474
/
838
Nations Technologies Inc.
Tel
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Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
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command is not an ACMD command, the card will be processed according to the ordinary multimedia card
command, At the same time, clear the APP_CMD bit of the status register.
If an illegal command is sent, error handling will be performed according to standard illegal multimedia card
commands. The bus operation process of the GEN_CMD command is the same as the single data block read and
write command (WRITE_BLOCK, CMD24 or READ_SINGLE_BLOCK, CMD17); at this time, the parameter of
the command indicates the direction of data transmission instead of the address, and the data block has a user-defined
format and meaning.
Before sending the GEN_CMD (CMD56) command, the state machine must be in the transmission state, that is, the
card must be selected, and the length of the data block is defined by SET_BLOCKLEN (CMD16). The response to
the GEN_CMD (CMD56) command is in R1b format.
18.5.2
Commands of Multimedia Card/SD Card module
Table 18-16 Write commands for block-based transfers
CMD
Index
Type
Parameter
Response
Format
Abbreviation
Description
CMD23
ac
[31:16]=0
[15:0]= Number of
blocks
R1
SET_BLOCK_COUNT
Defines the number of blocks that need
to be transferred in a subsequent multi-
block read or write command.
CMD24
adtc
[31:0]= Data Address
R1
WRITE_BLOCK
Writes a block of the length selected by
the SET_BLOCKLEN command.
CMD25
adtc
[31:0]= Data Address
R1
WRITE_MULTIPLE_BLOCK
Continuously write data blocks until a
STOP_TRANSMISSION command is
received or the specified number of
blocks is reached.
CMD26
adtc
[31:0]= Stuff bits
R1
PROGRAM_CID
Program the identification register of the
card. This command can only be sent
once per card. There are hardware
mechanisms in the card to prevent
multiple programming operations.
Usually this order is reserved for the
manufacturer.
CMD27
adtc
[31:0]= Stuff bits
R1
PROGRAM_CSD
Program the programmable bits in the
CSD of the card.
CMD28
ac
[31:0]= Data Address
R1b
SET_WRITE_PROT
If the card is write-protected, this
command sets the write-protect bit of
the specified group. The write protection
feature is set in the special data area of
the card (WP_GRP_SIZE).
CMD29
ac
[31:0]= Data Address
R1b
CLR_WRITE_PROT
If the card is write-protected, this
command clears the write-protect bit of
the specified group.