[sdiy] Question how to improve rotary encoder feel

[Eric Brombaugh]

I've done something very similar to what Scott describes below. You can 
find high-resolution optical shaft encoders that are used for mechanical 
sensing at reasonable prices on ebay:

http://www.ebay.com/itm/Rotary-Encoder-400P-R-6mm-Incremental-Optical-Shaft-Working-Measurement-5-24V-ED-/131969802647

Similar to the dsPIC processors Scott mentioned, STM32 processors have a 
special mode on their timer peripherals that can decode and count the 
2-phase signals from such encoders. By enabling counts on all edges you 
can get 4x the PPR resolution, so the example 400ppr encoder above 
yields 1600 counts/revolution. I've used that as a frequency control on 
digital radios - it's extremely smooth and provides very natural 
acceleration. The downside of course is that it's mechanically cumbersome.

Eric

On 06/09/2017 06:07 AM, Scott Gravenhorst wrote:
>
> Just spit-ballin' here...
>
> There are optical encoders that are used to detect motor speed and/or
> shaft angular position.  Obviously, these are designed to be connected
> mechanically to a motor, but I see no reason a person with mechanical
> skills couldn't adapt one to use with a knob.  They have no detents, so
> they rotate freely and smoothly, even to the point of being able to
> spin.  Maybe a flywheel could be added to allow more spinning with a
> given amount of force.  I've no idea what these would cost tho, nor the
> resolution of counts per revolution.  The only reason I know about
> these is from reading about them in a dsPIC...MC (motor control) chip
> datasheet.  These chips have QEI peripherals in them to automatically
> count the revolutions.
>
> -- ScottG
> ________________________________________________________________________
> -- Scott Gravenhorst
> -- http://scott.joviansynth.com/
> -- When the going gets tough, the tough use the command line.
> -- Matt 21:22
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