How to use LCD on Arduino?

 You use an LCD on Arduino by doing two things:

1. Wire it correctly

2. Use the LiquidCrystal (or I2C) library in your sketch

I’ll show you both the classic 16×2 LCD with parallel pins and the I2C backpack version.

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1. The LCD we’re talking about

Most tutorials (and this answer) assume a 16×2 character LCD that’s “HD44780-compatible”, like this:

• 16 characters × 2 lines

• Pins: VSS, VDD, VO, RS, RW, E, D0–D7, A, K

If yours has only 4 pins (GND, VCC, SDA, SCL) → that’s an I2C backpack version. I’ll cover that in section 4.

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2. Wiring a 16×2 LCD directly to Arduino (4-bit mode)

We’ll use 4 data lines (D4–D7) to save pins.

Parts:

• Arduino Uno (any board is fine)

• 16×2 LCD

• 10 kΩ potentiometer (for contrast)

• Some jumper wires

• Optional: 220 Ω resistor for LCD backlight

Typical wiring table (4-bit mode)

Assume these connections:

LCD Pin	Name	Connect To
1	VSS	GND
2	VDD	+5V
3	VO	Middle pin of 10k pot (contrast)
		Pot side 1 → GND, side 2 → +5V
4	RS	Arduino D12
5	RW	GND (we only write to LCD)
6	E	Arduino D11
11	D4	Arduino D5
12	D5	Arduino D4
13	D6	Arduino D3
14	D7	Arduino D2
15	A	+5V through ~220 Ω (backlight +)
16	K	GND (backlight –)

(If numbering on your module is slightly different, just match by pin name.)

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3. Basic Arduino code with LiquidCrystal

The Arduino IDE already has the LiquidCrystal library.

Example sketch: “Hello, world!”

#include <LiquidCrystal.h>

// LiquidCrystal(rs, enable, d4, d5, d6, d7);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // Initialize 16 columns, 2 rows:
  lcd.begin(16, 2);

  lcd.print("Hello, world!");
  delay(2000);

  lcd.clear();
  lcd.setCursor(0, 0);      // col 0, row 0
  lcd.print("Line 1: Hi");
  lcd.setCursor(0, 1);      // col 0, row 1
  lcd.print("Line 2: LCD :)");
}

void loop() {
  // Optional: simple counter demo
  static int counter = 0;
  lcd.setCursor(10, 1);     // print at end of second line
  lcd.print(counter);
  lcd.print("  ");          // overwrite old digits
  counter++;
  delay(500);
}

Upload this, then:

• Adjust the contrast pot until you see characters clearly.

• If nothing lights → check backlight connections (pins 15 & 16).

• If boxes appear but no text → wiring or lcd.begin(16, 2) might be wrong.

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4. Using an I2C LCD (backpack module)

If your LCD has a small board with 4 pins: GND, VCC, SDA, SCL:

Wiring:

For Arduino Uno / Nano:

• GND → GND

• VCC → 5V

• SDA → A4

• SCL → A5

(For other boards, SDA/SCL pins differ – check board pinout.)

Library

You’ll usually need a library like LiquidCrystal_I2C.

In Arduino IDE:

1. Sketch → Include Library → Manage Libraries…

2. Search for LiquidCrystal I2C

3. Install something like LiquidCrystal I2C by Frank de Brabander (or similar)

Example sketch (I2C LCD):

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

// Most modules use address 0x27 or 0x3F.
// If text doesn’t appear, try the other address.
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  lcd.init();           // Initialize the LCD
  lcd.backlight();      // Turn on backlight

  lcd.setCursor(0, 0);
  lcd.print("Hello I2C LCD!");
  lcd.setCursor(0, 1);
  lcd.print("Arduino rocks!");
}

void loop() {
  // simple blink text
  lcd.noBacklight();
  delay(500);
  lcd.backlight();
  delay(500);
}

If nothing shows:

• Try address 0x3F instead of 0x27.

• Check wiring of SDA/SCL.

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5. Handy tricks

• Clear the display: lcd.clear();

• Move cursor: lcd.setCursor(col, row);

• Scroll text:

  lcd.scrollDisplayLeft();
  lcd.scrollDisplayRight();
  

• Custom characters: you can define your own icons with lcd.createChar() (using a 5×8 pixel pattern).