GTK+ Forums

jincy.thomas · Familiar Face Joined: 03 Mar 2010 Posts: 7

I have a GUI application in gtk.

I need to do the data transfer using rs232. I have the terminal gtkterm.

Am defining sCmd in serial port program. Which should print ABC.
char sCmd[254];
sCmd[0] = 0x41;
sCmd[1] = 0x42;
sCmd[2] = 0x43;
sCmd[3] = 0x00;

In the GUI application i want to receive and send the data.

How i need to define the code in GUI.

tadeboro · Posted: Wed Mar 03, 2010 7:01 pm Post subject:

Hello and welcome to the GTK+ forums.

Code you shown has nothing to do with GUI whatsoever. Low level data transfer is done exactly the same whether you're creating command line or GUI application.

Tadej

jincy.thomas · Familiar Face Joined: 03 Mar 2010 Posts: 7

Thanks for the reply.

The exact problem is:

I have a gui. when i click on the button it should transfer data.

For that i have button.
getbutton= gtk_button_new_with_label(" get value");
gtk_widget_set_size_request(getbutton, 80,25);
gtk_fixed_put(GTK_FIXED(frame),getbutton,100, 300);

g_signal_connect(G_OBJECT(getbutton), "clicked",
G_CALLBACK(writeport), NULL);

And in the main:

int main(int argc, char *argv[])
{

gtk_init(&argc, &argv);
displayUI(); //GUI functions creating windows etc.

fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1)
{
perror("open_port: Unable to open /dev/ttyS0 - ");
return 1;
}
else
{
fcntl(fd, F_SETFL, 0);
}

printf("baud=%d\n", getbaud(fd));
initport(fd);
printf("baud=%d\n", getbaud(fd));

char sCmd[254];
sCmd[0] = 0x41;
sCmd[1] = 0x42;
sCmd[2] = 0x43;
sCmd[3] = 0x00;
writeport(fd, sCmd) ;
printf("written:\n", sCmd);
usleep(500000);
char sResult[254];
fcntl(fd, F_SETFL, FNDELAY); // don't block serial read
close(fd);
gtk_main();

return EXIT_SUCCESS;
}

And the writeport function is:

int writeport(int fd, char *chars) {
int len = strlen(chars);
chars[len] = 0x0d;
chars[len+1] = 0x00;
int n = write(fd, chars, strlen(chars));
if (n < 0) {
fputs("write failed!\n", stderr);
return 0;
}
return 1;
}

Now the problem is when i run program, the gui gets displayed. When i click on the getbutton it displays the value "ABC" (this is what the write function sends) and comes out of the window with segmentation fault.

What is wrong exactly? (the serial port communication program works fine without gui)

Thanks in advance..

errol · GTK+ Geek Joined: 28 Apr 2008 Posts: 78 Location: UK

The signal handler for the button click should be in the form of :-

Code: (C)
1	void user_function(GtkButton *button, gpointer user_data)

Your writeport() function is totally different. What should be done is have a signal handler in the above form which then calls your function writeport().