custom hardware nRF52832 hangs during softdevice initialization

RE: custom hardware nRF52832 hangs during softdevice initialization

Aaron — Tue, 17 Mar 2020 15:33:59 GMT

Yep, that worked. Really strange the same thing happened to 3 different boards. I need to look at the xtal on an oscope to make sure this isn't anything else.

Thanks for your assistance!

RE: custom hardware nRF52832 hangs during softdevice initialization

Kenneth — Tue, 17 Mar 2020 11:41:00 GMT

Have you tried to solder back the "defective" xtal? I think it might have been some margin solderbridge below the crystal.

Best regards,
Kenneth

RE: custom hardware nRF52832 hangs during softdevice initialization

Aaron — Mon, 16 Mar 2020 20:33:57 GMT

Ok, I replaced the xtal with the same type and it works.

However, I'm still unsure how the boards are failing. This is for a product, so I'll need to determine why. All I did was hot air off the regulator and the board's xtal fails. To fix the boards, I hot air the "defective" xtal off and hot air the same type back on and it works.

Any idea why this would be happening?

RE: custom hardware nRF52832 hangs during softdevice initialization

Kenneth — Mon, 16 Mar 2020 16:03:00 GMT

[quote user="aawcorn"]So I guess this points to my 32kHz xtal either being defective or out of spec?[/quote]

Yes it's defective, I suggest to check that there is no short (e.g. solderbridge) to ground and try a different/new 32kHz crystal.

The NRF_SDH_CLOCK_LF_RC_TEMP_CTIV can't be used with external crystal, so it should be 0 when using external crystal.

Best regards,
Kenneth

RE: custom hardware nRF52832 hangs during softdevice initialization

Aaron — Mon, 16 Mar 2020 15:28:44 GMT

Another thing I'm noticing, on the good boards I use these settings in sdk.config.h and everything works fine.

#define NRF_SDH_CLOCK_LF_SRC 1
#define NRF_SDH_CLOCK_LF_RC_CTIV 0
#define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 0
#define NRF_SDH_CLOCK_LF_ACCURACY 7

When I change NRF_SDH_CLOCK_LF_RC_TEMP_CTIV to 2 (from 0), I get the same fatal error as the bad boards.

Why does changing this value have an affect if I'm set to use external xtal (LF_SRC 1)? I'm not even using the internal RC.

RE: custom hardware nRF52832 hangs during softdevice initialization

Aaron — Mon, 16 Mar 2020 14:28:14 GMT

I just tried your first suggestion with both boards. With the board that isn't working (no regulator), the LFCLK does not start and goes into the else statement. With the board that is working, the LFCLK does start and goes into the if statement.

I also tried your second suggestion and the internal RC does in fact work on the bad board and goes into advertising, but when I set LF_SRC to 1 again, it goes into fatal error.

So I guess this points to my 32kHz xtal either being defective or out of spec? I don't think my rework on the PCBs affected anything. It's odd because both boards are the same and one just has the regulator removed, that is it. I've tried on multiple boards with the same result.

RE: custom hardware nRF52832 hangs during softdevice initialization

Kenneth — Mon, 16 Mar 2020 08:44:49 GMT

Have you tried to start the external 32kHz crytal manually without the softdevice, just to confirm it works as intended? You can try:

	NRF_CLOCK->LFCLKSRC = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
	NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
	NRF_CLOCK->TASKS_LFCLKSTART = 1;
	
	// Wait for the low frequency clock to start
	nrf_delay_ms(1000);
	
	if(NRF_CLOCK->EVENTS_LFCLKSTARTED == 1)
	{
	// hurray there is an external LFCLK present.
	// you can set external LFCLK when enable softdevice
	NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
	}
	else
	{
	// no external lfclk present, you can use internal LFCK when enable softdevice
	}

Also, can you try to use the internal RC for test (instead of external 32kHz) when enable softdevice? For instance by change in sdk_config.h:

#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