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Saturday 7 January 2012

MBED Example: How to use Arduino TinyGPS library to mbed

.from: http://mbed.org/users/shimniok/libraries/TinyGPS/lqbxxm

XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx TinyGPS.cpp XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx

 /*
  TinyGPS - a small GPS library for Arduino providing basic NMEA parsing
  Copyright (C) 2008-9 Mikal Hart
  All rights reserved.

  This library 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 2.1 of the License, or (at your option) any later version.

  This library 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 this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
  Ported to mbed by Michael Shimniok http://www.bot-thoughts.com/
*/

#include "TinyGPS.h"

#define _GPRMC_TERM   "GPRMC"
#define _GPGGA_TERM   "GPGGA"
#define _GPGSV_TERM   "GPGSV"

TinyGPS::TinyGPS()
:  _time(GPS_INVALID_TIME)
,  _date(GPS_INVALID_DATE)
,  _latitude(GPS_INVALID_ANGLE)
,  _longitude(GPS_INVALID_ANGLE)
,  _altitude(GPS_INVALID_ALTITUDE)
,  _speed(GPS_INVALID_SPEED)
,  _course(GPS_INVALID_ANGLE)
,  _hdop(0)
,  _sat_count(0)
,  _last_time_fix(GPS_INVALID_FIX_TIME)
,  _last_position_fix(GPS_INVALID_FIX_TIME)
,  _parity(0)
,  _is_checksum_term(false)
,  _sentence_type(_GPS_SENTENCE_OTHER)
,  _term_number(0)
,  _term_offset(0)
,  _gps_data_good(false)
,  _rmc_ready(false)
,  _gga_ready(false)
,  _gsv_ready(false)
#ifndef _GPS_NO_STATS
,  _encoded_characters(0)
,  _good_sentences(0)
,  _failed_checksum(0)
#endif
{
  _term[0] = '\0';
}

//
// public methods
//

bool TinyGPS::encode(char c)
{
  bool valid_sentence = false;

  ++_encoded_characters;
  switch(c)
  {
  case ',': // term terminators
    _parity ^= c;
  case '\r':
  case '\n':
  case '*':
    if (_term_offset < sizeof(_term))
    {
      _term[_term_offset] = 0;
      valid_sentence = term_complete();
    }
    ++_term_number;
    _term_offset = 0;
    _is_checksum_term = c == '*';
    return valid_sentence;

  case '$': // sentence begin
    _term_number = _term_offset = 0;
    _parity = 0;
    _sentence_type = _GPS_SENTENCE_OTHER;
    _is_checksum_term = false;
    _gps_data_good = false;
    return valid_sentence;
  }

  // ordinary characters
  if (_term_offset < sizeof(_term) - 1)
    _term[_term_offset++] = c;
  if (!_is_checksum_term)
    _parity ^= c;

  return valid_sentence;
}

#ifndef _GPS_NO_STATS
void TinyGPS::stats(unsigned long *chars, unsigned short *sentences, unsigned short *failed_cs)
{
  if (chars) *chars = _encoded_characters;
  if (sentences) *sentences = _good_sentences;
  if (failed_cs) *failed_cs = _failed_checksum;
}
#endif

//
// internal utilities
//
int TinyGPS::from_hex(char a)
{
  if (a >= 'A' && a <= 'F')
    return a - 'A' + 10;
  else if (a >= 'a' && a <= 'f')
    return a - 'a' + 10;
  else
    return a - '0';
}

unsigned long TinyGPS::parse_decimal()
{
  char *p = _term;
  bool isneg = *p == '-';
  if (isneg) ++p;
  unsigned long ret = 100UL * gpsatol(p);
  while (gpsisdigit(*p)) ++p;
  if (*p == '.')
  {
    if (gpsisdigit(p[1]))
    {
      ret += 10 * (p[1] - '0');
      if (gpsisdigit(p[2]))
        ret += p[2] - '0';
    }
  }
  return isneg ? -ret : ret;
}

unsigned long TinyGPS::parse_degrees()
{
  char *p;
  unsigned long left = gpsatol(_term);
  unsigned long tenk_minutes = (left % 100UL) * 10000UL;
  for (p=_term; gpsisdigit(*p); ++p);
  if (*p == '.')
  {
    unsigned long mult = 1000;
    while (gpsisdigit(*++p))
    {
      tenk_minutes += mult * (*p - '0');
      mult /= 10;
    }
  }
  return (left / 100) * 100000 + tenk_minutes / 6;
}

