Specifications
©Copyright 2001-2013 SD Group (Panasonic, SanDisk, Toshiba) and SD Card Association
Physical Layer Simplified Specification Version 4.10
80
4.9 Responses
All responses are sent via the command line CMD. The response transmission always starts with the
left bit of the bit string corresponding to the response codeword. 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 the type R3 (see below) are protected by a CRC (see Chapter 4.5 for the definition of
CRC7). Every command codeword is terminated by the end bit (always 1).
There are five types of responses for the SD Memory Card. The SDIO Card supports additional
response types named R4 and R5. Refer to SDIO Card Spec for detailed information on the SDIO
commands and responses. Their formats are defined as follows:
4.9.1 R1 (normal response command):
Code length is 48 bits. The bits 45:40 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. Note that if a data transfer to the card is involved, then a busy signal may appear on the data line
after the transmission of each block of data. The host shall check for busy after data block transmission.
The card status is described in Chapter 4.10
.
Bit position
47
46
[45:40]
[39:8]
[7:1]
0
Width (bits)
1
1
6
32
7
1
Value
'0'
'0'
x
x
x
'1'
Description start bit
transmission
bit
command index card status CRC7 end bit
Table 4-35: Response R1
4.9.2 R1b
R1b 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. The Host shall
check for busy at the response.
4.9.3 R2 (CID, CSD register)
Code length is 136 bits. The contents of the CID register are sent as a response to the commands
CMD2 and CMD10. The contents of the CSD register are sent as a response to CMD9. Only the bits
[127...1] of the CID and CSD are transferred, the reserved bit [0] of these registers is replaced by the
end bit of the response.
Bit position
135
134
[133:128]
[127:1]
0
Width (bits)
1
1
6
127
1
Value
'0'
'0'
'111111'
x
'1'
Description start bit
transmission
bit
reserved
CID or CSD register incl.
internal CRC7
end bit
Table 4-36: Response R2