Mbed with low-cost serial BR355 GPS using RS232 breakout and PS/2 breakout for power.

Dependencies:   mbed

Files at this revision

API Documentation at this revision

Comitter:
snavare3
Date:
Fri Feb 25 20:02:14 2011 +0000
Commit message:

Changed in this revision

GPS.cpp Show annotated file Show diff for this revision Revisions of this file
GPS.h Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show annotated file Show diff for this revision Revisions of this file
diff -r 000000000000 -r 98ae71628dbf GPS.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS.cpp	Fri Feb 25 20:02:14 2011 +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
+
+*/
\ No newline at end of file
diff -r 000000000000 -r 98ae71628dbf GPS.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/GPS.h	Fri Feb 25 20:02:14 2011 +0000
@@ -0,0 +1,57 @@
+/* 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();
+    
+    /** The longitude (call sample() to set) */
+    float longitude;
+
+    /** The latitude (call sample() to set) */
+    float latitude;
+    
+private:
+    float trunc(float v);
+    void getline();
+    
+    Serial _gps;
+    char msg[256];
+
+};
+
+#endif
diff -r 000000000000 -r 98ae71628dbf main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Feb 25 20:02:14 2011 +0000
@@ -0,0 +1,41 @@
+#include "mbed.h"
+#include "GPS.h"
+
+Serial pc(USBTX, USBRX);
+GPS gps(p9, p10);
+
+int main() {
+    while(1) {
+        //wait(0.1);
+        //pc.printf("\nHello world\n\r");
+        //printf ("\n\r the value of GPS sample is : %d\n\r", gps.sample());
+        if(gps.sample()) {
+            pc.printf("I'm at %f, %f\n\r", gps.longitude, gps.latitude);
+        } else {
+            pc.printf("Oh Dear! No lock :(\n\r");
+        }
+    }
+}
+
+
+/*
+$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
+*/
\ No newline at end of file
diff -r 000000000000 -r 98ae71628dbf mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Fri Feb 25 20:02:14 2011 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/029aa53d7323