The OP could use the 74HC597 to serially expand the number of inputs.
Usually it would need three I/O pins, but with a clever trick it is
possible to use just two.
It is possible to expand the input pins to virtually any number, in
multiples of eight.

Isaac


Em 13/09/2015 20:13, IVP escreveu:
>>> Thanks.   I am only looking for 5 bit accuracy.
>>>
>> That might be asking a bit much - not from the PIC, that's easy
>> enough - from the person.
>> 5 bits =3D 32 position values. Typical pot has about 270 degrees
>> of travel. 270 / 32 =3D ~8.4 degrees.
> My nephew has a guitar effects box, and one of the selectors
> looks rather like that on a DMM, but is actually a pot with 10
> detent positions between fully CCW and fully CW, giving 12
> distinct settings altogether. The knob is spring-loaded against
> a ring of bumps in the case plastic
>
> Maybe you can make something with a slotted disc and a ball
> bearing and a spring or other bits and pieces. 32 values is going
> to be tricky though.
>
> 10-turn pot ? With vernier ?
>
> Analogue TVs had slide pots with a screw thread for tuning
>
> Two thumbwheel or BCD switches, 10s and 1s ?
>
> How about an optical encoder, bought or made. You could
> print a scale on a transparency. Perhaps 5 rings to represent
> 5 bits in a simple binary code, or 1 ring of stripes to generate
> pulses to count
>
> There are many variations of digital calipers, protractors and
> rulers you could take apart for a very fine position sensor
>
> Pehaps hack an optical mouse. Draw a circle on the screen
> now with it. Can you potentiometerise that ?
>
> All options have drawbacks - accuracy, precision, consumption,
> reset on power-down, cost, fiddliness etc
>
> Joe
>
>
> -----
> No virus found in this message.
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> Version: 2015.0.6125 / Virus Database: 4419/10635 - Release Date: 09/13/1=
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>



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