#include<reg52.h>

#include<intrins.h>

#define uint unsigned int

#define uchar unsigned char

uchar temp;

sbit beep=P1^2;

void delay(uint);

void main()

{   

                 temp=0xfe;

                 P1=temp;

           while(1)

           {

                 temp=_crol_(temp,1);

                 beep=0;

                      delay(120);

                 P1=0xff;

                 beep=1;

                      delay(120);

                 P1=temp;

           }

}

void delay(uint z)

{

      uint x,y;

      for(x=100;x>0;x--)

           for(y=z;y>0;y--);

}

換一個有源的轟鳴器試一下