int DISTANCIA = 0;
int pinLed = 4;
int pinEco = 12;
int pinGatillo = 13;

int readUltrasonicDistance(int triggerPin, int echoPin) {
  pinMode(triggerPin, OUTPUT);
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);

  int duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;
  return distance;
}

void setup() {
  Serial.begin(115200);
  pinMode(pinLed, OUTPUT);
}

void loop() {
  DISTANCIA = 0.01723 * readUltrasonicDistance(pinGatillo, pinEco);
  Serial.println(DISTANCIA);
  
  if (DISTANCIA < 20) {
    digitalWrite(pinLed, HIGH);
  } else {
    digitalWrite(pinLed, LOW);
  }
  
  delay(10);
}