al smith wrote :

> Yes...and it does turn on if I drive it from PortD, just
> PortB doesnt seem to like it.

Again, *are* you seeing 0V in the gate at the same time
as the PortB is connected ?

> I wonder if the internal PUP on
> the port might be causing leakage of some sort.

Doesn't matter. If the pin is at 0V, it is at 0V. It does not matter
a bit whatever else is connected there. As far as the MIC is
concerned, it's just a point at 0V. That's all it sees. The MIC
can't "see" the difference between a short to ground and
a PIC pin driven to 0V.

> The PIC is running off of a 3.3V supply, while
> the FET source is tied to a different (totally different rail) 5V.  In other
> words, the 3.3V is from one DC/DC while the source is another totally
> different DC/DC, not even the same input source.  Of course the grounds are
> all common.

With a common ground, I think it should work. And it does with
PortD, right ?

> And nothing else is tied to the PIC pin, just the gate.

> Speed wise, I am inside MPLAB, using a
> view window and overriding the values by typing in a new value,
> so its about as slow as it could be.

Could you clearify how your setup look like ?
Some kind of debugging mode ? Is this not run using
real code in the PIC ? Could this just be different way
of MPLAB in handling the ports ?

And still, did you, or did you not, measure 0V on the
PIC/MIC pins when they are connected together ?
I mean in real, not just that the view window says so...


Jan-Erik.

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