The Superloop and Cooperative Scheduling
Every embedded program is an infinite loop. The interesting question is what is inside it. A while(1) that calls three functions in order is the simplest architecture that can run a device, it ships in an enormous number of products, and it is entirely capable of being the right answer for the lifetime of a project. It is also the architecture that fails most quietly when it stops being the right answer, because nothing breaks — the loop just gets slower, and one day a button press is dropped.