Linux下的虛擬終端（可用於在本機上類比串口進行調試）

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轉載：http://blog.sina.com.cn/s/blog_6cb543ef0100x90j.html

 

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

Python：

#! /usr/bin/env python#coding=utf-8import ptyimport osimport selectdef mkpty():    # 開啟偽終端    master1, slave = pty.openpty()    slaveName1 = os.ttyname(slave)    master2, slave = pty.openpty()    slaveName2 = os.ttyname(slave)    print ‘\nslave device names: ‘, slaveName1, slaveName2    return master1, master2if __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)

 

程式名叫mkptych.py，在終端裡運行“python mkptych.py &”，這樣就可以產生一個基於pty（偽終端）的虛擬連接埠對，兩個裝置名稱會顯示在終端裡。然後就可以利用這兩個裝置名稱在本機上進行虛擬串口之類的調試，使用完後用ps查看這個python進程的pid號，然後kill掉即可。

下面編寫一個用上述虛擬串口的使用程式：

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 512int fd, s;int open_serial(){    //這裡的/dev/pts/27是使用mkptych.py虛擬兩個串口名字之一    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 512int fd, flag_close;int open_serial(){    //這裡的/dev/pts/28是使用mkptych.py虛擬兩個串口名字之一    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.

 

Linux下的虛擬終端（可用於在本機上類比串口進行調試）