internal rc slow clock problems with sdk12 and sdk14

RE: internal rc slow clock problems with sdk12 and sdk14

robotjosh — Fri, 02 Feb 2018 15:15:57 GMT

The slow clock does actually work with sdk12 and sdk14. Check the error registers, something might be hard faulting. This problem I reported was actually because it was having a uart rx hard fault if the rx line is disconnected and not pulled high.

RE: internal rc slow clock problems with sdk12 and sdk14

jumpingfool — Fri, 26 Jan 2018 01:18:24 GMT

Sorry to revive this old thread but I am having this same issue with using the RC clock source and the bootloader in SDK 14.2. Symptoms are that the board won't run until given an external kick - all it requires is JLINK to be connected once (not even debugger connected) and then the board runs and can be disconnected from the programmer.

If I flash just the application without the bootloader (so the Softdevice handles clock initialisation) then the board runs fine without the need for the initial JLINK kick.

I have eliminated a clock configuration issue - I've traced through the bootloader initialisation and it is pulling the correct values from sdk_config.h when making the call to nrf_drv_clock_init.

My suspicion is that the clock initialisation code in the SDK 14 bootloader is missing a step necessary to start the RC oscillator. This wouldn't be immediately obvious on the DK board as the debug interface would generally be active and this seems to be enough to kick the RC into life.

This is driving me crazy - any help would be gratefully received!

RE: internal rc slow clock problems with sdk12 and sdk14

robotjosh — Wed, 23 Aug 2017 22:12:20 GMT

It was the uart rx pin not pulled high, thought it was always receiving.

RE: internal rc slow clock problems with sdk12 and sdk14

robotjosh — Wed, 23 Aug 2017 15:18:13 GMT

I have also cut these traces on my dev kit and can see the code runs as expected. I am stumped why my design hard faults with invalid instruction when it appears to be the exact same configuration running the exact same code. Other code that only scans and advertises runs on my design as expected. Only if the firmware supports connections the code hard faults on startup.

RE: internal rc slow clock problems with sdk12 and sdk14

Jørgen Holmefjord — Wed, 23 Aug 2017 12:48:55 GMT

Yes, I have tested this on PCA10040 board with SB1/SB2 cut and SB3/SB4 soldered.

RE: internal rc slow clock problems with sdk12 and sdk14

robotjosh — Wed, 23 Aug 2017 12:27:10 GMT

Have you tested this on a device which does not have the low frequency crystal placed?

RE: internal rc slow clock problems with sdk12 and sdk14

Jørgen Holmefjord — Wed, 23 Aug 2017 12:18:46 GMT

Are you sure that you set the clock source in the correct place? In SDK 14, you can change the clock source using the sdk_config.h macros:

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

// <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 12
#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 7
#endif

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