LUFA ships with several basic pre-made board drivers, to control hardware present on the supported board hardware - such as Dataflash ICs, LEDs, Joysticks, or other hardware peripherals. When compiling an application which makes use of one or more board drivers located in LUFA/Drivers/Board, you must also indicate what board hardware you are using in your project makefile. This is done by defining the BOARD macro using the -D switch passed to the compiler, with a constant of BOARD_{Name}. For example -DBOARD=BOARD_USBKEY instructs the compiler to use the USBKEY board hardware drivers.

If your application does not use *any* board level drivers, you can omit the definition of the BOARD macro. However, some users may wish to write their own custom board hardware drivers which are to remain compatible with the LUFA hardware API. To do this, the BOARD macro should be defined to the value BOARD_USER. This indicates that the board level drivers should be located in a folder named "Board" located inside the application's folder.

When used, the driver stub files located in the LUFA/CodeTemplates/DriverStubs folder should be copied to the user Board/ directory, and fleshed out to include the values and code needed to control the custom board hardware. Once done, the existing LUFA board level APIs (accessed in the regular LUFA/Drivers/Board/ folder) will redirect to the user board drivers, maintaining code compatibility and allowing for a different board to be selected through the project makefile with no code changes.