ST STM32L4+ Series Reference Manual page 1974

Secure digital input/output MultiMediaCard interface (SDMMC)
coding schemes, depending on their content. The general formats for the response tokens
for SD-Memory cards, SDIO cards, and e•MMC cards are shown in
and Table
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. Most responses, except some, are protected by a CRC. Every command
code word is terminated by the End bit (always 1).
The Response token data is stored in 5 registers, four containing the 32-bits card status,
OCR register, argument or 127-bits CID or CSD register including internal CRC, and one
register containing the 6-bits command index.
Bit position
47
46
[45:40]
[39:8]
[7:1]
0
Bit position
47
46
[45:40]
[39:8]
[7:1]
0
Bit position
135
134
[133:128]
[127:1]
0
The Command/Response path operates in a half-duplex mode, so that either commands
can be sent or responses can be received. If the CPSM is not in the Send state, the
1974/2301
391.
Table 389. Short response with CRC token format
Width
1
1
6
32
7
1
Table 390. Short response without CRC token format
Width
1
1
6
32
7
1
Table 391. Long response with CRC token format
Width
1
1
6
127:8
7:1
1
Value
0 Start bit
0 Transmission bit
x Command index (or reserved 111111)
x Argument
x CRC7
1 End bit
Value
0 Start bit
0 Transmission bit
x Command index (or reserved 111111)
x Argument
1111111 (reserved 1111111)
1 End bit
Value
0 Start bit
0 Transmission bit
111111 Reserved
x CID or CSD slices
x CRC7 (included in CID or CSD)
1 End bit
RM0432 Rev 6
RM0432
Table 389, Table 390
Description
Description
Description