File content as of revision 3:ebd79e3acf14:

/* mbed GPS Module Library
 * Copyright (c) 2008-2010, sford
 * Copyright (c) 2013, B.Adryan
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
 
#include "SerialGPS.h"

SerialGPS::SerialGPS(PinName tx, PinName rx, int baud) 
    : 
    _gps_p(new BufferedSerial(tx, rx, baud)),
    _gps(*_gps_p)
{
    this->_gps_p->set_baud(baud);
    this->_UTCtime    = 0.0;
    this->_lat        = 0.0;
    this->_lon        = 0.0;
    this->_lock       = 0;
    this->_fix        = false;
}

SerialGPS::SerialGPS(BufferedSerial* serial)
    :
    _gps_p(serial),
    _gps(*_gps_p)
{
    this->_UTCtime    = 0.0;
    this->_lat        = 0.0;
    this->_lon        = 0.0;
    this->_lock       = 0;
    this->_fix        = false;
}

bool SerialGPS::fix()
{
    return this->_fix;
}

float SerialGPS::get_lat()
{
    return this->_lat;
}

float SerialGPS::get_lon()
{
    return this->_lon;
}

void SerialGPS::send_command(const char* cmd)
{
    this->_gps_p->write(cmd, sizeof(cmd));
}

void SerialGPS::read() 
{
        getline();

        //printf("NMEA sentence: %s\n", this->_nmea);

        // GPRMC sentence: UTC time, status, lat, N/S, lon, E/W, speed, course, date
        if(sscanf(this->_nmea, "GPRMC,%f,%c,%f,%c,%f,%c", &this->_UTCtime, &this->_status, &this->_lat, &this->_NS, &this->_lon, &this->_EW) > 0)
        {
            if(this->_status != 'A')
            {
                this->_fix = false;
            }
            else
            {
                set_vals();
            }
        }
        // GPGGA sentence: UTC time, lat, N/S, lon, E/W, fix indicator
        else if(sscanf(this->_nmea, "GPGGA,%f,%f,%c,%f,%c,%d", &this->_UTCtime, &this->_lat, &this->_NS, &this->_lon, &this->_EW, &this->_lock) > 0)
        {
            if(!this->_lock)
            {
                this->_fix = false;
            }
            else 
            {
                set_vals();
            }
        }
        // GPGLL sentence: lat, N/S, lo, E/W, UTC time, status
        else if(sscanf(this->_nmea, "GPGLL,%f,%c,%f,%c,%f,%c", &this->_lat, &this->_NS, &this->_lon, &this->_EW, &this->_UTCtime, &this->_status) > 0)
        {
            if(this->_status != 'A')
            {
                this->_fix = false;
            }
            else 
            {
                set_vals();
            }
        }
        else
        {
            //printf("No NMEA sentence found");
            this->_fix = false;
        }

    // Clear the NMEA buffer
    strcpy(this->_nmea, "");
}

float SerialGPS::trunc(float v) 
{
    if(v < 0.0) 
    {
        v*= -1.0;
        v = floor(v);
        v*=-1.0;
    } 
    else 
    {
        v = floor(v);
    }
    return v;
}

void SerialGPS::set_vals()
{
    if(this->_NS == 'S') { this->_lat *= -1.0; }
    if(this->_EW == 'W') { this->_lon *= -1.0; }

    float degrees   = trunc(_lat / 100.0f);
    float minutes   = this->_lat *= -1.0;

    this->_lat            = degrees + minutes / 60.0f;
    degrees               = trunc(this->_lon / 100.0f * 0.01f);
    minutes               = this->_lon - (degrees * 100.0f);
    this->_lon            = degrees + minutes / 60.0f;
    this->_fix            = true;
}

void SerialGPS::getline() 
{
    char ch;
    int idx = -1;

    if(!this->_gps_p->readable())
    {
        return;
    }

    // Wait for start of sentence
    while(read_char() != '$');

    // Read from serial one char at a time until max length or read terminal
    while(idx++ <= MAX_LINELENGTH)
    {
        ch = read_char();

        if(ch == '\r')
        {
            break;
        }

        this->_nmea[idx] = ch;
    }
}

char SerialGPS::read_char()
{
    char ch;
    _gps_p->read(&ch, 1);
    return ch;
}