Arduino 16×2 LCD Interfacing Tutorial

This is a comprehensive guide for Arduino LCD (Liquid Crystal Display) Interfacing. You’ll learn how to use 16×2 LCD with Arduino and create some example projects to practice what we’ll be learning in this tutorial. We’ll implement the following examples in this tutorial:

• Arduino 16×2 LCD Text Display
• Arduino 16×2 LCD Variables Display
• Arduino 16×2 LCD Scrolling Text
• Arduino 16×2 LCD Custom Characters Display

We’ll start off by explaining how LCD works, its pinout, and how to connect it to your Arduino board. We’ll display some text and numbers on the LCD screen, make the text scroll on the LCD, and also create some custom characters and emojis. Without further ado, let’s get right into it!

Table of Contents

1. 16×2 Liquid Crystal Display (LCD) – Alphanumeric
2. 16×2 LCD Pinout
3. Connecting Arduino to 16×2 LCD (Wiring Diagram)
4. Arduino LCD Contrast Adjustment
5. Arduino 16×2 LCD Code Example
6. Arduino 16×2 LCD Display Variables Example
7. Arduino LCD Scrolling Text Example
8. Arduino LCD Custom Character Generation & Display
9. Arduino LiquidCrystal Library Useful Function
10. Arduino 16×2 LCD Common Issues Troubleshooting
11. Wrap Up

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16×2 Liquid Crystal Display (LCD) – Alphanumeric

LCD (Liquid Crystal Display) is typically used in embedded systems to display text and numbers for the end user as an output device. The 16×2 alphanumeric display is based on the Hitachi HD44780 driver IC. Which is the small black circular chip on the back of the LCD module itself. This is the controller that controls the LCD unit and we communicate with using Arduino to send commands and text messages.

The LCD module consists of 16×2 character cells (2 rows x 16 columns), each cell of which is 5×8 dots. Controlling all of these individual dots is a tedious task for our Arduino. However, it doesn’t have to do so. As there is a specific function controller on the LCD itself controlling the display while reading the user’s commands & data (the Hitachi HD44780 controller).

The simplest way to communicate with the Hitachi HD44780 LCD driver is to use the Arduino LiquidCrystal library to handle this communication. This is going to provide us with an easy way to perform different operations with the LCD display without getting into the details of the LCD driver itself. However, if you want to learn more about the HD44780 LCD driver and how the LCD works on a low level, you can check this tutorial.

Alphanumeric LCDs are available in different units with different sizes (e.g. 16×1, 16×2, 16×4, 20×4, and so on). The backlight color of the LCD display is also available in multiple variants (green, yellow, blue, white, and red).

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16×2 LCD Pinout

This is the pinout for a typical LCD 16×2 display unit. It’s got 8 data lines (you can use only 4 of them or all of the 8). And keep in mind that it needs to be powered from a stable +5v source.

GND is the ground pin.

Vcc is the LCD’s power supply input pin (connects to +5v).

Vo (Contrast Control) is the LCD contrast control pin. We typically use a voltage divider network to establish the control voltage that sets the desired contrast level or simply use a potentiometer to have a controllable contrast level for the LCD display.

RS is the register select pin whose function is to separate the data (text and numbers) from the commands to LCD (like set cursor position, clear LCD display, shift text, etc).

RW is the Read/Write pin. Which determines the type of operation we’ll be doing with the LCD (read or write). As we’re typically using the LCD for displaying output data, it’s rarely set in read mode and this pin is usually held LOW to operate in the WRITE mode.

EN is the enable pin. The enable signal is required for the parallel communication interface of the LCD in order to latch in the incoming data. An enable short pulse is required for the completion of each data transfer operation.

D0-D7 (Data Pins) are the data bus pins (8-bit). The LCD can operate in 4-bit bus mode which means we can send each byte of data in two steps using the 4-bit mode. This will save us 4 IO pins that would have been wasted to create the full 8-pins bus.

LED+ (Anode) is the LCD’s backlight LED’s anode (+) pin. This pin connects to the +5v power supply through a current limiting resistor (220Ω or 330Ω).

LED- (Kathode) is the LCD’s backlight LED’s cathode (-) pin. This pin connects to the ground.

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Connecting Arduino to 16×2 LCD (Wiring Diagram)

Here is the wiring diagram for the 16×2 LCD display with Arduino that we’ll be using in all examples hereafter in this tutorial.

