iPhone serial port communication

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#include <stdio.h>   /* Standard input/output definitions */

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#include <string.h>  /* String function definitions */

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#include <unistd.h>  /* UNIX standard function definitions */

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#include <fcntl.h>   /* File control definitions */

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#include <errno.h>   /* Error number definitions */

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#include <termios.h> /* POSIX terminal control definitions */

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static struct termios gOriginalTTYAttrs;

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010

static int OpenSerialPort()

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{

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intfileDescriptor = -1;

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inthandshake;

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struct termios  options;

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// Open the serial port read/write, with no controlling terminal, and don't wait for a connection.

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// The O_NONBLOCK flag also causes subsequent I/O on the device to be non-blocking.

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// See open(2) ("man 2 open") for details.

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fileDescriptor = open("/dev/tty.iap", O_RDWR | O_NOCTTY | O_NONBLOCK);

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if (fileDescriptor == -1)

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{

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printf("Error opening serial port %s - %s(%d)./n",

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"/dev/tty.iap", strerror(errno), errno);

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goto error;

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}

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// Note that open() follows POSIX semantics: multiple open() calls to the same file will succeed

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// unless the TIOCEXCL ioctl is issued. This will prevent additional opens except by root-owned

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// processes.

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// See tty(4) ("man 4 tty") and ioctl(2) ("man 2 ioctl") for details.

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if (ioctl(fileDescriptor, TIOCEXCL) == -1)

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{

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printf("Error setting TIOCEXCL on %s - %s(%d)./n",

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"/dev/tty.iap", strerror(errno), errno);

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goto error;

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}

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// Now that the device is open, clear the O_NONBLOCK flag so subsequent I/O will block.

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// See fcntl(2) ("man 2 fcntl") for details.

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if (fcntl(fileDescriptor, F_SETFL, 0) == -1)

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{

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printf("Error clearing O_NONBLOCK %s - %s(%d)./n",

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"/dev/tty.iap", strerror(errno), errno);

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goto error;

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}

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// Get the current options and save them so we can restore the default settings later.

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if (tcgetattr(fileDescriptor, &gOriginalTTYAttrs) == -1)

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{

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printf("Error getting tty attributes %s - %s(%d)./n",

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"/dev/tty.iap", strerror(errno), errno);

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goto error;

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}

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// The serial port attributes such as timeouts and baud rate are set by modifying the termios

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// structure and then calling tcsetattr() to cause the changes to take effect. Note that the

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// changes will not become effective without the tcsetattr() call.

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// See tcsetattr(4) ("man 4 tcsetattr") for details.

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options = gOriginalTTYAttrs;

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// Print the current input and output baud rates.

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// See tcsetattr(4) ("man 4 tcsetattr") for details.

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printf("Current input baud rate is %d/n", (int) cfgetispeed(&options));

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printf("Current output baud rate is %d/n", (int) cfgetospeed(&options));

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// Set raw input (non-canonical) mode, with reads blocking until either a single character

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// has been received or a one second timeout expires.

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// See tcsetattr(4) ("man 4 tcsetattr") and termios(4) ("man 4 termios") for details.

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cfmakeraw(&options);

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options.c_cc[VMIN] = 1;

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options.c_cc[VTIME] = 10;

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// The baud rate, word length, and handshake options can be set as follows:

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cfsetspeed(&options, B19200);// Set 19200 baud

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options.c_cflag |= (CS8);  // RTS flow control of input

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printf("Input baud rate changed to %d/n", (int) cfgetispeed(&options));

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printf("Output baud rate changed to %d/n", (int) cfgetospeed(&options));

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// Cause the new options to take effect immediately.

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if (tcsetattr(fileDescriptor, TCSANOW, &options) == -1)

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{

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printf("Error setting tty attributes %s - %s(%d)./n",

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"/dev/tty.iap", strerror(errno), errno);

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goto error;

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}

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// Success

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return fileDescriptor;

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// Failure "/dev/tty.iap"

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error:

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if (fileDescriptor != -1)

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{

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close(fileDescriptor);

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}

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return -1;

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}