#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// set the LCD addres to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

int ldrPin = A0;     // LDR pin
int ldrVal = 0;      // Value of LDR
int ledPin = 2;     // Build in LED pin
// LDR Characteristics
const float GAMMA = 0.7;
const float RL10 = 50;
float lux;

void setup() {
  lcd.init();
  lcd.backlight();
  lcd.print("Welcome to T4T");
  lcd.setCursor(0,1);
  lcd.print("WORKSHOP!");
  delay(2000);
  Serial.begin(9600);  // Initialise the serial monitor
   pinMode(2, OUTPUT);
}
void loop() {
  lcd.clear();
  ldrVal = analogRead(ldrPin); // Read the analog value of the LDR
   float voltage = ldrVal / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

 if (lux < 200) {             // If the LDR value is lower than 200
      digitalWrite(ledPin, HIGH);   // Turn buildin LED on
      lcd.clear();
      lcd.setCursor(0,0);
      lcd.print("Light dey ON");
      lcd.setCursor(0,1);
      lcd.print("Lux data:");
      lcd.print(lux);
  } else {
    digitalWrite(ledPin, LOW);    // Turn buildin LED off
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("Light done OFF");
    lcd.setCursor(0,1);
    lcd.print("Lux data:");
    lcd.print(lux);
  }
  Serial.println(lux);      // Show the value in the serial monitor
  delay(1000);                 // Pause 1000ms
}