And here is a summary table for Arduino -> LCD connections.

Arduino UNO	16×2 LCD
2	D7
3	D6
4	D5
5	D4
11	EN
12	RS

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Arduino LCD Contrast Adjustment

Before attempting to program the LCD and start actually using it, we need first to test it on a hardware level and also set a proper level of display contrast. This can easily be done after connecting the LCD to Arduino’s +5v power, then using the potentiometer we can set the LCD contrast level as shown in the short demo video below.

If the LCD’s pixels are responding to the potentiometer change, this is a good sign that it should be working and you can proceed further to the Arduino code example projects in the next sections.

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Arduino 16×2 LCD Code Example

Now, let’s test what we’ve learned so far about the Arduino LCD and create our first project to display some text messages on the LCD display. On the first row of the LCD, we’ll print the “Hello World!” message. And we’ll move the cursor to the second row and write a “DeepBlueMbedded” text message.

Arduino LCD Text Display Example

In this first example, we’ll include the Arduino’s LiquidCrystal library and use it to display some text messages on the LCD 16×2 display.

Wiring

Here is how to hook up the LCD 16×2 display to the Arduino UNO board.

Example Code

Here is the full code listing for this example.

Code Explanation

First of all, we need to include the Arduino LiquidCrystal.h library which we’ll be using to control the LCD driver.

Next, we’ll create an object of the LiquidCrystal class and define its parameters. The parameters for the LiquidCrystal object are the pin numbers for the following signals: RS, EN, D4, D5, D5, D7. If you want to add another LCD, you’ll have to create another object with another 6 IO pins for its signals.

setup()

in the setup() function, we initialize the LCD object ( MyLCD) using the .begin() function. Which takes only 2 parameters (number of columns, and number of rows). For 16×2 LCD, we call MyLCD.begin(16, 2); For 20×4 LCD, we call MyLCD.begin(20, 4); And so on.

Then, we set the LCD cursor position to point to the first line, the first character cell. Any write operation to the LCD will start from the current cursor position value, that’s why it’s important to set it manually before attempting any write operation. This is to make sure that the text will be displayed exactly where we want it to be.

There are 2 rows and 16 columns in our LCD as we’ve stated earlier. The cursor index value starts from 0, therefore, the first row has an index of 0, and the second row has an index of 1. And this is also the case for the columns’ index value which also starts from 0 up to 15.

Next, we’ll print the first text message "Hello World!" to the LCD starting from the current cursor position (0, 0). Using the .print() function.

Similarly, we’ll point to the beginning of the second LCD line (row) and write the second message.

loop()

in the loop() function, nothing needs to be done.

Simulation

Here is the simulation result for this project on the TinkerCAD simulator.

You can check this simulation project on TinkerCAD using this link.

Testing Results

Here is the result of testing this project code example on my Arduino UNO board.

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Arduino 16×2 LCD Display Variables Example

In this example, we’ll print numeric variables to the LCD display. We’ll create a counter variable and print it to the LCD using the same .print() function. Which can also accept a lot of variable data types (strings, integers, float, double, etc). So luckily, we won’t be in need to do string manipulations and data type conversion to achieve the goals of this example project.

Wiring

Exactly the same as the previous example project.

Example Code

Here is the full code listing for this example.

Code Explanation

First of all, we need to include the Arduino LiquidCrystal.h library which we’ll be using to control the LCD driver.

Next, we’ll create an object of the LiquidCrystal class and define its parameters. The parameters for the LiquidCrystal object are the pin numbers for the following signals: RS, EN, D4, D5, D5, D7. If you want to add another LCD, you’ll have to create another object with another 6 IO pins for its signals.

setup()

in the setup() function, we initialize the LCD object ( MyLCD) using the .begin() function.

Then, we set the LCD cursor position to point to the first line, the first character cell. Any write operation to the LCD will start from the current cursor position value, that’s why it’s important to set it manually before attempting any write operation. To make sure that the text will be displayed exactly where we want it to be.

Next, we’ll print the first text message "Counter Value:" to the LCD starting from the current cursor position (0, 0). Using the .print() function.

loop()

in the loop() function, we’ll point to the first character location on the second row (line) of the LCD. And write the Counter variable to the LCD using the .print() function.

