at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 378

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Data Transfer
Operation
378
AT91RM3400
command requires a response, it can be read in the MCI response register (MCI_RSPR). The
response size can be 48 bits up to 136 bits according to the command. The MCI embeds an
error detection to prevent any corrupted data during the transfer.
The following flowchart shows how to send a command to the card and read the response if
needed. In this example, the status register bits are polled but setting the appropriate bits in
the interrupt enable register (MCI_IER) allows using an interrupt method.
Figure 158. Command/Response Functional Flow Diagram
Note:
The MultiMedia Card allows several read/write operations (single block, multiple blocks,
stream, etc.).
These operations can be done using the Peripheral Data Controller (PDC) features. If the
PDCMODE bit is set in MCI_MR, then all reads and writes use the PDC facilities. In all cases,
the block length must be defined in the mode register.
1. If the command is SEND_OP_COND, the CRC error flag is always present (refer to R3
response in the MultiMediaCard specification).
Check error bits in the
Wait for command
status register
ready status flag
(1)
Set the command argument
MCI_ARGR = Argument
Read response if required
MCI_CMDR = Command
Status error flags?
Set the command
Read MCI_SR
RETURN OK
CMDRDY
1
(1)
RETURN ERROR
Yes
0
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