sensore parcheggio finito

const int buzzer = 7;
const int echo = 8;
const int trig = 10;
const int led = 4;

long tempo;
int distanza;
int intervallo;
int freq;


void setup() {
  pinMode(led,OUTPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(echo,INPUT);
  pinMode(trig, OUTPUT);
  Serial.begin(9600);
}

void loop() {

  digitalWrite(trig,LOW);
  delayMicroseconds(5);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig,LOW);


  tempo=pulseIn(echo,HIGH);
  distanza=(tempo*0.034)/2;
  Serial.print("distanza:");
  Serial.print(distanza);
  Serial.println("cm   ");
  delay(300);

  intervallo=map(distanza, 5 , 40 , 20 , 500);
  freq=map(distanza, 5 , 40 , 880 , 220);

  if( distanza<5){
    tone(buzzer,440,200);
    digitalWrite(led,HIGH);
    delay(0);

  }
  else if(distanza>40){
    noTone(buzzer);
    digitalWrite(led, LOW);
  }
  if(  (distanza>=3 && distanza<=40) ){

   tone(buzzer,freq,50);
   delay(intervallo);
   tone(buzzer,freq,50);
   digitalWrite(led,HIGH);
   delay(intervallo);
   digitalWrite(led,LOW);
  }
  else{
    noTone(buzzer);
    digitalWrite(led,LOW);
  }
  return 0;






}