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PRTOS is an open-source preemptive real time operating system kernel for embedded applications. It presently supports the AVR and MSP430 architectures.
The advantages of PRTOS are:
It has the smallest footprint of any true preemptive system: 1.9kB for basic scheduling and task control, 5.1kB with all the features below (AVR '328 / gcc -Os);
Only 950 lines of code implement all of the RTOS features (SLOC-L);
The system is well documented with a comprehensive manual, well-commented source code, and a test suite demonstrating the features;
The system is proven - it has been in use since 1982 with applications in in-vitro medical equipment, process control instrumentation and industrial machinery;
PRTOS is released by Cleveland Engineering Design, LLC - developer of the CoRTOS cooperative RTOS
https://sourceforge.net/projects/cortos-simple/ and the CTREE analysis tool https://sourceforge.net/projects/ctree-graphic-tree-generator/
Commercial licensing is available
Features
- Preemptive and round-robin scheduling
- Signaling from task to task and ISR to task
- Delay and timeout functions
- Periodic signals
- Messaging and priority messaging
- Mutexes with priority inversion mitigation and FIFO or priority queuing
- Semaphores - binary, signaling and counting
