Linux串口编程

Linux串口编程

2012-06-28 09:45   117人阅读   评论(0)   收藏   举报

最近使用了linux的串口，整理了一下应用程序调用的API，希望将来有用。

主要有两个文件SerDrive.h盒SerDrive.c

//=======================================================

SerDrive.h

 #ifndef SERDRIVE_H
 #define SERDRIVE_H
 //=======================
 //串口名字
 #define     TTY0_NAME   "/dev/ttySAC0"
 #define     TTY1_NAME   "/dev/ttySAC1"
 #define     TTY2_NAME   "/dev/ttySAC2"


 //串口
 #define     TTYS0   1
 #define     TTYS1   2
 #define     TTYS2   3
 //波特率
 #define     BAUD_2400       2400
 #define     BAUD_4800       4800
 #define     BAUD_9600       9600
 #define     BAUD_115200     115200
 #define     BAUD_460800     460800
 //奇偶校验位
 #define     PARITY_ODD    'O' //奇数
 #define     PARITY_EVEN   'E' //偶数
 #define     PARITY_NONE   'N' //无奇偶校验位
 //停止位
 #define     STOP_BIT_1     1
 #define     STOP_BIT_2     2
 //数据位
 #define     DATA_BIT_7     7
 #define     DATA_BIT_8     8
 //========================================
 //串口API

 /*打开串口函数*/
 int open_port(int fd,int comport);
 //串口配置的函数
 int set_opt(int fd,int nSpeed, int nBits,
             char nEvent, int nStop);
 //从串口中读取数据
 int read_datas_tty(int fd,char *rcv_buf,int TimeOut,int Len);
 //向串口传数据
 int send_data_tty(int fd, char *send_buf,int Len);


 //==============
 #endif // SERDRIVE_H

//*****************************************************

SerDrive.c

 #include "SerDrive.h"
 //===========================================

 #include     <stdio.h>      /*标准输入输出定义*/
 #include     <stdlib.h>     /*标准函数库定义*/
 #include     <unistd.h>     /*Unix 标准函数定义*/
 #include     <sys/types.h>
 #include     <sys/stat.h>
 #include     <fcntl.h>      /*文件控制定义*/
 #include     <termios.h>    /*POSIX 终端控制定义*/
 #include     <errno.h>      /*错误号定义*/

 //=============================================
 #define DEVICE_TTYS 1



 //=============================================
 /*打开串口函数*/
 int open_port(int fd,int comport)
 {

        if (comport==1)//串口 1
        {
             fd = open( TTY0_NAME, O_RDWR|O_NOCTTY|O_NDELAY);
            if (-1 == fd){
                    perror("Can't Open Serial Port");
                    return(-1);
             }
        }
        else if(comport==2)//串口 2
        {
             fd = open( TTY1_NAME, O_RDWR|O_NOCTTY|O_NDELAY);
             if (-1 == fd){
                    perror("Can't Open Serial Port");
                    return(-1);
             }
        }
        else if (comport==3)//串口 3
        {

