Re: [ts-7000] Re: tcgetattr problem

["Don W. Carr" <>]

One quick comment. perror, takes a valid null terminated string, then uses that as part of the error message. It puts that string first, then appends a ':' and space, then the actual error message. So, the code you wrote could potentially crash the program on error.

Use something like this for perror:

perror("Call to tcgetattr");

Now that I think about it, the structure will have the constants that are defined in a header file, which match to a baud rate, but are not the actual baud rate. 

Here is my code for setting, and this should solve the problem for you. You likely need a case statement if you want to print the baud rates, which would be the opposite of what I do below.

  switch (baud_rate)
  {
    case 0:
      rt_tio.c_cflag = B0;
      break;
    case 50:
      rt_tio.c_cflag = B50;
      break;
    case 75:
      rt_tio.c_cflag = B75;
      break;
    case 110:
      rt_tio.c_cflag = B110;
      break;
    case 134:
      rt_tio.c_cflag = B134;
      break;
    case 150:
      rt_tio.c_cflag = B150;
      break;
    case 200:
      rt_tio.c_cflag = B200;
      break;
    case 300:
      rt_tio.c_cflag = B300;
      break;
    case 600:
      rt_tio.c_cflag = B600;
      break;
    case 1200:
      rt_tio.c_cflag = B1200;
      break;
    case 1800:
      rt_tio.c_cflag = B1800;
      break;
    case 2400:
      rt_tio.c_cflag = B2400;
      break;
    case 4800:
      rt_tio.c_cflag = B4800;
    case 9600:
      rt_tio.c_cflag = B9600;
      break;
    case 19200:
      rt_tio.c_cflag = B19200;
      break;
    case 38400:
      rt_tio.c_cflag = B38400;
      break;
    case 57600:
      rt_tio.c_cflag = B57600;
      break;
    case 115200:
      rt_tio.c_cflag = B115200;
      break;
    case 230400:
      rt_tio.c_cflag = B230400;
      break;
    default:
      rt_tio.c_cflag = B9600;
  }
 
I am packing to head for San Francisco, as we speak, so will not be able to reply again, but, I think this will do if for you!!

Don.

On 15 Apr 2007 07:11:44 -0700, Rob <> wrote:

Thanks for the info. It is a serial port because other routines in the program read data off
the GPS if I manually set the baud rate with "stty -F /dev/ttyAM1 speed 19200" (yes this
GPS is not running 4800). The only two routines that fail are configuration and
read_configuration. On your suggestion to check for errors I added

char err_str[256];

result = tcgetattr (file_id, &options);
if(result != 0)
{
printf("Error of %d calling tcgetattr\n", result);
perror(err_str);
}

I get no reported error but the same bad values.

Thanks for the suggestions so far.
Rob

--- In ts-7000%40yahoogroups.com, "Don W. Carr" <> wrote:
>
> First, always check for errors. Capture the return value, and if it is not 0
> (success), then call perror(), to print the error. You must check errors on
> these types of functions and handle them, otherwise, the bigger the program,
> the more likely that you will have mysterious unknown errors at times that
> you can not figure out. For this particular call, you can not call on any
> old fd, it much be a serial port. You might get the error, not a tty or
> something like that as I recall. As I recall, I typically call isatty() to
> check to see if the fd is valid for setting baud rate, before continuing.
>
> Hope that helps!
>
> Don.
>
>
>
>
> --
> Dr. Don W. Carr
> J. G. Montenegro 2258
> Guadalajara, Mexico
> +52-333-630-0704
> +52-333-836-4500 ext 2930
>

-- 
Dr. Don W. Carr
J. G. Montenegro 2258
Guadalajara, Mexico
+52-333-630-0704
+52-333-836-4500 ext 2930

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