One thing that wasn’t disclosed in any of your previous post is that your
timer_fnc() actually is a non-static class method.
That’s why it is important to work on your code not mine
For non-static class functions you need to use another
And in order to actually do that you need an object instance of your
For that reason you cannot have this in your library:
Timer timer(1000, MotionService::timer_fnc); - not even with the correct constructor as you haven’t got an object at that time.
The way you laid out your library I’d rather have the
Timer as a private member of the class and construct and start it in the class constructor.