John Piccirillo <PICLIST@MITVMA.MIT.EDU> wrote:

> what kind of crystal should I use.  Catalogs list microprocessor
> crystals, besides frequency, as TTL or CMOS levels, and loads as
> "series" or for a particular capacitance, eg. 20 pf. Does it make
> a difference and do I use external capacitors?  I have the PIC Data
> Book but don't recall it specifying details about the crystal.

John:

It does make a difference, and you should be using a parallel crystal
with external capacitors.  The Data Book actually does say this, but
you have to read the whole section to find the information.

I don't really understand, actually, why so many people on the list
are using crystals at all.  Ceramic resonators are accurate to within
0.5% or so, and they're easier, cheaper, and (if you buy them with
internal capacitors) smaller than crystals.  Panasonic resonators
with built-in capacitors are available from all the major catalog
distributors.

-Andy

Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499