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TM4C1294NCPDT: Enable internal pull-up resistor on UART pins

Edward Chang
Intellectual 1630 points
Part Number: TM4C1294NCPDT

Hi,

Is it possible to enable internal pull-ups on UART pins? The UART is used for debug/console port and since uart connector will not always be connected to this port, RX interrupt will keep firing while it receives noise. 

Regards,

Edward

  • 0
    Guru 13040 points
    Edward,
    I believe it is possible to enable pull-ups on UART pins (or more likely, on the Rx pin).
    But that does not seem to be a solution.
    - You should not have all that much electric noise to cross the border of GPIO interrupts just because your port is floating.
    - If by "noise" you mean "garbage transmission received on UART", then all you need to do is disable the UART interrupts when you don't want them anymore.
    Meanwhile, if the pull-up doesn't work with the UART configured (please check), then you could set the pin as GPIO Input, enable the pull-up, and set your software in a way that, when there is a lowering border interrupt, configure the pins as UART - you may loose the first byte, but that shouldn't be a problem for a decent protocol. But again, I don't think there should be that much electric noise, consider some additional protection on your circuit.
    Bruno
  • 0
    TI__Guru**** 244400 points
    Hello Edward,

    Yes it is possible to do so. To enable the Pull up on the pin call the following API with the correct Port and Pin number

    GPIOPadConfigSet(PORT, PIN, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU)