nRF52840 BLE doesn't work but no errors

[dmitry.kurochkin]

Hello,

Problem: BLE doesn't work on a OurBoard with nRF52840 (Schema1).

1) BLE example is working DevBoard (can see BLE server by scanner). On the OurBoard the examle is running without any errors, but BLE server is not visible by scanners.

Example:nRF5_SDK_15.3.0_59ac345/examples/ble_peripheral/ble_app_hrs.

2) We also run from internal clock instead of external, the same result (on DevBoard - working, on OurBoard - not working).

3) All another peripheral is working on OurBoard.

4) This same problem on 4 pieces of OurBoard

Please suggest what can be and what should check?

Thanks.

[ketiljo]

What's the CL value of the 32 MHz and the 32 kHz crystals you are using? You can calculate the values of the load caps:

Ccap = CL * 2 - Cpin, where Cpin = 4 pF. Round down to the nearest standard value. 12 pF load caps are good only for crystals with a CL value of 8 pF

[dmitry.kurochkin]

Thanks for the reply

We changed the load caps that you suggest on 15 pF, but this does not work too.

The same antenna and circuit of clock works in our other project with nRF52832.

[hmolesworth]

Maybe the 32kHz crystal has an issue, so worth trying not using the 32kHz crystal to test that possibility. Add something like this at the start of sdk_config.h:

// add "_NO_32_KHZ_CRYSTAL" to project preprocessor (or just comment out)
//#if defined(_NO_32_KHZ_CRYSTAL)
#define NRFX_CLOCK_CONFIG_LF_SRC         0
#define CLOCK_CONFIG_LF_SRC              0
#define NRF_SDH_CLOCK_LF_SRC             0
#define NRF_SDH_CLOCK_LF_RC_CTIV        16
#define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV    2
#define NRF_SDH_CLOCK_LF_ACCURACY        1 // <1=> NRF_CLOCK_LF_ACCURACY_500_PPM
//#endif

In bsp_init use this:

   APP_ERROR_CHECK(nrf_drv_clock_init());
   nrf_drv_clock_lfclk_request(NULL);

This works on my boards which don't have reliable 32kHz crystals

[dmitry.kurochkin]

We found the issue in 32 MHz crystal circuit. Now BLE is working.

Thank you.