A GPS serial interrupt service routine that has an on the fly nmea parser. Works with a STM32F411RE and a Adafruit GPS logger.
Dependents: Bicycl_Computer_NUCLEO-F411RE Bicycl_Computer_NUCLEO-L476RG
Fork of GPS by
main.cpp
#include "mbed.h" #include "GPSISR.h" #define PIN_RX_GPS PA_12 //GPS Shield RX pin #define PIN_TX_GPS PA_11 //GPS Shield TX pin Serial pc(USBTX, USBRX); // Set up serial interrupe service handler for gps characters. GPS MyGPS(PIN_TX_GPS,PIN_RX_GPS, 9600); int main() { while (1) { if (MyGPS.dataready()) { MyGPS.read(); pc.printf("NMEA has valid data"); pc.printf("Sats : %d \n", MyGPS.buffer.satellites); pc.printf("%d-%d-%d\n", MyGPS.buffer.month, MyGPS.buffer.day, MyGPS.buffer.year); pc.printf("%d:%d:%d\n", MyGPS.buffer.hours, MyGPS.buffer.minutes, MyGPS.buffer.seconds); } else { pc.printf("NMEA has no valid data"); } } }
Diff: nmea.h
- Revision:
- 1:4b5ffae743c0
- Child:
- 5:c5f700c1e1af
diff -r 15611c7938a3 -r 4b5ffae743c0 nmea.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/nmea.h Fri Feb 10 17:57:45 2017 +0000 @@ -0,0 +1,104 @@ +/* + File: nmea.h + Version: 0.1.0 + Date: Feb. 23, 2013 + License: GPL v2 + + NMEA GPS content parser + + **************************************************************************** + Copyright (C) 2013 Radu Motisan <radu.motisan@gmail.com> + + http://www.pocketmagic.net + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + **************************************************************************** + */ +//#include "../timeout.h" + + + +class NMEA { + + private: + bool m_bFlagRead, // flag used by the parser, when a valid sentence has begun + m_bFlagDataReady; // valid GPS fix and data available, user can call reader functions + char tmp_words[20][15], // hold parsed words for one given NMEA sentence + tmp_szChecksum[15]; // hold the received checksum for one given NMEA sentence + + // will be set to true for characters between $ and * only + bool m_bFlagComputedCks ; // used to compute checksum and indicate valid checksum interval (between $ and * in a given sentence) + int m_nChecksum ; // numeric checksum, computed for a given sentence + bool m_bFlagReceivedCks ; // after getting * we start cuttings the received checksum + int index_received_checksum ; // used to parse received checksum + + // word cutting variables + int m_nWordIdx , // the current word in a sentence + m_nPrevIdx, // last character index where we did a cut + m_nNowIdx ; // current character index + + // globals to store parser results + float res_fLongitude; // GPRMC and GPGGA + float res_fLatitude; // GPRMC and GPGGA + unsigned char res_nUTCHour, res_nUTCMin, res_nUTCSec, // GPRMC and GPGGA + res_nUTCDay, res_nUTCMonth, res_nUTCYear; // GPRMC + int res_nSatellitesUsed; // GPGGA + float res_fAltitude; // GPGGA + float res_fSpeed; // GPRMC + float res_fBearing; // GPRMC + + // the parser, currently handling GPRMC and GPGGA, but easy to add any new sentences + void parsedata(); + // aux functions + int digit2dec(char hexdigit); + float string2float(char* s); + int mstrcmp(const char *s1, const char *s2); + float trunc(float v); + + public: + // constructor, initing a few variables + NMEA() { + m_bFlagRead = false; //are we in a sentence? + m_bFlagDataReady = false; //is data available? + } + + /* + * The serial data is assembled on the fly, without using any redundant buffers. + * When a sentence is complete (one that starts with $, ending in EOL), all processing is done on + * this temporary buffer that we've built: checksum computation, extracting sentence "words" (the CSV values), + * and so on. + * When a new sentence is fully assembled using the fusedata function, the code calls parsedata. + * This function in turn, splits the sentences and interprets the data. Here is part of the parser function, + * handling both the $GPRMC NMEA sentence: + */ + int fusedata(char c); + + + // READER functions: retrieving results, call isdataready() first + bool isdataready(); + int getHour(); + int getMinute(); + int getSecond(); + int getDay(); + int getMonth(); + int getYear(); + float getLatitude(); + float getLongitude(); + int getSatellites(); + float getAltitude(); + float getSpeed(); + float getBearing(); + }; +