MultiMediaCardTM
defined. The card will continuously transfer data blocks until a stop transmission command is
received.
* Multiple block read with pre-defined block count : 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 other to start 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 this card will start an open-ended multiple block read which can be stopped using the
STOP_TRANSMISSION command.
4.9.2 Block Write
Block write (CMD24 - 27) means that one or more blocks of data are transferred from the host to the
card with a CRC appended to the end of each block by the host. A card supporting block write must
always be able to accept a block of data defined by WRITE_BLK_LEN. If the CRC fails, the card will
indicate the failure on the DAT line; the transferred data will be discarded and not written and all further
transmitted blocks (in multiple block write mode) will be ignored. The write operation will also be
aborted if the host tries to write over a write-protected area. In this case, however, the card will set the
WP_VIOLATION bit. Programming of the CID and CSD register does not require a previous block
length setting. The transferred data is also CRC protected. The MultiMediaCard write operation follows
some special rules:
WRITE_MULTIPLE_BLOCK(CMD25) starts a transfer of several consecutive blocks. Two types of
multiple block write transactions, identical to the multiple block read, are defined (the host can use
either on at any time)
* Open-ended Multiple block write : The number of blocks for the write multiple block operation is not
defined. The card will continuously accept and program data block until a stop transmission
command is received.
* Multiple block write with pre-defined block count : 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 write, unless terminated with an error. In other to start multiple
block write with pre-defined block count, the host must use the SET_BLOCK COUNT
command(CMD23) immediately preceding the WRITE_MULTIPLE_BLOCK(CMD25) command.
Otherwise this card will start an open-ended multiple block write which can be stopped using the
STOP_TRANSMISSION command.
The host can abort writing at any time, within a multiple block operation regardless of the its type.
Transaction abort is done by sending the stop transmission command. If a multiple block write with
predefined block count is aborted, the data in the remaining blocks is not defined.
4.9.3 Erase
The erasable unit is the Erase Group. Erase group is measured in write blocks which are the basic
writable units of the card. The size of the Erase group is a card specific parameter and defined in the
CSD.
The host can erase a contiguous range of Erase Groups. Starting the erase process is a three steps
sequence. First the host defines the start address of the range using the
ERASE_GROUP_START(CMD35) command, next it defines the last address of the range using the
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