DocID018909 Rev 11
RM0090
Secure digital input/output interface (SDIO)
1067
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. The card indicates that an erase
is in progress by holding MCDAT low. The actual erase time may be quite long, and the host
may issue CMD7 to deselect the card.
31.5.4 R3
(OCR
register)
Code length: 48 bits. The contents of the OCR register are sent as a response to CMD1.
The level coding is as follows: restricted voltage windows = low, card busy = low.
31.5.5
R4 (Fast I/O)
Code length: 48 bits. The argument field contains the RCA of the addressed card, the
register address to be read from or written to, and its content.
Table 173. R2 response
Bit position
Width (bits
Value
Description
135
1
0
Start bit
134
1
0
Transmission bit
[133:128]
6
‘111111’
Command index
[127:1]
127
X
Card status
0
1
1
End bit
Table 174. R3 response
Bit position
Width (bits
Value
Description
47
1
0
Start bit
46
1
0
Transmission bit
[45:40]
6
‘111111’
Reserved
[39:8]
32
X
OCR register
[7:1]
7
‘1111111’
Reserved
0
1
1
End bit
Table 175. R4 response
Bit position
Width (bits
Value
Description
47
1
0
Start bit
46
1
0
Transmission bit
[45:40]
6
‘100111’
CMD39
[39:8] Argument field
[31:16]
16
X
RCA
[15:8]
8
X
register address
[7:0]
8
X
read register contents