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GD32F403xx User Manual
521
R2 (CID, CSD register)
Code length is 136 bits. The contents of the CID register are sent as a response to the
commands CMD2 and CMD10. The contents of the CSD register are sent as a response to
CMD9. Only the bits [127..1] of the CID and CSD are transferred, the reserved bit [0] of these
registers is replaced by the end bit of the response.
Table 20-15. Response R2
Bit position
135
134
[133:128]
[127:1]
0
Width
1
1
6
127
1
Value
‘0’
‘0’
‘111111’
x
‘1’
description
start bit
transmission
bit
reserved
CID or CSD
register and
internal
CRC7
end bit
R3 (OCR register)
Code length is 48 bits. The contents of the OCR register are sent as a response to ACMD41
(SD memory), CMD1 (MMC). The response of different cards may have a little different.
Table 20-16. Response R3
Bit position
47
46
[45:40]
[39:8]
[7:1]
0
Width
1
1
6
32
7
1
Value
‘0’
‘0’
‘111111’
x
‘1111111’
‘1’
description
start bit
transmission
bit
reserved
OCR
register
reserved
end bit
R4 (Fast I/O)
For MMC only. Code length 48 is bits. The argument field contains the RCA of the addressed
card, the register address to be read out or written to, and its contents. The status bit in the
argument is set if the operation was successful.
Table 20-17. Response R4 for MMC
Bit position
47
46
[45:40]
[39:8] Argument field
[7:1]
0
Width
1
1
6
16
1
7
8
7
1
Value
‘0’
‘0’
‘100111’
x
x
x
x
x
‘1’
description
start
bit
transmission
bit
CMD39
RCA
[31:16]
status
[15]
register
address
[14:8]
read
register
contents
[7:0]
CRC7
end
bit
R4b
For SD I/O only. Code length is 48 bits. The SDIO card receive the CMD5 will respond with a