Here's a brief summary:
- FreeRTOS: Uses software timers and a widely-used API, with a large community.
- ChibiOS: Offers a lightweight, flexible approach with hybrid scheduling.
- CooCox CoOS: Provides a simple API and low power consumption.
- Zephyr RTOS: Features a modern, modular architecture with efficient resource usage.
- Apache Mynewt OS: Offers a modular, extensible design with a small footprint.
Consider your project's specific needs when choosing an RTOS.