[sdiy] Logic for rotary encoders

[Leif]

Haven't thought of it really, but it will be an expensive way to go, since 
I have to buy devel cards for the altera chip then... I know basice verilog 
and vhdl programming, but a lot has to be learned as well... Since what me 
and to other students here are building involves a lot of dsp programming 
and microcontroller programming, we hoped that some logic could do the 
trick... but I suppose that an altera chip is a better solution.... Have to 
find out pricing for the devel boards then..

thanks,
Leif

At 16:44 20.01.2003 -0700, you wrote:
>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
> >
> >
> >