A tiny change to SKPanks GPS library to allow Ublox GPS modems to work.
Fork of GPS by
Diff: GPS.cpp
- Revision:
- 0:0f423a982334
- Child:
- 1:bcc48e322f84
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/GPS.cpp Fri Jul 27 15:07:00 2012 +0000 @@ -0,0 +1,65 @@ +/* GPS class for mbed Microcontroller + * Copyright (c) 2008, sford + */ + +#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"); +} +