LCD Interfacing with Arduino UNO R3

lcd interfacing with arduino

In this tutorial, you will learn how to interface LCD with Arduino. We will be using Arduino Uno, but the same code and concepts work for other Arduino development boards also. Firstly, 16×2 LCD interfacing with Arduino will be discussed. After that, we will also provide examples of 16×4 LCD and I2C LCD interfacing with Arduino.

Why We need to Interface LCD with Arduino?

The first question that must come to your mind is that why we need to interface LCD with Arduino? There are many applications in embedded projects in which wants to display different types of data on LCD. For example, it is used to display different sensors data such as temperature, humidity, pressure, light intensity, voltage, current and many others. Hence, the use of liquid crystal displays is very popular and common in Arduino project. It is also recommended to learn LCD interfacing at the start. Because when you learn to interface sensors with Arduino, you will already have a coding experience to display that sensor value.

Liquid Crystal Display Introduction

As its name suggests LCDs are electronics devices that are used to display texts, custom characters, and numbers. Although, we can also display pictures on LCDs. But results will be not comparable to graphical LCDs (GLCDs). GLCDs are used to display images. Coming back to LCDs, they are available in different sizes and features. For example, 16×2, 20×2, 16×1 are different sizes available.

Types

They come in two types serial and parallel LCDs. Serial type uses serial communication, such as the UART module, to interface with Arduino. They are easier to interface with Arduino than parallel LCDs. But they are expensive. In contrast, parallel LCDs, for example, Hitachi HD44780, are exceptionally used and interfacing with Arduino is done using digital I/O pins of Arduino. For instance, Hitachi HD44780 type 16×2 LCD can be interfaced with Arduino using 4-8 data lines and few control pins of the display. In this tutorial, we will be using 16×2 parallel LCD only. Because it is the most popular choice among the Arduino community and embedded application developers.

16×2 LCD Introduction

16 x 2 LCD has sixteen columns and two rows. That means, it can display sixteen characters per row and it has two such rows. Similarly, 20×4 LCD has four rows and 20 columns. That means, it can display 20 characters per row.

Pinout Diagram

The diagram shows the pin configuration of 16×2 display. It has sixteen pins.

16X2 LCD Pinout diagram Pic Microcontroller tutorial

D0 – D7: Pin number 7-14 are data bus lines that are used to send data from Arduino which you want to display on LCD. With these 8 data lines, data can be transferred either in an 8-bit format or in a 4-bit format. In a 4-bit format, only upper four bits (D4-D7) are used to send data from Arduino to LCD. The full byte is transmitted in two successive transmissions. A 4-bit format is used to save GPIO pins of Arduino. Because fewer GPIO pins of Arduino will be required to transfer data.

Contrast Select (VEE): Pin3 will connect with power and ground through 3 pin potentiometers. It will help to control the contrast of PIXELS according to the 16X2 LCD light. 10K ohm variable resistor is connected with the VEE pin to adjust light contrast. Variable resistor one side is connected with 5 volts and the other side is connected with ground. The third terminal is connected with the VEE pin.

RS: This pin is known as a register select pin. It helps to toggle the command/data register.

R/W: The signal on Pin5 will decide whether it is going to read from LCD or write on it.

EN: Enable pin will help to transfer the instruction from the data pins and another command pin to the LCD. It act as permission to internal registers.

VSS: It’s a ground pin for common grounds.

VDD: The power pin will use for voltage input to the 16X2 LCD.

In Arduino, we don’t need to worry about controlling these data lines and control registers. Because Arduino provides rich library resources. LCD library comes with Arduino IDE by default when we install it.

Interfacing Schematic Diagram

This picture shows the connection diagram of Arduino with 16×2 LCD.

16x2 LCD Interfacing with Arduino connection diagram

If you are having to read connections according to above schematic, you can check this table for connections between Arduino and 16×2 LCD.

16X2 LCDArduino
D4 – D79, 10, 11, 12
E7
RS4
VEEPOT (Middle Leg)
VSSGround
VDD+5V
D++5V
D-Ground

Arduino LCD Library 

In this section, we will discuss different LCD control routines that are available in Arduino IDE. Most importantly, the same library function is used for all types of parallel LCDs such as 16×1, 16×2, 20×1, 20×4, etc. 

Firstly, we should include a header file. This header file contains prototypes and function definitions that are used to control display. 

