3x4 Matrix Keypad

It's a 3x4 numeric type keypad. The far-left and far-right pins are not used, leaving pins 1 to 7, starting from the left, for use.

You can check the pin numbers in the image provided.

[For example, pressing '1' on the keypad will output signals from pins 3 and 2.]

Specifications

Operating Voltage: 3 ~ 5V
Resistance: 10 ~ 150 ohms

Example Required Hardware

Arduino board
Jumper cables
3x4 keypad

Library

Keypad by Mark Stanley, Alexander Brevig (installable via the Library Manager)
Please refer to the Arduino library link for instructions on how to use the library.

Connection

keypad		Arduino
1		D7
2		D5
3		D8
4		D2
5		D6
6		D3
7		D4

example code

This code outputs to the serial monitor when a key on the keypad is pressed.

#include <Keypad.h>

const byte ROWS = 4;
const byte COLS = 3;

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

byte rowPins[ROWS] = { 5, 3, 4, 2 };
byte colPins[COLS] = { 8, 7, 6 };

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

void setup(){
  Serial.begin(9600);
  Serial.println("Serial start");
}

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

  if(key != NO_KEY){
      Serial.print(key);
  }
}

Execution Result