I had a lot of trouble with various resonators (16 MHz on 16c74x).  Each
company said the resonator was fine if it worked in their CMOS inverter
circuit and they made no claims regarding operation with a PIC.  The
exception is muRata.  Go to their website, then follow the link to their
site in Japan.  They have a search engine where you can put in the number
of the chip you want to use with the resonator and it'll return the
muRata part number that WILL WORK.  They've actually characterized the
resonators with the various chips.

Thousands of resonators later, I've had good luck...

Harold


On Fri, 1 Oct 1999 20:29:42 -0700 Dave Johnson <djohnson@SIRIUS.COM>
writes:
> I have four identical prototype boards with PIC16F877s and 4MHz
> ceramic
> resonators (with built-in caps). Three of the four boards work
> great, but
> the fourth has startup problems. And since oscillators and crystals
> are
> still black magic to me, I'm a little clueless what to look for.
>
> Symptoms: sometimes it never comes to life at all when powered up,
> and
> scoping the resonator shows me a flatline. Sometimes it does come
> up, but
> usually after a delay. Sometimes just scoping the resonator, or
> touching
> pins around the resonator, kicks it into life, at least momentarily.
> (There's an led startup sequence so I can see it's progress, and
> sometimes it gets part way through then freezes, other times it
> starts up
> and keeps going.) Once it ran for a minute or so then just stopped
> in its
> tracks.
>
> Thanks for any debugging suggestions, this is an area I need to
> learn
> more about, obviously :-)
>
> Dave Johnson

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