#include <LiquidCrystal.h>

LCD Connections Declaration 

The second most important thing is the declaration of Arduino pins that are connected with LCD. To define connections, we use this line. This line created a “LiquidCrystal” object and “lcd” is a name of the object that we are going to use to call LCD functions. You can also use any other name.  

LiquidCrystal lcd(rs, en, d4, d5, d6, d7).

Lets say, we want to use any other name instead of LCD, we can define it like this:

LiquidCrystal myname(rs, en, d4, d5, d6, d7);

But now to call every you will use this name like myname.print(), myname.begin() etc. 

Here the first argument defines the connection of the RS pin of the LCD with the Arduino pin, the second argument is the EN pin, and so on. Let’s take an example. In this example, first, we give a name to each digital pin of Arduino. It will make the code easier to read and understand. 

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;

According to this declaration, you must connect RS pin of LCD to digital pin 12, En to 11 and so on. 

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

LCD Size 

Till now, we have defined the LCD connection and included its library. After that, we must define the size of the LCD. This lcd.begin() routine is used to define the size of an LCD. The first argument to this function is a number of rows and the second argument is a number of columns. For instance, this line declares the size as 16 columns and 2 rows. That means 16×2  size. 

lcd.begin(16, 2);

Similarly, we can specify the size according to the display we want to use. 

Now lets see a simple 16×2 LCD program to print text. This program prints “ABC” as shown in figure below. 

#include <LiquidCrystal.h>
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
void setup() 
{
  lcd.begin(16, 2);
  lcd.print("ABC");
}

void loop()
{
  // put your main code here, to run repeatedly:

}
LCD Interfacing with Arduino Hello word Program

As expected above code displays “ABC”. The lcd.print() function is used to send data. The most important thing to consider in this code is the position of the displayed text. As you can see from the figure, it starts printing text from the first location of LCD that is the first row and first column such as (0,0). Basically , lcd.print() start to display text from the current cursor position of LCD. Now let’s understand how to control and set cursor location.

LCD Cursor Setting

As you know that 16×2 LCD has 16 columns and two rows. One position can display only one ASCII character. Also, one location consists of one row and one column. For example, (0,0) means the first row and first column,  (0,1) means the first row and second column, and similarly, (1,0) means the second row and first column. This picture shows the position of each location according to rows and columns of 16×2 LCD.

16x2 LCD Cursor Position

Now the question that must come to your mind is that how to display ASCII characters on a specific location using lcd.print()? Fortunately, that’s very easy with Arduino. It can be done by controlling the cursor position using lcd.setCursor() function.

lcd.setCursor() function is used to set the location where we want to display character or text. The first argument to this function is a column number and the second argument is the row number. For example, this line sets the cursor position of the Arduino to the second row and first column. Because counting of rows and columns starts from zero.  

lcd.setCursor(0, 0); //set cursor to first column and first row
lcd.setCursor(15,0); //set cursor to 16th column and 2nd row
lcd.setCursor(0, 1); //set cursor to first column and 2nd row
lcd.setCursor(15, 1); //set cursor to 16th column and 2nd row

Now let’s see examples in order to understand LCD cursor position control with Arduino more clearly.

void loop()
{
  lcd.setCursor(6, 1);
  lcd.print(“ABC”);
}

This code provides the output as show in this figure. It displays “ABC” starting from 2nd row and 7th column position.

LCD cursor position control example arduino

Another most important feature to note in this code is that LCD cursor position automatically moves to the next position after displaying character on current position. In the above code, we set the cursor position to (1,6), but it also displays next characters such as ‘B’ and ‘C’ on the next location.

Visualize Cursor Position

Arduino library also provide function to visualize curson position. This code visualize advanced cursor position with underscore symbol.

void loop()
{
  lcd.setCursor(6, 1);
  lcd.print(“ABC”);
  lcd.cursor(); // this turns on cursor position by displaying underscore
}

The output of the above would be like this:

LCD cursor position display on Arduino

This auto cursor increment is very useful. Because we don’t have to set the cursor position again and again with the Arduino. Arduino will automatically display text to next the position. 

Arduino LCD Interfacing Example

As shown in the above circuit diagram, this circuit will display “BILAL MALIK” in the first row of LCD and “microcontrollers” in the second row of LCD. It is also shown in the above diagram, pin number 9-12 of Arduino UNO R3 is connected with LCD. you just have to write these pin numbers in LCD library functions arguments which tell Arduino that which pin of Arduino is connected with which pin of LCD. The code to display the above text which is showing on LCD is given below.

