At 01:07 PM 12/31/98 -0600, John Payson wrote:
>|Good idea ! Now, how can one chop AND switch the current with RA4 + coil ?
>
>What about using a cap for negative voltage generation?  Maybe
>use four pins total, wired like this:


|The input protection diodes will kill you. You'll never get it past about
|.7V below the rail, and you could easily throw it into SCR latchup.

The goal was to measure exactly how far below the rail the diodes
would let a pin go with a small amount of current.  The resistors
are there to limit the current to either 10uA or 100uA; since the
PIC's diodes are designed to handle miliamps' worth of current with-
out latch-up or other problems, I would think that inducing latchup
with 100uA of current should be well-nigh impossible.


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