William Obiri-Danso / GPS-timef

Library for the EM-406 GPS module with time export support added

Fork of GPS by Simon Ford

GPS.cpp@3:145bdf751843, 2018-03-04 (annotated)

Committer:
WilliamO7
Date:
Sun Mar 04 22:37:29 2018 +0000
Revision:
3:145bdf751843
Parent:
2:0d0ce3b0052d
Child:
4:147f30d69bf6
remove straight time conversion

Who changed what in which revision?

UserRevisionLine numberNew contents of line
WilliamO7 1:bc118a161471 1 /* mbed EM-406 GPS Module Library with time return support
simon 0:15611c7938a3 2 * Copyright (c) 2008-2010, sford
WilliamO7 1:bc118a161471 3 * Copyright (c) 2018 WilliamO7
simon 0:15611c7938a3 4 *
simon 0:15611c7938a3 5 * Permission is hereby granted, free of charge, to any person obtaining a copy
simon 0:15611c7938a3 6 * of this software and associated documentation files (the "Software"), to deal
simon 0:15611c7938a3 7 * in the Software without restriction, including without limitation the rights
simon 0:15611c7938a3 8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
simon 0:15611c7938a3 9 * copies of the Software, and to permit persons to whom the Software is
simon 0:15611c7938a3 10 * furnished to do so, subject to the following conditions:
simon 0:15611c7938a3 11 *
simon 0:15611c7938a3 12 * The above copyright notice and this permission notice shall be included in
simon 0:15611c7938a3 13 * all copies or substantial portions of the Software.
simon 0:15611c7938a3 14 *
simon 0:15611c7938a3 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
simon 0:15611c7938a3 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
simon 0:15611c7938a3 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
simon 0:15611c7938a3 18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
simon 0:15611c7938a3 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
simon 0:15611c7938a3 20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
simon 0:15611c7938a3 21 * THE SOFTWARE.
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;
WilliamO7 1:bc118a161471 28 latitude = 0.0;
WilliamO7 3:145bdf751843 29 time_utc = 0.0;
simon 0:15611c7938a3 30 }
simon 0:15611c7938a3 31
simon 0:15611c7938a3 32 int GPS::sample() {
simon 0:15611c7938a3 33 float time;
simon 0:15611c7938a3 34 char ns, ew;
simon 0:15611c7938a3 35 int lock;
simon 0:15611c7938a3 36
simon 0:15611c7938a3 37 while(1) {
simon 0:15611c7938a3 38 getline();
simon 0:15611c7938a3 39
simon 0:15611c7938a3 40 // Check if it is a GPGGA msg (matches both locked and non-locked msg)
simon 0:15611c7938a3 41 if(sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%d", &time, &latitude, &ns, &longitude, &ew, &lock) >= 1) {
simon 0:15611c7938a3 42 if(!lock) {
simon 0:15611c7938a3 43 longitude = 0.0;
WilliamO7 1:bc118a161471 44 latitude = 0.0;
WilliamO7 2:0d0ce3b0052d 45 time_utc = "";
simon 0:15611c7938a3 46 return 0;
simon 0:15611c7938a3 47 } else {
simon 0:15611c7938a3 48 if(ns == 'S') { latitude *= -1.0; }
simon 0:15611c7938a3 49 if(ew == 'W') { longitude *= -1.0; }
simon 0:15611c7938a3 50 float degrees = trunc(latitude / 100.0f);
simon 0:15611c7938a3 51 float minutes = latitude - (degrees * 100.0f);
simon 0:15611c7938a3 52 latitude = degrees + minutes / 60.0f;
simon 0:15611c7938a3 53 degrees = trunc(longitude / 100.0f * 0.01f);
simon 0:15611c7938a3 54 minutes = longitude - (degrees * 100.0f);
simon 0:15611c7938a3 55 longitude = degrees + minutes / 60.0f;
WilliamO7 3:145bdf751843 56 time_utc = time;
simon 0:15611c7938a3 57 return 1;
simon 0:15611c7938a3 58 }
simon 0:15611c7938a3 59 }
simon 0:15611c7938a3 60 }
simon 0:15611c7938a3 61 }
simon 0:15611c7938a3 62
simon 0:15611c7938a3 63 float GPS::trunc(float v) {
simon 0:15611c7938a3 64 if(v < 0.0) {
simon 0:15611c7938a3 65 v*= -1.0;
simon 0:15611c7938a3 66 v = floor(v);
simon 0:15611c7938a3 67 v*=-1.0;
simon 0:15611c7938a3 68 } else {
simon 0:15611c7938a3 69 v = floor(v);
simon 0:15611c7938a3 70 }
simon 0:15611c7938a3 71 return v;
simon 0:15611c7938a3 72 }
simon 0:15611c7938a3 73
simon 0:15611c7938a3 74 void GPS::getline() {
simon 0:15611c7938a3 75 while(_gps.getc() != '$'); // wait for the start of a line
simon 0:15611c7938a3 76 for(int i=0; i<256; i++) {
simon 0:15611c7938a3 77 msg[i] = _gps.getc();
simon 0:15611c7938a3 78 if(msg[i] == '\r') {
simon 0:15611c7938a3 79 msg[i] = 0;
simon 0:15611c7938a3 80 return;
simon 0:15611c7938a3 81 }
simon 0:15611c7938a3 82 }
simon 0:15611c7938a3 83 error("Overflowed message limit");
WilliamO7 2:0d0ce3b0052d 84 }