Revision 1.0 MultiMediaCardRS-MultiMediaCard Product Manual
© 2004 SanDisk Corporation 5-7
051304
is reselected before the programming has finished, the dataOut line will be forced back to low and all commands will be rejected.
Resetting a card using CMD0 will terminate any pending or active programming operation. However, this may destroy data formats on the card. It is the host’s responsibility
to prevent that from happening.
5.9 Erase and Write Protect Management
Erase and Write Protect Management procedures in SPI Mode and MultiMediaCard mode are identical. When the card is erasing or changing the write protection bits of the
predefined write-protect group list, it will be in a busy state and hold the dataOut line low. Figure 5-11 illustrates a “no data” bus transaction with and without busy signaling.
Figure 5-11 No Data Operations
5.10 Read CIDCSD Registers
Unlike MultiMediaCard Protocol where the register contents are sent as a command response, SPI Mode provides a simple read block transaction for reading the contents of the
CSD and CID registers. The card will respond with a standard response token followed by a data block of 16 bytes, suffixed with a 16-bit CRC.
The data timeout for the CSD command cannot be set to the card TAAC because its value is stored in the CSD. Therefore, the standard response timeout value N
CR
is used for read latency of the CSD register.
5.11 Reset Sequence
The MultiMediaCardRS-MultiMediaCard requires a defined reset sequence. After power- on reset or software reset CMD0, the card enters an idle state. In this state, the only legal
host commands are CMD1 SEND_OP_COND and CMD58 READ_OCR.
The host must poll the card by repeatedly sending CMD1 until the “in-idle-state” bit in the card response indicates, by being set to 0, that the card completed its initialization
processes and is ready for the next command.
However, in SPI mode, CMD1 has no operands and does not return the contents of the OCR Register. Instead, the host can use CMD58 SPI Mode Only to read the register. It is
the responsibility of the host to refrain from accessing cards that do not support its voltage range.
The use of CMD58 is not restricted to the initialization phase only, but can be issued at any time. The host must poll the card by repeatedly sending CMD1 until the “in-idle-state” bit
Command DataIn
Response From Host
to Card From Host
to Card
DataOut Command
Response Busy
From Card to Host
From Card to Host
Revision 1.0 MultiMediaCardRS-MultiMediaCard Product Manual
© 2004 SanDisk Corporation 5-8
051304
in the card response indicates, by being set to 0, that the card has completed its initialization process and is ready for the next command.
5.12 Clock Control
