This project uses an ESP32 and DHT11 sensor to measure temperature and humidity. The data is sent to a Mosquitto broker and visualized on a Node-RED dashboard. It's an improvement over this simpler project, which only works on a local network with no dashboard. Have a look at the old one to see the differences.

It's an assignment for the course "Internet of Things" at the Instituto Politécnico de Portalegre, in Portugal.

You can find out more about the course here.

You can find more screenshots here.

• ESP32
• DHT11 Temperature and Humidity Sensor
• 10k Ohm resistor
• Breadboard
• Jumper wires

• PlatformIO (preferred) or Arduino IDE
• Mosquitto MQTT Broker
• Node-RED

There is a more detailed guide here.

1. Hardware Setup: Connect the DHT11 sensor to your ESP32. The connections are as follows:

   • DHT11 VCC to ESP32 3V3
   • DHT11 GND to ESP32 GND
   • DHT11 DATA to ESP32 GPIO 4
   • DHT11 DATA to 10k Ohm resistor
   • 10k Ohm resistor to ESP32 3V3

   It should look something like this:

2. Software Setup:

   • Install and setup VSCode + PlatformIO (preferred) or Arduino IDE.
   • Install Mosquitto MQTT Broker.
   • Install Node-RED.
   • Install Node-RED Dashboard.

3. Code Deployment: Upload the provided code to your ESP32.

1. Start the Mosquitto broker.
2. Start Node-RED and open the provided dashboard.
3. Power on the ESP32.

Download and install the Mosquitto MQTT Broker from here. You can start the broker with the default configuration by running mosquitto in the terminal.

Download and install Node-RED from here. You can start Node-RED by running node-red in the terminal.

It's very easy to create a flow in Node-RED. You can find more information about it here.

Install the Node-RED Dashboard from here. You can access the dashboard by going to http://localhost:1880/ui in your browser.

Be sure to follow the hardware setup correctly. If you're using a different ESP32 board, the GPIO pins may be different.

Pay attention to the serial output of the ESP32. It's very useful for debugging.

In the mosquitto.conf file, be sure to set the allow_anonymous option to true. Also set listener to 1883 0.0.0.0 as seen below.

• The code has comments explaining what each line does.
• The DHT11 sensor is a very cheap sensor. It's not very accurate and it's not very reliable. It's a good sensor to start with, but it's not recommended for real-world applications.
• It's very easy to install everything if you are running Linux. If you are running Windows, you may have some problems. I recommend using Fedora.
• VSCode + PlatformIO is preferred over the Arduino IDE. It's much easier to use and it has a lot of features, such as code completion, code linting, git integration, etc.
• The ESP32 is a very powerful microcontroller. It's very easy to use and it has a lot of features. It's a good choice for this project.
• Note that the arduino uno showed in the picture is not used in this project. The only microcontroller on is the ESP32.

• Connect another ESP32 with a DHT11 sensor to the same MQTT broker and display the data on the same dashboard.
• Subscribe multiple devices to the same MQTT broker so they can do actions based on the data received.
• Get a Raspberry Pi and install the Mosquitto MQTT Broker and Node-RED on it. This way you can have a dedicated device for this project.
• Use a good sensor instead of a cheap DHT11 sensor.
• Implement a better way to handle errors.
• Utilize these sensors in a real-world scenario, like a smart home. For example, turn on the air conditioner when the temperature is too high, or turn on the humidifier when the humidity is too low.