//Bron:  https://www.ee-diary.com/2021/07/how-to-use-arduino-analog-comparator.html#


//Definition of interrupt names
#include <avr/io.h>
// ISR interrupt service routine
#include <avr/interrupt.h>

void setup () {
	DDRD |= (1<<PD4);
    DIDR1 |= (1<<AIN0D) | (1<<AIN1D); // Disable Digital Inputs at AIN0 and AIN1
	ADCSRB &= ~(1<<ACME);	//Clear ACME bits in ADCSRB to use external input at AIN1 -ve input
	ACSR = 
	(0 << ACD) |    // Analog Comparator: Enabled
	(0 << ACBG) |   // Clear ACBG to use external input to AIN0 +ve input
	(0 << ACO) |    // Analog Comparator Output: OFF
	(1 << ACI) |    // Analog Comparator Interrupt Flag: Clear Pending Interrupt by setting the bit
	(0 << ACIE) |   // Analog Comparator Interrupt: Disabled 
	(0 << ACIC) |   // Analog Comparator Input Capture: Disabled
	(0 << ACIS1) | (0 << ACIS0);   // Analog Comparator Interrupt Mode: Comparator Interrupt on Output Toggle
}

void loop() {
	if (ACSR & (1<<ACO))
		PORTD |= (1<<PD4);
	else
		PORTD &= ~(1<<PD4);	
}