抢答.c

单片机C语言15个实验附有原理图和程序 是我的课程作业 以经过实践验证

#include <stdio.h>
#include <reg51.h>
#include <intrins.h>

#define hi2 0xff
#define lo2 0x00
#define hi3 0xff
#define lo3 0x80
#define hi 0x3c
#define lo 0xb0
#define time 15
sbit P30=P3^0;sbit P37=P3^7;sbit clk=P0^7;sbit sda=P0^6;               //74LS164
unsigned char key,key1,key_flag,key_count,disp[4],mask=0xee,led_no=0,flag;
unsigned char code ledk[12]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x00,0x73};
char sec=time,t0_count;
void delay(unsigned int n)
{ unsigned int i,j;
  for(i=0;i<n;i++)
     for(j=0;j<n;j++)
       ;}
void shift(unsigned char dx)
{unsigned char j=0;
 while(j<8)
	{if((dx&0x80)!=0) sda=1;
       else  sda=0;
	   clk=0;clk=1;
	   dx<<=1;j++;}  }
//===============
unsigned char get_char()
{unsigned char key_code;
  static unsigned char column=1;//column 从1开始
  if (P37==0 && key_flag==1){key_code=column;key_flag=0;key_count=0;}
     else key_code=0xff;
  mask=_crol_(mask,1);
  column++; if(column>4)column=1; 
  led_no++; if(led_no>3)led_no=0;
  return(key_code);}
void key_func(key)
 {switch (key)
   {case 1:  
    case 2:  
    case 3: 
    case 4:key1=key;flag=1;break;
    default: ;}  }
//============
void t0() interrupt 1 
{ TH0=hi;TL0=lo;t0_count++;key_count++;
  if(t0_count==20){if(flag==1)sec--; //if(flag==1 && sec!=-1)sec--;
                   t0_count=0;}
  if(sec==-10){sec=time;flag=0;}   }                                              

void t1() interrupt 3
  {if(sec==time){TH1=hi3;TL1=lo3;}  //两种音调
     if(sec==time-1){TH1=hi2;TL1=lo2;} 
       if(sec<=0){TH1=hi3;TL1=lo3;}
  P30=!P30;  }

void disp_out() 
 {disp[3]=key1;disp[2]=10;
   if(sec>=0){disp[1]=sec/10;disp[0]=sec%10;}
     else {disp[1]=0;disp[0]=0;}   }  //from sec=0 to sec=-3 display "00"

void out()
 {if(flag==1){disp_out();                  //two modes of display
              shift(ledk[disp[led_no]]); P2=mask; }
        else {P2=mask|0x07;shift(ledk[11]);} //dispplay "P"
  if(flag==1 && (sec>=time-1||sec<=0))TR1=1;   //sound
         else {TR1=0;P30=1;}                   //stop sound
		 }
//====================
void main(void)
 {TMOD=0x11;TH0=hi;TL0=lo;EA=1;ET0=1;TR0=1;ET1=1;P30=1;flag=0;// no TR1
   while(1)
     {key=get_char( );delay(20);
      if(flag==0)key_func(key);//禁再抢答
      out();
      if(key_flag==0 && key_count==10 && P37==1)key_flag=1;}		   
 }