nnog / neogps

NMEA and ublox GPS parser for Arduino, configurable to use as few as 10 bytes of RAM

NeoGPS

This fully-configurable Arduino library uses minimal RAM, PROGMEM and CPU time, requiring as few as 10 bytes of RAM, 866 bytes of PROGMEM, and less than 1mS of CPU time per sentence.

It supports the following protocols and messages:

NMEA 0183

• GPGGA - System fix data
• GPGLL - Geographic Latitude and Longitude
• GPGSA - DOP and active satellites
• GPGST - Pseudo Range Error Statistics
• GPGSV - Satellites in View
• GPRMC - Recommended Minimum specific GPS/Transit data
• GPVTG - Course over ground and Ground speed
• GPZDA - UTC Time and Date

The "GP" prefix usually indicates an original GPS source. NeoGPS parses all Talker IDs, including

• "GL" (GLONASS),
• "BD" or "GB" (BeiDou),
• "GA" (Galileo), and
• "GN" (mixed)

This means that GLRMC, GBRMC or BDRMC, GARMC and GNRMC from the latest GPS devices (e.g., ublox M8N) will also be correctly parsed. See discussion of Talker IDs in Configurations.

Most applications can be fully implemented with the standard NMEA messages above. They are supported by almost all GPS manufacturers. Additional messages can be added through derived classes (see ublox and Garmin sections below).

Most applications will use this simple, familiar loop structure:

NMEAGPS gps;
gps_fix fix;

void loop()
{
  while (gps.available( gps_port )) {
    fix = gps.read();
    doSomeWork( fix );
  }
}

For more information on this loop, see the Usage section on the Data Model page.

(This is the plain Arduino version of the CosaGPS library for Cosa.)

Goals

In an attempt to be reusable in a variety of different programming styles, this library supports:

• resource-constrained environments (e.g., ATTINY targets)
• sync or async operation (reading in loop() vs interrupt processing)
• event or polling (deferred handling vs. continuous calls in loop())
• coherent fixes (merged from multiple sentences) vs. individual sentences
• optional buffering of fixes
• optional floating point
• configurable message sets, including hooks for implementing proprietary NMEA messages
• configurable message fields
• multiple protocols from same device
• any kind of input stream (Serial, NeoSWSerial, I2C, PROGMEM arrays, etc.)

Inconceivable!

Don't believe it? Check out these detailed sections:

Section	Description
License	The Fine Print
Installing	Copying files
Data Model	How to parse and use GPS data
Configurations	Tailoring NeoGPS to your needs
Performance	37% to 72% faster! Really!
RAM requirements	Doing it without buffers!
Program Space requirements	Making it fit
Examples	Programming styles
Troubleshooting	Troubleshooting
Extending NeoGPS	Using specific devices
ublox	ublox-specific code
Garmin	Garmin-specific code
Tradeoffs	Comparing to other libraries
Acknowledgements	Thanks!