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TMS320F28377S: Input GPIO state change

Rohit Subramanian30
Prodigy 100 points
Part Number: TMS320F28377S


I am not seeing an GPIO intput pin change state in the microcontroller even though I can probe it and confirm the state change on the board. This problem only happens when I setup the pin to have an input pull up. I have a 10K pull up on my circuit externally. When i set the PUD to disable pull up internally I can detect the state change. Why is this the case?

Thanks,

Rohit.

  • 0
    TI__Genius 15260 points

    Hi Rohit,

    I suspect that the internal pull may be pulling the pin above ground internally. Are you able to try a stronger pull-down resistor? The internal pull-up is very weak so this is not typically an issue.

    Regards,

    Kris

  • 0 in reply to Kris Parrent
    Prodigy 100 points

    Kris,

    Thanks a lot for responding.

    I have an external 10 K pull up and had set this GPIO pull up enable. This would mean that it is being strongly pulled up to V. When I toggle the state of this pin to ground, I see the change on the oscilloscope, but not inside the MCU. However, when I set the GPIO pull up to disable, I read the state change internally. As for the toggle circuit, I am just using a switch with one pin connected to V and the MCU and the other pin directly connected to ground. So not sure I understand your point.

    Thanks,

    Rohit.