Arduino Sketch for Plastic Bottle and Can Reverse Vending Machine

This Reverse Vending Machine (RVM) project automatically identifies, segregates, and records plastic bottles and aluminum cans. It uses multiple sensors for detection and verification, servo motors for sorting, and wireless communication (GSM/WiFi) for data reporting.

Project Overview

The system integrates:

Arduino UNO – Main controller
Ultrasonic Sensors (HC-SR04) – Object distance & insertion detection
Load Cell with HX711 module – Weight verification
Inductive Sensor – Metal can detection
Photoelectric Sensor – Object presence detection
Micro Servo Motors (SG90/MG90S) – Sorting gate control
GSM Module (SIM800/SIM900) – SMS/data communication
WiFi Module (ESP8266) – Cloud data transmission
16x2 LCD Display – User interface
Relay/Driver Circuits – Actuator control

Working Principle

Object Insertion Detection
- Photoelectric sensor detects item entry.
- Ultrasonic sensor confirms object position.
Material Identification
- Inductive sensor detects metal (aluminum cans).
- If not metal, the system checks weight using load cell to confirm plastic bottle.
Sorting Mechanism
- Servo motor rotates gate:
  - Metal → Can compartment
  - Plastic → Bottle compartment
Weight Recording
- Load cell measures item weight.
- Data logged for reward calculation.
Data Communication
- Sends transaction data via GSM SMS or WiFi to cloud/server.
- Tracks total items collected.
User Interface
- LCD displays:
  - “Insert Item”
  - Item Type (Can/Bottle)
  - Weight
  - Points Earned
  - Thank You Message

Key Features

Automatic plastic and metal segregation
Accurate weight-based validation
Dual communication (GSM + WiFi)
Real-time LCD feedback
Smart recycling reward-ready system
Scalable for public recycling stations

Code:

/*
 * Arduino Sketch for Plastic Bottle and Can Reverse Vending Machine
 * This code interfaces with various sensors and actuators to segregate
 * plastic bottles and cans, and provides WiFi access for data transmission.
 * Components used:
 * - Ultrasonic Sensors for distance measurement
 * - Load Cell for weight measurement
 * - Micro Servos for actuation
 * - GSM Module for communication
 * - LCD Display for user interface
 * - Inductive and Photoelectric Sensors for object detection
 */

#include <Servo.h>
#include <HX711.h>
#include <LiquidCrystal.h>

// Pin definitions
#define TRIG_PIN1 5
#define ECHO_PIN1 6
#define TRIG_PIN2 7
#define ECHO_PIN2 8
#define SERVO_PIN1 9
#define SERVO_PIN2 10
#define SERVO_PIN3 11
#define SERVO_PIN4 12
#define LOAD_CELL_DOUT_PIN 13
#define LOAD_CELL_SCK_PIN 14
#define INDUCTIVE_SENSOR_PIN 2
#define PHOTOELECTRIC_SENSOR_PIN 16
#define GSM_TX_PIN 3
#define GSM_RX_PIN 18
#define LCD_RS_PIN 17
#define LCD_E_PIN 18
#define LCD_DB4_PIN 19
#define LCD_DB5_PIN 20
#define LCD_DB6_PIN 21
#define LCD_DB7_PIN 22

// Servo objects
Servo servo1;
Servo servo2;
Servo servo3;
Servo servo4;

// Load Cell object
HX711 scale;

// LCD object
LiquidCrystal lcd(LCD_RS_PIN, LCD_E_PIN, LCD_DB4_PIN, LCD_DB5_PIN, LCD_DB6_PIN, LCD_DB7_PIN);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Initialize ultrasonic sensors
  pinMode(TRIG_PIN1, OUTPUT);
  pinMode(ECHO_PIN1, INPUT);
  pinMode(TRIG_PIN2, OUTPUT);
  pinMode(ECHO_PIN2, INPUT);

  // Initialize servos
  servo1.attach(SERVO_PIN1);
  servo2.attach(SERVO_PIN2);
  servo3.attach(SERVO_PIN3);
  servo4.attach(SERVO_PIN4);

  // Initialize load cell
  scale.begin(LOAD_CELL_DOUT_PIN, LOAD_CELL_SCK_PIN);

  // Initialize LCD
  lcd.begin(16, 2);
  lcd.print("RVM System");

  // Initialize sensors
  pinMode(INDUCTIVE_SENSOR_PIN, INPUT);
  pinMode(PHOTOELECTRIC_SENSOR_PIN, INPUT);
}

void loop() {
  // Measure distance with ultrasonic sensor 1
  long duration1, distance1;
  digitalWrite(TRIG_PIN1, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN1, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN1, LOW);
  duration1 = pulseIn(ECHO_PIN1, HIGH);
  distance1 = (duration1 / 2) / 29.1;

  // Measure distance with ultrasonic sensor 2
  long duration2, distance2;
  digitalWrite(TRIG_PIN2, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN2, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN2, LOW);
  duration2 = pulseIn(ECHO_PIN2, HIGH);
  distance2 = (duration2 / 2) / 29.1;

  // Read load cell value
  float weight = scale.get_units(10);

  // Read inductive sensor value
  int inductiveValue = digitalRead(INDUCTIVE_SENSOR_PIN);

  // Read photoelectric sensor value
  int photoelectricValue = digitalRead(PHOTOELECTRIC_SENSOR_PIN);

  // Display values on LCD
  lcd.setCursor(0, 1);
  lcd.print("Dist1:");
  lcd.print(distance1);
  lcd.print("cm ");
  lcd.print("Dist2:");
  lcd.print(distance2);
  lcd.print("cm");

  // Actuate servos based on sensor values
  if (inductiveValue == HIGH) {
    servo1.write(90);
  } else {
    servo1.write(0);
  }

  if (photoelectricValue == HIGH) {
    servo2.write(90);
  } else {
    servo2.write(0);
  }

  if (weight > 100) {
    servo3.write(90);
  } else {
    servo3.write(0);
  }

  delay(1000);
}

Applications

Smart recycling stations
IoT-based waste management systems
College & public recycling projects
Smart city initiatives
Environmental sustainability automation

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