[sdiy] Digital encoders missing codes in many devices - why?

Mike Bryant mbryant at futurehorizons.com
Sat Aug 21 21:53:59 CEST 2021

Well not since the very beginning, but certainly early on

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of cheater cheater via Synth-diy
Sent: 21 August 2021 18:21
To: David Riley
Cc: synth-diy
Subject: Re: [sdiy] Digital encoders missing codes in many devices - why?

That would be a good initial theory, however, I believe that mouse wheels are fully optical, and have been since the very beginning.

On Sat, Aug 21, 2021 at 6:04 PM David Riley <fraveydank at gmail.com> wrote:
> On Aug 21, 2021, at 09:24, cheater cheater via Synth-diy <synth-diy at synth-diy.org> wrote:
> >
> > Hi all,
> > I've noticed a trend in consumer electronics where encoders 
> > sometimes miss codes. By this I mean I'll scroll to the next detent 
> > and the corresponding value does not change. Sometimes it's 
> > completely skipped. Sometimes, the phase of the code will flip: for 
> > example, if normally the next code is sent out when overcoming the 
> > separation between subsequent detents at the "peak" of the 
> > separator, instead it will be sent out when moving around inside a 
> > single detent, when moving past the middle of the "valley" of the 
> > detent. However, this only happens rarely. For example, with a 
> > Logitech mouse, it'll only happen once every few days. With the 
> > Eventide stomp box, I have to make several full turns with the 
> > encoder before something like this happens.
> >
> > It comes in all places. My most recent problematic device is an 
> > Eventide H9, but this also happens on scroll wheels in Logitech 
> > mice, on microwave ovens, etc.
> >
> > Why does this happen? Why is it so spread out? Is this a programming 
> > issue, or a mechanical issue related to the lifetime of the encoder?
> Having made these before at various different scales, I’d guess that it’s probably mechanical quadrature encoders using brushes to contact. If so, intermittent brush contact would do exactly that; a lot of decoders also don’t handle things like simultaneous transitions well.
> There’s a reason ball mice used optical encoders. They last practically forever. Most brushless DC motors and other servos also use optical encoders. For some military hardware I worked with (the carrier-side instrument landing system antenna motors), we used a magnetic encoder, which I’ve not seen elsewhere.
> Anyway, degrading contacts would be my guess. Either bent or dirty brushes. Does a hit of De-Ox-It help?
> - Dave

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