This is a keypad lock that can be used to relay to an actual lock/motor. The keypad itself can also be swapped out for a different form of verification. This is more of a concept project meant for learning and not an actual product that should be used as a lock.


  1. Input a 4-digit code.
  2. The program checks whether the code matches the passcode after it’s reached 4 digits.
  3. If it does match then access is granted and it sends out a logic 1 out to a green LED or if it’s denied it sends it to the red LED.

what i learned

  1. How keypads work and how to take input from them
  2. How to use an I2C (pronounced I squared C) LCD Display.



I had to use a different LCD display that had a built in chip into the back so it only needed 4 pins instead of a regular one with 16 pins. I also had to figure out how keypads work and how to use them. With some very intense research (googling), I found libraries that suit my needs for this project. One of the guides showcased the same project but didn’t show any code so I had to figure that out on my own. All in all, it was a pretty easy project but now I know how to use keypads and an I2C LCD Display for my future projects. In the future, I hope to use the same locking concept but instead using an RFID receiver and tags.



Access Denied

Access Granted