[sdiy] Opto-switch Kybd (was Reed and Switch)

[Ingo Debus]

Am Freitag, 12.12.03 um 00:49 Uhr schrieb Tim Parkhurst:

> So I'm thinking (dangerous, I know)...might it be easier to put 
> together a
> keyboard with photo interrupter type switches?

One could build a three-dimensional, or even four-dimensional keyboard 
switching matrix with these. Arrange the receivers in a usual 
two-dimensional matrix, but with several receivers in parallel. Only 
one of them at a time has the light source activated.

Might save some port pins.

Ingo