Worked on the telink-semi/zephyr repository, focusing on embedded systems and Bluetooth functionality using C and RTOS. Addressed a critical issue affecting BLE initialization by correcting the definition of the ctr_lock mutex in the random_ctr_drbg.c module. This change ensured that the sysworkq task properly acquired the mutex during Bluetooth initialization, restoring reliable BLE operation. The work required a detailed understanding of concurrency and synchronization within the Zephyr RTOS environment. Although no new features were added during this period, the targeted bug fix improved system stability and Bluetooth reliability, demonstrating a methodical approach to resolving low-level embedded software issues.