//---------------------------------------------------------------------------------------
// Programm Nr.: 04
// Content     : toggle all LEDs at PORTD on pressing keys 1 to 4
// Author      : digital AG Halle
// Date        : 14.07.2008
// System      : ATmega8-16PU - Dai Hoc Hue Development Board
//---------------------------------------------------------------------------------------

//--included Files-----------------------------------------------------------------------

#include <avr/io.h>

//--declarations-------------------------------------------------------------------------

uint8_t KEYS; 		//8-Bit integer variable (0...255) for actual key-value
uint8_t KEYS_OLD;	//variable for last key-value

//--MAIN PROGRAMM------------------------------------------------------------------------

int main()
{

	//--INITIALISATION---------------------------------------------------------------

	DDRC=225;	//PORT C: Bit 1,2,3,4 are inputs (Keys 1 - 4)
	PORTC=30;	//PORT C: Bit 1,2,3,4 internal Pullup-Resistors active

	DDRD=255; 	//Port D: all Bits defined as output (for the status LEDs)


	//--PROGRAMM CODE BEFORE MAIN LOOP (USED JUST ONE TIME)--------------------------

	PORTD=255; 	//Every LED at PORT D is off
	
	KEYS_OLD=PINC;  //initialise KEYS_OLD (PINC should be 255 at that moment)


	//--MAIN LOOP--------------------------------------------------------------------
	
	while(1)
	{
		KEYS=PINC;	
		
		if (KEYS_OLD!=KEYS) 	
		{			
			//bit will be changed without touching the other bits

			if ((KEYS&226)==!(0x02))  	//Key 1
			{
				PORTD ^= (1<<PD0);	   
				PORTD ^= (1<<PD1);
				//toggle bits 0 and 1
			}

			if ((KEYS&228)==!(0x04))	//Key 2
			{
				PORTD ^= (1<<PD2);	   
				PORTD ^= (1<<PD3);
				//toggle bits 2 and 3
			}

			if ((KEYS&232)==!(0x08))	//Key 3
			{
				PORTD ^= (1<<PD4);	   
				PORTD ^= (1<<PD5);
				//toggle bits 4 and 5
			}

			if ((KEYS&240)==!(0x10))	//Key 4
			{
				PORTD ^= (1<<PD6);	   
				PORTD ^= (1<<PD7);
				//toggle bits 6 and 7
			}
		}
		
		KEYS_OLD=KEYS;	

	}
}
//--PROGRAMM END-------------------------------------------------------------------------