SH7720 Datasheet, PDF (1150/1524 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series

Section 31 MultiMediaCard Interface (MMCIF)
31.5 Operations Using DMAC
31.5.1 Operation of Read Sequence
For transfer with DMAC, set MMCIF (DMACR) after setting DMAC. Transmit the read
command after setting the DMACR.
Figures 31.23 to 31.26 show the operational flowcharts for read sequence.
• FIFO is cleared and DMACR is set.
• Read command transmission is started.
• Read data is received from the MMC.
• After read sequence, FIFO includes data. If necessary, 100 is written to the SET2 to SET0 bits
in DMACR to read every data in FIFO.
• The end of the transfer with the DMAC is confirmed, and 0 is set to the DMAEN bit in
DMACR.
• When the CRC error (CRCERI) or the command timeout error (CTERI) occurs during
command response reception, write 1 to the CMDOFF bit and set DMACR to H'00.
• When the CRC error (CRCERI) or the data timeout error (DTERI) occurs during read data
reception, write 1 to the CMDOFF bit and set DMACR to H'00 to clear the FIFO.
When the DMA is in use, and detected that reading is completed successfully after block transfer
in pre-defined multiblock transfer, reading the next block is automatically performed again by
setting the AUTO bit in DMACR to 1. Figures 31.27 shows the operational flowchart for pre-
defined multi read sequences in MMC mode.
• FIFO is cleared.
• The number of blocks is set to TBNCR.
• DMACR is set.
• Read command transmission is started.
• Command response and read data are received from the MMC.
• If the MMC does not return the command response, it detected by the command timeout error
flag (CTERI).
• Command sequence end is detected by polling the BUSY flag in CSTR or the multiblock
transfer (pre-defined) end flag (BTI).
• Errors during command sequence (data reception) are detected by the CRC error flag and the
data timeout error flag. When these flags are detected, set the CMDOFF bit in OPCR to 1 to
issue the CMD12 command and suspend the command sequence.
Rev. 3.00 Jan. 18, 2008 Page 1088 of 1458
REJ09B0033-0300