Support added for NMEA Data Protocol v3.x and GLONASS

Readme.md

@@ -0,0 +1,73 @@
+# TinyGPS refresh for NMEA Data Protocol v3.x and GLONASS
+
+This update adds support for newer NMEA-capable GPS devices that implement the [v3.x GNSS spec](http://geostar-navigation.com/file/geos3/geos_nmea_protocol_v3_0_eng.pdf) as well as devices that support [GLONASS](https://en.wikipedia.org/wiki/GLONASS).
+
+#### The following new sentences are now supported:
+
+1. NMEA GPS sentence:
+* GPS Satellites in view [GPGSV](http://aprs.gids.nl/nmea/#gsv)
+2. GNSS sentences:
+* GNRMC (same with GPRMC)
+* GNGNS
+3. GLONASS sentences:
+* GLGSV
+
+#### Tracking satellites in view for both GPS and GLONASS constellations.
+
+This allows for building e.g. an advanced GUI that shows the satellites in view and their respective strength both when searching and when tracking.
+The data is accessible via a new method: `uint32_t[] trackedSattelites()` that returns an array of uint32 that (to keep the additional memory footprint at a minimum) encodes the useful data as follows (check [GPGSV](http://aprs.gids.nl/nmea/#gsv) for a comprehensive explanation ):
+
+  * bit 0-7: sattelite ID
+  * bit 8-14: SNR (dB), max 99dB
+  * bit 15: this sattelite is used in solution (not implemented yet)
+
+The uint32 array size is 24, that is, it tracks up to 12 satellites for each constellation, GPS and GLONASS. 12 is the maximum number of satellites in view per constellation at any given point on Earth.
+```c
+...
+  char buf[32];
+  uint32_t* satz = tinygps.trackedSatellites();
+  uint8_t sat_count = 0;
+  for(int i=0;i<24;i++)
+  {
+    if(satz[i] != 0)	//exclude zero SNR sats
+    {
+      sat_count++;
+      sprintf(buf, "PRN %d: %ddB ", satz[i]>>8, (satz[i]&0xFF)>>1);
+      Serial.println(buf);
+    }
+  }
+
+```
+
+This code produces an output of this form: ```PRN 21: 31dB PRN 11: 25dB PRN 71: 24dB ...``` where satellite ID and the strength are displayed for each satellite in view.
+Additional notes from NMEA protocol v3.0:
+
+> GPS satellites are identified by their PRN numbers, which range from 1 to 32.
+
+> The numbers 65-96 are reserved for GLONASS satellites. GLONASS satellites are identified by 64+satellite slot number. The slot numbers are 1 through 24 for the full constellation of 24 satellites, this gives a range of 65 through 88. The numbers 89 through 96 are available if slot numbers above 24 are allocated to on-orbit spares.
+
+The array is grouped by constellations with GPS first.
+
+#### GNS mode indicator
+
+Fix data now includes a field that shows which constellations are used when tracking, Accessible via a new ```char[] constellations()``` method that returns a char array on the following spec:
+> Mode Indicator:
+A variable length valid character field type with the first two characters currently defined. The first character indicates the use of GPS satellites, the second character indicates the use of GLONASS satellites. If another satellite system is added to the standard, the mode indicator will be extended to three characters, new satellite systems shall always be added on the right, so the order of characters in the Mode Indicator is: GPS, GLONASS, other satellite systems in the future.
+The characters shall take one of the following values:
+
+* N = No fix
+* A = Autonomous mode
+* D = Differential mode
+* P = Precise mode is used to compute position fix
+* R = Real Time Kinematic
+* F = Float RTK
+* E = Estimated (dead reckoning) mode
+* M = Manual input mode
+* S = Simulator mode.
+
+For example, a return of ```AA``` when calling ```constellations()``` means that both GPS and GLONASS are used when the device is tracking, ```AN``` means only GPS is used, etc.
+
+#### Time and date available when the GPS is not tracking
+
+Now the time and date are also updated even when the device is not tracking since a valid date and time is computed when enough satellites are in view. Use with caution as it may yield false date and time.
+

TinyGPS.cpp

@@ -25,6 +25,12 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 #define _GPRMC_TERM   "GPRMC"
 #define _GPGGA_TERM   "GPGGA"
+#define _GPGSA_TERM   "GPGSA"
+#define _GNRMC_TERM   "GNRMC"
+#define _GNGNS_TERM   "GNGNS"
+#define _GNGSA_TERM   "GNGSA"
+#define _GPGSV_TERM   "GPGSV"
+#define _GLGSV_TERM   "GLGSV"
 
