Howto setup your first keypad

In this tutorial the assumption is that you have never used a keypad with your Arduino. Because of that I will make an attempt to cover everything you need to get it working.

Example

/* @file HelloKeypad.pde
 || @version 1.0
 || @author Alexander Brevig
 || @contact alexanderbrevig@gmail.com
 ||
 || @description
 || | Demonstrates the simplest use of the matrix Keypad library.
 || #
 */
#include <Keypad.h>

#define ledPin 13

// Connect keypad ROW0, ROW1, ROW2 and ROW3 to these pins, 
// eg. ROW0 = Arduino pin2.
byte rowPins[] = { 9, 8, 7, 6 };

// Connect keypad COL0, COL1 and COL2 to these pins, 
// eg. COL0 = Arduino pin6.
byte colPins[] = { 12, 11, 10 };

//create a new Keypad
Keypad keypad = Keypad(rowPins, colPins, sizeof(rowPins), sizeof(colPins));

void setup()
{
  digitalWrite(ledPin, HIGH);
  Serial.begin(9600);
}

void loop()
{
  char key = keypad.getKey();

  if (key) {    // same as if(key != NO_KEY)
    Serial.println(key);
  }
}