How to Display Custom Character on LCD Arduino Easily

To display a custom character on an Arduino LCD, use the createChar() function to define the character's pixel pattern, then use lcd.write() to show it. First, create a byte array for the character, load it into the LCD's memory, and finally print it by its index.

Syntax

The main functions to display a custom character on an Arduino LCD are:

• lcd.createChar(location, charmap): Defines a custom character at a memory location (0-7) using an 8-byte charmap array.
• lcd.write(location): Displays the custom character stored at the given location.

The charmap is an array of 8 bytes, each byte representing a row of 5 pixels (bits 0-4) on the LCD character cell.

arduino

byte smiley[8] = {
  0b00000,
  0b01010,
  0b01010,
  0b00000,
  0b10001,
  0b01110,
  0b00000,
  0b00000
};

lcd.createChar(0, smiley);
lcd.setCursor(0, 0);
lcd.write(byte(0));

Example

This example shows how to create a smiley face custom character and display it on the LCD at position (0,0).

arduino

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

byte smiley[8] = {
  0b00000,
  0b01010,
  0b01010,
  0b00000,
  0b10001,
  0b01110,
  0b00000,
  0b00000
};

void setup() {
  lcd.begin(16, 2);
  lcd.createChar(0, smiley);  // Store custom char at location 0
  lcd.setCursor(0, 0);
  lcd.write(byte(0));         // Display custom char
  lcd.print(" Hello!");
}

void loop() {
  // Nothing here
}

Output

A smiley face character appears at the top-left corner of the LCD followed by the text " Hello!"

Common Pitfalls

• Not using byte() cast in lcd.write(): You must cast the location number to byte to display the custom character correctly.
• Defining more than 8 custom characters: The LCD only supports 8 custom characters (locations 0-7).
• Incorrect pixel pattern: Each byte must only use the lower 5 bits for pixels; higher bits are ignored.
• Not calling lcd.createChar() before lcd.write(): The character must be loaded into LCD memory first.

arduino

/* Wrong way: Missing byte cast */
lcd.write(0);  // May print wrong character

/* Right way: Use byte cast */
lcd.write(byte(0));  // Correct display

Quick Reference

Function	Purpose	Notes
lcd.createChar(location, charmap)	Define custom character at location 0-7	charmap is 8 bytes, each byte 5 pixels wide
lcd.write(byte(location))	Display custom character stored at location	Must cast location to byte
lcd.setCursor(col, row)	Set cursor position on LCD	Before printing characters
lcd.print(text)	Print text on LCD	Can mix with custom chars

Key Takeaways

Use lcd.createChar() with a byte array to define custom characters before displaying.

Only 8 custom characters (locations 0-7) can be stored at once on the LCD.

Always cast the location to byte in lcd.write() to show the custom character correctly.

Each custom character is an 8-row, 5-pixel wide pattern defined by bytes.

Set the cursor position before printing custom characters or text.