Arduino Sketch

// It inculde Liquid crystal display library in your code
 #include <LiquidCrystal.h>
 // This function assigns Arduino microcontroller about connection of LCD with Arduino. Pins should be connected in following manner :
 // LiquidCrystal(RS, EN, D4, D5, D6, D7)
 LiquidCrystal lcd(4, 7, 9, 10, 11, 12);

void setup()
{
 // following function set up the LCD columns and rows:
 lcd.begin(16, 2);
 }

void loop() {
 lcd.setCursor(0,0); // set the cursor position
 lcd.print("BILAL MALIK"); //print the string on cursor position
 lcd.setCursor(0,1);
 lcd.print("Microcontrollers");
 lcd.noDisplay(); // No display on LCD for 500ms
 delay(500);
 lcd.display();
 delay(500);
 }

Video Demo

Code is self-explanatory and we have also written comments along with each line of code. But if you still have any issue, let us know with your comments on this post.

Scrolling Text on LCD using Arduino

In the last section, we have learned to display simple text on LCD using Arduino. Now let’s move to some advanced examples. In this section, we will discuss examples of scrolling text on LCD. That means moving text towards left and right direction. 

Arduino LCD library supports two functions that are used to scroll text on LCD. These are routines are: 

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

As their name suggests, lcd.scrollDisplayRight(); moves the text one cursor position towards right from current text position and  lcd.scrollDisplayLeft(); moves the text one cursor position towards left. 

For example, in this picture LCD shows text “Micro Lab” on the 6th column and 1st row location.

Scrolling text on LCD Example using Arduino

Now if we call, lcd.scrollDisplayLeft(); function inside the code, it will move the text one position left and output will look like this: 

Scrolling text on LCD left scrolling example

Similarly, if we call lcd.scrollDisplayRight(), it will move the text one position right and output will look like this: 

Schematic Diagram 

Make connection with Arduino and 16×2 LCD according to this schematic diagram: 

Scrolling text on LCD using Arduin Schematic Diagam

Moving Text Arduino Code

Upload this code to Arduino IDE.

#include<LiquidCrystal.h>
LiquidCrystal lcd(12,11,5,4,3,2);
void setup() {
  lcd.begin(16,2);
  lcd.setCursor(5, 0);
  lcd.print("Micro Lab");
}

void loop() 
{  
  for(int i=0; i<5; i++)
  {
    lcd.scrollDisplayLeft();
    delay(600);
  }
  for(int i=0; i<5; i++)
 {
    lcd.scrollDisplayRight();
    delay(600);
  }

}

The output of code would be like this: 

Scrolling text on LCD Example using Arduino simulation

This code is quite similar to the last example except for the LCD scrolling part inside the loop() function. 

First, we set the cursor position to location (5,0) using cursor setting routine.

  lcd.setCursor(5, 0);

After that, it prints the text “Micro Lab” on the current cursor position. 

  lcd.print("Micro Lab");

As you know that if we call scrolling text left or right function of Arduino, they will move the text one one position towards left or right. Therefore, we used a loop to call these functions more than one time. 

First, we call  lcd.scrollDisplayLeft() 5 times using for loop iteration 5 times. Therefore, it moves the text towards left for 5 positions. 

 for(int i=0; i<5; i++)
{
    lcd.scrollDisplayLeft();
    delay(600);
  }

After that, we call  lcd.scrollDisplayRight() 5 times using for loop iteration 5 times. Therefore, it moves the text towards the right for 5 positions.

for(int i=0; i<5; i++)
{
    lcd.scrollDisplayRight();
    delay(600);
  }

Displaying Custom Characters on LCD using Arduino

In this section, we will learn to generate custom characters and learn to display custom characters on LCD using Arduino. Creating custom characters are useful when we want to display any symbol on LCD which is not available in the standard ASCII character set.

LCD Memory to store Custom Characters

As you know, the 16×2 LCD is based on the HD44780 controller. This controller has a butil-in character generation random access memory. CGRAM is used to display store user defined symbols or characters. Only 64 bytes of CGRAM is available. That means, due to limited memory, we can store a limited number of custom characters inside this memory. 

For example, a 16×2 LCD with 5×8 pixels for each position, only 8 custom characters can be stored and similarly for 5×10 pixel, type, only four can be stored. But still, this is enough memory. Because usually we need 1-2 user defined characters only such as battery. Sound, lock, bell symbol, etc.

Custom Characters Generation

Each location in the 16×2 LCD consists of 5×8 pixels. Therefore, to generate custom patterns, we must turn on and turn off individual dots according to the character that we want to display.

