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!

[Michal]

Thank you for the information! Good to hear that.

Depending on what your custom board files were based on, there may have been more setup in the DK's files compared to your custom board.

Best regards,

Michal