Chapter 4 – SD Card Protocol Description
Revision 2.2 SanDisk SD Card Product Manual
© 2004 SanDisk Corporation 4-37 12/08/04
CMD Index Type Argument Resp. Abbreviation Description
CMD57
Application-Specific Commands
All future reserved commands will have a codeword length of 48 bits, as well as their
responses (if there are any).
The following table describes all application-specific commands supported or reserved by
the SD Card. All the following ACMDs will be preceded with the APP_CMD command
(CMD55).
Table 4-17 Application-specific Commands
ACMD Index Type Argument Resp. Abbreviation Command Description
ACMD6 ac [31:2] stuff
bits [1:0]
bus width
R1 SET_BUS_WIDTH Defines the data bus
width (’00’=1bit or’10’=4
bits bus) to be used for
data transfer. The
allowed data bus widths
are given in SCR register.
ACMD13 adtc [31:0] stuff
bits
R1 SD_STATUS Send the SD Memory
Card status.
ACMD17 Reserved
ACMD18 --- --- --- --- Reserved for SD security
applications.
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ACMD19 to
ACMD21
Reserved
ACMD22 adtc [31:0] stuff
bits
R1 SEND_NUM_WR_BLOCKS Send the number of the
written (without errors)
write blocks. Responds
with 32bit+CRC data
block. If
WRITE_BL_PARTIAL='0',
the unit of ACMD22 is
always 512byte. If
WRITE_BL_PARTIAL='1',
the unit of ACMD22 is a
block length which was
used when the write
command was executed.
ACMD24 Reserved
ACMD25 --- --- --- --- Reserved for SD security
applications.
ACMD26 --- --- --- --- Reserved for SD security
applications.
ACMD38 --- --- --- --- Reserved for SD security
applications.
ACMD39 to
ACMD40
Reserved
ACMD41 bcr [31:0]
OCR
w/out busy
R3 SD_SEND_OP_COND Asks the accessed card
to send its operating
condition register (OCR)
content in the response
on the CMD line.
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Refer to “SD Memory Card Security Specification” for detailed explanation about the SD Security Features.
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