ESP32 Climate Controller With SHT40 Sensor (Smart Temperature Control Project)

In this project we will build a smart climate controller using an ESP32 and an SHT40 temperature and humidity sensor.

This system monitors the surrounding temperature and automatically controls heating or cooling devices based on a user-defined target temperature.

Unlike simple temperature monitors, this controller includes:

1. Real-time environmental sensing
2. OLED display feedback
3. RGB status indication
4. Relay control for external devices
5. A WiFi web interface for setting the target temperature

This type of system can be used in greenhouses, indoor labs, server rooms, or smart home climate control setups.

If you want the full technical breakdown and theory behind this project, you can read the detailed article here:

https://matrixonelectronics.com/esp32-climate-controller-with-sht40-sensor/

You will need the following components for this project:

• ESP32 development board

• SHT40 temperature & humidity sensor

• 0.96" I2C OLED display (SSD1306)

• 1-channel relay module

• WS2812 RGB LED (or NeoPixel)

• Jumper wires

• Breadboard

• Optional: heater / fan for testing

The ESP32 acts as the main controller, while the SHT40 sensor provides highly accurate environmental readings.

The climate controller continuously monitors the environment and compares the current temperature with the target temperature set by the user.

Based on the difference between these values, the system decides whether to activate heating or remain idle.

The system states are:

• Idle Mode – when no target temperature is set

• Heating Mode – when temperature falls below the target

• Cooling / Standby Mode – when temperature exceeds the target

To avoid constant switching, a ±0.5°C tolerance window is used.

SHT40 Sensor

VCC → 3.3V

GND → GND

SDA → GPIO21

SCL → GPIO22

OLED Display

VCC → 3.3V

GND → GND

SDA → GPIO21

SCL → GPIO22

Relay Module

IN → GPIO5

VCC → 5V

GND → GND

WS2812 RGB LED

DIN → GPIO18

VCC → 5V

GND → GND

The I2C bus allows both the OLED display and SHT40 sensor to share the same SDA and SCL pins.

View Code on: https://matrixonelectronics.com/esp32-climate-controller-with-sht40-sensor/

Upload the project code to the ESP32 using the Arduino IDE.

Required libraries include:

1. Adafruit SHT4x
2. Adafruit SSD1306
3. Adafruit GFX
4. FastLED
5. ESPAsyncWebServer

Once uploaded, the ESP32 will automatically create a WiFi access point.

After powering the device:

1. Connect your phone or computer to the ESP32 WiFi network
2. Open a browser and go to : 192.168.4.1

The web dashboard will display:

• Current temperature

• Current humidity

• Target temperature input field

You can set the desired temperature directly from this interface.

The RGB LED provides visual feedback about the system state.

Green → Idle mode

Orange → Heating active

Cyan → Temperature above target

This makes it easy to check the system status without opening the dashboard.

You can test the system in a few simple ways.

• Warm the sensor with your hand

• Place it near a fan

• Adjust the target temperature through the web interface

The relay should activate when the temperature drops below the configured target.

This project can be used in many practical situations:

• Smart greenhouse temperature control

• Server room monitoring

• Indoor climate automation

• Smart home heating systems

• IoT environmental monitoring projects

This project demonstrates how an ESP32 microcontroller can be used to build a smart climate control system with sensing, automation, and web connectivity.

It combines several important embedded system concepts including:

1. Sensor interfacing
2. WiFi communication
3. relay control
4. real-time monitoring

For a deeper technical explanation, diagrams, and full documentation, you can check the full project article here:

https://matrixonelectronics.com/esp32-climate-controller-with-sht40-sensor/