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INTERNET OF THING (IoT)

LIBRARIES

Arduino - LCD I2C

In this Arduino LCD I2C tutorial, we will learn how to connect an LCD I2C (Liquid Crystal Display) to the Arduino board. LCDs are very popular and widely used in electronics projects for displaying information. There are many types of LCD. This tutorial takes LCD 16x2 (16 columns and 2 rows) as an example. The other LCDs are similar.

Hardware Required

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	LCD I2C
1	×	Jumper Wires
1	×	(Recommended) Screw Terminal Block Shield for Arduino Uno
1	×	(Recommended) Breadboard Shield For Arduino Uno
1	×	(Recommended) Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables.

About LCD I2C 16x2

In the previous tutorial, we had learned how to use the normal LCD. However, wiring between Arduino and the normal LCD is complicated. Therefore, LCD I2C has been created to simplify the wiring. Actually, LCD I2C is composed of a normal LCD, an I2C module and a potentiometer.

Pinout

LCD I2C uses I2C interface, so it has 4 pins:

GND pin: needs to be connected to GND (0V).
VCC pin: the power supply for the LCD, needs to be connected to VCC (5V).
SDA pin: I2C data signal
SCL pin: I2C clock signal

LCD I2C Pinout

LCD Coordinate

LCD I2C 16x2 includes 16 columns and 2 rows. the conlums and rows are indexed from 0.

Arduino LCD I2C Coordinate

Wiring Diagram

Arduino LCD I2C Wiring Diagram

This image is created using Fritzing. Click to enlarge image

LCD I2C	Arduino Uno, Nano	Arduino Mega
Vin	5V	5V
GND	GND	GND
SDA	A4	20
SCL	A5	21

How To Program For LCD I2C

Thanks to the LiquidCrystal_I2C library, the using LCD is a piece of cake.

Include the library:

#include <LiquidCrystal_I2C.h> // Library for LCD

Declare a LiquidCrystal_I2C object with I2C address, the number of columns, the number of rows:

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows

Initialize the LCD.

lcd.init(); //initialize the lcd lcd.backlight(); //open the backlight

Move cursor to the desired position (column_index, row_index)

lcd.setCursor(column_index, row_index);

Print a message to the LCD.

lcd.print("Hello World!");

There are many things more that we can do with LCD (see Do More with LCD part)

※ NOTE THAT:

The I2C address of LCD can vary according to the manufacturers. In the code, we used 0x27 that is specified by DIYables brand

Arduino Code

#include <LiquidCrystal_I2C.h> LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows void setup() { lcd.init(); // initialize the lcd lcd.backlight(); } void loop() { lcd.clear(); // clear display lcd.setCursor(0, 0); // move cursor to (0, 0) lcd.print("Arduino"); // print message at (0, 0) lcd.setCursor(2, 1); // move cursor to (2, 1) lcd.print("GetStarted.com"); // print message at (2, 1) delay(2000); // display the above for two seconds lcd.clear(); // clear display lcd.setCursor(3, 0); // move cursor to (3, 0) lcd.print("DIYables"); // print message at (3, 0) lcd.setCursor(0, 1); // move cursor to (0, 1) lcd.print("www.diyables.io"); // print message at (0, 1) delay(2000); // display the above for two seconds }

Quick Steps

Navigate to the Libraries icon on the left bar of the Arduino IDE.
Search "LiquidCrystal I2C", then find the LiquidCrystal_I2C library by Frank de Brabander
Click Install button to install LiquidCrystal_I2C library.

Arduino LiquidCrystal I2C library

Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino
See the result on LCD

Arduino display text on LCD

image source: diyables.io

Try modifying text and position

LCD I2C Selection Guide

There are various types of LCD I2C displays available in the market, mainly differing in background color and the shape of the I2C interface module.

LCD I2C Selection Guide

Regarding color, these displays usually come in two background colors: green and blue.

For the I2C interface module shape, there are two main aspects to consider:

Potentiometer size: This includes options for thin and thick potentiometers.

Thick potentiometer: Easier to adjust but occupies more space.
Thin potentiometer: More compact, saving space with its smaller height.

I2C selection jumper:

With jumper: Allows switching between two I2C addresses, useful when your code uses two LCD displays simultaneously. However, it can cause confusion with I2C addresses when only one LCD is used and it also requires more space.
Without jumper: This has a fixed I2C address and is very convenient when your code uses just one LCD display. Since most applications use only one LCD, this type is highly recommended.

Video Tutorial

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Do More with LCD

Custom Character

lcd.print() function supports only ASCII characters. If you want to display a special character or symbol (e.g. heart, angry bird), you need to use the below character generator.

LCD 16x2 can display 32 characters (2 rows and 16 columns). Each character is composed of 40 pixels (8 rows and 5 columns).

Arduino LCD 16x2 Pixel

The character generator represents a character (40 pixels). You just need to do the following steps:

Click on each pixel to select/deselect

Copy below custom character code

Replace the customChar[8] in the below code

#include <LiquidCrystal_I2C.h> LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows byte customChar[8] = { 0b00000, 0b01010, 0b11111, 0b11111, 0b01110, 0b00100, 0b00000, 0b00000 }; void setup() { lcd.init(); // initialize the lcd lcd.backlight(); lcd.createChar(0, customChar); // create a new custom character lcd.setCursor(2, 0); // move cursor to (2, 0) lcd.write((byte)0); // print the custom char at (2, 0) } void loop() { }

Result on LCD:

LCD custom character

Multiple custom characters

We can create up to 8 custom characters (indexed 0 to 7). The below example creates and displays three characters.

#include <LiquidCrystal_I2C.h> LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27, 16 column and 2 rows byte customChar0[8] = { 0b00000, 0b01010, 0b11111, 0b11111, 0b01110, 0b00100, 0b00000, 0b00000 }; byte customChar1[8] = { 0b00100, 0b01110, 0b11111, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100 }; byte customChar2[8] = { 0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0b11111, 0b01110, 0b00100 }; void setup() { lcd.init(); // initialize the lcd lcd.backlight(); lcd.createChar(0, customChar0); // create a new custom character (index 0) lcd.createChar(1, customChar1); // create a new custom character (index 1) lcd.createChar(2, customChar2); // create a new custom character (index 2) lcd.setCursor(2, 0); // move cursor to (2, 0) lcd.write((byte)0); // print the custom char 0 at (2, 0) lcd.setCursor(4, 0); // move cursor to (4, 0) lcd.write((byte)1); // print the custom char 1 at (4, 0) lcd.setCursor(6, 0); // move cursor to (6, 0) lcd.write((byte)2); // print the custom char 2 at (6, 0) } void loop() { }

Result on LCD:

LCD multiple custom characters

Summary: how to use custom character on LCD

Use the above character generator to create binary code for the custom character.
Declare the binary code for the custom character (copy from above step)

byte customChar[8] = { 0b00000, 0b01010, 0b11111, 0b11111, 0b01110, 0b00100, 0b00000, 0b00000 };

Create custom character and assign to an index value (from 0 to 7) in setup() function

lcd.createChar(index, customChar);

Print the custom character in LCD anytime, anywhere (in setup() or loop() function)

lcd.setCursor(column, row); // move cursor to a desired position lcd.write((byte)index); // print the custom char at the desired position

Other functions

Add the below functions into loop() function one by one. And add delay(5000) after each function

Clear LCD screen

lcd.clear();

Move the cursor to the upper-left of the LCD

lcd.home();

Move the cursor to the a position (column, row)

lcd.setCursor(column, row);

Display the LCD cursor

lcd.cursor();

Hides the LCD cursor.

lcd.noCursor();

Display the blinking LCD cursor

lcd.blink()

Turns off the blinking LCD cursor.

lcd.noBlink()

And more at LiquidCrystal Library Reference

Challenge Yourself

Use LCD to do one of the following projects:

Sending text from PC (via Serial Monitor) and display on LCD. Hint: Refer to How to send data from PC to Aduino
Displaying the pressed key of the keypad on LCD. Hint: Refer to Arduino - Keypad

Troubleshooting on LCD I2C

If the text is not displayed on LCD I2C, please check the following issues:

Adjust the brightness of LCD by rotating potentiometer in the backside of LCD
Depending on manufacturers, the I2C address of LCD may be different. Usually, the default I2C address of LCD is 0x27 or 0x3F. Try these values one by one. If you still failed, run the below code to find the I2C address.

// I2C address scanner program #include <Wire.h> void setup() { Wire.begin(); Serial.begin(9600); Serial.println("I2C Scanner"); } void loop() { byte error, address; int nDevices; Serial.println("Scanning..."); nDevices = 0; for(address = 1; address < 127; address++ ) { Wire.beginTransmission(address); error = Wire.endTransmission(); if (error == 0) { Serial.print("I2C device found at address 0x"); if (address < 16) Serial.print("0"); Serial.print(address,HEX); Serial.println(" !"); nDevices++; } else if (error==4) { Serial.print("Unknown error at address 0x"); if (address < 16) Serial.print("0"); Serial.println(address,HEX); } } if (nDevices == 0) Serial.println("No I2C devices found"); else Serial.println("done"); delay(5000); // wait 5 seconds for next scan }

The result on Serial Monitor:

COM6

Send

Scanning... I2C device found at address 0x3F ! done Scanning... I2C device found at address 0x3F ! done

Autoscroll Show timestamp

Clear output

9600 baud

Newline

The Best Arduino Starter Kit

See the best Arduino kit for beginner

See Also

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