// Processes a just-completed term
// Returns true if new sentence has just passed checksum test and is validated
bool TinyGPS::term_complete()
{
  if (_is_checksum_term)
  {
    byte checksum = 16 * from_hex(_term[0]) + from_hex(_term[1]);
    if (checksum == _parity)
    {
      if (_gps_data_good)
      {
#ifndef _GPS_NO_STATS
        ++_good_sentences;
#endif
        _last_time_fix = _new_time_fix;
        _last_position_fix = _new_position_fix;

        switch(_sentence_type)
        {
        case _GPS_SENTENCE_GPRMC:
          _time      = _new_time;
          _date      = _new_date;
          _latitude  = _new_latitude;
          _longitude = _new_longitude;
          _speed     = _new_speed;
          _course    = _new_course;
          _rmc_ready = true;
          break;
        case _GPS_SENTENCE_GPGGA:
          _altitude  = _new_altitude;
          _time      = _new_time;
          _latitude  = _new_latitude;
          _longitude = _new_longitude;
          _gga_ready = true;
          _hdop      = _new_hdop;
          _sat_count = _new_sat_count;
        case _GPS_SENTENCE_GPGSV:
          _gsv_ready = true;
          break;
        }

        return true;
      }
    }

#ifndef _GPS_NO_STATS
    else
      ++_failed_checksum;
#endif
    return false;
  }

  // the first term determines the sentence type
  if (_term_number == 0)
  {
    if (!gpsstrcmp(_term, _GPRMC_TERM))
      _sentence_type = _GPS_SENTENCE_GPRMC;
    else if (!gpsstrcmp(_term, _GPGGA_TERM))
      _sentence_type = _GPS_SENTENCE_GPGGA;
    else if (!gpsstrcmp(_term, _GPGSV_TERM))
      _sentence_type = _GPS_SENTENCE_GPGSV;
    else
      _sentence_type = _GPS_SENTENCE_OTHER;
    return false;
  }

  if (_sentence_type != _GPS_SENTENCE_OTHER && _term[0])
  switch((_sentence_type == _GPS_SENTENCE_GPGGA ? 200 : 100) + _term_number)
  {
    case 101: // Time in both sentences
    case 201:
      _new_time = parse_decimal();
      _new_time_fix = millis();
      break;
    case 102: // GPRMC validity
      _gps_data_good = _term[0] == 'A';
      break;
    case 103: // Latitude
    case 202:
      _new_latitude = parse_degrees();
      _new_position_fix = millis();
      break;
    case 104: // N/S
    case 203:
      if (_term[0] == 'S')
        _new_latitude = -_new_latitude;
      break;
    case 105: // Longitude
    case 204:
      _new_longitude = parse_degrees();
      break;
    case 106: // E/W
    case 205:
      if (_term[0] == 'W')
        _new_longitude = -_new_longitude;
      break;
    case 107: // Speed (GPRMC)
      _new_speed = parse_decimal();
      break;
    case 108: // Course (GPRMC)
      _new_course = parse_decimal();
      break;
    case 109: // Date (GPRMC)
      _new_date = gpsatol(_term);
      break;
    case 206: // Fix data (GPGGA)
      _gps_data_good = _term[0] > '0';
      break;
    case 207: // Number of satelites tracked (GPGGA)
      _new_sat_count = parse_decimal();
      break;
    case 208: // Horizontal Dilution of Position (GPGGA)
      _new_hdop = parse_decimal();
      break;
    case 209: // Altitude (GPGGA)
      _new_altitude = parse_decimal();
      break;
  } /* switch */

  return false;
}

long TinyGPS::gpsatol(const char *str)
{
  long ret = 0;
  while (gpsisdigit(*str))
    ret = 10 * ret + *str++ - '0';
  return ret;
}

int TinyGPS::gpsstrcmp(const char *str1, const char *str2)
{
  while (*str1 && *str1 == *str2)
    ++str1, ++str2;
  return *str1;
}


XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx TinyGPS.h XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx

 /*
  TinyGPS - a small GPS library for Arduino providing basic NMEA parsing
  Copyright (C) 2008-9 Mikal Hart
  All rights reserved.

