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Eric,=0D
=0D
I've noticed that you initialized fd=3D0. Note that the swich statement h=
as no
default: clause, so calling the function with an out-of-range number (eg =
5),
will skip the open(...)'s and fd will keep as 0. When fd is checked for
error it's compared -1 so it will return success in a wrong situation, ju=
st
after calling the control functions on fd=3D0.=0D
=0D
Isn't a good idea to initialize fd=3D-1?=0D
=0D
Lucas Hartmann=0D
 =0D
-------Mensagem original-------=0D
 =0D
De: pic microcontroller discussion list=0D
Data: 02/16/04 17:45:04=0D
Para: PICLIST@MITVMA.MIT.EDU=0D
Assunto: Re: [EE]: Serial Port and Linux=0D
 =0D
Are you opening the serial port with all the right options?  I've never h=
ad
that=0D
happen, but it sounds like some sort of echo.  Do you know that the devic=
e
you=0D
are reading from is not actually sending the newlines?=0D
 =0D
Here is my serial port initialization function.  You'll need to set the
options=0D
to what you need, but...  Maybe you will find something missing in your c=
ode
=0D
I've used this exact code in several projects over the last year.  Includ=
ing
one=0D
just a few weeks ago, so I know it works.=0D
 =0D
Just pass this function the port number and it returns a file descriptor =
to
the=0D
open port.=0D
 =0D
 =0D
int initialize_serial(int port_num)=0D
{=0D
        struct termios options;=0D
        int fd=3D0;=0D
 =0D
        //open port=0D
        switch(port_num)=0D
        {=0D
                case 0:=0D
                        fd=3Dopen("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDE=
LAY);=0D
                        break;=0D
                case 1:=0D
                        fd=3Dopen("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDE=
LAY);=0D
                        break;=0D
                case 2:=0D
                        fd=3Dopen("/dev/ttyS2", O_RDWR | O_NOCTTY | O_NDE=
LAY);=0D
                        break;=0D
                case 3:=0D
                        fd=3Dopen("/dev/ttyS3", O_RDWR | O_NOCTTY | O_NDE=
LAY);=0D
                        break;=0D
        }=0D
 =0D
        //make sure it opened okay=0D
        if(fd=3D=3D-1)=0D
        {=0D
                printf("Error opening serial port\r\n");=0D
        }=0D
 =0D
        fcntl(fd, F_SETFL, 0);=0D
 =0D
        //get the current port options=0D
        tcgetattr(fd, &options);=0D
 =0D
        //set baud rate=0D
        cfsetispeed(&options, B38400);=0D
        cfsetospeed(&options, B38400);=0D
 =0D
        //set up port for 8N1=0D
        options.c_cflag |=3D (CLOCAL | CREAD);=0D
        options.c_cflag &=3D ~PARENB;=0D
        options.c_cflag &=3D ~CSTOPB;=0D
        options.c_cflag &=3D ~CSIZE;=0D
        options.c_cflag |=3D CS8;=0D
 =0D
        //options.c_lflag |=3D (ICANON);=0D
        options.c_lflag &=3D ~(ECHO | ECHOE | ECHOK | ECHONL | ISIG);=0D
 =0D
        options.c_cc[VTIME]=3D0;=0D
        options.c_cc[VMIN]=3D6;=0D
 =0D
        //apply new settings=0D
        tcsetattr(fd, TCSANOW, &options);=0D
 =0D
        return fd;=0D
}=0D
 =0D
 =0D
 =0D
Good luck,=0D
Eric=0D
 =0D
 =0D
 =0D
On Mon, 16 Feb 2004 15:12:28 -0500=0D
Herbert Graf <mailinglist2@FARCITE.NET> wrote:=0D
 =0D
> Hello all,=0D
>=0D
> I'm trying to write a small program that sends a few things over a seri=
al=0D
> port and then reads a few things back. I've having trouble getting it t=
o=0D
> work.=0D
>=0D
> I'm using open, write and read to do my things, accessing the device
through=0D
> the /dev/ttyS1 interface. Things work fine for a while and then seem to=
 go=0D
> crazy. For example, I can send a few things down the line, but then whe=
n I=0D
> do a single byte read from the port I continuously get the newline=0D
> character.=0D
>=0D
> Anybody have some simple gcc compatible c code of accessing the serial
port=0D
> in Linux? I'm using Redhat 9.0 and gcc. Thanks, TTYL=0D
>=0D
> ----------------------------------=0D
> Herbert's PIC Stuff:=0D
> http://repatch.dyndns.org:8383/pic_stuff/=0D
>=0D
> --=0D
> http://www.piclist.com hint: PICList Posts must start with ONE topic:=0D
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads=0D
 =0D
--=0D
http://www.piclist.com hint: PICList Posts must start with ONE topic:=0D
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads=0D
=20

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