nRF54L15 - Button on P0.03

RE: nRF54L15 - Button on P0.03

Edvin — Fri, 06 Jun 2025 20:34:02 GMT

Hello,

I am glad to hear that you got it working!

I'll close this ticket, but you can re-open it by replying here if you have any issues related to this one.

Best regards,

Edvin

RE: nRF54L15 - Button on P0.03

Patrick — Fri, 06 Jun 2025 00:50:08 GMT

After trying your recommendations, I decided to assemble a second board and now have an operational button. Thank you for the assistance Edvin.

RE: nRF54L15 - Button on P0.03

Edvin — Thu, 05 Jun 2025 20:30:23 GMT

Yes. You are fine to use the GRTC. In fact, this is the low frequency clock for the nRF54L15, so you will need it. But there is a possibility to clock out the GRTC directly, and this can't be done on any pins:

Source: https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/chapters/pin.html

Best regards,

Edvin

RE: nRF54L15 - Button on P0.03

Patrick — Thu, 05 Jun 2025 13:43:41 GMT

Hi Edvin,

You are correct, I do have a custom board and that is what I am currently developing for. I have disabled all of the uart peripherals in my board’s device tree but do have logging and RTT enabled. I am fairly certain I have set CONFIG_SERIAL=n but will confirm I didn’t miss then when configuring the button sample.

It is good to hear that I shouldn’t not need to worry about GRTC. I do not have any pins defined in pinctrl but did include the GRTC node as defined devkit’s board support files: https://github.com/zephyrproject-rtos/zephyr/blob/d8b37753061a9e0ace95204eccddee1f4b4c477b/boards/nordic/nrf54l15dk/nrf54l_05_10_15_cpuapp_common.dtsi#L48

RE: nRF54L15 - Button on P0.03

Edvin — Thu, 05 Jun 2025 13:20:19 GMT

Hello,

[quote user=""]using GPIO P0.03 as a button input in my design[/quote]

So you have a custom board, but I guess you are still building for the nRF54L15 DK?

If you look on the backside of the nRF54L15 DK, you will see some pins and their default use. The P0.03 is by default used for CTS0, which is one of the flow control pins for the UART used for logging. This means that if you build your application with logging over UART enabled (which it is by default), then this pin will be used by the UART.

Try to disable logging, or at least serial logging by adding:

CONFIG_LOG=n (you may set this to y if you use RTT logging)

CONFIG_SERIAL=n

And see if that helps.

CTS is an input pin, which means that if you have started a debug session, the debugger may pull that pin low or high (don't remember whether it is default high or low). In that case, make sure to power cycle your DK, and don't start a UART terminal after it is powered back on, so that the debugger doesn't try to control the P0.03.

Don't worry about the GRTC things. That is not enabled by default, so as long as you don't use it for UART, it should act as a normal GPIO.

Best regards,

Edvin