/*
 Voltaat learn (https://www.voltaat.com)
 Link for full tutorial:
 Link for libraries:

 Send characters and numbers to your Arduino using a keypad

 The function of this sketch is to print data from the keypad to your computer through the serial monitor. You can develop this code to make more complex projects, such as a system with a secure password

 Connections from the keypad to Arduino:
 Pins on the keypad are numbered from 1 to 8
 • Keypad pin 1 → Arduino pin 2
 • Keypad pin 2 → Arduino pin 3
 • Keypad pin 3 → Arduino pin 4
 • Keypad pin 4 → Arduino pin 5
 • Keypad pin 5 → Arduino pin 6
 • Keypad pin 6 → Arduino pin 7
 • Keypad pin 7 → Arduino pin 8
 • Keypad pin 8 → Arduino pin 9

*/

// This library allows you to connect the keypad with arduino
#include "Keypad.h"
//Define variables (the four rows)
const int ROW_NUM = 4;
//Define variables (the four columns)
const int COLUMN_NUM = 4;

//Instantiates a Keypad object that uses pins 5, 4, 3, 2 as row pins, and 8, 7, 6 as column pins.
//This keypad has 4 rows and 3 columns, resulting in 12 keys.
char keys[ROW_NUM][COLUMN_NUM] = {
 {'1', '2', '3', 'A'},
 {'4', '5', '6', 'B'},
 {'7', '8', '9', 'C'},
 {'*', '0', '#', 'D'}
};

//Connect to the row pinouts of the keypad
byte pin_rows[ROW_NUM] = {9, 8, 7, 6};
//Connect to the column pinouts of the keypad
byte pin_column[COLUMN_NUM] = {5, 4, 3, 2};
Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );

//Commands inside void setup run once
void setup() {
 // Start the serial monitor at 9600 baud rate (9600 bits per second)
 Serial.begin(9600);
}

//Commands inside void loop run forever
void loop() {

 //Returns the key that is pressed
 char key = keypad.getKey();

 //If key is pressed
 if (key) {
   Serial.print(key);
   Serial.println(" Is pressed on your keypad");
 }
}