In this project, learners explore how technology can improve cleanliness and waste management using sensors and the Arduino Uno R4 WiFi. They build a smart dustbin that opens automatically and tracks usage, learning key ideas in automation and smart city systems. We have included extra challenges that encourage learners to experiment with sensor placement and features, making learning fun and hands-on. Through this experience, learners develop creativity, problem-solving skills, and environmental responsibility while discovering how smart technology promotes hygiene, convenience, and cleaner homes and schools.

Here’s how different components connect:

First Ultrasonic Sensor 

This sensor detects a person approaching the dustbin and opens the lid

• VCC → connects to the 5V on the Arduino

• GND → connects to the GND on the Arduino

• TRIG → connects to the digital Pin 2 on the Arduino

• ECHO → connects to the digital Pin 3 on the Arduino

Second Ultrasonic Sensor

This sensor is placed inside the dustbin, facing downwards and detects when the bin is full.

• VCC → connects to the 5V on the Arduino

• GND → connects to the GND on the Arduino

• TRIG → connects to the digital Pin 4 on the Arduino

• ECHO → connects to the digital Pin 5 on the Arduino

The Servo Motor

Servo motor open and close the Dustbin lid

• Red wire of servo → connects to the 5V on the Arduino

• Brown/Black wire of the servo → connects to the GND on the Arduino

• Yellow/Orange wire (signal) of the servo → connects to the digital Pin 9 on the Arduino

Green LED

Indicates Bin Not Full

• Connect the long leg (positive/anode) of the LED to one end of the 220Ω resistor

• Connect the other end of the resistor to digital pin 7 on the Arduino.

• Connect the short leg (negative/cathode) of the LED to GND.

Red LED

Indicates the When the Bin is full

• Connect the long leg (positive/anode) of the LED to one end of the 220Ω resistor

• Connect the other end of the resistor to digital pin 8 on the Arduino.

• Connect the short leg (negative/cathode) of the LED to GND.

The Buzzer

Sound the Alarm when the bin is full

• Connect the positive (+) pin of the buzzer to digital pin 6 on the Arduino.

• Connect the negative (–) pin of the buzzer to GND on the Arduino

Open the Arduino IDE on your computer and type this code:

#include

Servo lidServo;

// Pins
int trigPerson = 2;
int echoPerson = 3;

int trigBin = 4;
int echoBin = 5;

int servoPin = 9;
int greenLED = 7;
int redLED = 8;
int buzzer = 6;

long duration;
int distancePerson;
int distanceBin;

void setup() {
pinMode(trigPerson, OUTPUT);
pinMode(echoPerson, INPUT);
pinMode(trigBin, OUTPUT);
pinMode(echoBin, INPUT);

pinMode(greenLED, OUTPUT);
pinMode(redLED, OUTPUT);
pinMode(buzzer, OUTPUT);

lidServo.attach(servoPin);
lidServo.write(0); // Lid closed
}

void loop() {
// Person detection
distancePerson = getDistance(trigPerson, echoPerson);
if (distancePerson < 20) {
lidServo.write(90); // Open lid
delay(2000);
lidServo.write(0); // Close lid
}

// Bin level detection
distanceBin = getDistance(trigBin, echoBin);
if (distanceBin < 10) { // Bin full
digitalWrite(redLED, HIGH);
digitalWrite(greenLED, LOW);
digitalWrite(buzzer, HIGH);
} else { // Bin not full
digitalWrite(greenLED, HIGH);
digitalWrite(redLED, LOW);
digitalWrite(buzzer, LOW);
}

delay(500);
}

int getDistance(int trigPin, int echoPin) {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin, HIGH);
return duration * 0.034 / 2;
}

1. Connect your Arduino Uno to your computer using the USB cable
2. In the Arduino IDE, go to:

• Tools → Board → Arduino Uno
• Tools → Port → (Select your Arduino port)

3. Click the Upload button (the right arrow icon).
4. Watch your project come to life!

• Servo not moving

  • Check power connections

  • Confirm correct servo pin

• Lid opens randomly

  • Adjust distance threshold of the first ultrasonic sensor

• Bin always shows full

  • Move internal sensor higher

  • Increase distanceBin threshold

• Buzzer too loud

  • Reduce buzzer active time

• How automatic systems reduce human contact

• How sensors measure distance

• How servo motors create movement

• How smart bins support hygiene and recycling

• Real-world smart city and environmental concepts

• Add an LCD screen showing “Bin Full”

• Count how many times the bin is used

• Send bin status to a phone using WiFi

• Add color-coded bins (plastic, paper, metal)

• Build a real bin model using cardboard or plastic