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3.1.2SDCardIdentificationProcedure
ProceduresforCommonOperations
Figure12.MMCCardIdentificationProcedure
TheSDcardidentificationprocedureis:
1.UsetheMMCcommandregister(MMCCMD)toissuetheGO_IDLE_STATE(CMD0)commandtothe
MMCcards.UsingMMCMDtoissuetheCMD0commandputsallcards(MMCandSD)intheidle
stateandnoresponsefromthecardsisexpected.
2.UseMMCCMDtoissuetheAPP_CMD(CMD55)command(R1responseisexpected)toindicatethat
thecommandthatfollowsisanapplicationcommand.
3.UseMMCCMDtosendtheSD_SEND_OP_COND(ACMD41)commandwiththevoltagerange
supported(R3responseisexpected)toSDcards.UsingMMCCMDtosendtheACMD41command
allowsthehosttoidentifyandrejectcardsthatdonotmatchtheVDDrangethatthehostsupports.
4.UseMMCCMDtosendtheALL_SEND_CID(CMD2)command(R2responseisexpected)totheMMC
cards.UsingMMCCMDtosendtheCMD2commandnotifiesallcardstosendtheiruniquecard
identification(CID)number.ThereshouldonlybeonecardthatsuccessfullysendsitsfullCIDnumber
tothehost.Thesuccessfulcardgoesintoidentificationstateanddoesnotrespondtothiscommand
again.
5.UseMMCMDtoissuetheSEND_RELATIVE_ADDR(CMD3)command(R1responseisexpected)in
ordertoaskthecardtopublishanewrelativeaddressforfutureusetoaddressthecardindata
transfermode.
Note:ThiscommandisonlyaddressedtothecardthatsuccessfullysentitsCIDnumberin
step4.Thiscardnowgoesintostandbymode.Thiscardalsochangesitsoutputdrivers
fromopen-draintopush-pull.ItstopsreplyingtotheCMD2command,allowingforthe
identificationofothercards.
30MultimediaCard(MMC)/SecureDigital(SD)CardControllerSPRUE30B–September2006
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