#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/eeprom.h>
#include <avr/pgmspace.h>
#include <stdint.h>
#include <stdbool.h>

int main() {
	static uint8_t delay EEMEM=2;
	bool swSnel, swTraag, oldswSnel=false, oldswTraag=false;
	volatile uint16_t i;
	DDRB=0xFF; PORTB=0xFF; DDRA=0x00;
	OCR0=36*eeprom_read_byte(&delay); TCCR0=0x0D;
	TIMSK|=1<<OCIE0; sei();
	while(1) {
		swTraag=~PINA&0x08; /* SW3 */
		if (swTraag!=oldswTraag) {
			oldswTraag=swTraag;
			if (swTraag && eeprom_read_byte(&delay)<5) {
				eeprom_write_byte(&delay, eeprom_read_byte(&delay)+1);
				OCR0=eeprom_read_byte(&delay)*36;
			}	
		}
		swSnel=~PINA&0x04; /* SW2 */
		if (swSnel!=oldswSnel) {
			oldswSnel=swSnel;
			if (swSnel && eeprom_read_byte(&delay)>1) {
				eeprom_write_byte(&delay, eeprom_read_byte(&delay)-1);
				OCR0=eeprom_read_byte(&delay)*36;
			}
		}
		for (i=0; i<3000; ++i); /* anti dender vertraging */
	}
	return 0;
}

ISR(TIMER0_COMP_vect) {
	static uint8_t patroon[] PROGMEM ={
		0x00,0x80,0xC0,0x40,0x60,0x20,0x30,0x10,
		0x18,0x08,0x0C,0x04,0x06,0x02,0x03,0x01,0x00
	};
	static uint8_t j=0;
	static bool heen=true;
	PORTB=~pgm_read_byte(&patroon[j]);
	heen = heen ? ++j!=sizeof patroon-1 : --j==0;
}