Custom NRF52840 Board Softdevice Clock Configuration

[David]

Hello, 

I am having problems with a custom NRF52840 Board. My program hands at the ble_stack_init function.

I have encoutered this problem in the past so I have tried the different solutions that worked previously. My board uses both a HF and LF.

    NRF_CLOCK->TASKS_HFCLKSTART = 1;
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

    NRF_CLOCK->TASKS_LFCLKSTART = 1;
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

I have inserted this functions at the beginning of my main function, and I am able to pass these 2 tests. This should mean that both the HF and LF were successfully initialized.

But my program hangs at ble_stack_init when I set NRF_SDH_CLOCK_LF_SRC to NRF_CLOCK_LF_SRC_XTAL. I have also set the correct accuracy (20 ppm)

It works when I set it to NRF_CLOCK_LF_SRC_SYNTH, But I know this is inefficient. 

What could be the problem with the clock setup?

[Turbo J]

Clean your glasses and look closely at the posted source code:

In the second step you start the LF clock with LFCLKSTART but then use the already set HFCLKSTARTED when trying to wait. You wanted to use the LFCLKSTARTED event instead.

[David]

Hello, I changed this to LFCLKSTARTED and I still get the same result. The code passes the test and LFCLK is started. But still hangs at ble_stack_init

[Vidar Berg]

Hello,

You need to select xtal as the clock source in LFCLKSRC before running the LF clock start task. RC is the default clock source after reset.

[David]

Should this be selected in the sdk_config file or it should be called as a function?

My config file already selects this.

#define NRFX_CLOCK_CONFIG_LF_SRC 1

[Vidar Berg]

The sdk_config setting will not be applied when you don't use the clock driver. Try this instead:

NRF_CLOCK->LFCLKSRC = 1; /* Select xtal source */
NRF_CLOCK->TASKS_LFCLKSTART = 1;
while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0);