[sdiy] Selecting a rotary encoder, transistions per detent?

Jay Schwichtenberg jschwich53 at comcast.net
Sat Feb 8 23:42:29 CET 2020

At least for the Alps pg 267 in the data sheet on the Mouser web site 
show you what's going on. This is pretty standard for this type of encoder.


Jay S.

On 2/7/2020 5:00 AM, Spiros Makris wrote:
> Hello,
> I am putting together a teensy application that uses rotary encoders. 
> I picked up two different ones from my local shops, but they seem to 
> have a different output waveform scheme.
> One is an EC11e15204a3 alps (according to the guy selling it) and on 
> each detent, the outputs switch between high and low. So, 00->11->00 
> and each transition from 00 to 11 and vice versa happens when you hit 
> a detent.
> The other is a bourns by the looks of it, and works differently: When 
> resting, it defaults to 00. When turned, it briefly becomes 1, then 
> returns to 00.
> (obviously, the turn direction is detected during the transitions).
> The second type detects two increments instead of one, as a result.
> Where in the datasheet is this specified? Both are sold as "2 channel 
> quadrature outputs" but the detection code is slightly different 
> (unless I'm missing something?). Is there code that can work with 
> both? I am using polling and shift registers and don't need any 
> significant accuracy- the delay so far feels great.
> Is there a cheaper alternative to the 5pin arrangement of the EC11? It 
> seems that those without switches only have 3 pins- they will be going 
> on a prefboard and the extra support would be welcome (I'm not 
> compelled to drill 64 holes for the side supports :P ).
> Regards,
> Spiros
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