16F628 Internal clock

[srob]

I wish to add a frequency counter to a square wave generator (20Hz to 3kHz, TTL) using the COUNT instruction, and to keep it really simple was going to use a 16F628, 8x1 LCD and 100nF decoupling capacitor!

Intended to use the internal oscillator and tweak the count period to get a fairly accurate reading (with 3%?).

But wondered if the internal clock drifted with age, temperature, etc?

Thanks

[mister_e]

Yup, that's the bad part. The internal OSC will shift with temperature, wind direction, Gas price and almost everything else. If you need accuracy, use a Crystal.

[srob]

Thanks. Will just have to had a crystal to the parts list!