MC2GH256NMCA-2SA00 SAMSUNG [Samsung semiconductor], MC2GH256NMCA-2SA00 Datasheet - Page 47

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

• Block Read
Block read is similar to stream read, except the basic unit of data transfer is a block whose maximum size is defined in the
CSD (READ_BL_LEN). If READ_BL_PARTIAL is set, smaller blocks whose starting and ending address are entirely con-
tained within one physical block (as defined by READ_BL_LEN) may also be transmitted. Unlike stream read, a CRC is
appended to the end of each block ensuring data transfer integrity. CMD17 (READ_SINGLE_BLOCK) initiates a block
read and after completing the transfer, the card returns to the Transfer State.
CMD18 (READ_MULTIPLE_BLOCK) starts a transfer of several consecutive blocks. Two types of multiple block read
transactions are defined (the host can use either one at any time):
• Open-ended Multiple block read
• Multiple block read with pre-defined block count
The host can abort reading at any time, within a multiple block operation, regardless of the its type. Transaction abort is
done by sending the stop transmission command.
If either one of the following conditions occur, the card will reject the command, remain in Tran state and respond with the
respective error bit set.
• The host provides an out of range address as an argument to either CMD17 or CMD18.
• The currently defined block length is illegal for a read operation. BLOCK_LEN_ERROR is set.
• The address/block-length combination positions the first data block misaligned to the card physical blocks.
If the card detects an error (e.g. out of range, address misalignment, internal error, etc.) during a multiple block read oper-
ation (both types) it will stop data transmission and remain in the Data State. The host must then abort the operation by
sending the stop transmission command. The read error is reported in the response to the stop transmission command.
If the host sends a stop transmission command after the card transmits the last block of a multiple block operation with a
pre-defined number of blocks, it is regarded as an illegal command, since the card is no longer in data state.
If the host uses partial blocks whose accumulated length is not block aligned, and block misalignment is not allowed, the
card shall detect a block misalignment error condition during the transmission of the first misaligned block and the content
of the further transferred bits is undefined. As the host sends CMD12 the card will respond with the ADDRESS_MISALIGN
bit set and return to Tran state.
If the host sets the argument of the SET_BLOCK_COUNT command (CMD23) to all 0s, then the command is accepted;
however, a subsequent read will follow the open-ended multiple block read protocol (STOP_TRANSMISSION command -
CMD12 - is required).
Revision 0.3
-ended multiple block read which can be stopped using the STOP_TRANSMISION command.
The number of blocks for the read multiple block operation is not defined. The card will continuously transfer data
blocks until a stop transmission command is received.
The card will transfer the requested number of data blocks, terminate the transaction and return to transfer state. Stop
command is not required at the end of this type of multiple block read, unless terminated with an error. In order to start
a multiple block read with pre-defined block count the host must use the SET_BLOCK_COUNT command (CMD23)
immediately preceding the READ_MULTIPLE_BLOCK (CMD18) command. Otherwise the card will start an open
ADDRESS_OUT_OF_RANGE is set.
ADDRESS_MISALIGN is set.
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MultiMediaCard
Sep.22.2005
TM