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

LiquidCrystal_I2C lcd(0x27, 16, 2);


// ICR(INT1_vect){
  
// }

float read_adc() {
  ADCSRA |= (1 << ADSC);                    // Start the Conversion
  while (ADCSRA & (1 << ADSC));             // Wait for Conversion to Complete
  uint16_t adcValue = ADC;                  // Read the ADC Value
  float voltage = adcValue / (1023 / 5.00);
  return voltage;
}

volatile float voltage = 0.0;

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

void setup() {
    PORTD = 1 << PD2;  // ? //interal pull up
    lcd.init();
    lcd.backlight();
    voltage = read_adc();
    print_voltage();
}

int main() {
    init();
    setup();
    while(true) {
      float new_voltage = read_adc();
      // print_voltage();
      if (new_voltage != voltage) {
        voltage = new_voltage;
        print_voltage();
      }

    }
}