SH7763 Datasheet, PDF (1417/2026 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

31.5 Operations when Using DMAC
Section 31 Multimedia Card Interface (MMCIF)
31.5.1 Operation in Read Sequence
To transfer data using the DMAC, set MMCIF (DMACR) after setting the DMAC. Transmit the
read command after setting DMACR.
When using DMA, next block read is resumed automatically when the AUTO bit in DMACR is
set to 1 under the condition that normal read is detected after a block transfer end of a pre-defined
multiblock transfer. Figure 31.19 shows an example of the operational flow for a pre-defined
multiblock read in MMC mode using auto-mode.
• Clear FIFO.
• Set the block number to TBNCR.
• Set DMACR.
• Read command transmission is started.
• Command response and read data are received from card.
• When the card does not return the command response, the command response is detected by
the command timeout error (CTERI).
• The end of the command sequence is detected by poling the BUSY flag in CSTR or through
the pre-defined multiblock transfer end flag (BTI).
• An error in a command sequence (during data reception) is detected through the CRC error
flag or data timeout flag. When these flags are detected, set the CMDOFF bit in OPCR to 1,
issue CMD12, and suspend the command sequence.
• The data remains in FIFO after the read sequence end. Set the SET[2:0] bits in DMACR to 100
to read all data left in FIFO if necessary.
• Confirm the DMAC transfer completion and clear the DMAEN bit in DMACR to 0.
• Set the CMDOFF bit to 1 and clear DMACR to H'00 when a CRC error (CRCERI) or
command timeout error (CTERI) occurs in the command response reception.
• Set the CMDOFF bit to 1, clear DMACR to H'00, and clear FIFO when a CRC error
(CRCERI) or data timeout error (DTERI) occurs in the read data reception.
Note: * In multiblock transfer, when the command sequence is ended (1 is written to the
CMDOFF bit) before command response reception ends (CRPI), the command
response may not be received correctly. Therefore, to receive the command response,
the command sequence must be continued (set the RD_CONTI bit to 1) until the
command response reception ends.
Access from the DMAC to FIFO must be done in bytes or words.
Rev. 1.00 Oct. 01, 2007 Page 1351 of 1956
REJ09B0256-0100