Smart IoT Bin

Abstract

Key Features

Components Required

• 🎛️
  Arduino Uno Main microcontroller — processes sensor data and controls all peripherals
• 📡
  HC-SR04 Ultrasonic Sensor ×2 One for proximity detection (lid trigger), one for waste-level measurement
• ⚙️
  SG90 Servo Motor Controls the automatic lid — opens and closes based on proximity
• 📟
  I2C LCD 16×2 Displays current fill level and system status
• 📱
  SIM800L GSM Module Sends SMS alerts when bin is full — requires a SIM card with data plan
• 🔋
  Power Supply 5V USB or battery pack — note that SIM800L requires stable 3.7–4.2V at up to 2A

How It Works

1. The proximity ultrasonic sensor (Sensor 1) continuously scans for objects within a set range (e.g. 20 cm).
2. When a person approaches the bin, the servo motor rotates to open the lid automatically.
3. After a configurable delay (e.g. 3 seconds) with no proximity detected, the servo closes the lid.
4. The waste-level ultrasonic sensor (Sensor 2) measures the distance from the top of the bin to the waste surface.
5. The system calculates the fill percentage: fill% = (1 - distance / bin_height) × 100.
6. The fill percentage is displayed on the I2C LCD in real time (e.g. "Fill Level: 72%").
7. When fill level exceeds the threshold (default 80%), the SIM800L sends an SMS alert to the configured number.
8. The alert message includes the bin ID and fill level, e.g. "BIN FULL: Bin-01 at 85%. Please empty."

Live Browser Demo

This browser simulation replicates the Smart Bin's behaviour. Use the controls to simulate waste being added or removed, and watch the system respond with lid actions and GSM alerts.

The following is the core Arduino sketch. Install the LiquidCrystal_I2C and Servo libraries before uploading.

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

LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo lidServo;
SoftwareSerial gsm(10, 11); // RX, TX for SIM800L

// Pin definitions
const int TRIG_PROX  = 3;  // Proximity sensor TRIG
const int ECHO_PROX  = 4;  // Proximity sensor ECHO
const int TRIG_LEVEL = 5;  // Level sensor TRIG
const int ECHO_LEVEL = 6;  // Level sensor ECHO
const int SERVO_PIN  = 9;  // Servo motor

const float BIN_HEIGHT_CM   = 30.0; // Physical bin height
const float PROX_THRESHOLD  = 20.0; // cm — lid trigger distance
const int   ALERT_THRESHOLD = 80;   // % — SMS alert level
const int   LID_OPEN_MS     = 3000; // lid hold-open duration

bool alertSent = false;

long measureDistance(int trigPin, int echoPin) {
    digitalWrite(trigPin, LOW); delayMicroseconds(2);
    digitalWrite(trigPin, HIGH); delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    long duration = pulseIn(echoPin, HIGH, 30000);
    return duration * 0.034 / 2;
}

void sendSMS(String msg) {
    gsm.println("AT+CMGF=1");
    delay(500);
    gsm.println("AT+CMGS=\"+91XXXXXXXXXX\""); // Replace with number
    delay(500);
    gsm.print(msg);
    gsm.write(26); // Ctrl+Z
    delay(2000);
}

void setup() {
    lcd.init(); lcd.backlight();
    lidServo.attach(SERVO_PIN);
    lidServo.write(0); // Closed
    pinMode(TRIG_PROX, OUTPUT); pinMode(ECHO_PROX, INPUT);
    pinMode(TRIG_LEVEL, OUTPUT); pinMode(ECHO_LEVEL, INPUT);
    gsm.begin(9600);
    lcd.setCursor(0, 0); lcd.print("Smart IoT Bin");
    lcd.setCursor(0, 1); lcd.print("Initialising...");
    delay(2000); lcd.clear();
}

void loop() {
    long proxDist = measureDistance(TRIG_PROX, ECHO_PROX);
    if (proxDist < PROX_THRESHOLD) {
        lidServo.write(90); // Open lid
        delay(LID_OPEN_MS);
        lidServo.write(0);  // Close lid
    }

    long levelDist  = measureDistance(TRIG_LEVEL, ECHO_LEVEL);
    int  fillPercent = max(0, min(100, (int)((1.0 - (float)levelDist / BIN_HEIGHT_CM) * 100)));

    lcd.setCursor(0, 0); lcd.print("Fill Level:     ");
    lcd.setCursor(0, 1); lcd.print(String(fillPercent) + "%           ");

    if (fillPercent >= ALERT_THRESHOLD && !alertSent) {
        sendSMS("BIN FULL: Bin-01 at " + String(fillPercent) + "%. Please empty.");
        alertSent = true;
    }

    if (fillPercent < 20) alertSent = false;

    delay(1000);
}
                    

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