Using P0.26 with App Timer

[phipi]

I have an application that toggles an LED on P0.26 based on a timer and that's working fine. Now I need to add a few more timers so I decided to use the APP_TIMER library with the RTC, but when I make the call to nrf_drv_clock_lfclk_request(), I am no longer able to control P0.26. I see that this pin is connection for the 32kHz crystal but I don't actually have an external reference.

Do I still lose functionality of this pin even without an external crystal?

[RK]

No you do not - so you have a different issue

[phipi]

"Function for requesting LFCLK. LFCLK can be repeatedly requested.

If it is first request, selected LFCLK source will be started. The nrf_drv_clock_lfclk_is_running() function can be polled to check if it has started."

Any thoughts on what "requesting LFCLK" means exactly? Is this equivalent to enabling it?

Also, how do we specify "selected LFCLK source"?

[RK]

You pick the LF clock source when you start the softdevice. If you don't have a softdevice then you start the LF clock source yourself and choose it then, so there isn't a parameter in the timer library and there doesn't need to be, it just uses the LF clock source you already started.

[phipi]

I'm not using the softdevice. I was able to work around by using this:

  NRF_CLOCK->LFCLKSRC = (CLOCK_LFCLKSRC_SRC_RC << CLOCK_LFCLKSRC_SRC_Pos);
  NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
  NRF_CLOCK->TASKS_LFCLKSTART = 1;

  // Wait for the low frequency clock to start
  while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0) {}
  NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;

instead of nrf_drv_clock_lfclk_is_running(). Does that make sense?

[Jørn]

When using the LFCLK driver the clock source is defined in sdk_config.h with the CLOCK_CONFIG_LF_SRC define. This is used as argument in the nrf_clock_lf_src_set function call, line 197 of nrf_drv_clock.c. Have you tried setting the define in sdk_config.h to 0 (RC source)?