MultiMediaCardTM
4.6 MultiMediaCard Communication
All communication between host and cards is controlled by the host (master). The host sends
commands and, depending on the command, receives a corresponding response from the selected
card. In this chapter the commands to control the MultiMediaCard, the card responses and the
contents of the status and error field included in the responses, are defined.
4.6.1 Commands
The command set of the MultiMediaCard system is divided into classes corresponding to the type of
card. The MultiMediaCard supports the following command classes:
Table 4-8 Command Classes
Class
Command
0
Class Description
1
2
3
4
Class 0
Basic
7
9
10
12
13
15
11
16
17
18
20
24
25
26
27
32
33
34
35
36
37
38
28
29
30
42
Calss 1
Class 2
Class 3
Stream read (not supported)
Block read
Stream write (not supported)
Class 4
Block write
Erase
Class 5
(not supported CMD 32~34 and 37 according to
MMC system spec 3.31)
Class 6
Class 7
Write protection
Lock card
30
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