#define Trig_PIN 12 // Pin connect to Trig pin
#define Echo_PIN 13 // Pin connect to Echo pin
#define LED_PIN 11 // Pin connect to LED (Active HIGH) ** Use PIN 11, 10, 9, 6, 5 or 3 only **

void setup() {
  pinMode(Trig_PIN, OUTPUT);
  pinMode(Echo_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);

  Serial.begin(9600);
}

void loop() {
  // Read distance from HC-04
  digitalWrite(Trig_PIN, LOW);
  delayMicroseconds(5);
  digitalWrite(Trig_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(Trig_PIN, LOW);
  unsigned int PulseWidth = pulseIn(Echo_PIN, HIGH);
  unsigned int distance = PulseWidth * 0.0173681;

  Serial.print("Distance is ");
  Serial.print(distance);
  Serial.println(" cm.");
  // -------------------------

  int val = map(distance, 2, min(10, distance), 80, 255); // resize distance form 1 - 10 to 80 - 255
  analogWrite(LED_PIN, val); // Set brightness of LED

  delay(100);
}