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CC2541 - How to setup USART for single-wire UART

ANTHONY CALCE
Prodigy 10 points

I am using the UART module as a single-wire UART (TX and RX shorted).  The problem I am having is that I need to simulate an open drain on the TX pin since it holds the line high when the slave device is trying to transmit.

On most microcontrollers, I would just disconnect the TX pin from the UART module during reception and that seems to work.  On this chip, I've set the TX pin as a GPIO but I still experience this issue (slave tries to transmit but cannot pull the line to 0 volts)

  • 0
    TI__Expert 6995 points

    Hi Anthony,

    I think you've got the right idea setting the TX pin to GPIO. Have you changed the pin to input? Perhaps you should experiment by disabling the pullup as well. Enabled pullup shouldn't be an issue, but I would suggest it for debugging in case there is a drive strength issue on the other side.

    Peder