Introduction
In this project, we will learn how to interface a 16×2 I2C LCD display with Arduino Uno. Using the I2C module reduces wiring complexity and makes your Arduino projects cleaner and easier to build.
This tutorial is perfect for:
-
Beginners learning Arduino
-
School robotics projects
-
IoT display systems
-
Sensor data monitoring projects
By the end of this guide, you’ll understand how to display text, sensor values, and custom messages on a 16×2 LCD using I2C communication.
Code:
/*
* 16x2 I2C LCD Display with Arduino
* Features: Text display, scrolling messages, custom characters, sensor readings
* I2C Address: 0x27 (or 0x3F)
*/
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
// Initialize LCD with I2C address 0x27, 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);
// Custom character definitions (heart, smile, degree symbol, etc.)
byte heart[8] = {
0b00000,
0b01010,
0b11111,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000
};
byte smile[8] = {
0b00000,
0b01010,
0b01010,
0b00000,
0b10001,
0b01110,
0b00000,
0b00000
};
byte degree[8] = {
0b00110,
0b01001,
0b01001,
0b00110,
0b00000,
0b00000,
0b00000,
0b00000
};
byte arrow[8] = {
0b00100,
0b01110,
0b11111,
0b00100,
0b00100,
0b00100,
0b00100,
0b00000
};
byte bell[8] = {
0b00100,
0b01110,
0b01110,
0b01110,
0b11111,
0b00000,
0b00100,
0b00000
};
// Variables for demonstration
int counter = 0;
unsigned long lastUpdate = 0;
const int updateInterval = 1000; // Update every second
void setup() {
Serial.begin(9600);
// Initialize LCD
lcd.init();
// Turn on backlight
lcd.backlight();
// Create custom characters
lcd.createChar(0, heart);
lcd.createChar(1, smile);
lcd.createChar(2, degree);
lcd.createChar(3, arrow);
lcd.createChar(4, bell);
// Display startup message
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("I2C LCD Display");
lcd.setCursor(0, 1);
lcd.print("Initializing...");
delay(2000);
// Clear and show welcome message
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Arduino + LCD");
lcd.setCursor(0, 1);
lcd.write(0); // Heart
lcd.print(" Hello World! ");
lcd.write(1); // Smile
delay(2000);
Serial.println("16x2 I2C LCD Display Initialized");
Serial.println("I2C Address: 0x27");
Serial.println("Displaying various examples...");
}
void loop() {
unsigned long currentMillis = millis();
// Cycle through different display examples
int example = (currentMillis / 5000) % 6; // Change example every 5 seconds
switch(example) {
case 0:
displayCounter();
break;
case 1:
displayTemperature();
break;
case 2:
displayCustomChars();
break;
case 3:
displayScrollingText();
break;
case 4:
displaySensorData();
break;
case 5:
displayClock();
break;
}
delay(100);
}
// Example 1: Counter Display
void displayCounter() {
static unsigned long lastCount = 0;
if (millis() - lastCount >= 1000) {
lastCount = millis();
counter++;
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Counter Display");
lcd.setCursor(0, 1);
lcd.print("Count: ");
lcd.print(counter);
Serial.print("Counter: ");
Serial.println(counter);
}
}
// Example 2: Temperature Display
void displayTemperature() {
static unsigned long lastTemp = 0;
static float temperature = 25.5;
if (millis() - lastTemp >= 1000) {
lastTemp = millis();
temperature += random(-10, 11) / 10.0; // Simulate temperature change
if (temperature < 0) temperature = 0;
if (temperature > 50) temperature = 50;
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Temperature:");
lcd.setCursor(0, 1);
lcd.print(temperature, 1);
lcd.write(2); // Degree symbol
lcd.print("C");
lcd.setCursor(10, 1);
lcd.print(temperature * 9/5 + 32, 1);
lcd.write(2);
lcd.print("F");
Serial.print("Temperature: ");
Serial.print(temperature);
Serial.println("°C");
}
}
// Example 3: Custom Characters Display
void displayCustomChars() {
static unsigned long lastChar = 0;
if (millis() - lastChar >= 1000) {
lastChar = millis();
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Custom Chars:");
lcd.setCursor(0, 1);
lcd.write(0); lcd.print(" ");
lcd.write(1); lcd.print(" ");
lcd.write(2); lcd.print(" ");
