This is well known in IoT field I assume, I used it a few years back, after comparing with tinyos and such. Basically you have Linux, then FreeRTOS, then Contik

This is well known in IoT field I assume, I used it a few years back, after comparing with tinyos and such. Basically you have Linux, then FreeRTOS, then Contiki, from large system to the tiny devices.