UART unresponsive on custom board

[pdpro]

I have designed a custom board using nRF52832. As per my understanding, we can configure any GPIO pin for UART communication. However, I am not able to configure the board for this communication.

I tried declaration of tx,rx,RTS,CTS using almost all spare pins, but there is no sign of UART communication successfully established. I tried to debug step by step and can see UART pins getting initialized and corresponding registers being assigned.

I am using nRF52840 for programming and debugging my target custom board through SWD. As a first step, I tried loop test on DK (shorting GPIO pin 6 & 8) and it is working fine, however my custom board doesn't have any exposed GPIO pin so I cannot do loop test. Please help me with UART on my custom board. Is there any special hardware connection arrangement needed for this communication?

[pdpro]

As per kenneth reply on my question, I tried one GPIO pin with 2.2KOhm pull-up resistor which I tried to use for RXD. Still there is no sign of communication being established properly.