NRF5340: How to configure P0.02 and P0.03 (NFCT) as GPIO?

[bubune]

Hello,

We are working with the nRF5340DK using nRF Connect SDK v2.9.1.
Our firmware targets the nrf5340dk_nrf5340_cpuapp_ns board.

We would like to use P0.02 and P0.03 as GPIOs, specifically as UART2 RX and TX.
From what I have read (for example, here: nRF5340: best way to configure P0.02 (NFCT) as GPIO with TFM ), it seems that no special configuration is required—these pins should be usable as UART pins by simply configuring them in the device tree.

However, while I can successfully configure and use other pins as UART, when I assign P0.02 and P0.03, I am not able to send or receive any data.

Is there any additional configuration required to use these two pins as UART?

Regards,
Bruno

[Turbo J]

bubune said:

these pins should be usable as UART pins by simply configuring them in the device tree.

The backside printing on my NRF5340DK implies otherwise - it shows a not connected (NC) component between the pin header and the GPIO on the NRF chip. Its only connected to the NRF antenna inputs.

No idea if that changed between board revisions, this board here is the version before they changed the debugger chip to an NRF variant.

[bubune]

Thanks, I was looking at the 2.0.0 schematic revision of the DK board, but I actually have a 2.0.2 DK board. On the 2.0.2 version, the GPIOs are not connected by default — resistors need to be added and NFC's  resistor removed.