RTT Not Showing and Code Stopping on Custom Board (nRF9151)

[gmassana]

Hi everyone,

I am experiencing an issue with my custom board configuration for the nRF9151. When using the same code that works with the nRF9151 DK configuration, I encounter the following:
• GPIO behavior: The GPIO pin is set high, but when I connect with the RTT Viewer, the pin drops to low and no output is shown.
• RTT output: With the DK configuration, I see the “Hello World!” message in the RTT Viewer. However, with my custom board configuration, no RTT output appears.

Setup:
• Debugger: Segger J-Link Mini EDU
• The custom board configuration raises the GPIO initially, but no RTT output is shown when connected.

I have checked the SEGGER RTT settings in prj.conf and GPIO configuration, but I can’t identify the issue. Could this be related to memory partitioning or device tree settings for the custom board?

Thanks!

[Michal]

Hello,

Just a quick check: does the same happens while using Segger J-Link Mini EDU and the on-board debugger?

Are you able to test that?

Best regards,

Michal

[gmassana]

Hello,

I found the solution.

I’m not sure why, but uart0 must be configured in the .dtsi file. After adding the following configuration, everything started working correctly:

&uart0 {
    status = "okay";
    current-speed = <115200>;
    pinctrl-0 = <&uart0_default>;
    pinctrl-1 = <&uart0_sleep>;
    pinctrl-names = "default", "sleep";
};

With that, it worked. Thank you!