LCD I2C Interface & DHT11 Sensor

Introduction

In this tutorial, we will interface a 16×2 LCD with I2C module and DHT11 sensor with ESP32.

The ESP32 will read temperature and humidity values from DHT11 sensor and display them on LCD.

Required Components

Component	Quantity
ESP32 Board	1
16×2 LCD with I2C Module	1
DHT11 Sensor	1
Breadboard	1
Jumper Wires	Few

DHT11 Sensor

DHT11 is a temperature and humidity sensor.

• Measures temperature in °C
• Measures humidity in %
• Simple digital output

LCD I2C Module

I2C module reduces LCD wiring using only 2 communication pins.

LCD I2C Pin	ESP32 Connection
VCC	5V
GND	GND
SDA	GPIO 21
SCL	GPIO 22

DHT11 Connection

DHT11 Pin	ESP32 Connection
VCC	3.3V
GND	GND
DATA	GPIO 4

Install Required Libraries

Install the following libraries from Arduino IDE Library Manager:

• DHT Sensor Library
• LiquidCrystal I2C
• Adafruit Unified Sensor

Open:

Sketch > Include Library > Manage Libraries

ESP32 LCD + DHT11 Program

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "DHT.h"

#define DHTPIN 4
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {

  lcd.init();
  lcd.backlight();

  dht.begin();

}

void loop() {

  float temp = dht.readTemperature();
  float hum = dht.readHumidity();

  lcd.clear();

  lcd.setCursor(0,0);
  lcd.print("Temp: ");
  lcd.print(temp);
  lcd.print(" C");

  lcd.setCursor(0,1);
  lcd.print("Hum: ");
  lcd.print(hum);
  lcd.print(" %");

  delay(2000);

}

Program Explanation

Code	Purpose
dht.readTemperature()	Reads temperature value
dht.readHumidity()	Reads humidity value
lcd.setCursor()	Sets LCD cursor position
lcd.print()	Displays text on LCD

Output

After uploading the code:

• LCD displays temperature value
• LCD displays humidity value
• Values update automatically every 2 seconds

Important Notes

• Common LCD I2C address is 0x27.
• If LCD does not work, try address 0x3F.
• DHT11 is slower compared to DHT22.
• Use proper USB cable for stable ESP32 operation.

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