[Gumstix-users] serial port problems, ttyS2 waysmall STUART

[chris r. <cr...@wh...>]

Hi,

I have a Basix and a STUART waysmall.  I can't get /dev/ttyS2 to
work when using a C program.  I can do at the prompt ...
#stty -F /dev/ttyS2
   speed 9600 baud;
    -brkint -imaxbel
#echo "foobar" > /dev/ttyS2

and have foobar show up on another computer.  then doing....

# cat /proc/tty/driver/PXA\ serial
2: uart:STUART mmio:0x40700000 irq:13 tx:89 rx:0

verifies that character were actually sent.  the only odd thing is that
the echo will send the characters and then hang the prompt for about
30 seconds ????

BUT, if i write a simple C program, (at the end of the email), i can't
get anything so show up on the other machine.  in fact, the characters
show up on the console, ttyS0.  Doing # cat /proc/tty/driver/PXA\ serial
after running the C-program verifies that nothing was sent out.
I can however using the "system" command from in the C
program and get it to work fine, with the 30 second hang up.

So, whats the deal??????????

in the code below, i get a correct >0 integer value for the file 
descriptor and
write, returns the current number of characters sent, that end up on 
ttyS0 instead
of ttyS2.

Thanks

- Chris



The C-code

/*--------------------------------------------------------------------*/
#include "sampler.h"
#include "sampler_util.h"

void main()
{
  char cmd_string[128];
  unsigned char serial_cmd[128] = {'\0'};
  int fd,num_sent;

   printf("Hello, small world!\n");
  
  //set up the serial port
  fd = set_port_cmu();
  printf("fd=%d, %s\n",fd,PORT);
  tcflush(fd,TCIFLUSH);

  //make and send a string
  sprintf(serial_cmd,"serial_testing");
  num_sent = write(fd,serial_cmd,10);
  printf("num_sent %d\n",num_sent);

  //this works using the system cmd
  sprintf(cmd_string,"echo \"serial_test_system\" > /dev/ttyS2");
  printf("%s\n",cmd_string);
  system(cmd_string);

  //close serial port
  close(fd);
}
/*--------------------------------------------------------------------*/

AND an h file

*--------------------------------------------------------------------*/
#include "sampler.h"
/* Defines */
#define BAUDRATE B9600
#define PORT "/dev/ttyS2"
#define FALSE 0
#define TRUE 1
extern int set_port();
extern int set_port_cmu();
*--------------------------------------------------------------------*/

AND the port opening stuff


*--------------------------------------------------------------------*/
int set_port_cmu() {
    struct termios serial_opts;
    int fd;

    fd = open(PORT, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        perror(PORT);
        return -1;
    }
    else
        fcntl(fd, F_SETFL, FNDELAY);

    tcgetattr(fd, &serial_opts);

    // set baud rate
    cfsetispeed(&serial_opts, BAUDRATE);
    cfsetospeed(&serial_opts, BAUDRATE);

    // enable receiver mode and set local mode
    serial_opts.c_cflag |= (CLOCAL | CREAD);

    // set 8n1
    serial_opts.c_cflag &= ~PARENB;
    serial_opts.c_cflag &= ~CSTOPB;
    serial_opts.c_cflag &= ~CSIZE;
    serial_opts.c_cflag |= CS8;

    // disable hardware control
    serial_opts.c_cflag &= ~CRTSCTS;

    // raw input
    serial_opts.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG) | (ECHOCTL | 
ECHOPRT);

    // set the options
    tcsetattr(fd, TCSANOW, &serial_opts);

    return(fd);
}
*--------------------------------------------------------------------*/











-- 

=======================================
Chris Roman, Ph.D.

Woods Hole Oceanographic Institution
Deep Submergence Laboratory 

cr...@wh...
Phone 508-289-2652
Fax 508-457-2191

http://www.whoi.edu/people/croman
=======================================