/*
Copyright (c) 2008, Nigel Batten.
Contactable at <firstname>.<lastname>@mail.com

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

	1.	Redistributions of source code must retain the above copyright
		notice, this list of conditions and the following disclaimer.
	2.	Redistributions in binary form must reproduce the above copyright
		notice, this list of conditions and the following disclaimer in the
		documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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===============================================

A demonstration of controlling 8 LEDs from 8 pins.
Nigel Batten
September 2008

Written for a 'factory setting' Mega8 (highbyte: 0xd9, lowbyte:  0xe1)
e.g. running on 1Mhz internal RC oscillator.

(Don't forget that your programmer may need to be on it's "slow" setting)
*/

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

// define the processor speed if it's not been defined at the compiler's command line.
#ifndef F_CPU
#define F_CPU 1000000
#endif


int main (void)
{
	DDRD = 0b11111111 ; // set all pins on port D to be outputs...
	PORTD = 0b00000001 ; // start with just one LED on...

	/*
	// a very simple single direction sweep...
	while(1)
	{
		for( PORTD = 0b00000001 ; PORTD != 0b10000000 ; PORTD <<= 1 )
		{
			_delay_ms(60) ;
		}
	}
	*/

	// a very simple back and forth sweep
    while(1)
    {
		for (PORTD = 0b00000001 ; PORTD != 0b10000000 ; PORTD <<= 1 )
		{
			_delay_ms(60) ;
		}
		for (; PORTD != 0b00000001 ; PORTD >>= 1 )
		{
			_delay_ms(60) ;
		}
	}
	
	
	
    return(0);
}