTBESWITCHEDTOTHESTRONGPULLUPWITHIN10SMAXAFTERACONVERTT44HORCOPYSCRATCHPAD48HCOMMANDISISSUED,ANDTHEBUSMUSTBEHELDHIGHBYTHEPULLUPFORTHEDURATIONOFTHECONVERSIONTCONVORDATATRANSFERTWR10MSNOOTHERACTIVITYCANTAKEPLACEONTHE1WIREBUSWHILETHEPULLUPISENABLEDTHEDS18B20CANALSOBEPOWEREDBYTHECONVENTIONALMETHODOFCONNECTINGANEXTERNALPOWERSUPPLYTOTHEVDDPIN,ASSHOWNINFIGURE5THEADVANTAGEOFTHISMETHODISTHATTHEMOSFETPULLUPISNOTREQUIRED,ANDTHE1WIREBUSISFREETOCARRYOTHERTRAFFICDURINGTHETEMPERATURECONVERSIONTIMETHEUSEOFPARASITEPOWERISNOTRECOMMENDEDFORTEMPERATURESABOVE100CSINCETHEDS18B20MAYNOTBEABLETOSUSTAINCOMMUNICATIONSDUETOTHEHIGHERLEAKAGECURRENTSTHATCANEXISTATTHESETEMPERATURESFORAPPLICATIONSINWHICHSUCHTEMPERATURESARELIKELY,ITISSTRONGLYRECOMMENDEDTHATTHEDS18B20BEPOWEREDBYANEXTERNALPOWERSUPPLYINSOMESITUATIONSTHEBUSMASTERMAYNOTKNOWWHETHERTHEDS18B20SONTHEBUSAREPARASITEPOWEREDORPOWEREDBYEXTERNALSUPPLIESTHEMASTERNEEDSTHISINFORMATIONTODETERMINEIFTHESTRONGBUSPULLUPSHOULDBEUSEDDURINGTEMPERATURECONVERSIONSTOGETTHISINFORMATION,THEMASTERCANISSUEASKIPROMCCHCOMMANDFOLLOWEDBYAREADPOWERSUPPLYB4HCOMMANDFOLLOWEDBYA“READTIMESLOT”DURINGTHEREADTIMESLOT,PARASITEPOWEREDDS18B20SWILLPULLTHEBUSLOW,ANDEXTERNALLYPOWEREDDS18B20SWILLLETTHEBUSREMAINHIGHIFTHEBUSISPULLEDLOW,THEMASTERKNOWSTHATITMUSTSUPPLYTHESTRONGPULLUPONTHE1WIREBUSDURINGTEMPERATURECONVERSIONS八64BITLASEREDROMCODEEACHDS18B20CONTAINSAUNIQUE64BITCODESEEFIGURE6STOREDINROMTHELEASTSIGNIFICANT8BITSOFTHEROMCODECONTAINTHEDS18B20S1WIREFAMILYCODE28HTHENEXT48BITSCONTAINAUNIQUESERIALNUMBERTHEMOSTSIGNIFICANT8BITSCONTAINACYCLICREDUNDANCYCHECKCRCBYTETHATISCALCULATEDFROMTHEFIRST56BITSOFTHEROMCODEADETAILEDEXPLANATIONOFTHECRCBITSISPROVIDEDINTHECRCGENERATIONSECTIONTHE64BITROMCODEANDASSOCIATEDROMFUNCTIONCONTROLLOGICALLOWTHEDS18B20TOOPERATEASA1WIREDEVICEUSINGTHEPROTOCOLDETAILEDINTHE1WIREBUSSYSTEMSECTIONOFTHISDATASHEET九MEMORYTHEDS18B20SMEMORYISORGANIZEDASSHOWNINFIGURE7THEMEMORYCONSISTSOFANSRAMSCRATCHPADWITHNONVOLATILEEEPROMSTORAGEFORTHEHIGHANDLOWALARMTRIGGERREGISTERSTHANDTLANDCONFIGURATIONREGISTERNOTETHATIFTHEDS18B20ALARMFUNCTIONISNOTUSED,THETHANDTLREGISTERSCANSERVEASGENERALPURPOSEMEMORYALLMEMORYCOMMANDSAREDESCRIBEDINDETAILINTHEDS18B20FUNCTIONCOMMANDSSECTIONBYTE0ANDBYTE1OFTHESCRATCHPADCONTAINTHELSBANDTHEMSBOFTHETEMPERATUREREGISTER,RESPECTIVELYTHESEBYTESAREREADONLYBYTES2AND3PROVIDEACCESSTOTHANDTLREGISTERSBYTE4CONTAINSTHECONFIGURATIONREGISTERDATA,WHICHISEXPLAINEDINDETAILINTHECONFIGURATIONREGISTERSECTIONOFTHISDATASHEETBYTES5,6,AND7ARERESERVEDFORINTERNALUSEBYTHEDEVICEANDCANNOTBEOVERWR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警信号DS18B20温度转换完成后，温度值与用户定义的2个报警触发值存储在1个字节的TH和TL寄存器。符号位（S）表示温度值的正负S0时为正值，S1为负值。TH和TL寄存器是非易失（EEPROM），因此他们将保留设备掉电时的数据。TH和TL可通过暂存器中字节2和3获得，此内容在本数据表内存部分解释。六TH和TL寄存器格式只有温度寄存器4中的11位用于和TL的比较中，由于TH和TL都是8位寄存器。如果测量温度低于或等于TL或超过TH，报警情况存在而且报警标志将设置在DS18B20的内部。每个温度测量后，这个标志位将被更新，因此，如果报警条件消失，下一个温度转换后，该标志位将被关闭。主设备可以通过搜索ECH命令检查总线上所有DS18B20S报警标志位的状态。任何有设置报警标志位的DS18B20S将响应命令，所以主设备可以决定到底是哪个DS18B20S在经历一个报警条件。如果报警的情况存在，TH和TL设置已经改变了，另一个温度转换应该去验证报警条件。七DS18B20的驱动该传感器DS18B20可以用外部电源接VDD端供电，或者它可以工作在“寄生电源”模式下，这种模式允许DS18B20在没有外部电源下工作。寄生电源在远程或者空间受限情况下感温是非常有用的。寄生功率控制电路，其中当总线引脚为高电平时，力部门宿舍从DS18B201通过连接单总线的DQ端“偷”电。当总线是高电平或者总线是低电平，而一些能量存贮在CPP中来提供电源，“偷”来的电位DS18B20提供驱动。当DS18B20在寄生电源模式下使用时，VDD引脚必须接地。在寄生电源模式下，单总线和CPP可以提供足够的电流给DS18B20的大部分操作，只要指定的时间和电压的要求得到满足（参考本数据手册DC电气特性和AC电气特性章节）。然而，当DS18B20温度转换或复制暂存器的数据到EEPROM时，工作电流可高达15毫安。这个电流会导致无法接受的电压下降，整个单总线电阻压降减小，更多的电流可以由寄生电源供应。为了确保DS18B20有足够的电流供应，无论正在发生温度转换或复制暂存器的数据到EEPROM，单总线都必须接一个强上拉电阻。这可以通过使用一个MOSFET以直接把总线电压下降到如图4所示。单总线必须在转换T44H或暂存器复制48H命令发出后，10秒内（最大）转换到强上拉状态，而且总线必须在转换（TCONV）或数据传输（TWR10MS）期间通过上拉保持高电平。在单总线上拉使能时，其他活动不能发生。该DS18B20的也可以采用的连接外部电源到VDD脚上的传统方法。这种方法的优点是不需要MOSFET的上拉，而且单总线可以在进行温度转换时间自由地进行其他操作。在100以上的高温时不推荐使用寄生电源，因为在这些温度下存在较高泄漏电流，DS18B20可能无法维持通信。对于像在这种高温下的使用，强烈建议由一个DS18B20的外部电源供电。在某些情况下，总线主机可能不知道DS18B20S是外部电源还是寄生电源供电。主机需要这些信息来确定是否强大的总线上拉应在温