SH7760 Datasheet, PDF (998/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

(5) Commands with Read Data
Flash memory operation commands include a number of commands involving read data. Such
commands confirm the card status by the command argument and command response, and
receive card information and flash memory data from the MCDAT pin.
The number of bytes of the flash memory to be read is specified by CMD16 as a block size, or
if not specified, reading is continued until it is aborted by CMD12 during multiblock or stream
transfer. In multiblock transfer, the transfer operation is suspended for every block and an
instruction to continue or end the command sequence is waited for.
Whether the command sequence is suspended or not during the sequence depends on the size
of the block and FIFO. The command sequence ends without suspending the data transfer
when block size ≤ FIFO size. When block size > FIFO size, the command sequence is
suspended by FIFO full. Once the command sequence is suspended, data in FIFO is processed
before the command sequence is continued. In multiblock transfer, the command sequence is
suspended for every block.
In multiblock transfer, when a block size is set to 4 or 8 bytes and the CMDOFF bit of OPCR
is set to 1 for only one block, the command response may not be received correctly. Therefore,
when a block size is set to 4 or 8 bytes, the command sequence must be completed after
reading at least two blocks.
Figures 26.8 to 26.11 show examples of the command sequence for commands with read data.
Figures 26.12 to 26.14 show the operational flows for commands with read data.
• Make settings to issue the command, and clear FIFO.
• Set the START bit in CMDSTRT to 1 to start command transmission. MCCMD must be
kept driven until the end bit output is completed.
Command transmission completion can be confirmed by the command transmit end
interrupt (CMDI).
• The command response is received from the card.
If the card does not return the command response, the command response is detected by
the command timeout error (CTERI).
• Read data is received from the card.
• The inter-block suspension in multiblock transfer and suspension by the FIFO full are
detected by the data transfer end interrupt (DTI) and FIFO full interrupt (FFI), respectively.
To continue the command sequence, the RD_CONTI bit in OPCR should be set to 1. To
end the command sequence, the CMDOFF bit in OPCR should be set to 1, and the CMD12
should be issued.
• The end of the command sequence is detected by poling the BUSY flag in CSTR or by the
data transfer end interrupt (DTI).
Rev. 1.0, 02/03, page 948 of 1294