It would seem to me that this would be very difficult to achieve reliably
with NO external components, but with about 2 or 3 components, it could
be done properly. If you have a pull up resistor of about 2 Meg from
the PIc pin to +5v, then toughing a finger between this input and GND
should pull it low enough to change the state. THe only remaining problem
is that of ESD protection and keeping the circuit from being thrown off
by picking up stray signals. A .01 uF cap from the pin to ground should
help with the stray signals. The input protection diodes might be good
enough for some applications, but you might also add a 6 or 7 volt zener
diode, reverse biased, to ground.At this point, the same software
debouncing routines which work for bushbuttons would probably work on
this, too.

Sean


On Wed, 15 Jul 1998, John Haggins wrote:

> Hi,
>
> Anyone got code to make a PIC input touch sensitive with no external
> components?
>
> i.e. if you connect a wire to an input, the PIC "knows" when you touch the
> wire.
>
> Thanks!
>