Richard Meadows / GPS_Alt

GPS with Altitude

Dependents:   Vodafone_SEDS

Fork of GPS by Simon Ford

GPS.cpp@1:586757e9ad1b, 2014-06-09 (annotated)

Committer:
richardemeadows
Date:
Mon Jun 09 16:48:04 2014 +0000
Revision:
1:586757e9ad1b
Parent:
0:15611c7938a3 
Added Altitude Decoding

Who changed what in which revision?

UserRevisionLine numberNew contents of line
simon 0:15611c7938a3 1 /* mbed EM-406 GPS Module Library
simon 0:15611c7938a3 2 * Copyright (c) 2008-2010, sford
simon 0:15611c7938a3 3 *
simon 0:15611c7938a3 4 * Permission is hereby granted, free of charge, to any person obtaining a copy
simon 0:15611c7938a3 5 * of this software and associated documentation files (the "Software"), to deal
simon 0:15611c7938a3 6 * in the Software without restriction, including without limitation the rights
simon 0:15611c7938a3 7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
simon 0:15611c7938a3 8 * copies of the Software, and to permit persons to whom the Software is
simon 0:15611c7938a3 9 * furnished to do so, subject to the following conditions:
simon 0:15611c7938a3 10 *
simon 0:15611c7938a3 11 * The above copyright notice and this permission notice shall be included in
simon 0:15611c7938a3 12 * all copies or substantial portions of the Software.
simon 0:15611c7938a3 13 *
simon 0:15611c7938a3 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
simon 0:15611c7938a3 15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
simon 0:15611c7938a3 16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
simon 0:15611c7938a3 17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
simon 0:15611c7938a3 18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
simon 0:15611c7938a3 19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
simon 0:15611c7938a3 20 * THE SOFTWARE.
simon 0:15611c7938a3 21 */
simon 0:15611c7938a3 22
simon 0:15611c7938a3 23 #include "GPS.h"
simon 0:15611c7938a3 24
simon 0:15611c7938a3 25 GPS::GPS(PinName tx, PinName rx) : _gps(tx, rx) {
simon 0:15611c7938a3 26 _gps.baud(4800);
simon 0:15611c7938a3 27 longitude = 0.0;
simon 0:15611c7938a3 28 latitude = 0.0;
simon 0:15611c7938a3 29 }
simon 0:15611c7938a3 30
simon 0:15611c7938a3 31 int GPS::sample() {
richardemeadows 1:586757e9ad1b 32 float time, hdop;
simon 0:15611c7938a3 33 char ns, ew;
simon 0:15611c7938a3 34 int lock;
simon 0:15611c7938a3 35
simon 0:15611c7938a3 36 while(1) {
simon 0:15611c7938a3 37 getline();
richardemeadows 1:586757e9ad1b 38
richardemeadows 1:586757e9ad1b 39 printf("MSG: %s\r\n", msg);
simon 0:15611c7938a3 40
simon 0:15611c7938a3 41 // Check if it is a GPGGA msg (matches both locked and non-locked msg)
richardemeadows 1:586757e9ad1b 42 if(sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%d,%d,%f,%f", &time, &latitude, &ns, &longitude, &ew, &lock, &satellites, &hdop, &altitude) >= 1) {
richardemeadows 1:586757e9ad1b 43
richardemeadows 1:586757e9ad1b 44 printf("LOCK: %d\r\n", lock);
richardemeadows 1:586757e9ad1b 45
richardemeadows 1:586757e9ad1b 46 if(lock == 1 || lock == 2 || lock == 6) { // GPS or Differential GPS or Dead Reckoning Fix
simon 0:15611c7938a3 47 float degrees = trunc(latitude / 100.0f);
simon 0:15611c7938a3 48 float minutes = latitude - (degrees * 100.0f);
simon 0:15611c7938a3 49 latitude = degrees + minutes / 60.0f;
richardemeadows 1:586757e9ad1b 50
richardemeadows 1:586757e9ad1b 51 degrees = trunc(longitude / 100.0f);
simon 0:15611c7938a3 52 minutes = longitude - (degrees * 100.0f);
simon 0:15611c7938a3 53 longitude = degrees + minutes / 60.0f;
richardemeadows 1:586757e9ad1b 54
richardemeadows 1:586757e9ad1b 55 if(ns == 'S') { latitude *= -1.0; }
richardemeadows 1:586757e9ad1b 56 if(ew == 'W') { longitude *= -1.0; }
richardemeadows 1:586757e9ad1b 57
simon 0:15611c7938a3 58 return 1;
richardemeadows 1:586757e9ad1b 59 } else {
richardemeadows 1:586757e9ad1b 60 longitude = 0.0;
richardemeadows 1:586757e9ad1b 61 latitude = 0.0;
richardemeadows 1:586757e9ad1b 62 altitude = 0.0;
richardemeadows 1:586757e9ad1b 63 return 0;
richardemeadows 1:586757e9ad1b 64 }
simon 0:15611c7938a3 65 }
simon 0:15611c7938a3 66 }
simon 0:15611c7938a3 67 }
simon 0:15611c7938a3 68
simon 0:15611c7938a3 69 float GPS::trunc(float v) {
simon 0:15611c7938a3 70 if(v < 0.0) {
simon 0:15611c7938a3 71 v*= -1.0;
simon 0:15611c7938a3 72 v = floor(v);
simon 0:15611c7938a3 73 v*=-1.0;
simon 0:15611c7938a3 74 } else {
simon 0:15611c7938a3 75 v = floor(v);
simon 0:15611c7938a3 76 }
simon 0:15611c7938a3 77 return v;
simon 0:15611c7938a3 78 }
simon 0:15611c7938a3 79
simon 0:15611c7938a3 80 void GPS::getline() {
simon 0:15611c7938a3 81 while(_gps.getc() != '$'); // wait for the start of a line
simon 0:15611c7938a3 82 for(int i=0; i<256; i++) {
simon 0:15611c7938a3 83 msg[i] = _gps.getc();
simon 0:15611c7938a3 84 if(msg[i] == '\r') {
simon 0:15611c7938a3 85 msg[i] = 0;
simon 0:15611c7938a3 86 return;
simon 0:15611c7938a3 87 }
simon 0:15611c7938a3 88 }
simon 0:15611c7938a3 89 error("Overflowed message limit");
simon 0:15611c7938a3 90 }