R1 (Normal Response Command); R1B; R2 (Cid, Csd Register); Table 151. R1 Response - ST STM32F40 Series Reference Manual

Secure digital input/output interface (SDIO)
28.5.1

R1 (normal response command)

Code length = 48 bits. The 45:40 bits indicate the index of the command to be responded to,
this value being interpreted as a binary-coded number (between 0 and 63). The status of the
card is coded in 32 bits.

Table 151. R1 response

Bit position
47
46
[45:40]
[39:8]
[7:1]
0
28.5.2

R1b

It is identical to R1 with an optional busy signal transmitted on the data line. The card may
become busy after receiving these commands based on its state prior to the command
reception.
28.5.3

R2 (CID, CSD register)

Code length = 136 bits. The contents of the CID register are sent as a response to the
CMD2 and CMD10 commands. 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. 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.

Table 152. R2 response

Bit position
135
134
[133:128]
[127:1]
0
881/1422
Width (bits
1 0
1 0
6 X
32 X
7 X
1 1
Width (bits
1 0
1 0
6 '111111'
127 X
1 1
Doc ID 018909 Rev 4
Value
Start bit
Transmission bit
Command index
Card status
CRC7
End bit
Value
Start bit
Transmission bit
Command index
Card status
End bit
RM0090
Description
Description