复件 recesive.c

汽车号牌识别系统

#include <AT89x051.H>

unsigned char receivebits;
unsigned char receivebytes;
unsigned char buf[2];
bit flag;
bit start;
int  i;
int j;

void main(void)
{
			P3_3=1;
			P3_4=1;
		    P3_5=1;
      	    P3_7=1;
  SP=0X59;
  P3_0=1;                       //置为接收
for(i=0;i<=25;i++)
{	for(j=0;j<=10000;j++)
		{
		P3_1=1;
		P3_1=0;
	}
}

			P3_3=1;
			P3_4=1;
		    P3_5=1;
      	    P3_7=1;
  EX0=1;
  IT0=1;
  receivebits=0;                 //接收的位=0
  receivebytes=0;                //接收的字节=0
  buf[0]=0;
  buf[1]=0;                     //置空接收缓冲

  flag=0;                       //没有接收到控制数据
  
  start=0;                             //数据线空闲
  EA=1;
  //P0=0;                                //输出0，关灯

  while(1)
 {
    P3_1=0;
    P3_1=1;
    if(flag)                         //如果有控制数据
  {  
       if((buf[1]&0x01)==0x00)
	   	   P3_3=0;
		  else
 		  P3_3=1;
 
	   if((buf[1]&0x02)==0x00)
	   	 P3_4=0;
		  else
 		  P3_4=1;
	   if((buf[1]&0x04)==0x00)
	   	   P3_5=0;
		   else
		   P3_5=1;

	   if((buf[1]&0x08)==0x00)
	       P3_7=0;
		   else
		   P3_7=1;

	      flag=0;
	       
     }
}

}

receivedata()interrupt 0 using 3
{
  bit  databit;
  databit=P3_0;                 //检测数据线
  if(start==0)                 //如果目前空闲
  {
     if(databit==0) start=1;   //如果检测到低电平，则置数据线开始传输数据
     return;      
  }
  
  else                         //如果正在传输数据
  {   
       receivebits++;            //接收的位+1
       buf[receivebytes]=buf[receivebytes]<<1;
       if(databit)  buf[receivebytes]++;       //接收的数据位进缓冲
       if(receivebits==8)                     //如果接收了1字节
       {
         start=0;                            //置数据线空闲
         receivebits=0;                     //接收的位计数=0
         receivebytes++;                   //接收的字节计数+1
         if(receivebytes==2)               //如果接收了2字节
         {
           // if(buf[0]==P2)
		    
		    flag=1;     //如果组号相等，置接收到控制数据
            receivebytes=0;               //接收的字节计数=0
         }
       }    
   }
}