数电课件ch-09-stPPT格式课件下载.ppt

数电课件ch-09-stPPT格式课件下载.ppt

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,DigitalFundamentalsTenthEditionFloyd,Chapter9,2008PearsonEducation,Ashiftregisterisanarrangementofflip-flopswithimportantapplicationsinstorageandmovementofdata.Somebasicdatamovementsareillustratedhere.,Summary,BasicShiftRegisterOperations,Datain,Datain,Datain,Datain,Datain,Dataout,Dataout,Dataout,Dataout,Dataout,Serialin/shiftright/serialout,Serialin/shiftleft/serialout,Parallelin/serialout,Parallelin/parallelout,Serialin/parallelout,Rotateright,Rotateleft,Summary,Serial-in/SerialoutShiftRegister,ShiftregistersareavailableinICformorcanbeconstructedfromdiscreteflip-flopsasisshownherewithafive-bitserial-inserial-outregister.,Eachclockpulsewillmoveaninputbittothenextflip-flop.Forexample,a1isshownasitmovesacross.,1,1,1,1,1,1,CLK,CLK,CLK,CLK,CLK,Summary,ABasicApplication,Anapplicationofshiftregistersisconversionofserialdatatoparallelform.,Forexample,assumethebinarynumber1011isloadedsequentially,onebitateachclockpulse.,CLK,CLK,CLK,CLK,Summary,The74HC164AShiftRegister,The74HC164AisaCMOS8-bitserialin/paralleloutshiftregister.VCCcanbefrom+2.0Vto+6.0V.,OneofthetwoserialdatainputsmaybeusedasanactiveHIGHenabletogatetheotherinput.Ifnoenableisneeded,theotherserialinputcanbeconnectedtoVCC.The74HC164AhasanactiveLOWasynchronousclear.Dataisenteredontheleading-edgeoftheclock.,CLK,Q0,Q1,Q2,Q3,CLR,Q4,Q5,Q6,Q7,Serialinputs,A,B,Summary,Waveformsforthe74HC164A,Samplewaveformsforthe74HC164Aareshown.NoticethatBactsasanactiveHIGHenableforthedataonAasdiscussed.,CLK,Q0,Q1,Q2,Q3,CLR,Q4,Q5,Q6,Q7,Serialinputs,A,B,Outputs,Clear,Clear,AswithCMOSdevices,unusedinputsshouldalwaysbeconnectedtoalogiclevel;@#@unusedoutputsshouldbeleftopen.,Summary,Parallelin/SerialoutShiftRegister,Shiftregisterscanbeusedtoconvertparalleldatatoserialform.Alogicdiagramforthistypeofregisterisshown:

@#@,D0,D1,D2,D3,Q0,Q1,Q2,Q3,SHIFT/LOAD,CLK,Serialdataout,Summary,The74HC165ShiftRegister,The74HC165isaCMOS8-bitparallelin/serialoutshiftregister.Thelogicsymbolisshown:

@#@,D0,D1,D2,D3,D4,D5,D6,D7,Q7,Q7,SH/LD,CLK,SER,CLKINH,Summary,The74HC165ShiftRegister,AMultisimsimulationofthe74165Aisshown.Thewordgeneratorisusedasasourceforthepatternshowninthegreenprobes.,PatternisloadedwhenJ1isLOW,Q7islabeledQHinMultisim,Summary,The74HC165ShiftRegister,Herethescopeisopenedandyoucanobservethepattern.TheMSBisHIGHandisontheQ7outputassoonasLOADisLOW.,Load,Q7,Clk,Summary,BidirectionalShiftRegister,BidirectionalshiftregisterscanshiftthedataineitherdirectionusingaRIGHT/LEFTinput.,ThelogicanalyzersimulationshowsabidirectionalshiftregistersuchastheoneshowninFigure9-19ofthetext.NoticetheHIGHlevelfromtheSerialdatainisshiftedatfirstfromQ3towardQ0.,CLK,RIGHT/LEFT,Serialdatain,Q0,Q1,Q2,Q3,Shiftright,Shiftleft,Summary,BidirectionalShiftRegister,CLK,RIGHT/LEFT,Serialdatain,Q0,Q1,Q2,Q3,Shiftright,Shiftleft,Question,Answer,Seedisplay,Shiftright,Shiftleft,Summary,UniversalShiftRegister,Auniversalshiftregisterhasbothserialandparallelinputandoutputcapability.The74HC194isanexampleofa4-bitbidirectionaluniversalshiftregister.,D0,D1,D2,D3,CLK,SLSER,Q0,Q1,Q2,Q3,SRSER,S1,S0,CLR,Samplewaveformsareonthefollowingslide,Summary,UniversalShiftRegister,Summary,ShiftRegisterCounters,Shiftregisterscanformusefulcountersbyrecirculatingapatternof0sand1s.TwoimportantshiftregistercountersaretheJohnsoncounterandtheringcounter.,TheJohnsoncountercanbemadewithaseriesofDflip-flops,Summary,JohnsonCounter,RedrawingthesameJohnsoncounter（withouttheclockshown）illustrateswhyitissometimescalledasa“twisted-ring”counter.,Summary,JohnsonCounter,TheJohnsoncounterisusefulwhenyouneedasequencethatchangesbyonlyonebitatatimebutithasalimitednumberofstates（2n,wheren=numberofstages）.,Thefirstfivecountsfora4-bitJohnsoncounterthatisinitiallyclearedare:

@#@CLKQ0Q1Q2Q3,00001000110011101111011100110001,01234567,Whataretheremaining3states?

@#@,Question,Summary,RingCounter,TheringcountercanalsobeimplementedwitheitherDflip-flopsorJ-Kflip-flops.,Hereisa4-bitringcounterconstructedfromaseriesofDflip-flops.Noticethefeedback.,LiketheJohnsoncounter,itcanalsobeimplementedwithJ-Kflipflops.,Summary,RingCounter,RedrawingtheRingcounter（withouttheclockshown）showswhyitisa“ring”.,Thedisadvantagetothiscounteristhatitmustbepreloadedwiththedesiredpattern（usuallyasingle0or1）andithasevenfewerstatesthanaJohnsoncounter（n,wheren=numberofflip-flops.,Ontheotherhand,ithastheadvantageofbeingself-decodingwithauniqueoutputforeachstate.,Summary,Rin