MC56U032DCCA Datasheet, PDF (48/64 Pages) Samsung semiconductor – Dual Voltage MultiMediaCard Specification

MultiMediaCard^TM
- The selected card always responds to the command.
- An additional (8 bit) response structure is used
- When the card encounters a data retrieval problem, it will respond with an error response
(which replaces the expected data block) rather than by a time-out as in the MultiMediaCard mode.
Only single block read write operations are supported in SPI mode. In addition to the command
response, every data block sent to the card during write operations will be responded with a special
data response token. A data block may be as big as one card sector and as small as a single byte.
4.10.1 Mode Selection
The MultiMediaCard wakes up in the MultiMediaCard mode. It will enter SPI mode if the CS signal is
asserted (negative) during the reception of the reset command (CMD0). If the card recognizes that the
MultiMediaCard mode is required it will not respond to the command and remain in the MultiMediaCard
mode. If SPI mode is required the card will switch to SPI and respond with the SPI mode R1 response.
The only way to return to the MultiMediaCard mode is by entering the power cycle. In SPI mode the
MultiMediaCard protocol state machine is not observed. All the MultiMediaCard commands supported
in SPI mode are always available.
4.10.2 Bus Transfer Protection
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
receiver. The SPI interface is initialized in the non protected mode. The host can turn this option on
and off using the CRC_ON_OFF command (CMD59).
4.10.3 Data Read Overview
The SPI mode supports single and multiple block read operations (CMD17 and CMD18 in the
MultiMediaCard protocol). The main difference SPI and MultiMediaCard modes is that the data and the
response are both transmitted to the host on the DataOut signal. Therefore the card response to the
STOP_COMMAND may cut-short and replace the last data block (refer to Figure “Read Operation”).
Figure 4-4 Single Block Read Operation
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