4 pins(vcc,gnd,tx,rx)
Dependents: frdm_k64f_serialgps Low_Power_Long_Distance_IR_Vision_Robot Low_Power_Long_Distance_IR_Vision_Robot
Fork of GPS by
Diff: GPS.cpp
- Revision:
- 0:15611c7938a3
- Child:
- 1:1d60e6a0ffd9
diff -r 000000000000 -r 15611c7938a3 GPS.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/GPS.cpp Tue Jun 08 14:10:27 2010 +0000 @@ -0,0 +1,81 @@ +/* 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"); +}