#define FOSC 1843200 // Clock Speed
#define BAUD 9600
#define MYUBRR FOSC/16/BAUD-1
volatile uint16_t adcResult = 0;  // Variable to hold the ADC result

void setup() {
  Serial.begin(9600);           // Initialize Serial communication
  init_adc();                   // Initialize the ADC
  sei();                        // Enable global interrupts
}

void loop() {
  // The ADC value will be updated when the interrupt occurs
  Serial.print("ADC Value: ");
  Serial.println(adcResult);     // Print the ADC result
  delay(500);                   // Add a delay for readability
}

void init_adc() {
  ADMUX = 0x40;                 // Reference: AVCC, Input Channel: ADC0
  ADCSRA = 0x87;                // Enable ADC, Prescaler: 128
  ADCSRA |= (1 << ADIE);        // Enable ADC interrupt
  ADCSRA |= (1 << ADEN);        // Enable the ADC
  ADCSRA |= (1 << ADSC);        // Start the first conversion
}

ISR(ADC_vect) {
  uint8_t lowByte = ADCL;  // Read the low byte of ADC result
  uint8_t highByte = ADCH; // Read the high byte of ADC result
  
  adcResult = ((uint16_t)highByte << 8) | lowByte;  // Combine the high and low bytes to form a 10-bit result
  
  ADCSRA |= (1 << ADSC);  // Start the next conversion
}