What's eCos
eCos is a free open source real-time operating system intended for embedded applications. The highly configurable nature of eCos allows the operating system to be customised to precise application requirements, delivering the best possible run-time performance and an optimised hardware resource footprint. With provided configuration tools (configtool and ecosconfig) it is possible to build configurations that scale from minimal that require less than 32KiB memory to reach full featured operating system with networking, file system, serial communication, etc.
eCos for Kinetis
Currently the Kinetis eCos support includes:
- UART;
- Ethernet - with TCP/IP through either lwIP or BSD stack;
- Flash - program and erase;
- eDMA library;
- DSPI - including MMC/SD card support;
- Real Time Clock.
- Cache;
- DDRAM;
- FlexBus;
Following features are available for testing:
Configuring eCos for Kinetis
Start the graphical configuration tool configtool, then from menu select Build->Templates. In Hardware selection box select your board:

In our case we select TWR-K70F120M.
Save the configuration and select Build->Library. configtool will build a customised eCos library and extract headers for you.
Now you are ready for your "Hello world".
Further reading
You shall find complete eCos documentation at eCos Documentation