Is it possible to use softDevice on nRF52840 without 32k crystal?

[Artak]

Is it possible to use softDevice on nRF52840 without 32k crystal?

[Jørgen Holmefjord]

Hi,

Yes, you can use 32.768 kHz RC oscillator (LFRC) as the clock source.

Best regards,

Jørgen

[Artak]

Hi Jørgen,

I have tried to perform the following changes into ble_app_blinky example:

1. Changed the value of macro CLOCK_CONFIG_LF_SRC to 0 from sdf_config.h
2. Added call to nrf_drv_clock_init() at the very first line of main() function.

But the example still works properly on PDK board only if the 32K xtal is connected.

Do I miss something important?

[Jørgen Holmefjord]

Which SDK version are you using? Note that the clock source used by the softdevice is not the one you configure in the CLOCK peripheral settings in sdk_config.h. In SDK 14.x.0, you can configure clock source for the softdevice using the sdk_config.h macros NRF_SDH_CLOCK_LF_SRC, NRF_SDH_CLOCK_LF_RC_CTIV, and NRF_SDH_CLOCK_LF_RC_TEMP_CTIV.

[Artak]

I'm using the 14.1 version and I was able to make it working after changing the value of NRF_SDH_CLOCK_LF_SRC. Thanks :)