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

Jay Schwichtenberg jschwich53 at comcast.net
Sun Feb 9 00:17:33 CET 2020


Shawn,

Thanks put I understand encoders and have all sorts of code for 
encoders. Embedded HW/SW stuff was my day job for a number of years.

Thanks
Jay S.

On 2/8/2020 3:04 PM, Shawn Rakestraw wrote:
> I don't know if this will help you or not, but I have just assembled 
> two projects that use Teensy microcontrollers. This is the encoder 
> that I used. I can't say for sure how it outputs the signals.
>
> https://www.mouser.com/ProductDetail/858-EN11-HSM1BF20
>
> Shawn
>
> On Sat, Feb 8, 2020 at 5:44 PM Jay Schwichtenberg 
> <jschwich53 at comcast.net <mailto:jschwich53 at comcast.net>> wrote:
>
>     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.
>
>     https://www.mouser.com/datasheet/2/15/alps_alps-s-a0008379064-1-1733314.pdf
>
>     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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