The article discusses the evolution of CubeSats from educational tools to versatile platforms for real missions. It emphasizes the importance of developing a robust general embedded system model to facilitate adaptable satellite designs for various applications. Thus, this work aims to present a system architecture structure to achieve this goal through the implementation of seven main systems - the Energy Power System, On-Board Data Handling, Attitude and Orbit Control System, Telemetry, Tracking, and Command, Thermal Control System, Structural Design, and Payload System -, as a partial result of the development of the Tupã CubeSat, a 2U academic satellite designed to collect lightning data using computational vision. Furthermore, this work intends to contribute to the discussion about CubeSats as educational tools, providing resources to students implementing high-level projects ready for real-world application.