数字式温湿度检测系统设计英文文献

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1、IntroductiontodigitaltemperaturesensorDS1820FEATURES•Unique1–WireTMinterfacerequiresonlyoneportpinforcommunication•Multidropcapabilitysimplifiesdistributedtemperaturesensingapplications•Requiresnoexternalcomponents•Canbepoweredfromdataline•Zerostandbypowerrequired•Measures

2、temperaturesfrom–55°Cto+125°Cin0.5°Cincrements.Fahrenheitequivalentis–67°Fto+257°Fin0.9°Fincrements•Temperatureisreadasa9–bitdigitalvalue.•Convertstemperaturetodigitalwordin200ms(typ.)•User–definable,nonvolatiletemperaturealarmsettings•Alarmsearchcommandidentifiesandaddres

3、sesdeviceswhosetemperatureisoutsideofprogrammedlimits(temperaturealarmcondition)•Applicationsincludethermostaticcontrols,industrialsystems,consumerproducts,thermometers,oranythermallysensitivesystemDESCRIPTIONTheDS1820DigitalThermometerprovides9–bittemperaturereadingswhich

4、indicatethetemperatureofthedevice.Informationissentto/fromtheDS1820overa1–Wireinterface,sothatonlyonewire(andground)needstobeconnectedfromacentralmicroprocessortoaDS1820.Powerforreading,writing,andperformingtemperatureconversionscanbederivedfromthedatalineitselfwithnoneedf

5、oranexternalpowersource.BecauseeachDS1820containsauniquesiliconserialnumber,multipleDS1820scanexistonthesame1–Wirebus.Thisallowsforplacingtemperaturesensorsinmanydifferentplaces.ApplicationswherethisfeatureisusefulincludeHVACenvironmentalcontrols,sensingtemperaturesinsideb

6、uildings,equipmentormachinery,andinprocessmonitoringandcontrol.DETAILEDPINDESCRIPTIONOVERVIEWTheblockdiagramofFigure1showsthemajorcomponentsoftheDS1820.TheDS1820hasthreemaindatacomponents:1)64–bitlaseredROM,2)temperatureandsensor,3)nonvolatiletemperaturealarmtriggersTHandT

7、L.Thedevicederivesitspowerfromthe1–Wirecommunicationlinebystoringenergyonaninternalcapacitorduringperiodsoftimewhenthesignallineishighandcontinuestooperateoffthispowersourceduringthelowtimesofthe1–Wirelineuntilitreturnshightoreplenishtheparasite(capacitor)supply.Asanaltern

8、ative,theDS1820mayalsobepoweredfromanexternal5voltssupply.CommunicationtotheDS1820isviaa1