WiringPi/wiringPi/wiringSerial.c

/*
 * wiringSerial.c:
 *	Handle a serial port
 ***********************************************************************
 * This file is part of wiringPi:
 *	https://github.com/WiringPi/WiringPi/
 *
 *    wiringPi is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    wiringPi is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the GNU Lesser General Public License
 *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
 ***********************************************************************
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "wiringSerial.h"

/*
 * serialOpen:
 *	Open and initialise the serial port, setting port parameters
 *********************************************************************************
 */

int serialOpen (const char *device, const int baud)
{
  struct termios options;
  speed_t myBaud;
  int     status, fd;
  int regularFile = 0;

  switch (baud)
  {
    case      50:	myBaud =      B50; break;
    case      75:	myBaud =      B75; break;
    case     110:	myBaud =     B110; break;
    case     134:	myBaud =     B134; break;
    case     150:	myBaud =     B150; break;
    case     200:	myBaud =     B200; break;
    case     300:	myBaud =     B300; break;
    case     600:	myBaud =     B600; break;
    case    1200:	myBaud =    B1200; break;
    case    1800:	myBaud =    B1800; break;
    case    2400:	myBaud =    B2400; break;
    case    4800:	myBaud =    B4800; break;
    case    9600:	myBaud =    B9600; break;
    case   19200:	myBaud =   B19200; break;
    case   38400:	myBaud =   B38400; break;
    case   57600:	myBaud =   B57600; break;
    case  115200:	myBaud =  B115200; break;
    case  230400:	myBaud =  B230400; break;
    case  460800:	myBaud =  B460800; break;
    case  500000:	myBaud =  B500000; break;
    case  576000:	myBaud =  B576000; break;
    case  921600:	myBaud =  B921600; break;
    case 1000000:	myBaud = B1000000; break;
    case 1152000:	myBaud = B1152000; break;
    case 1500000:	myBaud = B1500000; break;
    case 2000000:	myBaud = B2000000; break;
    case 2500000:	myBaud = B2500000; break;
    case 3000000:	myBaud = B3000000; break;
    case 3500000:	myBaud = B3500000; break;
    case 4000000:	myBaud = B4000000; break;

    // Undocumented: If baud is -1, treat device as a regular file!
    case -1: myBaud = B115200; regularFile = 1; break;

    default:
      return -2;
  }

  if (!regularFile)
  {
    if ((fd = open (device, O_RDWR | O_NOCTTY | O_NDELAY | O_NONBLOCK)) == -1)
      return -1;

    fcntl (fd, F_SETFL, O_RDWR);

    // Get and modify current options:

    tcgetattr (fd, &options);

      cfmakeraw   (&options);
      cfsetispeed (&options, myBaud);
      cfsetospeed (&options, myBaud);

      options.c_cflag |= (CLOCAL | CREAD);
      options.c_cflag &= ~PARENB;
      options.c_cflag &= ~CSTOPB;
      options.c_cflag &= ~CSIZE;
      options.c_cflag |= CS8;
      options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
      options.c_oflag &= ~OPOST;

      options.c_cc [VMIN]  =   0;
      options.c_cc [VTIME] = 100;	// Ten seconds (100 deciseconds)

    tcsetattr (fd, TCSANOW, &options);

    ioctl (fd, TIOCMGET, &status);

    status |= TIOCM_DTR;
    status |= TIOCM_RTS;

    ioctl (fd, TIOCMSET, &status);

    usleep (10000);	// 10mS
  }
  else
  {
    // Want to open a regular file
    if ((fd = open (device, O_RDWR | O_CREAT, 0666)) == -1)
      return -1;
  }

  return fd;
}


/*
 * serialFlush:
 *	Flush the serial buffers (both tx & rx)
 *********************************************************************************
 */

void serialFlush (const int fd)
{
  tcflush (fd, TCIOFLUSH);
}


/*
 * serialClose:
 *	Release the serial port
 *********************************************************************************
 */

void serialClose (const int fd)
{
  close (fd);
}


/*
 * serialPutchar:
 *	Send a single character to the serial port
 *********************************************************************************
 */

void serialPutchar (const int fd, const unsigned char c)
{
  write (fd, &c, 1);
}


/*
 * serialPuts:
 *	Send a string to the serial port
 *********************************************************************************
 */

void serialPuts (const int fd, const char *s)
{
  write (fd, s, strlen (s));
}

/*
 * serialPrintf:
 *	Printf over Serial
 *********************************************************************************
 */

void serialPrintf (const int fd, const char *message, ...)
{
  va_list argp;
  char buffer [1024];

  va_start (argp, message);
    vsnprintf (buffer, 1023, message, argp);
  va_end (argp);

  serialPuts (fd, buffer);
}


/*
 * serialDataAvail:
 *	Return the number of bytes of data avalable to be read in the serial port
 *********************************************************************************
 */

int serialDataAvail (const int fd)
{
  int result;

  if (ioctl (fd, FIONREAD, &result) == -1)
    return -1;

  return result;
}


/*
 * serialGetchar:
 *	Get a single character from the serial device.
 *	Note: Zero is a valid character and this function will time-out after
 *	10 seconds.
 *********************************************************************************
 */

int serialGetchar (const int fd)
{
  uint8_t x;

  if (read (fd, &x, 1) != 1)
    return -1;

  return ((int)x) & 0xFF;
}