On Wed, 2011-01-19 at 12:58 -0800, Bob Blick wrote:
> Weird, could I have a bad PIC? But it was one that had been kicking
> around, so I figured it could be. I grabbed a new chip and it worked
> fine.
>=20
> Last night I took a few extra minutes to review my code in preparation
> for doing a PC board layout and realized nothing was connected to GPIO4.
> I had the IR receiver going to pin 4, which is GPIO3 and also MCLR. In
> my sleepy head at one point I must have seen pin 4 on my breadboard and
> typed GPIO4 in the code instead of GPIO3.
>=20
> Since MCLR is input-only, it didn't short out the IR receiver, and the
> pin that was looking for the signal was just getting a little stray
> coupling and that's the only reason anything worked. It didn't work the
> same on both chips because the leakage of the two was different.
>=20
> I changed the pin definition and the TRIS line to reflect the actual
> configuration, and both chips worked when programmed.
>=20
> So the huge amount of crosstalk in the solderless breadboard was the
> only reason it sort of worked.
>=20
> Boy, did I feel dumb!

You shouldn't feel dumb at all! I read this and was impressed that
instead of going into "dead fish" territory, you debugged the problem
and found a solution.

I'm amazed how many engineers I encounter that would have thrown up
their hands and walked away when confronted with this sort of problem.

Yes, setting for the wrong pin was a "dumb" mistake, but it's not
something I'd feel "dumb" about in your shoes.

Congrats on figuring it out.

TTYL

--=20
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