[sdiy] Logic for rotary encoders

[The Proteus]

Leif,

	Why not just use a small to medium size CPLD? Altera's EPM3032 or
3064 ($2-$3US in piece quantities iirc) should do the trick. Just have a
byte-wide port to read from your main CPU, then all of the encoder lines
can be selected directly from the CPLD. The logic can multiplex the
various encoders, and detect when the encoder changes value if you put
enough into it.

Regards,

Prot

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On Tue, 21 Jan 2003, Leif wrote:

> Hi
> 
> I have a microcontroller that is going to do some midi and control a dsp...
> 
> I've been looking into putting some controllers, rotary encoders... 40 of 
> them to be exact... + some switches as well.
> 
> I know that I can do groups of 16 and 16 encoders, and then use 74hc165 * 4 
> (8 bit parallel to serial shift registers) per group of 16 to do a 
> conversion of the data from 16 parallel inputs to a serial data 
> stream...  but for 40 controllers we would get 12 chips... which is a lot.
> 
> I only have a 8 bit port to use for the controllers, so I find the shift 
> register thing ok, but not very good... Anyone know a better way to do it ?
> 
> I might of course use a small microcontroller just to take care of the 
> counting and data, then send it to the first, but that is a expensive design..
> 
> cheers,
> Leif
> 
> 
>