O.K...., Still pretty new to all this...
Below is my modified version of Tiny GPS... Not sure if it's going to work as I've never really dealt with libraries before but I'm happy to give it a go! Any suggestions would be greatly appreciated...
Cheers
Greg.
/*
TinyGPS - a small GPS library for Arduino providing basic NMEA parsing
Copyright (C) 2008-9 Mikal Hart
All rights reserved.
Satellite Count Mod - by Brett Hagman
http://www.roguerobotics.com/
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
*/
#include "WProgram.h"
#include "TinyGPS.h"
#define _GPRMC_TERM "GPRMC"
#define _GPGGA_TERM "GPGGA"
#define _GPGSV_TERM "GPGSV"
#define _GPGSA_TERM "GPGSA"
#define _GPSACP_TERM "GPSACP"
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)
, _satsinview(0)
, _satsused(0)
, _fixtype(GPS_FIX_NO_FIX)
, _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)
#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;
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)
{
#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;
break;
case _GPS_SENTENCE_GPGGA:
_altitude = _new_altitude;
_time = _new_time;
_latitude = _new_latitude;
_longitude = _new_longitude;
break;
case _GPS_SENTENCE_GPGSV:
_satsinview = _new_satsinview;
break;
case _GPS_SENTENCE_GPGSA:
_satsused = _new_satsused;
_fixtype = _new_fixtype;
break;
case _GPS_SENTENCE_GPSACP:
_time = _new_time;
_date = _new_date;
_latitude = _new_latitude;
_longitude = _new_longitude;
_speed = _new_speed;
_course = _new_course;
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 if (!gpsstrcmp(_term, _GPGSA_TERM))
{
_sentence_type = _GPS_SENTENCE_GPGSA;
_new_satsused = 0;
}
else if (!gpsstrcmp(_term, _GPSACP_TERM))
{
_sentence_type = _GPS_SENTENCE_GPSACP;
}
else
_sentence_type = _GPS_SENTENCE_OTHER;
return false;
}
if (_sentence_type == _GPS_SENTENCE_GPGSV)
{
if (_term_number == 3 && _term[0])
{
// we've got our number of sats
// NOTE: we will more than likely hit this a few times in a row, because
// there are usually multiple GPGSV sentences to describe all of the sats
_new_satsinview = (unsigned char) gpsatol(_term);
}
}
else if (_sentence_type == _GPS_SENTENCE_GPGSA)
{
if (_term_number == 2 && _term[0]) // Fix type
{
_new_fixtype = (unsigned char) gpsatol(_term);
}
else if (_term_number >= 3 && _term_number <= 14 && _term[0]) // Count our sats used
{
_new_satsused++;
}
// if (_term_number == 15) // PDOP
// if (_term_number == 16) // HDOP
// if (_term_number == 17) // VDOP
}
else 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 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 209: // Altitude (GPGGA)
_new_altitude = parse_decimal();
break;
}
}
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;
}