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Old 14-01-2025, 14:08   #1
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$FRPOS / GPS buddy sentence not recognized

Hi,

I've been trying to show $FRPOS locations in OpenCPN. These sentences are generated by an ESP32, and then put into OpenCPN on the usb-comport.

The sentences are generated with the protocol as shown in the link below:
https://www.traccar.org/protocol/502...rotocol200.pdf

And in the OpenCPN wiki, there is also mentioning of this nmea sentence:
https://mail.opencpn.org/wiki/dokuwi..._buddy_via_ais

As mentioned in the subject of this thread, I don't get this to work. The position of this FRPOS / GPS buddy is not shown on my maps. Is there anybody that is using this sentence with succes?

Regards,
Wouter
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Old 14-01-2025, 17:32   #2
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Re: $FRPOS / GPS buddy sentence not recognized

AldebaranNL...


If you will send us some of your NMEA log files (use VDR to capture them), we can check it out.


Thanks
Dave
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Old 14-01-2025, 21:13   #3
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Re: $FRPOS / GPS buddy sentence not recognized

Simple test using the following sentence
Code:
$FRPOS,4230.10,S,15000.95,E,0.0,5.43,315.0,150125,142203.000,ConBrio*07
displays correctly on all versions of OpenCPN from 5.2 including latest beta 5.11

However minor bugs in the target display, outlined in the attached screenshot.

1. Incorrect AIS Vessel Type/Nav Status text: "GPS Gate Buddy, Underway using engine"
2. Incorrect parsing/display of date.
3. Missing Speed & Heading
4. Text formatting for CPA/TCPA

Clearly, similar to the Garmin host regression, few people use this.
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Old 15-01-2025, 00:47   #4
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Re: $FRPOS / GPS buddy sentence not recognized

Thanks for the quick reply. I'll try the nmea sentence that stevead supplied this evenening. Also try to make a log-file and supply that here.

The sentence that I tried through the ESP32 is the following:
$FRPOS,5303,N,0540,E,0.9,0.2,19.0,120125,153845,to pmark*15

This is then shown in the debug monitor by:
<GREEN>16:49:33 (COM5) $FRPOS,5303,N,0540,E,2.8,0.6,29.0,120125,153845,to pmark*15<0x0D><0x0A>

It seems that the checksum is not correct. I will look into that also this evenening. This shouldn't be an issue, as I switched off the checksum-check in the communications tab. And this does seem to work for a custom GPRMC sentence that I send through this ESP32 for comparison. But it could be that the FRPOS checksum-check cannot be turned off.

regards,
Wouter
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Old 15-01-2025, 01:41   #5
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Re: $FRPOS / GPS buddy sentence not recognized

The correct checksum can be calculated in several places, here is one.
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Old 15-01-2025, 13:14   #6
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Re: $FRPOS / GPS buddy sentence not recognized

Hi,

I've got position and the green buoy on my chart!! So it is working now. It seems that the checksum need to be correct. And cannot be discarded as with other nmea sentences.

Thanks for the help!

regards,
Wouter
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Old 15-01-2025, 16:56   #7
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Re: $FRPOS / GPS buddy sentence not recognized

Quote:
It seems that the checksum need to be correct. And cannot be discarded as with other nmea sentences.
Hakan, you've more knowledge on this than I. Does the "ignore checksum" option only apply to NMEA 0183 sentences that are parsed with Sam Blackburn's NMEA 0183 library but not to anything parsed in the AIS codebase such as VDO, VDM, DSC & FRPOS sentences ?
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