Published June 5, 2026

Touchless Doorbell V1

Busy with chores while welcoming guests? With this system, you won't need to stop what you're doing to welcome a guest in safely.

IntermediateShowcase (no instructions)Over 1 day36

Things used in this project

Hardware components

DFRobot I2C 16x2 Arduino LCD Display Module

Breadboard (generic)

Arduino Nano R3

SG90 Micro-servo motor

Seeed Studio Grove - Piezo Buzzer

Ultrasonic Sensor - HC-SR04 (Generic)

Machine Screw, M4

Ultra-High Molecular Weight Polyethylene Cord

Software apps and online services

Arduino IDE

Autodesk Tinkercad

Hand tools and fabrication machines

3D Printer (generic)

Story

This project was made for my Pre Engineering II Final Project, where the goal was to demonstrate what you've learned in this class. That includes wiring, coding, designing and many more aspects.

I had over a month come up with this project, I originally had no ideas and was really worried about getting this completed. One day in class, I began to look around the classroom, and my eyes set on the different door designs in the classroom and how they opened; from double doors to single doors. At that moment I realized I wanted to create a project that involved a door, but I didn't know exactly what it would be. The next day my teacher was running late from a coverage and the door was locked, standing outside for minutes I decided "what if there was a door operating system that could be used in emergencies, expecting guests, not being able to find your keys, or whatever the circumstance may be." Through those series of events I was able to come up with the idea of a Touchless Doorbell System.

My original idea for my project was to have the door open like a typical door, have hinges and move forward and backwards. I soon realized the faults with that design as I would need to double the size of the base in order to fit servo inside the base and the rest of my hardware, without the wiring getting tied up. Following that I decided to build a servo holder, and attach it to the left side of my base. This idea was primarily to create the "sliding door allusion" that is commonly seen with glass bath tub doors. While there wasn't any trouble opening the door, the trouble came with closing it, and questions amongst myself and my teacher began to surface due to the servo having insufficient power to close the door. Many of my designs had failed either before the 3D Print and after the 3D Print. Eventually I had decided to settle using a "Vertical lift mechanism" where gravity can aid the servo with closing the door. With this new mechanism, I originally wanted to use a string as a "belt" to open and close my door. After testing that idea, the design that I currently had wouldn't suffice, so instead I used one line of string and attached it to the servo head to open and close the door. My door also has supports similar to my original "sliding door" design to guide it in a straight path,

Overall the project uses an LCD monitor, Piezo buzzer, Servo, and Ultrasonic range finder. The Ultrasonic rage Finder is used as a motion detector outside of the base. If there is an object within 15 cm, the the system will activate. Along with that, I have an LCD monitor built into the base structure, to display messages. Once the system is activated, The LCD monitors text shifts from "System Ready" to "Doorbell Ringing." Once "Doorbell Ringing" is displayed, the Piezo Buzzer will sound as it is acting as the doorbell. Following these sequence of events, the LCD will shift its display again to "Door Opening", with the Servo rotating 180 degrees. After a few seconds the LCD will display "Door Closing" and the Servo will now rotate 180 degrees backwards. The end goal is to not only get a high grade on this final project because it's worth a lot, but to gain experience and properly prepare myself for engineering projects in the future, whether that be in college, graduate school, or even in the real world when I become an official engineer.

Wiring

Schematics

Code

Touchless Doorbell code

#include <Servo.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define TRIG 6
#define ECHO 7

#define BUZZER 9
#define SERVO_PIN 4

Servo doorServo;
LiquidCrystal_I2C lcd(0x27, 16, 2);

int getDistance() {
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  long d = pulseIn(ECHO, HIGH, 30000) * 0.034 / 2;
  return d;
}

bool detected() {
  int valid = 0;

  for (int i = 0; i < 5; i++) {
    int d = getDistance();
    if (d > 0 && d < 80) valid++;
    delay(50);
  }

  return valid >= 3;
}

void setup() {
  Serial.begin(9600);

  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(BUZZER, OUTPUT);

  doorServo.attach(SERVO_PIN);
  doorServo.write(0);

  lcd.init();
  lcd.backlight();
  lcd.print("System Ready");
}

void loop() {

  int d = getDistance();
  Serial.println(d);

  if (detected()) {

    tone(BUZZER, 1000);
    delay(300);
    noTone(BUZZER);

    lcd.clear();
    lcd.print("Doorbell Ringing");

    delay(1000);

    lcd.clear();
    lcd.print("Opening Door");

    doorServo.write(180);
    delay(5000);

    lcd.clear();
    lcd.print("Closing Door");

    doorServo.write(0);
    delay(3000);

    lcd.clear();
    lcd.print("System Ready");

    while (detected()) {
      delay(100);
    }
  }

  delay(150);
}