#include <Servo.h>

int ldrPin = A0;
int ldrVal = 0;
int ledPin = 2;
int relayPin = 3;
int servoPin = 11;
Servo myServo;

const float GAMMA = 0.7;
const float RL10 = 50;

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
  pinMode(relayPin, OUTPUT);
  myServo.attach(servoPin);
  myServo.write(0);
}

void loop() {
  ldrVal = analogRead(ldrPin);
  float voltage = ldrVal / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  if (lux > 200) {
    digitalWrite(ledPin, HIGH);
    digitalWrite(relayPin, HIGH);
    myServo.write(180);
  } else {
    digitalWrite(ledPin, LOW);
    digitalWrite(relayPin, LOW);
    myServo.write(0);
  }

  Serial.println(lux);
  delay(1000);
}