Worked on the apache/nuttx repository to enhance USART stability and interrupt reliability for the GD32F4 platform, focusing on low-level firmware development in C. Addressed a critical boot-time issue by introducing null checks in the arm_earlyserialinit routine, preventing HardFaults when USART is not enabled. Improved interrupt handling by explicitly managing CTL selector bits in up_disableusartint, ensuring RX interrupts remain functional after syslog or putc operations. Demonstrated strong embedded systems skills through rigorous hardware register manipulation and defensive programming. Validated these changes on the mplant-gd32f450 board, resulting in more robust serial console operation and reliable system startup across configurations.