Revision 0:ce5f06c3895f, committed 2012-02-22

Comitter:

tylerjw

Date:

Wed Feb 22 03:52:43 2012 +0000

Child:

1:2ace7946a246

Commit message:

Version 0.1

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS/.lib	Wed Feb 22 03:52:43 2012 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/simon/programs/GPS/5zv5x
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS/GPS.cpp	Wed Feb 22 03:52:43 2012 +0000
@@ -0,0 +1,128 @@
+#include "GPS.h"
+
+GPS::GPS(PinName tx, PinName rx) : _gps(tx, rx) {
+    _gps.baud(4800);    
+    nmea_longitude = 0.0;
+    nmea_latitude = 0.0;
+    utc_time = 0;
+    ns = ' ';
+    ew = ' ';
+    lock = 0;
+    satelites = 0;
+    hdop = 0.0;
+    msl_altitude = 0.0;
+    msl_units = ' ';
+    
+    rmc_status = ' ';
+    ground_speed_k = 0.0;
+    ground_course_d = 0.0;
+    date = 0;     
+    
+    dec_longitude = 0.0;
+    dec_latitude = 0.0;   
+}
+
+float GPS::nmea_to_dec(float deg_coord, char nsew) {
+    int degree = (int)(deg_coord/100);
+    float minutes = deg_coord - degree*100;
+    float dec_deg = minutes / 60;
+    float decimal = degree + dec_deg;
+    if(nsew == 'S' || nsew == 'W') // return negative
+    {
+        decimal *= -1;
+    }
+    return decimal;
+}
+
+int GPS::sample() {
+    
+    while(1) {        
+        getline();
+
+        // Check if it is a GPGGA msg (matches both locked and non-locked msg)
+        if(sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%d,%d,%f,%f,%c", &utc_time, &nmea_latitude, &ns, &nmea_longitude, &ew, &lock, &satelites, &hdop, &msl_altitude, &msl_units) >= 1) { 
+            if(!lock) {   
+                return 0;
+            } else {
+                dec_latitude = nmea_to_dec(nmea_latitude, ns);
+                dec_longitude = nmea_to_dec(nmea_longitude, ew);
+                return 1;
+            }
+        }
+        // Check if it is a GPRMC msg)
+        else if(sscanf(msg, "GPRMC,%f,%c,%f,%c,%f,%c,%f,%f,%d", &utc_time, &rmc_status, &nmea_latitude, &ns, &nmea_longitude, &ew, &ground_speed_k, &ground_course_d, &date) >= 1) { 
+            if(!lock) {   
+                return 0;
+            } else {
+                dec_latitude = nmea_to_dec(nmea_latitude, ns);
+                dec_longitude = nmea_to_dec(nmea_longitude, ew);
+                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
+    for(int i=0; i<256; i++) {
+        msg[i] = _gps.getc();
+        if(msg[i] == '\r') {
+            msg[i] = 0;
+            return;
+        }
+    }
+    error("Overflowed message limit");
+}
+
+float GPS::get_msl_altitude() {
+    if(!lock) 
+        return 0.0;
+    else
+        return msl_altitude;
+}
+
+int GPS::get_satelites() {
+    if(!lock) 
+        return 0;
+    else
+        return satelites;
+}
+
+float GPS::get_nmea_longitude() {
+    if(!lock) 
+        return 0.0;
+    else
+        return nmea_longitude;
+}
+
+float GPS::get_dec_longitude() {
+    if(!lock) 
+        return 0.0;
+    else
+        return dec_longitude;
+}
+
+float GPS::get_nmea_latitude() {
+    if(!lock) 
+        return 0.0;
+    else
+        return nmea_latitude;
+}
+
+float GPS::get_dec_latitude() {
+    if(!lock) 
+        return 0.0;
+    else
+        return nmea_latitude;
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS/GPS.h	Wed Feb 22 03:52:43 2012 +0000
@@ -0,0 +1,79 @@
+/* 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 "mbed.h"
+
+#ifndef MBED_GPS_H
+#define MBED_GPS_H
+
+/**  A GPS interface for reading from a Globalsat EM-406 GPS Module */
+class GPS {
+public:
+
+    /** Create the GPS interface, connected to the specified serial port
+     */    
+    GPS(PinName tx, PinName rx);
+    
+    /** Sample the incoming GPS data, returning whether there is a lock
+     * 
+     * @return 1 if there was a lock when the sample was taken (and therefore .longitude and .latitude are valid), else 0
+     */
+    int sample();
+    float get_nmea_longitude();
+    float get_nmea_latitude();
+    float get_dec_longitude();
+    float get_dec_latitude();
+    float get_msl_altitude();
+    int get_satelites();
+    
+    
+private:
+    float nmea_to_dec(float, char);
+    float trunc(float v);
+    void getline();
+    
+    Serial _gps;
+    char msg[256];
+    
+    // calculated values
+    float dec_longitude;
+    float dec_latitude;
+    
+    // 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 ground_speed_k;
+    float ground_course_d;
+    int date;
+};
+
+#endif

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Feb 22 03:52:43 2012 +0000
@@ -0,0 +1,17 @@
+#include "mbed.h"
+#include "GPS.h"
+
+Serial pc(USBTX, USBRX);
+GPS gps(p9, p10);
+
+int main() {
+    while(1) {
+        if(gps.sample()) {
+            pc.printf("I'm at %f, %f\n", gps.get_dec_longitude(), gps.get_dec_latitude());
+            pc.printf("%d satelites used\n", gps.get_satelites());
+            pc.printf("altitude = %f M\n\n", gps.get_msl_altitude());
+        } else {
+            pc.printf("Oh Dear! No lock :(\n");
+        }
+    }
+}
\ No newline at end of file

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.lib	Wed Feb 22 03:52:43 2012 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/projects/libraries/svn/mbed/trunk@22
\ No newline at end of file