JaeOS® -- Just Another Embedded OS
Because the RTOS should be a commodity.
This is a port of the RTOS to run on the ARM M3/M4 microcontrollers.
The port was done on the STM32 microcontroler using various versions of the Nucleo demo board.
It should be generic enough to run on other similar microcontrollers although some adjustments may be needed for library calls to talk to on chip peripherals such as serial ports.