roboforum.ru

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

#define L_TSOP  (1<< PINA6)
#define R_TSOP  (1<< PINA7)

#define L_LED   (1<< PINA4)
#define R_LED   (1<< PINA5)

unsigned char   radarR = 0, radarL = 0;

register unsigned char  count   asm("r3");
register unsigned char  r       asm("r4");
register unsigned char  l       asm("r5");

ISR(SIG_OUTPUT_COMPARE0) {
    if (count++ > 150) {
        radarR = r;
        radarL = l;
        r = l = count = 0;
    }

    if (count < 140) {
        PORTA ^= R_LED | L_LED;
    }

    if ((PINA & R_TSOP) == 0) r++;
    if ((PINA & L_TSOP) == 0) l++;
}

void RadarInit() {
    r = l = count = 0;

    /* Ports */

    DDRA |= (L_LED | R_LED);
    PORTA |= (R_LED | L_LED);

    DDRA &= ~(L_TSOP | R_TSOP);
    PORTA |= (L_TSOP | R_TSOP);

    /* Timer = 8MHz / (38kHz * 2) */

    TCCR0 = (1 << WGM21) | (0 << CS22) | (0 << CS21) | (1 << CS20);
    OCR0 = 105;
    TIMSK |= (1<< OCIE0);
}