Check oscillator/Xtal accuracy - how to?

[Darrel Taylor]

If you don't happen to have a frequency counter.
You can put a 32768hz watch crystal or DS32KHZ compensated oscillator on TIMER1 and use it as the time base to measure your system frequency.

I trust it more than frequency counters, which in the Mhz ranges can be off by several Khz, depending on the quality of the counter.

An example of the technique can be found in Microchip's AN244.
Although it's geared towards calibrating the internal oscillator, the concept is the same for externals.

http://www.microchip.com/stellent/id...pnote=en012071

[flotulopex]

Thank you Darrel.

I should have started searching there... Lots of infos to find in the application notes ;-)