R4 (Fast I/O); R4B; Table 162. R3 Response; Table 163. R4 Response - ST STM32F101 series Reference Manual

Secure digital input/output interface (SDIO)
Bit position
47
46
[45:40]
[39:8]
[7:1]
0
22.5.5

R4 (Fast I/O)

Code length: 48 bits. The argument field contains the RCA of the addressed card, the
register address to be read out or written to, and its content.
47
46
[45:40]
[39:8] Argument field
[7:1]
0
22.5.6

R4b

For SD I/O only: an SDIO card receiving the CMD5 will respond with a unique SDIO
response R4. The format is:
47
46
[45:40]
[39:8] Argument field
593/1128
Width (bits
1
1
6
32
7
1
Bit position
[31:16]
[15:8]
[7:0]
Bit position
39
[38:36]
35
[34:32]
[31:8]
DocID13902 Rev 15

Table 162. R3 response

Value
0
0
'111111'
X
'1111111'
1

Table 163. R4 response

Width (bits
1 0
1 0
6 '100111'
16 X
8 X
8 X
7 X
1 1

Table 164. R4b response

Width (bits
1 0
1 0
6 X
16 X
3 X
1 X
3 X
24 X
Description
Start bit
Transmission bit
Reserved
OCR register
Reserved
End bit
Value Description
Start bit
Transmission bit
CMD39
RCA
register address
read register contents
CRC7
End bit
Value Description
Start bit
Transmission bit
Reserved
Card is ready
Number of I/O functions
Present memory
Stuff bits
I/O ORC
RM0008