[sdiy] Rotary encoder

[Ingo Debus]

Am 10.01.2009 um 20:25 schrieb Cary Roberts:

>>> However, as 74C922 are pretty expensive ($7.50 even at Futurlec),
>>> it's probably
>>> not an ideal solution...
>>>
>>
>> Still a brilliant idea, IMHO.
>> It's also handy if one wants to interface a 12 position switch to a
>> microcontroller. 7 I/O ports versus 12.
>
> Excuse my ignorance, but how is this brilliant?  Using an obsolete
> expensive part in place of a microcontroller that costs less than a  
> 10th
> as much seems absurd.

Sorry, I should have worded this clearer.
What I thought was brilliant, is removing the stop of a 3*4 rotary  
switch thus making a 12-step switch where the 12 switches can be  
arranged in a matrix. If you want to interface a standard 1 * 12  
rotary switch to a microcontroller without additional circuitry you  
need 12 inputs. With the modified 3 * 4 switch you only need 7 I/Os.

Ingo