Secure digital input/output interface (SDIO)
RM0090
1048/1731
DocID018909 Rev 11
31.5.6 R4b
For SD I/O only: an SDIO card receiving the CMD5 will respond with a unique SDIO
response R4. The format is:
Once an SD I/O card has received a CMD5, the I/O portion of that card is enabled to
respond normally to all further commands. This I/O enable of the function within the I/O card
will remain set until a reset, power cycle or CMD52 with write to I/O reset is received by the
card. Note that an SD memory-only card may respond to a CMD5. The proper response for
a memory-only card would be
Present
memory
= 1 and
Number of I/O functions
= 0. A
memory-only card built to meet the SD Memory Card specification version 1.0 would detect
the CMD5 as an illegal command and not respond. The I/O aware host will send CMD5. If
the card responds with response R4, the host determines the card’s configuration based on
the data contained within the R4 response.
31.5.7
R5 (interrupt request)
Only for MultiMediaCard. Code length: 48 bits. If the response is generated by the host, the
RCA field in the argument will be 0x0.
[7:1]
7
X
CRC7
0
1
1
End bit
Table 175. R4 response (continued)
Bit position
Width (bits
Value
Description
Table 176. R4b response
Bit position
Width (bits
Value
Description
47
1
0
Start bit
46
1
0
Transmission bit
[45:40]
6
x
Reserved
[39:8] Argument field
39
16
X
Card is ready
[38:36]
3
X
Number of I/O functions
35
1
X
Present memory
[34:32]
3
X
Stuff bits
[31:8]
24
X
I/O ORC
[7:1]
7
X
Reserved
0
1
1
End bit
Table 177. R5 response
Bit position
Width (bits
Value
Description
47
1
0
Start bit
46
1
0
Transmission bit
[45:40]
6
‘101000’
CMD40