 TinyGPS::TinyGPS()
   :  _time(GPS_INVALID_TIME)
@@ -170,6 +176,11 @@ bool TinyGPS::term_complete()
     byte checksum = 16 * from_hex(_term[0]) + from_hex(_term[1]);
     if (checksum == _parity)
     {
+      if(_sentence_type == _GPS_SENTENCE_GPRMC)   //set the time and date even if not tracking
+      {
+          _time      = _new_time;
+          _date      = _new_date;
+      }
       if (_gps_data_good)
       {
 #ifndef _GPS_NO_STATS
@@ -212,10 +223,18 @@ bool TinyGPS::term_complete()
   // the first term determines the sentence type
   if (_term_number == 0)
   {
-    if (!gpsstrcmp(_term, _GPRMC_TERM))
+    if (!gpsstrcmp(_term, _GPRMC_TERM) || !gpsstrcmp(_term, _GNRMC_TERM))
       _sentence_type = _GPS_SENTENCE_GPRMC;
     else if (!gpsstrcmp(_term, _GPGGA_TERM))
       _sentence_type = _GPS_SENTENCE_GPGGA;
+    else if (!gpsstrcmp(_term, _GNGNS_TERM))
+      _sentence_type = _GPS_SENTENCE_GNGNS;
+    else if (!gpsstrcmp(_term, _GNGSA_TERM) || !gpsstrcmp(_term, _GPGSA_TERM))
+      _sentence_type = _GPS_SENTENCE_GNGSA;
+    else if (!gpsstrcmp(_term, _GPGSV_TERM))
+      _sentence_type = _GPS_SENTENCE_GPGSV;
+    else if (!gpsstrcmp(_term, _GLGSV_TERM))
+      _sentence_type = _GPS_SENTENCE_GLGSV;
     else
       _sentence_type = _GPS_SENTENCE_OTHER;
     return false;
@@ -226,6 +245,7 @@ bool TinyGPS::term_complete()
   {
     case COMBINE(_GPS_SENTENCE_GPRMC, 1): // Time in both sentences
     case COMBINE(_GPS_SENTENCE_GPGGA, 1):
+    case COMBINE(_GPS_SENTENCE_GNGNS, 1):
       _new_time = parse_decimal();
       _new_time_fix = millis();
       break;
@@ -234,23 +254,30 @@ bool TinyGPS::term_complete()
       break;
     case COMBINE(_GPS_SENTENCE_GPRMC, 3): // Latitude
     case COMBINE(_GPS_SENTENCE_GPGGA, 2):
+    case COMBINE(_GPS_SENTENCE_GNGNS, 2):
       _new_latitude = parse_degrees();
       _new_position_fix = millis();
       break;
     case COMBINE(_GPS_SENTENCE_GPRMC, 4): // N/S
     case COMBINE(_GPS_SENTENCE_GPGGA, 3):
+    case COMBINE(_GPS_SENTENCE_GNGNS, 3):
       if (_term[0] == 'S')
         _new_latitude = -_new_latitude;
       break;
     case COMBINE(_GPS_SENTENCE_GPRMC, 5): // Longitude
     case COMBINE(_GPS_SENTENCE_GPGGA, 4):
+    case COMBINE(_GPS_SENTENCE_GNGNS, 4):
       _new_longitude = parse_degrees();
       break;
     case COMBINE(_GPS_SENTENCE_GPRMC, 6): // E/W
     case COMBINE(_GPS_SENTENCE_GPGGA, 5):
+    case COMBINE(_GPS_SENTENCE_GNGNS, 5):
       if (_term[0] == 'W')
         _new_longitude = -_new_longitude;
       break;
+    case COMBINE(_GPS_SENTENCE_GNGNS, 6):
+      strncpy(_constellations, _term, 5);
+      break;
     case COMBINE(_GPS_SENTENCE_GPRMC, 7): // Speed (GPRMC)
       _new_speed = parse_decimal();
       break;
@@ -263,7 +290,8 @@ bool TinyGPS::term_complete()
     case COMBINE(_GPS_SENTENCE_GPGGA, 6): // Fix data (GPGGA)
       _gps_data_good = _term[0] > '0';
       break;
-    case COMBINE(_GPS_SENTENCE_GPGGA, 7): // Satellites used (GPGGA)
+    case COMBINE(_GPS_SENTENCE_GPGGA, 7): // Satellites used (GPGGA): GPS only
+    case COMBINE(_GPS_SENTENCE_GNGNS, 7): //  GNGNS counts-in all constellations
       _new_numsats = (unsigned char)atoi(_term);
       break;
     case COMBINE(_GPS_SENTENCE_GPGGA, 8): // HDOP
@@ -272,6 +300,64 @@ bool TinyGPS::term_complete()
     case COMBINE(_GPS_SENTENCE_GPGGA, 9): // Altitude (GPGGA)
       _new_altitude = parse_decimal();
       break;
+    case COMBINE(_GPS_SENTENCE_GNGSA, 3): //satellites used in solution: 3 to 15
+      //_sats_used[
+      break;
+    case COMBINE(_GPS_SENTENCE_GPGSV, 2):   //beginning of sequence
+    case COMBINE(_GPS_SENTENCE_GLGSV, 2):   //beginning of sequence
+    {
+      uint8_t msgId = atoi(_term)-1;  //start from 0
+      if(msgId == 0) {
+        //http://geostar-navigation.com/file/geos3/geos_nmea_protocol_v3_0_eng.pdf
+        if(_sentence_type == _GPS_SENTENCE_GPGSV) {
+          //reset GPS & WAAS trackedSatellites
+          for(uint8_t x=0;x<12;x++)
+          {
+            tracked_sat_rec[x] = 0;
+          }
+        } else {
+          //reset GLONASS trackedSatellites: range starts with 23
+          for(uint8_t x=12;x<24;x++)
+          {
+            tracked_sat_rec[x] = 0;
+          }
+        }
+      }
+      _sat_index = msgId*4;   //4 sattelites/line
+      if(_sentence_type == _GPS_SENTENCE_GLGSV)
+      {
+        _sat_index = msgId*4 + 12;   //Glonass offset by 12
+      }
+      break;
+  }
+    case COMBINE(_GPS_SENTENCE_GPGSV, 4):   //satellite #
+    case COMBINE(_GPS_SENTENCE_GPGSV, 8):
+    case COMBINE(_GPS_SENTENCE_GPGSV, 12):
+    case COMBINE(_GPS_SENTENCE_GPGSV, 16):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 4):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 8):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 12):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 16):
+      _tracked_satellites_index = atoi(_term);
+      break;
+    case COMBINE(_GPS_SENTENCE_GPGSV, 7):   //strength
+    case COMBINE(_GPS_SENTENCE_GPGSV, 11):
+    case COMBINE(_GPS_SENTENCE_GPGSV, 15):
+    case COMBINE(_GPS_SENTENCE_GPGSV, 19):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 7):   //strength
+    case COMBINE(_GPS_SENTENCE_GLGSV, 11):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 15):
+    case COMBINE(_GPS_SENTENCE_GLGSV, 19):
+      uint8_t stren = (uint8_t)atoi(_term);
+      if(stren == 0)  //remove the record, 0dB strength
+      {
+        tracked_sat_rec[_sat_index + (_term_number-7)/4] = 0;
+      }
+      else
+      {
+        tracked_sat_rec[_sat_index + (_term_number-7)/4] = _tracked_satellites_index<<8 | stren<<1;
+      }
+      break;
   }
 
