Re: need a sample code

From: emb in linux (haranath.t_at_gmail.com)
Date: 11/11/05

  • Next message: emb in linux: "Re: need a sample code" 
    Date: 10 Nov 2005 21:41:11 -0800

    hi
    i am able to read and write a string from and to com-ports and i am
    unable to read a muti strings(sentence).how can i do that?
    thanks in advance.

                                                                     with
    regards
                                                                      emb
    in linux
    Alain Mosnier wrote:
    > Hi,
    >
    > emb in linux wrote:
    > > hai all
    > > This is my first post to this group.I am very much new to embedded
    > > programming .Now i want to write data to com1 and want to read from
    > > com2 .Here i have connected a NULL-MODEM cable in between the two
    > > serial ports.
    > > The following is the code,which i am running on my Linux Box.
    > > I am getting the return value from read as -1.
    >
    > I haven't analyzed your code, but hereafter you will find an example
    > that works for me. I have separated the sending and the receiving parts
    > in two separate processes, each with its own source file and binary. I
    > start the receiving part first, and it receives the character from the
    > sending part when I start it later on.
    >
    > Good luck,
    >
    > Alain
    >
    > Sending part:
    >
    > #include <stdio.h> /* Standard input/output definitions */
    > #include <string.h> /* String function definitions */
    > #include <unistd.h> /* UNIX standard function definitions */
    > #include <fcntl.h> /* File control definitions */
    > #include <errno.h> /* Error number definitions */
    > #include <termios.h> /* POSIX terminal control definitions */
    >
    >
    > int
    > main()
    > {
    > int fd; /* File descriptor for the port */
    > struct termios options;
    >
    > /*
    > * Open the first serial port, read/write, no controlling terminal,
    > * not care about the Data Carrier Detect signal
    > */
    > fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
    > if (fd == -1)
    > {
    > /*
    > * Could not open the port.
    > */
    > perror("Unable to open /dev/ttyS0\n");
    > }
    > else {
    > /*
    > * Set all flags to 0 for the read call to be blocking!???
    > * (according to "Serial Programming Guide for POSIX Operating Systems")
    > */
    > fcntl(fd, F_SETFL, 0);
    >
    > /*
    > * Get the current options for the port...
    > */
    > tcgetattr(fd, &options);
    >
    > /*
    > * Set the baud rates to 115200...
    > */
    > cfsetispeed(&options, B115200);
    > cfsetospeed(&options, B115200);
    >
    > /*
    > * Enable the receiver and set local mode...
    > */
    > options.c_cflag |= (CLOCAL | CREAD);
    >
    > /*
    > * Set the option for 8N1
    > */
    > options.c_cflag &= ~PARENB;
    > options.c_cflag &= ~CSTOPB;
    > options.c_cflag &= ~CSIZE;
    > options.c_cflag |= CS8;
    >
    > /*
    > * Set the option for raw input
    > */
    > options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    >
    > /*
    > * Set the option for raw output
    > */
    > options.c_oflag &= ~OPOST;
    >
    > /*
    > * Set the new options for the port...
    > */
    > tcsetattr(fd, TCSANOW, &options);
    >
    > if (write(fd,"A",1)<0)
    > fprintf(stderr,"Write() of 1 byte failed!\n");
    > close (fd);
    > }
    >
    > return (0);
    > }
    >
    >
    > Receiving part:
    >
    > #include <stdio.h> /* Standard input/output definitions */
    > #include <string.h> /* String function definitions */
    > #include <unistd.h> /* UNIX standard function definitions */
    > #include <fcntl.h> /* File control definitions */
    > #include <errno.h> /* Error number definitions */
    > #include <termios.h> /* POSIX terminal control definitions */
    >
    >
    > int
    > main()
    > {
    > int fd; /* File descriptor for the port */
    > char *c;
