Nicholas Herriot / GPS

A tiny change to SKPanks GPS library to allow Ublox GPS modems to work.

Fork of GPS by Sukkin Pang

GPS.cpp@1:bcc48e322f84, 2013-07-25 (annotated)

Committer:
nherriot
Date:
Thu Jul 25 13:06:07 2013 +0000
Revision:
1:bcc48e322f84
Parent:
0:0f423a982334 
Change required to allow UBLOX GPS module to work properly.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
pangsk 0:0f423a982334 1 /* GPS class for mbed Microcontroller
pangsk 0:0f423a982334 2 * Copyright (c) 2008, sford
pangsk 0:0f423a982334 3 */
pangsk 0:0f423a982334 4
pangsk 0:0f423a982334 5 #include "GPS.h"
pangsk 0:0f423a982334 6
pangsk 0:0f423a982334 7 GPS::GPS(PinName tx, PinName rx) : _gps(tx, rx) {
nherriot 1:bcc48e322f84 8 _gps.baud(9000); // higher baud rate need to support ublox gps chip
nherriot 1:bcc48e322f84 9 // _gps.baud(4800);
pangsk 0:0f423a982334 10 longitude = 0.0;
pangsk 0:0f423a982334 11 latitude = 0.0;
pangsk 0:0f423a982334 12 }
pangsk 0:0f423a982334 13
pangsk 0:0f423a982334 14
pangsk 0:0f423a982334 15 int GPS::sample() {
pangsk 0:0f423a982334 16 float time;
pangsk 0:0f423a982334 17 char ns, ew;
pangsk 0:0f423a982334 18 int lock;
pangsk 0:0f423a982334 19
pangsk 0:0f423a982334 20 while(1) {
pangsk 0:0f423a982334 21 getline();
pangsk 0:0f423a982334 22
pangsk 0:0f423a982334 23 // Check if it is a GPGGA msg (matches both locked and non-locked msg)
pangsk 0:0f423a982334 24 if(sscanf(msg, "GPGGA,%f,%f,%c,%f,%c,%d", &time, &latitude, &ns, &longitude, &ew, &lock) >= 1) {
pangsk 0:0f423a982334 25 if(!lock) {
pangsk 0:0f423a982334 26 longitude = 0.0;
pangsk 0:0f423a982334 27 latitude = 0.0;
pangsk 0:0f423a982334 28 return 0;
pangsk 0:0f423a982334 29 } else {
pangsk 0:0f423a982334 30 if(ns == 'S') { latitude *= -1.0; }
pangsk 0:0f423a982334 31 if(ew == 'W') { longitude *= -1.0; }
pangsk 0:0f423a982334 32 float degrees = trunc(latitude / 100.0f);
pangsk 0:0f423a982334 33 float minutes = latitude - (degrees * 100.0f);
pangsk 0:0f423a982334 34 latitude = degrees + minutes / 60.0f;
pangsk 0:0f423a982334 35 degrees = trunc(longitude / 100.0f * 0.01f);
pangsk 0:0f423a982334 36 minutes = longitude - (degrees * 100.0f);
pangsk 0:0f423a982334 37 longitude = degrees + minutes / 60.0f;
pangsk 0:0f423a982334 38 return 1;
pangsk 0:0f423a982334 39 }
pangsk 0:0f423a982334 40 }
pangsk 0:0f423a982334 41 }
pangsk 0:0f423a982334 42 }
pangsk 0:0f423a982334 43
pangsk 0:0f423a982334 44 float GPS::trunc(float v) {
pangsk 0:0f423a982334 45 if(v < 0.0) {
pangsk 0:0f423a982334 46 v*= -1.0;
pangsk 0:0f423a982334 47 v = floor(v);
pangsk 0:0f423a982334 48 v*=-1.0;
pangsk 0:0f423a982334 49 } else {
pangsk 0:0f423a982334 50 v = floor(v);
pangsk 0:0f423a982334 51 }
pangsk 0:0f423a982334 52 return v;
pangsk 0:0f423a982334 53 }
pangsk 0:0f423a982334 54
pangsk 0:0f423a982334 55 void GPS::getline() {
pangsk 0:0f423a982334 56 while(_gps.getc() != '$'); // wait for the start of a line
pangsk 0:0f423a982334 57 for(int i=0; i<256; i++) {
pangsk 0:0f423a982334 58 msg[i] = _gps.getc();
pangsk 0:0f423a982334 59 if(msg[i] == '\r') {
pangsk 0:0f423a982334 60 msg[i] = 0;
pangsk 0:0f423a982334 61 return;
pangsk 0:0f423a982334 62 }
pangsk 0:0f423a982334 63 }
pangsk 0:0f423a982334 64 error("Overflowed message limit");
pangsk 0:0f423a982334 65 }
pangsk 0:0f423a982334 66