serial.c

linux下串口设备源程序,并详细分析了串口设置的方法.

/*	serial.c by [e-mail]		*/ 

#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <time.h>

#include "serial.h"


/*定义波特率的合法取值*/
static int  speed_arr[]={ B115200, B38400, B19200, B9600, B4800, B2400, B1200, B300, B38400, B19200, B9600, B4800, B2400, B1200, B300, };

/*定义对应的波特率数值*/
static int  name_arr[]={ 115200, 38400, 19200, 9600, 4800, 2400, 1200, 300, 38400, 19200, 9600, 4800, 2400, 1200, 300,};

int tty_raw(int tty_fd)
{
	struct termios t;

	if (tcgetattr(tty_fd, &t) < 0)
		return -1;

	t.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
	t.c_iflag &= ~(BRKINT | PARMRK | INLCR | IGNCR | ICRNL | INPCK | ISTRIP | IXON);
	t.c_cflag &= ~(CSIZE);
	t.c_cflag |= CS8;
//	t.c_cflag = 0;
	t.c_oflag &= ~(OPOST);

	t.c_cc[VMIN] = 1;
	t.c_cc[VTIME] = 0;

	if (tcsetattr(tty_fd, TCSAFLUSH, &t) < 0)
		return -1;

	return 0;
}

int init_serial(char* dev)	{
	int fd=open(dev,O_RDWR | O_NOCTTY, 0);
	if(fd<0)	{
		printf("cannot open %s\n",dev);
		exit(-1);
	}
	else
	{
	}
//		printf("%s open successfully.\n",dev);
	return fd;
}

void set_speed(int fd,int speed)	{
	int i,status;
	struct termios opt;
	tcgetattr(fd,&opt);
	for(i=0;i<sizeof(speed_arr)/sizeof(int);i++)	{
		if(speed == name_arr[i])	{
			tcflush(fd,TCIOFLUSH);/*TCIOFLUSH
   						flushes both data received but not read, and  data  written  but
              					not transmitted.*/
			cfsetispeed(&opt,speed_arr[i]);/*设置串口输入速度*/
			cfsetospeed(&opt,speed_arr[i]);/*设置串口输出速度*/
			status = tcsetattr(fd,TCSANOW,&opt);	/*设置设备工作模式*/
			if(status != 0)	perror("tcsetattr fd error!");
			break;
		}
		tcflush(fd,TCIOFLUSH);
	}
}

int set_parity(int fd,int databits,int stopbits,int parity)	{
	/**
	 *@brief   设置串口数据位，停止位和效验位
	 *@param  fd     类型  int  打开的串口文件句柄
	 *@param  databits 类型  int 数据位   取值 为 7 或者8
	 *@param  stopbits 类型  int 停止位   取值为 1 或者2
	 *@param  parity  类型  int  效验类型 取值为N,E,O,,S
	 */
	struct termios opt;
	if(tcgetattr(fd,&opt) != 0)	{	/*得到设备当前模式*/
		perror("setup serial...");
		return 0;
	}
	/* 设置数据位数前，首先使用‘CSIZE’屏蔽数据位数 */
	opt.c_cflag &= ~CSIZE;		/*CSIZE  Character size mask.  Values are CS5, CS6, CS7, or CS8.*/
	switch(databits)	{	/*设置数据位数*/
	case 7:
		opt.c_cflag |= CS7;	/*设置数据位数=7*/
		break;
	case 8:
		opt.c_cflag |= CS8;	/*设置数据位数=8*/
		break;
	default:
		printf("unsupport data size.\n");
		return 0;
	}
	
	switch(parity)	{	/*设置串口校验位*/
	case 'n':
	case 'N':
		opt.c_cflag &= ~PARENB;	/*set the PARENB bit to zero-------disable parity checked*/
		opt.c_iflag &= ~INPCK;	/*set the INPCK bit to zero--------INPCK means inparitycheck(not paritychecked)*/
		break;
	case 'o':
	case 'O':
		opt.c_cflag |= (PARENB|PARODD);
		opt.c_iflag |= INPCK;
		break;
	case 'e':
	case 'E':
		opt.c_cflag |= PARENB;
		opt.c_cflag &= ~PARODD;
		opt.c_iflag |= INPCK;  
		break;
	case 's':
	case 'S':
		opt.c_cflag &= ~PARENB;
		opt.c_cflag &= ~CSTOPB;	/*CSTOPB---Set two stop bits, rather than one.*/
		break;
	default:
		printf("unsupported parity.\n");
		return 0;
	}
	
	switch(stopbits)	{	/*设置停止位*/
		case 1:
			opt.c_cflag &= ~CSTOPB;
			break;
		case 2:
			opt.c_cflag &= CSTOPB;
			break;
		default:
			printf("unsupported stopbits.\n");
			return 0;
	}
	
	if(parity !='n')	opt.c_iflag |= INPCK;
	tcflush(fd,TCIFLUSH);
	opt.c_cc[VTIME] = 1;
	//opt.c_cc[VTIME] = 5;
	//opt.c_cc[VTIME] = 150;
	opt.c_cc[VMIN] = 0;
	
	if(tcsetattr(fd,TCSANOW,&opt) != 0)	{
		perror("\n");
		return 0;
	}
	return 1;
}