Table 221. Short Response Format; Table 222. Long Response Format; Table 223. Command Path Status Flags - ST STM32L4x6 Reference Manual

SD/SDIO/MMC card host interface (SDMMC)
Bit position
47
46
[45:40]
[39:8]
[7:1]
0
Bit position
135
134
[133:128]
[127:1]
0
The command register contains the command index (six bits sent to a card) and the
command type. These determine whether the command requires a response, and whether
the response is 48 or 136 bits long (see
implements the status flags shown in
Flag
CMDREND
CCRCFAIL
CMDSENT
CTIMEOUT
CMDACT
The CRC generator calculates the CRC checksum for all bits before the CRC code. This
includes the start bit, transmitter bit, command index, and command argument (or card
status). The CRC checksum is calculated for the first 120 bits of CID or CSD for the long
response format. Note that the start bit, transmitter bit and the six reserved bits are not used
in the CRC calculation.
The CRC checksum is a 7-bit value:
CRC[6:0] = Remainder [(M(x) * x
G(x) = x
M(x) = (start bit) * x
M(x) = (start bit) * x
1402/1693

Table 221. Short response format

Width
1
1
6
32
7
1

Table 222. Long response format

Width
1
1
6
127
1

Table 223. Command path status flags

Description
Set if response CRC is OK.
Set if response CRC fails.
Set when command (that does not require response) is sent
Response timeout.
Command transfer in progress.
7 3
+ x + 1
39
+ ... + (last bit before CRC) * x
119
+ ... + (last bit before CRC) * x
DocID024597 Rev 3
Value
0
0
-
-
-
1
Value
0 Start bit
0 Transmission bit
111111 Reserved
- CID or CSD (including internal CRC7)
1 End bit
Section 41.8.4 on page
Table 223:
7
) / G(x)]
0
, or
0
RM0351
Description
Start bit
Transmission bit
Command index
Argument
CRC7(or 1111111)
End bit
Description
1437). The command path