MC2GH256NMCA-2SA00 SAMSUNG [Samsung semiconductor], MC2GH256NMCA-2SA00 Datasheet - Page 82

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

Every MultiMediaCard token transferred on the bus is protected by CRC bits. In SPI mode, the MultiMediaCard offers a
non-protected mode which enables systems built with reliable data links to exclude the hardware or firmware required for
implementing the CRC generation and verification functions. In the non-protected mode, the CRC bits of the command,
response and data tokens are still required in the tokens. However, they are defined as ‘don’t care’ for the transmitter and
ignored by the receiver.
The SPI interface is initialized in the non-protected mode. However, the RESET command (CMD0), which is used to
switch the card to SPI mode, is received by the card while in MultiMediaCard mode and, therefore, must have a valid CRC
field.
Since CMD0 has no arguments, the content of all the fields, including the CRC field, are constants and need not be calcu-
lated in run time. A valid reset command is:
The host can turn the CRC option on and off using the CRC_ON_OFF command (CMD59).
The SPI mode supports single and multiple block read operations. The main difference between SPI and MultiMediaCard
modes is that the data and the response are both transmitted to the host on the DataOut signal (refer to Figure 7-2 and
Figure 7-3). Therefore the card response to the STOP_COMMAND may cut-short and replace the last data block.
7.6 Bus Transfer Protection
7.7 Data Read
Revision 0.3
DataIn
DataOut
0x40, 0x0, 0x0, 0x0, 0x0, 0x95
to card
from
host
DataIn
DataOut
command
to card
from
host
command
Figure 7-3 : SPI Multiple Block Read Operation
response
Figure 7-2 : SPI Single Block Read Operation
to host
from
card
response
data block
to host
data from card
from
card
82
to host
data block
CRC
data from card
to host
data block CRC
CRC
Command
Command
Next
Stop
command
command
MultiMediaCard
data B.
Sep.22.2005
response
TM