Configure external clock 32.768K

RE: Configure external clock 32.768K

Simonr — Thu, 13 Jun 2019 10:24:38 GMT

NRF_CLOCK_LF_SRC_XTAL is the external LF clock.

Best regards,

Simon

RE: Configure external clock 32.768K

Josh_1 — Thu, 13 Jun 2019 09:47:10 GMT

maybe I miss something, How to configure the SoftDevice ,which type I need to choose?

// <0=> NRF_CLOCK_LF_SRC_RC

// <1=> NRF_CLOCK_LF_SRC_XTAL

// <2=> NRF_CLOCK_LF_SRC_SYNTH

RE: Configure external clock 32.768K

awneil — Thu, 13 Jun 2019 08:51:30 GMT

How to properly post source code:

RE: Configure external clock 32.768K

Simonr — Thu, 13 Jun 2019 08:50:53 GMT

Hi Josh

How to set LFXO to rail to rail was described in the link provided in my last reply.

Best regards,

Simon

RE: Configure external clock 32.768K

Josh_1 — Thu, 13 Jun 2019 07:54:46 GMT

Hi,

I need to configure the SDK SoftDevice clock configuration to work with external Oscillator (square wave).

At the SDK below you can see just three "NRF_CLOCK" options to choose from and there is not LFXO rail to rail like you suggest.

Please advise.

Thanks

// <h> Clock - SoftDevice clock configuration

//==========================================================

// <o> NRF_SDH_CLOCK_LF_SRC - SoftDevice clock source.

// <0=> NRF_CLOCK_LF_SRC_RC

// <1=> NRF_CLOCK_LF_SRC_XTAL

// <2=> NRF_CLOCK_LF_SRC_SYNTH

#ifndef NRF_SDH_CLOCK_LF_SRC

#define NRF_SDH_CLOCK_LF_SRC 0

#endif

// <o> NRF_SDH_CLOCK_LF_RC_CTIV - SoftDevice calibration timer interval.

#ifndef NRF_SDH_CLOCK_LF_RC_CTIV

#define NRF_SDH_CLOCK_LF_RC_CTIV 16 //0

#endif

// <o> NRF_SDH_CLOCK_LF_RC_TEMP_CTIV - SoftDevice calibration timer interval under constant temperature.

// <i> How often (in number of calibration intervals) the RC oscillator shall be calibrated

// <i> if the temperature has not changed.

#ifndef NRF_SDH_CLOCK_LF_RC_TEMP_CTIV

#define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 2 //0

#endif

// <o> NRF_SDH_CLOCK_LF_ACCURACY - External clock accuracy used in the LL to compute timing.

// <0=> NRF_CLOCK_LF_ACCURACY_250_PPM

// <1=> NRF_CLOCK_LF_ACCURACY_500_PPM

// <2=> NRF_CLOCK_LF_ACCURACY_150_PPM

// <3=> NRF_CLOCK_LF_ACCURACY_100_PPM

// <4=> NRF_CLOCK_LF_ACCURACY_75_PPM

// <5=> NRF_CLOCK_LF_ACCURACY_50_PPM

// <6=> NRF_CLOCK_LF_ACCURACY_30_PPM

// <7=> NRF_CLOCK_LF_ACCURACY_20_PPM

// <8=> NRF_CLOCK_LF_ACCURACY_10_PPM

// <9=> NRF_CLOCK_LF_ACCURACY_5_PPM

// <10=> NRF_CLOCK_LF_ACCURACY_2_PPM

// <11=> NRF_CLOCK_LF_ACCURACY_1_PPM

#ifndef NRF_SDH_CLOCK_LF_ACCURACY

#define NRF_SDH_CLOCK_LF_ACCURACY 1 //7

#endif

RE: Configure external clock 32.768K

Simonr — Wed, 12 Jun 2019 11:53:50 GMT

Hi Josh

Yes, you can. It's important that the clock applies a rail-to-rail clock signal. Please read more on how to configure the 32.768 kHz oscillator here.

Best regards,

Simon

RE: Configure external clock 32.768K

Josh_1 — Wed, 12 Jun 2019 06:55:48 GMT

Hi,

I`m using nRF52832.

Can I use external 32.768K square wave Oscillator?

If yes what is the hardware and software configuration?

Thanks

RE: Configure external clock 32.768K

Simonr — Fri, 07 Jun 2019 09:02:24 GMT

Hi Josh

As awneil says, please see the sdk_config.h file and particularly the NRFX_CLOCK_CONFIG_LF_SRC define.

For configuration of the clock versus crystal, please refer to this table.

Best regards,

Simon

RE: Configure external clock 32.768K

awneil — Fri, 07 Jun 2019 07:48:38 GMT

You haven't said what chip you're using.

Have you checked what the Product Specification for your chip says?

Take a look at the Rigado blog post linked here:

https://devzone.nordicsemi.com/f/nordic-q-a/46564/error-133-0x85-gatt-error-on-nrf52840/185362#185362

Although it is about using the internal RC, it does give some explanation of what all the settings are.

Also, look at the comments in the sdk_config.h file - they also give brief descriptions of the settings.

For viewing & editing the sdk_config.h file, see:

https://devzone.nordicsemi.com/f/nordic-q-a/45362/cmsis-configuration-wizard---option-highlighting/178343#178343

RE: Configure external clock 32.768K

Josh_1 — Fri, 07 Jun 2019 06:02:26 GMT

Additional issue is what is the configuration for using Clock instead of crystal, e.g connecting LF (32.768) external clock to XL1 and XL2 to GND.

Thanks