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/* this code is taken from examples/anacomp */
#include <avr/interrupt.h>
#include <avr/io.h>
volatile unsigned char isr_count = 0;
volatile unsigned char in_loop = 0;
void init(void) {
// init port B: only port pin 0 to output
DDRB = 0x01;
#ifdef PROC_at90s4433
// set bandgap ref to AIN0
ACSR = _BV(AINBG) | _BV(ACIE);
#else
#ifdef PROC_at90s8515
// AIN0 from external source
ACSR = 0x00;
#else
// set bandgap ref to AIN0
ACSR = _BV(ACBG);
#endif
#endif
}
void set_port(void) {
if((ACSR & _BV(ACO)) == _BV(ACO)) {
PORTB = 0x01; // set output
} else {
PORTB = 0x00; // reset output
}
}
#if defined(PROC_attiny25) || defined(PROC_atmega8) || defined(PROC_at90s4433) || defined(PROC_at90s8515) || defined(PROC_attiny2313) || defined(PROC_atmega16)
ISR(ANA_COMP_vect) {
#else
ISR(ANALOG_COMP_vect) {
#endif
// set port according to comparator output
set_port();
// count isr counter
isr_count++;
}
int main(void) {
init();
// set port to initial state depending on ACO
set_port();
// reset ACIF to not to trigger interrupt immediately after sei
#ifdef PROC_at90s4433
ACSR = _BV(AINBG) | _BV(ACIE) | _BV(ACI);
#else
#ifdef PROC_at90s8515
ACSR = _BV(ACIE) | _BV(ACI);
#else
ACSR = _BV(ACBG) | _BV(ACIE) | _BV(ACI);
#endif
#endif
// enable interrupts
sei();
do {
in_loop = 1;
} while(1); // do forever
}
// EOF
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