Can button be set to cause interrupt, and then it's functions changed?

[CuriousOne]

Can built-in timer used to count the time while circuit is on?

[Art]

That’s what DT’s Elapsed Timer does, yes, but if you want to use the portb.0 interrupt for a button as well,
there is a separate DT package. I forget the name of that, but someone will chime in. It allows multiple interrupt sources.