In this lesson, you will learn how to wire up and use an alphanumeric LCD display

The display has an LED backlight and can display two rows with up to 16 characters on each row. You can see the rectangles for each character on the display and the pixels that make up each character. The display is just white on blue and is intended for showing text. In this lesson, we will run the Arduino example program for the LCD library

Component Required:

  • 1 x Uno R3

  • 1 x LCD1602 module

  • 1 x Potentiometer (10k)

  • 1 x 830 tie-points Breadboard

  • 16 x M-M wires (Male to Male jumper wires)


Introduction to the pins of LCD1602:

VSS: A pin that connects to ground

VDD: A pin that connects to a +5V power supply

VO: A pin that adjust the contrast of LCD1602

RS: A register select pin that controls where in the LCD’s memory you are writing data to. You can select either the data register, which holds what goes on the screen, or an instruction register, which is where the LCD’s controller looks for instructions on what to do next.

R/W: A Read/Write pin that selects reading mode or writing mode

E: An enabling pin that, when supplied with low-level energy, causes the LDC module to execute relevant instructions.

D0-D7:Pins that read and write data

A and K: Pins that control the LED backlight

Connection Diagram:

Wiring schematic:

Physical Wiring Diagram:

The LCD display needs six Arduino pins, all set to be digital outputs. It also needs 5V and GND connections. There are a number of connections to be made. Lining up the display with the top of the breadboard helps to identify its pins without too much counting, especially if the breadboard has its rows numbered with row 1 as the top row of the board. Do not forget, the long yellow lead that links the slider of the pot to pin 3 of the display. The 'pot' is used to control the contrast of the display. You may find that your display is supplied without header pins attached to it. If so, follow the instructions in the next section.


After wiring, you need to install the relevant library file <LiquidCrystal.h> listed below:

  LiquidCrystal Library - Hello World

 Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
 library works with all LCD displays that are compatible with the
 Hitachi HD44780 driver. There are many of them out there, and you
 can usually tell them by the 16-pin interface.

 This sketch prints "Hello World!" to the LCD
 and shows the time.

  The circuit:
 * LCD RS pin to digital pin 7
 * LCD Enable pin to digital pin 8
 * LCD D4 pin to digital pin 9
 * LCD D5 pin to digital pin 10
 * LCD D6 pin to digital pin 11
 * LCD D7 pin to digital pin 12
 * LCD R/W pin to ground
 * LCD VSS pin to ground
 * LCD VCC pin to 5V
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)

 Library originally added 18 Apr 2008
 by David A. Mellis
 library modified 5 Jul 2009
 by Limor Fried (
 example added 9 Jul 2009
 by Tom Igoe
 modified 22 Nov 2010
 by Tom Igoe

 This example code is in the public domain.

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Hello, World!");

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis() / 1000);

Code Explained

The first thing of note in the sketch is the line:

#include <LiquidCrystal.h>

This tells Arduino that we wish to use the Liquid Crystal library.

Next we have the line that we had to modify. This defines which pins of the Arduino are to be connected to which pins of the display.

LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

After uploading this code, make sure the backlight is lit up, and adjust the potentiometer all the way around until you see the text message.

In the 'setup' function, we have two commands:

lcd.begin(16, 2); lcd.print("Hello, World!");

The first tells the Liquid Crystal library how many columns and rows the display has.

The second line displays the message that we see on the first line of the screen.

In the 'loop' function, we also have two commands:

lcd.setCursor(0, 1); lcd.print(millis()/1000);

The first sets the cursor position (where the next text will appear) to column 0 & row 1. Both column and row numbers start at 0 rather than 1. The second line displays the number of milliseconds since the Arduino was reset.

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