Vmer Yalh} wrote:
> 1. If I touch (with my bare finger) to the cap that is connected to
> the RB7 pin of the pic (where the xtal's one pin is connected) the
> unit does not wake up

The power level of some 32Khz crystals is deliberately very low because they
are meant to run a few years in a wrist watch on a single tiny battery.  As
a result, the signals are high impedence and easily disturbed.  The best
answer to this is "don't do that".

> 2. If I "breathe" on the same cap above.
>
> ...
>
> I also did this test right after brushing so probably
> this is not because of my breath! :-)

Doh, there goes my first thought.

> The cap is 22pF.
>
> Why does this happen?  Bad board design?

Probably not.

Is the crystal specified with such a large value?  22pF is usually about
right for "normal" crystals, but these low power watch crystals often want
half that or less.  The extra capacitance may be attenuating the signal to
where it barely oscillates.  The extra leakage from the humidity may be just
enough to kill it.  Try removing the cap from the oscillator in pin side of
the crystal and see if breathing on it still kills it.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body