    > struct termios options;
    >
    > /*
    > * Open the first serial port, read/write, no controlling terminal,
    > * not care about the Data Carrier Detect signal
    > */
    > fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);
    > if (fd == -1)
    > {
    > /*
    > * Could not open the port.
    > */
    > perror("Unable to open /dev/ttyS1\n");
    > }
    > else {
    > /*
    > * Set all flags to 0 for the read call to be blocking!???
    > * (according to "Serial Programming Guide for POSIX Operating Systems")
    > */
    > fcntl(fd, F_SETFL, 0);
    >
    > /*
    > * Get the current options for the port...
    > */
    > tcgetattr(fd, &options);
    >
    > /*
    > * Set the baud rates to 115200...
    > */
    > cfsetispeed(&options, B115200);
    > cfsetospeed(&options, B115200);
    >
    > /*
    > * Enable the receiver and set local mode...
    > */
    > options.c_cflag |= (CLOCAL | CREAD);
    >
    > /*
    > * Set the option for 8N1
    > */
    > options.c_cflag &= ~PARENB;
    > options.c_cflag &= ~CSTOPB;
    > options.c_cflag &= ~CSIZE;
    > options.c_cflag |= CS8;
    >
    > /*
    > * Set the option for raw input
    > */
    > options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    >
    > /*
    > * Set the option for raw output
    > */
    > options.c_oflag &= ~OPOST;
    >
    > /*
    > * Set the new options for the port...
    > */
    > tcsetattr(fd, TCSANOW, &options);
    >
    > fprintf(stderr,"In server\n");
    > if (read(fd,c,1)<1)
    > fprintf(stderr,"Read() of 1 byte failed!\n");
    > else
    > fprintf(stderr,"Received %c\n",*c);
    > close (fd);
    > }
    >
    > return (0);
    > }
    >
    > /*
    > * seriser
    > * 2005, Alain Mosnier
    > */
    >
    > #include <stdio.h> /* Standard input/output definitions */
    > #include <string.h> /* String function definitions */
    > #include <unistd.h> /* UNIX standard function definitions */
    > #include <fcntl.h> /* File control definitions */
    > #include <errno.h> /* Error number definitions */
    > #include <termios.h> /* POSIX terminal control definitions */
    >
    >
    > int
    > main()
    > {
    > int fd; /* File descriptor for the port */
    > char *c;
    > struct termios options;
    >
    > /*
    > * Open the first serial port, read/write, no controlling terminal,
    > * not care about the Data Carrier Detect signal
    > */
    > fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);
    > if (fd == -1)
    > {
    > /*
    > * Could not open the port.
    > */
    > perror("Unable to open /dev/ttyS1\n");
    > }
    > else {
    > /*
    > * Set all flags to 0 for the read call to be blocking!???
    > * (according to "Serial Programming Guide for POSIX Operating Systems")
    > */
    > fcntl(fd, F_SETFL, 0);
    >
    > /*
    > * Get the current options for the port...
    > */
    > tcgetattr(fd, &options);
    >
    > /*
    > * Set the baud rates to 19200...
    > */
    > cfsetispeed(&options, B115200);
    > cfsetospeed(&options, B115200);
    >
    > /*
    > * Enable the receiver and set local mode...
    > */
    > options.c_cflag |= (CLOCAL | CREAD);
    >
    > /*
    > * Set the option for 8N1
    > */
    > options.c_cflag &= ~PARENB;
    > options.c_cflag &= ~CSTOPB;
    > options.c_cflag &= ~CSIZE;
    > options.c_cflag |= CS8;
    >
    > /*
    > * Set the option for raw input
    > */
    > options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    >
    > /*
    > * Set the option for raw output
    > */
    > options.c_oflag &= ~OPOST;
    >
    > /*
    > * Set the new options for the port...
    > */
    > tcsetattr(fd, TCSANOW, &options);
    >
    > fprintf(stderr,"In server\n");
    > if (read(fd,c,1)<1)
    > fprintf(stderr,"Read() of 1 byte failed!\n");
    > else
    > fprintf(stderr,"Received %c\n",*c);
    > close (fd);
    > }
    >
    > return (0);
    > }

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