STM32L4_L4+

page_type	description	languages	products
sample	Connecting STMicroelectronics B-L475E-IOT01A and B-L4S5I-IOT01A devices to Azure IoT using Azure RTOS	c	azure-iot azure-iot-pnp azure-rtos azure-iot-dps azure-iot-hub

Getting started with the STMicroelectronics B-L475E-IOT01A / B-L4S5I-IOTOA1 Discovery kits

Total completion time: 30 minutes

In this tutorial you use Azure RTOS to connect either the STMicroelectronics B-L475E-IOT01A or B-L4S5I-IOT01A Discovery kit (hereafter, the STM DevKit) to Azure IoT. The article is part of the series Getting started with Azure RTOS. The series introduces device developers to Azure RTOS, and shows how to connect several device evaluation kits to Azure IoT.

You will complete the following tasks:

• Install a set of embedded development tools for programming the STM DevKit in C
• Build an image and flash it onto the STM DevKit
• Use Azure IoT Central to create cloud components, view properties, view device telemetry, and call direct commands

Prerequisites

• A PC running Microsoft Windows 10

• Git for cloning the repository

• Hardware

  The * STM DevKit. The tutorial works with either of the following STM Discovery kits.

  • B-L475E-IOT01A
  • B-L4S5I-IOT01A
  • Wi-Fi 2.4 GHz
  • USB 2.0 A male to Micro USB male cable

Prepare the development environment

To set up your development environment, first you clone a GitHub repo that contains all the assets you need for the tutorial. Then you install a set of programming tools.

Clone the repo for the tutorial

Clone the following repo to download all sample device code, setup scripts, and offline versions of the documentation. If you previously cloned this repo in another tutorial, you don't need to do it again.

To clone the repo, run the following command:

git clone --recursive https://github.com/azure-rtos/getting-started.git

Install the tools

The cloned repo contains a setup script that installs and configures the required tools. If you installed these tools in another tutorial in the getting started guide, you don't need to do it again.

Note: The setup script installs the following tools:

• CMake: Build
• ARM GCC: Compile
• Termite: Monitor serial port output for connected devices

To install the tools:

1. From File Explorer, navigate to the following path in the repo and run the setup script named get-toolchain.bat:

   getting-started\tools\get-toolchain.bat

2. After the installation, open a new console window to recognize the configuration changes made by the setup script. Use this console to complete the remaining programming tasks in the tutorial. You can use Windows CMD, PowerShell, or Git Bash for Windows.

3. Run the following code to confirm that CMake version 3.14 or later is installed.

   cmake --version

Create the cloud components

Create the IoT Central Application

There are several ways to connect devices to Azure IoT. In this section, you learn how to connect a device by using Azure IoT Central. IoT Central is an IoT application platform that reduces the cost and complexity of creating and managing IoT solutions.

To create a new application:

1. From Azure IoT Central portal, select My apps on the side navigation menu.

2. Select + New application.

3. Select Custom apps.

4. Add Application Name and a URL.

5. Choose the Free Pricing plan to activate a 7-day trial.

   

6. Select Create.

7. After IoT Central provisions the application, it redirects you automatically to the new application dashboard.

   Note: If you have an existing IoT Central application, you can use it to complete the steps in this article rather than create a new application.

Create a new device

In this section, you use the IoT Central application dashboard to create a new device. You will use the connection information for the newly created device to securely connect your physical device in a later section.

To create a device:

1. From the application dashboard, select Devices on the side navigation menu.

2. Select + New to bring up the Create a new device window.

3. Leave Device template as Unassigned.

4. Fill in the desired Device name and Device ID.

   

5. Select the Create button.

6. The newly created device will appear in the All devices list. Select on the device name to show details.

7. Select Connect in the top right menu bar to display the connection information used to configure the device in the next section.

   

8. Note the connection values for the following connection string parameters displayed in Connect dialog. You'll add these values to a configuration file in the next step:

• ID scope
• Device ID
• Primary key

Prepare the device

To connect the STM DevKit to Azure, you'll modify a configuration file for Wi-Fi and Azure IoT settings, rebuild the image, and flash the image to the device.

Add configuration

1. Open the following file in a text editor:

   getting-started\STMicroelectronics\STM32L4_L4+\app\azure_config.h

2. Set the Wi-Fi constants to the following values from your local environment.

   Constant name	Value
   WIFI_SSID	{Your Wi-Fi ssid}
   WIFI_PASSWORD	{Your Wi-Fi password}
   WIFI_MODE	{One of the enumerated Wi-Fi mode values in the file}

3. Set the Azure IoT device information constants to the values that you saved after you created Azure resources.

   Constant name	Value
   IOT_DPS_ID_SCOPE	{Your ID scope value}
   IOT_DPS_REGISTRATION_ID	{Your Device ID value}
   IOT_DEVICE_SAS_KEY	{Your Primary key value}

4. Save and close the file.

Build the image

In your console or in File Explorer, run the script rebuild.bat at the following path to build the image:

getting-started\STMicroelectronics\STM32L4_L4+\tools\rebuild.bat

After the build completes, confirm that two binary files were created. There's a binary image for each of the STM Devkit. The build saves the images to the following paths:

getting-started\STMicroelectronics\STM32L4_L4+\build\app\stm32l475_azure_iot.bin

getting-started\STMicroelectronics\STM32L4_L4+\build\app\stm32l4S5_azure_iot.bin

Flash the image

1. On the STM DevKit MCU, locate the Reset button, the Micro USB port which is labeled USB STLink, and the board part number. You will refer to these items in the next steps. All of them are highlighted in the following picture:

   

2. Connect the Micro USB cable to the USB STLINK port on the STM DevKit, and then connect it to your computer.

   Note: For detailed setup information about the STM DevKit, see the instructions on the packaging, or see B-L475E-IOT01A Resources / B-L4S5I-IOT01A Resources.

