;********WAVE-E6000/T************************************
;*MCU:          AT89C51                                 *
;*MCU-crystal:  6M                                      *
;*Version:      00                                      *
;*Last Updata:                                          *
;*Author:       www.picavr.com                          *
;*Description: 一旦發(fā)生 INT0 外部中斷，蜂鳴器發(fā)響個(gè)不停 *
;********************************************************
#include <reg51.h>
sbit bb=P3^7;

delay(i)
unsigned int i;
{ unsigned int j;
  while(i--)
   { j=7650;while(j--);}
}

bell()
{ bb=0;delay(20);bb=1;}

int0() interrupt 1
{bell();}

void main(void)
{ P0=0xc0;P2=0x80;delay(10);P0=0xff;P2=0xff;
  P1=0xfe;
  TCON=0x01;
  IE=0x81;
  while(1);
}