KleOS
KleOS brings together Arduino, FreeRTOS and Arduino-mk to you.
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* Arduino-mk. The tool to compile your Arduino projects from the command line.
Arduino is the opposite to real time; however, so many real world applications need to react to internal and external events in real time, e.g. as fast as possible, even seizing the CPU from the code that is currently executing. FreeRTOS is the glorious tool behind getting such behaviour.
And as you become an Arduino power user you find the IDE too clumsy, so why don't you compile your way (e.g. in the terminal) using your preferred source code editor? ...