Secure digital input/output interface (SDIO)
RM0090
1046/1731
DocID018909 Rev 11
31.5 Response
formats
All responses are sent via the MCCMD command line SDIO_CMD. The response
transmission always starts with the left bit of the bit string corresponding to the response
code word. The code length depends on the response type.
A response always starts with a start bit (always 0), followed by the bit indicating the
direction of transmission (card = 0). A value denoted by x in the tables below indicates a
variable entry. All responses, except for the R3 response type, are protected by a CRC.
Every command code word is terminated by the end bit (always 1).
There are five types of responses. Their formats are defined as follows:
31.5.1
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.
31.5.2 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.
31.5.3
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
CMD57
...
CMD59
Reserved.
CMD60
...
CMD63
Reserved for manufacturer.
Table 171. Application-specific commands (continued)
CMD
index
Type
Argument
Response
format
Abbreviation
Description
Table 172. R1 response
Bit position
Width (bits
Value
Description
47
1
0
Start bit
46
1
0
Transmission bit
[45:40]
6
X
Command index
[39:8]
32
X
Card status
[7:1]
7
X
CRC7
0
1
1
End bit