/* trackuino copyright (C) 2010  EA5HAV Javi

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 */

#ifndef __CONFIG_H__

#define __CONFIG_H__

// --------------------------------------------------------------------------

// THIS IS THE TRACKUINO FIRMWARE CONFIGURATION FILE. YOUR CALLSIGN AND

// OTHER SETTINGS GO HERE.

//

// NOTE: all pins are Arduino based, not the Atmega chip. Mapping:

// http://www.arduino.cc/en/Hacking/PinMapping

// --------------------------------------------------------------------------

// --------------------------------------------------------------------------

// APRS config (aprs.c)

// --------------------------------------------------------------------------

// Set your callsign and SSID here. Common values for the SSID are

// (from http://zlhams.wikidot.com/aprs-ssidguide):

//

// - Balloons:  11

// - Cars:       9

// - Home:       0

// - IGate:      5

#define S_CALLSIGN      "MYCALL"

#define S_CALLSIGN_ID   11

// Destination callsign: APRS (with SSID=0) is usually okay.

#define D_CALLSIGN      "APRS"

#define D_CALLSIGN_ID   0

// Digipeating paths:

// (read more about digipeating paths here: http://wa8lmf.net/DigiPaths/ )

// The recommended digi path for a balloon is WIDE2-1 or pathless. The default

// is pathless. Uncomment the following two lines for WIDE2-1 path:

#define DIGI_PATH1      "WIDE2"

#define DIGI_PATH1_TTL  1

// APRS comment: this goes in the comment portion of the APRS message. You

// might want to keep this short. The longer the packet, the more vulnerable

// it is to noise. 

#define APRS_COMMENT    "Trackuino reminder: replace callsign with your own"

// --------------------------------------------------------------------------

// AX.25 config (ax25.cpp)

// --------------------------------------------------------------------------

// TX delay in milliseconds

#define TX_DELAY      300

// --------------------------------------------------------------------------

// Tracker config (trackuino.pde)

// --------------------------------------------------------------------------

// APRS packets are slotted so that multiple trackers can be used without

// them stepping on one another. The transmission times are governed by

// the formula:

//

//         APRS_SLOT (seconds) + n * APRS_PERIOD (seconds)

//

// When launching multiple balloons, use the same APRS_PERIOD in all balloons

// and set APRS_SLOT so that the packets are spaced equally in time.

// Eg. for two balloons and APRS_PERIOD = 60, set APRS_SLOT to 0 and 30, 

// respectively. The first balloon will transmit at 00:00:00, 00:01:00, 

// 00:02:00, etc. amd the second balloon will transmit at 00:00:30, 00:01:30,

// 00:02:30, etc.

#define APRS_SLOT     0     // seconds. -1 disables slotted transmissions

#define APRS_PERIOD   60    // seconds

// GPS baud rate (in bits per second). This is also the baud rate at which

// debug data will be printed out the serial port.

#define GPS_BAUDRATE  9600

// --------------------------------------------------------------------------

// Modem config (afsk.cpp)

// --------------------------------------------------------------------------

// AUDIO_PIN is the audio-out pin. The audio is generated by timer 2 using

// PWM, so the only two options are pins 3 and 11.

// Pin 11 doubles as MOSI, so I suggest using pin 3 for PWM and leave 11 free

// in case you ever want to interface with an SPI device.

#define AUDIO_PIN       3

// --------------------------------------------------------------------------

// Radio config (radio_hx1.cpp)

// --------------------------------------------------------------------------

// This is the PTT pin

#define PTT_PIN           4

// --------------------------------------------------------------------------

// Sensors config (sensors.cpp)

// --------------------------------------------------------------------------

// Most of the sensors.cpp functions use internal reference voltages (either

// AVCC or 1.1V). If you want to use an external reference, you should

// uncomment the following line:

//

// #define USE_AREF

//

// BEWARE! If you hook up an external voltage to the AREF pin and 

// accidentally set the ADC to any of the internal references, YOU WILL

// FRY YOUR AVR.

//

// It is always advised to connect the AREF pin through a pull-up resistor,

// whose value is defined here in ohms (set to 0 if no pull-up):

//

#define AREF_PULLUP           4700

//

// Since there is already a 32K resistor at the ADC pin, the actual

// voltage read will be VREF * 32 / (32 + AREF_PULLUP)

//

// Read more in the Arduino reference docs:

// http://arduino.cc/en/Reference/AnalogReference?from=Reference.AREF

// Pin mappings for the internal / external temperature sensors. VS refers

// to (arduino) digital pins, whereas VOUT refers to (arduino) analog pins.

