MultiMediaCard Controller

the bidirectional MMDAT signal. A typical MMC mode command timing diagram with and without a response is shown in Figure 15-2while Figure 15-3shows a typical MMC mode timing diagram for a sequential read or write

.

Figure 15-2. MMC Mode Operation Without Data Token

from host to card(s)

MMCMD

Command

from host to card

from card to host

Command Response

MMDAT

Operation (No Response)

Operation (No Data)

Figure 15-3. MMC Mode Operation With Data Token

from

from

 

stop command

host to

 

data to/from

 

stops data transfer

 

 

 

MMCMD

Command

Response

Command

Response

MMDAT

Data Stream

Data Transfer Operation

Data Stop Operation

In SPI mode, not all commands are available. The available commands have both a command and response token. The MMCMD and MMDAT signals are no longer bidirectional in SPI mode. The MMCMD is an output and the MMDAT is an input with respect to the processor. The command and data tokens to be written are sent on the MMCMD signal and the response and read data tokens are received on the MMDAT signal. Figure 15-4shows a typical SPI mode timing diagram without a data token. Figure 15-5and Figure 15-6show SPI mode read and write timing diagrams, respectively.

Intel® PXA255 Processor Developer’s Manual

15-3

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Intel PXA255 manual Mmcmd, Mmdat