如何使用 termios.h 配置串行端口以传递原始字节?

问题描述

我需要通过 USB 虚拟串行设备与硬件进行通信.我所需要的只是以正确的 UART 设置以速度来回传递原始字节，我不想使用终端.使用 termios 的概念验证软件没有配置正确的位，除非我在运行之前通过 stty 输入一个神奇的配置字符串，否则它不会工作.

I need to communicate with a piece of hardware over a USB virtual serial device. All I need is it to pass raw bytes back and forth at speed with the right UART settings, I do not ever want to use a terminal. The proof of concept software using termios isn't configuring the right bits and doesn't work unless I feed in a magic config string over stty before running.

我试图从 stty 复制出现在 termios.h 的 POSIX 手册页中的每个设置，但它仍然不起作用，现在屏幕上充满了样板标志设置代码.

I attempted to replicate every setting from stty that appears in the POSIX man page for termios.h and it still doesn't work, and now has a screen full of boilerplate flag setting code.

使用 termios.h 获得无终端串口的最低配置应该是什么?如果有专门针对 Linux 的任何补充，我需要知道这些.

What should be the minimum configuration using termios.h to get a terminal-less serial port? And if there's any additions for Linux specifically I'll need to know those.

推荐答案

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <termios.h>

int serial_open(char *port, int baud)
{
    int fd;
    struct termios tty;
    if((fd = open(port, O_RDWR | O_NOCTTY | O_SYNC)) < 0)
    {
        return -1;
    }

    if(tcgetattr(fd, &tty) < 0)
    {
        return -1;
    }

    cfsetospeed(&tty, (speed_t)baud);
    cfsetispeed(&tty, (speed_t)baud);
    tty.c_cflag |= (CLOCAL | CREAD);
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;
    tty.c_cflag &= ~PARENB;
    tty.c_cflag |= CSTOPB;
    tty.c_cflag &= ~CRTSCTS;
    tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
    tty.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
    tty.c_oflag &= ~OPOST;
    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 1;
    if(tcsetattr(fd, TCSANOW, &tty))
    {
        return -1;
    }

    return fd;
}

/* example usage */
int fd = serial_open("/dev/ttyUSB0", B9600);

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