Darren Ulrich
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 
Simon Ford
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
--- /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();
+ };
+