3. In File Explorer, find the binary files that you created in the previous section.

4. Copy the binary file whose file name corresponds to the part number of the STM Devkit you are using. For example, if your board part number is B-L475E-IOT01A1, copy the binary file named stm32l475_azure_iot.bin.

5. 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_L4IOT.

6. Paste the binary file into the root folder of the STM Devkit. Flashing starts automatically and completes in a few seconds.

   Note: During the flashing process, a LED toggles between red and green on the STM DevKit.

Confirm device connection details

You can use the Termite utility to monitor communication and confirm that your device is set up correctly.

Note: If you are unable to connect Termite to your devkit, install the ST-LINK driver and try again. See Troubleshooting for additional steps.

1. Start Termite.

2. Select Settings.

3. In the Serial port settings dialog, check the following settings and update if needed:

   • Baud rate: 115,200
   • Port: The port that your STM DevKit is connected to. If there are multiple port options in the dropdown, you can find the correct port to use. Open Windows Device Manager, and view Ports to identify which port to use.

   

4. Select OK.

5. Press the Reset button on the device. The button is black and is labeled on the device.

6. In the Termite console, check the following checkpoint values to confirm that the device is initialized and connected to Azure IoT.

   Starting Azure thread
   
   Initializing WiFi
   	Connecting to SSID 'iot'
   SUCCESS: WiFi connected to iot
   
   Initializing DHCP
   	IP address: 10.0.0.123
   	Mask: 255.255.255.0
   	Gateway: 10.0.0.1
   SUCCESS: DHCP initialized
   
   Initializing DNS client
   	DNS address: 10.0.0.1
   SUCCESS: DNS client initialized
   
   Initializing SNTP client
   	SNTP server 0.pool.ntp.org
   	SNTP IP address: 185.242.56.3
   	SNTP time update: Nov 16, 2020 23:47:35.385 UTC 
   SUCCESS: SNTP initialized
   
   Initializing Azure IoT DPS client
   	DPS endpoint: global.azure-devices-provisioning.net
   	DPS ID scope: ***
   	Registration ID: ***
   SUCCESS: Azure IoT DPS client initialized
   
   Initializing Azure IoT Hub client
   	Hub hostname: ***
   	Device id: ***
   	Model id: dtmi:azurertos:devkit:gsg;1
   Connected to IoTHub
   SUCCESS: Azure IoT Hub client initialized
   
   Starting Main loop
   

   Important: If the DNS client initialization fails and notifies you that the Wi-Fi firmware is out of date, you'll need to update the Wi-Fi module firmware. Download and install the Inventek ISM 43362 Wi-Fi module firmware update. Then press the Reset button on the device to recheck your connection, and continue this tutorial.

Keep Termite open to monitor device output in the following steps.

Verify the device status

To view the device status in IoT Central portal:

1. From the application dashboard, select Devices on the side navigation menu.

2. Check the Device status of the device is updated to Provisioned.

3. Check the Device template of the device has updated to Getting Stared Guide.

   

View telemetry

With IoT Central, you can view the flow of telemetry from your device to the cloud.

To view telemetry in IoT Central portal:

1. From the application dashboard, select Devices on the side navigation menu.

2. Select the device from the device list.

3. View the telemetry as the device sends messages to the cloud in the Overview tab.

   

Note: You can also monitor telemetry from the device by using the Termite terminal.

Call a direct method on the device

You can also use IoT Central to call a direct method that you have implemented on your device. Direct methods have a name, and can optionally have a JSON payload, configurable connection, and method timeout. In this section, you call a method that enables you to turn an LED on or off.

To call a method in IoT Central portal:

1. Select Command tab from the device page.

2. Select State and select Run. The LED light should turn on.

   

3. Unselect State and select Run. The LED light should turn off.

View device information

You can view the device information from IoT Central.

Select About tab from the device page.

Debugging

For debugging the application, see Debugging with Visual Studio Code.

Clean up resources

If you no longer need the Azure resources created in this tutorial, you can delete them from the IoT Central portal. Optionally, if you continue to another tutorial in this Getting Started guide, you can keep the resources you've already created and reuse them.

To keep the Azure IoT Central sample application but remove only specific devices:

1. Select the Devices tab for your application.
2. Select the device from the device list.
3. Select Delete.

To remove the entire Azure IoT Central sample application and all its devices and resources:

1. Select Administration > Your application.
2. Select Delete.

Next Steps

In this tutorial you built a custom image that contains Azure RTOS sample code, and then flashed the image to the STM DevKit device. You also used the IoT Central portal to create Azure resources, connect the STM DevKit securely to Azure, view telemetry, and send messages.

• For device developers, the suggested next step is to see the other tutorials in the series Getting started with Azure RTOS.
• If you have issues getting your device to initialize or connect after following the steps in this guide, see Troubleshooting.
• To learn more about how Azure RTOS components are used in the sample code for this tutorial, see Using Azure RTOS in the Getting Started Guides.

  Note: Azure RTOS provides OEMs with components to secure communication and to create code and data isolation using underlying MCU/MPU hardware protection mechanisms. However, each OEM is ultimately responsible for ensuring that their device meets evolving security requirements.