const float conv1 = 0.7;
const float conv2 = 50;

void setup() {
  // put your setup code here, to run once:
pinMode(9, OUTPUT);
Serial.begin(9600);
}

void loop() {

int valorAnalogo = analogRead(A0);
float voltage = valorAnalogo / 1024. * 5;
float resistencia = 2000 * voltage / (1 - voltage / 5);
float lux = pow(conv2 * 1e3 * pow(10, conv1) / resistencia, (1 / conv1));


  if (lux >= 0 && lux <512)
  {
    analogWrite(9,255);
  }
  if (lux >= 512 && lux <= 1024)
  {
    analogWrite(9,64);
  }

  Serial.println(lux);
}