Azure IoT Central example for esp32-azure-kit

In this tutorial, you will learn how to use the esp32-azure-kit board to send data to Azure IoT Central and to receive events back from Azure IoT Central to be processed by the board.

Features implemented

• Telemetry data sent for all onboard sensors
• LED status of network, Azure IoT send events
• Display temperature and humidity on screen
• Reported twin property dice number is sent when shaking the device (uses accelerometer sensor data)
• Cloud to device messages (supports sending a message to display on the screen, press button to go back humiture screen)
• Desired twin property to turn on a fan at a defined speed and temperature (Need to connect a L298N DC motor control)
• Direct twin method calls to turn on and off a fan (Need to connect a L298N DC motor control)

What you need

• An esp32-azure-board kit

  

• An active Azure subscription. If you do not have one, you can register via one of these two methods:

  • Activate a free 30-day trial Microsoft Azure account.
  • Claim your Azure credit if you are MSDN or Visual Studio subscriber.

Open the project folder

Start VS Code

• Start Visual Studio Code.
• Make sure Azure IoT Device Workbench is installed.
• Connect ESP32-azure-kit to your PC.

Open IoT Workbench Examples

• Use F1 or Ctrl+Shift+P (macOS: Cmd+Shift+P) to open the command palette, type Azure IoT Device Workbench, and then select Open Examples....

  

• Select ESP32 Arduino.

  

• Then the IoT Device Workbench Example window is shown up.

  

• Find ESP32 IoT Contral Sample and click Open Sample button. A new VS Code window with a project folder in it opens.

  

Create Azure IoT Central application

1. Use you Azure account log into Azure IoT Central.

2. Create a free custom applicaton.

   

3. Click Create Device Templates and enter a template name to create a new template

4. Click the Edit Template button, then click the New measurement button to add measurements

   

5. Create new Telemetry as below:

   Display Name	Field Name	Unit	Minimum Value	Maximum Value
   Temperature	Temperature	℃	-40	100
   Humidity	Humidity	%	0	100
   Light	AmbientLight	lx	0	3800
   Pressure	Pressure	kPa	26	126
   Altitude	Altitude	M
   MagnetometerX	MagnetometerX	mgauss
   MagnetometerY	MagnetometerY	mgauss
   MagnetometerZ	MagnetometerZ	mgauss
   Pitch	Pitch	°	-180	180
   Roll	Roll	°	-180	180

   Note: You can only add the measurements that you care about, you don't need to add all of them

6. Click Device Explorer -> + -> Real to add a real device. After creating the device, it will navigate to the device template page.

   

7. Click the Properties tab, then click Edit Tempalte. Select Device Property on the Liabray at the left of the page, then add the following properties

   Display Name	Field Name	Data Type
   Dice Number	dieNumber	number

8. Click the Commands tab, then click Edit Tempalte. Click New Command at the left of the page, then add the following properties

   Display Name	Field Name	Data Type
   Message	echo	text

   Click + at the right of Input Fields to add the following field

   Display Name	Field Name	Data Type
   Send message to device	displayedValue	text

9. Click the Settings tab, then click Edit Tempalte. Select Number on the Liabray at the left of th page, then add the following properties

   Display Name	Field Name	Unit	Minimum Value	Maximum Value	Initial Value
   Fan Speed	fanSpeed	%	10	100	50

   Click Save and repeat this step to add the follwing properties

   Display Name	Field Name	Unit	Minimum Value	Maximum Value	Initial Value
   Temperature Threshold	temThreshold	℃	-40	100	30

   Click the Commands tab again, then click Edit Tempalte. Click New Command at the left of the page, then add the following properties

   Display Name	Field Name	Data Type
   Start Fan	startFan	text
   Stop Fan	stopFan	text

   Note: This step requries a L298N DC motor control connect to the GPIO 12 and 13 on the esp32-azure-kit board, if you don't have the motor connected, you can skip this step

10. At last, click Connect button at the top right of the page, it will pop Device Conenction page. Download the dps-keygen tool at here based on your OS, use the dps_cstr tool to generate the connectoin string as below.

    

    dps_cstr <scope_id> <device_id> <Primary Key(for device)> 

    scope_id, device_id and Primary Key is listed on the Device Connectin page.

Config Device Code

1. Open the source file(.ino) for device code and update the following lines with your WiFi ssid and password:

   // Please input the SSID and password of WiFi
   const char* ssid     = "";
   const char* password = "";

2. Copy and paste the device connection string that generated on the previous step into the following line in device code.

   This copies the connection string that is retrieved from the Create Azure IoT Central application step.

   /*String containing Hostname, Device Id & Device Key in the format:                         */
   /*  "HostName=<host_name>;DeviceId=<device_id>;SharedAccessKey=<device_key>"                */
   /*  "HostName=<host_name>;DeviceId=<device_id>;SharedAccessSignature=<device_sas_token>"    */
   static const char* connectionString = "";

Build and upload the device code

1. Open the command palette and select Azure IoT Device Workbench: Upload Device Code.

   

2. VS Code then starts verifying and uploading the code to your DevKit.

   

3. The ESP32 device reboots and starts running the code.

   Note: M5Stack-Core-ESP32 is set as the default board after the IoT project is created. To change the setting, use F1 or Ctrl+Shift+P (macOS: Cmd+Shift+P) to open the command palette, type and select Arduino: Board Config. Change to use ESP32 Wrover Module (esp32) board in the Arduino Board Configuration window.

   

Monitor device status in Azure IoT Central

1. Use you Azure account log into Azure IoT Central

2. Once the device is connected to WIFI, the WIFI LED will be turned on. Once the device connect and send data to Azure IoT Central, the Azure LED will blink while sending data. The device's defalut screen will show the temperature and humidity.

   

3. Navigate to the device measurements page, you'll see all the telemetry data from the device

   

4. Navigate to the device Commands page, write a message at the Message grid and click Run, the message will display on the device screen.

   

   Note: Click the KEY_IO0 button on the device will switch the messaage screen to humiture screen

5. Shake the device, it will simulate shaking a dice and report a random dice number to IoT central, you can see the dice number at the IoT Central Properties page

   

6. This step requries a L298N DC motor control connect to the GPIO 12 and 13 on the esp32-azure-kit board. Once you have the motor control connect with a fan and the board, navigate to the Commands page, you can use the Start Fan and Stop Fan command to control the motor on and off.

   

   Navigate to the settings page, you can set the fan speed and temperature threshold, once the temperature is greate than the defined value, the fan will start automaticlly at the speed.