#define TRIG_PIN 10
#define ECHO_PIN 9


const int LED_R = 2;
const int LED_V = 3;
const int LED_B = 4;


void setup() {

  pinMode(LED_R, OUTPUT);
  pinMode(LED_V, OUTPUT);
  pinMode(LED_B, OUTPUT);

  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  digitalWrite(TRIG_PIN, LOW);
}

void loop() {
  // start lettura sensore
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  // lettura della ripsposta del sensore
  unsigned long tempo = pulseIn(ECHO_PIN, HIGH);
  // calcolo della distanza in cm
  float distanza = 0.03438 * tempo / 2;
  Serial.println("distanza = " + String(distanza) + " cm");
  delay(500);


  if (distanza < 15){
    digitalWrite(LED_R, HIGH);
    digitalWrite(LED_V, LOW),
    digitalWrite(LED_B, LOW);
    
   }
    else if(distanza > 15, distanza < 25 )  {  
    digitalWrite(LED_R, HIGH);
    digitalWrite(LED_V, HIGH);
    digitalWrite(LED_B, LOW);
    
  
  }
  

  else if (distanza > 25) {
    digitalWrite(LED_R, LOW);
    digitalWrite(LED_V, HIGH);
    digitalWrite(LED_B, LOW);
    
  }

  else if(distanza < 6) { 
    digitalWrite(LED_R, LOW);
    digitalWrite(LED_V, LOW);
    digitalWrite(LED_B, LOW);
    
 }
}