In this article, we delve into the common I/O port errors encountered when working with the C8051F321-GMR microcontroller and how to troubleshoot and resolve them effectively. With the growing popularity of the C8051F321-GMR in embedded systems, understanding and resolving I/O port issues is critical for efficient and reliable microcontroller operation. This solution manual will provide you with detailed strategies, practical examples, and best practices for debugging and fixing I/O port-related problems.