What is a 16x2 LCD Display?

A 16x2 LCD is a popular alphanumeric display that can show 2 lines of 16 characters each. Using an I2C adapter with this LCD reduces the number of required GPIOs from 6 to just 2, making it ideal for microcontroller-based projects like the ESP32.

Working Principle of I2C LCD

The I2C module converts the parallel interface of the LCD to a serial two-wire (I2C) interface. It communicates with the ESP32 over SDA and SCL lines. The LiquidCrystal_I2C library handles the low-level communication, allowing easy display control.

• Connect the I2C LCD to the ESP32 using SDA and SCL pins.
• Install the LiquidCrystal_I2C library in Arduino IDE.
• Initialize the LCD with its I2C address in the code.
• Print messages or sensor values on the LCD display.

Formula: No specific formula, just use `lcd.print()` to display text.

Components Required

• ESP32 development board
• 16x2 LCD with I2C module
• Jumper wires
• Breadboard (optional)
• USB cable

Pin Configuration of 16x2 I2C LCD

• GND: Connects to GND of ESP32
• VCC: Connects to 3.3V or 5V of ESP32
• SDA: Serial Data line
• SCL: Serial Clock line

Typical I2C address for the LCD is 0x27 or 0x3F. Use I2C scanner code to find yours if unsure.

Wiring 16x2 I2C LCD to ESP32

• VCC -> 3.3V or 5V
• GND -> GND
• SDA -> GPIO 21
• SCL -> GPIO 22

Arduino Code for ESP32 + 16x2 I2C LCD

1#include <Wire.h>
2#include <LiquidCrystal_I2C.h>
3
4LiquidCrystal_I2C lcd(0x27, 16, 2);
5
6void setup() {
7  lcd.init();
8  lcd.backlight();
9  lcd.setCursor(0, 0);
10  lcd.print("Hello, ESP32!");
11  lcd.setCursor(0, 1);
12  lcd.print("LCD I2C Ready");
13}
14
15void loop() {
16  // Nothing here for now
17}

Code Explanation (Line-by-Line)

• #include <Wire.h>: Includes the Wire library for I2C communication.
• #include <LiquidCrystal_I2C.h>: Includes the LCD library to control the 16x2 display over I2C.
• LiquidCrystal_I2C lcd(0x27, 16, 2);: Creates an LCD object with I2C address 0x27 and 16x2 display size.
• lcd.init();: Initializes the LCD screen.
• lcd.backlight();: Turns on the LCD backlight.
• lcd.setCursor(0, 0); lcd.print(...);: Sets cursor position and prints text on line 1.
• lcd.setCursor(0, 1); lcd.print(...);: Prints text on the second line of the display.

Applications

• Real-time display of sensor data
• Weather station readouts
• Home automation displays
• IoT dashboards
• DIY menu systems

Conclusion

Interfacing a 16x2 LCD with ESP32 using I2C is an effective way to add visual feedback to your IoT or embedded projects. With just two wires, it simplifies wiring and provides a clean method to display useful data and messages.