Re: [Gumstix-users] Writing to Serial port

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Hi,

I forgot to add in my  previous mail, that after trying to free the serial 
port (ttyS0), my gumstix does not start automatically anymore. I believe 
that the u-boot bootloader does not run the "boot", "bootm", or "bootd" 
command anymore. Because when I type these from the bootloader I can 
successfully (manually) start my Gumstix. Did anyone have similar problems 
before?

>From: "Joost Meijles" <joo...@ho...>
>Reply-To: "General mailing list for gumstix users." 
><gum...@li...>
>To: gum...@li...
>Subject: Re: [Gumstix-users] Writing to Serial port
>Date: Fri, 08 Jun 2007 09:09:11 +0000
>
>Hi Craig, and Others,
>
>I tried to free the ttyS0, as specified on the gumstix wiki
>(http://docwiki.gumstix.org/Tips_and_tricks). Although after freeing the
>ttyS0 my gumstix does not boot anymore.
>Moreover, when monitoring the output written to the ttyS0 I do not see any
>messages that could bother my protocol. Could it be that the switching of
>parity goes wrong? Or does anyone know what I could do more to fix this?
>
>
>Kind regards,
>
>Joost
>
>
> >From: Craig Hughes <cr...@gu...>
> >Reply-To: "General mailing list for gumstix users."
> ><gum...@li...>
> >To: "General mailing list for gumstix users."
> ><gum...@li...>
> >Subject: Re: [Gumstix-users] Writing to Serial port
> >Date: Thu, 7 Jun 2007 08:03:46 -0700
> >
> >Joost,
> >
> >did you disable console output to /dev/ttyS0?  If not, then the
> >console messages which the kernel writes to /dev/ttyS0 might be
> >messing with your serial comms protocol...
> >
> >C
> >
> >On Jun 7, 2007, at 7:51 AM, Joost Meijles wrote:
> >
> > > Hi All,
> > >
> > > I am trying to write something to the serial port of the gumstix
> > > (the serial
> > > port is located on the tweener expansion board). First I connected the
> > > gumstix to my PC via serial. When doing this I listen on the PC
> > > side what is
> > > written to serial port on the Gumstix side. This seems to work
> > > correctly
> > > (since I am writing bytes, some characters do not appear on the
> > > screen).
> > > However, when connecting the device I want to control to the
> > > Gumstix it does
> > > not work correctly. Now is the case that for the device I want to
> > > control a
> > > specific protocol is needed. The key element in this protocol is to
> > > switch
> > > from "space" to "mark" parity and vice-versa. Please see the code
> > > below
> > > where I do the setup in the first snippet, and I do the switching
> > > of parity
> > > in the second snippet.
> > >
> > > My feeling says that something goes wrong when cross-compiling the
> > > code to
> > > the Gumstix hardware.
> > > Since the same code is working fine on my PC Linux machine (i.e. I can
> > > successfully control the device). Does anyone have experience with
> > > this? Or
> > > can anyone give me a clue were to look? Maybe someone experienced
> > > problems
> > > with "termios.h" before?
> > >
> > > Thanks a lot in advance.
> > >
> > >
> > > Kind regards,
> > >
> > > Joost Meijles
> > > PS. Reading from the serial port goes fine.
> > >
> > > ================SETUP============
> > > int fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
> > > 	tcflush(fd, TCIOFLUSH);
> > > 	debug("serial port open");
> > > 	//configure the serial port
> > > 	struct termios options;
> > >
> > > 	if(tcgetattr(fd, &options) < 0)		// READ SETTINGS
> > > 	{
> > > 		debug("error getting serial port configuration");
> > > 	}
> > >
> > > 	cfmakeraw(&options);
> > > 	cfsetospeed(&options, B115200);			// SET SPEED
> > > 	cfsetispeed(&options, B115200);
> > >
> > > 	options.c_iflag &= ~CLOCAL;				// Set ...
> > > 	options.c_cflag |= CLOCAL;
> > > 	options.c_iflag &= ~CREAD;
> > > 	options.c_cflag |= CREAD;
> > >
> > > 	options.c_iflag &= ~CSTOPB;				// SET STOPBITS
> > >
> > > 	options.c_iflag &= ~PARENB;				// SET PARITY BITS
> > > 	options.c_iflag &= ~PARODD;
> > >
> > > 	// Odd
> > > 	options.c_cflag |= PARENB;
> > > 	options.c_cflag |= PARODD;
> > >
> > >
> > > 	options.c_iflag &= ~CS5;				// SET DATABITS
> > > 	options.c_iflag &= ~CS6;
> > > 	options.c_iflag &= ~CS7;
> > > 	options.c_iflag &= ~CS8;
> > >
> > > 	// 8 databits
> > > 	options.c_cflag |= CS8;
> > >
> > > 	options.c_cflag &= ~CRTSCTS;			// SET HARDWARE FLOW CONTROL to none
> > >
> > >
> > > 	if(tcsetattr(fd, TCSANOW, &options) < 0)	// WRITE SETTINGS
> > > 	{
> > > 		debug("error writing configuration to serial port");
> > > 	}
> > > ===========================================
> > >
> > > ===============SWITCH=====================
> > > //switch the parity for writing
> > > 	tcgetattr(fd, &options);//get the configuration
> > > 	options.c_cflag &= ~PARENB;
> > > 	options.c_cflag &= ~PARODD;
> > > 	options.c_cflag |= PARENB | 010000000000;
> > > 	options.c_cflag &= ~PARODD;
> > > 	if(tcsetattr(fd, TCSAFLUSH, &options) < 0) {//set the configuration
> > > 		debug("error writing configuration to serial port");
> > > 	}
> > > ============================================
> > >
> > > _________________________________________________________________
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