#define LDR 15//define ldr pin
#define LED1 2//define led pin
#define LED2 4
#define LED3 16

//  ldr characteristic
const float gamma =0.7;
const float RL10= 50;

void setup() {
  // put your setup code here, to run once:
  pinMode(LDR, INPUT);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
  int analogValue= analogRead(LDR);//ldr analog output
  float voltage = analogValue /4096.*5;
  float resistance = 2000* voltage/ (1- voltage /5); 
  float lux= pow(RL10*1e3*pow(10,gamma) / resistance, (1 / gamma));

  Serial.println(lux);
  if (lux>2000){
    Serial.println("Light!");
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, LOW);
    digitalWrite(LED3, LOW);
  }else{
    Serial.println("Dark!");
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, HIGH);
    digitalWrite(LED3, HIGH);
  }
delay (1000);

}