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.
26
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.
26
Refer to “SD Memory Card Security Specification” for detailed explanation about the SD Security Features.