#define INTERNAL_LM60_VS_PIN     6

#define INTERNAL_LM60_VOUT_PIN   0

#define EXTERNAL_LM60_VS_PIN     7

#define EXTERNAL_LM60_VOUT_PIN   1

// Units for temperature sensors (Added by: Kyle Crockett)

// 1 = Celsius, 2 = Kelvin, 3 = Fahrenheit

#define TEMP_UNIT 1

// Calibration value in the units selected. Use integer only.

#define CALIBRATION_VAL 0

// Resistors divider for the voltage meter (ohms)

#define VMETER_R1       10000

#define VMETER_R2       3300

// Voltage meter analog pin

#define VMETER_PIN      2

// --------------------------------------------------------------------------

// Buzzer config (buzzer.cpp)

// --------------------------------------------------------------------------

// Type of buzzer (0=active, 1=passive). An active buzzer is driven by a

// DC voltage. A passive buzzer needs a PWM signal.

#define BUZZER_TYPE             0

// When using a passive buzzer, specify the PWM frequency here. Choose one

// that maximizes the volume according to the buzzer's datasheet. Not all

// the frequencies are valid, check out the buzzer_*.cpp code. On Arduino,

// it must be between L and 65535, where L = F_CPU / 65535 and F_CPU is the

// clock rate in hertzs. For 16 MHz Arduinos, this gives a lower limit of 

// 245 Hz.

#define BUZZER_FREQ             895     // Hz

// These are the number of seconds the buzzer will stay on/off alternately

#define BUZZER_ON_TIME          1       // secs

#define BUZZER_OFF_TIME         2       // secs

// This option disables the buzzer above BUZZER_ALTITUDE meters. This is a

// float value, so make it really high (eg. 1000000.0 = 1 million meters)

// if you want it to never stop buzzing.

#define BUZZER_ALTITUDE         3000.0  // meters (1 ft = 0.3048 m)

// The options here are pin 9 or 10

#define BUZZER_PIN              9

// --------------------------------------------------------------------------

// Debug

// --------------------------------------------------------------------------

// This is the LED pin (13 on Arduinos). The LED will be on while the AVR is

// running and off while it's sleeping, so its brightness gives an indication

// of the CPU activity.

#define LED_PIN                 13

// Debug info includes printouts from different modules to aid in testing and

// debugging.

// 

// 1. To properly receive debug information, only connect the Arduino RX pin 

//    to the GPS TX pin, and leave the Arduino TX pin disconnected. 

//

// 2. On the serial monitor, set the baudrate to GPS_BAUDRATE (above),

//    usually 9600.

//

// 3. When flashing the firmware, disconnect the GPS from the RX pin or you

//    will get errors.

// #define DEBUG_GPS    // GPS sentence dump and checksum validation

// #define DEBUG_AX25   // AX.25 frame dump

// #define DEBUG_MODEM  // Modem ISR overrun and profiling

// #define DEBUG_RESET  // AVR reset

// #define DEBUG_SENS   // Sensors

#endif

/* trackuino copyright (C) 2010  EA5HAV Javi

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 */

#include "config.h"

#include "gps.h"

#include <stdlib.h>

#include <string.h>

// Module declarations

static void parse_sentence_type(const char * token);

static void parse_time(const char *token);

static void parse_status(const char *token);

static void parse_lat(const char *token);

static void parse_lat_hemi(const char *token);

static void parse_lon(const char *token);

static void parse_lon_hemi(const char *token);

static void parse_speed(const char *token);

static void parse_course(const char *token);

static void parse_altitude(const char *token);

// Module types

typedef void (*t_nmea_parser)(const char *token);

enum t_sentence_type {

  SENTENCE_UNK,

  SENTENCE_GGA,

  SENTENCE_RMC

};

// Module constants

static const t_nmea_parser unk_parsers[] = {

  parse_sentence_type,    // $GPxxx

};

static const t_nmea_parser gga_parsers[] = {

  NULL,             // $GPGGA

  parse_time,       // Time

  NULL,             // Latitude

  NULL,             // N/S

  NULL,             // Longitude

  NULL,             // E/W

  NULL,             // Fix quality 

  NULL,             // Number of satellites

  NULL,             // Horizontal dilution of position

  parse_altitude,   // Altitude

  NULL,             // "M" (mean sea level)

  NULL,             // Height of GEOID (MSL) above WGS84 ellipsoid

  NULL,             // "M" (mean sea level)

