giao tiep I2C.pdf

http://codientu.org Tc gi: Nguyn Ch Linh Tmtt:GiithiuchungvI2C cimchungvI2C:giaothc,ach Ccchhotng:masterslave,multimasterModuleI2CtrongViiukhinPIC Cutrcphncng Chhotng:Master,Slave,Multimaster

1. GiithiuchungvI2C

Ngynaytrongcchthnginthini,rtnhiuICshaythitbngoivicnphigiaotipviccICshaythitbkhcgiaotipvithgiibnngoi.Vimctiutchiuquchophncngttnhtvimchinngin,Phillipsphttrinmtchungiaotipnitip2dycgilI2C.I2CltnvitttcacmtInterIntergratedCircuitBusgiaotipgiaccICvinhau.

LchsI2CThmvoy(Phnnysthmsau)

I2CmcdcphttrinbiPhilips,nhngncrtnhiunhsnxutICtrnthgiisdng.I2Ctrthnhmtchuncngnghipchoccgiaotipiukhin,cthkraymtvitntuingoiPhilipsnh:TexasIntrument(TI),MaximDallas,analogDevice,NationalSemiconductorBusI2CcsdnglmbusgiaotipngoivichortnhiuloiICkhcnhaunhccloiViiukhin8051,PIC,AVR,ARM,chpnhnhRAMtnh(StaticRam),EEPROM,bchuynitngts(ADC),stngt(DAC),ICiukhinLCD,LED

Hnh1.1.BUSI2Cvccthitbngoivi

http://codientu.org Tc gi: Nguyn Ch Linh

1.1. cimgiaotipI2C

MtgiaotipI2Cgmc2dy:SerialData(SDA)vSerialClock(SCL).SDAlngtruyndliu2hng,cnSCLlngtruynxungnghvchtheomthng.Nhhnhvtrn,khimtthitbngoiviktnivongI2CthchnSDAcansnividySDAcabus,chnSCLsnividySCL.

Hnh1.2.KtnithitbvobusI2Cchchun(Standardmode)

vchnhanh(Fastmode)

MidySDAhaySCLucniviinpdngcanguncpthngquamtintrkoln(pullupresistor).ScnthitcaccintrkonylvchngiaotipI2Ccaccthitbngoivithngldngccmngh(opendrainoropencollector).Gitrcaccintrnykhcnhautyvotngthitbvchungiaotip,thngdaongtrongkhong1Kn4.7K.

Trlivihnh1.1,tathycrtnhiuthitb(ICs)cngcktnivomtbusI2C,tuynhinskhngxyrachuynnhmlngiaccthitb,bimithitbscnhnrabimtachduynhtvimtquanhch/ttntitrongsutthigianktni.Mithitbcthhotngnhlthitbnhndliuhaycthvatruynvanhn.Hotngtruynhaynhncntythucvovicthitblch(master)hayt(slave).

MtthitbhaymtICkhiktnivibusI2C,ngoimtach(duynht)phnbit,ncnccuhnhlthitbch(master)hayt(slave).Tisaolicsphnbitny?lvtrnmtbusI2Cthquyniukhinthucvthitbch(master).Thitbchnmvaitrtoxungnghchotonhthng,khigiahaithitbch/tgiaotipththitbchcnhimvtoxungnghvqunlachcathitbttrongsutqutrnhgiaotip.Thitbchgivaitrchng,cnthitbtgivaitrbngtrongvicgiaotip.


Hnh1.3.Truynnhndliugiach/t

Nhnhnhtrntathyxungnghchcmthngtchnt,cnlungdliucthitheohaihng,tchnthayngclitnch.

VdliutruyntrnbusI2C,mtbusI2Cchuntruyn8bitdliuchngtrnngtruynvitcl100Kbits/sChchun(Standardmode).Tctruyncthlnti400Kbits/sChnhanh(Fastmode)vcaonhtl3,4Mbits/sChcaotc(Highspeedmode).

MtbusI2Ccthhotngnhiuchkhcnhau:

- Mtchmtt(onemasteroneslave)

- Mtchnhiut(onemastermultislave)

- Nhiuchnhiut(Multimastermultislave)

Dchno,mtgiaotipI2Cudavoquanhch/t.GithitmtthitbAmungidliunthitbB,qutrnhcthchinnhsau:

ThitbA(Ch)xcnhngachcathitbB(t),cngvivicxcnhach,thitbAsquytnhvicchayghivothitbt

ThitbAgidliutithitbB

ThitbAktthcqutrnhtruyndliu

KhiAmunnhndliutB,qutrnhdinranhtrn,chkhclAsnhndliutB.Tronggiaotipny,AlchcnBvnlt.Chititvicthitlpmtgiaotipgiahaithitbscmtchitittrongccmcdiy.

