Core Code Embedded
Core Code Embedded Operating System is a full featured all layer embedded operating system for the STM32F4XX range of Microcontrollers. It includes an RTOS. It is available for purchase under usage license.
Using the OS allows you to massively reduce the development cost of your project, greatle reduce the development time, and greatly derisk the development. The price points for embedded development are being driven down. Usage of the OS allows this issue to be addressed.