Question on crystal selection: parallel vs series cut

[khufumen]

Thanks for your help! The PIC is going to be used for serial communication at a 9600 baud rate so I should be good. I was not aware of the critical role that these small capacitances played in the crystal's performance. (Now I know) That crystal oven seems like an interesting idea for possible future timing applications. Thanks again.
Eric

[Paul]

Despite what people may think about crystals and their stability issue, as with all things, high tolerance, good stability and frequency stable crystals can be purchased at a price. Most crystals that were designed for standard microprocessor based applications were never intended for high stability / accuracy apps. These crystals tend to have a frequency stability range between 250ppm - 50ppm / C.

I purchased a 10Mhz crystal not so long ago that has a stability factor of 1ppm/C. At 10Mhz, it drifts 10Hz per C, which for accurate timing applications would be more than enough.

Search through electronic suppliers catalogues for crystal specs and you should see what I mean.

Paul.

[Michael Wakileh]

EEVblog #61 - Crystal Oscillator Drift http://www.eevblog.com/episodes/
may be worth watching