Hi,

Also Microchip has the tips&tricks doc which describes such possibilities
(tips 5, 6 and 7):

http://ww1.microchip.com/downloads/en/DeviceDoc/40040C.pdf

Regards,
Tamas


On 6/29/07, Marcel Duchamp <marcel.duchamp@sbcglobal.net> wrote:
>
> Ariel Rocholl wrote:
> > Hi all,
> >
> > I have only 1 pin available in a PIC16F micro but need to read 5-10
> > momentary buttons, and do not want to use any other additional external
> IC.
> > I figured out a way to work this out using 1 single A/D pin to
> differentiate
> > each button from the rest, provided I have different R-R bridge for each
> > button, therefore if no button is pressed the A/D should read 5V, but as
> > soon as a button is pressed, a R would move that to, say, 2.8V. If all
> the
> > resistor combination are different and I can work with at least
> > 0.25Vdistance between them (
> > e.g. 0.25V, 0.50V, 0.75V, 1V, etc), looks like a robust and solid
> solution
> > to me.
> >
> > Only drawback I can see is no multiple buttons can be pressed at a time
> and
> > give a valid value, but this is not a requirement.
> >
> > Do you see any problem with this approach? Anybody used something like
> this
> > before? Any other option you can suggest for multiple buttons, 1 pin and
> no
> > additional circuitry?
> >
> > Thanks in advance.
> >
>
> I used this technique to read a 12 position rotary switch; it worked
> very well.  Of course, this is a bit different from reading separate
> pushbuttons.
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