Proximity Alarm Distance Meter

// proximity sensor
// Tgst hassan shettima lawan contact me on;
// hassanshettima705@gmail.com +2347062769748 +2348183555452



const int buzzerPin = 8;               // buzzzer signal pin attached to digital pin 8
const int trigPin = 11;               // ultrasonic triggerPin connected to digital pin 11
const int echoPin = 10;               // ultrasonic echoPin connected to digital pin 10
int ledPin = 13;                      // LED positive connecteed to digital pin 13 (no need for resistor)
long duration;
float distanceMeters, distanceCm, distanceInch;

void setup() {                        // define all digital and analog pins
  pinMode(13, OUTPUT);                // LED pin as output
  pinMode(trigPin, OUTPUT);           // trigger pin as output because it sends signal
  pinMode(8, OUTPUT);                 // buzzer pin as output
  pinMode(echoPin, INPUT);             // echo pin as input becaue it recievs signals
  Serial.begin(9600);                  // initiate serial communication
}

void loop() {
  digitalWrite(trigPin, HIGH);                // initiate the ultrasonic sensor for sending and receiving
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  distanceMeters = duration * 0.00034 / 2;      // speed of sound per second; divide by 2 due to then sound coming back to the echo part of the sensor
  distanceCm = duration * 0.034 / 2;
  distanceInch = duration * 0.0133 / 2;

  Serial.print("Distance: ");                     // print distance (meters) in serial monitor
  Serial.print(distanceMeters);
  Serial.println("  Meters");
  delay(300);

  Serial.print("Distance: ");                      // print distance (centi meters) in serial monitor
  Serial.print(distanceCm);
  Serial.println("  cm");
  delay(300);

  Serial.print("Distance: ");                        // print distance (inches) in serial monitor
  Serial.print(distanceInch);
  Serial.println("  inch");
  delay(300);
  Serial.println("----------------------------");     // seoeration


  if (distanceCm <= 30 )    {                           // if distance is greater than or equal to 30 cm on LED and on buzzer ON and OFF
    digitalWrite(13, HIGH);                                 // ...... with delay as interval
    tone(buzzerPin, 1200);
    delay(500);                                                 //   u can tweak the code to suit yourn needs
    noTone(buzzerPin);
    digitalWrite(13, LOW);
    delay(5);
  }
  else if (distanceCm > 100 )    {
    digitalWrite(13, LOW);
    noTone(buzzerPin);
  }
}