/*
 * Vaja4.c
 *
 * Created: 22.03.2013 13:12:32
 *  Author: maticpi
 */ 

#include <avr/io.h>

void Init();
char GetKey();
void ReadKBD();
char lastkey;

int main(void)
{
	char cmd;
	Init();
	while(1)
	{
		ReadKBD();
		if ((cmd=GetKey()))
		{
			switch (cmd)
			{
				case 1:	PORTB++; break;
				case 2: PORTB--; break;
				case 3: PORTB = 0; break;
				case 4: PORTD ^= 0x80; break;
				default: break;
			}
		}			
	}
}

void Init()
{
	//IO port init
	PORTA=0x08;
	PORTB=0x01;
	PORTC=0x3E;	//0011 1110
	PORTD=0x7D;	//0111 1101
	//1-out, 0-in
	DDRA=0xF0;
	DDRB=0xFF;
	DDRC=0xC1;
	DDRD=0x82;
}

void ReadKBD()
{
	static char oldD;
	char newD=(PIND>>2) & 0x0F;
	char pressed = (newD ^ oldD) & oldD;
	if (pressed & 0x01) lastkey=1;
	if (pressed & 0x02) lastkey=2;
	if (pressed & 0x04) lastkey=3;
	if (pressed & 0x08) lastkey=4;
	oldD=newD;
}

char GetKey()
{
	char tmp=lastkey;
	lastkey=0;
	return tmp;	
}