/大學(xué)生部落-大學(xué)生第一門戶社區(qū)/大學(xué)生部落-大學(xué)生第一門戶社區(qū)1Singlechip433/868/915MHzTransceivernRF905FEATURESTruesinglechipGFSKtransceiverinasmall32-pinpackage(32LQFN5x5mm)ShockBurstmodeforlowpoweroperationPowersupplyrange1.9to3.6VMultichanneloperationETSI/FCCCompatibleChannelswitchingtime650sExtremelylowcostBillofMaterial(BOM)NoexternalSAWfilterAdjustableoutputpowerupto10dBmCarrierdetectforlistenbeforetransmitprotocolsDataReadysignalwhenavaliddatapackageisreceivedortransmittedAddressMatchfordetectionofincomingpackageAutomaticretransmissionofdatapackagesAutomaticCRCandpreamblegenerationAPPLICATIONSWirelessdatacommunicationAlarmandsecuritysystemsHomeAutomationRemotecontrolSurveillanceAutomotiveTelemetryIndustrialsensorsKeylessentryToysGENERALDESCRIPTIONnRF905isasingle-chipradiotransceiverforthe433/868/915MHzISMband.Thetransceiverconsistsofafullyintegratedfrequencysynthesiser,receiverchainwithdemodulator,apoweramplifier,acrystaloscillatorandamodulator.TheShockBurstTMfeatureautomaticallyhandlespreambleandCRC.ConfigurationiseasilyprogrammablebyuseoftheSPIinterface.Currentconsumptionisverylow,intransmitonly11mAatanoutputpowerof-10dBm,andinreceivemode12.5mA.Builtinpowerdownmodesmakespowersavingeasilyrealizable.MODESOFOPERATIONThenRF905hastwoactive(RX/TX)modesandtwopower-savingmodesACTIVEMODESShockBurstRXShockBurstTXPOWERSavingModesPowerdownandSPI-programmingStandbyandSPI-programmingThenRF905modeisdecidedbythesettingsofTRX_CE,TX_ENandPWR_UP./大學(xué)生部落-大學(xué)生第一門戶社區(qū)/大學(xué)生部落-大學(xué)生第一門戶社區(qū)2nRFShockBurstModesThenRF905usestheNordicVLSIShockBurstfeature.ShockBurstTMmakesitpossibletousethehighdatarateofferedbythenRF905withouttheneedofacostly,high-speedmicrocontroller(MCU)fordataprocessing/clockrecovery.ByplacingallhighspeedsignalprocessingrelatedtoRFprotocolon-chip,thenRF905offerstheapplicationmicrocontrollerasimpleSPIinterface,thedatarateisdecidedbytheinterface-speedthemicrocontrolleritselfsetsup.Byallowingthedigitalpartoftheapplicationtorunatlowspeed,whilemaximizingthedatarateontheRFlink,thenRF905ShockBurstmodereducestheaveragecurrentconsumptioninapplications.InShockBurstTMRX,AddressMatch(AM)andDataReady(DR)notifiestheMCUwhenavalidaddressandpayloadisreceivedrespectively.InShockBurstTMTX,thenRF905automaticallygeneratespreambleandCRC.DataReady(DR)notifiestheMCUthatthetransmissioniscompleted.Alltogether,thismeansreducedmemorydemandintheMCUresultinginalowcostMCU,aswellasreducedsoftwaredevelopmenttime.TypicalShockBurstTX1.WhentheapplicationMCUhasdataforaremotenode,theaddressofthereceivingnode(TX-address)andpayloaddata(TX-payload)areclockedintonRF905viatheSPIinterface.TheapplicationprotocolorMCUsetsthespeedoftheinterface.2.MCUsetsTRX_CEandTX_ENhigh,thisactivatesanRF905ShockBursttransmission.3.nRF905ShockBurst:Radioisautomaticallypoweredup.Datapackageiscompleted(preambleadded,CRCcalculated).Datapackageistransmitted(100kbps,GFSK,Manchester-encoded).DataReadyissethighwhentransmissioniscompleted.4.IfAUTO_RETRANissethigh,thenRF905continuouslyretransmitsthepackageuntilTRX_CEissetlow.5.WhenTRX_CEissetlow,thenRF905finishestransmittingtheoutgoingpackageandthensetsitselfintostandbymode.TheShockBurstTMmodeensuresthatatransmittedpackagethathasstartedalwaysfinishesregardlessofwhatTRX_ENandTX_ENissettoduringtransmission.Thenewmodeisactivatedwhenthetransmissioniscompleted.PleaseseesubsequentchaptersfordetailedtimingFortestpurposessuchasantennatuningandmeasuringoutputpoweritispossibletosetthetransmittersothataconstantcarrierisproduced.TodothisTRX_CEmustbemaintainedhighinsteadofbeingpulsed.InadditionAutoRetransmitshouldbeswitchedoff.Aftertheburstofdatahasbeensentthenthedevicewillcontinuetosendtheunmodulatedcarrier.TypicalShockBurstRX1.ShockBurstTMRXisselectedbysettingTRX_CEhighandTX_ENlow.2.After650snRF905ismonitoringtheairforincomingcommunication.3.WhenthenRF905sensesacarrieratthereceivingfrequency,CarrierDetect(CD)pinissethigh.4.Whenavalidaddressisreceived,AddressMatch(AM)pinissethigh./大學(xué)生部落-大學(xué)生第一門戶社區(qū)/大學(xué)生部落-大學(xué)生第一門戶社區(qū)35.Whenavalidpackagehasbeenreceived(correctCRCfound),nRF905removesthepreamble,addressandCRCbits,andtheDataReady(DR)pinissethigh.6.MCUsetstheTRX_CElowtoenterstandbymode(lowcurrentmode).7.MCUcanclockoutthepayloaddataatasuitablerateviatheSPIinterface.8.Whenallpayloaddataisretrieved,nRF905setsDataReady(DR)andAddressMatch(AM)lowagain.9.ThechipisnowreadyforenteringShockBurstTMRX,ShockBurstTMTXorpowerdownmode.IfTRX_CEorTX_ENischangedduringanincomingpackage,thenRF905changesmodeimmediatelyandthepackageislost.However,iftheMCUissensingtheAddressMatch(AM)pin,itknowswhenthechipisreceivinganincomingpackageandcanthereforedecidewheathertowaitfortheDataReady(DR)signalorenteradifferentmode.PowerDownModesInpowerdownthenRF905isdisabledwithminimalcurrentconsumption,typicallyminimizeaveragecurrentconsumptionandmaximizingbatterylifetime.Theconfigurationwordcontentismaintainedduringpowerdown.StandbymodeStandbymodeisusedtominimizeaveragecurrentconsumptionwhilemaintainingshortstartuptimestoShockBurstTMRXandShockBurstTMTX.Inthismodepartofthecrystaloscillatorisactive.Currentconsumptionisdependentoncrystalfrequency,Ex.IftheuP-clock(pin3)ofnRF905isenabled,currentconsumptionincreasesandisdependentontheloadcapacitanceandfrequency.Theconfigurationwordcontentismaintainedduringstandby.DevieconfigurationAllconfigurationofthenRF905isviatheSPIinterface.Theinterfaceconsistsoffiveregisters；aSPIinstructionsetisusedtodecidewhichoperationshallbeperformed.TheSPIinterfacecanonlybeactivatedwhenthechipisinstandbyorpowerdownmode.SPIRegistersconfigurationTheSPIinterfaceconsistsoffiveinternalregisters.Aregisterread-backmodeisimplementedtoallowverificationoftheregistercontents.Figure6SPIinterfaceandthefiveinternalregisters./大學(xué)生部落-大學(xué)生第一門戶社區(qū)/大學(xué)生部落-大學(xué)生第一門戶社區(qū)4StatusRegisterRegistercontainsstatusofDataReady(DR)andAddressMatch(AM).RFConfigurationRegisterRegistercontainstransceiversetupinformationsuchasfrequencyandoutputpowerext.TXAddersRegistercontainsaddressoftargetdevice.Howmanybytesusedissetintheconfigurationregister.TXPayloadRegistercontainingthepayloadinformationtobesentinaShockBurstTMpackage.Howmanybytesusedissetintheconfigurationregister.RXPayloadRegisterc