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

cheater cheater cheater00social at gmail.com
Sat Aug 21 19:20:56 CEST 2021

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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