  This library 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 2.1 of the License, or (at your option) any later version.

  This library 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 this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
  Ported to mbed by Michael Shimniok
*/

#include "mbed.h"
#include "types.h"

#ifndef TinyGPS_h
#define TinyGPS_h

#define _GPS_VERSION 9 // software version of this library
#define _GPS_MPH_PER_KNOT 1.15077945
#define _GPS_MPS_PER_KNOT 0.51444444
#define _GPS_KMPH_PER_KNOT 1.852
#define _GPS_MILES_PER_METER 0.00062137112
#define _GPS_KM_PER_METER 0.001
//#define _GPS_NO_STATS

class TinyGPS
{
  public:
 
    /** Create a new GPS parsing object for parsing NMEA sentences
     */
    TinyGPS();
  
    /** Parse a single character received from GPS
     *
     * @param c is the character received from the GPS
     * @returns true if processing ok
     */
    bool encode(char c);
  
    /** Shorthand operator for encode()
     */
    TinyGPS &operator << (char c) {encode(c); return *this;}
  
    /** Return lat/long in hundred thousandths of a degree and age of fix in milliseconds
     * @returns latitude is the latitude of the most recent fix that was parsed
     * @returns longitude is the longitude of the most recent fix that was parsed
     * @returns fix_age is the age of the fix (if available from the NMEA sentences being parsed)
     */
    inline void get_position(long *latitude, long *longitude, unsigned long *fix_age = 0)
    {
      if (latitude) *latitude = _latitude;
      if (longitude) *longitude = _longitude;
      if (fix_age) *fix_age = _last_position_fix == GPS_INVALID_FIX_TIME ?
        GPS_INVALID_AGE : millis() - _last_position_fix;
    }

    /** Return the date and time from the parsed NMEA sentences
     *
     * @returns date as an integer value
     * @returns time as an integer value
     * @returns fix_age in milliseconds if available
     */
    inline void get_datetime(unsigned long *date, unsigned long *time, unsigned long *fix_age = 0)
    {
      if (date) *date = _date;
      if (time) *time = _time;
      if (fix_age) *fix_age = _last_time_fix == GPS_INVALID_FIX_TIME ?
        GPS_INVALID_AGE : millis() - _last_time_fix;
    }

    /** signed altitude in centimeters (from GPGGA sentence)
     * @returns altitude in centimeters, integer
     */
    inline long altitude() { return _altitude; }

    /** course in last full GPRMC sentence in 100th of a degree
     * @returns course as an integer, 100ths of a degree
     */
    inline unsigned long course() { return _course; }
  
    /** speed in last full GPRMC sentence in 100ths of a knot
     * @returns speed in 100ths of a knot
     */
    unsigned long speed() { return _speed; }

    /* horizontal dilution of position in last full GPGGA sentence in 100ths
     * @returns hdop in 100ths
     */
    unsigned long hdop() { return _hdop; }

    /** number of satellites tracked in last full GPGGA sentence
     * @returns number of satellites tracked
     */
    unsigned long sat_count() { return _sat_count; }

#ifndef _GPS_NO_STATS
    void stats(unsigned long *chars, unsigned short *good_sentences, unsigned short *failed_cs);
#endif

    /** returns position as double precision
     *
     * @returns latitude as double precision
     * @returns longitude as double precision
     * @returns fix age in milliseconds if available
     */
    inline void f_get_position(double *latitude, double *longitude, unsigned long *fix_age = 0)
    {
      long lat, lon;
      get_position(&lat, &lon, fix_age);
      *latitude = lat / 100000.0;
      *longitude = lon / 100000.0;
    }

    /** Convert date and time of last parsed sentence to integers
     *
     * @returns year
     * @returns month
     * @returns day of month
     * @returns hour
     * @returns minute
     * @returns second
     * @returns hundreths
     * @returns fix_age in milliseconds if available
     */
    inline void crack_datetime(int *year, byte *month, byte *day,
      byte *hour, byte *minute, byte *second, byte *hundredths = 0, unsigned long *fix_age = 0)
    {
      unsigned long date, time;
      get_datetime(&date, &time, fix_age);
      if (year)
      {
        *year = date % 100;
        *year += *year > 80 ? 1900 : 2000;
      }
      if (month) *month = (date / 100) % 100;
      if (day) *day = date / 10000;
      if (hour) *hour = time / 1000000;
      if (minute) *minute = (time / 10000) % 100;
      if (second) *second = (time / 100) % 100;
      if (hundredths) *hundredths = time % 100;
    }

