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TMS320F28069M: GPIO Pin is Driven High on Power Cycle and Flash

James McKenna
Prodigy 136 points
Part Number: TMS320F28069M


I have an alarm connected to GPIO32 which is active high if the PCBA temperature gets too high. Toggling the GPIO between high and low is no problem. The issue is that when I cycle power to the board the pin is driven high for a moment and the alarm chirps. What is even worse is that flashing the compiled program to the board drives the pin high for the entire duration of the flash. Is there a setting in CCS to prevent this from happening?

  • 0
    TI__Prodigy 290 points

    Hi,

     

    Our expert will get back ASAP.

     

    Thanks,

    Saravanan

  • +1
    TI__Guru* 95315 points

    James,

              All GPIO pins have an internal pull-up (albeit a weak one), which is enabled by default upon power-up (with the exception of the PWM pins). You can add an external pull-down resistor to keep this pin low during power-up. This resistor should be correctly sized so that the device is able to drive the pin high when desired. IOW, don’t size the PD resistor so low that the device is unable to overdrive it. This should also help you in the situation during flash programming. Note that all GPIO pins come up in the input configuration upon reset.