We also increment the Counter variable and insert a small time delay before repeating the same instructions over and over again.

Simulation

Here is the simulation result for this project on the TinkerCAD simulator.

You can check this simulation project on TinkerCAD using this link.

Testing Results

Here is the result of testing this project code example on my Arduino UNO board.

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Arduino LCD Scrolling Text Example

In this example, we’ll print some text messages and shift the entire LCD display to create a text-scrolling effect. We’ll use the scrollDisplayLeft() and scrollDisplayRight() functions to create the scrolling effect.

Wiring

Exactly the same as the previous example project.

Example Code

Here is the full code listing for this example.

Code Explanation

First of all, we need to include the Arduino LiquidCrystal.h library which we’ll be using to control the LCD driver.

Next, we’ll create an object of the LiquidCrystal class and define its parameters. The parameters for the LiquidCrystal object are the pin numbers for the following signals: RS, EN, D4, D5, D5, D7. If you want to add another LCD, you’ll have to create another object with another 6 IO pins for its signals.

setup()

in the setup() function, we initialize the LCD object ( MyLCD) using the .begin() function.

Then, we set the LCD cursor position to point to the first line, the first character cell. Any write operation to the LCD will start from the current cursor position value, that’s why it’s important to set it manually before attempting any write operation. To make sure that the text will be displayed exactly where we want it to be.

Next, we’ll print the first text messages " Arduino LCD " and “ DeepBlueMbedded” to the LCD on lines 1 and 2 respectively. Using the .print() function.

loop()

in the loop() function, we’ll shift the entire display to the right side 10 times using a for loop and the scrollDisplayRight() function from the LCD LiquidCrystal library. The inserted delay here is to allow us to see the scrolling effect, and you can definitely change it to make the scrolling effect even faster or slower.

Next, we’ll repeat the same step but the shifting will be in the opposite direction (left) and the code logic will be repeated forever.

Simulation

Here is the simulation result for this project on the TinkerCAD simulator.

You can check this simulation project on TinkerCAD using this link.

Testing Results

Here is the result for testing this project code example on my Arduino UNO board.

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Arduino LCD Custom Character Generation & Display

In this example project, we’ll create some custom characters (emojis and icons) and send them to the LCD display. It has an internal CGRAM that can hold up to 8 custom characters at maximum and you’ll learn how to use it in this example project.

Arduino LCD Custom Character Generator

You can use this online LCD Custom Character Generator Tool and it’ll give you the Arduino C-Code for it, which you can easily copy and paste into your project code. And here is how to use it:

Click on the pixels to draw your custom LCD character, you can invert or clear the entire display cell if you want with the buttons below. If you’re satisfied with how your icon/emoji looks, you can copy the code and you’re good to go. Here are some example custom characters generated by this tool.

I used my custom LCD character generator tool to create the above icons/emojis (heart, speaker, smiley face, notification bell, battery level indicator). We’ll display all of those icons in this example project to show you how it’s done in Arduino code.

Wiring

Exactly the same as the previous example projects.

Example Code

Here is the full code listing for this example.

Code Explanation

First of all, we need to include the Arduino LiquidCrystal.h library which we’ll be using to control the LCD driver.

Next, we’ll create an object of the LiquidCrystal class and define its parameters. The parameters for the LiquidCrystal object are the pin numbers for the following signals: RS, EN, D4, D5, D5, D7. If you want to add another LCD, you’ll have to create another object with another 6 IO pins for its signals.

We’ll also define the byte array for the 8 custom characters that we’ve previously generated using the online tool.

setup()

in the setup() function, we initialize the LCD object ( MyLCD) using the .begin() function.

Then, we send the 8 custom characters byte-arrays to the LCD to be stored in its CGRAM memory.

Next, we’ll clear the entire LCD display screen before writing. This step also moves the cursor to the home position (0, 0).

And finally, we’ll print the LCD custom characters. This is not a usual print command, it’s a command for the LCD to print the custom character saved in a specific location in the CGRAM memory. The following line of code tells the LCD to print the custom character saved in the CGRAM address location 0.

And similarly, we’ll do the same for the rest of the custom characters saved in the CGRAM address location 0 up to 7.

loop()

in the loop() function, nothing needs to be done.

Simulation

Here is the simulation result for this project on the TinkerCAD simulator.

You can check this simulation project on TinkerCAD using this link.

