Sarah Marsh / GroveGPS

GroveGPS Library

Dependents:   GroveGPS-Example

GroveGPS.h@1:0607ba3aa02d, 2019-05-23 (annotated)

Committer:
sarahmarshy
Date:
Thu May 23 16:10:05 2019 +0000
Revision:
1:0607ba3aa02d
Parent:
0:56d6407653a7
Child:
2:82fce70de15f
Use internal thread to read serial bus

Who changed what in which revision?

UserRevisionLine numberNew contents of line
michaelray 0:56d6407653a7 1 #ifndef _GROVE_GPS_H_
michaelray 0:56d6407653a7 2 #define _GROVE_GPS_H_
michaelray 0:56d6407653a7 3
michaelray 0:56d6407653a7 4 #include "mbed.h"
michaelray 0:56d6407653a7 5 #include <stdlib.h>
michaelray 0:56d6407653a7 6 #include <string>
michaelray 0:56d6407653a7 7
michaelray 0:56d6407653a7 8 class GroveGPS {
michaelray 0:56d6407653a7 9
michaelray 0:56d6407653a7 10 public:
michaelray 0:56d6407653a7 11
sarahmarshy 1:0607ba3aa02d 12 GroveGPS(PinName tx=D1, PinName rx=D0) : _last_line(""), gps_serial(tx, rx) {}
michaelray 0:56d6407653a7 13
michaelray 0:56d6407653a7 14 void readCharacter(char newCharacter) {
michaelray 0:56d6407653a7 15 if (newCharacter == '\n') {
michaelray 0:56d6407653a7 16 parseLine();
michaelray 0:56d6407653a7 17 _last_line = "";
michaelray 0:56d6407653a7 18 } else {
michaelray 0:56d6407653a7 19 _last_line += newCharacter;
michaelray 0:56d6407653a7 20 }
michaelray 0:56d6407653a7 21 }
michaelray 0:56d6407653a7 22
michaelray 0:56d6407653a7 23 struct GGA {
michaelray 0:56d6407653a7 24 double utc_time; // Format: hhmmss.sss
michaelray 0:56d6407653a7 25 double latitude; // Format: ddmm.mmmm
michaelray 0:56d6407653a7 26 char ns_indicator; // Format: N=north or S=south
michaelray 0:56d6407653a7 27 double longitude; // Format: dddmm.mmmm
michaelray 0:56d6407653a7 28 char ew_indicator; // Format: E=east or W=west
michaelray 0:56d6407653a7 29 int position_fix; // Options: [0=not available, 1=GPS SPS mode, 2=Differential GPS, 6=dead reckoning]
michaelray 0:56d6407653a7 30 int sats_used; // Range: 0-12
michaelray 0:56d6407653a7 31 double hdop; // Horizontal Dilution of Precision
michaelray 0:56d6407653a7 32 double msl_altitude;
michaelray 0:56d6407653a7 33 char msl_altitude_units;
michaelray 0:56d6407653a7 34 double geoid_separation;
michaelray 0:56d6407653a7 35 char geoid_separation_units;
michaelray 0:56d6407653a7 36 long age_of_diff;
michaelray 0:56d6407653a7 37 long diff_ref_station_id;
michaelray 0:56d6407653a7 38 std::string checksum;
michaelray 0:56d6407653a7 39 } gps_gga;
michaelray 0:56d6407653a7 40
michaelray 0:56d6407653a7 41 void getTimestamp(char* buffer) {
sarahmarshy 1:0607ba3aa02d 42 m.lock();
michaelray 0:56d6407653a7 43 sprintf(buffer, "%f", gps_gga.utc_time);
sarahmarshy 1:0607ba3aa02d 44 m.unlock();
michaelray 0:56d6407653a7 45 }
michaelray 0:56d6407653a7 46
michaelray 0:56d6407653a7 47 void getLatitude(char* buffer) {
sarahmarshy 1:0607ba3aa02d 48 m.lock();
michaelray 0:56d6407653a7 49 double coordinate = convertGPSToDecimal(gps_gga.latitude);
michaelray 0:56d6407653a7 50 if (gps_gga.position_fix==0)
michaelray 0:56d6407653a7 51 sprintf(buffer, "N/A");
michaelray 0:56d6407653a7 52 else
michaelray 0:56d6407653a7 53 sprintf(buffer, "%c%f", (gps_gga.ns_indicator == 'N') ? '0' : '-', coordinate);
sarahmarshy 1:0607ba3aa02d 54 m.unlock();
michaelray 0:56d6407653a7 55 }
michaelray 0:56d6407653a7 56
michaelray 0:56d6407653a7 57 void getLongitude(char* buffer) {
sarahmarshy 1:0607ba3aa02d 58 m.lock();
michaelray 0:56d6407653a7 59 double coordinate = convertGPSToDecimal(gps_gga.longitude);
