[sdiy] Question how to improve rotary encoder feel

[rsdio at audiobanshee.com]

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.
>