What is FreeRTOS?

Developed in partnership with the world's leading chip companies over a 15-year period, and now downloaded every 175 seconds, FreeRTOS is a market-leading real-time operating system (RTOS) for microcontrollers and small microprocessors. Distributed freely under the MIT open source license, FreeRTOS includes a kernel and a growing set of libraries suitable for use across all industry sectors. FreeRTOS is built with an emphasis on reliability and ease of use.

FreeRTOS includes libraries for connectivity, security, and over-the-air (OTA) updates. FreeRTOS also includes demo applications that show FreeRTOS features on qualified boards.

FreeRTOS is an open-source project. You can download the source code, contribute changes or enhancements, or report issues on the GitHub site at https://github.com/aws/amazon-freertos. We release FreeRTOS code under the MIT open source license, so you can use it in commercial and personal projects.

We also welcome contributions to the FreeRTOS documentation (FreeRTOS User Guide, FreeRTOS Porting Guide, and FreeRTOS Qualification Guide). The markdown source for the documentation is available at https://github.com/awsdocs/aws-freertos-docs. It is released under the Creative Commons (CC BY-ND) license.

Downloading FreeRTOS source code

You can clone or download FreeRTOS from GitHub. See the README.md file for instructions.

FreeRTOS versioning

The FreeRTOS kernel and components are released individually and use semantic versioning. Integrated FreeRTOS releases are made periodically. All releases use date-based versioning with the format YYYYMM.NN, where:

For example, a second release in July 2021 would be 202107.01.

Previously, FreeRTOS releases used semantic versioning for major releases. Although it has moved to date-based versioning (FreeRTOS 1.4.8 updated to FreeRTOS AWS Reference Integrations 201906.00), the FreeRTOS kernel and each individual FreeRTOS library still retain semantic versioning. In semantic versioning, the version number itself (X.Y.Z) indicates whether the release is a major, minor, or point release. You can use the semantic version of a library to assess the scope and impact of a new release on your application.

LTS releases are maintained differently than other release types. Major and minor releases are frequently updated with new features in addition to defect resolutions. LTS releases are only updated with changes to address critical defects and security vulnerabilities. No new features are introduced in a given LTS release after launch. They are maintained for at least three calendar years after release, and provide device manufacturers the option to use a stable baseline as opposed to a more dynamic baseline represented by major and minor releases.

FreeRTOS architecture

FreeRTOS is typically flashed to devices as a single compiled image with all of the components required for device applications. This image combines functionality for the applications written by the embedded developer, the software libraries provided by Amazon, the FreeRTOS kernel, and drivers and board support packages (BSPs) for the hardware platform. Independent of the individual microcontroller being used, embedded application developers can expect the same standardized interfaces to the FreeRTOS kernel and all FreeRTOS software libraries.

FreeRTOS-qualified hardware platforms

The following hardware platforms are qualified for FreeRTOS:

Qualified devices are also listed on the AWS Partner Device Catalog.

For information about qualifying a new device, see the FreeRTOS Qualification Guide.

Development workflow

You start development by downloading FreeRTOS. You unzip the package and import it into your IDE. You can then develop an application on your selected hardware platform and manufacture and deploy these devices using the development process appropriate for your device. Deployed devices can connect to the AWS IoT service or AWS IoT Greengrass as part of a complete IoT solution.

Additional resources

These resources might be helpful to you.