AT89C5132
16.2.3
Command Token Format
As shown in Figure 16-6, commands have a fixed code length of 48 Bits. Each command token
is preceded by a Start bit: a low level on MCMD line and succeeded by an End bit: a high level
on MCMD line. The command content is preceded by a Transmission bit: a high level on MCMD
line for a command token (host to card) and succeeded by a 7-bit CRC so that transmission
errors can be detected and the operation may be repeated.
Command content contains the command index and address information or parameters.
Figure 16-6. Command Token Format
0
1
Content
CRC
1
Total Length = 48 Bits
Table 71. Command Token Format
Bit Position
Width (Bits)
Value
47
1
46
1
45:40
39:8
32
-
7:1
7
0
1
6
-
‘0’
‘1’
-
‘1’
Transmission
bit
Command
Index
Start bit
Argument
CRC7
End bit
Description
16.2.4
Response Token Format
There are five types of response tokens (R1 to R5). As shown in Figure 16-7, responses have a
code length of 48 Bits or 136 Bits. A response token is preceded by a Start bit: a low level on
MCMD line and succeeded by an End bit: a high level on MCMD line. The command content is
preceded by a Transmission bit: a low level on MCMD line for a response token (card to host)
and succeeded (R1,R2,R4,R5) or not (R3) by a 7-bit CRC.
Response content contains mirrored command and status information (R1 response), CID regis-
ter or CSD register (R2 response), OCR register (R3 response), or RCA register (R4 and R5
response).
Figure 16-7. Response Token Format
R1, R4, R5
0
0
0
0
0
0
Content
CRC
1
1
Total Length = 48 Bits
R3
R2
Content
Total Length = 48 Bits
Content = CID or CSD
Total Length = 136 Bits
CRC
1
85
4173E–USB–09/07
ATMEL [ ATMEL ]
