You want parallel crystals, and you take the spec they give for loading cap=
acitance, double that, subtract about 5pf, and use that value or as close a=
s reasonable for the loading caps.

Do not use 22pf caps on a 22pf crystal.  The bad news is that it will proba=
bly run that way.  Why that is bad news is left as an exercise for the stud=
ent.


Nathan House <nathanpiclist@gmail.com> wrote:

>I'm making a board for a PIC18 microcontroller and have a few
>questions about crystal selection. Firstly, on Digi-Key, under the
>heading "Load Capacitance," there is the option "Series" and then a
>bunch of different capacitor options below that. Will a series crystal
>work, or should I get one that uses capacitors? One other question I
>have is regarding the crystal frequency. Most PIC18 microcontrollers
>(all of the ones I've used, at least) have a PLL built in, so a
>variety of different crystals can be used with the same resulting
>system clock speed. If the PIC I'm using has a PLL that would allow me
>to use, say, a 4MHz, 8MHz, 12MHz, 20MHz, or 24MHz crystal, is there
>any reason to use a higher speed crystal as opposed to a lower speed
>one?
>
>Appreciate your advice!
>
>Nathan
>
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