Diff: GroveGPS.h

Revision:

0:56d6407653a7

Child:

1:0607ba3aa02d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GroveGPS.h	Tue Jan 30 13:04:53 2018 -0600
@@ -0,0 +1,101 @@
+#ifndef _GROVE_GPS_H_
+#define _GROVE_GPS_H_
+
+#include "mbed.h"
+#include <stdlib.h>
+#include <string>
+
+class GroveGPS {
+
+public:
+
+	GroveGPS() : _last_line("") {}
+
+	void readCharacter(char newCharacter) {
+		if (newCharacter == '\n') {
+			parseLine();
+			_last_line = "";
+		} else {
+			_last_line += newCharacter;
+		}
+	}
+
+	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) {
+		sprintf(buffer, "%f", gps_gga.utc_time);
+	}
+
+	void getLatitude(char* buffer) {
+		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);
+	}
+
+	void getLongitude(char* buffer) {
+		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);
+	}
+
+private:
+	std::string _last_line;
+
+	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) {
+			parseGGA();
+		}
+	}
+
+	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
\ No newline at end of file