Can I use one external interrupt to call different functions?

[PerryBebbington]

Those are the same signals as you get from a rotary encoder. There are libraries for encoders, find one and use it. There are also lots of topics in the forum about them, do some searching.

While it doesn't solve your problem you might find this helpful:

Reading rotary encoders as a state machine

I and others have occasionally commented in replies to questions that there is no need to debounce a rotary encoder if they are read using a state based approach. However, this has never, so far as I aware, ever been explained properly. This tutorial provides that explanation along with sample code to demonstrate the principle. However, while the code works there are shortcomings that would need to be overcome in order to use the code or something like it in a project. The code below has been …