FreeRTOS

🛠 Technology Stack Languages: Embedded C (C11) Operating System: FreeRTOS (POSIX Port) Protocols: I2C, Hardware Interrupts (GPIO) Tools: libgpiod, GDB, GCC, Linux terminal The Project Overview The objective was to design a robust, thread-safe sensor acquisition system on a Linux-based RTOS environment. This project demonstrates high-reliability multitasking where multiple sensors share a single communication bus without data corruption or timing jitter. Technical Highlights Kernel-Level Multitasking: Leveraged the FreeRTOS POSIX Port to manage three concurrent tasks using fixed-priority preemption, ensuring mission-critical tasks always receive CPU time. Thread-Safe I2C Management: Implemented a Mutex Semaphore to arbitrate access to the I2C bus. This prevents data collisions between the ADXL345 Accelerometer and DS3231 RTC tasks when accessing shared hardware. Asynchronous Event Handling: Developed a high-priority hardware listener using libgpiod to capture falling-edge interrupts on GPIO 17, triggering a system-wide graceful shutdown. Deterministic Scheduling: Replaced standard sleep calls with vTaskDelayUntil() to ensure a consistent 10Hz sampling frequency, eliminating timing drift critical for real-time telemetry analysis. Resource Cleanup: Engineered a custom shutdown() sequence ensuring all RTOS tasks are deleted and Linux file descriptors (I2C/GPIO) are properly closed before process termination. Live RTOS Execution & Task Arbitration The following terminal trace captures the live execution of the FreeRTOS tasks. It demonstrates the real-time arbitration of the I2C bus between the high-frequency accelerometer and the low-frequency real-time clock. ...