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单片机原理与应用实例教程 单片机原理与应用实例教程

#include "REG51.h"
unsigned char tag = 1;
void  INT_0(void) interrupt 0
{
	if( tag == 1 )
		tag = 0;
	else
		tag = 1;
} 

void delay(){
	unsigned char i,j,k;
	for(i=0; i<0xff; i++)
	{
		for(j=0; j<0xff; j++)
		{
			for(K=0; K<10; K++)
			{
			}
		}
	}
}

main(){
	unsigned char i,j;
	unsigned char m = 0xfe;
	IE = 0x81;
	IT0 = 1;
	while( 1 )
	{
		if( tag == 0 )
		{
			i	= m >> 7;
			j	= m << 1;
			m	= i | j;
		}
		else
		{
			i	= m << 7;
			j	= m >> 1;
			m	= i | j;
		}
		P1 = m;
		Delay();
	}
}