2021 mbed Grove GPS
GroveGPS.h
- Committer:
- c1728p9
- Date:
- 2019-06-06
- Revision:
- 3:037ec2b52d31
- Parent:
- 2:82fce70de15f
- Child:
- 4:0ee729b4a211
File content as of revision 3:037ec2b52d31:
#ifndef _GROVE_GPS_H_ #define _GROVE_GPS_H_ #include "mbed.h" #include <stdlib.h> #include <string> class GroveGPS { public: GroveGPS(PinName tx=D1, PinName rx=D0) : _last_line(""), gps_serial(tx, rx, 9600) {} void readCharacter(char newCharacter) { if (newCharacter == '\n') { parseLine(); _last_line = ""; } else { _last_line += newCharacter; } if (_last_line.length() > max_line_length) { error("GPS error - line too long"); _last_line = ""; } } struct GGA { double utc_time; // Format: hhmmss.sss double latitude; // Format: ddmm.mmmm char ns_indicator; // Format: N=north or S=south double longitude; // Format: dddmm.mmmm char ew_indicator; // Format: E=east or W=west int position_fix; // Options: [0=not available, 1=GPS SPS mode, 2=Differential GPS, 6=dead reckoning] int sats_used; // Range: 0-12 double hdop; // Horizontal Dilution of Precision double msl_altitude; char msl_altitude_units; double geoid_separation; char geoid_separation_units; long age_of_diff; long diff_ref_station_id; std::string checksum; } gps_gga; void getTimestamp(char* buffer) { m.lock(); sprintf(buffer, "%f", gps_gga.utc_time); m.unlock(); } void getLatitude(char* buffer) { m.lock(); double coordinate = convertGPSToDecimal(gps_gga.latitude); if (gps_gga.position_fix==0) sprintf(buffer, "N/A"); else sprintf(buffer, "%c%f", (gps_gga.ns_indicator == 'N') ? '0' : '-', coordinate); m.unlock(); } void getLongitude(char* buffer) { m.lock(); double coordinate = convertGPSToDecimal(gps_gga.longitude); if (gps_gga.position_fix==0) sprintf(buffer, "N/A"); else sprintf(buffer, "%c%f", (gps_gga.ew_indicator == 'E') ? '0' : '-', coordinate); m.unlock(); } void start() { serial_thread.start(callback(this, &GroveGPS::read_serial)); } private: static const size_t max_line_length = 1024; std::string _last_line; Thread serial_thread; Serial gps_serial; Mutex m; void read_serial() { while (true) { if (gps_serial.readable()) { readCharacter(gps_serial.getc()); } } } double convertGPSToDecimal(double coordinate) { int degrees = coordinate/100.0; int minutes = ((int)coordinate) % 100; double seconds = coordinate - ((int)coordinate); return degrees + (minutes+seconds)/60; } void parseLine() { if (_last_line.find("GPGGA") != std::string::npos) { m.lock(); parseGGA(); m.unlock(); } } void parseGGA() { char* pEnd; for (int i=0; i<14; i++) { std::string current_item = _last_line.substr(0,_last_line.find(",")); _last_line = _last_line.substr(_last_line.find(",")+1); if (i==0) { // NMEA Tag } else if (i==1) { // UTC time gps_gga.utc_time = strtod(current_item.c_str(), &pEnd); } else if (i==2) { // Latitude gps_gga.latitude = strtod(current_item.c_str(), &pEnd); } else if (i==3) { // Latitude North/South indicator gps_gga.ns_indicator = current_item[0]; } else if (i==4) { // Longitude gps_gga.longitude = strtod(current_item.c_str(), &pEnd); } else if (i==5) { // Longitude indicator gps_gga.ew_indicator = current_item[0]; } else if (i==6) { gps_gga.position_fix = strtod(current_item.c_str(), &pEnd); } } } }; #endif