FIT consists of a Board Support Package (BSP), peripheral function modules, middleware modules, and interface modules. On the lowest layer, the Board Support Package performs the initial MCU settings, clock settings, and pin settings. This can be configured with graphical tools, showing the customer e.g. the clock tree with the different settings to be selected or the package view with all functions of each pin to be selectable. There are peripheral modules for all RX peripherals with the most common functions used. On the higher layer there are FIT modules for middleware, like TCP/IP for Ethernet communication. All layers can be accessed by API, and of course the register level for time critical thread as well. On the application level, there is an RX common Application Program Interface (API), enabling an easy migration of the application from one RX device to a new one.