Sukkin Pang / GPS

GPS for mbed

Dependents:   ecu_reader gsm_SET

GPS.cpp@0:0f423a982334, 2012-07-27 (annotated)

Committer:
pangsk
Date:
Fri Jul 27 15:07:00 2012 +0000
Revision:
0:0f423a982334
[mbed] converted /ecu_reader/GPS

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