DS18B20中英文资料外文翻译文献Word文件下载.docx

DS18B20中英文资料外文翻译文献Word文件下载.docx

《DS18B20中英文资料外文翻译文献Word文件下载.docx》由会员分享，可在线阅读，更多相关《DS18B20中英文资料外文翻译文献Word文件下载.docx（26页珍藏版）》请在冰点文库上搜索。

lEachDevicehasaUnique64-BitSerialCodeStoredinanOn-BoardROM

lMulti-dropCapabilitySimplifiesDistributedTemperature-SensingApplications

lRequiresNoExternalComponents

15

lCanBePoweredfromDataLine;

PowerSupplyRangeis3.0Vto5.5V

lMeasuresTemperaturesfrom-55°

C（-67°

Fto+257°

F）

l±

CAccuracyfrom-10°

C

lThermometerResolutionisUserSelectablefrom9to12Bits

lConvertsTemperatureto12-BitDigitalWordin750ms（Max）

lUser-DefinableNonvolatile（NV）AlarmSettings

lAlarmSearchCommandIdentifiesandAddressesDevicesWhoseTemperatureisOutsideProgrammedLimits

lSoftwareCompatiblewiththeDS1822

lApplicationsIncludeThermostaticControls,IndustrialSystems,ConsumerProducts,Thermometers,orAnyThermallySensitiveSystem

3.OVERVIEW

Figure1showsablockdiagramoftheDS18B20,andpindescriptionsaregiveninthePinDescriptiontable.The64-bitROMstoresthedevice’suniqueserialcode.Thescratchpadmemorycontainsthe2-bytetemperatureregisterthatstoresthedigitaloutputfromthetemperaturesensor.Inaddition,thescratchpadprovidesaccesstothe1-byteupperandloweralarmtriggerregisters（THandTL）andthe1-byteconfigurationregister.Theconfigurationregisterallowstheusertosettheresolutionofthetemperatureto-digitalconversionto9,10,11,or12bits.TheTH,TL,andconfigurationregistersarenonvolatile（EEPROM）,sotheywillretaindatawhenthedeviceispowereddown.

TheDS18B20usesMaxim’sexclusive1-Wirebusprotocolthatimplementsbuscommunicationusingonecontrolsignal.Thecontrollinerequiresaweakpullupresistorsincealldevicesarelinkedtothebusviaa3-stateoropen-drainport（theDQpininthecaseoftheDS18B20）.Inthisbussystem,themicroprocessor（themasterdevice）identifiesandaddressesdevicesonthebususingeachdevice’sunique64-bitcode.Becauseeachdevicehasauniquecode,thenumberofdevicesthatcanbeaddressedononeDS18B20busisvirtuallyunlimited.The1-Wirebusprotocol,

includingdetailedexplanationsofthecommandsand“timeslots,‖iscoveredinthe1-WireBusSystemsection.

Vpu

4.7K

PARASITEPOWERCIRCUIT

MEMORYCONTROLLOGIC

DQ

TEMPERATURESENSOR

INTERNALVdd

64-BITROMAND

1-WIREPORT

ALARMHIGHTRIGGER（TH）

GND

Cpp

SCRATCHPAD

ALARMLOWTRIGGER（TL）

CONFIGURATIONREGISTER

Vdd

POWER-SUPPLYSENSE

8-BITCRCGENERATOR

AnotherfeatureoftheDS18B20istheabilitytooperatewithoutanexternalpowersupply.Powerisinsteadsuppliedthroughthe1-WirepullupresistorviatheDQpinwhenthebusishigh.Thehighbussignalalsochargesaninternalcapacitor（CPP）,whichthensuppliespowertothedevicewhenthebusislow.Thismethodofderivingpowerfromthe 1-Wirebusisreferredtoas―parasitepower.‖Asanalternative,theDS18B20mayalsobepoweredbyanexternalsupplyonVDD.

Figure1.DS18B20BlockDiagram

4.OPERATION—MEASURINGTEMPERATUR

ThecorefunctionalityoftheDS18B20isitsdirect-to-digitaltemperaturesensor.Theresolutionofthetemperaturesensorisuser-configurableto9,10,11,or12bits,correspondingtoincrementsof0.5°

C,0.25°

C,0.125°

C,and0.0625°

C,respectively.Thedefaultresolutionatpower-upis12-bit.TheDS18B20powersupinalow-poweridlestate.ToinitiateatemperaturemeasurementandA-to-Dconversion,themastermustissueaConvertT[44h]command.Followingtheconversion,theresultingthermaldataisstoredinthe2-bytetemperatureregisterinthescratchpadmemoryandtheDS18B20returnstoitsidlestate.IftheDS18B20ispoweredbyanexternalsupply,themastercanissue―readtimeslots‖（seethe1-WireBusSystemsection）aftertheConvertTcommandandtheDS18B20willrespondbytransmitting0while

thetemperatureconversionisinprogressand1whentheconversionisdone.IftheDS18B20ispoweredwithparasitepower,thisnotificationtechniquecannotbeusedsincethebusmustbepulledhighbyastrongpullupduringtheentiretemperatureconversion.

