2/25/03 11:27:14 PM, Michael Reid <mikecreid@MSN.COM> wrote:

>Does anyone have any experience in using an A to D input with a ladder
>resistor array of 8 resistors and 8 switches to allow for the 8 switches to
>be used without taking up more than 1 I/O into the processor?

There are a couple examples on Microchip's site; the one I remember offhand was in the "tips and
tricks" document for the 12F629/675.

>If the resistors are all 1k in value then the input voltage will correspond
>to whichever button is pressed?  Is this a practical route to explore?
>
>We are designing a keypad for a control system and I/O's are at a premium.
>We need a 1 or 2 color LED per switch so that will use a mess of I/O's.

Sounds reasonable, but read the application notes; you'll want to watch out for noise pickup and for
boundary ambiguity.

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