给出打开串口函数

int open_tty(char tty[])

{

	int fd;

	char tty_path[32]={0};

	sprintf(tty_path,"/dev/%s",tty);

	fd=tty_open_port(tty_path);

	// PORT_SPEED是一个定义的宏，表示传输速率。数据位为8，无校验位，停止位为1

	tty_set_opt(fd,PORT_SPEED,8,'N',1);

	return fd;

}

该函数接受一个参数，表示你要打开的串口名称，如“ttyS1”，返回串口操作描述符，在调用该函数后，可以根据返回值来判断是否设置成功，如果fd大于0，则返回成功。

该函数还依赖于两个函数，下面也给出（包括用到的头文件）。

#include <stdio.h>

#include <string.h>

#include <sys/types.h>

#include <error.h>

#include <sys/stat.h>

#include <unistd.h>

#include <termios.h>

#include <fcntl.h>

#include <stdlib.h>

extern int tty_open_port(char *tty_num);

extern int tty_set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop);

int tty_open_port(char *tty_num)

{

     int fd = open (tty_num, O_RDWR | O_NOCTTY | O_NDELAY );

     //阻塞 fcntl(fd,F_SETFL,0)  ; //block

     //非阻塞 fcntl(fd,F_SETFL,FNDELAY)  ;

      if (fd == -1)

      {

	  printf ("Can't Open Serial Port %s !\n",tty_num);

	  return -1;

      }

      else

      {

	   //将串口设置成非阻塞的操作

           fcntl(fd,F_SETFL,FNDELAY);

           return fd;

      }

}

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

* 功    能:set serial port speed

* 修改历史: 2011.6.29.

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

int tty_set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)

{

	struct termios newtio,oldtio;

	if  ( tcgetattr( fd,&oldtio)!=0) {

		perror("SetupSerial 1");

		return -1;

	}

	bzero(&newtio, sizeof( newtio ));

	newtio.c_cflag  |=  CLOCAL | CREAD;

	newtio.c_cflag &= ~CSIZE;             //mask the character size bits

	switch( nBits )

	{

	case 7:

		newtio.c_cflag |= CS7;              //data: 7bits

		break;

	case 8:

		newtio.c_cflag |= CS8;              //data: 8bits

		break;

	}

	switch( nEvent )

	{

	case 'O':

		newtio.c_cflag |= PARENB;

		newtio.c_cflag |= PARODD;

		newtio.c_iflag |= (INPCK | ISTRIP);

		break;

	case 'E':

		newtio.c_iflag |= (INPCK | ISTRIP);

		newtio.c_cflag |= PARENB;

		newtio.c_cflag &= ~PARODD;

		break;

	case 'N':

		newtio.c_cflag &= ~PARENB;

		break;

	}

	switch( nSpeed )          //set the bps

	{

	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 19200:

		cfsetispeed(&newtio, B19200);

		cfsetospeed(&newtio, B19200);

		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;

	}

	if( nStop == 1 )                //set the 1bit stop

		newtio.c_cflag &=  ~CSTOPB;

	else if ( nStop == 2 )         //set the 2bit stop

		newtio.c_cflag |=  CSTOPB;

	newtio.c_cc[VTIME]  = 0;

	newtio.c_cc[VMIN] = 0;

	tcflush(fd,TCIFLUSH);

	if((tcsetattr(fd,TCSANOW,&newtio))!=0)

	{

		perror("com set error");

		return -1;

	}

	printf("Current serial speed is %d\n",nSpeed);

	return 0;

}

代码中给出了可以设置成阻塞和非阻塞的操作。

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