   return false;

TinyGPS.h

@@ -79,6 +79,9 @@ class TinyGPS
   // horizontal dilution of precision in 100ths
   inline unsigned long hdop() { return _hdop; }
 
+  inline char* constellations() { return _constellations; }
+  inline uint32_t* trackedSatellites() { return tracked_sat_rec; }
+
   void f_get_position(float *latitude, float *longitude, unsigned long *fix_age = 0);
   void crack_datetime(int *year, byte *month, byte *day, 
     byte *hour, byte *minute, byte *second, byte *hundredths = 0, unsigned long *fix_age = 0);
@@ -100,7 +103,8 @@ class TinyGPS
 #endif
 
 private:
-  enum {_GPS_SENTENCE_GPGGA, _GPS_SENTENCE_GPRMC, _GPS_SENTENCE_OTHER};
+  enum {_GPS_SENTENCE_GPGGA, _GPS_SENTENCE_GPRMC, _GPS_SENTENCE_GNGNS, _GPS_SENTENCE_GNGSA,
+      _GPS_SENTENCE_GPGSV, _GPS_SENTENCE_GLGSV,  _GPS_SENTENCE_OTHER};
 
   // properties
   unsigned long _time, _new_time;
@@ -124,6 +128,22 @@ class TinyGPS
   byte _term_number;
   byte _term_offset;
   bool _gps_data_good;
+
+  struct TrackedSattelites {
+      uint8_t prn;      //"pseudo-random noise" sequences, or Gold codes. GPS sats are listed here http://en.wikipedia.org/wiki/List_of_GPS_satellites
+      uint8_t strength; //in dB
+  };
+
+  char _constellations[5];
+  uint8_t _sat_used_count;
+
+  //format:
+  //bit 0-7: sat ID
+  //bit 8-14: snr (dB), max 99dB
+  //bit 15: used in solution (when tracking)
+  uint32_t tracked_sat_rec[24]; //TODO: externalize array size
+  int _tracked_satellites_index;
+  uint8_t _sat_index;
 
 #ifndef _GPS_NO_STATS
   // statistics