Test code

 #include <Servo.h>

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

// Initialize I2C LCD (Try 0x3F if 0x27 doesn't work)

LiquidCrystal_I2C lcd(0x27, 16, 2);

Servo barrierServo;

// Pin Definitions matching your wiring

const int irSensorPin = 2; // IR Obstacle Sensor OUT

const int switchPin = 3; // Manual Override Push Switch

const int greenLedPin = 4; // Green Status LED

const int redLedPin = 5; // Red Status LED

const int servoPin = 6; // Servo Motor PWM Signal

const int buzzerPin = 8; // Active Buzzer

void setup() {

  // Initialize Serial Monitor for debugging

  Serial.begin(9600);

  // Configure Pin Modes

  pinMode(irSensorPin, INPUT);

  pinMode(switchPin, INPUT_PULLUP); // Internal pull-up resistor enabled

  pinMode(greenLedPin, OUTPUT);

  pinMode(redLedPin, OUTPUT);

  pinMode(buzzerPin, OUTPUT);

  // Attach Servo and set initial closed position (0 degrees)

  barrierServo.attach(servoPin);

  barrierServo.write(0);

  // Default state: Red LED ON (Gate Closed)

  digitalWrite(redLedPin, HIGH);

  digitalWrite(greenLedPin, LOW);

  // Initialize LCD Display

  lcd.init();

  lcd.backlight();

  

  lcd.setCursor(0, 0);

  lcd.print("Smart Toll System");

  lcd.setCursor(0, 1);

  lcd.print("Testing All Parts");

  

  // Startup beep

  tone(buzzerPin, 1000, 300);

  delay(2000);

  lcd.clear();

}

void loop() {

  // Read sensor and switch states

  int irState = digitalRead(irSensorPin); // Usually LOW when an object is detected

  int switchState = digitalRead(switchPin); // LOW when button is pressed

  // Print live diagnostics to Serial Monitor (Tools -> Serial Monitor)

  Serial.print("IR Sensor: ");

  Serial.print(irState);

  Serial.print(" | Switch: ");

  Serial.println(switchState);

  // Trigger condition: IR detects car (LOW) OR Manual switch is pressed (LOW)

  if (irState == LOW || switchState == LOW) {

    // 1. Audio and Visual Alert

    tone(buzzerPin, 1200, 200);

    digitalWrite(redLedPin, LOW);

    digitalWrite(greenLedPin, HIGH);

    // 2. LCD Feedback

    lcd.setCursor(0, 0);

    lcd.print("Car Detected! ");

    lcd.setCursor(0, 1);

    lcd.print("Opening Gate... ");

    // 3. Open Servo Gate (90 degrees)

    barrierServo.write(90);

    delay(4000); // Keep gate open for 4 seconds

    // 4. Closing Warning Sequence

    tone(buzzerPin, 800, 300);

    lcd.setCursor(0, 0);

    lcd.print("Gate Closing... ");

    lcd.setCursor(0, 1);

    lcd.print("Please Wait ");

    

    // Close Servo Gate (0 degrees)

    barrierServo.write(0);

    digitalWrite(greenLedPin, LOW);

    digitalWrite(redLedPin, HIGH);

    

    delay(1000);

    lcd.clear();

  } 

  else {

    // Idle / Ready State

    digitalWrite(redLedPin, HIGH);

    digitalWrite(greenLedPin, LOW);

    

    lcd.setCursor(0, 0);

    lcd.print("Slot Available ");

    lcd.setCursor(0, 1);

    lcd.print("Wai

ting for Car ");

  }

  delay(100); // Small debounce delay

}