// Include the Ultrasonic library
#include <Ultrasonic.h>

// Define the pins for the ultrasonic sensor, LEDs, and buzzer
#define TRIGGER_PIN  11
#define ECHO_PIN     12
#define LED_PIN_1    7
#define LED_PIN_2    6
#define LED_PIN_3    5

// Create an Ultrasonic object
Ultrasonic ultrasonic(TRIGGER_PIN, ECHO_PIN);

// Define a variable to store the distance measured by the sensor
long distance;

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  
  // Set LED pins as output
  pinMode(LED_PIN_1, OUTPUT);
  pinMode(LED_PIN_2, OUTPUT);
  pinMode(LED_PIN_3, OUTPUT);
}

void loop() {
  // Measure the distance
  distance = ultrasonic.read();

  // Print the distance to the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Determine how many LEDs to turn on based on the distance
  if (distance < 7) {
    blinkLED(LED_PIN_1);  // Blink LED 1
    digitalWrite(LED_PIN_2, LOW);
    digitalWrite(LED_PIN_3, LOW);
  } else if (distance >= 7 && distance < 11) {
    blinkLED(LED_PIN_1);  // Blink LED 1
    blinkLED(LED_PIN_2);  // Blink LED 2
    digitalWrite(LED_PIN_3, LOW);
  } else {
    blinkLED(LED_PIN_1);  // Blink LED 1
    blinkLED(LED_PIN_2);  // Blink LED 2
    blinkLED(LED_PIN_3);  // Blink LED 3
  }

  // Wait for a short time before taking another measurement
  delay(500);
}

// Function to blink an LED
void blinkLED(int pin) {
  digitalWrite(pin, HIGH); // Turn on the LED
  delay(500);               // Wait for 500ms
  digitalWrite(pin, LOW);  // Turn off the LED
  delay(500);               // Wait for 500ms
}