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Bootup successed only with the first priority device in boot mode setting.

Eric Chen
Intellectual 810 points

Hi,

   We developed a custom board using DM8148 with NOR flash and SPI flash, and modified u-boot to boot up. According to TRM, there are priorities for the 4 boot device with specific boot mode setting. For example, if I set BTMode[4:0]=0001h, the boot device priority shall be UART, XIP, MMC then SPI.

   I can't boot up by NOR flash (XIP) or SPI flash with such boot mode 0001h. How could ROM boot switch to other low priority device to boot up if the first is not able to boot up? Thanks.

 

Regards,

    Eric

  • 0
    TI__Intellectual 2725 points

    1. Are you able to access NOR and SPI regularly?

    2. Are you following ROM Code specification for Booting from NOR & SPI while flashing the images to them. Verify once again with TMS320DM814x DaVinci Digital Media Processors Technical Reference Manual - Section 1.7.2 for NOR & 1.7.5 FOR SPI.

    Regards

    Gururaja

  • 0 in reply to Gururaja Hebbar
    Intellectual 810 points

    Hi Gururaja,

    1. Yes both NOR and SPI flash could be accessed.

    2. Our NOR flash boot code is under debugging and not able to boot up yet, but boot code for spi flash is okay. And caould be flashed by modified flash writer. If I set the boot mode as 10110h that spi is the first boot device, board could be boot up by spi flash.

     

    Regards,

        Eric

  • 0 in reply to Eric Chen
    TI__Expert 6175 points

    Eric,

    The most likely problem is that you are not disconnecting the SYSBOOT pin pull up after reset is released. As the GMPC DATA lines and the SYSBOOT are muxed on the same pins, the pulls that are put on the SYSBOOT line will cause the DM8148 to read the value of the SYSBOOT as valid data from the NOR.

    The ROM expects the first four words of the NOR to be either 0x0000 or 0xFFFF if it is empty or contains no valid image. In your case, most likely the ROM reads NOR data as the with the SYSBOOT pull ups enabled and would try to boot from it. Of course that would result in the A8 executing garbage and the execution will die.

    You will need to add external circuitry to disconnect the SYSBOOT pulls when reset is released.

    Regards,

    Madan

  • 0 in reply to Madans
    Intellectual 810 points

    Hi Madan,

        When I set bootmode as 10000 which the boot device priority is NOR-->UART-->EMAC-->MMC, and erased NOR flash. I can't boot from UART. So boot up looks work by device priority. Thank for your help.

        For NOR flash boot up problem, I think it's another issue irrelative to boot device priority.

    Regards,

        Eric