藍橋杯單片機開發板，為什么用這個程序上電時蜂鳴器會響

ID:794573 · 發表于 2020-7-17 11:28

本帖最后由單片機1號于 2020-7-18 09:55 編輯

#include "reg52.h"
sbit L1=P0^0;
sbit key=P3^0;
void delay(unsigned int t)
{
      while(t--);
}
void hc138(unsigned char ymq)
{
      switch(ymq)
      {
            case 4:P2=(P2&0x1f)|0x80;break;
            case 5:P2=(P2&0x1f)|0xa0;break;
      }
}
void fmq() //1Ø±Õ·äÃùÆ÷oíLED
{
      hc138(5);
      P0=0x00;
      hc138(4);
      P0=0xff;
}
unsigned char n=0;
unsigned char pwm=0;
void keyan()
{
      if(key==0)
      {
            delay(100);
            if(key==0)
            {
                     switch(n)
                     {
                              case 0:L1=0;TR0=1;n=1;pwm=10; break;
                              case 1:pwm=50;n=2;break;
                              case 2:pwm=90;n=3;break;
                              case 3:L1=1;TR0=0;n=0;break;
                     }
                     while(key==0);
            }
      }
}
unsigned char i=0;
void iot0()
{
      TMOD=0x01;
      EA=1;
      ET0=1;
      TH0=(65536-100)/256;
      TL0=(65536-100)%256;
}
void int0() interrupt 1
{
      TH0=(65536-100)/256;
      TL0=(65536-100)%256;
      i++;
      if(i==pwm)
      {
            L1=1;
      }
      if(i==100)
      {
            L1=0;
            i=0;
      }
}
void main()
{
      iot0();
      fmq();
      hc138(4);

      while(1)
      {
            keyan();
      }
}