AZURE IOT FOR MIDDLEWARE

Question

Hello Experts,

I am looking to implement Azure IoT Middleware for FreeRTOS on my STM32F series board. I have reviewed the GitHub repositories related to Azure IoT Middleware, but I couldn't find clear information or step-by-step instructions.

Could you please guide me with a detailed procedure to set it up on my STM32F platform?

Thank you in advance for your support.

Best regards, Rakesh

Answer 1

Hi ,

Thanks for reaching out to Microsoft Q&A.

1. Overview

Azure IoT Middleware for FreeRTOS enables STM32 (and other MCUs) to securely connect to Azure IoT Hub or DPS using FreeRTOS. This is achieved by integrating:

• Azure IoT SDK

FreeRTOS

Azure IoT Middleware

Device SDKs (TLS, MQTT, etc.)

ST’s STM32Cube HAL

---

1. Prerequisites

Hardware

STM32F4 or STM32F7 series board (e.g., Nucleo-F429ZI)

ST-LINK debugger

Ethernet/WiFi (depending on connectivity)

Software

STM32CubeMX

STM32CubeIDE

Azure IoT Middleware for FreeRTOS repo

FreeRTOS repo

Azure SDK for C

STM32Cube MCU Package for your device (e.g., STM32CubeF4)

---

1. Step-by-Step Setup

Step 1: Create FreeRTOS + LWIP Project

Open STM32CubeMX.

Create a new project for your STM32F board.

Enable:

FreeRTOS middleware

LWIP TCP/IP stack (Ethernet)

Generate code and open in STM32CubeIDE.

Step 2: Add Azure IoT Middleware

Clone the following repos:

https://github.com/Azure/azure-sdk-for-c

https://github.com/azure-rtos/azure-iot-middleware-freertos

https://github.com/FreeRTOS/FreeRTOS

Copy required folders into your CubeIDE project:

Azure SDK for C: sdk/src/

Middleware: middleware/azure-iot

FreeRTOS and portable: freertos/FreeRTOS-Kernel

Add these to your include paths and source files.

Step 3: Integrate TLS and MQTT

You will need:

mbedTLS (included in STM32CubeMX with LWIP)

Port MQTT and TLS layers to STM32 HAL using examples from Azure Middleware repo.

Configure:

Platform abstraction (e.g., time, memory, logging)

tlsio_mbedtls.c (or implement tlsio_stm32.c)

Use mqtt_client from Azure SDK

Step 4: Connect to Azure IoT Hub

Use IoT Hub Device Connection String (or DPS if needed).

Implement sample connection logic from:

demos/

Example flow:

Initialize FreeRTOS

----->

Initialize MQTT

----->

Use Azure SDK to:

      ----->

      Format telemetry messages

           ----->

            Send data to IoT Hub

Step 5: Run and Debug

Flash firmware using ST-LINK

Monitor serial console output (UART)

Validate connection in Azure IoT Hub (Device twin, telemetry)

Reference Examples

STMicroelectronics Azure SDK Pack

ST provides a reference pack:

https://github.com/STMicroelectronics/STM32CubeExpansion_Azure

Includes:

Azure middleware

Sample for STM32L4/Nucleo boards

Integration with CubeMX and IDE

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Answer 2

Hi Amara Rakesh

Trying to summarize the steps mentioned here for STM32 boards

https://github.com/Azure-Samples/iot-middleware-freertos-samples/tree/main/demos/projects/ST/stm32h745i-disco/cm7

Prerequisites:

• ST Microelectronics DevKit: STM32H745I
• Ethernet Cable
• Micro USB male cable
• CMake (Version 3.13 or higher)
• Ninja build system (Version 1.10 or higher)
• GNU Arm Embedded Toolchain (This sample was tested against Version 10.3)
• Serial terminal tool like Termite, Putty, Tera Term, etc.
• ST Microelectronics DevKit: STM32H745I
• Ethernet Cable
• Micro USB male cable
• Prerequisites
• CMake (Version 3.13 or higher)
• Ninja build system (Version 1.10 or higher)
• GNU Arm Embedded Toolchain (This sample was tested against Version 10.3)
• Serial terminal tool like Termite, Putty, Tera Term, etc.

Setup Steps

1. Enable longpath support for Windows and Git

      git config --system core.longpaths true
   

2. Clone and initialize the Repository:

       git clone https://github.com/Azure-Samples/iot-middleware-freertos-samples.git
       git submodule update --init --recursive
      
   

3. Configure Azure IoT Hub:
   • Create an IoT Hub and register your device.
   • Use the Azure CLI or UI to retrieve connection strings from Azure IOT hub or use DPS (Device Provisioning Service).
4. Update Configuration Files: Update the file **iot-middleware-freertos-samples/demos/projects/ST/stm32h745i-disco/cm7/config/demo_config.h** with your device credentials (IoT Hub connection string/primary key or DPS info). Prepare the device
5. Build the image: navigate to the iot-middleware-freertos-samples directory and run the following commands:

      cmake -G Ninja -DVENDOR=ST -DBOARD=stm32h745i-disco -Bstm32h745i-disco .
      cmake --build stm32h745i-disco
      
      
   

   After the build completes, confirm that a folder named stm32h745i-disco/ was created and it contains a file named demo/projects/ST/stm32h745i-disco/iot-middleware-sample.bin.
6. Flash the Firmware:
   1. Connect the Micro USB cable to the USB STLINK port on the STM DevKit, and then connect it to your computer.
   2. In File Explorer, find the binary file that you created in the previous section and copy it.
   3. In File Explorer, find the STM Devkit that's connected to your computer. The device appears as a drive on your system with the drive label DIS_H745XI.
   4. Paste the binary file into the root folder of the STM Devkit. Flashing starts automatically and completes in a few seconds.
   5. Connect an Ethernet cable to your STM DevKit and your network equipment.
7. Monitor Output:
   • You can use one of the terminal applications to monitor communication and confirm that your device is set up correctly.
   • Go to Device Manager in Windows to determine which COM port your device was assigned. The following settings can be used to monitor serial data:
   • Baud Rate: 115200
   • Data Bits: 8
   • Stop Bits: 1
   • Parity: none
   • Flow Control: none
   • The device should connect to Azure IoT Hub and start sending telemetry.

Hope it provides more clarity. Please let us know if it helps

Thank you