串口通讯

#include <reg52.h>

//#define   BUFFERLEGTH 10

unsigned int shuju[4]={0xff,0xfe};
 unsigned char recbuff[2]={0,0};
 unsigned char rec_count=0;
 enum{WAIT,START,DATA};  // 状态机
 char u_stat=WAIT;

sbit  spc=P0^6;     //beep

void UART_init()
{
                      //初始化串行口和波特率发生器
SCON =0x50;           //选择串口工作方式1，打开接收允许
TMOD =0x20;           //定时器1工作在方式2，定时器0工作在方式1
TH1 =0xfA;            //实现波特率9600（系统时钟11.0592MHZ）
PCON = 0x80;
TR1 =1;               //启动定时器T1
ET1 =0;
ES=1;                 //允许串行口中断
PS=1;                 //设计串行口中断优先级
EA =1;                //单片机中断允许
}



void COM_send(void)
{
    unsigned char point;
    for(point=0;point<4;point++)       //连续发送二十位数据 
   {
    SBUF=shuju[point];   //把缓存区的数据都发送到串口
    while(!TI);
    TI=0;
   }
}




//--------------------------------------------------------------------------------------------------
void com_interrupt(void) interrupt 4 using 3
{
           unsigned char RECEIVR_buffer;
   


      ES=0;

          if(RI)
          {
              RI=0;
            RECEIVR_buffer=SBUF;

            switch(u_stat)
            {
                case WAIT:
                    if(RECEIVR_buffer==0xff)
                    {
                        u_stat=START;
                        
                            
                    }
                    else  u_stat=WAIT;
                     break;
                
                case START:

                    if(RECEIVR_buffer==0xfe)
                    {
                        u_stat=DATA;
                        
                    }
                    else u_stat=WAIT;
                
                    break;
                case DATA:
                    if(RECEIVR_buffer==0xee)
                    {
                        u_stat=WAIT;
                    }    
                    else 
                    {
                    //    COM_send();
                        recbuff[rec_count]=RECEIVR_buffer;
                        rec_count++;
                        if(rec_count>1)  rec_count=0;
                    }
                    break;
                    
            }
          }
     ES=1;
         
}