Datasheet

138
4341H–MP3–10/07
AT8xC51SND2C/MP3B
Table 18-2. R1 Response Format (Normal Response)
Table 18-3. R2 Response Format (CID and CSD registers)
Table 18-4. R3 Response Format (OCR Register)
Table 18-5. R4 Response Format (Fast I/O)
Table 18-6. R5 Response Format
18.2.5 Data Packet Format
There are 2 types of data packets: stream and block. As shown in Figure 18-8, stream data
packets have an indeterminate length while block packets have a fixed length depending on the
block length. Each data packet is preceded by a Start bit: a low level on MCMD line and suc-
ceeded by an End bit: a high level on MCMD line. Due to the fact that there is no predefined end
in stream packets, CRC protection is not included in this case. The CRC protection algorithm for
block data is a 16-bit CCITT polynomial.
Bit Position 47 46 45:40 39:8 7:1 0
Width (bits) 1 1 6 32 7 1
Value ‘0’ ‘0’ - - - ‘1’
Description
Start bit Transmission bit
Command
Index
Card Status CRC7 End bit
Bit Position 135 134 [133:128] [127:1] 0
Width (bits) 1 1 6 32 1
Value ‘0’ ‘0’ ‘111111’ - ‘1’
Description Start bit Transmission bit Reserved Argument End bit
Bit Position 47 46 [45:40] [39:8] [7:1] 0
Width (bits) 1 1 6 32 7 1
Value ‘0’ ‘0’ ‘111111’ - ‘1111111’ ‘1’
Description Start bit Transmission bit Reserved OCR register Reserved End bit
Bit Position 47 46 [45:40] [39:8] [7:1] 0
Width (bits) 1 1 6 32 7 1
Value ‘0’ ‘0’ ‘100111’ - - ‘1’
Description
Start bit Transmission bit
Command
Index
Argument CRC7 End bit
Bit Position 47 46 [45:40] [39:8] [7:1] 0
Width (bits) 1 1 6 32 7 1
Value ‘0’ ‘0’ ‘101000’ - - ‘1’
Description
Start bit Transmission bit
Command
Index
Argument CRC7 End bit