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

#define IR_SENSOR1 2  // First IR sensor
#define IR_SENSOR2 3  // Second IR sensor
#define BUZZER 9      // Buzzer pin

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address (0x27 or 0x3F), 16x2 LCD

// Distance between IR sensors (in cm)
const float sensor_distance = 10.0;
unsigned long start_time, end_time;
float speed; 

void setup() {
    pinMode(IR_SENSOR1, INPUT);
    pinMode(IR_SENSOR2, INPUT);
    pinMode(BUZZER, OUTPUT);

    lcd.init();
    lcd.backlight();
    lcd.setCursor(0, 0);
    lcd.print("Speed Detection");
    delay(2000);
    lcd.clear();
}

void loop() {
    if (digitalRead(IR_SENSOR1) == LOW) { // First sensor triggered
        start_time = millis(); // Start time
        while (digitalRead(IR_SENSOR2) == HIGH); // Wait for second sensor
        end_time = millis(); // End time

        float time_taken = (end_time - start_time) / 1000.0; // Convert to seconds
        speed = (sensor_distance / time_taken) * 0.036; // Convert to km/h

        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Speed: ");
        lcd.print(speed);
        lcd.print(" km/h");

        if (speed > 40.0) {  // Speed limit (adjustable)
            digitalWrite(BUZZER, HIGH);
            lcd.setCursor(0, 1);
            lcd.print("Over Speed!");
            delay(2000);
            digitalWrite(BUZZER, LOW);
        }
        delay(2000);
    }
}