Ultimate GPS MTK3339 Remove $PGTOP sentence

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spoz
 
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Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by spoz »

Does anyone know if it's possible to disable output of the $PGTOP sentence from the MTK3339 V3 GPS module?

I just dropped it in as a replacement for the MTK3329 and it works fine - all the other commands work as expected but I still get a PGTOP sentence telling me I don't have an antenna connected - which I am very well aware of.

Any help would be greatly appreciated!

spoz
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by spoz »

Nobody knows?

Can anyone tell me about upgrading the firmware as a possible solution? I need the ability to output NMEA above 18000m altitude so I'm reluctant to do any firmware flashing unless the new firmware is guaranteed to use an OR rule on the COCOM limits...

JD3
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by JD3 »

Try the manufacturer's website - there are several downloads available.
Or try contacting them. I do not have the GPS module, so all I can do is point to a possible solution.

http://www.gtop-tech.com/jsf/moduleprod ... 5e4c56a03f

adafruit
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by adafruit »

We're pretty sure you can't remove the PGTOP sentence, but we'll ask!

Please note we've only tested the GPS module keep fix up to 25 Km altitude - if you need it to go higher than that, it may not keep the fix!

spoz
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by spoz »

I assumed from the product description that with this firmware the 18km limit is applied only when the velocity also exceeds 500m/s. On that basis I think there should not be any higher limit above 25km programmed in unless you have reason to think otherwise? I realise that GPS devices don't have a lot of testing at those altitudes and it may lose a fix for other reasons.

If you could find out about the PGTOP sentence that would be helpful; I can obviously work around it if I have to but inthe interests of code speed and reliability I'd really like just the bare minimum sentence output.

spoz
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by spoz »

Any updates on this?

JD3
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by JD3 »

How about installing an antenna?

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adafruit_support_bill
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by adafruit_support_bill »

The manufacturer tells us that all altitude limiting has been removed. So far, the highest reported readings we have had in actual use are from about 25,000 feet.
http://forums.adafruit.com/viewtopic.ph ... 6&p=145726

spoz
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by spoz »

I don't mean to sound arrogant but I know the altitude limit has been removed because it says so on your product page.

What I'm asking about is whether there is a command I can send to remove the PGTOP sentence from the output.

The reason I'm asking is because the MTK3329 didn't have PGTOP but the MTK3339 - which you market as an upgrade - does have PGTOP. Your product page didn't tell me that and now I have to code around it. It's trivial I know but I already stated why I want to remove it if it's possible.

I would still very much appreciate any straight answer I can get.

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adafruit_support_bill
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by adafruit_support_bill »

There were two topics mentioned in the post immediately preceding the "Any updates on this?" post. I gave you a straight answer to the one I had an answer for. I am checking into the other.

adafruit
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by adafruit »

We got a response from GTOP - there is no way to remove the PGTOP sentence - it is a permanent addition to the firmware and there is no way for us to change the firmware as they are burned in at the factory.

For altitude, we have logs of it in a balloon keeping fix up to about 27Km after which it lost fix.

spoz
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by spoz »

Thank you for looking into it for me.

Tranc3r
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by Tranc3r »

Ahh..... I've come across this post and I fixed it myself, sad to see it was not helped at the time.

The original poster wanted to ask to stop the $PGTOP sentence from the showing up at the output, initially it was off from a brand new unit in factory settings.
After it ran the "parsing" example or whatever example from Adafruit_GPS library, it turned it on as part of the code was to turn it on (default -_-).

To turn it on/off, use the following:

#define PGCMD_ANTENNA "$PGCMD,33,1*6C" // request for updates on antenna status
#define PGCMD_NOANTENNA "$PGCMD,33,0*6D"
GPS.sendCommand(PGCMD_ANTENNA); // ON
GPS.sendCommand(PGCMD_NOANTENNA); // OFF

or just use Serial.println if using hardware serial.

Serial.write("$PGCMD,33,0*6D\r\n");
Serial.println("$PGCMD,33,0*6D");

Check the checksum number here: http://www.hhhh.org/wiml/proj/nmeaxor.html
that is marked by * and then a number, is checksum.


note: use this for getting checksum calculation: http://www.hhhh.org/wiml/proj/nmeaxor.html

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Mastericeman
 
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Re: Ultimate GPS MTK3339 Remove $PGTOP sentence

Post by Mastericeman »

Nicely done, very helpful.

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