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Charging - only when on?


My two SCK2.1 do not (or no longer?) charge when off - only when sensing. By this I mean the light indicating battery charging/state isn’t visible/on when the device is off and it is plugged in to a powered USB port.

I’m putting “no longer” in brackets because I’m not 100% sure they ever did - but I thought they used to.

Or is it charging when off… but provides no indicator light?

I feel maybe my assumptions or memory is wrong. I’ll do some further testing and update.

Assuming the SCK2.1 can charge while off and the indicator light should come on…
I first suspected it may have been interference on my part with customizing the firmware but I’ve reverted to SAM 0.9.8 and the problem persists.

Am I correct the SAM firmware controls the battery behaviour, not the ESP?

I’ve also tried to revert farther back to SAM 0.9.7 and SAM 0.9.6 but the problem persists. This suggests it’s a hardware problem or cable/power supply.

There’s been some issues with charging in the past. One discussion/documentation I came across notes that “it is probably worth trying with another USB cable”.

I have tried multiple cables and multiple power supplies (e.g., PC, 2A power supply) and none seem to work when the device is off.

I’ll get back regarding further testing.


Hmm it seems that it is charging when off, just no indicator light comes on.

Good to know - I think I just had a false memory of indicator lights coming on when off but charging.


Hi cyrille

I believe you are not correct to say the samd controls charging. I believe samd monitors charging which is handled entirely in hardware.
“Pedantic?” If so sorry.
In any case think the ADC pin is employed to read battery voltage; and it gets reported to the UI.
I also think the led color reflects charging, but not sure how it can do that if the samd is asleep. The LED color also shows when the kit is running on battery alone.

But the esp does not get involved at all, except as a consumer.

Hi @bryn.parrott ,

Thanks, exactly the SAM monitors and does not control - this was my problem in conceptualizing the problem.

I think at some point I had a flat battery and though it had been plugged in (perhaps a bad cable in that case or just not plugged in properly as my enclosure is a bit tight) and started becoming insecure about it charging when off.



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