u1.c

这是串口通信的下位机测试程序

#include <reg51.h>

void init_com();

void changeinto();
bit  read_flag=0;
unsigned char astring;
static unsigned char xianshichar;

void main()
{
	init_com();

	EA=1; ES=1;       //开中断，允许串行口中断
	REN=1;            //允许串口中断            
     
    P0=0;
   
    while(1)
    {
          if(read_flag)  //如果取数标志已置位，就将读到的字符串从串口发出 
          {   changeinto();
               read_flag=0; //取数标志清0  
			   P0=xianshichar;
			   
          }
    }
}

void init_com( void )
{
    TMOD=0x20;         /*晶振11.0592，波特率2400，方式3*/
    TL1=0x0f3;
    TH1=0x0f3;
    SCON=0xd8;        /*串口接受字符RI置位，允许串口接收*/
    PCON=0x00;
    TR1=1;
}


//串口接收中断
void serial () interrupt 4 using 3 
{
    unsigned char ch;
	ch=SBUF;
    if(RI)                         //确实有接收中断了
    {
	    RI = 0;
        astring=ch;
		
		read_flag=1;
	
    }
}
void changeinto()
{
  switch(astring)
    { 	case 0x0: xianshichar=0x7e;break;
		case 0x1: xianshichar=0x48;break;
		case 0x2: xianshichar=0x3d;break;
		case 0x3:	xianshichar=0x6d;break;
		case 0x4:	xianshichar=0x4b;break;
		case 0x5:	xianshichar=0x67;break;
		case 0x6:	xianshichar=0x77;break;
		case 0x7:	xianshichar=0x4e;break;
		case 0x8:	xianshichar=0x7f;break;
		case 0x9:	xianshichar=0x6f;break;
       default: break;
      
	}
}