Internal RTC reliability?

N

NickViz

Member
Hi all,

our project highly depends on RTC. We added a battery to teensy 3.1 to get internal clock running during power outages. Usually it's powered from USB.

We have two items in field running for approximately a month now and got a problem with one of them: yesterday was power outage for 3 hours. After that the time register seems to got a random value (the calculated date was 31/08/2057). I checked battery state by disconnected unit for 5 minutes from USB - no problem.

Of course it can be bad battery connection, but I'm quite worried if it happens again. I'll get that unit back and investigate it, but my question to all - does anybody make/use a clock on Teensy and do you have any issues with it's stability? Not the time accuracy, but the total time loss.

I wonder if I need to add a capacitor or something to improve RTC power source switching capabilities...

Thanks in advance,
Nikolai
 
I have yet to have a problem using the standard dual Schottky diode approach where the RTC power pin is fed either by the on board 3.3v bus or a CR2032 battery.

The only times I have had issues re RTC operation is when trying to start the teensy after freezing it to -40*C or below. Presumably the crystals (either the MCU or the RTC one) were having a bad hair day at those temperatures.
 
Last edited:
Problem solved!

Happy to report that the error was in the poor battery connector soldering. So, the RTC in Teensy seems to be stable :)
 
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