Linux下的虛擬串口對（可用於在本機上模擬串口進行調試）

轉載：https://www.cnblogs.com/pengdonglin137/p/4513943.html

今日編寫了一個串口通訊程序，但是本機只有一個串口，無法驗證程序的正確性，於是想到在linux下面增加一對虛擬串口

Python：

#! /usr/bin/env python
#coding=utf-8

import pty
import os
import select

def mkpty():
    # 打開偽終端
    master1, slave = pty.openpty()
    slaveName1 = os.ttyname(slave)
    master2, slave = pty.openpty()
    slaveName2 = os.ttyname(slave)
    print '\nslave device names: ', slaveName1, slaveName2
    return master1, master2

if __name__ == "__main__":

    master1, master2 = mkpty()
    while True:
        rl, wl, el = select.select([master1,master2], [], [], 1)
        for master in rl:
            data = os.read(master, 128)
            print "read %d data." % len(data)
            if master==master1:
                os.write(master2, data)
            else:
                os.write(master1, data)

 

程序名叫mkptych.py，在終端里運行“python mkptych.py &”，這樣就可以生成一個基於pty（偽終端）的虛擬端口對，兩個設備名會顯示在終端里。然后就可以利用這兩個設備名在本機上進行虛擬串口之類的調試，使用完后用ps查看這個python進程的pid號，然后kill掉即可。

下面編寫一個用上述虛擬串口的使用程序：

receiver.c

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <math.h>

#define MAX_BUFFER_SIZE 512

int fd, s;

int open_serial()
{
    //這里的/dev/pts/27是使用mkptych.py虛擬的兩個串口名字之一
    fd = open("/dev/pts/27", O_RDWR|O_NOCTTY|O_NDELAY);
    if(fd == -1)
    {
        perror("open serial port error!\n");
        return -1;
    }

    printf("open /dev/ttyS0.\n");
    return 0;
}

int main()
{
    char hd[MAX_BUFFER_SIZE], *rbuf;
    int flag_close, retv;
    struct termios opt;

    retv = open_serial();
    if(retv < 0)
    {
        printf("Open serrial port error!\n");
        return -1;
    }

    tcgetattr(fd, &opt);
    cfmakeraw(&opt);
    cfsetispeed(&opt, B9600);
    cfsetospeed(&opt, B9600);
    tcsetattr(fd, TCSANOW, &opt);
    rbuf = hd;
    printf("Ready for receiving data...\n");

    while(1)
    {
        while((retv = read(fd, rbuf, 1)) > 0)
            printf( "%c ", *rbuf);
    }

    printf("\n");
    flag_close = close(fd);
    if(flag_close == -1)
        printf("Close the device failure!\n");

    return 0;
}

 

send.c

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>

#define MAX_BUFFER_SIZE 512

int fd, flag_close;

int open_serial()
{
    //這里的/dev/pts/28是使用mkptych.py虛擬的兩個串口名字之一
    fd = open("/dev/pts/28", O_RDWR | O_NOCTTY | O_NONBLOCK);
    if(fd == -1)
    {
        perror("open serial port error!\n");
        return -1;
    }

    printf("Open serial port success!");
    return 0;
}

int main(int argc, char* argv[])
{
    char sbuf[] = {"Hello, this is a serial port test!\n"};
    int retv;
    struct termios option;

    retv = open_serial();
    if(retv < 0)
    {
        perror("open serial port error!\n");
        return -1;
    }

    printf("Ready for sending data...\n");

    tcgetattr(fd, &option);
    cfmakeraw(&option);

    cfsetispeed(&option, B9600);
    cfsetospeed(&option, B9600);

    tcsetattr(fd, TCSANOW, &option);

    int length = sizeof(sbuf);
    retv = write(fd, sbuf, length);
    if(retv == -1)
    {
        perror("Write data error!\n");
        return -1;
    }

    printf("The number of char sent is %d\n", retv);
    return 0;
}

編譯運行即可，呵呵.

 

簡單測試：

echo 123456798 >> /dev/pts/2 這個命令是在linux下發送信息到對端的設備
收的命令很簡單就是 cat /dev/pts/3 你接收的那個串口名。