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AM5728: Boot from NAND the sysboot PIN conflict with GPMC_ADx.

Part Number: AM5728

Hi all,

When am57xx boot from nand the sysboot PINs conflict with GPMC_ADx, how to workaround this? thanks!

BR,
Denny

  • Denny,

    Can you please confirm the hardware and software combination in which this issue is being seen?

    Regards

    Karthik

  • Thanks for your reply!

    The schematic diagram is attached.

    I want to boot  from NAND flash device, but the ad pin of NAND flash (GPMC interface) is multiplexed with sysboot pin.  Sysboot pin is pulled down to 1V(as shown in the figure) when AM5728 during startup, and sysboot cannot identify which device to boot from. Is it necessary to add isolation chip between am5278 and NAND?Or the resistance between them (75 Ω) is too large?Thank you!

  • The ADx pins are floating during reset - neither the processor or flash memory device are driving.  Therefore using pullup or pulldown resistors - you can set the SYSMODE value.  From you schematic snip-it - it appears you have both pull-up and pull-down resistor(s) installed.  This is set the voltage in the middle - 1.5V.  You should install either pull-up or pull-down resistor based on what SYSMODE value you wish - but never install both pull-up and pull-down on same net.