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AM6442: AM6442BSEFHAALV - eMMC interface

Nikhilraj KB
Prodigy 180 points

Part Number: AM6442

Tool/software:

Hi all, 

In our custom board we are facing some random issues with eMMC

EMMC hangs on Flashing - We are transferring about 1GB to EMMC , but it hangs randomly , some times on start or in the middle, and in some  times we can complete the action

While booting also hanging issues comes randomly . 

in hardware we are unstuffed the pullup/down resistors for data , clk , strobe etc . Please see the below schematics . We would like to get your feedback on this . in EVK  it observed CLK pull up and STROBE pulll down is mounted .Do we need to follow the same ?( Some articles suggests it can be unmounted as internal pullup is there for processor).

We tried with HS200 and lower rate mode (52)  , all modes have this issue

 .6064.EMMC.pdf

  • 0
    TI__Guru 64655 points

    The external pulls should not impact data transfer. The external pulls are only needed to hold the signals in a valid logic level when not driven. For example, the eMMC specification requires an eMMC device to have internal pulls on its DAT[7:1] pins turned on by default. The eMMC device does not have internal pulls on its CLK, CMD, and DAT0 pins. You need to have external pulls on these signals to prevent these signals from floating until software has initialized the AM64x device. The current recommendation is to include an external pull-down on CLK, and an external pull-up on CMD and DAT0.

    Was your PCB design to be compliant to the PCB delays defined in the MMC0 Timing Conditions table?

    Have you check the signal quality of the eMMC signals on you PCB implementation?

    How many PCB assembly have you tested?

    Have you been able to determine if your issue is the result of write or read operations?

    Regards,
    Paul