On Mon, 22 Dec 1997, Jason Wolfson wrote:

> Does anyone have any clever, low parts count
> methods of multiplexing 3 pushbuttons onto
> 2 port pins?
>
> Thanks
> Jason Wolfson
> Lipidex Corp
>
> jason@lipidex.com
>
PTM: First approximation: 74147.

If you only have one finger, you can do like this:

        + ------X----X-----X                    V  =diode
                |    |     SC                   Sx =switch
                V    V     V                    X  =connection
                SA   SB    X-X                  R  =resistance
                |    |     | |
                X----------X------------ PB0
                     |       |
                     X-------X---------- PB1
                     R       R
        - -----------X-------X
Here the SC switch gives the same code as SA and SB pressed together.
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PTM, pasi.mustalahti@utu.fi, ptmusta@utu.fi, http://www.utu.fi/~ptmusta
Lab.ins. (mikrotuki) ATK-keskus/Mat.Luon.Tdk                    OH1HEK
Lab.engineer (PC support) Computer Center                       OI7234
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