What are the best resources for learning about RTOS

1) The best way to learn is to implement a RTOS. A good place to start is http://www.freertos.org/

Here's a brief overview on RTOS for those that aren't looking to commit to a book or code just yet. [Credit to Professor Jim Peckol at UW, this answer is based on my old notes from his class]

An operating system has to provide 3 essential things:

1. Task Scheduling - The scheduler determines which task to run and when a task will run
2. Task Dispatching - The dispatcher handles the necessary operations to get a task ready to go
3. Intertask Communication - This is the mechanism that handles how you exchange data and information between tasks and processes on the same machine or from other machines

These 3 essential things are what makes up the smallest portion of an OS called the Kernel.

A real time operating system is just a special purpose operating system. The 'real time' part of the name does not mean that the system responds quickly, it just means that there are rigid time requirements that must be met. If these time requirements are not met, your results can become inaccurate or unreliable.

So you want to use a RTOS when you need to monitor and control physical  processes in a timely manner. The constraints you have deal with when using RTOS are tight scheduling, predictability, and robustness.

There are two kinds of RTOS:

1. Hard Real Time - System delays are known or at least bounded. Said to be operating correctly if the system can return results within any time constraints.
2. Soft Real Time - Critical tasks get priority over other tasks and will retain priority until the task is completed. This is another way of saying that real time tasks cannot be kept waiting indefinitely. Soft real time makes it easier  to mix the system with other systems.

The other functions that the OS handles outside of the Kernel are:

• Process management
• Memory management
• I/O system management
• File system management
• System protection
• Networking
• Command interruption 

2) Jean Labrosse's MicroC/OS-II: The Real-Time Kernel book.  It covers basic RTOS concepts and includes well documented source code.  The operating system is also simple enough that you can pretty much understand the whole thing.

http://www.amazon.com/MicroC-OS-...

Avoid his most recent book, uC/OS-III as it no longer includes the source code and is really just documentation for his commercial OS.

3)You can read RTOS by Qing li for Begineers otherwise Market leading RTOS (Real Time Operating System) for embedded systems with Internet of Things extensions is good option to learn rtos


4)this is for RENESAS RTOS related PDF

 see this link for downloading:: https://www.renesas.com/en-in/doc/products/tool/apn/res05b0008_r8cap.pdf