serial port flush?

From: Thomas (thomas_at_tho-bai.de)
Date: 01/30/05 

Date: Sun, 30 Jan 2005 03:19:36 +0100

Hi there,

I've written a programme, to communicates with a microcontroller, but
sometimes there is no reaction when I send the initial byte. I'm working
under Suse Linux 9.2 prof. and as I know from a windows programme this
problem shouldn't be caused by the microcontroller. As it always works with
this programme under windows.

So could it be, that when there is a failure at the microcontroller, so that
the byte isn't received (i.e. it isn't in bootstrap mode), that after this
the serial port might be blocked by the previous byte? Or somthing like
that. I know, that this byte cannot really "block" the serial port, but
there must be something that blocks the transfer.

So is there a way to "flush" the serial port before starting a transfer? Or
is it something else that causes my problems.

Hier is my procedure that initializes the serial port:

int openport(char* device)
{
        int fd;
        struct termios options;

        //Stream oeffnen
        fd = open(device, O_RDWR | O_NOCTTY | O_NDELAY);
        
        //ueberpruefen
        if (fd == -1)
                return -1;

        //Alles auf Null setzen
        bzero(&options, sizeof(options));

        //aktuelle Einstellungen holen
        tcgetattr(fd, &options);
        
        //moeglicherweise vorhandene ungewuenschte Einstellungen zuruecksezten
        options.c_cflag &= ~PARENB; //kein Parity-Bit
        options.c_cflag &= ~CSTOPB; //ein Stopbit
        options.c_cflag &= ~CSIZE; //Datenmaske zuruecksetzen
        
        //weitere Controllflags setzen
        options.c_cflag = B19200 | CS8 | CLOCAL | CREAD;
        options.c_iflag = IGNPAR;
        options.c_oflag &= ~OPOST;
        options.c_lflag = 0;
        options.c_cc[VMIN] = 1;
        options.c_cc[VTIME] = 0;

        tcflush(fd, TCIFLUSH);
        tcsetattr(fd, TCSANOW, &options);

        return (fd);
}

So could anybody please help me?

Thanks in advance

Thomas

Relevant Pages

  • Re: serial port flush?
    ... Thomas wrote: ... > under Suse Linux 9.2 prof. and as I know from a windows programme this ... > problem shouldn't be caused by the microcontroller. ... > this the serial port might be blocked by the previous byte? ...
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  • Re: serial port flush?
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