  NULL,             // Time in seconds since the last DGPS update

  NULL              // DGPS station ID number

};

static const t_nmea_parser rmc_parsers[] = {

  NULL,             // $GPRMC

  parse_time,       // Time

  parse_status,     // A=active, V=void

  parse_lat,        // Latitude,

  parse_lat_hemi,   // N/S

  parse_lon,        // Longitude

  parse_lon_hemi,   // E/W

  parse_speed,      // Speed over ground in knots

  parse_course,     // Track angle in degrees (true)

  NULL,             // Date (DDMMYY)

  NULL,             // Magnetic variation

  NULL              // E/W

};

static const int NUM_OF_UNK_PARSERS = (sizeof(unk_parsers) / sizeof(t_nmea_parser));

static const int NUM_OF_GGA_PARSERS = (sizeof(gga_parsers) / sizeof(t_nmea_parser));

static const int NUM_OF_RMC_PARSERS = (sizeof(rmc_parsers) / sizeof(t_nmea_parser));

// Module variables

static t_sentence_type sentence_type = SENTENCE_UNK;

static bool at_checksum = false;

static unsigned char our_checksum = '$';

static unsigned char their_checksum = 0;

static char token[16];

static int num_tokens = 0;

static unsigned int offset = 0;

static bool active = false;

static char gga_time[7] = "", rmc_time[7] = "";

static char new_time[7];

static uint32_t new_seconds;

static float new_lat;

static float new_lon;

static char new_aprs_lat[9];

static char new_aprs_lon[10];

static float new_course;

static float new_speed;

static float new_altitude;

// Public (extern) variables, readable from other modules

char gps_time[7];       // HHMMSS

uint32_t gps_seconds = 0;   // seconds after midnight

float gps_lat = 0;

float gps_lon = 0;

char gps_aprs_lat[9];

char gps_aprs_lon[10];

float gps_course = 0;

float gps_speed = 0;

float gps_altitude = 0;

// Module functions

unsigned char from_hex(char a) 

{

  if (a >= 'A' && a <= 'F')

    return a - 'A' + 10;

  else if (a >= 'a' && a <= 'f')

    return a - 'a' + 10;

  else if (a >= '0' && a <= '9')

    return a - '0';

  else

    return 0;

}

void parse_sentence_type(const char *token)

{

  if (strcmp(token, "$GPGGA") == 0) {

    sentence_type = SENTENCE_GGA;

  } else if (strcmp(token, "$GPRMC") == 0) {

    sentence_type = SENTENCE_RMC;

  } else {

    sentence_type = SENTENCE_UNK;

  }

}

void parse_time(const char *token)

{

  // Time can have decimals (fractions of a second), but we only take HHMMSS

  strncpy(new_time, token, 6);

  // Terminate string

  new_time[6] = '\0';

  new_seconds = 

    ((new_time[0] - '0') * 10 + (new_time[1] - '0')) * 60 * 60UL +

    ((new_time[2] - '0') * 10 + (new_time[3] - '0')) * 60 +

    ((new_time[4] - '0') * 10 + (new_time[5] - '0'));

}

void parse_status(const char *token)

{

  // "A" = active, "V" = void. We shoud disregard void sentences

  if (strcmp(token, "A") == 0)

    active = true;

  else

    active = false;

}

void parse_lat(const char *token)

{

  // Parses latitude in the format "DD" + "MM" (+ ".M{...}M")

  char degs[3];

  if (strlen(token) >= 4) {

    degs[0] = token[0];

    degs[1] = token[1];

    degs[2] = '\0';

    new_lat = atof(degs) + atof(token + 2) / 60;

  }

  // APRS-ready latitude

  strncpy(new_aprs_lat, token, 7);

  new_aprs_lat[7] = '\0';

}

void parse_lat_hemi(const char *token)

{

  if (token[0] == 'S')

    new_lat = -new_lat;

  new_aprs_lat[7] = token[0];

  new_aprs_lon[8] = '\0';

}

void parse_lon(const char *token)

{

  // Longitude is in the format "DDD" + "MM" (+ ".M{...}M")

  char degs[4];

  if (strlen(token) >= 5) {

    degs[0] = token[0];

    degs[1] = token[1];

    degs[2] = token[2];

    degs[3] = '\0';

    new_lon = atof(degs) + atof(token + 3) / 60;

  }

  // APRS-ready longitude

  strncpy(new_aprs_lon, token, 8);

  new_aprs_lon[8] = '\0';

