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

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

Thomas Y — Sun, 25 Mar 2018 05:29:05 GMT

How about using RX pin as GPIO output pin ?

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

PaukSK — Thu, 20 Apr 2017 16:41:56 GMT

I was just curious, if it was possible. I couldn't get it to work.

Already connected it externally. Thanks :)!

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

Stian Røed Hafskjold — Thu, 20 Apr 2017 15:23:25 GMT

No this is not possible. You could maybe disable the peripheral, reconfigure the PSELR(T)XD registers and GPIOs before re-enabling again. But why not just connect the two pins externally.

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

PaukSK — Mon, 10 Apr 2017 00:36:45 GMT

Oh, I see now about the different peripherals. Thanks.

I know exactly, when I want to receive and when to transmit. So I change the pin state accordingly. And disable recieve when transmitting and vice versa.

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

RK — Sun, 09 Apr 2017 23:53:43 GMT

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.

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

PaukSK — Sun, 09 Apr 2017 23:39:24 GMT

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.