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

// Set up a 20x4 LCD (address 0x27, update if different)
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Define analog pins for 4 photodiode modules
const int photodiodePins[4] = {A0, A1, A2, A3};

void setup() {
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("4 Photodiode Monitor");
  delay(2000);
}

void loop() {
  lcd.clear();

  for (int i = 0; i < 4; i++) {
    int rawValue = analogRead(photodiodePins[i]);
    int lightValue = 1023 - rawValue; // Invert so more light = higher number

    lcd.setCursor(0, i); // Line 0 to 3
    lcd.print("Sensor ");
    lcd.print(i + 1);
    lcd.print(": ");
    lcd.print(lightValue);
    lcd.print("    "); // Extra spaces to overwrite old digits
  }

  delay(500); // Update twice per second
}