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Cant open serial port properly ... I dont understand whats wrong ...

Discussion in 'Embedded' started by Doublehp, Feb 23, 2004.

  1. Doublehp

    Doublehp Guest

    This message is related with


    I received from motorola the following answer:
    "This customer use Linux and have trouble to send 0x0A or 0x0D, this
    is due
    to his Linux I/O driver. Metrowerks CodeWarrior for HC08 is run under
    Windowes OS and it
    works fine on 908JB8 without any trouble on send 0x0A or 0x0D down."

    can someone untar http://demaine.free.fr/monitor_68hc08/src/ read the
    file rs232.c and try to find whats wrong between lines 49 to 71 ?

    I really dont understand what could make opening the port in a wrong
    mode ...

    You dont really need to comile ... just read my last post, my logbook
    p29 and my source file.

    Thanks for any help
    Doublehp, Feb 23, 2004
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  2. You may need to specify the translation mode as binary, as I'm not sure
    the default translation mode under Linux is.

    Mike Anton
    Michael Anton, Feb 24, 2004
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  3. Doublehp

    Doublehp Guest

    (Doublehp) wrote in message
    after 2h of chat on IRC, someone said me that i forgot to enter
    nonOPOST mode, so I added line 70 with the proper line as described on

    /* canonical raw input */
    vars->serial->c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    vars->serial->c_lflag &= ~OPOST;
    vars->serial->c_cflag |= (CS8); /* use 8bit data */
    // term_prop->c_cflag |= (CLOCAL | CREAD);
    tcsetattr(fd, TCSAFLUSH, vars->serial);

    but I still had the same bug ... so that people offered that very
    horrible hack:
    I put

    sprintf(stty,"stty -a < %s",vars->device);

    after tcsetattr

    Q: why isnt the line with ~OPOST enough ???
    Doublehp, Feb 24, 2004
  4. Doublehp

    Brian Dean Guest

    OPOST needs to be applied to c_oflag (output modes), not c_lflag
    (local modes).

    Brian Dean, Feb 25, 2004
  5. Doublehp

    Doublehp Guest

    You are right. Thank you all of you for your help
    Doublehp, Feb 26, 2004
  6. Doublehp

    Wim Lewis Guest

    Actually, this is setting *non*canonical input (turning off ICANON).
    "Canonical" input means translating the terminal's idea of CR into
    Unix's idea (0x0A). By default, the serial port is configured to
    talk to a terminal, so flags like that are turned on.

    See "man termios" for all the gory details. Yo ucan probably get what
    you want with "raw" mode: call tcgetattr(), cfmakeraw(), and then
    tcsetattr() to apply the modified attributes back onto the serial device.
    cfmakeraw() does almost the same thing you're doing in the code snippet
    you posted, except it modifies a few more flags.
    Wim Lewis, Feb 26, 2004
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