Cross platform C++ 11 NMEA Parser & GPS Framework
NemaTode is yet another lightweight generic NMEA parser.
It also comes with a GPS data interface to handle the most popular GPS NMEA sentences.
Confirmed on MSVC 2013 and GCC 4.8.4.
This is all you need to use the GPS NMEA sentence data.
NMEAParser parser;
GPSService gps(parser);
// (optional) Called when a sentence is valid syntax
parser.onSentence += [](const NMEASentence& nmea){
cout << "Received $" << nmea.name << endl;
};
// (optional) Called when data is read/changed
gps.onUpdate += [](GPSService& gps){
// There are *tons* of GPSFix properties
if( gps.fix.locked() ){
cout << " # Position: " << gps.fix.latitude << ", " << gps.fix.longitude << endl;
} else {
cout << " # Searching..." << endl;
}
};
// Send in a log file or a byte stream
try {
parser.readLine("FILL WITH A NMEA MESSAGE");
} catch (NMEAParseError&) {
// Syntax error, skip
}
##Features
-
NMEA Parsing of standard and custom sentences.
- Standard:
GPGGA, GPGSA, GPGSV, GPRMC, GPVTG
-
NMEA Generation of "standard" and custom sentences.
- SiRF Control sentences:
PSRF100, PSRF103
- SiRF Control sentences:
-
GPS Fix class to manage and organize all the GPS related data.
-
Flexible
- Stream data directly from a hardware byte stream
- Read log files, even if they are cluttered with other unrelated data.
- Easily hook into the parser to handle custom sentences and get their data.
- Simplified GPS data
-
C++ 11 features
- Those fancy event handlers...
- If you are on an embedded system... sorry. This might not work for you because of compiler restrictions. Make sure there is full support for lambdas and variadic templates. Tested GCC 4.8.4, confirmed.
NMEA is very popular with GPS. Unfortunately the GPS data is fragmented between many different NMEA sentences. Sometimes there is even conflicting information in them!
The underlying NMEAParser can read a byte stream from a hardware device or it can read log files with flexibility in the formatting. The accepted strings are...
"$[name:alphanum],[param[i]:alphanum],...(*alphanum[2]\r)\n"
The params allow '-' and any combination of whitespace.
The handler for "MYNMEA" is called. This is where you can catch the sentence and process it.
parser.setSentenceHandler("MYNMEA",[](const NMEASentence& nmea){
if( ! nmea.checksumOK() ){
// bad checksum, but valid syntax
}
if( nmea.parameters.size() < 3 ){
// missing data, throw something.
// catch it at the read*() call.
}
int mydata = parseInt(nmea.parameters[2]);
};
There are 2 ways to operate...
- LAX It will eat anything.
- Useful for reading log files.
- Call
readByte(), readBuffer(), readLine()
- STRICT It will throw errors on anything that's not explicitly NMEA.
- Call
readSentence()
- Call
"demo_simple.cpp"
- Just reads the GPS position data.
"demo_advanced.cpp"
- Reads all the data
- Sentence Generation
- Custom Sentence handling
Generation
NMEACommand mycmd;
mycmd.name = "MYCMD";
mycmd.message = "your,data,csv";
string nmea = mycmd.toString(); // Creates: $MYCMD,your,data,csv*15
There are 2 included NMEACommands that can configure a GPS.
-
PSRF103Configures message output ID and rate, and whether or not to use checksums. -
PSRF100Configures the UART serial connection (if the chip has one).
You can include NemaTode via CMake in our project. Your basic CMakeLists.txt file could look like:
cmake_minimum_required(VERSION 3.1)
project(MyProject)
find_package(NemaTode REQUIRED CONFIG)
add_executable(${PROJECT_NAME} mycode.cpp)
target_link_libraries(${PROJECT_NAME} NemaTode::NemaTode)
Available data when all 5 GPS sentences are received. If some are missing then some parameters will never change from their default values. All data is checked for consistency. For example, visible satellites can never be less than the tracking satellites, etc.
GPSFix
GPSAlmanac almanac;
GPSTimestamp timestamp;
char status; // Status: A=active, V=void (not locked)
uint8_t type; // Type: 1=none, 2=2d, 3=3d
uint8_t quality; // Quality (1-6)
double dilution; // Combination of Vertical & Horizontal
double horizontalDilution; // Horizontal dilution of precision, initialized to 10, best =1, worst = >20
double verticalDilution; // Vertical is less accurate
double altitude; // meters
double latitude; // degrees N
double longitude; // degrees E
double speed; // km/h
double travelAngle; // degrees true north (0-359)
int32_t trackingSatellites;
int32_t visibleSatellites;
bool locked(); // Whether or not the position is locked on, or accurate.
double horizontalAccuracy(); // Gets accuracy of position in meters
double verticalAccuracy();
bool hasEstimate(); // If no fix is available, this says the position data is close to a real fix.
std::chrono::seconds timeSinceLastUpdate(); // Returns time from last timestamp to right now, in seconds.
GPSSatellite
double snr; // Signal-to-noise ratio. 0-99 dB
uint32_t prn; // pseudo-random number. (basically a satellite id)
double elevation; // 0-90 deg
double azimuth; // 0-359 deg
GPSAlmanac
std::vector<GPSSatellite> satellites; // mapped by prn (id number)
double averageSNR();
double minSNR();
double maxSNR();
double percentComplete(); // if all the satellite information is loaded (0-100)
GPSTimestamp (UTC Time)
int32_t hour; // Parsed values from GPS
int32_t min;
double sec;
int32_t month;
int32_t day;
int32_t year;
double rawTime; // Values collected directly from the GPS
int32_t rawDate;
time_t getTime(); // Converts timestamp into Epoch time, seconds since 1/1/1970.
NMEA -> ME -> EM -> NEMA
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