Renesas SH7781 - Manual (Page 1239)

24. Multimedia Card Interface (MMCIF)
Rev.1.00 Jan. 10, 2008 Page 1209 of 1658
REJ09B0261-0100
24.4 Operation
The multimedia card is an external storage media that can be easily connected or disconnected.
The MMCIF operates in MMC mode.
Insert a card and supply power to it. Then operate the MMCIF by applying the transfer clock after
setting an appropriate transfer clock frequency.
Do not connect or disconnect the card during command sequence execution or in the data busy
state.
24.4.1 Operations in MMC Mode
MMC mode is an operating mode in which the transfer clock is output from the MMCCLK pin,
command transmission/response receive occurs via the MMCCMD pin, and data is
transmitted/received via the MMCDAT pin. In this mode the next command can be issued while
data is being transmitted/received.
This feature is efficient for multiple block or stream transfer. In this case, the next command is the
CMD12 command, which aborts the current command sequence.
In MMC mode, broadcast commands that simultaneously issue commands to multiple cards are
supported. After information of the inserted cards is recognized by a broadcast command, a
relative address is given to each card. One card is selected by the relative address, other cards are
deselected, and then various commands are issued to the selected card.
Commands in MMC mode are basically classified into three types: broadcast, relative address, and
flash memory operation commands. The card can be operated by issuing these commands
appropriately according to the card state.