Diff: GPS.cpp

Revision:

3:5eba63777267

diff -r e70394e9c959 -r 5eba63777267 GPS.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS.cpp	Thu Dec 05 23:57:55 2013 +0000
@@ -0,0 +1,137 @@
+/* mbed EM-406 GPS Module Library
+ * Copyright (c) 2008-2010, sford
+ *
+ * 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.
+ */
+
+#include "GPS.h"
+
+GPS::GPS(PinName tx, PinName rx) : _gps(tx, rx) {
+    _gps.baud(4800);
+    longitude = 0.0;
+    latitude = 0.0;
+}
+
+int GPS::sample() {
+    float time;
+    char ns, ew;
+    int lock;
+
+    //return 1; //testing by Jigar
+    while (1) {
+        getline();
+        //printf("\n\rentered the GPS.sample while loop \n\r %s\n\r", msg);
+        
+        
+        // Check if it is a GPGGA msg (matches both locked and non-locked msg)
+        // $GPGGA,000116.031,,,,,0,00,,,M,0.0,M,,0000*52
+        /*
+        eg3. $GPGGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh
+                        1       2     3  4       5 6  7  8   9  10 11 12 13  14   15
+            1    = UTC of Position
+            2    = Latitude
+            3    = N or S
+            4    = Longitude
+            5    = E or W
+            6    = GPS quality indicator (0=invalid; 1=GPS fix; 2=Diff. GPS fix)
+            7    = Number of satellites in use [not those in view]
+            8    = Horizontal dilution of position
+            9    = Antenna altitude above/below mean sea level (geoid)
+            10   = Meters  (Antenna height unit)
+            11   = Geoidal separation (Diff. between WGS-84 earth ellipsoid and
+                   mean sea level.  -=geoid is below WGS-84 ellipsoid)
+            12   = Meters  (Units of geoidal separation)
+            13   = Age in seconds since last update from diff. reference station
+            14   = Diff. reference station ID#
+            15   = Checksum
+
+        */
+       // if (sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%*d,%*d, %*f,%*f,%*f,%*f,%*f,%*f,%d ", &time, &latitude, &ns, &longitude, &ew, &lock) >= 1) {
+        if(sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%d", &time, &latitude, &ns, &longitude, &ew, &lock) >= 1) { 
+
+            if (!lock) {
+                longitude = 0.0;
+                latitude = 0.0;
+                return 0;
+            } else {
+                if (ns == 'S') {
+                    latitude  *= -1.0;
+                }
+                if (ew == 'W') {
+                    longitude *= -1.0;
+                }
+                float degrees = trunc(latitude / 100.0f);
+                float minutes = latitude - (degrees * 100.0f);
+                latitude = degrees + minutes / 60.0f;
+                 degrees = trunc(longitude / 100.0f ); //degrees = trunc(longitude / 100.0f * 0.01f);
+                minutes = longitude - (degrees * 100.0f);
+                longitude = degrees + minutes / 60.0f;
+                return 1;
+            }
+        }  
+    }
+}
+
+float GPS::trunc(float v) {
+    if (v < 0.0) {
+        v*= -1.0;
+        v = floor(v);
+        v*=-1.0;
+    } else {
+        v = floor(v);
+    }
+    return v;
+}
+
+void GPS::getline() {
+    
+    while (_gps.getc() != '$');   // wait for the start of a line
+    // printf("entered the getline loop\n\r");
+    for (int i=0; i<256; i++) {
+        msg[i] = _gps.getc();
+        if (msg[i] == '\r') {
+            msg[i] = 0;
+            return;
+        }
+    }
+    error("Overflowed message limit");
+}
+
+/*
+$GPRMC,000115.039,V,,,,,,,291006,,*2C
+$GPGGA,000116.031,,,,,0,00,,,M,0.0,M,,0000*52
+$GPGSA,A,1,,,,,,,,,,,,,,,*1E
+$GPGSV,3,1,12,20,00,000,,10,00,000,,31,00,000,,27,00,000,*7C
+$GPGSV,3,2,12,19,00,000,,07,00,000,,04,00,000,,24,00,000,*76
+$GPGSV,3,3,12,16,00,000,,28,00,000,,26,00,000,,29,00,000,*78
+$GPRMC,000116.031,V,,,,,,,291006,,*27
+$GPGGA,000117.035,,,,,0,00,,,M,0.0,M,,0000*57
+$GPGSA,A,1,,,,,,,,,,,,,,,*1E
+$GPRMC,000117.035,V,,,,,,,291006,,*22
+$GPGGA,000118.039,,,,,0,00,,,M,0.0,M,,0000*54
+$GPGSA,A,1,,,,,,,,,,,,,,,*1E
+$GPRMC,000118.039,V,,,,,,,291006,,*21
+$GPGGA,000119.035,,,,,0,00,,,M,0.0,M,,0000*59
+$GPGSA,A,1,,,,,,,,,,,,,,,*1E
+$GPRMC,000119.035,V,,,,,,,291006,,*2C
+$GPGGA,000120.037,,,,,0,00,,,M,0.0,M,,0000*51
+$GPGSA,A,1,,,,,,,,,,,,,,,*1E
+$GPRMC,000120.037,V,,,,,,,291006,,*24
+
+*/
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