> > I have an embedded computer which has four user
> > readable DIP switches on it. Board is running
> > at 3.3 volts. I want to be able to distinguish
> > between 7 possible SPST switches being closed
> > (one at a time) or all being open. I thought
>
> If those SPST switches could become 2 and 3 pole switches, the problem is
> trivial to solve....
Unfortunately, not possible.
> > "OK. I'll just convert the single switch event
> > to a binary number by hooking it to the appropriate
> > pins on the DIP switch. Then I'll prevent the
> > multi-bit numbers from cross feeding the single
> > bit events by putting diodes in." But, the diodes
> > have too much resistance for the board to see the
> > switch as closed. The single-bit switches, 1, 2
> > and 4, read just fine.
>
> The current involved is presumably small, so the problem is the 0.7V
> forward drop of the silicon diodes.
>
> You might try using germanium (if you can find them) or shottky diodes.
> They should have a lower forward voltage drop.
Thanks!
Received on Tue Feb 22 2000 - 17:35:51 GMT
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