RIID硬件原理及其实现.ppt

RFID硬件原理简介以AS3990阅读器芯片为例,涉及的一些基础概念RFID硬件结构及各部分作用AS3990阅读器芯片介绍,基带：指信号的频谱从零频率附近开始。频带：指信号的频谱具有带通形式且中心频率远离零频。携带有消息；适合在信道中传输。,ASK调制和PSK调制,PSK,ASK信号波形(OOK),RFID使用的ASK信号的调制度是80100%。,ASK解调,非相干解调（包络检波法）,相干解调,PLL(锁相环),混频（器件的非线性）,(光的颜色),RFID中发射机混频结构,低中频超外差零中频中频选为0（本振与载波同频）时的超外差结构。,GEN2协议,EPCphysicallayerInterrogator!tag:Carrier:860-960Mhz(dependingonlocalregulations)EU:865.5-867.6Mhz,US:902-928Mhz,dividedintochannels(200kHz,500kHz)yes,FDMAispossible!Modulation:ASK(DSB-ASK,SSB-ASK,PR-ASKtagundestandsall)Encoding:PIEBandwidth:26.7-128kbit/sTag!interrogator:Modulation:ASKorPSK(readerunderstandsall)Encoding:readerdecidesFM0baseband(40-640kbit/s)Millerofasubcarrier(5-320kbit/s)DataratedependsonDivideRatioandTRcal,selectedbyreaderQUERYcommand,RFID系统工作原理,1.读写器开始工作之后，先内向空间发送860960MHz频率范围的载波，激活标签。2.标签从射频信号获得能量后，响应读写器发送的指令。3.读写器开始发送带调制的命令信息，标签从载有信息的调制信号获取能量的同时得到指令，标签依照指令做出响应。,相互认证通过之后，阅读器会向电子标签发出读、写、锁定、kill、盘存等操作指令。,阅读器发射未调载波信号作用,为标签供电；为标签反向散射信号提供载；为零中频接收机提供本振。,电磁反向散射,阅读器发出的射频信号传播标签的天线上，标签需要向将阅读器发送信息时，就通过调整天线的复阻抗，改变天线对电磁波的反射系数，从而对反射波进行相位或振幅的调制。,一种反射调制的电路实现,RFID系统工作波形,RFID读写器硬件组成,AS3990/AS3991芯片简介,各部分硬件结构各部分功能、工作原理只涉及少芯片引脚各部分相关寄存器设置单独由word文档列出,Compriseof,analoganddigitalfunctionalitywithcompleteEPCGen2orISO18000-6Cdigitalprotocolsupport.on-boardPLLsectionwithintegratedVCOsupplysectionDACandADCsectionHostinterfacesectionConfigurationregisters(configuresoperationofallblocks),Powerupandoperations,Needstobecorrectlysuppliedvia.VEXTandVEXT2pinsandenabledvia.ENpinAtpower-up.Theconfigurationregistersarepresettoadefaultoperationmode.Accessandchangeregisters(P23)tochooseotheroptions.Communication,Communication,Thecommunicationbetweenthereaderandthetransponderfollowsthereadertalkfirstmethod.Afterpower-upandconfiguringIC,thehostsystemstartscommunicationbyturningontheRFfieldbysettingoptionbitrf_on。,Transmittingandreceivingmodes,NormalDataMode:theTXandRXdataistransferredthroughtheFIFOregisterandallprotocoldataprocessingisdoneinternally.DirectDataMode:thedataprocessingisdonebythehostsystem.,接口总线(interfacebus),parallel10-pinbuscanbeconfiguredandusedasaserialperipheralinterface(SPI)exclusive,cannotswitchbetweentheminasingleapplication.TheparallelmodeisselectedifallIOpinsarelowduringlowtohightransitionoftheENpin(enable).,Thereaderwillalwaysbehaveasthe“slave”connectedtothehostsystem(MCU),whichbehavesasthe“master”device.Thehostsysteminitiatesallcommunications.ThereaderhasanIRQpintoaskforhostsystemattention.,CommunicationisinitializedbyaStartcondition,whichshouldbefollowedbyanAddressorCommandword.TheAddressandCommandwordsare8-bitslong.Communicationisclosedbyanappropriatestopcondition.,命令/地址格式,Continuousaddressmodenoncontinuousaddressmodecommandmode.ContinuousaddressmodeneedstobeclosedbyStopContconditionwhiletheothertwomodesneedtobeterminatedbyStopSglcondition.,communicationmodes,Continuousaddressmode,Contmode=1,thefirstdatathatfollowstheaddressiswritten(orread)to(from)thegivenaddress.Foreachadditionaldata,theaddressisincrementedbyone.canbeusedtowritepartofthecontrolregistersinasinglestreamwithoutchangingtheaddress.,组合模式,Registers12,14,15,16,and17arethreebytesdeep.TheycanbeaccessedbyContinuousaddressmodeonly.Theleastsignificantbyteisaccessedfirst.Itispossibletoaccessonlydeepregisterinasinglecommunicationstream。