Hello,

I have a 16F690 I with a 4MHz crystal. As specified in it's datasheet, I use two 22pF caps (C1 + C2).

I'm building a time depend circuit (charger) where a +/- minute accuracy over 10 hours is not important.

Nevertheless, I'd like to know how to "calibrate" the crystal to make it more accurate.

I read this: http://ww1.microchip.com/downloads/e...tes/00588b.pdf and still don't know if I'm going to pull the trigger

Then, I found this: http://ww1.microchip.com/downloads/e...Doc/70054b.pdf witch looks a little more understandable (comprehensible?) to me.

Finally I read this one: http://ww1.microchip.com/downloads/e...tes/00826a.pdf.

I was looking for a "simple way" to check the crystal's accuracy.

Does anyone have this explanation for me?

I only have a cheap PC 20MHz oscilloscope so I don't expect to make lab measurements...