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MultiMediaCard Product Manual
5.7.2
Command Format
(Command length 48 bits, 2.4 s @ 20 MHz)
0
1
start bit
host
Commands and arguments are listed in Table 5-3 through Table 5-9.
7-bit CRC Calculation: G(x) = x
39
M(x) = (start bit) x
+ (host bit) x
CRC[6...0] = Remainder[(M(x) x
5.7.3
Command Classes
The command set of the MultiMediaCard is divided into several classes (See Table 5-2). Each class
supports a set of MultiMediaCard functions.
The supported Card Command Classes (CCC) are coded as a parameter in the card specific data (CSD)
register of each card, providing the host with information on how to access the card.
Table 5-2 Card Command Classes (CCCs)
Card
Command
Class (CCC)
Class 0
Class 1
Class 2
Class 3
Class 4
Class 5
Class 6
Class 7
Class 8
Class 9
Class 10-11
1)
7-bit Cyclic Redundancy Check.
2)
I/O mode class is not supported by the SanDisk MultiMediaCard.
48
bit 5...bit 0
bit 31...bit 0
command
7 +
3 +
x
1
38
+...+ (last bit before CRC) x
7
)/G(x)]
Class Description
Basic
Stream Read
Block Read
Stream Write
Block Write
Erase
Write Write-Protection
Read Write-Protection
Erase Write-Protection
2
I/O Mode
Reserved
SanDisk MultiMediaCard Product Manual Rev. 2 © 2000 SANDISK CORPORATION
bit 6...bit 0
argument
0
Supported Commands
0 1
2 3 4
7 9 10 11 12 13 15 16 17 18 20
+ +
+ + +
+ +
+
1
1
CRC7
end bit
+
+ +
+
+ + +
+
+
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