How to use ble_uart example using 16Mhz. without 32khz

[cirid]

i think ble_uart example based on 32Khz. but my board do not have 32khz osc.(by miss design)

how to running ble_uart example using only 16Mhz?

[Hieu]

In ble_stack_init(), there is a call to SOFTDEVICE_HANDLER_INIT(). Try changing the clock source parameter like this: SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_RC_250_PPM_4000MS_CALIBRATION, NULL); If I understand things correctly, that should, via SoftDevice API, change LFCLK source from external 32.768kHz to internal RC oscillator. Doing this fixed our issues with a bad 32.768kHz on our nRF51 DK.

I try digging around to see where LFCLK matters for other peripherals but I could not find anything... The reference manual only have a diagram saying the Clock block provide clock for all peripheral via APB bus, that's it.

Interesting, I never noticed this until trying to answer your question, but I have never had to worry about configuring clk for peripherals.. It seems the system automatically takes care of that somehow. Perhaps someone more experienced could explain more in depth.

[Sigurd]

The SoftDevice uses one of two available low frequency clock sources(32 kHz): the internal RC Oscillator, or external Crystal Oscillator.

If you don’t have an external 32 kHz crystal, you must use the internal RC Oscillator.

[Sigurd]

Are you using a nRF51 or a nRF52?

[cirid]

thank you for your answer. i see that softdevice_handler_init() in ble_stack_init(). replaced NRF_LFCLKSRC_RC_250_4000ms_CALIBRATION(also start HFCLK, TASKs_CAL, and check 16mHZ output at osc), but didn'y working. my circuit is reference on QFAA QFN48 schematic with low voltage mode setup(exactly same without 32khz)

[cirid]

using nrf51822