lcd.write(3); lcd.print(" ");
lcd.write(4); lcd.print(" ");
lcd.print("Icons!");
Serial.println("Displaying custom characters");
}
}
// Example 4: Scrolling Text
void displayScrollingText() {
static int scrollPos = 0;
static unsigned long lastScroll = 0;
String message = " Arduino 16x2 LCD Display - I2C Communication ";
if (millis() - lastScroll >= 300) {
lastScroll = millis();
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Scrolling Text:");
lcd.setCursor(0, 1);
String displayText = message.substring(scrollPos, scrollPos + 16);
lcd.print(displayText);
scrollPos++;
if (scrollPos > message.length() - 16) {
scrollPos = 0;
}
}
}
// Example 5: Sensor Data Display
void displaySensorData() {
static unsigned long lastSensor = 0;
static int lightLevel = 512;
static int humidity = 65;
if (millis() - lastSensor >= 1000) {
lastSensor = millis();
// Simulate sensor readings
lightLevel += random(-50, 51);
humidity += random(-5, 6);
lightLevel = constrain(lightLevel, 0, 1023);
humidity = constrain(humidity, 0, 100);
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Light: ");
lcd.print(lightLevel);
lcd.setCursor(0, 1);
lcd.print("Humidity: ");
lcd.print(humidity);
lcd.print("%");
Serial.print("Light: ");
Serial.print(lightLevel);
Serial.print(" | Humidity: ");
Serial.print(humidity);
Serial.println("%");
}
}
// Example 6: Clock Display
void displayClock() {
static unsigned long lastClock = 0;
static int seconds = 0;
static int minutes = 30;
static int hours = 12;
if (millis() - lastClock >= 1000) {
lastClock = millis();
seconds++;
if (seconds >= 60) {
seconds = 0;
minutes++;
if (minutes >= 60) {
minutes = 0;
hours++;
if (hours >= 24) {
hours = 0;
}
}
}
lcd.clear();
lcd.setCursor(0, 0);
lcd.print(" Digital Clock");
lcd.setCursor(3, 1);
if (hours < 10) lcd.print("0");
lcd.print(hours);
lcd.print(":");
if (minutes < 10) lcd.print("0");
lcd.print(minutes);
lcd.print(":");
if (seconds < 10) lcd.print("0");
lcd.print(seconds);
Serial.print("Time: ");
if (hours < 10) Serial.print("0");
Serial.print(hours);
Serial.print(":");
if (minutes < 10) Serial.print("0");
Serial.print(minutes);
Serial.print(":");
if (seconds < 10) Serial.print("0");
Serial.println(seconds);
}
}
Why Use I2C LCD Instead of Normal LCD?
A regular 16×2 LCD requires 6–12 connections.
With an I2C module, you only need 4 wires:
-
VCC
-
GND
-
SDA
-
SCL
This makes wiring simple and beginner-friendly.
Diagram.json:
{
"version": 1,
"author": "16x2 I2C LCD Display",
"editor": "wokwi",
"parts": [
{
"type": "wokwi-arduino-uno",
"id": "uno",
"top": 0,
"left": 0,
"attrs": {}
},
{
"type": "wokwi-lcd1602",
"id": "lcd1",
"top": -150.4,
"left": -179.2,
"attrs": {
"pins": "i2c"
}
}
],
"connections": [
[
"lcd1:GND",
"uno:GND.1",
"black",
[
"v0"
]
],
[
"lcd1:VCC",
"uno:5V",
"red",
[
"v0"
]
],
[
"lcd1:SDA",
"uno:A4",
"green",
[
"v0"
]
],
[
"lcd1:SCL",
"uno:A5",
"blue",
[
"v0"
]
]
],
"dependencies": {}
}
Components Required
-
Arduino Uno
-
16×2 LCD with I2C module
-
Jumper wires
-
USB cable
Step-by-Step Connection Guide
Step 1: Identify I2C Pins on Arduino Uno
| I2C Pin | Arduino Uno Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| SDA | A4 |
| SCL | A5 |
Step 2: Connect LCD to Arduino
-
Connect VCC → 5V
-
Connect GND → GND
-
Connect SDA → A4
-
Connect SCL → A5
Your wiring is now complete.
Step 3: Install Required Library
Open Arduino IDE:
-
Go to Sketch → Include Library → Manage Libraries
-
Search for LiquidCrystal I2C
-
Install the library
FAQ
Q1: What is the I2C address of my LCD?
Usually 0x27 or 0x3F.
Q2: Can I display sensor values?
Yes! You can use lcd.print(sensorValue);
Q3: Is this beginner friendly?
Yes, this is one of the easiest Arduino display projects.
Conclusion
The 16×2 I2C LCD Display using Arduino Uno is one of the most essential and beginner-friendly projects. With just four wires, you can display sensor data, messages, and real-time information easily.
This project is perfect for robotics students, IoT beginners, and electronics enthusiasts.
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