Well, these encoders are spec'd with <5mS chatter or bounce. I don't want to
process a change, then poll again, finding a change that really is the same
one with the contacts still not settled and bouncing between 0 and 1.
Therefore I tried a debounce delay after detecting a change, and after the
delay checking if the same change is still there. After all the feedback
from you all good people, I will now try to process after first sign of
change, then delay for next polling.

Jan Didden

----- Original Message -----
From: "Jeff DeMaagd" <jeff@DEMAAGD.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, July 22, 2001 7:39 PM
Subject: Re: [PIC]: Stumped by rotary encoder


> Is this a mechanical encoder?  Really long signal lines?  I don't
understand
> why you are having to deal with bounces.  The encoders I've used had clean
> outputs.
>
> Jeff
>
> ----- Original Message -----
> From: SkinTech <jan.didden@SKINTECH.BE>
>
>
> [sorry, send at first without tag. therefore resend]
>
> Hi all,
>
> I always try to solve my own problems (I learn from it) but this one has
me
> stumped.
> My project has a 16F74, reading the output of a rotary encoder (2 bit),
see
> below.
> First I check by polling if there is a change in the 'A' bit. If so, I
wait
> some 10mS (debounce) and then look again. If there is still a change, I
> check if it is 1>0 or 0>1. In each case, I then check the 'B' bit to
> determine direction. For debugging I beep once (CW) or twice (CCW) the
> buzzer.
> When turning the encoder I get seemingly random results. Sometimes it
beeps
> 3 times, or 4 times, or 1 time, or not at all over half a revolution. Then
> it starts again. I'm pretty sure it has to do with the debounce, but I
can't
> get it right. I must add that the beep adds another 10 or 30 mS delay
> between pollings.
> The encoders are spec'd at <5mS chatter.
>
> Has anyone experience with decoding rotary encoders? Any help or ideas
would
> be greatly appreciated.
>
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