1.2. STARTandSTOPconditions

STARTvSTOPlnhngiukinbtbucphickhimtthitbchmunthitlpgiaotipvimtthitbnotrongmngI2C.STARTliukinkhiu,bohiubtucagiaotip,cnSTOPbohiuktthcmtgiaotip.HnhdiymtiukinSTARTvSTOP.

Banukhichathchinqutrnhgiaotip,chaingSDAvSCLumccao(SDA=SCL=HIGH).LcnybusI2Cccoildi(busfree),snsngchomtgiaotip.HaiiukinSTARTvSTOPlkhngththiutrongvicgiaotipgiaccthitbI2Cvinhau


Hnh1.4.iukinSTARTvSTOPcabusI2C

iukinSTART:mtschuynitrngthitcaoxungthptrnngSDAtrongkhingSCLangmccao(cao=1;thp=0)bohiumtiukinSTART

iukinSTOP:MtschuynitrngthitmcthplncaotrnngSDAtrongkhingSCLangmccao.

ChaiiukinSTARTvSTOPuctorabithitbch.SautnhiuSTART,busI2Ccoinhangtrongtrangthilmvic(busy).BusI2Csri,snsngchomtgiaotipmisautnhiuSTOPtphathitbch.

SaukhicmtiukinSTART,trongquatrnhgiaotip,khicmttnhiuSTARTclplithayvmttnhiuSTOPthbusI2Cvntiptctrongtrngthibn.TnhiuSTARTvlpliSTARTucchcnnggingnhaulkhitomtgiaotip.

1.3. nhdngdliutruyn

DliuctruyntrnbusI2Ctheotngbit,bitdliuctruynitimisndngcaxungnghtrndySCL,qutrnhthayibitdliuxyrakhiSCLangmcthp.

Hnh1.5.Qutrnhtruyn1bitdliu

Mibytedliuctruyncdil8bits.Slngbytecthtruyntrongmtlnlkhnghnch.MibytectruynitheosaulmtbitACKbohiunhndliu.Bitctrngscaonht(MSB)sctruyniutin,ccbtsctruynilnlt.Sau8xungclocktrndySCL,8bitdliuctruyni.Lcnythitbnhn,saukhinhn8btdliuskoSDAxungmcthptomtxungACKngvixungclockth9trndySDAbohiunhn8bit.ThitbtruynkhinhncbitACKstiptcthchinqutrnhtruynhocktthc.

http://lab3i.com Tc gi: Nguyn Ch Linh

Hnh1.6.DliutruyntrnbusI2C

Hnh1.7.BitACKtrnbusI2C

Truyn Nhn

SDA=data_bit Buffer=databitKimtraxemtruyn8bitcha

Clock=8? NO

YES ACK? NO

BufferFull? NO

YES

SendACK

YES

Next_byteorSTOP

STOP

ReadBuffer

Hnh1.8.Luthuttonqutrnhtruyngnhndliu

hhttp://lab3i.co Tc gi: Nguyn Ch Linh

MtbytetruynickmtheobitACKliukinbtbuc,nhmmbochoqutrnhtruynnhncdinrachnhxc.Khikhngnhncngachhaykhimunktthcqutrnhgiaotip,thitbnhnsgimtxungNotACK(SDAmccao)bochothitbchbit,thitbchstoxungSTOPktthchaylplimtxungSTARTbtuqutrnhmi.

1.4. nhdngachthitb

Mithitbngoivithamgiavobusi2cucmtachduynht,nhmphnbitgiaccthitbvinhau.diachl7bit,iucnghaltrnmtbusI2Ctacthphnbittia128thitb.KhithitbchmungiaotipvingoivinotrnbusI2C,nsgi7bitachcathitbrabusngaysauxungSTART.Byteutincgisbaogm7bitachvmtbtth8iukhinhngtruyn.

Hnh1.8.Cutrcbytedliuutin

Mimtthitbngoiviscmtachringdonhsnxutranquynh.achcthlcnhhaythayi.Ringbitiukhinhngsquynhchiutruyndliu.Nubitnybng0cnghalbytedliutiptheosausctruyntchnt,cnngclinubng1thccbytetheosaubyteutinsldliutcontginconch.Victhitlpgitrchobitnydoconchthihnh,contstytheogitrmcsphnhitngngnconch.

1.5. TruyndliutrnbusI2C,chMasterSlave

Victruyndliudinragiaconchvcont.Dliutruyncththeo2hng,tchnthayngcli.Hngtruyncquynhbibitth8 trongbyteutinctruyni.

Hnh1.9.Qutrnhtruyndliu


Truyndliutchnt(ghidliu):Thitbchkhimunghidliuncont,qutrnhthchinl:

ThitbchtoxungSTART

Thitbchgiachcathitbtmncngiaotipcngvibit

=0rabusvixungACKphnhitcont

KhinhncxungACKbonhndinngthitbt,conchbtugidliunconttheotngbytemt.TheosaumibytenyulmtxungACK.Slngbytetruynlkhnghnch.

Ktthcqutrnhtruyn,conchsaukhitruynbytecuistoxungSTOPbohiuktthc.

