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DM3730 EMMC read/write slow

Yi Yang3
Prodigy 90 points
Other Parts Discussed in Thread: CSD

Hi everyone,

I am trying to connect  to my EMMC device at MMC3 on the board. The following is what I got:

  • I have finished all the init steps with no error and the card can read and write correctly.
  • The EMMC card support JEDEC 4.4.1. 
  • The block size is set to 512 bytes
  • The clock is set to 48MHz(Observed from scope)
  • The card has been set to high speed mode and 8 bit data width (Observed from EXT_CSD register by calling CMD8)
  • The processor has been set to 8 bit mode. 
  • For writing one block (512B), it takes about 1500 microseconds.
  • For reading one block, it takes about 500 microseconds.
  • The first time of the writing task will take 13000 microseconds and for the reading task.
  • I can observe the card response the data crc status really fast after all the 512B transferred with scope.

I have worked on it for a few days but I couldn't make any progress. Please let me know if you have any idea for this issue. Thanks a lot.