Linux UART termios socat

$ cat uart_tios.h #ifndef UART_TERMIOS_H #define UART_TERMIOS_H

extern int32_t init_com_port(char* uart_name);

#endif

$ cat uart_tios.c #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <termios.h> #include <errno.h> #include <getopt.h> #include <time.h> #include <sys/select.h> #include "uart_tios.h"

int setOpt(int fd) { struct termios newtio, oldtio;

if (tcgetattr(fd, &oldtio) != 0)
{
    perror("SetupSerial 1");
    return -1;
}

bzero(&newtio, sizeof(newtio));

//CLOCAL--忽略 modem 控制线,本地连线, 不具数据机控制功能, CREAD--使能接收标志
newtio.c_cflag |= CLOCAL | CREAD;

// 设置数据位数
// 清数据位标志
newtio.c_cflag &= ~CSIZE;

//8 bits
newtio.c_cflag |= CS8;

//设置校验位
//无校验
newtio.c_cflag &= ~PARENB;

// 设置停止位
// 1 stop bit:
newtio.c_cflag &= ~CSTOPB;


// 设置波特率 B2400/B4800/B9600/B19200/B38400/B57600/B115200/B230400
cfsetispeed(&newtio, B115200);
cfsetospeed(&newtio, B115200);

// 设置read读取最小字节数和超时时间
// 读取一个字符等待1*(1/10)s
newtio.c_cc[VTIME] = 1;

// 读取字符的最少个数为1
newtio.c_cc[VMIN] = 1;

tcflush(fd,TCIFLUSH); //清空缓冲区

//激活新设置
if (tcsetattr(fd, TCSANOW, &newtio) != 0)
{
        perror("SetupSerial 3");
        return -1;
}

printf("Serial set done!\n");

return 0;

}

int32_t init_com_port(char* uart_name) { int fdSerial;

    // 打开串口设备
    fdSerial = open(uart_name, O_RDWR | O_NOCTTY | O_NDELAY);
    if(fdSerial < 0)
    {
            perror(uart_name);
            return -1;
    }

    // 设置串口阻塞， 0：阻塞， FNDELAY：非阻塞
    //阻塞，即使前面在open串口设备时设置的是非阻塞的

    if (fcntl(fdSerial, F_SETFL, 0) < 0)
    {
            printf("fcntl failed!\n");
    }
    else
    {
            printf("fcntl=%d\n", fcntl(fdSerial, F_SETFL, 0));
    }

    if (isatty(fdSerial) == 0)
    {
            printf("standard input is not a terminal device\n");
            close(fdSerial);
            return -1;
    }
    else
    {
            printf("is a tty success!\n");
    }
    printf("fd-open=%d\n", fdSerial);

    // 设置串口参数
    if (setOpt(fdSerial)== -1)    //设置8位数据位、1位停止位、无校验
    {
            fprintf(stderr, "Set opt Error\n");
            close(fdSerial);
            exit(1);
    }

    tcflush(fdSerial, TCIOFLUSH);    //清掉串口缓存
    fcntl(fdSerial, F_SETFL, 0);    //串口阻塞


    return fdSerial;

}

---

You can test socat to create Virtual Serial Port doing the following procedure (tested on Ubuntu 12.04):

Open a terminal (let's call it Terminal 0) and execute it:

socat -d -d pty,raw,echo=0 pty,raw,echo=0 The code above returns:

2013/11/01 13:47:27 socat[2506] N PTY is /dev/pts/2 2013/11/01 13:47:27 socat[2506] N PTY is /dev/pts/3 2013/11/01 13:47:27 socat[2506] N starting data transfer loop with FDs [3,3] and [5,5]