ESP32 TFT LCD 240x240 Tutorial-Display Images & DHT11 Sensor

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In this comprehensive tutorial, you will learn how to build a real-time temperature and humidity monitoring dashboard using an ESP32, a 240×240 TFT LCD display (ST7789), and a DHT11 sensor. The project demonstrates how to display text, icons, and live sensor data on a colorful TFT screen.

This guide is designed for makers, students, and engineers who want to improve their skills in embedded systems, IoT development, and ESP32 graphical interfaces.

📺 Video Tutorial – Full Walkthrough

This article complements the full step-by-step video tutorial below. In the video, you will see the complete wiring, TFT initialization, bitmap generation, and a live demo of temperature and humidity updates on the screen.

📌 Tip: Watching the video first will make the wiring and code much easier to follow.

🧰 Components Required

  • ESP32 Development Board [Image of ESP32 development board pinout]
  • 240×240 TFT LCD (ST7789 Driver)
  • DHT11 Temperature & Humidity Sensor
  • Breadboard
  • Jumper Wires

🖥️ Understanding the ST7789 TFT LCD

The ST7789 is a popular TFT display controller widely used in ESP32 projects. It communicates via SPI, which allows fast data transfer and smooth graphics rendering.

Key advantages of the ST7789 display include:

  • High resolution (240×240 pixels)
  • Excellent color depth
  • Low power consumption
  • Strong library support (Adafruit)

In this project, the TFT is used to display icons, text, and live sensor readings with clear visual separation and color coding.

🔌 ESP32 to TFT LCD (ST7789) Wiring

The TFT LCD uses SPI communication. Make sure the display operates at 3.3V to avoid damaging the ESP32 or the screen.

LCD Pin ESP32 Pin Function
GND GND Ground
VCC 3.3V Power Supply
SCL GPIO18 SPI Clock (SCLK)
SDA GPIO23 SPI Data (MOSI)
RES GPIO15 Reset
DC GPIO2 Data / Command Select
BLK GND Backlight (Always ON)

Connecting the BLK pin to GND keeps the backlight permanently ON. If brightness control is required, this pin can be connected to a PWM-capable GPIO.

🌡️ ESP32 to DHT11 Sensor Wiring

The DHT11 sensor communicates using a single-wire digital protocol. It does not use SPI or I2C.

DHT11 Pin ESP32 Pin Function
VCC 3.3V Power Supply
GND GND Ground
DATA GPIO4 Digital Data Signal

If your DHT11 module does not include an onboard pull-up resistor, add a 10kΩ resistor between VCC and DATA.

🖼️ Displaying Images on the TFT Screen

To display icons such as temperature and humidity symbols, images must be converted into bitmap arrays that the ESP32 can render.

Use the following online tool to convert images:

🔗 https://javl.github.io/image2cpp/

Recommended Conversion Settings

  • Resolution: 64×64 pixels
  • Color format: Monochrome
  • Output format: Arduino code

The generated arrays are stored in flash memory using PROGMEM, which saves valuable RAM on the ESP32.

📂 Source Code Repository

The complete source code used in this project is available on GitHub:

🔗 https://github.com/iotstation/esp32_DHT11_IPS240x240

🧠 How the Code Works

The project uses the Adafruit_GFX and Adafruit_ST7789 libraries to control the TFT display. The DHT library is used to read temperature and humidity values.

During each loop cycle:

  • Temperature and humidity are read from the DHT11
  • Invalid sensor values are checked
  • The TFT screen is cleared
  • Icons are drawn using drawBitmap()
  • Live values are printed below each icon

The screen refresh interval is set to 8 seconds to ensure stable readings and avoid flickering.

⚠️ Common Issues & Troubleshooting

  • Blank screen: Check SPI pins and display voltage
  • Wrong colors: Verify display driver (ST7789)
  • DHT11 returns NaN: Check wiring and pull-up resistor
  • Flickering text: Ensure screen is cleared before redrawing

🚀 Project Extensions & Ideas

  • Replace DHT11 with DHT22 for higher accuracy
  • Add Wi-Fi and MQTT support
  • Send data to InfluxDB or a cloud dashboard
  • Add touch interaction
  • Implement deep sleep for power saving

✅ Conclusion

This ESP32 TFT LCD project demonstrates how to combine sensors, graphics, and microcontrollers to build a professional-looking embedded dashboard. It is a solid foundation for more advanced IoT and smart display applications.

If you found this tutorial helpful, don’t forget to watch the video, check out the GitHub repository, and subscribe for more ESP32 and IoT content.

Happy coding! 🚀

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