}

void parse_lon_hemi(const char *token)

{

  if (token[0] == 'W')

    new_lon = -new_lon;

  new_aprs_lon[8] = token[0];

  new_aprs_lon[9] = '\0';

}

void parse_speed(const char *token)

{

  new_speed = atof(token);

}

void parse_course(const char *token)

{

  new_course = atof(token);

}

void parse_altitude(const char *token)

{

  new_altitude = atof(token);

}

//

// Exported functions

//

void gps_setup() {

  strcpy(gps_time, "000000");

  strcpy(gps_aprs_lat, "0000.00N");

  strcpy(gps_aprs_lon, "00000.00E");

}

bool gps_decode(char c)

{

  int ret = false;

  switch(c) {

    case '\r':

    case '\n':

      // End of sentence

      if (num_tokens && our_checksum == their_checksum) {

#ifdef DEBUG_GPS

        Serial.print(" (OK!) ");

        Serial.print(millis());

#endif

        // Return a valid position only when we've got two rmc and gga

        // messages with the same timestamp.

        switch (sentence_type) {

          case SENTENCE_UNK:

            break;    // Keeps gcc happy

          case SENTENCE_GGA:

            strcpy(gga_time, new_time);

            break;

          case SENTENCE_RMC:

            strcpy(rmc_time, new_time);

            break;

        }

        // Valid position scenario:

        //

        // 1. The timestamps of the two previous GGA/RMC sentences must match.

        //

        // 2. We just processed a known (GGA/RMC) sentence. Suppose the

        //    contrary: after starting up this module, gga_time and rmc_time

        //    are both equal (they're both initialized to ""), so (1) holds

        //    and we wrongly report a valid position.

        //

        // 3. The GPS has a valid fix. For some reason, the Venus 634FLPX

        //    reports 24 deg N, 121 deg E (the middle of Taiwan) until a valid

        //    fix is acquired:

        //

        //    $GPGGA,120003.000,2400.0000,N,12100.0000,E,0,00,0.0,0.0,M,0.0,M,,0000*69 (OK!)

        //    $GPGSA,A,1,,,,,,,,,,,,,0.0,0.0,0.0*30 (OK!)

        //    $GPRMC,120003.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*78 (OK!)

        //    $GPVTG,000.0,T,,M,000.0,N,000.0,K,N*02 (OK!)

        if (sentence_type != SENTENCE_UNK &&      // Known sentence?

            strcmp(gga_time, rmc_time) == 0 &&    // RMC/GGA times match?

            active) {                             // Valid fix?

          // Atomically merge data from the two sentences

          strcpy(gps_time, new_time);

          gps_seconds = new_seconds;

          gps_lat = new_lat;

          gps_lon = new_lon;

          strcpy(gps_aprs_lat, new_aprs_lat);

          strcpy(gps_aprs_lon, new_aprs_lon);

          gps_course = new_course;

          gps_speed = new_speed;

          gps_altitude = new_altitude;

          ret = true;

        }

      }

#ifdef DEBUG_GPS

      if (num_tokens)

        Serial.println();

#endif

      at_checksum = false;        // CR/LF signals the end of the checksum

      our_checksum = '$';         // Reset checksums

      their_checksum = 0;

      offset = 0;                 // Prepare for the next incoming sentence

      num_tokens = 0;

      sentence_type = SENTENCE_UNK;

      break;

    case '*':

      // Handle as ',', but prepares to receive checksum (ie. do not break)

      at_checksum = true;

      our_checksum ^= c;

    case ',':

      // Process token

      token[offset] = '\0';

      our_checksum ^= c;  // Checksum the ',', undo the '*'

      // Parse token

      switch (sentence_type) {

        case SENTENCE_UNK:

          if (num_tokens < NUM_OF_UNK_PARSERS && unk_parsers[num_tokens])

            unk_parsers[num_tokens](token);

          break;

        case SENTENCE_GGA:

          if (num_tokens < NUM_OF_GGA_PARSERS && gga_parsers[num_tokens])

            gga_parsers[num_tokens](token);

          break;

        case SENTENCE_RMC:

          if (num_tokens < NUM_OF_RMC_PARSERS && rmc_parsers[num_tokens])

            rmc_parsers[num_tokens](token);

          break;

      }

      // Prepare for next token

      num_tokens++;

      offset = 0;

#ifdef DEBUG_GPS

      Serial.print(c);

#endif

      break;

    default:

      // Any other character

      if (at_checksum) {

        // Checksum value

        their_checksum = their_checksum * 16 + from_hex(c);

