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1  Products / Arduino Due / Re: Free RTOS on: March 05, 2013, 02:12:54 pm
From the Atmel Studio menu:

File->New->Example Project From ASF

In the dialogue box that opens:

1) On the left, select the kit.  Various SAM3 and SAM4 kits have FreeRTOS demo, the drivers that are demonstrated depends on the kits.
2) For example, expand Arduino Due (which is at the top of the list of kits).
3) In the list of projects you will see "FreeRTOS Peripheral Control Example" - selecting that will create the project (I have not tried it on the Arduino hardware and am not sure which interfaces it will demonstrate).
4) Read the instructions at the top of the file that contains the definition of main() - the examples use FreeRTOS+CLI which is free for use on Atmel microcontrollers.

If you create a project for the SAM4S or SAM3X EKs then you will see most (all) of the drivers demonstrated.

Richard (FreeRTOS)
2  Development / Other Software Development / Re: New FreeRTOS and ChibiOS/RT real time operating system libraries on: December 20, 2012, 04:07:01 am
Excellent :o)  I would be grateful if you could post a link (to the FreeRTOS part) in the FreeRTOS Interactive site.  Here is a link to the Atmel specific forum:

...or do you think I should create an Arduino specific forum?

There is also a demo that uses Atmel Studio 6 with GCC in the latest Atmel Software Framework (ASF) distribution (

Richard (
3  Products / Arduino Due / Re: Free RTOS on: November 23, 2012, 06:36:07 am
There is now a FreeRTOS project for the Arduino Due in the latest Atmel Software Framework (ASF) release, available through the Atmel Gallery

Richard (FreeRTOS)
4  Products / Arduino Due / Re: Free RTOS on: November 12, 2012, 04:05:19 pm
FreeRTOS is already running on the Due. I will post references within days.

5  Development / Other Software Development / Re: Try FreeRTOS - compare with ChibiOS/RT on: November 13, 2011, 09:47:57 am
I won't pretend to have read this thread other than skimming what is on this page - I just saw it was there from a Google alert, so my comments might not be that relevant.

To comment on context switch times though.  It is often quoted as the be all and end all, but in reality, you can make it as fast or slow as you like, within the limits of the hardware.  To get it really fast, just remove all the functionality (stack checking, tracing, interrupt nesting, etc.) and use a bitmap scheduler (at the cost of usability).  Alternatively, write it all in assembly code, making it harder and longer to port, and harder to test.

The Cortex-M takes a certain time to save/restore its registers.  This is done mainly in hardware, on interrupt entry, so has nothing to do with the RTOS.  What is left of the context can be saved in just one or two asm instructions, which again, are fixed execution time.  When people measure context save times, generally they measure different things on different systems, and compare apples with guava, thinking they are comparing apples with apples.

I never claim FreeRTOS to be the fastest, but one of the cleanest, smallest, best supported, etc. etec.


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