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About Real Time Engineers ltd.

"Provide a free product that surpasses the quality and
service demanded by users of commercial alternatives"

FreeRTOS is solely owned, run, developed and maintained by Real Time Engineers Ltd.

Real Time Engineers Ltd. have been working in close partnership with the world's leading chip companies for more than 12 years to provide you award winning, commercial grade, and completely free high quality software that is free from any IP infringement risk.

Corporate and product summary presentation

About FreeRTOS

[Also see the "What is an RTOS?" and "Why use an RTOS" pages]

FreeRTOSTM is a market leading RTOS from Real Time Engineers Ltd. that supports 35 architectures and received >113000 downloads during 2014. It is professionally developed, strictly quality controlled, robust, supported, and free to embed in commercial products without any requirement to expose your proprietary source code.

FreeRTOS has become the de facto standard RTOS for microcontrollers by removing common objections to using free software, and in so doing, providing a truly compelling free software model.

Implementation Quality Management

Value Proposition
High quality C source code under strict configuration management
Safety critical version ensures dependability
Cross platform support secures time investment
Tutorial books and training to educate engineers
Pre-configured example projects for all supported ports
Free support, quoted as better than some commercial alternatives
Large and growing user base and community
Peace of mind - low cost commercial options can be taken at any time
= A low total cost of ownership, risk free, & compelling solution

RTOS Technology Highlights
Pre-emptive scheduling option Easy to use message passing
Co-operative scheduling option Round robin with time slicing
Fast task notifications Mutexes with priority inheritance
6K to 12K ROM footprint Recursive mutexes
Configurable / scalable Binary and counting semaphores
Chip and compiler agnostic Very efficient software timers
Some ports never completely disable interrupts Easy to use API

  • ARM connected community RTOS partner
  • Xilinx Microblaze and Zynq partner
  • Renesas Gold Alliance Partner RTOS partner
  • Partner of NXP supplying RTOS to all ARM microcontrollers
  • Silicon Labs low power RTOS partner
  • Microchip premier third party partner
  • Texas Instruments MCU Developer Network for RTOS on ARM and MSP430 microcontrollers
  • Freescale Alliance Member supplying RTOS for ARM Kinetis and ColdFire microcontroller
  • Infineon XMC ARM Cortex Microcontrollers
  • Atmel RTOS partner for SAM3 ARM Cortex Microcontrollers and AVR32
  • Cypress RTOS supplier for ARM Cortex-M3
  • STmicroelectronics RTOS partner for STM32 ARM Cortex microcontrollers
  • Fujitsu RTOS partner for Cortex-M3 and FM3 microcontrollers
  • Microsemi RTOS partner for ARM Cortex-M3 embedded processors
  • Atollic RTOS partner for all real time embedded systems
  • IAR Embedded Workbench RTOS partner for all real time embedded systems
  • ARM Keil RTOS partner for real time embedded systems
  • Embedded Artists RTOS partner for ARM based microcontroller embedded hardware
FreeRTOS is very strictly quality managed, not just in software coding standards and look and feel, but also in implementation. For example:
  • FreeRTOS never performs a non-deterministic operation, such as walking a linked list, from inside a critical section or interrupt.

  • We are particularly proud of the efficient software timer implementation that does not use any CPU time unless a timer actually needs servicing. Software timers do not contain variables that need to be counted down to zero.

  • Likewise, lists of Blocked (pended) tasks do not require time consuming periodic servicing.

  • Direct to task notifications allow fast task signalling, with practically no RAM overhead, and can be used in the majority of inter-task and interrupt to task signalling scenarios.

  • The FreeRTOS queue usage model manages to combine simplicity with flexibility (in a tiny code size) - attributes that are normally mutually exclusive.

  • FreeRTOS queues are base primitives on top of which other communication and synchronisation primitives are built. The code re-use obtained dramatically reduced overall code size, which in turn assists testing and helps ensure robustness.

In addition, the TÜV SÜD certified SIL 3 SafeRTOS real time kernel was originally derived from FreeRTOS, and has undergone the most stringent analysis and test process - the results of which were fed back into the FreeRTOS code base (when commonality still existed).


"Provide a free product that surpasses the quality and service
demanded by users of commercial alternatives"

The original mission of the FreeRTOS project was to provide a free RTOS solution that was easy to use. That is, easy to build and deploy, on a Windows (or Linux) host computer, without having to figure out which source files are required, which include paths are required, or how to configure the real time debugging environment. This has been achieved through the provision of pre-configured, build-able, example projects for each officially support port.

Naturally, as the FreeRTOS started circa 2003, how these projects are created has evolved for the better, and some original projects remain that don't demonstrate all of the RTOS functionality, or have become stale. However, each project is fully tested before it is added to the FreeRTOS zip file distribution, and many RTOS demo projects undergo active maintenance before each new release. Responding to user feedback, each new demo added to the distribution now also includes a simple "blinky" style getting started configuration to compliment the comprehensive examples.

Design Goals

The primary design goals are:
  • Easy to use
  • Small footprint
  • Robust

FreeRTOS Founder

The FreeRTOS project was founded by Richard Barry. Richard graduated with 1st Class Honours in Computing for Real Time Systems. He's been directly involved in the start up of several companies, primarily working in the industrial automation and aerospace and simulation markets. Richard is currently a director of Real Time Engineers Ltd., owners and maintainers of the FreeRTOS project.

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Copyright (C) 2004-2010 Richard Barry. Copyright (C) 2010-2016 Real Time Engineers Ltd.
Any and all data, files, source code, html content and documentation included in the FreeRTOSTM distribution or available on this site are the exclusive property of Real Time Engineers Ltd.. See the files license.txt (included in the distribution) and this copyright notice for more information. FreeRTOSTM and FreeRTOS.orgTM are trade marks of Real Time Engineers Ltd.

Latest News:

FreeRTOS V9.0.0 is now available for download.

Free TCP/IP and file system demos for the RTOS

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FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Renesas Electronics Gold Alliance RTOS Partner.jpg

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers

Atmel RTOS partner supporting ARM Cortex-M3 and AVR32 microcontrollers

STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Xilinx Microblaze and Zynq partner

Silicon Labs low power RTOS partner

Altera RTOS partner for Nios II and Cortex-A9 SoC

Freescale Alliance RTOS Member supporting ARM and ColdFire microcontrollers

Infineon ARM Cortex-M microcontrollers

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

Cypress RTOS partner supporting ARM Cortex-M3

Fujitsu RTOS partner supporting ARM Cortex-M3 and FM3

Microsemi (previously Actel) RTOS partner supporting ARM Cortex-M3

Atollic Partner

IAR Partner

Keil ARM Partner

Embedded Artists

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