Arduino Keypad Interfacing

In this tutorial, I am going to use a 4×4 keypad. It has sixteen buttons having four alphabetic characters. Let's have a look at the Arduino Keypad Interfacing:

What is Keypad?

• The keypad consists of multiple buttons, arranged in the form of a matrix(rows & columns) and is used in embedded projects.
• They are cost-efficient and are easily available from online electronic stores.
• Keypads are normally available in a 3×3, 4×3 and 4×4 format.
• Keypad has several applications in real life based projects e.g. mobile phones, calculators, laptops, personal computers, television remote, toy remote, microwave oven, photocopy machine, bank’s ATM machine, tablets and a lot more.
• A simple 4x4 Keypad is shown in the figure given below:

Keypad Pinout

• I am using a 4×4 keypad in this tutorial, it has total of eight (8) pins.
• All of these pins are provided in the table shown in the figure below:

• From the above table, we can see that keypad’s first four pins are associated with its four rows.
• The last four pins are assigned to the four columns of the keypad.
• 4×4 Keypad’s pins functions are listed in the table provided in the figure given below.

Components Required for Arduino Keypad Interfacing

• Components required for this project are:
  • Arduino UNO.
  • 4x4 Keypad.
  • Jumper Wires(Male to Female).

Keypad & Arduino Connections

• The connections between the keypad and Arduino are provided in the figure given below:

Circuit Diagram of Keypad Arduino Interfacing

• I have made a circuit diagram for keypad interfacing with Arduino.
• A complete labeled circuit diagram is given in the figure shown below:

• You can make a similar diagram and can easily test & verify your results on the serial monitor.

Arduino Code

• You just need to copy this code into your Arduino software.
• After successfully uploading the code to your Arduino board you will be able to verify the results.

#include <Keypad.h>

const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns
//define the cymbols on the buttons of the keypads
char hexaKeys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {5, 4, 3, 2}; //connect to the column pinouts of the keypad

//initialize an instance of class NewKeypad
Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS); 

void setup(){
  Serial.begin(9600);
}
  
void loop(){
  char customKey = customKeypad.getKey();
  
  if (customKey){
    Serial.println(customKey);
  }
}

• First of all, I have defined the number of rows and columns of the keypad.
• Then I have declared the complete keypad characters in terms of rows and columns.
• After that, I have defined the row and column pin of the keypad attached to the Arduino pins.
• Then I have simply read the data sent from the keypad and displayed it on the serial monitor.
• You can download a completely labeled wiring diagram and Arduino source code here by clicking on the below button:

In the tutorial Keypad Interfacing with Arduino, I have explained the basics of the keypad as well as the keypad interfacing with Arduino UNO. I have tried my level best to cover up all the necessary information. If you found something missing, please let me know then. I will update my tutorial correspondingly as soon as possible. I hope you have enjoyed the complete tutorial and I am hoping for your positive response. If you have any problem you can freely ask as in comments anytime. I will share different topics in my upcoming tutorials. Take care and bye till the next tutorial :)