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

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


volatile uint16_t adcValue = 0;
volatile bool conversionComplete = false;
volatile float lastVoltage = -1.0;
volatile float voltage = 0.0;

void print_voltage(){
  lcd.clear();
  lcd.print(voltage);
  lcd.print(" V");
}

void setup() {
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  // lcd.print("Voltage: ");

  // Initialize ADC
  ADMUX = (1 << REFS0); // Reference Voltage: AVcc, Input Channel: ADC0
  ADCSRA = (1 << ADEN) | (1 << ADIE) | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // Enable ADC, Enable Interrupt, Prescaler: 128
  
  sei(); // Enable global interrupts
  
  startConversion(); // Start the first conversion
  voltage = adcValue * (5.0 / 1023.0); // Convert ADC value to voltage
  print_voltage();

}

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

void startConversion() {
  ADCSRA |= (1 << ADSC); // Start the ADC conversion
}

void loop() {
  if (conversionComplete) {
    conversionComplete = false; // Reset the flag
    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
  }
}