#include "reg52.h"

typedef unsigned char u8;
typedef unsigned int u16;

sbit beep = P2^5;


void delay(u16 i)
{
     while(i--);
}

void main()
{

    while(1){
    
        beep = ~beep;    //高低电平来回变换
        delay(10);

        beep = 1;        //改变占空比，来控制声音大小
        delay(10);
        beep  = 0;
        delay(5);

    
    }

}