Linux USB to serial port

1. Kernel configuration

Device Drivers --->

[*] USB support --->

USB serial converter support --->

<*> USB serial converter support

<*> USB prolific 2303 single port serial driver

 

2. Compile the kernel. Load the kernel on the embedded board. after entering the kernel, check whether the corresponding device node is generated.

# Ls/dev/ttyusb0

If you do not have the above nodes, manually create

# Mknod/dev/ttyusb0 C 188 0

 

3. Write a program to test whether the USB-to-serial port can be read and written normally.

 

Int test_com (char * pcom)
{
Fd_set fds_r;
Struct termios OPT;
Int fdtty0 = 0;
Struct timeval TM = {1, 0 };
Int err = 0;
Char readbuf = '0 ';
Char TMP [16] = {0 };
Char buf1 = 'T ';
Char data1 ='s ';
 
Fdtty0 = open (pcom, o_sync | o_rdwr); // "/dev/ttys2"
If (fdtty0 <0)
{
Printf ("Open % s failed! /N ", pcom );
Goto err;
}
 
If (tcgetattr (fdtty0, & OPT) <0)
Goto err;
 
/* If you uncomment isig and brkint below, then ^ C will be ignored .*/
Opt. c_lflag & = ~ (Echo | icanon | iexten | isig | echoe );
Opt. c_iflag & = ~ (Icrnl | inpck | istrip | ixon | brkint );
Opt. c_iflag & = ~ (Csize | parenb | cstopb );
Opt. c_oflag & = ~ (Onlcr); // For not translate from NL to Cr NL
Opt. c_cflag = cs8 | b115200 | clocal | cread;
Opt. c_cc [Vmin] = 0;
Opt. c_cc [vtime] = 0;

Tcflush (fdtty0, tciflush );
If (tcsetattr (fdtty0, tcsaflush, & OPT) <0)
Goto err;
 
Fd_zero (& fds_r );
Fd_set (fdtty0, & fds_r );

If (write (fdtty0, & buf1, 1) <0)
{
Printf ("Write version error/N ");
Return 0;
}
 
Err = select (fdtty0 + 1, & fds_r, null, null, & TM );
 
If (ERR <0)
{/* Failure */
Printf ("select error/N ");
}
Else if (ERR = 0)
{/* Time Out ;*/
Printf ("select timeout/N ");
}
 
If (fd_isset (fdtty0, & fds_r ))
{
// Err = read (fdtty0, & data1, 1 );

Err = read (fdtty0, TMP, sizeof (TMP ));
Printf ("Err: % d, TMP: % s/n", err, TMP );

If (ERR <0)
{
Printf ("read error/N ");
}
}

Err:
If (fdtty0> 0)
Close (fdtty0 );
Fdtty0 = 0;
 
If (buf1 = TMP [0])
{
Printf ("buf1: % C, TMP [0]: % C, return 1/N", buf1, TMP [0]);
Return 1;
}
Else
{
Printf ("buf1: % C, TMP [0]: % C, return 0/N", buf1, TMP [0]);
Return 0;
}
}