longitude correction
Fork of GPS by
GPS.cpp
- Committer:
- simon
- Date:
- 2010-06-08
- Revision:
- 0:15611c7938a3
- Child:
- 1:8691c80f7ef5
File content as of revision 0:15611c7938a3:
/* 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; 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", &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 * 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 for(int i=0; i<256; i++) { msg[i] = _gps.getc(); if(msg[i] == '\r') { msg[i] = 0; return; } } error("Overflowed message limit"); }