//---------------------------------------------------------------------------------------
// Programm Nr.: 03
// Content     : set (key 1,3) and reset (key 2,4) LED at PORTD on pressing keys
// Author      : digital AG Halle
// Date        : 13.07.2008
// 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

//--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

	//--MAIN LOOP--------------------------------------------------------------------
	
	while(1)
	{
		KEYS=PINC;	//read input byte from PORT C into variable KEYS

		if ((KEYS&226)==!(0x02))	//if key 1 was pressed (PORT C Bit 1)
		{
			PORTD=254;		//set bit 0 at PORTD (LED1->on)	
			//set the full byte
		}
		
		if ((KEYS&228)==!(0x04))	//if key 2 was pressed (PORT C Bit 2)
		{
			PORTD=255;		//reset bit 0 at PORTD (LED1->off)
			//set the full byte	
		}

		//mask = 1110 1000 = 232 dec.
		if ((KEYS&232)==!(0x08))	//if key 3 was pressed (PORT C Bit 3)
		{
			PORTD &= ~(1<<PD1);		//set bit 1 at PORTD (LED2->on)	
			//set single bit to low-level
		}
		
		//mask = 1111 0000 = 240 dec.
		if ((KEYS&240)==!(0x10))	//if key 4 was pressed (PORT C Bit 4)
		{
			PORTD |= (1<<PD1);		//reset bit 1 at PORTD (LED2->off)
			//reset single bit to high-level
		}
	}
}
//--PROGRAMM END------------------------------------------------------------------------

//  ****  examples to change single bits  ****
//
//  PORTD &= ~(1<<PD0); //set bit 0 to low-level
//  PORTD |= (1<<PD0);  //reset bit 0 to high-level
//  PORTD ^= (1<<PD0);  //toggle bit 0 (change from 0 to 1 or from 1 to 0)
//