Secure digital input/output interface (SDIO) RM0008
589/1128 DocID13902 Rev 15
The bus transaction for a GEN_CMD is the same as the single-block read or write
commands (WRITE_BLOCK, CMD24 or READ_SINGLE_BLOCK,CMD17). In this case, the
argument denotes the direction of the data transfer rather than the address, and the data
block has vendor-specific format and meaning.
The card must be selected (in transfer state) before sending GEN_CMD (CMD56). The data
block size is defined by SET_BLOCKLEN (CMD16). The response to GEN_CMD (CMD56)
is in R1b format.
Command types
Both application-specific and general commands are divided into the four following types:
• broadcast command (BC): sent to all cards; no responses returned.
• broadcast command with response (BCR): sent to all cards; responses received
from all cards simultaneously.
• addressed (point-to-point) command (AC): sent to the card that is selected; does
not include a data transfer on the SDIO_D line(s).
• addressed (point-to-point) data transfer command (ADTC): sent to the card that is
selected; includes a data transfer on the SDIO_D line(s).
Command formats
See Table 138 on page 564 for command formats.
Commands for the MultiMediaCard/SD module
Table 154. Block-oriented write commands
CMD
index
Type Argument
Response
format
Abbreviation Description
CMD23 ac
[31:16] set to 0
[15:0] number
of blocks
R1 SET_BLOCK_COUNT
Defines the number of blocks which
are going to be transferred in the
multiple-block read or write command
that follows.
CMD24 adtc
[31:0] data
address
R1 WRITE_BLOCK
Writes a block of the size selected by
the SET_BLOCKLEN command.
CMD25 adtc
[31:0] data
address
R1 WRITE_MULTIPLE_BLOCK
Continuously writes blocks of data
until a STOP_TRANSMISSION
follows or the requested number of
blocks has been received.
CMD26 adtc [31:0] stuff bits R1 PROGRAM_CID
Programming of the card identification
register. This command must be
issued only once per card. The card
contains hardware to prevent this
operation after the first programming.
Normally this command is reserved
for manufacturer.
CMD27 adtc [31:0] stuff bits R1 PROGRAM_CSD
Programming of the programmable
bits of the CSD.
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