long duration;
int distance;
int ledBrightness;
const int trig = D5;
const int echo = D7;
const int led =  D4;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
  pinMode(led, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);

  duration = pulseIn(echo, HIGH);
  distance = (0.034 *  duration)/2;
  
  Serial.println(distance);
  ledBrightness = 400-distance;
  analogWrite(led,ledBrightness);
}