> -----Original Message-----
> From: Simon-Thijs de Feber [SMTP:stdf23173@YAHOO.CO.UK]
> Sent: Thursday, January 04, 2001 1:44 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      [EE]: Rotary Encoder
>
> Hello All,
>
>
> i'd like to connect a rotary encoder to a 16F84.
> I know i can use the RB4-7 inputs (interrupt on
> change), but my bournce rotary encoder has different
> behaviour than expected.
>
> Between 2 dents (clicks) it goes through the following
> bit pattern :
>
> Output A 0 1 1 0 0
> Output B 0 0 1 1 0
>
> where in the A= 0 and B= 0 are the in rest positions.
>
> Is my pic at 10MHZ hast enough to capture this
> pattern, count and put some I2C on other pins ???
>
> How do i capture the pattern anyway (without
> disturbance/bounce and etc) ????
>
>
> best regards,
>
> Simon
>
This is know as a quadrature decoder.  There have been hundreds if not
thousands of posts on this topic on the piclist, so a search of the archives
would be good idea.  Then get yourself to
http://www.piclist.com/techref/microchip/qenc.htm

There are several ways you can decode this type of controller, either
through polling or via external interupts.  A 10MHz PIC will easily be able
to poll a quadrature decoder with plenty of time left over if this decoder
is being turned by hand.  If this is on the output of e.g. a motor (unlikely
if it has dentents) you obviously need to poll the switch more quickly in
order to avoid lost states.

Regards

Mike

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