Hi Guys,

I'm looking at running code at set periods over time and would like the timing to be as stable as possible.

I have looked at IntervalTimer and elapsedMicros and on the 4.1 I am using here I get around 3ms drift in a minute.

I looked at the output of AnalogWrite and get the same error in frequency.

So I'm guessing this is just the crystal used being inaccurate? 1 part in 20,000 seems pretty bad though?

Is this the expected accuracy?

Any help would be greatly appreciated.