Is it physically possible to set UART RX and TX to same GPIO pin?

[PaukSK]

I'm trying to implement send && recieve through one wire. Handling of pin state, if it is input or output is done via SW. Also it is going to be half-duplex only.

Is it possible to do something like this:

NRF_UART0->PSELTXD=PIN_TX_RX;
NRF_UART0->PSELRXD=PIN_TX_RX;

After some experimentation I was unable to get it to run.

[PaukSK]

Found answer in nRF51_RM_v3.0

"Only one peripheral can be assigned to drive a particular GPIO pin at a time. Failing to do so may result in unpredictable behavior."

They will need to be connected appropriately externally.

[RK]

That's not really what that section means, it's saying you can't assign the same GPIO pin to two different peripherals, ie you can't set the same pin in UART0 and SPI0 or similar. It doesn't say that the same pin cannot be used twice in a single peripheral. However given the different setup (input vs output) I would think it's pretty unlikely you can use one pin as TX and RX in the UART as you've found.