LCD 5x8 Pixels for custom character

To create custom symbols patterns, we can use an application available on this link

Go to the above link and make any user-defined character by setting or clearing specific pixels from the 5×8 grid of pixels. Let’s say, we want to make a bell icon. Select pixels according to this picture and you will see the pattern code will be generated. 

Custom pattern for Bell Icon LCD with Arduino

Similarly, you can generate as many user defined characters you want. But due to limited CGRAM, only 8 can be stored in the memory. 

To display custom characters, first we must generate code for each character and after that store this value inside the CGROM of 16×2 LCD.We can store our custom generated characters inside CGRAM and load them to display on LCD.

Storing Character Inside CGRAM with Arduino

In order to store these patterns inside CGRAM, Arduino IDE provides a createChar() function. The input argument to this function is a pattern ( array of bytes) and an address. The address will be from 0-7. For example, we generated a pattern for a bell icon that is

byte bel[] = {
  B00100,
  B01110,
  B01110,
  B01110,
  B01110,
  B11111,
  B00000,
  B00100
};

To store this, we call lcd.Create() function like this 

lcd.createChar(0, bell);

It will store the user-defined character bell on location ‘0’ in CGRAM. Now if you want to write this letter on LCD, you can use lcd.Write() like this:

lcd.Write(byte(0));

The important thing to note here is that we read character from the same location where lcd.Create() writes it. 

Custom Characters Generation Arduino Code

Upload this code to Arduino. It displays user-defined symbols such as lock, sound, heart and bell on 16×2 LCD.

#include<LiquidCrystal.h>
LiquidCrystal lcd(12,11,5,4,3,2);
byte lock[8] = { 
0b01110,
0b10001,
0b10001,
0b11111,
0b11011,
0b11011,
0b11111,
0b00000,};
byte sound[8] = {
0b00001,
0b00011,
0b00101,
0b01001,
0b01001,
0b01011,
0b11011,
0b11000} ; 
byte speaker[8] = {0b00001,
0b00011,
0b01111,
0b01111,
0b01111,
0b00011,
0b00001,
0b00000,}; 
byte heart[8] = {0b00000,
0b01010,
0b11111,
0b11111,
0b01110,
0b00100,
0b00000,
0b00000 }; 
void setup() {
  lcd.clear();
  lcd.begin(16,2);
  lcd.createChar(0,lock);
  lcd.setCursor(0,0);
  lcd.write(byte(0));
  delay(600);
  lcd.createChar(1,sound);
  lcd.setCursor(4,0);
  lcd.write(byte(1));
  delay(600);
  lcd.createChar(2,speaker);
  lcd.setCursor(8,0);
  lcd.write(byte(2));
  delay(600);
  lcd.createChar(3,heart);
  lcd.setCursor(12,0);
  lcd.write(byte(3));
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

The output of this code will look like this:

Displaying custom characters on LCD using Arduino Example

Write Serial Data on LCD using Arduino

This LCD interfacing example with Arduino demonstrates how to write serial data from Arduino serial monitor directly on 16×2 LCD.

#include<LiquidCrystal.h>
LiquidCrystal lcd(12,11,5,4,3,2);
byte ch;
int col=0;
int row=0;
void setup() {
  Serial.begin(9600);
  lcd.begin(16,2);
  lcd.clear();
  // put your setup code here, to run once:

}

void loop() {
  if(Serial.available()){
    char ch=Serial.read();
    Serial.write(ch);
    Serial.println();
    lcd.setCursor(col,row);
    lcd.write(ch);
    col++;
  
  if(col>15){
    row++;
    col=0;
    lcd.write(ch);
  }
  // put your main code here, to run repeatedly:

}
if(ch=='*' ||row==1&&col>=15){
  lcd.clear();
  col=0;
  row=0;
}
}

Video Demo

Applications

Liquid crystal display has many applications in embedded systems and digital electronics projects. Engineering students used LCDs in their projects to display various types of parameters. I have posted many articles on embedded system projects. In all these projects I have used liquid crystal display to display various physical parameters like temperature, analog current, analog voltage, humidity, the intensity of light, moisture and solar panel parameters. In all these projects, I have used LCD to display these parameters. You may also read following topics to get idea about applications of LCD.

1 thought on “LCD Interfacing with Arduino UNO R3”

  1. Respected sir,
    Hope u will be fine.. sir i need the complete diagrame and code of the GSM based electronic notice board using arduino with display.plz its my humble request that to send me this project thanks

    Reply

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