nRF5340 P0.03 not working as UART Rx

[Mick T]

We just switched module provider and used P0.03 as an input for the UART Rx. We tried everything and it didn't work, and switching to a standard I/O it didn't register the voltage in the line. We patched the signal to another I/O and the UART Rx worked fine. Is there a known limitation on P0.03?

There's a change it could be the module provider, but they are typically every good with documenting known issues.

[Einar Thorsrud]

Hi,

P0.02 and P0.03 are NFC pins by default. To use them as normal GPIO's you need to disable the NFC feature in UICR.NFCPINS. The simplest way to do this is to add this line to your prj.conf:

CONFIG_NFCT_PINS_AS_GPIOS=y