According to UBM embedded market study for 2015, Micrium µC/OS real-time operating system only came second after FreeRTOS when the company asked close to 1,000 engineers and managers around the world which operating systems they were currently using in their embedded products. The OS appears to be particularly popular in Asia, and the results are all the more impressive considering it’s a commercial operating systems.
But Micrium decided to bring more people on board by announcing a free version called µC/OS for Makers targeting hobbyists and startups (<$100k revenues) in February earlier this year. The real-time operating system includes a preemptive multitasking real-time kernel with optional round robin scheduling, has a low footprint (6K to 24K bytes code space, 1K+ bytes data space), support various types of targets including ARM Cortex-M and Cortex-A based MCU and processors such as STMicro STM32, NXP Kinetis, Cypress PSoC5, etc.., as well as Atmel AVR, TI MSP430 and many others.
The Maker version of the OS excludes the CAN module, Building Blocks and the Graphical UI library, but comes with USB, TCP/IP, Modbus, and file system stacks. A summary of the different licenses for µC/OS-III is shown in the table below.