bit7

bit6

bit5

bit4

bit3

23

22

21

20

2-1

TheDS18B20outputtemperaturedataiscalibratedindegrees Celsius;

forFahrenheitapplications,alookuptableorconversionroutinemustbeused.Thetemperaturedataisstoredasa16-bitsign-extendedtwo’scomplementnumberinthetemperatureregister（seeFigure2）.Thesignbits（S）indicateifthetemperatureispositiveornegative:

forpositivenumbersS=0andfornegativenumbersS=1.IftheDS18B20isconfiguredfor12-bitresolution,allbitsinthetemperatureregisterwillcontainvaliddata.For11-bitresolution,bit0isundefined.For10-bitresolution,bits1and0areundefined,andfor9-bitresolutionbits2,1,and0areundefined.Table1givesexamplesofdigitaloutputdataandthecorrespondingtemperaturereadingfor12-bitresolutionconversions.

LSByte

bit15

bit14

bit13

bit12

bit11

MSByte

S

bit2 bit1 bit0

2-2 2-3 2-4

bit10 bit9 bit8

26 25 24

Figure2.TemperatureRegisterFormat

TEMPERATURE

DIGITALOUTPUT

（BINARY）

（HEX）

+125℃

0000011111010000

07D0H

+25.0625℃

0000000110010001

0191H

0℃

0000000000000000

0000H

-25.0625℃

1111111001101111

FE6FH

-55℃

1111110010010000

FC90H

Table1.Temperature/DataRelationship

5.64-BITLASEREDROMCODE

EachDS18B20containsaunique64–bitcode（seeFigure3）storedinROM.Theleastsignificant8bitsoftheROMcodecontaintheDS18B20’s1 -Wirefamilycode:

28h.Thenext48bitscontainauniqueserialnumber.Themostsignificant8bitscontaina cyclicredundancycheck（CRC）bytethatiscalculatedfromthefirst56bitsoftheROMcode.The64-bitROMcodeandassociatedROMfunctioncontrollogicallowtheDS18B20tooperateasa1-Wiredeviceusingtheprotocoldetailedinthe1-WireBusSystemsection.

8-BITCRC 48-BITSERIALNUMBER

8-BITFAMILYCODE

MSBLSBMSBLSBMSB

Figure3.64-BitLaseredROMCode

6.MEMORY

TheDS18B20’smemoryisorganized asshowninFigure4.ThememoryconsistsofanSRAMscratchpadwithnonvolatileEEPROMstorageforthehighandlowalarmtriggerregisters（THandTL）andconfigurationregister.NotethatiftheDS18B20alarmfunctionisnotused,theTHandTLregisterscanserveasgeneral-purposememory.

Byte0andbyte1ofthescratchpadcontaintheLSBandtheMSBofthetemperatureregister,respectively.Thesebytesareread-only.Bytes2and3provideaccesstoTHandTLregisters.Byte4containstheconfigurationregisterdata.Bytes5,6,and7arereservedforinternalusebythedeviceandcannotbeoverwritten.Byte8ofthescratchpadisread-onlyandcontainstheCRCcodeforbytes0through7ofthescratchpad.TheDS18B20generatesthisCRCusingthemethoddescribedintheCRCGenerationsection.

Dataiswrittentobytes2,3,and4ofthescratchpadusingtheWriteScratchpad[4Eh]command;

thedatamustbetransmittedtotheDS18B20startingwiththeleastsignificantbitofbyte2.Toverifydataintegrity,thescratchpadcanberead（usingtheReadScratchpad[BEh]command）afterthedataiswritten.Whenreadingthescratchpad,dataistransferredoverthe 1-Wirebusstartingwiththeleastsignificant

bitofbyte0.TotransfertheTH,TLandconfigurationdatafromthescratchpadtoEEPROM,themastermustissuetheCopyScratchpad[48h]command.

Byte0 TemperatureLSB

Byte1 TemperatureMSB

Byte2 THRegisterforhightemperature

Byte3 TLRegisterforlowtemperature

Byte4 ConfigurationRegister

Byte5 Reserved（FFH）

Byte6 Reserved（OCH）

Byte7 Reserved（IOH）

Byte8 CyclicRedundancyChecks（CRC）

Figure4.DS18B20MemoryMap

7.CONFIGURATIONREGISTER

Byte4ofthescratchpadmemorycontainstheconfigurationregister,whichisorganizedasillustratedinFigure5.TheusercansettheconversionresolutionoftheDS18B20usingtheR0andR1bitsinthisregisterasshowninTable2.Thepower-updefaultofthesebitsisR0=1andR1=1（12-bitresolution）.Notethatthereisadirecttradeoffbetweenresolutionandconversiontime.Bit7andbits0to4intheconfigurationregisterarereservedforinternalusebythedeviceandcannotbeoverwritten.

BIT7

BIT6

BIT5

BIT4 BIT3

BIT2 BIT1 BIT0

TM

R1

R0

1 1

1 1 1

Figure5.ConfigurationRegister

R0

R1

RESOLUTION（BIT MAXCONVERSION

S） TIME

0

9

93.75ms

1

10

187.5ms

11

375ms

12

750ms

Table2.ThermometerResolutionConfiguration

8.1-WIREBUSSYSTEM

The1-Wirebussystemusesasinglebusmastertocontrolone