avr/tron-bag/main.c

#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <dio.h>

#define FPS                 10
#define FPS_MS              1000 / FPS
#define MULT                5

typedef struct {
    uint8_t value;
    int8_t inc;
} counter_t;

void counter_update(counter_t *self) {
    int16_t value = self->value;
    value += self->inc;

    if (value >= 255) {
        self->value = 255;
        self->inc = -1;
    } else if (value <= 0) {
        self->value = 0;
        self->inc = 1;
    } else {
        self->value = value;
    }
}

int main(void) {
    DDRB = 0xff;
    PORTB = 0;

    GTCCR = 0;
    TCCR0A = _BV(COM0A1) | _BV(COM0B1) | _BV(WGM01) | _BV(WGM00);
    TCCR0B = _BV(CS00);

    counter_t red = (counter_t){ .value = 128, .inc = 1 };
    counter_t blue = (counter_t){ .value = 0, .inc = 1 };

    while(1) {
        OCR0A = red.value;
        OCR0B = blue.value;

        _delay_ms(10);

        counter_update(&red);
        counter_update(&blue);
    }

    return 0;
}