// Copyright 2006 Yamane Akira
// IccAVR Sample program
// Target: Device: ATmega48
// Subject: Change Internal RC Osscillator Frquency:
//     1MHz ->4MHz -> 1MHz->
// Programmed by Akira Yamane
// May 25 05

#include <iom48v.h>
#include <macros.h>

void port_init(void)
  {
  PORTB = 0xFF;
  DDRB = 0xFF;

  PORTC = 0x7F;
  DDRC = 0x00;
    
  PORTD = 0xFF;
  DDRD = 0xFF;  
  }
  
// delay function
void delay()    
  {
   unsigned char a,b;
    for (a = 1; a; a++)
	  for (b = 1; b; b++)
	  ;
  }

// CLK Prescaler set to 4Hz
void clkpr_4_set(void) 
  {
  CLKPR = 0x80;
  CLKPR = 0x01;
  }

// CLK Prescaler set to 1MHz
void clkpr_1_set(void)  
  {
  CLKPR = 0x80;
  CLKPR = 0x03;
  }

// LED bit i On Function
void LED_ON(int i)
  {
  PORTB = ~BIT(i);
  delay();
  }

void main(void)
  {
   int i;
  port_init();

    while(1)
	{
    clkpr_1_set();	  
	  for (i = 0; i < 8; i++)
	    LED_ON(i);
	  for (i = 8; i > 0; i--)
	    LED_ON(i);
   clkpr_4_set();
	  for (i = 0; i < 8; i++)
	    LED_ON(i);
	  for (i = 8; i > 0; i--)
	    LED_ON(i);    
	}
  }