GD32F403xx User Manual
523
Value
‘0’
‘0’
‘000011’
x
x
x
‘1’
description
start
bit
transmission
bit
CMD3
New published RCA
of the card
card
status
bits:23,22,19,12:0
CRC7
end
bit
R7 (Card interface condition)
For SD memory only. Code length is 48 bits. The card support voltage information is sent by
the response of CMD8. Bits 19-16 indicate the voltage range that the card supports. The card
that accepted the supplied voltage returns R7 response. In the response, the card echoes
back both the voltage range and check pattern set in the argument.
Table 20-22. Response R7
Bit position
47
46
[45:40]
[39:20]
[19:16]
[15:8]
[7:1]
0
Width
1
1
6
20
4
8
7
1
Value
‘0’
‘0’
‘001000’
‘00000h’
x
x
x
‘1’
description
start
bit
transmission
bit
CMD8
Reserved
bits
Voltage
accepted
echo-back of
check pattern
CRC7
end
bit
20.5.4.
Data packets format
There are 3 data bus mode, 1-bit, 4-bit and 8-bit width. 1-bit mode is mandatory, 4-bit and 8-
bit mode is optional. Although using 1-bit mode, DAT3 also need to notify card current working
mode is SDIO or SPI, when card reset and initialize.
1-bit data packet format
After card reset and initialize, only DAT0 pin is used to transfer data. And other pin can be
used freely.
Figure 20-9. 1-bit data bus width
Figure 20-10. 4-bit data bus width
and
Figure 20-11. 8-bit data bus width
show the data packet format when data bus wide is 1-bit,
4-bit and 8-bit.
Figure 20-9. 1-bit data bus width
0
CRC
1
1
st
Byte
2
nd
Byte
3
rd
Byte
…
…
n
th
Byte
Start
bit
End
bit
b7
b6
b5
b4
b3
b2
b1
b0
b7
b6
b5
b4
b3
b2
b1
b0
DAT0