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C6748 boot pin pull resistors

ReinierC
Expert 2425 points

Hi,

We have developed our own custom board, based upon the C6748. Currently we are experiencing some issues with booting from NOR flash: our system would only boot after a warm reset after an initial power-up. I have noticed that some of our boot pins are connected directly to ground, without a pull-down resistor. These particular boot pins are not used for anything else, except for boot selection.

Can the hardware experts please explain to me what the implications are if pull-resistors are not used for the C6748 boot pins?

Regards

  Reinier

  • 0
    TI__Guru* 84110 points

    Reinier,

    Our recommendation has always been the use of resistors for these boot pins, but if the pins are not used for anything else and you never configure them as outputs, then there should be no problems.

    Do you read the correct values in the boot configuration registers after a reset?

    Regards,
    RandyP

  • 0 in reply to RandyP
    Expert 2425 points

    Hi Randy,

    Thank you for coming back to me.

    I have not read the actual values of the boot registers, but I guess the only way to achieve that, is to connect an emulator to the board after initial power-up? There are also a few other suspects, such as the power sequencing of the board or the flash not being ready when the DSP attempts to boot. We still have to investigate those possibilities, but at least it narrows it down a little bit.

    Regards

      Reinier