Joseph Bradshaw / GPSINT

library for parsing GPS NMEA strings using serial receive interrupt

Fork of GPSINT by Joseph Bradshaw

GPSINT library

Library class for intercepting NMEA-0183 ASCII strings from a GPS using a serial interrupt at 4800 baud, error checking, and parsing using the scanf functions to update object associated variables

include the mbed library with this snippet

// mbed GPS Parse Program, tested using the Trimble Copernicus II
#include "mbed.h"
#include "GPSINT.h"

#define TIMEZONE -4 //Eastern Standard Time

Serial pc(USBTX,USBRX);
GPSINT gps(p28, p27);   //Tx,Rx
DigitalOut led1(LED1);

// ---------------- MAIN ------------------------
int main() {        
    pc.baud(921600);
  
    while(1) {
        if(gps.lock != 0){
            led1=!led1;
            
            int gpsHour = (int)((int)gps.utc_time/10000) + TIMEZONE;
            if(gpsHour < 0)
                gpsHour += 24;
            
            int gpsMin = (int)((int)gps.utc_time/100%100);
            int gpsSec = (int)gps.utc_time % 100;
      
            pc.printf("lock=%d %2d:%02d:%02d  %f %c %f %c\r\n", gps.lock, gpsHour,gpsMin,gpsSec,gps.nmea_longitude, gps.ns, gps.nmea_latitude, gps.ew);
            wait(.9);
        }
        else{
            pc.printf("No Lock\r\n");
            wait(1);    
        }        
    }//while(1)
}//main

Diff: GPSINT.h

Revision:
0:f3a7d716faea
Child:
1:c266b90b4c74
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPSINT.h	Sat Nov 01 13:27:11 2014 +0000
@@ -0,0 +1,102 @@
+/* GPSINT.h
+ * Copyright (c) 2014, jbradshaw (20141101)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+ 
+/* This GPSINT library class retrieves, parses, and updates variables using
+  a serial receive interrupt.  The library was written using the Trimble
+  Copernicus II moduls bus should work on any NMEA 4800 baud output device.
+  The relatively slow 4800 baud allows for plenty of processing time during
+  byte receptions in the interrupt.  Using the mbed LPC 100MHz unit, it takes
+  about 340us to process, and parse the 2 default GPGGA and GPZTG strings.*/
+
+#include "mbed.h"
+
+#ifndef GPSINT_H
+#define GPSINT_H
+
+#define PI (3.14159265359)
+#define GPSBUFSIZE  256       // GPS buffer size
+
+/**
+ * GPSINT Class.
+ */
+ 
+class GPSINT{
+public:
+    /**
+     * Constructor.
+     * @param gps - Serial port pins attached to the gps
+     */ 
+    GPSINT(PinName tx, PinName rx);
+    int nmea_validate(char *nmeastr);
+    void parseGPSString(char *GPSstrParse);
+    void GPSSerialRecvInterrupt(void);
+    float nmea_to_dec(float deg_coord, char nsew);
+    float calc_course_to(float pointLat, float pontLong);
+    double calc_dist_to_mi(float pointLat, float pontLong);
+    double calc_dist_to_ft(float pointLat, float pontLong);
+    double calc_dist_to_km(float pointLat, float pontLong);
+    double calc_dist_to_m(float pointLat, float pontLong);
+        
+    // GPSINT variables
+    char GPSbuf[GPSBUFSIZE];     // Receive buffer. 
+    char Temp_GPSbuf[GPSBUFSIZE];// Receive buffer. 
+    char GPSidx;               // Read by background, written by Int Handler.
+    int GPSstate;              //set when successful GPS string is received
+    
+    // calculated values
+    float dec_longitude;
+    float dec_latitude;
+    float altitude_ft;
+    
+    // GGA - Global Positioning System Fixed Data
+    float nmea_longitude;
+    float nmea_latitude;    
+    float utc_time;
+    char ns, ew;
+    int lock;
+    int satelites;
+    float hdop;
+    float msl_altitude;
+    char msl_units;
+    
+    // RMC - Recommended Minimmum Specific GNS Data
+    char rmc_status;
+    float speed_k;
+    float course_d;
+    int date;
+    
+    // GLL
+    char gll_status;
+    
+    // VTG - Course over ground, ground speed
+    float course_t; // ground speed true
+    char course_t_unit;
+    float course_m; // magnetic
+    char course_m_unit;
+    char speed_k_unit;
+    float speed_km; // speek km/hr
+    char speed_km_unit;
+private:
+    Serial _gps;
+};
+
+#endif /* GPSINT_H */
\ No newline at end of file