      } else {

        // Regular NMEA data

        if (offset < 15) {  // Avoid buffer overrun (tokens can't be > 15 chars)

          token[offset] = c;

          offset++;

          our_checksum ^= c;

        }

      }

#ifdef DEBUG_GPS

      Serial.print(c);

#endif

  }

  return ret;

}

/* trackuino copyright (C) 2010  EA5HAV Javi

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

 */

#include "config.h"

#include "gps.h"

#include <WProgram.h>

#include <stdlib.h>

#include <string.h>

// Module declarations

static void parse_sentence_type(const char * token);

static void parse_time(const char *token);

static void parse_status(const char *token);

static void parse_lat(const char *token);

static void parse_lat_hemi(const char *token);

static void parse_lon(const char *token);

static void parse_lon_hemi(const char *token);

static void parse_speed(const char *token);

static void parse_course(const char *token);

static void parse_altitude(const char *token);

// Module types

typedef void (*t_nmea_parser)(const char *token);

enum t_sentence_type {

  SENTENCE_UNK,

  SENTENCE_GGA,

  SENTENCE_RMC

};

// Module constants

static const t_nmea_parser unk_parsers[] = {

  parse_sentence_type,    // $GPxxx

};

static const t_nmea_parser gga_parsers[] = {

  NULL,             // $GPGGA

  parse_time,       // Time

  NULL,             // Latitude

  NULL,             // N/S

  NULL,             // Longitude

  NULL,             // E/W

  NULL,             // Fix quality 

  NULL,             // Number of satellites

  NULL,             // Horizontal dilution of position

  parse_altitude,   // Altitude

  NULL,             // "M" (mean sea level)

  NULL,             // Height of GEOID (MSL) above WGS84 ellipsoid

  NULL,             // "M" (mean sea level)

  NULL,             // Time in seconds since the last DGPS update

  NULL              // DGPS station ID number

};

static const t_nmea_parser rmc_parsers[] = {

  NULL,             // $GPRMC

  parse_time,       // Time

  parse_status,     // A=active, V=void

  parse_lat,        // Latitude,

  parse_lat_hemi,   // N/S

  parse_lon,        // Longitude

  parse_lon_hemi,   // E/W

  parse_speed,      // Speed over ground in knots

  parse_course,     // Track angle in degrees (true)

  NULL,             // Date (DDMMYY)

  NULL,             // Magnetic variation

  NULL              // E/W

};

static const int NUM_OF_UNK_PARSERS = (sizeof(unk_parsers) / sizeof(t_nmea_parser));

static const int NUM_OF_GGA_PARSERS = (sizeof(gga_parsers) / sizeof(t_nmea_parser));

static const int NUM_OF_RMC_PARSERS = (sizeof(rmc_parsers) / sizeof(t_nmea_parser));

// Module variables

static t_sentence_type sentence_type = SENTENCE_UNK;

static bool at_checksum = false;

static unsigned char our_checksum = '$';

static unsigned char their_checksum = 0;

static char token[16];

static int num_tokens = 0;

static unsigned int offset = 0;

static bool active = false;

static char gga_time[7] = "", rmc_time[7] = "";

static char new_time[7];

static uint32_t new_seconds;

static float new_lat;

static float new_lon;

static char new_aprs_lat[9];

static char new_aprs_lon[10];

static float new_course;

static float new_speed;

static float new_altitude;

// Public (extern) variables, readable from other modules

char gps_time[7];       // HHMMSS

uint32_t gps_seconds = 0;   // seconds after midnight

float gps_lat = 0;

float gps_lon = 0;

char gps_aprs_lat[9];

char gps_aprs_lon[10];

float gps_course = 0;

float gps_speed = 0;

float gps_altitude = 0;

// Module functions

unsigned char from_hex(char a) 

{

  if (a >= 'A' && a <= 'F')

    return a - 'A' + 10;

  else if (a >= 'a' && a <= 'f')

    return a - 'a' + 10;

  else if (a >= '0' && a <= '9')

    return a - '0';

  else

    return 0;

}

void parse_sentence_type(const char *token)

{

  if (strcmp(token, "$GPGGA") == 0) {

    sentence_type = SENTENCE_GGA;

  } else if (strcmp(token, "$GPRMC") == 0) {

    sentence_type = SENTENCE_RMC;

  } else {

    sentence_type = SENTENCE_UNK;

  }

}

void parse_time(const char *token)