            fd = open( TTY2_NAME, O_RDWR|O_NOCTTY|O_NDELAY);
             if (-1 == fd){
                    perror("Can't Open Serial Port");
                    return(-1);
             }
        }
     /*恢复串口为阻塞状态*/
        if(fcntl(fd, F_SETFL, 0)<0)
             printf("fcntl failed!\n");
        else
             printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));
     /*测试是否为终端设备*/
        if(isatty(STDIN_FILENO)==0)
             printf("standard input is not a terminal device\n");
        else
             printf("isatty success!\n");
        printf("fd-open=%d\n",fd);
        return fd;
 }
 //串口配置的函数
 int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
 {
       struct termios newtio,oldtio;
       /*保存测试现有串口参数设置，在这里如果串口号等出错，会有相关的出错信息*/
       if  ( tcgetattr( fd,&oldtio)  !=  0) {
              perror("SetupSerial 1");
              return -1;
       }
       bzero( &newtio, sizeof( newtio ) );
       /*步骤一，设置字符大小*/
       newtio.c_cflag  |=  CLOCAL | CREAD;
       newtio.c_cflag &= ~CSIZE;
       /*设置停止位*/
       switch( nBits )
       {
       case 7:
              newtio.c_cflag |= CS7;
              break;
       case 8:
              newtio.c_cflag |= CS8;
              break;
       }
       /*设置奇偶校验位*/
       switch( nEvent )
       {
       case 'O': //奇数
              newtio.c_cflag |= PARENB;
              newtio.c_cflag |= PARODD;
              newtio.c_iflag |= (INPCK | ISTRIP);
              break;
       case 'E': //偶数
              newtio.c_iflag |= (INPCK | ISTRIP);
              newtio.c_cflag |= PARENB;
              newtio.c_cflag &= ~PARODD;
              break;
       case 'N':  //无奇偶校验位
              newtio.c_cflag &= ~PARENB;
              break;
       }
       /*设置波特率*/
       switch( nSpeed )
       {
       case 2400:
              cfsetispeed(&newtio, B2400);
              cfsetospeed(&newtio, B2400);
              break;
       case 4800:
              cfsetispeed(&newtio, B4800);
              cfsetospeed(&newtio, B4800);
              break;
       case 9600:
              cfsetispeed(&newtio, B9600);
              cfsetospeed(&newtio, B9600);
              break;
       case 115200:
              cfsetispeed(&newtio, B115200);
              cfsetospeed(&newtio, B115200);
              break;
       case 460800:
              cfsetispeed(&newtio, B460800);
              cfsetospeed(&newtio, B460800);
              break;
       default:
              cfsetispeed(&newtio, B9600);
              cfsetospeed(&newtio, B9600);
             break;
       }
       /*设置停止位*/
       if( nStop == 1 )
              newtio.c_cflag &=  ~CSTOPB;
       else if ( nStop == 2 )
              newtio.c_cflag |=  CSTOPB;
       /*设置等待时间和最小接收字符*/
       newtio.c_cc[VTIME]  = 0;
       newtio.c_cc[VMIN] = 0;
       /*处理未接收字符*/
       tcflush(fd,TCIFLUSH);
       /*激活新配置*/
       if((tcsetattr(fd,TCSANOW,&newtio))!=0)
       {
              perror("com set error");
              return -1;
       }
       printf("set done!\n");
       return 0;
 }
 //======================================================
 //从串口中读取数据
 int read_datas_tty(int fd,char *rcv_buf,int TimeOut,int Len)
 {
         int retval;
         fd_set rfds;
         struct timeval tv;
         int ret,pos;
         tv.tv_sec = TimeOut/1000;//set the rcv wait time
         tv.tv_usec = TimeOut%1000*1000;//100000us = 0.1s

         pos = 0;
         while(1){
            FD_ZERO(&rfds);
            FD_SET(fd,&rfds);
            retval = select(fd+1,&rfds,NULL,NULL,&tv);
            if(retval ==-1)
            {
                 perror("select()");
                 break;
            }
            else if(retval)
            {
                 ret= read(fd,rcv_buf+pos,1);
                     if(-1 == ret){
                             break;
                   }

               pos++;
               if(Len <= pos){
                     break;
               }
            }
            else
            {
                 break;
            }
         }

         return pos;
 }

 //向串口传数据
 int send_data_tty(int fd, char *send_buf,int Len)
 {
     ssize_t ret;

     ret = write(fd,send_buf,Len);
     if (ret == -1)
         {
                 printf ("write device %s error\n", DEVICE_TTYS);
                 return -1;
         }

     return 1;
 }

//**********************************************************************

//调用例子

 #include "SerDrive.h"
 //======================================
 int SerFd = -1;
 void    ProcessInit(int argc, char *argv[])
 {
     /*打开串口函数*/
     SerFd = open_port(SerFd,TTYS1);
     if(0 < SerFd){
         set_opt(SerFd,BAUD_2400,
                 DATA_BIT_8, PARITY_NONE, STOP_BIT_1);
     }else{
         printf("open_port ERROR !\n");
     }
 }

 int main ( int argc, char *argv[])
 {
     int nTmp = 0;
     char Buf[1024];
     ProcessInit(argc,argv);

     while(1){
         //从串口中读取数据
         nTmp = read_datas_tty(SerFd, Buf,100,1024);
         if(0<nTmp){
             //printf("rcv len=%d,data:%s\n",nTmp,Buf);
             //向串口传数据
             send_data_tty(SerFd, Buf,nTmp);
         }
     }
 }