/*
	T/C0中斷方式測試程序 
	main.c
	MCU:AT90S2313
	時鐘：4MHz
	
	芯藝 2004-09-18
*/

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/signal.h>

#define uchar unsigned char

#define SET_LED PORTD&=0XEF //PD4接發光管
#define CLR_LED PORTD|=0X10

static uchar g_bCount=0;	//中斷計數器
static uchar g_bDirection=0;

//T/C0中斷例程
SIGNAL(SIG_OVERFLOW0)
{
	// 產生中斷周期 T = 256 * 1024 / 4MHz 
	if(++g_bCount >14)		//中斷15次約一秒
	{
		if(g_bDirection)	//反向LED控制腳
			SET_LED,g_bDirection=0;
		else
			CLR_LED,g_bDirection=1;	
			
		g_bCount=0;
	}
}

int main(void)
{
	DDRD=0X10;
	PORTD=0X10; 

	TCNT0=0; // T/C0開始值 
	TCCR0=5; // 預分頻 ck/1024 ,計數允許
	
	TIMSK=_BV(TOIE0);
	sei();
	
	while(1);
}