> >Yes, there should be at least a voltage sensitive reset circuit on
> >any micro in just about any practical application, particularly
> >automotive. Watchdog is next on the list of most important things.
>
> Is that so...
> A watchdog is not important (My opinion) others will proberably not share
> this same recourse but I will give you my reasons especialy for the PIC...

OK Dennis I beleive you, I was probably more considering '51 stuff
than PIC's. Wouldn't it be great if we could just switch on the power
to any micro and it went forever without getting upset and requiring
a reset?

All your points are good but it prompted me to think why I would
still use a watchdog with a PIC. Not major points, just little
thoughts really...

I don't have extreme confidence with the oscillator startup on PICs.
Seems to me that many PICsters have had some kind of bad
experience with getting an external crystal to startup during
development which makes me a little suspicious. Whatever the
precise reasons behind this occuring in the field, if it ever did
happen a watchdog reset might get it going again (wouldn't it?)

Similarly, people have at times talked about the brownout detect
not being 100% reliable for all Vcc rise and fall rates or whatever
other reason. I'm happy enough to solely rely on the internal reset
and brownout functions, as long as I have the watchdog for backup.

How many times should we have CLRWDT in our code? Your right -
 only once. Even though I sometimes do it myself, any more than
once is asking for trouble.

Thanks for sharing your thoughts which we can all consider in our
designs.

Brent Brown
Electronic Design Solutions
16 English Street
Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile: 025 334 069
eMail:  brent.brown@clear.net.nz