I'm getting really stuck on basic program structure in embassy. 

The examples create everything in the main function, but is there a nice way to abstract the board specific stuff into a board file, and all the init stuff into a init function?

Or is the Hal way of `static BUTTON: Mutex<RefCell<Option<Type>>> = ...` the only way to do it?

Are there any good examples of larger projects?

Sorry for the beginner questions, any help would be much appreciated!