Testing Results

Here is the result of testing this project code example on my Arduino UNO board.

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Arduino LiquidCrystal Library Useful Function

Here is a summarized list for the most important and useful functions in the LCD LiquidCrystal.h library that you’d need to use in your Arduino projects.

LiquidCrystal Library Function	Function Description
lcd.begin(cols, rows);	Initializes the interface to the LCD screen, and specifies the dimensions (width and height) of the display. the .begin() function needs to be called before any other LCD library commands.
lcd.clear();	Clears the LCD screen and points the cursor to the home position (in the upper-left corner).
lcd.home();	Sets the cursor to the home position (in the upper-left of the LCD) without clearing the text on the display.
lcd.setCursor(col, row);	Position the LCD cursor to a desired location.
lcd.noCursor();	Hides the LCD cursor.
lcd.cursor();	Display the LCD cursor if it has been hidden.
lcd.blink();	Display the blinking LCD cursor. If used in combination with the cursor() function, the result will depend on the particular display device.
lcd.noBlink();	Turns off the blinking LCD cursor.
lcd.noDisplay();	Turns off the LCD display, without losing the text currently shown on it. This can be done to save some power if needed.
lcd.display();	Turns on the LCD display, after it’s been turned off with the noDisplay() function. This will restore the text (and cursor) that was on the display.
lcd.scrollDisplayLeft();	Scrolls the contents of the display (text and cursor) one space to the left.
lcd.scrollDisplayRight();	Scrolls the contents of the display (text and cursor) one space to the right.
lcd.autoscroll();	Turns on automatic scrolling of the LCD. This causes each character output to the display to push previous characters over by one space. If the current text direction is left-to-right (the default), the display scrolls to the left; if the current direction is right-to-left, the display scrolls to the right. This has the effect of outputting each new character to the same location on the LCD.
lcd.noAutoscroll();	Turns off the automatic scrolling feature of the LCD.
lcd.leftToRight();	Set the direction for text written to the LCD to left-to-right, the default. This means that subsequent characters written to the display will go from left to right, but does not affect previously-output text.
lcd.rightToLeft();	Set the direction for text written to the LCD to right-to-left (the default is left-to-right). This means that subsequent characters written to the display will go from right to left, but does not affect previously-output text.

You can also refer to Arduino’s official LiquidCrystal library page for more information and examples of the available APIs (functions) in this library.

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Arduino 16×2 LCD Common Issues Troubleshooting

In this section, we’ll discuss some of the most common Arduino 16×2 LCD interfacing issues and how to troubleshoot those issues if you’re facing any of them in your project.

Garbage Characters Display

If your LCD is displaying garbage characters, it’s a strong indicator that there is an issue with data communication between your Arduino board and the LCD module itself. Make sure your connections are correct and the pin numbers for wiring are matching the software configurations that you’ve set in code like this.

LCD Showing Black Boxes or Blank Display

This can be a contrast issue at the Vo pin, so make sure you’re connecting the contrast control potentiometer and turn it to the right and left until it’s properly set to an acceptable level.

Contrast is Ok, But Still Blank Display

This can be a power supply issue, make sure you’re connected to a stable +5v power supply. Sometimes powering from a USB port in a computer can cause power issues like this, so try using a power bank or a proper power supply and check if the issue is still persistent.

Using a poor power supply USB port, poor quality USB cables or even USB extender cables can cause all sorts of power issues. And the LCD display module is sensitive to such issues that you’d not detect during LEDs and buttons example projects.

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Wrap Up

To conclude this tutorial, we can say that the Arduino LiquidCrystal library eases the process of interfacing Arduino with LCD 16×2 display modules. You can even use it with different sizes of LCD displays like 16×4 or 20×4. This tutorial is a fundamental part of our Arduino Series of Tutorials because we’ll use it in so many tutorials and projects hereafter. So make sure, you’ve learned all the concepts and implemented the practice examples whether on your Arduino board or at least in the simulation environment.

If you’re just getting started with Arduino, you need to check out the Arduino Getting Started [Ultimate Guide] here.

And follow this Arduino Series of Tutorials to learn more about Arduino Programming.

It’s highly recommended to check out the Arduino I2C LCD interfacing tutorial linked below for more information about the I2C LCD module and how to use it with Arduino. There are so many examples right there which will definitely help you get the hang of it.

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