[sdiy] Question how to improve rotary encoder feel

[Jay Schwichtenberg]

You are correct Brian. Looked at the product line that I used and they have
phase, straight 4 bit and gray code.

Jay

-----Original Message-----
From: rsdio at audiobanshee.com [mailto:rsdio at audiobanshee.com] 
Sent: Friday, June 09, 2017 5:43 PM
To: Jay Schwichtenberg
Cc: 'synth-diy mailing list'
Subject: Re: [sdiy] Question how to improve rotary encoder feel

That sounds expensive, Jay, assuming you're correct that they use a Hamming
code. That's because Hamming codes would require more mechanical switches
than output bits, and price seems to increase geometrically with mechanical
additions.

Are you sure these numeric encoders aren't simply using Gray codes? Gray
codes are more efficient because the number of mechanical switches match the
number of output bits. There is always at least one Gray code for any bit
count that only requires a single bit (switch) change per code transition.
Given the cost of the mechanical switches, I assume that all mechanical
numeric encoders use Gray codes. If someone has a data sheet for a contrary
example, I'd be very interested to see it.

A big disadvantage of actually using a Hamming code for a rotary encoder is
that it requires three bit changes per code transition. Due to the nature of
imperfect mechanical constructions, those three bits would not all change at
the same time, rendering the encoder very prone to error. I don't see how
Hamming can have any advantage over Gray for mechanical encoders.

Brian


On Jun 9, 2017, at 3:53 PM, Jay Schwichtenberg <jschwich53 at comcast.net>
wrote:
> But one thing to think about is that they also make encoders that have
> numeric values, usually some form of hamming code that can be used for
> absolute position.
>