Or.
Do a little research and play your encoders without using interrupts.
As much fun and utility they can be, interrupts can be tricky and very often can be programmed without. I invented my own encoder, then I discovered almost exactly the same thing in a nice library.
They basic trick is to give your encoders some regular attention by calling a service routine from your main loop.
can do either. Other advantages accrue as he points out. I had some crummy rotary encoders that def benefited from the denouncing.
Save interrupts for when you just can't not.
a7