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// modified from examples/atmega128_timer/main.c!
#include <avr/interrupt.h>
volatile int timer2_ticks;
volatile int port_val;
volatile int port_cnt;
ISR(TIMER2_COMP_vect) {
timer2_ticks++;
}
int main(void) {
volatile int tmp;
int tmp2;
DDRA = 0x01;
PORTA = 0;
/* Set up our timers and enable interrupts */
TCNT2 = 0; /* Timer 2 by CLK/64 */
OCR2 = 124; /* 2ms on 4MHz, CTC mode */
TCCR2 = 0x0b;
TIMSK = _BV(OCIE2);
sei();
tmp = timer2_ticks;
port_cnt = 0;
port_val = PINA & 0xfe;
while(1) {
if(tmp != timer2_ticks) { // toggle about every 2ms
tmp = timer2_ticks;
if((PINA & 0x01) == 0x01) {
PORTA &= 0xfe;
} else {
PORTA |= 0x01;
}
}
tmp2 = PINA & 0xfe;
if(tmp2 != port_val) {
port_val = tmp2;
port_cnt++;
}
}
return 0;
}
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