nrf5340 sysbuild LFCLK loop

Question

Hello, 
 I have a custom nrf5340 board without a 32kHz clock attached. When using a sysbuild configuration (with MCUBOOT) and debugging the code I get stuck in this LFCLK loop: 
 
 I tried using another nrf5340dk and cut the SB1 and SB2 with the same results of the LFCLK loop. I have added the configs to both the prj.conf of the app core and net core: 
 
 CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC =y 
 CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL =n 
 
 to the project but the results are the same. I tried changing the config to K32SRC_SYNTH and K32SRC_PPM and the problems persists. 
 
 I am using: -nrf5340dk_nrf5340 -SDK v2.6.0

ecc · Accepted Answer

I also had the same problem. It turns out that the prj.conf settings are not applied to MCUBoot, and so I had to add 
 CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC =y CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL =n 
 to sysbuild/mcuboot.conf so that MCUBoot would also be told to use the RC oscillator, instead of the XTAL. 
 
 Edit: I actually ended up putting those two lines into my custom board's defconfig file, so that the LFCLK source gets picked up no matter what type of build system is performed.

nrf5340 sysbuild LFCLK loop

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