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

Mike Bryant mbryant at futurehorizons.com
Sat Aug 21 15:29:13 CEST 2021

This is usually down to the Chinese contract manufacturing house replacing quality Alps or Bourns encoders with cheaper crappy ones.  They'll claim the ones you specified were temporarily unavailable if challenged.

Increasing the current through the encoder will fix the problem for a while, but they simply don't last as long.

-----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 14:22
To: synth-diy
Subject: [sdiy] Digital encoders missing codes in many devices - why?

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?

Does such behavior indicate that the encoder is a bad production or even starting to die, or is it normal (or even acceptable) for those encoders to do that every now and then? Are there encoders that guaranteed don't ever do that?

Does anything have to be done on the microcontroller to stop this from happening? Beyond that necessary minimum, what else can be done?

It's really interesting to me that such a common input scheme has these issues, even at a company like Logitech who specializes in high-quality input devices - and the mice I noticed this on are fully new, highest-line of their products, sometimes several of them in a row after exchanging (due to other defects).

So what's up with that? Why is it so common?
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