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 <fcntl.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "wiringSerial.h"

/*
 * serialOpen:
 *	Open and initialise the serial port, setting all the right
 *	port parameters - or as many as are required - hopefully!
 *********************************************************************************
 */

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

  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 ;

    default:
      return -2 ;
  }

  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

  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)
{
    ssize_t bytes_written = write(fd, &c, 1);
    if (bytes_written != 1) {
      perror("Error writing to file descriptor");
    }
}


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

void serialPuts(const int fd, const char *s)
{
    size_t len = strlen(s);
    ssize_t bytes_written = write(fd, s, len);
    if (bytes_written != (ssize_t)len) {
      perror("Error writing to file descriptor");
    }
}

/*
 * 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 ;
}