Arduino Membrane Keypad Tutorial

A keypad allows you to interact with a microcontroller. You can salvage these keypads from old telephones or you can purchase them from most electronics store for less than $2.

They come in wide variety of shapes and sizes. The most commons sizes are 3×4 and 4×4 and you can get keypads with with words, letters and numbers written on the keys.

You can even create your own keypad from scratch.

If you follow this tutorial you can control any keypad.

Description

These keypads very popular among the Arduino tinkerers. They are very cheap and you can use them with any microcontroller (MCU).

Where to buy?

You can purchase these modules for just a few dollars. Click here to compare the membrane keypad on several stores and find the best price.

You can use the preceding links or go directly to MakerAdvisor.com/tools to find all the parts for your projects at the best price!

How it Works?

A membrane keypad is a matrix consisting of rows and columns. Each key is assigned to a certain row and column (see the picture below).

On a 12 button keypad you have 4 rows and 3 columns. The first key would make a link between Row 1 and Column 1 (R1C1). 2 would be R1C2, 3 R1C3, *  R4C1, 9 R3C3 and so on.

Arduino with Membrane Keypad

You need the following components to make this circuit:

• 1x Arduino (eBay)
• 1x Keypad (eBay)
• Jumper Wires

Schematics

Follow the next schematics. If your keypad is different from the one below, try to search for the datasheet online.

Library Download

Here’s the library you need for this project:

1. Download the Keypad library
2. Unzip the Keypad library
3. Install the Keypad library in your Arduino IDE by moving the unzipped folder to: Arduino\Libraries
4. Restart your Arduino IDE

Uploading the Code

If your keypad doesn’t work with code below you might have to change the connections from the previous schematics.

Search the web or go to the store that sold you the keypad to find the datasheet for your keypad.

Note: If your keypad has more keys you can change lines 3 and 4 to add the right number of rows and columns. Then in line 5 you can change the array to match your keypad keys.

#include "Keypad.h"
 
const byte ROWS = 4; // number of rows
const byte COLS = 3; // number of columns
char keys[ROWS][COLS] = {
{'1','2','3'},
{'4','5','6'},
{'7','8','9'},
{'#','0','*'}
};

byte rowPins[ROWS] = {8, 7, 6, 5}; // row pinouts of the keypad R1 = D8, R2 = D7, R3 = D6, R4 = D5
byte colPins[COLS] = {4, 3, 2};    // column pinouts of the keypad C1 = D4, C2 = D3, C3 = D2
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
 
void setup()
{
  Serial.begin(9600);
}
 
void loop()
{
  char key = keypad.getKey(); 
  if (key != NO_KEY)
    Serial.println(key);
}

View raw code

Demonstration

In this project when you press a key, it’s displayed the value in your serial montior. Here’s what you should see in your Arduino IDE serial monitor when you start pressing the keypad keys.