Hnh1.10.Ghidliutchnt

Truyndliuttnch(cdliu):Thitbchmuncdliutthitbt,qutrnhthchinnhsau:

Khibusri,thitbchtoxungSTART,bohiubtugiaotip

Thitbchgiachcathitbtcngiaotipcngvibit =1vixungACKtphathitbt

SauxungACKdutin,thitbtsgitngbyterabus,thitbchsnhndliuvtrvxungACK.Slngbytekhnghnch

Khimunktthcqutrnhgiaotip,thitbchgixungNotACKvtoxungSTOPktthc.

Hnh1.11.cdliutthitbt

Qutrnhkthpghivcdliu:giahaixungSTARTvSTOP,thitbchcththchinvicchayghinhiuln,vimthaynhiuthitb.thchinvic,saumtqutrnhghihayc,thitbchlplimtxungSTARTvligiliachcathitbtvbtumtqutrnhmi.


Hnh1.12.Qutrnhphihpc/ghidliu

ChgiaotipMasterSlavelchcbntrongmtbusI2C,tonbbuscqunlbimtmasterduynht.Trongchnyskhngxyratnhtrngxungtbushaymtngbxungclockvchcmtmasterduynhtcthtoxungclock.

1.6. ChMultiMaster

TrnbusI2Ccthcnhiuhnmtmasteriukhinbus.KhibusI2CshotngchMultiMaster.

Vnnyscbnthosau.

2. ModuleI2CtrongViiukhinPIC

Vinhngtinchemli,khigiaotipI2CctchhpcngtrongkhnhiuloiViiukhinkhcnhau.TrongccloiViiukhinPICdngMidrangephbintiVitNam,cht16F88michtrphncngI2C,cnccloi16F84,16F628thkhngc.VinhngloiViiukhinkhngchtrphncnggiaotipI2C,sdngtacthdngphnmmlptrnh,khitasvitmtchngtrinhdiukhin2chnbtkcaViiukhinnthchingiaotipI2C(cchmSTART,STOP,WRITE,READ).TrongbivitnytacpnvicsdnggiaotipI2CcaccloiPICctchhpkhiI2Csntrongn,mcthlViiukhinPIC16F877A.

2.1. cimphncng

HnhdiychracutrcphncngcakhiiukhinGiaotipnitipngb(MSSP)hotngchI2C.KhiI2Ccdychcnng,hotngc2chlMASTER(ch)vSLAVE(t),cngtxyrakhiciukinSTARThaySTOPxyra,nhmnhrngI2Ccdihaykhnng(chcnngMultimaster).Chachcthl7bithay10bit.

KhiI2Cc6thanhghiiukhinhotng,l:

SSPCON:Thanhghiiukhin

SSPCON2:Thanhghiiukhinth2

SSPSTAT:Thanhghitrngthi


SSPBUF:Thanhghibmtruynnhn

SSPSR:Thanhghidch

SSPADD:Thanhghiach

CcthanhghiSSPCON,SSPBUF,SSPADDvSSPSON2cthtruycpc/ghic.ThanhghiSSPSRkhngthtruycptrctip,lthanhghidichdliurahayvo.CcthanhghiSSPCON,SSPCON2vSSPSTATcnhachbit,mibitcchcnngring.nghacatngthanhghivcamibittrongtngthanhghiccpktrongtiliuDatasheetcaPICvtrongtiliuTUT04.02.PVN.MAFDcabnMnh,tikhngcpthmy.TrongtiliunaygtistptrungvovicsdngkhiI2CcaPICccchMastervSlavetrongphnmmbindchCchoPIClCCS

Hnh2.1.CutrckhiI2CtrongPIC

2.2. CchthcsdngModuleI2CtrongCCS

TrongviclptrnhchoPICsdnggiaotipI2Ccantrongccngdng,ngilptrnhcththchinmtcchddngvitrnhdchCCS.Niddngylchvmtcphplnh,takhngcnsdngnhiuculnhkhnhnhtronglptrnhASM.


Vickhito,chnchhotngvthchingiaotipcaI2CccchmdngsncaCCSthchin.CchmlitkdiylcaphinbnCCS3.242,l:

i2c_isr_state():ThngbotrngthigiaotipI2C

i2c_start():ToiukinSTART

i2c_stop():ToiukinSTOP

i2c_read():cgitrtthitbI2C,trvgitr8bit

i2c_write():Ghigitr8bitnthitbI2C

sdngkhiI2Ctasdngkhaibosau:

#usei2c(ch_,tc,sda=PIN_C4,scl=PIN_C3)

Ch:MasterhaySlave

Tc:Slow(100KHz)hayFast(400KHz)

SDAvSCLlccchni2ctngngcaPIC

Saukhaibotrn,tacthsdngcchmnutrnthchin,xlccgiaotipi2cviccthitbngoivikhc.

Cntipna

3. Ktlun

Documents

giao tiep I2C.pdf