Information

Enhanced Secure Digital Host Controller
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
Freescale Semiconductor 11-53
For simplicity, the software flow described below incorporates the internal DMA, and the write operation
is a multi-block write with Auto CMD12 enabled. For the other method (CPU polling status) and different
transfer nature, the internal DMA part of the procedure should be removed and alternative steps inserted.
1. Check the card status and wait until the card is ready for data.
2. Set the card block length.
— MMC/SD cards — use SET_BLOCKLEN (CMD16)
— SDIO cards or the I/O portion of SD Combo cards — IO_RW_DIRECT (CMD52) to set I/O
block size bit field in the CCCR register (for function 0) or FBR (for functions 1–7)
3. Set eSDHC BLKATTR[BLKSIZE] to the same as the block length set in the card in step 2.
4. Set eSDHC BLKATTR[BLKCNT] with the number of blocks to send.
5. Disable the buffer write ready interrupt, configure the DMA setting, and enable the eSDHC DMA
when sending the command with data transfer. Set XFERTYP[AC12EN].
6. Wait for the transfer complete interrupt.
7. Check the status bit to see if a read CRC error or any other errors occurred between sending Auto
CMD12 and receiving the response.
11.6.3.1.2 Write with Pause
The write operation can be paused during the transfer. Instead of stopping the SD_CLK at any time to
pause all the operations which is also inaccessible to the host driver, the driver can set
PROCTL[SABGREQ] to pause the transfer between the data blocks. Since there is no timeout condition
in a write operation during the data blocks, a write operation to the cards can be paused in this way and if
line SD_DAT0 is not required to de-assert to release busy state, no suspend command is needed.
Similar to the flow described in Section 11.6.3.1.1, “Normal Write,” the write with pause is shown with
the same type of write operations:
1. Check the card status and wait until card is ready for data.
2. Set the card block length.
— MMC/SD cards — use SET_BLOCKLEN (CMD16)
— SDIO cards or the I/O portion of SD Combo cards — use IO_RW_DIRECT (CMD52) to set
the I/O block size bit field in CCCR register (for function 0) or FBR (for functions 1–7)
3. Set the eSDHC BLKATTR[BLKSIZE] to the same as the block length set in the card in step 2.
4. Set eSDHC BLKATTR[BLKCNT] with the number of blocks to send.
5. Disable the buffer write ready interrupt, configure the DMA setting, and enable the eSDHC DMA
when sending the command with data transfer. Set XFERTYP[AC12EN].
6. Set PROCTL[SABGREQ].
7. Wait for the transfer complete interrupt.
8. Clear PROCTL[SABGREQ].
9. Check the status bit to see if a write CRC error occurred.
10. Set PROCTL[CREQ] to continue the read operation.
11. Wait for the transfer complete interrupt.