Arduino UNO R4 - LCD I2C
This tutorial instructs you how to use a 16x2 LCD I2C interface with an Arduino UNO R4. In detail, We will learn:
- How to connect LCD I2Cto Arduino UNO R4
- How to program Arduino UNO R4 to display text on LCD I2C
- How to program Arduino UNO R4 to display numbers on LCD I2C
- How to program Arduino UNO R4 to display custom characters on LCD I2C
Hardware Preparation
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.
Additionally, some of these links are for products from our own brand, DIYables.
Overview of LCD I2C 16x2
The 16x2 LCD I2C is a display featuring 16 columns and 2 rows. It is equipped with an I2C interface and includes a potentiometer for contrast adjustment.
Pinout
The LCD I2C connects through an I2C interface and has 4 pins.
- GND pin: connect to GND (0 volts).
- VCC pin: connect to VCC for power (5 volts).
- SDA pin: carries I2C data signal.
- SCL pin: carries I2C clock signal.
LCD Coordinate
The LCD I2C 16x2 has 16 columns and 2 rows. Both columns and rows start numbering from 0.
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
| LCD I2C | Arduino UNO R4, Nano | Arduino Mega |
|---|---|---|
| Vin | 5V | 5V |
| GND | GND | GND |
| SDA | A4 | 20 |
| SCL | A5 | 21 |
How To Program For LCD I2C
Using the LiquidCrystal_I2C library makes handling the LCD very easy.
- Include the library:
#include <LiquidCrystal_I2C.h>
- Create a LiquidCrystal_I2C object by specifying its I2C address, the number of columns, and the number of rows.
LiquidCrystal_I2C lcd(0x27, 16, 2); // Initialize the LCD with I2C address 0x27 for a 16x2 display
- Set up the LCD screen.
lcd.init(); // Initialize the LCD display
lcd.backlight(); // Turn on the backlight of the LCD
- Place the cursor at the chosen spot (column_index, row_index).
lcd.setCursor(column_index, row_index);
- Display a message on the LCD screen.
lcd.print("Hello World!");
We can do many more things with an LCD (see the 'Do More with LCD' section).
※ NOTE THAT:
The I2C address for the LCD might be different depending on the manufacturer. In our code, we used the address 0x27 as specified by the manufacturer DIYables.
Arduino UNO R4 Code
#include <LiquidCrystal_I2C.h>
// Initialize an LCD object for a 16x2 character LCD using I2C
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup() {
lcd.init(); // Initialize the LCD
lcd.backlight(); // Enable the LCD backlight
}
void loop() {
lcd.clear(); // Clear any previously written content
lcd.setCursor(0, 0); // Position cursor at top left corner
lcd.print("Arduino UNO R4"); // Display text in the first line
lcd.setCursor(2, 1); // Position cursor in the second line at third character
lcd.print("GetStarted.com"); // Display text in the second line
delay(2000); // Pause for 2 seconds
lcd.clear(); // Clear the LCD screen for next message
lcd.setCursor(3, 0); // Position cursor in the first line, fourth character
lcd.print("DIYables"); // Display text in the first line
lcd.setCursor(0, 1); // Position cursor at the start of the second line
lcd.print("www.diyables.io"); // Display website URL in the second line
delay(2000); // Hold the displayed text for 2 seconds
Detailed Instructions
Follow these instructions step by step:
- If this is your first time using the Arduino Uno R4 WiFi/Minima, refer to the tutorial on setting up the environment for Arduino Uno R4 WiFi/Minima in the Arduino IDE.
- Connect LCD I2C display to Arduino UNO R4 according to the provided diagram.
- Connect the Arduino Uno R4 board to your computer using a USB cable.
- Launch the Arduino IDE on your computer.
- Select the appropriate Arduino Uno R4 board (e.g., Arduino Uno R4 WiFi) and COM port.
- Go to the Libraries icon on the left side of the Arduino IDE.
- Type "LiquidCrystal I2C" in the search box and look for the LiquidCrystal_I2C library by Frank de Brabander.
- Press the Install button to install the LiquidCrystal_I2C library.
- Copy the code and open it in Arduino IDE
- Click the Upload button in Arduino IDE to upload the code to Arduino UNO R4
- Check out the result on the LCD screen
- Try changing the text and its location
Video Tutorial
Do More with LCD
Custom Character
To show special characters or symbols like a heart or an angry bird on an LCD, you must use the character generator because the lcd.print() function can only display ASCII characters.
The LCD 16x2 can show 32 characters across 2 lines, with 16 spots on each line. Every character uses 40 tiny squares, arranged in 8 lines and 5 columns.
The character generator creates a character (40 pixels). You only need to follow these 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>
// Initialize the LCD connected via I2C at address 0x27 with 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);
// Define byte array for creating custom character shape
byte customChar[8] = {
0b00000,
0b01010,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000,
0b00000
};
void setup() {
lcd.init(); // Initialize LCD screen
lcd.backlight(); // Turn on the backlight
lcd.createChar(0, customChar); // Register the custom character on LCD with ID 0
lcd.setCursor(2, 0); // Set cursor to start at column 2, row 0
lcd.write((byte)0); // Display the custom character at the current cursor position
}
void loop(){
}
Result displayed on the screen:
Multiple custom characters
We can make up to 8 special characters (numbered from 0 to 7). The example below shows how to create and display three characters.
#include <LiquidCrystal_I2C.h>
// Create an LCD object, using I2C address 0x27 with 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);
// Define custom character 0 (heart shape)
byte customChar0[8] = {
0b00000,
0b01010,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000,
0b00000
};
// Define custom character 1 (arrow pointing upwards)
byte customChar1[8] = {
0b00100,
0b01110,
0b11111,
0b00100,
0b00100,
0b00100,
0b00100,
0b00100
};
// Define custom character 2 (arrow pointing downwards)
byte customChar2[8] = {
0b00100,
0b00100,
0b00100,
0b00100,
0b00100,
0b11111,
0b01110,
0b00100
};
void setup() {
lcd.init(); // Initialize the LCD display
lcd.backlight(); // Turn on the LCD backlight
// Register custom character 0 with index 0 on the LCD
lcd.createChar(0, customChar0);
// Register custom character 1 with index 1 on the LCD
lcd.createChar(1, customChar1);
// Register custom character 2 with index 2 on the LCD
lcd.createChar(2, customChar2);
// Set the cursor to column 2, row 0
lcd.setCursor(2, 0);
// Display the custom character 0 at the current cursor position
lcd.write((byte)0);
// Set the cursor to column 4, row 0
lcd.setCursor(4, 0);
// Display the custom character 1 at the current cursor position
lcd.write((byte)1);
// Set the cursor to column 6, row 0
lcd.setCursor(6, 0);
// Display the custom character 2 at the current cursor position
lcd.write((byte)2);
}
void loop() {
}
Result displayed on liquid-crystal display (LCD):
Summary: how to use custom character on LCD
- Use the character generator above to make binary code for your special character.
- Write down the binary code for your character (copy from the previous step).
byte customChar[8] = {
0b00000,
0b01010,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000,
0b00000
};
- Make a personalized character and place it at a number between 0 and 7 in the setup() function.
lcd.createChar(index, customChar);
- Display a special character on the LCD whenever you want, either in the setup() or loop() function.
lcd.setCursor(column, row); // Set the cursor to the specified column and row
lcd.write((byte)index); // Display the custom character stored at 'index' position
Other functions
Insert the following functions into the loop() function one by one, adding a delay(5000) after each function.
- Easy-to-read LCD display
lcd.clear();
- Place the cursor in the top-left corner of the screen.
lcd.home();
- Position the cursor at a specific place (column, row).
lcd.setCursor(column, row);
- Show the LCD screen cursor.
lcd.cursor();
- Turns off the LCD screen cursor.
lcd.noCursor();
- Show the flashing LCD cursor.
lcd.blink()
- Stops the flashing LCD cursor.
lcd.noBlink()
- Find additional information at LiquidCrystal Library Reference.
Troubleshooting on LCD I2C
If the text does not appear on the LCD I2C, please check these issues:
- Change the LCD screen brightness by turning the potentiometer on its back.
- The I2_SELF CONT presence of the LCD might vary with different makers. It usually is 0x27 or 0x3F. Test these addresses individually. If neither works, use the following code to discover the correct 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 outcome displayed on the Serial Monitor:
COM6
Scanning...
I2C device found at address 0x3F !
done
Scanning...
I2C device found at address 0x3F !
done
Autoscroll
Clear output
9600 baud
Newline