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Forum Index : Microcontroller and PC projects : Pico GPS for Matherp
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lew247 Guru  Joined: 23/12/2015 Location: United KingdomPosts: 1702 |
With the Picomite OPEN comspec$ AS GPS [,timezone_offset] [,monitor] it interprets the GPRMC, GNRMC, GPCGA and GNCGA sentences Do you know if this is ONLY for GPS, or does it decode them from Galileo, Beidou and Glonass as well? |
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thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 4311 |
Obviously I'm not Peter, but I've looked at the code and there is no sign that it distinguishes between satellite constellations. I would *imagine* that the GPS package (which presumably includes its own micro-controller) is responsible for ironing out any differences in protocols between the different constellations (if there even are any) and presenting a uniform interface via the serial comms which is then handled by the 'mite GPS code. Best wishes, Tom Edited 2022-08-26 18:48 by thwill MMBasic for Linux, Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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Sasquatch Guru Joined: 08/05/2020 Location: United StatesPosts: 377 |
The $GPRMC and $GPGGA messages are GPS specific messages. The $GNRMC and $GNGGA messages are more general GNSS (Global Navigation Satellite System) navigation messages. To answer your question, the current PicoMite firmware will NOT handle messages specific to the Galileo, Beidou and Glonass GNSS systems. However, most of the modern receivers will output the GNxxx messages when tracking multiple GNSS systems. So if your "GPS" receiver is enabled to track satellites from the above listed systems chances are it will output the $GNxxx messages or can be configured to do so. I have tested the PicoMite with the Adafruit "Ultimate GPS" module as well as the ublox NEO-M8 and NEO-M9 receivers and they all work with the current firmware. The default configuration for the ublox receivers is to track multiple GNSS systems and output the $GNxxx messages. I suspect that this is also true of other modern receivers. I have some older receivers that I will test as well. As of PicoMite firmware version V5.07.05b17, Peter made some changes to the GPS code to use double precision variables enabling higher resolution position information from newer GNSS receivers. After having a closer look at the code, I now realize there are other limitations. The current GPS parsing code is in some respects treating the comma delimited messages as a fixed number of digits. It is also using some fixed point math likely originally intended for older 8-Bit micro-controllers. I am currently doing some research and will submit some updated GNSS parsing code after testing. Edited 2022-08-27 00:06 by Sasquatch -Carl |
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