> You remember in the movie "Michael" when the angel Michael said "you can 
> never eat too much sugar"?

Excellent example.

> Well you can never have too much GND plane, and that includes copper 
> pours.
>
> BUT... unconnected copper pour fragments will actually hurt, not help, an 
> EMI situation. Make sure those
> pieces are actually GND.

Okay.  Thankfully, pcb design software is really good at removing free 
copper automatically.

> Did you put tiny caps on any long runs? Even caps as small as 5pF seems to 
> stop a PIC from capturing noise
> through a long trace. Just a thought.

No kidding?  Please tell me at which end of the run is best, or right in the 
middle if it matters?  Makes sense to put it right before the input pin. 
The longest trace on my board is only about 2 1/2" so unless you recommend 
otherwise I'll probably leave them off.

> 4Mhz is so slow that you won't radiate anything either. HINT: if you can't 
> hear any noise, chances are great that
> the PIC won't capture any, either.

I think what my real problem is that on the previous revision I made a 
bonehead compromize and left the crystal unprotected & close to the edge of 
the board.  That's fixed on the new revision and I'm trying to include any 
other noise trick I can think of, within reason.  Copper pour is free.

Lots to be learned here.

> You are on the right track.

Pun intended???  :o)

Thanks for all your help, Bob.

Rick



-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist