Strange start up behaviour, maybe temperature related?

I’m getting to grips with my Core and have noticed some strange behaviour when I power it up (from USB).
From cold the core doesn’t go through the usual LED sequence at start up. Instead it pulses fast white a few times, then briefly sticks at solid white, before repeating the cycle ad-infinitum. The blue LED (on D7) flashes briefly too each time the sequence repeats. It looks like the Core is failing to start up correctly, maybe rebooting / resetting they trying again.

This behaviour is repeatable no matter what USB port / USB power supply I use. I’ve also tried a selection of USB cables.

The only solution I have found is to warm up the Core under my desk lamp for a few seconds (or in the exhaust of my sweating laptop!). After a quick warm up it starts up fairly normally, but generally gets stuck flashing green. A further reset gets it fully running & subsequent restarts, either via the reset button, or power cycle are normal.

It’s not particularly cold in my study - say 20C. Are there any known issues relating to startup & temperature, or do I maybe have an iffy Core?

I’ll throw mine in the freezer and see if the same thing happens.

It could potentially be a bad solder joint, that when warming up the board is expanding the board/joint and it makes contact.

When the board is cold (20C), can you see if just pushing on it lightly (like down on the CC3000) changes the behavior?

Thanks for the suggestion @BDub, I’ll give that a try next time it’s cold and post the result…

Pulled mine out of the freezer and powered it up via USB. Flashed White alittle longer than normal it seemed but started up normally otherwise. The temp sensor reported back to be 10 degrees F.

I threw back in the freezer and I’ll test again in another hour and see if that does anything.

I’m not sure which countries people lives and what units they are used to, but 20C is very common room temperature in winter and nowhere near freezer temperature. It is ~1/3 colder than skin so with metals it could feel coldish but really isn’t even near a problem temperature range for (unbroken) electronics.

Have you tried flashing any updated firmware and observed the issue after?

Hi @clarkeshire

I agree with @BDub–I think you have cold solder joint, which is an intermittent connection on the board.

Another way to see that’s the problem is tap gently on the board with your finger or the eraser end of a pencil and see if you can make it fail. Usually you can for a cold solder joint. Just don’t go nuts hitting it–be gentle.

After extended 10 Degree F freezer temp testing the only thing that I did notice is that the White LED flash on power up can take almost twice as long but it then goes to flashing green and breathing Cyan as it should.

It looks like a cold joint is the culprit here. The problem is readily reproducible by cooling in the fridge for a few mins, pressing on the CC3000 doesn’t fix it, tapping on the corner nearest the D7 pin might have done the trick on one occasion, but warming it up reliably gets it going. Looks like I’ll need to swap my Core out, so I’ll get in touch with Spark via email.

Thanks for the all the advice and suggestions!