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How to Use I2C LCD with ESP32 on Arduino IDE (ESP8266 compatible)

This tutorial shows how to use the I2C LCD (Liquid Crystal Display) with the ESP32 using Arduino IDE. We’ll show you how to wire the display, install the library and try sample code to write text on the LCD: static text, and scroll long messages. You can also use this guide with the ESP8266.

16×2 I2C Liquid Crystal Display

For this tutorial we’ll be using a 16×2 I2C LCD display, but LCDs with other sizes should also work.

The advantage of using an I2C LCD is that the wiring is really simple. You just need to wire the SDA and SCL pins.

Additionally, it comes with a built-in potentiometer you can use to adjust the contrast between the background and the characters on the LCD. On a “regular” LCD you need to add a potentiometer to the circuit to adjust the contrast.

Parts Required

To follow this tutorial you need these parts:

  • ESP32 DOIT DEVKIT V1 Board – read ESP32 Development Boards Review and Comparison
  • Optional – ESP8266 12-E – read Best ESP8266 Wi-Fi Development Boards
  • 16×2 I2C Liquid Crystal Display (LCD)
  • Female to female jumper wires

Wiring the LCD to the ESP32

This display uses I2C communication, which makes wiring really simple.

Wire your LCD to the ESP32 by following the next schematic diagram. We’re using the ESP32 default I2C pins (GPIO 21 and GPIO 22).

You can also use the following table as a reference.

I2C LCDESP32
GNDGND
VCCVIN
SDAGPIO 21
SCLGPIO 22

Wiring the LCD to the ESP8266

You can also wire your LCD to the ESP8266 by following the next schematic diagram. We’re using the ESP8266 default I2C pins (GPIO 4 and GPIO 5).

You can also use the following table as a reference.

I2C LCDESP8266
GNDGND
VCCVIN
SDAGPIO 4 (D2)
SCLGPIO 5 (D1)

Preparing the Arduino IDE

Before proceeding with the project, you need to install the ESP32 or ESP8266 add-on in the Arduino IDE.

Arduino IDE with ESP32

Follow one of the next guides to prepare your Arduino IDE to work with the ESP32:

Arduino IDE with ESP8266

To install the ESP8266 add-on in your Arduino IDE, read the following tutorial: How to Install the ESP8266 Board in Arduino IDE.

Installing the LiquidCrystal_I2C Library

There are several libraries that work with the I2C LCD. We’re using this library by Marco Schwartz. Follow the next steps to install the library:

  1. Click here to download the LiquidCrystal_I2C library. You should have a .zip folder in your Downloads
  2. Unzip the .zip folder and you should get LiquidCrystal_I2C-master folder
  3. Rename your folder from LiquidCrystal_I2C-master to LiquidCrystal_I2C
  4. Move the LiquidCrystal_I2C folder to your Arduino IDE installation libraries folder
  5. Finally, re-open your Arduino IDE

Getting the LCD Address

Before displaying text on the LCD, you need to find the LCD I2C address. With the LCD properly wired to the ESP32, upload the following I2C Scanner sketch.

/*********
Gnd_To_Vcc 
*********/

#include <Wire.h>
 
void setup() {
  Wire.begin();
  Serial.begin(115200);
  Serial.println("\nI2C 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.println(address,HEX);
      nDevices++;
    }
    else if (error==4) {
      Serial.print("Unknow error at address 0x");
      if (address<16) {
        Serial.print("0");
      }
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0) {
    Serial.println("No I2C devices found\n");
  }
  else {
    Serial.println("done\n");
  }
  delay(5000);          
}

After uploading the code, open the Serial Monitor at a baud rate of 115200. Press the ESP32 EN button. The I2C address should be displayed in the Serial Monitor.

In this case the address is 0x27. If you’re using a similar 16×2 display, you’ll probably get the same address.

Display Static Text on the LCD

Displaying static text on the LCD is very simple. All you have to do is select where you want the characters to be displayed on the screen, and then send the message to the display.

Here’s a very simple sketch example that displays “Hello, World!“.

/*********
  Gnd_To_Vcc
*********/

#include <LiquidCrystal_I2C.h>

// set the LCD number of columns and rows
int lcdColumns = 16;
int lcdRows = 2;

// set LCD address, number of columns and rows
// if you don't know your display address, run an I2C scanner sketch
LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows);  

void setup(){
  // initialize LCD
  lcd.init();
  // turn on LCD backlight                      
  lcd.backlight();
}

void loop(){
  // set cursor to first column, first row
  lcd.setCursor(0, 0);
  // print message
  lcd.print("Hello, World!");
  delay(1000);
  // clears the display to print new message
  lcd.clear();
  // set cursor to first column, second row
  lcd.setCursor(0,1);
  lcd.print("Hello, World!");
  delay(1000);
  lcd.clear(); 
}

It displays the message in the first row, and then in the second row.

In this simple sketch we show you the most useful and important functions from the LiquidCrystal_I2C library. So, let’s take a quick look at how the code works.

How the code works

First, you need to include theLiquidCrystal_I2C library.

#include <LiquidCrystal_I2C.h>

https://tpc.googlesyndication.com/safeframe/1-0-37/html/container.html

The next two lines set the number of columns and rows of your LCD display. If you’re using a display with another size, you should modify those variables.

int lcdColumns = 16;
int lcdRows = 2;

Then, you need to set the display address, the number of columns and number of rows. You should use the display address you’ve found in the previous step.

LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows);

In the setup(), first initialize the display with the init() method.

lcd.init();

Then, turn on the LCD backlight, so that you’re able to read the characters on the display.

lcd.backlight();

To display a message on the screen, first you need to set the cursor to where you want your message to be written. The following line sets the cursor to the first column, first row.

lcd.setCursor(0, 0);

Note: 0 corresponds to the first column, 1 to the second column, and so on…

Then, you can finally print your message on the display using the print() method.

lcd.print("Hello, World!");

Wait one second, and then clean the display with the clear() method.

lcd.clear();

After that, set the cursor to a new position: first column, second row.

lcd.setCursor(0,1);

Then, the process is repeated.

So, here’s a summary of the functions to manipulate and write on the display:

  • lcd.init(): initializes the display
  • lcd.backlight(): turns the LCD backlight on
  • lcd.setCursor(int column, int row): sets the cursor to the specified column and row
  • lcd.print(String message): displays the message on the display
  • lcd.clear(): clears the display

https://tpc.googlesyndication.com/safeframe/1-0-37/html/container.html

This example works well to display static text no longer than 16 characters.

Display Scrolling Text on the LCD

Scrolling text on the LCD is specially useful when you want to display messages longer than 16 characters. The library comes with built-in functions that allows you to scroll text. However, many people experience problems with those functions because:

  • The function scrolls text on both rows. So, you can’t have a fixed row and a scrolling row;
  • It doesn’t work properly if you try to display messages longer than 16 characters.

So, we’ve created a sample sketch with a function you can use in your projects to scroll longer messages.

The following sketch displays a static message in the first row and a scrolling message longer than 16 characters in the second row.

/*********
 Gnd_To_Vcc 
*********/

#include <LiquidCrystal_I2C.h>

// set the LCD number of columns and rows
int lcdColumns = 16;
int lcdRows = 2;

// set LCD address, number of columns and rows
// if you don't know your display address, run an I2C scanner sketch
LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows);  

String messageStatic = "Static message";
String messageToScroll = "This is a scrolling message with more than 16 characters";

// Function to scroll text
// The function acepts the following arguments:
// row: row number where the text will be displayed
// message: message to scroll
// delayTime: delay between each character shifting
// lcdColumns: number of columns of your LCD
void scrollText(int row, String message, int delayTime, int lcdColumns) {
  for (int i=0; i < lcdColumns; i++) {
    message = " " + message;  
  } 
  message = message + " "; 
  for (int pos = 0; pos < message.length(); pos++) {
    lcd.setCursor(0, row);
    lcd.print(message.substring(pos, pos + lcdColumns));
    delay(delayTime);
  }
}

void setup(){
  // initialize LCD
  lcd.init();
  // turn on LCD backlight                      
  lcd.backlight();
}

void loop(){
  // set cursor to first column, first row
  lcd.setCursor(0, 0);
  // print static message
  lcd.print(messageStatic);
  // print scrolling message
  scrollText(1, messageToScroll, 250, lcdColumns);
}

After reading the previous section, you should be familiar on how this sketch works, so we’ll just take a look at the newly created function: scrollText()

void scrollText(int row, String message, int delayTime, int lcdColumns) {
  for (int i=0; i < lcdColumns; i++) {
    message = " " + message; 
  } 
  message = message + " "; 
  for (int pos = 0; pos < message.length(); pos++) {
    lcd.setCursor(0, row);
    lcd.print(message.substring(pos, pos + lcdColumns));
    delay(delayTime);
  }
}

To use this function you should pass four arguments:

  • row: row number where the text will be display
  • message: message to scroll
  • delayTime: delay between each character shifting. Higher delay times will result in slower text shifting, and lower delay times will result in faster text shifting.
  • lcdColumns: number of columns of your LCD

In our code, here’s how we use the scrollText() function:

scrollText(1, messageToScroll, 250, lcdColumns);

The messageToScroll variable is displayed in the second row (1 corresponds to the second row), with a delay time of 250 ms (the GIF image is speed up 1.5x).

Display Custom Characters

In a 16×2 LCD there are 32 blocks where you can display characters. Each block is made out of 5×8 tiny pixels. You can display custom characters by defining the state of each tiny pixel. For that, you can create a byte variable to hold  the state of each pixel.

To create your custom character, you can go here to generate the byte variable for your character. For example, a heart:

Copy the byte variable to your code (before the setup()). You can call it heart:

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

Then, in the setup(), create a custom character using the createChar() function. This function accepts as arguments a location to allocate the char and the char variable as follows:

lcd.createChar(0, heart);

Then, in the loop(), set the cursor to where you want the character to be displayed:

lcd.setCursor(0, 0);

Use the write() method to display the character. Pass the location where the character is allocated, as follows:

lcd.write(0);

Wrapping Up

In summary, in this tutorial we’ve shown you how to use an I2C LCD display with the ESP32/ESP8266 with Arduino IDE: how to display static text, scrolling text and custom characters. This tutorial also works with the Arduino board, you just need to change the pin assignment to use the Arduino I2C pins.

We have other tutorials with ESP32 that you may find useful:

Thanks for reading.

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Published by Gnd_To_Vcc

Here to spread my knowledge . Knowledge should always be spread not stored.

One thought on “How to Use I2C LCD with ESP32 on Arduino IDE (ESP8266 compatible)

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