Embedded developers always use their favorite controllers, and if you want to modify open source code, you often have to dive deep in the datasheet of that controller. The "Embedded Firmware Library" is a project which offers a kind of API to control the controller-functions and the functions of the peripheral units on a certain board. As an application developer, you don't have to know anything about the registers of the controller. And you can write controller- and board-independent code...