Arduino with a 3x4 Keypad

The following is something I made a while back with an Arduino, a speaker I ripped off from an old toy and two LEDs:



To make use of the keypad, I used Arduino's keypad library.

I connected the keypad to the Arduino as follows:

Keypad Pin	Arduino Pin
1	7
2	5
3	8
4	2
5	6
6	3
7	4

The above keypad numberings map as follows:

To use in your code, make sure you include it:

#include <Keypad.h>

You also need to map out the keys like such:

const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns

char keys[ROWS][COLS] = {
  {
    '1','2','3'    }
  ,
  {
    '4','5','6'    }
  ,
  {
    '7','8','9'    }
  ,
  {
    '*','0','#'    }
};

//The below numbers correspond to the Arduino Pins
byte rowPins[ROWS] = {5, 4, 3, 2}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {8, 7, 6};    //connect to the column pinouts of the keypad

Afterwards, instantiate the Keypad:

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

Then to get the key pressed, it's just as simple as this:

char key = keypad.getKey();