StateOS
Free real-time operating system (RTOS) for microcontrollers
StateOS is a compact, open-source real-time operating system designed for embedded systems and written in ANSI C. It supports cooperative and preemptive multitasking, making it ideal for running multiple real-time tasks on microcontrollers. StateOS emphasizes clarity and ease of integration with existing projects and provides a full set of synchronization primitives, timers, and message-passing tools.