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

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

bubune — Tue, 30 Sep 2025 14:06:20 GMT

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.

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

Menon — Tue, 30 Sep 2025 13:08:17 GMT

Hello,

The nrfprog --memrd value you shared confirms that the pins are configured as GPIOs (see this page). So, this might not be the issue you are seeing.

Kind Regards,

Abhijith

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

Turbo J — Tue, 30 Sep 2025 12:36:00 GMT

[quote userid="3376" url="~/f/nordic-q-a/124675/nrf5340-how-to-configure-p0-02-and-p0-03-nfct-as-gpio"]these pins should be usable as UART pins by simply configuring them in the device tree.[/quote]

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.

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

bubune — Tue, 30 Sep 2025 12:08:31 GMT

In addition, when I read the NFCPINS UICR register (0x00FF8028), I get the value 0xFFFFFFFE:

nrfjprog --memrd 0x00FF8028
0x00FF8028: FFFFFFFE

which is the expected value for configuring the pins as GPIO instead of NFC.

I don't knwon what I miss.

Regards,

Bruno

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

bubune — Tue, 30 Sep 2025 11:50:44 GMT

Hello Abhijith,

Thanks for your quick reply.

As explained in the link in my previous post, the symbol uicr is not known in the nrf5340dk_nrf5340_cpuapp_ns target.

I've already tried this solution before, but here is the compile log output:

Found devicetree overlay: /Users/nono/Documents/git/firmware/app.overlay
devicetree error: /Users/Nono/Documents/git/firmware/app.overlay:23 (column 1): parse error: undefined node label 'uicr'
CMake Error at /Users/Nono/Documents/git/firmware/zephyr/cmake/modules/dts.cmake:295 (execute_process):
  execute_process failed command indexes:

    1: "Child return code: 1"

Regards,

Bruno

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

Menon — Tue, 30 Sep 2025 08:48:39 GMT

Hello,

You need to use a devicetree overlay to configure the NFCT pins as GPIOs. Please try the following overlay file:

&uicr {
nfct-pins-as-gpios;
};

See this devzone case as a reference.

Kind Regards,

Abhijith