I did not see the original post, so I don't know if S1 and S2 presses were
to be treated exactly the same.  Since it refers to '4 states', I believe
they s/b different.

You would think that a 1:2:4 ratio of resistances would be the better than
1:2:2.  With 1:2:2 I believe you will not be able to differentiate between
an S1 and S2 press.

Joe

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of David VanHorn
> Sent: Thursday, November 20, 2003 2:56 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: ] Multiple buttons on one pin
>
>
> At 12:28 PM 11/20/2003 -0800, Don Taylor wrote:
>
> >On Thu, 20 Nov 2003, David VanHorn wrote:
> >>           /-S1--+-S2--\
> >>           |     |     |
> >> Pin-----+-+-ra--+-rb--+-rc----Ground
> >>         \------------C--------Ground
> >>
> >> So I have four time constants:
> >>
> >> C*Rc
> >> C*(Rc+Rb)
> >> C*(Ra+Rb)
> >> C*(Ra+Rb+Rc)
> >>
> >> I'd like to get as much spread as possible between the time constants.
> >> (within reason!)
> >
> >If you can give a little more precise description of what you want
> >maximized I have some horsepower here to grind for a solution.
> >But I don't know what criteria you want to use.
>
> I'm looking to maximize the difference in the R/C time constants
> in those four states.
>
> Ra=10, Rb=10, Rc=20 is the best I've hit on so far, with 50%
> minimum delta.
>
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