[simpits-tech] rotary encoder

[Gene Buckle]

> I've seen a lot of rotary encoder stuff in the group, and until
> recently, I didn't understand what the fuss was all about.  With recent
> dialogue, I do - as far as what key combo is sent depending on which way
> the knob was turned.
>
> This was something I always intended to take care of with some sort of
> simple rotary switch and my EPIC.  Say you have a rotary with 10
> contacts.  That's 10 separate connections to the EPIC, and in the EPIC
> program, all one would need to do is set up some fairly straightforward
> logic to analyze where the rotary is at.  If the program simply stored
> the value associated with the current position of the knob, and when a
> different contact of the 10 was detected, it would be compared to the
> previously stored value, which would determine which way the knob was
> being turned.  This would give EPIC enought data to send whatever the
> appropriate key combination was for increment or decrement.
>
> Is there a flaw in this thinking?


Steve, rotary encoders are infinite devices.  There are no stops.  You can
turn it left forever and it won't stop you until it wears out.  These are
used for things like tuning radios where the display is totally digital.

A rotary encoder is not the device you want to use if the target
application only has n positions.  For that, you'd use a rotary _switch_
like your 10 pole example above.  (Rotary switches count their contacts as
"poles".  A 5 position switch would thus be called a 5 pole rotary.)

Another thing to consider with rotary switches is the physical operation.
There are two types - make before break and break before make.  The make
before break types will engage the common pole to the desired pole before
contact with the prior position is broken.  For example, hold down your
"A" key, then while holding down the "A" key, hold down the "G" key and
while holding down the "G" key, release the "A" key.  That's make before
break.  Break before make works the same way, but you use the same finger
on key "G" ad you did on A", thus you break the connection at the "A" key
before making it on the "G".

For our applications, the break before make type are the ones you want.

g.