Product manual

4-3 SanDisk miniSD Card Product Manual, Rev. 1.1 © 2003 SANDISK CORPORATION
Each command token is preceded by a start bit (0) and succeeded by an end bit (1). The total length is 48 bits. CRC
bits protect each token so that transmission errors can be detected and the operation may be repeated.
Response tokens have four coding schemes depending on their content. The token length is either 48 or 136 bits.
The CRC protection algorithm for block data is a 16-bit CCITT polynomial. All used CRC types are described in
Section 4.6.
Start bit
always '0'
0 0 Content 1
Response content: mirrored command and status
information (R1 response), OCR register (R3 response)
or RCA (R6) protected by 7 bit CRC checksum
Transmitter bit:
'0'=card response
Total length = 48 bits
End bt:
always '1'
0 0 Content = CID or CSD CRC 1
Total length = 136 bits
End bt:
always '1'
R1, R3, R6
R2
Figure 4-5. Response Token Format
In the CMD line, the MSB bit is transmitted first, whereas the LSB bit is transmitted last.
When the wide bus option is used, the data is transferred 4 bits at a time (see Figure 4-6). Start and end bits, as well
as the CRC bits, are transmitted for every one of the DAT lines. CRC bits are calculated and checked for every DAT
line individually. The card sends the CRC status response and Busy indication to the host on DAT0 only (DAT1-
DAT3 during that period are “don’t care”).