FreeRTOS

FreeRTOS is a real-time operating system for microcontrollers. It is designed for small, resource-constrained devices and provides a scalable, preemptive, real-time kernel for microcontrollers.

It is open source, royalty-free, and supports a wide range of microcontroller architectures. FreeRTOS provides a simple, small, and easy-to-use API for creating real-time applications.