#include <Arduino.h>

const int trigPin = 12;   // Pin connected to the trigger pin of the sensor
const int echoPin = 13;   // Pin connected to the echo pin of the sensor
const int ledPin = 2;     // Pin connected to the LED

void setup() {
  Serial.begin(9600);     // Initialize serial communication
    pinMode(trigPin, OUTPUT);// Set the trigger pin as output
      pinMode(echoPin, INPUT); // Set the echo pin as input
        pinMode(ledPin, OUTPUT); // Set the LED pin as output
        }

        void loop() {
          long duration, distance; // Define variables for duration and distance

            // Clear the trigger pin
              digitalWrite(trigPin, LOW);
                delayMicroseconds(2);

                  // Send a pulse to trigger the sensor
                    digitalWrite(trigPin, HIGH);
                      delayMicroseconds(10);
                        digitalWrite(trigPin, LOW);

                          // Measure the duration of the pulse on the echo pin
                            duration = pulseIn(echoPin, HIGH);

                              // Calculate the distance
                                distance = duration * 0.034 / 2;

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

                                          // If the distance is between 4 and 30 cm, turn on the LED, otherwise turn it off
                                            if (distance >= 4 && distance <= 30) {
                                                digitalWrite(ledPin, HIGH);   // Turn on the LED
                                                  } else {
                                                      digitalWrite(ledPin, LOW);    // Turn off the LED
                                                        }

                                                          delay(1000); // Wait for a second before taking the next measurement
                                                          }