#define echoPin 2              
#define trigPin 4
#define BUZINA 22

long duration, distance;
int temp = 340;
void setup(){

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode (BUZINA, OUTPUT);
  pinMode(2, OUTPUT);
 
  Serial.begin(9600);      
  Serial.println("SUCESSO");

  digitalWrite(2, HIGH);
  delay(2000);
  digitalWrite(2, LOW);
  
}
void loop(){
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  duration = pulseIn(echoPin, HIGH);
  distance = duration * temp/2 * 0.0001;

  Serial.print("Distance (cm): ");
  Serial.println(distance);
  delay(1000);

if (distance<20)
    {
    Serial.println("PROXIMO DEMAIS");
    tone(BUZINA,2000);
    delay(200);
    noTone(BUZINA);
    delay(50);
    }
    else {
    digitalWrite(BUZINA, HIGH);
    tone(BUZINA,2000);
    delay(500);
    digitalWrite(BUZINA, LOW);
    noTone(BUZINA);
    delay(500);      
    }
}