{

  // Time can have decimals (fractions of a second), but we only take HHMMSS

  strncpy(new_time, token, 6);

  // Terminate string

  new_time[6] = '\0';

  new_seconds = 

    ((new_time[0] - '0') * 10 + (new_time[1] - '0')) * 60 * 60UL +

    ((new_time[2] - '0') * 10 + (new_time[3] - '0')) * 60 +

    ((new_time[4] - '0') * 10 + (new_time[5] - '0'));

}

void parse_status(const char *token)

{

  // "A" = active, "V" = void. We shoud disregard void sentences

  if (strcmp(token, "A") == 0)

    active = true;

  else

    active = false;

}

void parse_lat(const char *token)

{

  // Parses latitude in the format "DD" + "MM" (+ ".M{...}M")

  char degs[3];

  if (strlen(token) >= 4) {

    degs[0] = token[0];

    degs[1] = token[1];

    degs[2] = '\0';

    new_lat = atof(degs) + atof(token + 2) / 60;

  }

  // APRS-ready latitude

  strncpy(new_aprs_lat, token, 7);

  new_aprs_lat[7] = '\0';

}

void parse_lat_hemi(const char *token)

{

  if (token[0] == 'S')

    new_lat = -new_lat;

  new_aprs_lat[7] = token[0];

  new_aprs_lon[8] = '\0';

}

void parse_lon(const char *token)

{

  // Longitude is in the format "DDD" + "MM" (+ ".M{...}M")

  char degs[4];

  if (strlen(token) >= 5) {

    degs[0] = token[0];

    degs[1] = token[1];

    degs[2] = token[2];

    degs[3] = '\0';

    new_lon = atof(degs) + atof(token + 3) / 60;

  }

  // APRS-ready longitude

  strncpy(new_aprs_lon, token, 8);

  new_aprs_lon[8] = '\0';

}

void parse_lon_hemi(const char *token)

{

  if (token[0] == 'W')

    new_lon = -new_lon;

  new_aprs_lon[8] = token[0];

  new_aprs_lon[9] = '\0';

}

void parse_speed(const char *token)

{

  new_speed = atof(token);

}

void parse_course(const char *token)

{

  new_course = atof(token);

}

void parse_altitude(const char *token)

{

  new_altitude = atof(token);

}

//

// Exported functions

//

void gps_setup() {

  strcpy(gps_time, "000000");

  strcpy(gps_aprs_lat, "0000.00N");

  strcpy(gps_aprs_lon, "00000.00E");

}

bool gps_decode(char c)

{

  int ret = false;

  switch(c) {

    case '\r':

    case '\n':

      // End of sentence

      if (num_tokens && our_checksum == their_checksum) {

#ifdef DEBUG_GPS

        Serial.print(" (OK!) ");

        Serial.print(millis());

#endif

        // Return a valid position only when we've got two rmc and gga

        // messages with the same timestamp.

        switch (sentence_type) {

          case SENTENCE_UNK:

            break;    // Keeps gcc happy

          case SENTENCE_GGA:

            strcpy(gga_time, new_time);

            break;

          case SENTENCE_RMC:

            strcpy(rmc_time, new_time);

            break;

        }

        // Valid position scenario:

        //

        // 1. The timestamps of the two previous GGA/RMC sentences must match.

        //

        // 2. We just processed a known (GGA/RMC) sentence. Suppose the

        //    contrary: after starting up this module, gga_time and rmc_time

        //    are both equal (they're both initialized to ""), so (1) holds

        //    and we wrongly report a valid position.

        //

        // 3. The GPS has a valid fix. For some reason, the Venus 634FLPX

        //    reports 24 deg N, 121 deg E (the middle of Taiwan) until a valid

        //    fix is acquired:

        //

        //    $GPGGA,120003.000,2400.0000,N,12100.0000,E,0,00,0.0,0.0,M,0.0,M,,0000*69 (OK!)

        //    $GPGSA,A,1,,,,,,,,,,,,,0.0,0.0,0.0*30 (OK!)

        //    $GPRMC,120003.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*78 (OK!)

        //    $GPVTG,000.0,T,,M,000.0,N,000.0,K,N*02 (OK!)

        if (sentence_type != SENTENCE_UNK &&      // Known sentence?

            strcmp(gga_time, rmc_time) == 0 &&    // RMC/GGA times match?

            active) {                             // Valid fix?

          // Atomically merge data from the two sentences

          strcpy(gps_time, new_time);

          gps_seconds = new_seconds;

          gps_lat = new_lat;

          gps_lon = new_lon;