Due to the widespread use of microcontroller unit (MCU) in application and education areas, there is a need for initialization code generation for MCUs to reduce developers’ effort and to aid beginners’ learning of MCU programming. A common realization for initialization code generation software is a graphical user interface (GUI) with all the available initialization settings for user selection, and the initialization code can be generated based on the user’s configuration. This has been achieved by several software using different implementations. This paper evaluates two current initialization code generation software to identify the existing problems and requirements. It then presents a methodology to describe MCU structure to support the software’s initialization code generation functionality to achieve flexibility and effectiveness. Our approach observes low development cost, enables user contribution to define and update MCU structure, and provides suitable guide for user to avoid faulty initialization settings.