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 }

[juge90]

How to detect abnormal external low-frequency crystals, then automatically switch to the internal low-frequency crystals？

[bjorn-spockeli]

Why do you need to detect "abnormal external low-frequency crystals" ? I assume that you know which crystal that is on your pcb?

[bjorn-spockeli]

You can the trigger the TASKS_LFCLKSTART task and wait for the EVENTS_LFCLKSTARTED and/or read the LFCLKSTAT register. See this page in the NRF52832 PS.

[juge90]

Before 52832 program into the main function, initialize the clock: Under normal circumstances: NRF_CLOCK - > LFCLKSTAT = 0; After the abnormal: NRF_CLOCK - > LFCLKSTAT = 0 x00010000, (1 low frequency clock is still running, 00 said RC internal clock)

Now, initialize the clock before I join lfclk_stop (), the program will stuck waiting for the clock stopped while (nrf_clock_lf_is_running ())

    // Low frequency clock source to be used by the SoftDevice
#define NRF_CLOCK_LFCLKSRC      {.source        = NRF_CLOCK_LF_SRC_XTAL,            \
                                 .rc_ctiv       = 0,                                \
                                 .rc_temp_ctiv  = 0,                                \
                                 .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM}

[bjorn-spockeli]

After initialization, you mean that after you've called sd_softdevice_enable with the following clock config

    // Low frequency clock source to be used by the SoftDevice
#define NRF_CLOCK_LFCLKSRC      {.source        = NRF_CLOCK_LF_SRC_XTAL,            \
                                 .rc_ctiv       = 0,                                \
                                 .rc_temp_ctiv  = 0,                                \
                                 .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM}

then you read 0x00010000 from the LFCLKSTAT register?