Temperature monitoring with DHT22 and LEDs

Smart temperature monitoring with EzloPi

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Temperature monitoring with DHT22 and LEDs

The EzloPi smart devices provide automation through simple, customizable use with our open-source EzloPi platform, making daily life easier and improving human-machine interactions.

Before moving into this example, it is very important to know about the device registration, provisioning and converting the ESP32 device into an EzloPi device along with knowledge of Web Flasher, MiOS Mobile Application for Android/iOS and the MiOS Web Application.

1. About this example

This project involves creating a temperature monitoring system using the DHT22 sensor and the EzloPi device. This project reads temperature data from the DHT22 sensor and controls two LEDs (green and red) based on the temperature levels. The green LED lights up when the temperature is within a safe range, indicating normal conditions, while the red LED activates if the temperature exceeds a predefined threshold, signaling a warning. This project setup provides a visual indication of environmental temperature changes, making it suitable for smart home monitoring, basic climate monitoring and safety applications.

2. Project Demonstration Video

Welcome to the project demonstration video section. The following video showcases the key aspects of Temperature monitoring with DHT22 and LEDs, providing a visual walkthrough of its implementation.

3. Circuit Diagram & Interface

The following components are required for interfacing with the EzloPi device:

ESP32 as an EzloPi smart device.
DHT22 temperature & humidity sensor.
Two LEDs
Two 100 Ohm Resistors.

The wiring diagram of ESP32 30 pin is represented as follows:

The following connections are made in order to complete the circuit setup.

From ESP32 to DHT22:

ESP32	DHT22
3V3	VCC
GND	GND
D15	Data-Signal

4. Interfacing the DHT22 and Two LEDs with EzloPi Web Flasher

1. Set up your device/hardware by visiting config.ezlopi.com

Now, click on the Connect Device button and a pop-up window will appear.

Now, select COM Port to which your ESP32 device is connected. In our case, the COM3 port is used.

Click Connect

If you are new to this and it's your first time configuring, select Create new Device ID. Enter Wifi SSID and Wifi Password.
In the Device Configuration, tab click on One Wire.

A One Wire window will open for inputting the following parameters:

Set a device name of your choosing. In our case, we set it to DHT22.
Set the GPIO to 15.
Set Device Subtype to DHT11 Temperature & Humidity Sensor.
Then Click Apply Button.

In the Device Configuration, tab click on Digital Output.

A Digital Output window will open for inputting the following parameters:

Set a device name of your choosing. In our case, we set it to Green LED.
Set Device Subtype to LED.
Set the OUT GPIO to 4.
Set the Resistor to PULL UP.
Then Click Apply Button.
After clicking the apply button you can see a table of your setting in the device configuration tab.
Press the Flash Device button.i>

Again, In the Device Configuration, tab click on Digital Output.

A Digital Output window will open for inputting the following parameters:

Set a device name of your choosing. In our case, we set it to Red LED.
Set Device Subtype to LED.
Set the OUT GPIO to 5.
Set the Resistor to PULL UP.
Then Click Apply Button.
After clicking the apply button you can see a table of your setting in the device configuration tab.
Press the Flash Device button.

A window will appear on the bottom right side of the screen displaying “Please press BOOT button while flashing begins.”

Hold the BOOT button down until the next window appears on the bottom right side of the screen which says “Installation prepared. Please release the boot button now.”

Release the BOOT button from your ESP32 when this pop-up on the bottom right window appears.

After some time, a popup will appear saying Device Flashed Successfully! This means that your device has been set up successfully.

5. MiOS Web Dashboard

After configuring the controller with the EzloPi web flasher, head to ezlogic.mios.com

Use the same credential to log in that you used for configuring the controller with the web flasher.

Now, on the MiOS web dashboard, you will see the tiles of your connected devices as shown above labeled as DHT22 (one for temperature and one for humidity) and Two LEDs (Green & Red LED).
Currently,DHT22 tiles show temperature and humidity while both LEDs are OFF.

MeshBots:

On the left side of the screen under Automation, click on MeshBots.
On meshbot screen, click on Create new MeshBot button present on the top right corner of the screen.
After clicking on Create new MeshBot, you will see this now under Automation MeshBot click on EzloPi.

On the next screen you will see that we can create a name of our choosing, in this case we write it as Test005.

In the trigger tab you can set the TRIGGER for your device and in the ACTION tab you can set the action to be performed based on the trigger which you have created.

Set these things in TRIGGER section:

Set Node Type to Device.
Set the Node to DHT22.
Set the Capability to current_temperature.
Set the variables to value.
Set the Comparator to Less(<).
Set the value type to value.
Set the Value to 40.

Set these values in the TRUE part of the ACTION section.

Set Node type to Device.
Set Controllable to Green LED.
Set Capability to switch.
Set value to true.
Add another Action in the TRUE part of the ACTION section.
Set Node type to Device.
Set Controllable to Red LED.
Set Capability to switch.
Set value to false.

Set these values in the FALSE part of the ACTION section.

Set Node type to Device.
Set Controllable to Green LED.
Set Capability to switch.
Set value to false.
Add another Action in the FALSE part of the ACTION section.
Set Node type to Device.
Set Controllable to Red LED.
Set Capability to switch.
Set value to true.
After clicking the apply button you can see a table of your setting in the Current configuration tab.

After clicking the save button you can see this screen on the top right corner of the screen.

Here you can see your saved MeshBot. Now click on Dashboard.

Now as seen above, it shows that when the temperature is below 40°C irrespective of the humidity, the green LED turns ON and the red LED remains OFF because of the rules we have set in the meshbot.

Now as seen above, it shows that when the temperature reaches above the 40°C threshold, the green LED turns OFF and the red LED turns ON to trigger a warning alert because of the rules we have set in the meshbot.

6. MiOS App

You can download the MIOS Android app from the Google Play Store and Apple App Store.

After downloading the app, proceed to install the application and open it.

Using the MIOS mobile application, create a new Ezlo Cloud account using the sign-up option. If you already have an account, you may proceed to log in.

After successfully logging in, you will be able to see the number of controllers connected such as a lamp, fan, or any other device in the MiOS app. Tap on any controller of your desired ID:

You will be able to see the status of your controller whether it is online or offline. Access the device dashboard, and tap the device. The following view of the dashboard will appear:

Now as seen above, it shows that when the temperature is below 40°C irrespective of the humidity, the green LED turns ON and the red LED remains OFF because of the rules we have set in the meshbot.

Now as seen above, it shows that when the temperature reaches above the 40°C threshold, the green LED turns OFF and the red LED turns ON to trigger a warning alert because of the rules we have set in the meshbot.