I actually tried to realize a volume control with a alps rotary encoder (EC11E15204A3) and the rotary encoder feature of Sigma Studio.
Unfortunately it didn't work.
I connected it like on this app note on page 3, figure 3: http://www.analog.com/media/en/technical-documentation/application-notes/AN-951.pdf
GPIO8 and 9 were used in sigma studio, both were configured as GPIO Input with debounce (I also tried without debounce).
Is it possible with this rotary encoder?
To solve my problem on a quick way I used a regular potentiometer and controled the volume with a ADC. This was working quite perfectly. But in my final design I would prefer a rotary encoder.
Thanks a lot in advance.
Greetings from Germany.