Introduction: ArdLock

This a door lock built as fun project.It is quite easy to build and a fun way to learn and improve your knowledge of arduino.I tried to add a 16*2 display but there werent enough GPIO pins on arduino Uno.If You are interested in adding a display you would need an arduino Mega.

Items Needed

Arduino UNO

Jumper wires

Servo(or anyother component to open a door lock like a linear actuauator)

Keypad(I used a 4*3 keypad)


Resistor(1k or 2k)


Get your Code

Get your code from-

Tip-You can use a 4*4 keypad too just by not using the last column.

Installing the library

Copy the keypad folder to Library folder under arduino folder(under>program files>arduino) .

Step 1: Connecting the Keypad to Arduino

At first you would like to connect a keypad and test if it is working flawlessly and to check your connections.

Connect your keypad through keypad pins to arduino pins 3 to 9(row pins to 3-6)(column pins to 7-9).You can verify your connections by seeing the color code of wires used.

Seeing the output

Use the Hello_keypad.ino code from the library to test for proper connections.(file>examples>Keypad(scrolldown)>hello_keypad)This code gives the button pressed on the serial monitor.

First you open the code in Arduino IDE and then upload it onto your arduino,then open the serialMonitor(button on the upper right corner).Then test by pressing a button and then observing the input on the serial monitor.

Tips for the main code

In the main code the previous character is deleted by pressing the * key.

Step 2: Building the Button

Do not remove the connections to the keypad while testing the button.

Our doorlock has a button to open or close a door from the inside.I built it using a pushbutton.As arduino reads voltages form a closed circuit we create a Circuit with a resistor.

The code to test if the button works is given in this segment.

Test the code before going forward.

Step 3: The Final Step

We finally connect both arduino and our button to control the door locking mechanism.Just upload the code with the previous circuit connections and see the magic.

Changing the key

To change the change the numbers as in the image in this step.

This is my first instructable and one of my first projects any suggestions are welcomed Thank you for going through the instructable. Have a good Day and have fun building it :D.



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    Sure it works with nano but needs some minor changes.

    Nice project can give me the circuit diagram for this project

    Nice project,

    You can always use a serial I2C LCD consuming only 2 extra I/Os of UNO, connecting that on SCL and SDA pins (or A4 and A5). The serial pins are located on upper left header, near ISP connector.

    1 reply

    Thank you, i will use this in my next instructable.

    una pregunta ¿donde esta para ver o descargar el código? por que no lo veo por ninguna parte.

    Thank You :D

    Hi Eswar,

    This is an Cool and Interesting DIY Kit... Hoping You are from India.. Can you please Add the Link to buy all the Items Required at any Online Website ! So that I can know about the Specifications?