connection problem with nrf52832

[Berker]

Hi,

I tried, ble_blinky example on DK, it works well. Also advertising interval 40ms on nrfconnect mobile app,this is consistent with SDK. 

Now, i try same example with custom board( i'm sure custom board work properly), nrfconnect app shows adevertising interval as 400ms, this is false, another bad news, the connection never be successful. 

My antenna design is not perfect,i know. It is seen by nrf connect app RSSI value. What is the reason of bonding or connection problem. Connection logs,say 0x85 gatt arror also. 

Best Regards

Berker 

[Sigurd]

Hi,

What RSSI value did you measure on the custom board?

What clock source are you using for the SoftDevice?

Could you try this configuration for the LF clock source: (from sdk_config.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_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
#endif

[Berker]

Hi Sigurd,

thanks for this useful reply. 

Adv interval fixed  now and 40ms as expected. Also connection established most of the time and i can blink led. 

The problem is related with my 32MHz oscillator? Or what? 

Sigurd said:

What RSSI value did you measure on the custom board?

RSSI is not good, -70,80dBm in about 20-30cm distance. Is this related my antenna and board design,is it true?

And sometimes connection not bonded, the reason of this RSSI? or about your reply? 

Thanks

[Sigurd]

Berker said:

The problem is related with my 32MHz oscillator? Or what? 

If changing the value of NRF_SDH_CLOCK_LF_SRC from 1 to 0 worked, then this indicates an issue with the external 32.768 kHz crystal. It could be caused by wrong values of the load capacitors(C11/C12), bad soldering and/or incorrect value of the specified clock accuracy.

Berker said:

And sometimes connection not bonded, the reason of this RSSI? or about your reply? 

This could also be caused by issues with the 32.768 kHz crystal.

If you want us to review your custom board design, I would recommend that you create a new case, where you upload the PCB layout/gerber files and schematic, and we can maybe help with some improvements to the design.

[Berker]

I didn't insert 32.768kHz crystal on custom pcb. As i know, that for RTC. I only insert 32MHz crystal through XC1/XC2 pins. 32.768kHz pins P0/P1 used for another purpose on custom pcb. Is there a wrong thing? 

[Sigurd]

Berker said:

Is there a wrong thing?

No, that is OK. You can use the internal 32.768 kHz RC oscillator, but it's important that it's correctly configured. (NRF_SDH_CLOCK_LF_SRC 0, NRF_SDH_CLOCK_LF_RC_CTIV 16, NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 2 and NRF_SDH_CLOCK_LF_ACCURACY 1).

[Berker]

Ok,thanks 

I will try some clock configurations.

Maybe another topic,but if you can help, I will be pleased

I use DK while programming custom board. I try loading ble_blinky example to custom board,but DK also loaded with blinky_example. Mobile app shows 2 advertising devices one custom board,another one DK. I only want to load custom one.

How can i solve this?

Best Regards 

[Sigurd]

Then the DK was probably already flashed with the ble_blinky example before you programmed the custom board. 

When the custom board is powered, the programmer on the DK will detect the supply voltage of the custom board and program/debug the target chip on the custom board instead of the on-board nRF52832.