Introduction

The LCD1602 display module is a classic parallel interface character LCD featuring a 16×2 character display with blue backlight. These displays use the HD44780 controller or compatible chips and are widely supported in the maker community.

Key Features

Technical Specifications

Pin Configuration

Pin	Symbol	Description	Arduino Connection
1	VSS	Ground	GND
2	VDD	Power (+5V)	5V
3	VO	Contrast adjustment	Potentiometer
4	RS	Register Select	Digital Pin
5	RW	Read/Write	GND (for write only)
6	E	Enable	Digital Pin
7-14	DB0-DB7	Data Bus	Digital Pins (4-bit: DB4-DB7)
15	A	Backlight Anode (+)	5V via resistor
16	K	Backlight Cathode (-)	GND

Wiring with Arduino

4-Bit Mode Connection

// Typical 4-bit connections:
// LCD RS → Arduino D12
// LCD E → Arduino D11
// LCD D4 → Arduino D5
// LCD D5 → Arduino D4
// LCD D6 → Arduino D3
// LCD D7 → Arduino D2
// LCD R/W → GND
// LCD VSS → GND
// LCD VDD → 5V
// LCD VO → Potentiometer center pin
// LCD A → 5V (with resistor)
// LCD K → GND

Contrast Adjustment

Connect pin 3 (VO) to a 10K potentiometer between VCC and GND for contrast control.

Arduino Library Setup

1. Install the LiquidCrystal library (included with Arduino IDE)
2. Include the library in your sketch:

   #include <LiquidCrystal.h>

3. Initialize the display with your pin configuration:

// Initialize with (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

Basic Display Example

#include <LiquidCrystal.h>

// Initialize the library with pin numbers
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // Set up the LCD's number of columns and rows
  lcd.begin(16, 2);
  
  // Print a message to the LCD
  lcd.print("Hello, World!");
}

void loop() {
  // Set the cursor to column 0, line 1
  lcd.setCursor(0, 1);
  
  // Print the number of seconds since reset
  lcd.print(millis() / 1000);
}

Advanced Features

// Create custom character
byte heart[8] = {
  0b00000,
  0b01010,
  0b11111,
  0b11111,
  0b01110,
  0b00100,
  0b00000,
  0b00000
};

void setup() {
  lcd.createChar(0, heart);
  lcd.write(byte(0));
}

void scrollText(String message) {
  for (int i=0; i < message.length(); i++) {
    lcd.scrollDisplayLeft();
    lcd.print(message[i]);
    delay(300);
  }
}

// Connect backlight through transistor
// or MOSFET for PWM control
void setBacklight(int brightness) {
  analogWrite(backlightPin, brightness);
}

// Use different enable pins
LiquidCrystal lcd1(12, 11, 5, 4, 3, 2);
LiquidCrystal lcd2(12, 10, 5, 4, 3, 2);

Troubleshooting