This code uses an ultrasonic sensor and buzzer to measure distance. It defines the trigger and echo pins for the ultrasonic sensor and the buzzer pin. In setup, it initializes the pins and Serial communication. In loop, it uses the ultrasonic sensor to measure distance, sounds the buzzer for distances between 10-30cm, and prints the distance to Serial.

1. Jawaher.A.Fadhil
Ultrasonic With Buzzer
int buzzer = 8 ;
// Ultrasonic 4 pins
#define trigPin 12
// or (const int trigPin = 12;)
#define echoPin 13
void setup()
{
Serial.begin (9600);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode (buzzer, OUTPUT) ;
}
void loop()
{
int duration, distance;
digitalWrite(trigPin, HIGH);
//delay(1000);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
// speed=distance/time; speed of sound through air is = 29.1
distance = (duration/2) / 29.1;
if (distance >= 200 || distance <= 0)
{
Serial.println("Out of range");
noTone( buzzer );
}
else {
if (distance >= 10&& distance <=30 )
{tone( buzzer, 200 );
delayMicroseconds(10);
//delay(10);
//Serial.print(distance);
//Serial.println(" cm");
tone( buzzer, 200 );
//delayMicroseconds(10);
delay(300);
}
Serial.print(distance);
Serial.println(" cm");
noTone( buzzer );
delay(100);
}}