serial_communication.c

51单片机开发与应用技术详解(珍藏版)PPT及源码

#include <reg52.h>                    			//头文件
#include <rtx51tny.h> 

#define uchar unsigned char					//宏定义

#define  OUTBUF_LEN  8                      //串行口发送缓冲区的长度
uchar  outbuf_start;                			//串行口发送缓冲区的起点
uchar  outbuf_end;                  			//串行口发送缓冲区的终点
idata    char  outbuf[OUTBUF_LEN];          	//串行口发送缓冲区
uchar  out_task = 0xff;          				//串行口输出任务的任务号

#define  INBUF_LEN  8                      	//串行口接收缓冲区的长度
uchar  inbuf_start;                			//串行口接收缓冲区的起点
uchar  inbuf_end;                  			//串行口接收缓冲区的终点
idata    char  inbuf[INBUF_LEN];           	//串行口接收缓冲区
uchar  in_task = 0xff;          				//串行口输入任务的任务号

#define   CTRL_Q  0x11 
#define   CTRL_S  0x13 

bit   sendfull;                       			//发送缓冲区满标志位
bit   sendactive;                     			//发送激活标志位
bit   sendstop;                       			//发送停止标志位

void putbuf (char c)  
{
  if (!sendfull) 								//判断发送缓冲区满标志位
{                   
if (!sendactive && !sendstop)  				//缓冲区未满，发送器未处于活动态
{ 
      sendactive = 1;
      SBUF = c;                       		//直接发送第一个字符到SBUF，并启动发送
    }
else  
{
      outbuf[outbuf_end++ & (OUTBUF_LEN-1)] = c; //向定义的发送缓冲区传送字符
      if (((outbuf_end ^ outbuf_start) & (OUTBUF_LEN-1)) == 0)  
sendfull = 1;						//缓冲区满标志置位
    }                                 
  }
}


char putchar (char c)  
{
  if (c == '\n')  								//扩展一行新字符
{                   
while (sendfull)  						//如果发送缓冲区满，则等待
{               
      out_task = os_running_task_id ();  		//置位输出任务号
      os_wait (K_SIG, 0, 0);          			//等待信号
      out_task = 0xff;                   		//输出任务号清零
    }
    putbuf (0x0D);                    			//在LF换行符之前发送CR回车符
  }
  while (sendfull)  							//如果发送缓冲区满，则等待
{ 
    out_task = os_running_task_id ();    		//置位输出任务号
    os_wait (K_SIG, 0, 0);            			//等待信号
    out_task = 0xff;                     		//输出任务号清零
  }
  putbuf (c);                         			//发送字符
  return c;                         			//返回字符
}


char _getkey (void)  
{
  while  (inbuf_end == inbuf_start)  			//等待
{
    in_task = os_running_task_id ();    			//置位输入任务号
    os_wait (K_SIG, 0, 0);            			//等待信号
    in_task = 0xff;                     		//输入任务号清零
  }
  return (inbuf[inbuf_start++ & (INBUF_LEN-1)]);	//返回值
}


void serial () interrupt 4 using 2   				//中断响应函数
{    
  unsigned char c;
  bit   start_trans = 0;

  if (RI)  									//RI置1，接收中断
{ 
    c = SBUF;                        			//读SBUF
RI = 0;                          			//中断请求标志RI清零

switch (c)  							//字符处理
{                    
      case CTRL_S:						//如果是CTRL_S
        sendstop = 1;                			//置位sendstop，停止发送
        break;

      case CTRL_Q:						//如果是CTRL_Q
        start_trans = sendstop;     			//开始发送
        sendstop = 0;
        break;

      default:                       			//对于其它字符
        if (inbuf_start + INBUF_LEN != inbuf_end) 	//则读入输入缓冲区
{
          inbuf[inbuf_end++ & (INBUF_LEN-1)] = c;
        }
                                     
        if (in_task != 0xFF) 					//如果是任务等待
isr_send_signal (in_task);			//发送信号
        break;
    }
  }

  if (TI || start_trans)  						//TI置位，发送中断
{ 
    TI = 0;                          			//中断请求标志TI清零
if (outbuf_start != outbuf_end)  				//如果输入缓冲区接收到字符
{           
      if (!sendstop)  						
{              						//发送字符
        SBUF = outbuf[outbuf_start++ & (OUTBUF_LEN-1)];      
        sendfull = 0;                			// sendfull 标志清零
                                     
        if (out_task != 0xFF)  					//如果是任务等待
isr_send_signal (out_task);			//发送信号
      }
    }
    else sendactive = 0;             			//全部发送完,sendactive清零
  }
}


void init_serial (void)  
{
  SCON  = 0x50;                      		//串行口方式1，8位 UART, 允许接收
  TMOD  = 0x20;                      		//定时器方式2，8位自动重装
  TH1   = 0xf3;                      			//波特率2400bit/s
  TR1   = 1;                         			//启动定时器T1
  ES    = 1;                         			//允许串行口中断
}