FreeRTOS - Portable Open-Source Mini RT Kernel
Scaleable real time kernel designed specifically for small embedded systems. FreeRTOS is truly free, even for use in commercial applications. The FreeRTOS license does not pose any risk to your proprietary software.
Real Time Application Design Tutorial
The application will execute on an embedded single board computer that must control a plant while maintaining both local and remote user interfaces.

STM32 Connectivity Line ARM Cortex-M3 demo Including a uIP Embedded Web Server Example.
Features Include
- Free RTOS kernel - preemptive, cooperative and hybrid configuration options.
- The SafeRTOS derivative product provides a high level of confidence in the code integrity.
- Official support for 23 architectures (counting ARM7 and ARM Cortex M3 as one architecture each).
- FreeRTOS-MPU supports the Cortex M3 Memory Protection Unit (MPU).
- Designed to be small, simple and easy to use.
- Free development tools (Cortex-M3, ARM7, MSP430, H8/S, AMD, AVR, x86 and 8051 ports).