（3）单片机蜂鸣器

#include <reg52.h>
#include <intrins.h>
typedef unsigned char u8;
typedef unsigned int u16;
u16 i;
sbit beep=P1^5;
void delay(u16 i)
{
	while(i--);
}

void main()
{	
	while(1)
	{
	i=300;
	delay(5000);
	while(i)
	{
	i=i-1;
	beep=0;
	delay(10);
	beep=1;
	delay(10);
	beep=0;
	delay(5);
	beep=1;
	delay(5);
	
	}}
}