C++ parser library for NMEA GPS data - pt. 1: ideas, concepts, early design

RE: C++ parser library for NMEA GPS data - pt. 1: ideas, concepts, early design

Jan Cumps — Tue, 06 Aug 2024 21:33:45 GMT

When integrating with a GPS, this could be the output of data collected by this parser:

+-- start --+
GLL source: gps. lat: 50.863354 lon: 7.042959, time: 21:33:19.000.
GSV source: gps.
sat prn: 24, elev: 88, azim: 83, snr: 18.
sat prn: 12, elev: 51, azim: 224, snr: 18.
sat prn: 19, elev: 41, azim: 83, snr: 18.
sat prn: 15, elev: 30, azim: 176, snr: 33.
GSV source: gps.
sat prn: 17, elev: 29, azim: 52, snr: 0.
sat prn: 10, elev: 23, azim: 293, snr: 18.
sat prn: 22, elev: 21, azim: 55, snr: 0.
sat prn: 25, elev: 18, azim: 235, snr: 0.
GSV source: gps.
sat prn: 23, elev: 18, azim: 254, snr: 0.
sat prn: 32, elev: 16, azim: 317, snr: 0.
sat prn: 13, elev: 11, azim: 148, snr: 14.
sat prn: 49, elev: 31, azim: 179, snr: 35.
GSV source: glonass.
sat prn: 73, elev: 69, azim: 294, snr: 0.
sat prn: 71, elev: 58, azim: 252, snr: 0.
sat prn: 80, elev: 43, azim: 53, snr: 17.
sat prn: 72, elev: 33, azim: 323, snr: 0.
GSV source: glonass.
sat prn: 70, elev: 26, azim: 193, snr: 30.
sat prn: 74, elev: 27, azim: 261, snr: 0.
sat prn: 82, elev: 24, azim: 80, snr: 0.
sat prn: 81, elev: 21, azim: 29, snr: 0.
GSV source: glonass.
sat prn: 83, elev: 6, azim: 118, snr: 0.
sat prn: 0, elev: 0, azim: 0, snr: 0.
sat prn: 0, elev: 0, azim: 0, snr: 0.
sat prn: 0, elev: 0, azim: 0, snr: 0.
RMC source: gps. lat: 50.863354 lon: 7.042968. 21:33:20.000. 2024-08-06.
+-- end --+

The output above is generated by a Teseo connected to a Pico via I2C, running this example: https://github.com/jancumps/pico_gps_teseo/blob/7aa9c509de7ac34749df427e6a78523f2eca32fe/teseo_with_nmea_parse.cpp

RE: C++ parser library for NMEA GPS data - pt. 1: ideas, concepts, early design

Jan Cumps — Thu, 01 Aug 2024 14:09:39 GMT

The initial version had custom classes to hold dates and times. I've replaced those by these standard C++ classes:

std::chrono::year_month_day

std::chrono::hh_mm_ss
(it can actually hold subseconds)

You may find remnants of the original date and time_ms in the text of the posts.

RE: C++ parser library for NMEA GPS data - pt. 1: ideas, concepts, early design

Jan Cumps — Wed, 31 Jul 2024 18:40:46 GMT

The attached archive contains the library sources and a test bed. It's a zipped Eclipse project.
Only files needed in a project are nmea.h and nmea.cpp.

Your toolchain must support - and needs to be set minimal to - the C++ standard -std=c++23

As soon as I've figured out how to make both Teseo GPS library and this NMEA parser library available on GitHub,
in a way that makes it easy to use them separate or together,
I'll create the repository online.

RE: C++ parser library for NMEA GPS data - pt. 1: ideas, concepts, early design

shabaz — Tue, 30 Jul 2024 23:20:27 GMT

That looks great! And clean having the separate classes per important NMEA message type.

Personally I much prefer this technique compared to the existing libraries I've seen. It seems very straightforward from the user perspective, to have the objects populate from the reply content as you've shown. Also, another benefit from the separation that you did; it is possible for users to test their projects in different countries virtually : ) or replay scenarios, by populating the reply strings themselves, i.e. as test vectors.