#define ECHO_PIN 2
#define TRIG_PIN 3
#define ledPin 5

long duration;
float distance;

void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(ledPin, OUTPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.1716;
  if (distance > 600 && distance< 800) {
    analogWrite(ledPin, distance-150);
  }
  else{
    analogWrite(ledPin, 0);
  }

  return distance;
}

void loop() {
  Serial.print("Measured distance: ");
  Serial.println(readDistanceCM());

  delay(100);
}