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Forum Index : Microcontroller and PC projects : GPRMC vs GNRMC

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palcal

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Joined: 12/10/2011
Location: Australia
Posts: 1873
Posted: 09:45pm 16 Oct 2024
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Has the NMEA sentence changed from GPRMC to GNRMC. I have some V.KEL 2828U8 GPS modules that only work with GNRMC whereas the older U7 model worked ok with GPRMC. I recently fitted a NEO6M to one of Geoff's GPS trackers because the module has battery backup and it won't work whereas the V.Kel 2828U7 works ok.
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6089
Posted: 10:05pm 16 Oct 2024
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What device and firmware version?
The later firmware should handle both CPRMC and GNRMC
  Quote  The sentences interpreted are GPRMC,
GNRMC, GPGGA and GNGGA.


Jim
VK7JH
MMedit   MMBasic Help
 
goc30

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Joined: 12/04/2017
Location: France
Posts: 427
Posted: 03:47am 17 Oct 2024
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https://blog.bliley.com/the-differences-between-the-5-gnss-satellite-network-constellations



The first two characters after the $ sign identify the origin of the signal. The main prefixes are:
BD or GB = BEIDOU GA = GALILEO GP = GPS GL = GLONASS
The GN prefix is ​​used in the case of mixed signals, for example GPS + GLONASS.
 
palcal

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Location: Australia
Posts: 1873
Posted: 05:01am 17 Oct 2024
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@ Jim, not on a MM or Pico it is Geoff's "GPS Tracker" from his web site. I had a look at the source file but would not know where to start. The code is probably 10 years old. However a few months back I found that the V.KEL2828 U8 version would only work with the Picomite and not the MM unless I used GNRMC and not GPRMC in my code. I don't think the MM has the GPS function like the Picomite does. I don't know how hard it would be for Geoff to update the tracker code, fairly easy I would think.
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
palcal

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Posted: 05:07am 17 Oct 2024
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@ goc30,  see HERE .  I think the newer V.KEL U8 version only outputs the
GNRMC sentence not GPRMC>
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
TassyJim

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Posted: 06:20am 17 Oct 2024
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This is a good time to put a picomite on a daughter-board and be future proofed.
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palcal

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Posts: 1873
Posted: 06:25am 17 Oct 2024
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I've already made a PicoMite Backpack PCB, but this is not a Picomite the tracker uses an MX250 chip.
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
TassyJim

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Posted: 06:49am 17 Oct 2024
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My suggestion is to remove the MX250 and fit a picomite. You obviously can't just plug it in so an adapter board is required.
The pins on the pico are very configurable so you can use pins close to the MX250 ones to make the adapter board easier to do.
Once the pico is fitted, you can program an equivalent program in MMBasic.

Jim
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palcal

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Posted: 07:52am 17 Oct 2024
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Thats a lot of trouble to go to, I can just use a V.KEL2828 U7 version that works ok with the tracker, I was just trying the NEO6M because it has battery backup for a faster start, not that it is all that necessary.
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
goc30

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Joined: 12/04/2017
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Posted: 08:53am 17 Oct 2024
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  palcal said  @ goc30,  see HERE .  I think the newer V.KEL U8 version only outputs the
GNRMC sentence not GPRMC>


Of course, it depends on the manufacturer of the GPS card, and even on the date of manufacture. Chinese suppliers, for the most part, have been integrating GLONASS for a few years, while US manufacturers ignore the russian network. One day you receive a card with an old circuit that sends GPRMC, and a few days later, the same supplier will send a card with a circuit recoding GNRMC. And if it's the opposite, it's because the supplier is selling off its old stock
 
palcal

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Posts: 1873
Posted: 11:50pm 17 Nov 2024
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I finally got this working OK. Geoff was unable to make changes to the original Tracker software but suggested I change the parameters in the GPS module using U_BLOX  U_Centre.
It was a bit of a learning curve but I successfully changed the baud rate and the ability to receive GPRMC.
Thanks Geoff.
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
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