    /** returns altitude as a float
    */
    inline double f_altitude()    { return altitude() / 100.0; }
  
    /** returns course as a float
    */
    inline double f_course()      { return course() / 100.0; }
  
    /** returns speed in knots as a float
    */
    inline double f_speed_knots() { return speed() / 100.0; }
  
    /** returns speed in mph as a float
    */
    inline double f_speed_mph()   { return _GPS_MPH_PER_KNOT * f_speed_knots(); }
  
    /** returns speed in meters per second as a float
    */
    inline double f_speed_mps()   { return _GPS_MPS_PER_KNOT * f_speed_knots(); }
  
    /** returns speed in km per hour as a float
    */
    inline double f_speed_kmph()  { return _GPS_KMPH_PER_KNOT * f_speed_knots(); }
  
    /** returns hdop as a float
    */
    inline double f_hdop()      { return hdop() / 100.0; }

    /** @returns library version
    */
    static int library_version() { return _GPS_VERSION; }

    /** determine if RMC sentence parsed since last reset_ready()
     */
    inline bool rmc_ready() { return _rmc_ready; }

    /** determine if GGA sentence parsed since last reset_ready()
     */
    inline bool gga_ready() { return _gga_ready; }

    /** determine if GSV sentence parsed since last reset_ready()
     */
    inline bool gsv_ready() { return _gsv_ready; }
  
    /** Reset the ready flags for all the parsed sentences
     */
    inline void reset_ready() { _gsv_ready = _rmc_ready = _gga_ready = false; }

    enum {GPS_INVALID_AGE = 0xFFFFFFFF, GPS_INVALID_ANGLE = 999999999, GPS_INVALID_ALTITUDE = 999999999, GPS_INVALID_DATE = 0,
      GPS_INVALID_TIME = 0xFFFFFFFF, GPS_INVALID_SPEED = 999999999, GPS_INVALID_FIX_TIME = 0xFFFFFFFF};

private:
    enum {_GPS_SENTENCE_GPGGA, _GPS_SENTENCE_GPRMC, _GPS_SENTENCE_GPGSV, _GPS_SENTENCE_OTHER};
  
    // properties
    unsigned long _time, _new_time;
    unsigned long _date, _new_date;
    long _latitude, _new_latitude;
    long _longitude, _new_longitude;
    long _altitude, _new_altitude;
    unsigned long  _speed, _new_speed;
    unsigned long  _course, _new_course;
    unsigned long  _hdop, _new_hdop;
    unsigned int _sat_count, _new_sat_count;
    unsigned long _last_time_fix, _new_time_fix;
    unsigned long _last_position_fix, _new_position_fix;

    // parsing state variables
    byte _parity;
    bool _is_checksum_term;
    char _term[15];
    byte _sentence_type;
    byte _term_number;
    byte _term_offset;
    bool _gps_data_good;
    bool _rmc_ready;
    bool _gga_ready;
    bool _gsv_ready;

#ifndef _GPS_NO_STATS
    // statistics
    unsigned long _encoded_characters;
    unsigned short _good_sentences;
    unsigned short _failed_checksum;
    unsigned short _passed_checksum;
#endif

    // internal utilities
    int from_hex(char a);
    unsigned long parse_decimal();
    unsigned long parse_degrees();
    bool term_complete();
    bool gpsisdigit(char c) { return c >= '0' && c <= '9'; }
    long gpsatol(const char *str);
    int gpsstrcmp(const char *str1, const char *str2);
};

// Arduino 0012 workaround
#undef int
#undef char
#undef long
#undef byte
#undef double
#undef abs
#undef round

#endif


XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx types.h XxXxXxXxXxXxXxXxXxXxXxXxXxXxXxXx

#ifndef __TYPES_H
#define __TYPES_H

typedef char byte;
typedef int millis;

#endif

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