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TMS320C6748: 4 bit ECC NAND flash going away

Blair MacDonald
Intellectual 610 points

Part Number: TMS320C6748

Various suppliers have told us that 4 bit ECC NAND flash is going to go away. All seem to be coming out with 8 bit and higher that handles the ECC calculation on board the flash. What are the implications of this to the bootloader on the C6748 going forward?

Thanks,

Blair

  • 0
    TI__Guru**** 161600 points
    Hi Blair,

    I've forwarded this to the design team.

    They will post their feedback directly here.

    Best Regards,
    Yordan
  • 0
    TI__Guru** 116950 points
    Unfortunately, this is not just a bootloader level question but a device level question. The device is built in with EMIFA IP which can support only upto 4 bit ECC during read/write access to NAND flash memory using HW.

    From boot perspective, we will not be able to support NAND devices that have higher ECC requirement so we would recommend using other boot modes like SD/MMC, parallel NOR or SPI flash.
  • 0 in reply to Rahul Prabhu
    Intellectual 610 points

    But couldn't the bootloader simply support a mode with no ECC and allow the flash chip to handle it in the case where the flash has ECC built in?

    Blair

  • 0 in reply to Blair MacDonald
    TI__Guru** 116950 points

    ROM bootloader is software that is pre-programmed in the silicon and can`t be changed. The design of NAND bootloader by default always uses ECC data with NAND because there are bit flips on the NAND flash devices over its life cycle and the ROM bootloader is designed to boot the device reliably over the lifetime of the part in the field. There is no option to bypass the ECC mechanism in the bootloader.

    This is a device that was designed 8-10 years back and we didn`t have this usecase when the ROM bootloader was designed. Some of our more recent devices like AM437x has mechanism to inform the bootROM not to use ECC mechanism using boot switches and to let the NAND to handle this.

    Regards,
    Rahul