Filter
Top Products
www.ti.com
ARG HIGH
RCA ADDRESS HIGH
STATUS 0
NEXT DATA BYTE
DATA TX
MMC controller
register content
MMC controller
register
RCA ADDRESS LOW
ARG LOW
SEL/DESEL. CARD
COMMAND
Select one card with relative
card address (RCA) while
de−selecting the other cards.
SET_BLOCKLEN
BLK ADDRESS LOW
BLK ADDRESS HIGH
COMMAND
ARG LOW
ARG HIGH
READ_MULT_BLOCK
COMMAND
Load starting block address
into the high and low argument
registers. Load block
length register with the block
length value. Start the operation by
Is CRCRD = 1?
Is DRRDY = 1?
loading a READ_MULTIPLE_BLOCK
command into the command
register.
Check TOUTRD bit to verify
that the read operation has not
timed−out. Check CRCRD bit for
any read CRC errors. Check DRRDY
to see if a new byte is in the data
STOP_TRANSMISSION
COMMAND
Terminate the multiple−block
read operation.
Is TOUTRD = 1?
receive register.
3.9MMC/SDModeMultiple-BlockReadOperationUsingEDMA
ProceduresforCommonOperations
Figure17.MMC/SDModeMultiple-BlockReadOperation
Toperformamultiple-blockread,thesameblocklengthmustbesetinboththeMMC/SDcontrollerand
thecard.
Theprocedureforthisoperationisasfollows:
1.Writethecard’srelativeaddresstotheMMCargumentregisters(MMCARGHandMMCARGL).Load
thehighpartoftheaddresstoMMCARGHandthelowpartoftheaddresstoMMCARGL.
2.ReadcardCSDtodeterminethecard'smaximumblocklength.
3.UsetheMMCcommandregister(MMCCMD)tosendtheSET_BLOCKLENcommand(iftheblock
lengthisdifferentthanthelengthusedinthepreviousoperation).Theblocklengthmustbeamultiple
of512bytesandlessthenthemaximumblocklengthspecifiedintheCSD.
4.ResettheFIFO(FIFORSTbitinMMCFIFOCTL).
5.SettheFIFOdirectiontoreceive(FIFODIRbitinMMCFIFOCTL).
6.SettheFIFOthreshold(FIFOLEVbitinMMCFIFOCTL).
7.Settheaccesswidth(ACCWDbitsinMMCFIFOCTL).
8.SetupDMA(DMAsizeneedstobegreaterthanorequaltoFIFOLEVsetting).
9.UseMMCCMDtosendtheREAD_MULTI_BLOCKcommandtothecard.
10.WaitforDMAsequencetocomplete.
11.UsetheMMCstatusregister0(MMCST0)tocheckforerrors.
12.UseMMCCMDtosendtheSTOP_TRANSMISSIONcommand.
SPRUE30B–September2006MultimediaCard(MMC)/SecureDigital(SD)CardController39
SubmitDocumentationFeedback