Example of using internal oscillator with BLE?

[Jeffrey Haynes]

Can someone please post a simple example of using the internal oscillator with BLE?  Modifying the ble_app_blinky example to use the RC would be ideal.  No matter what I do I can't get it to work (depending on what I try I get different internal errors) and simply changing the sdk_config does not seem to work.

[RK]

which internal oscillator, the 32kHz or the 16/64MHz (you don't say what chip you're using). What 'internal errors', we can't guess. 

[Jeffrey Haynes]

I wonder why the forum forces you to select the part if it isn’t going to show up here...

NRF52840. Various errors. I’m looking for an example of how to do this correctly, not feedback on what I’ve tried. Thanks. 

[Sigurd]

Hi Jeff,

In sdk_config.h, make sure that you have the following:

// </h> 
//==========================================================

// <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
#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
#endif

// <o> NRF_SDH_CLOCK_LF_XTAL_ACCURACY  - External crystal clock accuracy used in the LL to compute timing windows.
 
// <0=> NRF_CLOCK_LF_XTAL_ACCURACY_250_PPM 
// <1=> NRF_CLOCK_LF_XTAL_ACCURACY_500_PPM 
// <2=> NRF_CLOCK_LF_XTAL_ACCURACY_150_PPM 
// <3=> NRF_CLOCK_LF_XTAL_ACCURACY_100_PPM 
// <4=> NRF_CLOCK_LF_XTAL_ACCURACY_75_PPM 
// <5=> NRF_CLOCK_LF_XTAL_ACCURACY_50_PPM 
// <6=> NRF_CLOCK_LF_XTAL_ACCURACY_30_PPM 
// <7=> NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM 

#ifndef NRF_SDH_CLOCK_LF_XTAL_ACCURACY
#define NRF_SDH_CLOCK_LF_XTAL_ACCURACY 1
#endif

[Jeffrey Haynes]

Thanks, I’ll give it a try!

[Jeffrey Haynes]

Just an update on this. We’ve tried using these settings with our custom board with no luck. The BLE stack, gatt, connection, advertising, etc. all happily initialize but there’s no energy at all on the antenna and no signal. 

Maybe you can clarify something to assist in debugging. The LF clock definitions appear to exist in two places; in the sdk_config and in pca10056 as NRF_CLOCK_LFCLKSRC. Which is the correct one?  Is the board definition a holdover from an older sdk?  In short, how can I be confident that the dk board is actually using the internal oscillator?

Thanks

[Jeffrey Haynes]

Success!  We were missing the external wire connecting DEC4 to DEC6 that changed in the silicon rev.

[Rob Philip]

Jeff:

Two years after this "success" posting from you I was searching to try and find out what I was configuring incorrectly on my nRF52840 using the RC clock. I saw your comment on DEC4 to DEC6 and took a look. In fact my hardware guys had *not* connected DEC4 & DEC6. A small flywire and magically my BLE radio began working. Thanks so much for coming back and making that final note on your problem.