The Internet of Things on AWS – Official Blog

Building microcontroller-based IoT applications using HTTPS client in Amazon FreeRTOS

Today, AWS announced general availability for HTTPS client support in Amazon FreeRTOS. Now you can use the HTTP/HTTPS protocol to connect your microcontroller-based IoT devices to AWS IoT Core and download files to those devices.

You might want to use HTTPS on your IoT devices running Amazon FreeRTOS for a variety of reasons:

  • To download new features, images, and security patches to your home appliances
  • To add music files to your library
  • To conform to existing HTTPS-based legacy systems
  • For higher-bandwidth downloads

With this release, you can download firmware files, assets, and images using HTTPS.

In this post, we discuss how to use HTTPS client support in Amazon FreeRTOS to support your IoT fleet. We explain how the HTTPS client library works, and provide links to source code and demos to get started.

HTTPS client library

The HTTPS client library in Amazon FreeRTOS supports the HTTP 1.1 protocol with HTTP GET requests. The library supports both synchronous and asynchronous programming models. The protocol blocks applications using a synchronous programming model of the HTTP client library from running instructions until the current HTTP request runs. The protocol allows applications using an asynchronous programming model of the HTTP client library to run instructions on the calling thread while the HTTP request runs on a different thread.

You can store these files on Amazon S3 or any other hosted service and specify the URL from which files download. You can transfer files in pieces and specify the size of each payload piece. Store your AWS access secret key outside your IoT device, on a secure Sigv4 presigned URL that you create. Your file transfers securely using TLS 1.2.

Getting started

Download source code containing the HTTPS client library from the Amazon FreeRTOS GitHub repository or the Amazon FreeRTOS console. The console gives you the flexibility to download only the libraries that you need for your application and development board. The download contains demos to help you to get started quickly.


In this post, we discussed how HTTPS client support in Amazon FreeRTOS supports your IoT fleet. We explained how the HTTPS client library works and how to get started. To learn more, visit Amazon FreeRTOS and check out the Amazon FreeRTOS User Guide.

As always, AWS welcomes feedback. Please submit comments or questions below.