michaelray 0:56d6407653a7 60 if (gps_gga.position_fix==0)
michaelray 0:56d6407653a7 61 sprintf(buffer, "N/A");
michaelray 0:56d6407653a7 62 else
michaelray 0:56d6407653a7 63 sprintf(buffer, "%c%f", (gps_gga.ew_indicator == 'E') ? '0' : '-', coordinate);
sarahmarshy 1:0607ba3aa02d 64 m.unlock();
michaelray 0:56d6407653a7 65 }
sarahmarshy 1:0607ba3aa02d 66
sarahmarshy 1:0607ba3aa02d 67 void start() {
sarahmarshy 1:0607ba3aa02d 68 serial_thread.start(callback(this, &GroveGPS::read_serial));
sarahmarshy 1:0607ba3aa02d 69 }
sarahmarshy 1:0607ba3aa02d 70
michaelray 0:56d6407653a7 71
michaelray 0:56d6407653a7 72 private:
michaelray 0:56d6407653a7 73 std::string _last_line;
sarahmarshy 1:0607ba3aa02d 74 Thread serial_thread;
sarahmarshy 1:0607ba3aa02d 75 Serial gps_serial;
sarahmarshy 1:0607ba3aa02d 76 Mutex m;
sarahmarshy 1:0607ba3aa02d 77 void read_serial() {
sarahmarshy 1:0607ba3aa02d 78 while (true) {
sarahmarshy 1:0607ba3aa02d 79 if (gps_serial.readable()) {
sarahmarshy 1:0607ba3aa02d 80 readCharacter(gps_serial.getc());
sarahmarshy 1:0607ba3aa02d 81 }
sarahmarshy 1:0607ba3aa02d 82 }
sarahmarshy 1:0607ba3aa02d 83 }
michaelray 0:56d6407653a7 84
michaelray 0:56d6407653a7 85 double convertGPSToDecimal(double coordinate) {
michaelray 0:56d6407653a7 86 int degrees = coordinate/100.0;
michaelray 0:56d6407653a7 87 int minutes = ((int)coordinate) % 100;
michaelray 0:56d6407653a7 88 double seconds = coordinate - ((int)coordinate);
michaelray 0:56d6407653a7 89 return degrees + (minutes+seconds)/60;
michaelray 0:56d6407653a7 90
michaelray 0:56d6407653a7 91 }
michaelray 0:56d6407653a7 92
michaelray 0:56d6407653a7 93 void parseLine() {
michaelray 0:56d6407653a7 94 if (_last_line.find("GPGGA") != std::string::npos) {
sarahmarshy 1:0607ba3aa02d 95 m.lock();
michaelray 0:56d6407653a7 96 parseGGA();
sarahmarshy 1:0607ba3aa02d 97 m.unlock();
michaelray 0:56d6407653a7 98 }
michaelray 0:56d6407653a7 99 }
michaelray 0:56d6407653a7 100
michaelray 0:56d6407653a7 101 void parseGGA() {
michaelray 0:56d6407653a7 102 char* pEnd;
michaelray 0:56d6407653a7 103 for (int i=0; i<14; i++) {
michaelray 0:56d6407653a7 104 std::string current_item = _last_line.substr(0,_last_line.find(","));
michaelray 0:56d6407653a7 105 _last_line = _last_line.substr(_last_line.find(",")+1);
michaelray 0:56d6407653a7 106 if (i==0) { // NMEA Tag
michaelray 0:56d6407653a7 107 } else if (i==1) { // UTC time
michaelray 0:56d6407653a7 108 gps_gga.utc_time = strtod(current_item.c_str(), &pEnd);
michaelray 0:56d6407653a7 109 } else if (i==2) { // Latitude
michaelray 0:56d6407653a7 110 gps_gga.latitude = strtod(current_item.c_str(), &pEnd);
michaelray 0:56d6407653a7 111 } else if (i==3) { // Latitude North/South indicator
michaelray 0:56d6407653a7 112 gps_gga.ns_indicator = current_item[0];
michaelray 0:56d6407653a7 113 } else if (i==4) { // Longitude
michaelray 0:56d6407653a7 114 gps_gga.longitude = strtod(current_item.c_str(), &pEnd);
michaelray 0:56d6407653a7 115 } else if (i==5) { // Longitude indicator
michaelray 0:56d6407653a7 116 gps_gga.ew_indicator = current_item[0];
michaelray 0:56d6407653a7 117 } else if (i==6) {
michaelray 0:56d6407653a7 118 gps_gga.position_fix = strtod(current_item.c_str(), &pEnd);
michaelray 0:56d6407653a7 119 }
michaelray 0:56d6407653a7 120 }
michaelray 0:56d6407653a7 121 }
michaelray 0:56d6407653a7 122 };
michaelray 0:56d6407653a7 123
sarahmarshy 1:0607ba3aa02d 124 #endif