I check the function spec that we can use use 32kHz RC as LFCLK, so I have no external 32k crystal connected with XL1/XL2 on my board.
I have set
NRF_CLOCK->LFCLKSRC = (CLOCK_LFCLKSRC_SRC_RC << CLOCK_LFCLKSRC_SRC_Pos);
And
SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_RC_250_PPM_TEMP_8000MS_CALIBRATION, false);
I found that if I start a repeated timer that the interval is APP_TIMER_TICKS(x, APP_TIMER_PRESCALER) (Here x is less than 50), my system will power off soon. Can you let me know what is wrong I did? Thanks Frank