RE: NRF54L15 - issue when MCUBoot/Partition Manager is used on a custom board

Vidar Berg — Mon, 24 Nov 2025 12:47:54 GMT

Thanks for the update. Yes, MCUboot will be built using the default configuration for your build target, which for the NRF54L15 DK is the LFXO. If you want to change this, you can create a folder named sysbuild in your project directory, and then add a new file in that folder named mcuboot.conf with the following line:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

Then perform a clean build to allow the build system to detect that a new configuration file has been added ( a clean build is only needed when adding new files, not when editing existing configuration files).

For more details on how this works I recommend having a look at this course: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-8-sysbuild/

Best regards,

Vidar

RE: NRF54L15 - issue when MCUBoot/Partition Manager is used on a custom board

Alex P — Sun, 23 Nov 2025 23:26:14 GMT

Dear Team,

It seems that as my custom board is using internal RC for LFXO (it doesn't have 32 KHz crystal installed), it seems that issue might be somehow related to MCUBoot not using proper crystal selection settings. Can someone provide a guide on how to configure MCUBOOT to select internal RC for LFXO?

Thanks