,The24bytesdeepFIFOregistercanbeaccessedbyContinuousaddressmodeonly.)Itisallowedtousecommunicationstreamcombinedofcommandmodeandaddressmode.Example:ResetFIFO,Transmit,writeto1D,1Efortransmissionlength,andcontinuouslyto1FforfillingFIFOwithtransmissiondata.,Start=startconditionAdr=addresswithContbitlowAdrc=addresswiththeContbithighCmd=commandbyteData=databyteStopSgl=stopconditionforterminationofthecommandornon-continuousaddressmodeStopCont=stopconditionforterminationofthecontinuousaddressmode,命令后可以是地址，可以是命令，但不可以是数据。地址后只能是数据。地址和命令是定义的，数据是随机的。这样可以保证不会混淆,并行接口（以StopSgl结尾）,VDD_I0,此引脚很重要，定义了芯片与MCU的通信电平(1.8-5.5v)。如果使用芯片内部高压器供电(VDD_D)，则应将VDD_IO与VDD_D相连。如果MCU单独供电，则应调节相关设置寄存器。,SUPPLY,Asetof3.4Vregulatorsisusedforsupplyingthereferenceblock,ADandDAconverters,lowfrequencyreceivercells,theRFpart,anddigitalpart.ItispossibletousethedigitalpartsupplyVDD_DforsupplyingtheexternalMCUwithacurrentconsumptionupto20mA.,Anadditional4.8VregulatorisusedfortheinputRFmixerssupply.TheinputofthisregulatorisVEXT,outputisVDD_MIXpin.TheVEXTvoltageneedstobebetween5.3Vand5.5V.,PowerDownMode:ENpinlow(EN=L).theOAD2pinnotbeconnected.NormalMode:EN=H.Thechipisreadytomovetotransmitorreceiveoperation.StandbyMode:stby=H.Inthestandbymodetheregulators,referencevoltagesystem,andcrystaloscillatorareoperatinginlowpowermode;butthePLL,transmitteroutputstagesandreceiverareswitchedoff.,PLL,composedofavoltagecontroloscillator(VCO),prescaler,mainandreferencedivider,phasefrequencydetector,chargepump,andloopfilter.Allbuildingblocksexcludingtheloopfilterarecompletelyintegrated.,externalRFsourcecanbeused.ItisalsopossibletouseexternalVCOandinternalPLLcircuitry.(使用于对相位噪声要求较高的场合),每次启动RF模块之前，主机都要先对PLL模块各项参数进行设置（主要是预定标）。跳频(Frequencyhopping)：主机以命令形式控制。（相关命令参考手册）。,protocolprocessingdigitalpartshapingModulatoramplifiercircuitry.,发射机(TRANSMITTER),三种工作模式,NormalMode(正常模式)DirectModeUsingParralleleInterfaceDirectModeusingSerialinterface(SPI),NormalMode,Innormalmode,allsignalprocessing(protocolcoding,addingpreambleorframe-syncandCRC,signalshaping,andmodulation)isdoneinternally.Frame-sync:帧同步。,Thetransmissionisstartedbysendingthetransmitcommandfollowedbyinformationonthenumberofbytesthatshouldbetransmittedandthedata.ThenumberofbytesneedstobewrittenintheTXlengthregistersandthedatatotheFIFOregister.ThetransmissionactuallystartswhenthefirstdatabyteiswrittenintotheFIFO.,ThesecondpossibilityistostarttransmissionwithoneofthedirectGen2commands(Query,QueryRep,QueryAdjust,ACK,NAK,ReqRN).Inthiscase,thetransmissionisstartedafterreceivingthecommand.,Thereaderchipstartstransmissionandsendsaninterruptrequestwhenonly3bytesareleftintheFIFO.Wheninterruptisreceived,thehostsystemneedstoreadtheIRQstatusregister