µC/OS-III
Introduced in 2009 and available as open-source, µC/OS-III offers all of the features and functions of µC/OS-II. The biggest difference is the number of supported tasks. µC/OS-III allows any number of application tasks, priority levels, and tasks per level.
The full documentation is available online at left.
In addition to the full documentation at left, hardware-specific µC/OS-III books are also available for download in PDF format: