Worked on the zephyrproject-rtos/zephyr-testing repository to enhance the reliability of USB CDC ACM serial communication in embedded systems. Focused on addressing data loss during the CDC ACM enable sequence by implementing a fix that ensures the TX FIFO is always drained when the interface is activated, even if the UART API is not used. This approach reduced startup data loss risks and improved data transmission consistency across various device configurations. The work involved C programming, USB subsystem debugging, and kernel patching, demonstrating attention to detail in embedded systems development and a methodical approach to code review and commit documentation.