#include <LiquidCrystal_I2C.h>
#include <avr/interrupt.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // Adjust address to your LCD

volatile uint16_t adcValue = 0;             //uint16_t – 16-bit unsigned integer    Initialized at 0;
volatile bool conversionComplete = false;   //bool – initialize as false
volatile float lastVoltage = -1.0;          //Stores the last measured voltage value.     
volatile float voltage = 0.0;               //Initializes voltage variable at 0.0V

void print_voltage(){           //Function to print Voltage
  lcd.clear();                //Clear the lcd
  lcd.print(voltage);         //Print value held in voltage
  lcd.print(" V");            //Print " V" after voltage value
}

void setup() {                        //void setup() - function to Initialize the LCD, configure the ADC, and starts first ADC conversion
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);

  // Initialize ADC
  ADCSRA = 0xCF;    //This line does the same thing as the above lines

  sei(); // Enable global interrupts
}

ISR(ADC_vect) {
  adcValue = ADC; // Read the ADC value
  conversionComplete = true; // Set the conversion complete flag
}

void startConversion() {
  ADCSRA |= 0x40;
}

void loop() {
  if (conversionComplete) {
    voltage = adcValue * (5.0 / 1023.0); // Convert ADC value to voltage
    
    if (voltage != lastVoltage) { // Update the display only if the voltage has changed
      lastVoltage = voltage;
      print_voltage();
    }
    
    startConversion(); // Start a new conversion
  }
}