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AM4377: AM4377 pin asign for eMMC Memory

Part Number: AM4377

Hi Biser,

for eMMC connection i use TI Pin Mux Tool and saw how to assigned all pins. But for MMC1_RSTn signal who pin is suitable. Thanks for your help.

Best Regards,

Taner.

  • My recommendation is:

    1. The nRESETIN_OUT signal is an open drain signal (i.e. requires a pullup).  Put a buffer on this pin such that you get a push-pull version of this same signal.
    2. Connect the push-pull output of the buffer to the eMMC reset signal and any other devices that are required to be in a good state after the CPU is reset.

    Assuming you're booting from the eMMC, you need to make sure the eMMC is in a good state any time the CPU is reset.  The nRESETIN_OUT signal drives low in response to all reset sources (e.g. porz, software reset, watchdog, etc.).  This ensures that the eMMC gets reset any time the CPU is reset.

    If you want the ability to optionally force a reset using a GPIO, you can add another AND gate between the buffer and the reset.  The two inputs to the AND gate would be your original push-pull reset signal as well as a GPIO of your choice.  You should either choose a GPIO that defaults to being pulled high (e.g. gpio1_28) or else you a sufficiently strong external pullup to overcome the internal weak pullup.

    One last note...  I want to make sure you understand that the eMMC RST signal doesn't actually do anything by default.  In other words, there's a one-time programmable bit inside the eMMC that you must first write in order for the reset signal to function.