BLE not starting in custom Board of NRF52832

RE: BLE not starting in custom Board of NRF52832

Sigurd — Mon, 29 Jan 2018 10:24:00 GMT

Great to hear that the issue is now resolved.

The HFCLK is either running on internal oscillator (HFINT) or crystal oscillator (HFXO). The TIMERS can be using HFINT or HFXO, but the RADIO need to use HFXO.

Q: If we start the clock using NRF_CLOCK->TASKS_HFCLKSTART = 1; then it is mentioned in the datasheet that HFXO will get started instead of HFINT. This means even the timers are running on the external oscillator. Isn't that correct?

A: Yes, that is correct. You can check if the HFCLK is using HFINT or HFXO by calling the function nrf_drv_clock_hfclk_is_running(). The function will return true if you are using the HFXO.

RE: BLE not starting in custom Board of NRF52832

soumil — Wed, 24 Jan 2018 07:41:48 GMT

Hey sigurd, we realized that the orientation of the High-Frequency clock was not correct which you pointed out as well. We fixed that and BLE is now working fine. We are very confused on how the timers are running fine but the radio is not. If we start the clock using NRF_CLOCK->TASKS_HFCLKSTART = 1; then it is mentioned in the datasheet that HFXO will get started instead of HFINT. This means even the timers are running on the external oscillator. Isn't that correct?

RE: BLE not starting in custom Board of NRF52832

soumil — Tue, 23 Jan 2018 07:10:48 GMT

Hey Sigurd. I tried all the approaches you mentioned but the device is still not visible. Could it be because of load capacitance of the external crystal or the maybe the Antenna not working?

RE: BLE not starting in custom Board of NRF52832

Sigurd — Thu, 18 Jan 2018 10:30:11 GMT

The HFCLK controller supports both internal oscillator (HFINT) and crystal oscillator (HFXO). So it could be that your timers are running on the HFINT. The RADIO need to use HFXO. You could try to debug and see if get any error-messages or if the code is stuck in a loop somewhere. See this post on debugging.

RE: BLE not starting in custom Board of NRF52832

soumil — Thu, 18 Jan 2018 10:23:07 GMT

Thanks Sigurd. We are actually using High Frequency clock in the code before doing any BLE activity and the timers are running fine which tells us that there is no problem with the HFCLK. Hence, I think Low Frequency clock could the reason. Let me know if there is something else to try.

RE: BLE not starting in custom Board of NRF52832

Sigurd — Thu, 18 Jan 2018 10:15:16 GMT

If the above changes does not help. Then you should check that the HF crystal is correctly mounted, i.e. not turned 90 degrees.

You could also add this code at the start of main(), and check that you are not getting stuck in the while loop. If you get stuck in the while-loop, then you have some problem with the HF crystal.

  // Start HFCLK from crystal oscillator. The radio needs crystal to function correctly.
  NRF_CLOCK->TASKS_HFCLKSTART = 1;
  while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

RE: BLE not starting in custom Board of NRF52832

soumil — Thu, 18 Jan 2018 10:08:48 GMT

We do have a low-frequency clock in the circuit. I have tried the approach which you have mentioned Andre. I will change the settings as recommended by Sigurd and try it out.

RE: BLE not starting in custom Board of NRF52832

Sigurd — Thu, 18 Jan 2018 09:58:08 GMT

Note that LFCLK Synthesized from HFCLK draws alot of power. If the board does not have a LF crystal, the recommended config is:

#define NRF_CLOCK_LFCLKSRC      {.source       = NRF_CLOCK_LF_SRC_RC,            \
                                .rc_ctiv       = 32,                                \
                                .rc_temp_ctiv  = 2,                                \
                                .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM}

RE: BLE not starting in custom Board of NRF52832

Andre — Thu, 18 Jan 2018 09:45:52 GMT

The low frequency clock can be a problem. If your custom board does not have a low frequency crystal connected, the code will wait forever for it to start. This is not a hardfault, just a while loop with a condition that never changes.

If you want to use a board without low frequency crystal, you should select another low frequency clock source. Try something like

#define NRF_CLOCK_LFCLKSRC      {.source       = NRF_CLOCK_LF_SRC_SYNTH,            \
                                .rc_ctiv       = 0,                                \
                                .rc_temp_ctiv  = 0,                                \
                                .xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM}