Using The Propeler To Monitor Analog Switches

beazleybub

Hi,

I'm new to the propeller and have some questions about I/O.

I would like to propeller to monitor a fairly large number of analog contact switches using PollIO. I'm trying to accomplish this using as little of the props pins as possible to read these inputs. Can anyone suggest a way to do this?

Thanks


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How can there be·nothing? Nothing is something!

Mike Green

What do you mean by "analog contact switches"? Contact switches are digital in nature. The switch is either closed or open (or bouncing between those states).

If you have a large number of contact closures, you could do the same thing that is done with Stamps, use a 74HC165 parallel to serial shift register. You'd have up to 8 switches per 74HC165 and you could cascade them for more. Each string of shift registers would need to use 3 Prop I/O pins (clock, data, shift vs. parallel load). You could run them from the same 3.3V used by the Prop.

beazleybub

Hi Mr. Green!

Pardon me, I speak ( Or write for that matter ) the way I see things because I'm not too keen on proper lingo [noparse]:)[/noparse]

I'm aware most switches are either·0 or a 1 in logic. I should have said a mechanical switch.
I appreciate your 74HC165 suggestion. That's exactly what I was looking for! I had left out I would be using I2C.

Thank you very much. You are as usual a great asset and teacher·to the forums.



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How can there be·nothing? Nothing is something!

Post Edited (beazleybub) : 5/9/2010 1:35:13 AM GMT