MC2GH256NMCA-2SA00 SAMSUNG [Samsung semiconductor], MC2GH256NMCA-2SA00 Datasheet - Page 58

• Manufacturer Part Number: MC2GH256NMCA-2SA00
• Description: SAMSUNG MultiMediaCard
• Manufacturer: SAMSUNG [Samsung semiconductor]

6.7 Commands
6.7.1 Command Types
There are four kinds of commands defined to control the MultiMediaCard:
6.7.2 Command Format
All commands have a fixed code length of 48 bits, needing a transmission time of 0.92 microSec @ 52 MHz
A command always starts with a start bit (always ‘0’), followed by the bit indicating the direction of transmission (host = ‘1’).
The next 6 bits indicate the index of the command, this value being interpreted as a binary coded number (between 0 and
63). Some commands need an argument (e.g. an address), which is coded by 32 bits. A value denoted by ‘x’ in the table
above indicates this variable is dependent on the command. All commands are protected by a CRC (see Chapter 6.4 for
the definition of CRC7). Every command codeword is terminated by the end bit (always ‘1’). All commands and their argu-
ments are listed in Table 6-9 -Table 6-17.
6.7.3 Command Classes
The command set of the MultiMediaCard system is divided into several classes (See Table 6-8). Each class supports a
subset of card functions.
Class 0 is mandatory and shall be supported by all cards. The other classes are either mandatory only for specific card
types or optional. 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.
Revision 0.3
Bit position
Width (bits)
Description
* broadcast commands (bc), no response
* broadcast commands with response (bcr)
* addressed (point-to-point) commands (ac), no data transfer on DAT lines
* addressed (point-to-point) data transfer commands (adtc), data transfer on DAT lines
* All commands and responses are sent over the CMD line of the MultiMediaCard bus. The command transmission
always starts with the left bit of the bitstring corresponding to the command codeword.
Value
start bit
47
‘0’
1
transmission bit
46
‘1’
1
Table 6-7 : Format (0.92us @52MHz)
command index
[45:40]
58
6
x
argument
[39:8]
32
x
MultiMediaCard
CRC7
[7:1]
7
x
Sep.22.2005
end bit
‘1’
0
1
TM