MC56U032DCCA Datasheet, PDF (29/64 Pages) Samsung semiconductor – Dual Voltage MultiMediaCard Specification

MultiMediaCard^TM
Class
Class 0
Calss 1
Class 2
Class 3
Class 4
Class 5
Class 6
Class 7
Command
0
1
2
3
4
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
Class Description
Basic
Stream read (not supported)
Block read
Stream write (not supported)
Block write
Erase
(not supported CMD 32~34 and 37 according to
MMC system spec 3.31)
Write protection
Lock card
Class 0 is mandatory and supported by all cards. It represents the card identification and initialization
commands, which are intended to handle different cards and card types on the same bus lines. The
Card Command Class (CCC) is coded in the card specific data register of each card, so that the host
knows how to access the card. There are four kinds of commands defined on the MultiMediaCard bus:
- broadcast commands (bc) sent on CMD line, no response.
- broadcast commands with response (bcr) sent on CMD line, response (all cards simultaneously) on
CMD line
- addressed (point-to-point) commands (ac) sent on CMD line, response on CMD line.
- addressed (point-to-point) data transfer commands (adtc) sent on CMD line, response on CMD line,
data transfer on DAT line.
The command transmission always starts with the MSB. Each command starts with a start bit and ends
with a CRC command protection field followed by an end bit. The length of each command frame is
fixed to 48 bits (2.4 us at 20 MHz):
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