This document describes a smart door knocker device that uses an Arduino, piezoelectric sensor, servo motor, and other components. The piezoelectric sensor detects knock signals which are processed by the Arduino microcontroller. The microcontroller then actuates the servo motor to unlock the door if the knock signal matches a programmed pattern, allowing authorized users to enter. The document outlines the components, wiring diagrams, programming process, and some troubleshooting for the smart door knocker system.

1. Instrumentation:
Smart Door
Knocker
Authorized by:
Berlin Richad Simanjuntak
Dinda Eka Pratiwi
Rifqi Nugraha
2A-Refrigeration and Air
Conditioning
Polytechnic State of
Bandung

2. Source:
http://www.instructables.com/id/Secret-Knock-Detecting-
Door-Lock/
with title:
Secret Knock Detecting Door Lock

3. The Equipments
 1. Arduino UNO R3
 2. Servo
 3. LED
 4. Resistors
 5. Buzzer
 6. Piezoelectric
 7. Push Button
 8. Cable for jumper
 9. Protoboard
 10. PCB

4. Original Wiring

5. Wiring with Modification

6. Process
Piezoelectric
receive a knock
signal
The Signal
received by
microcontroller
The microcontroller
processed the
actuator

7. Software and Program

8.  If we want to control the arduino, we must
input the program by using software Arduino
IDE. First we should adapt the COM of the
Arduino with our software. Then, we should
choose the same board between the Arduino
and the software (example: Board Arduino
Genuino Uno, COM 11).

9. The trouble when making “Smart
Door Knocker”
 1. To adjust the signal input into the
piezoelectric in order to compare with
frequency of a knock.
 2. The function of push button sometimes
didn’t work.

10. For more info, visit: