nrf52810 custom board no Bluetooth signal

Hello,

Did you also remember to change the 32KHz source in your code? All BLE examples are configured to use the 32KHz crystal oscillator default, but as you don't have the crystal in your design you will have to select the internal RC oscillator instead. You can use the configuration settings below to select this clock source.

sdk_config.h:

// </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

// </h> 

Best regards,

Vidar

Hi Vidar,

You are right. Yes, i have changed the settings like this. that's why it's advertising(confirmed by turning on LED in my board and editing the example code). The problem, i mentioned above i didn't get any Bluetooth signal in my phone.

Thank you for your reply.

Best Regards,

Habib

Hi Habib,

OK, thanks for confirming. What about the 32MHz crystal? Have you verified that it is correctly loaded (capacitive load - see 64 MHz crystal oscillator (HFXO) for calculation) and if it meets the accuracy requirements for BLE (+/- 40 ppm)?

Best regards,

Vidar

Hi Vidar,

I need to check this part. i bought the nRF52 DK, and changed nRF52832 to nRF52810, everything is working fine. So, it confirmed, that in my custom board the part you mention has some problems. 

Thank you for your help.

i still didn't get it, how can i calculate PCB stray capacitance, and what should be my load capacitor value?

Best regards,

Habib

Hi Habib,

The PCB stray capacitance is likely negligible if you follow the recommended layout where the crystal is place right next to the nRF. What's important is that load capacitors are correctly sized for the load capacitance of your crystal (load capacitance should be listed in the datasheet).

Best regards,

Vidar