How to detect the external low-frequency vibration crystal work?When it doesn't work how to switch frequency crystals?

[juge90]

52832，SDK12.0.0

I met such a situation: In the use of JLink burning program or air upgrade, after the completion of the program card died in initialization low-frequency crystals.

"sd_softdevice_enable(p_clock_lf_cfg, softdevice_fault_handler);"

[bjorn-spockeli]

You need to modify the NRF_CLOCK_LFCLKSRC in the pca10040.h or custom_board.h to the following

#define NRF_CLOCK_LFCLKSRC      {.source        = NRF_CLOCK_LF_SRC_RC,            \

                                 .rc_ctiv       = 16,                             \

                                 .rc_temp_ctiv  = 2,                              \

                                 .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_250_PPM }

[bjorn-spockeli]

Have you confirmed that you have the correct load caps for the external crystal? I have never seen this issue before, i.e. that the XTAL does not start up correctly when you set NRF_CLOCK_LF_SRC_XTAL as source, provided that a crystal with the correct specs and the correct load caps are used.