Adafruit Ultimate GPS logger shield not outputting antenna s

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aidanmontare
 
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Adafruit Ultimate GPS logger shield not outputting antenna s

Post by aidanmontare »

Hi! Apologies for posting on what seems to have been discussed elsewhere in the forum, I haven't found guidance that works in my situation.

I recently purchased and have been having a lot of fun with the Adafruit Ultimate GPS Logger Shield for the Arduino. I'm primarily using it for the PPS output as part of some timing applications, which works, but I also verified that I get most of the NEMA sentence outputs using some of the example scripts.

However, I don't get any of the $PGTOP antenna status messages, even after I've sent the serial command to enable these ("$PGCMD,33,1*6C") as a part of my Arduino sketch's setup() routine. I think I've done everything described in the Adafruit guide [1], and I've tried using both direct serial and software serial. I also tried sending the serial command via the command line as discussed in [2], but no luck.

As I said, otherwise, the module appears to be working. Any thoughts?


[1] https://learn.adafruit.com/adafruit-ult ... s-579013-3
[2] viewtopic.php?f=19&t=57381&p=744746

p.s. For context, I'm mostly interested in the antenna status messages because my external antenna, which initially seemed to work, no longer does, and I'd like to know if the GPS module can even see a connection. It would also be useful to incorporate an antenna status message into my project's user interface, though, so I'd definitely appreciate being able to receive these sentences.

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mikeysklar
 
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Re: Adafruit Ultimate GPS logger shield not outputting anten

Post by mikeysklar »

Our MTK3339 (PA6H) Ultimate GPS models support PGTOP and running the 5632 firmware or higher.
8/4/2014: firmware version 5632 - back compatible but apparently adds better high-altitude calculations according to GTop
https://www.adafruit.com/product/790

The Ultimate GPS logger shield you are using is based on the MTK3333. Which firmware are you running on it?

I suppose we could do some signal strength testing with the antenna on versus off and see how many satellites you pickup and how long it takes.

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aidanmontare
 
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Re: Adafruit Ultimate GPS logger shield not outputting anten

Post by aidanmontare »

Thanks for your reply! Your response prompted me to look at what specific module was on my board, and I realized I was looking at instructions for the MTK3339-based modules, not the MTK3333-based ones.

My module is a CD PA1616D, which as you said uses the MTK3333 chip. I found the datasheet for this module here:

https://www.adafruit.com/product/5186

As it says on that page, "The commands for querying the antenna have changed slightly so existing projects may need to update their firmware." I used the commands in the new datasheet, and now things are working! My serial monitor is happily receiving antenna status messages (which on this module begin with $PCD not PGTOP).

Now that I'm aware of this, I realized that the product page for the logger shield does make mention of this in the revision history: https://www.adafruit.com/product/1272

It might be helpful if the product tutorial (https://learn.adafruit.com/adafruit-ult ... ger-shield) made mention of the difference and provided a link to the new datasheet. But now that I'm aware of the difference, it was pretty easy to substitute the new commands for the old ones.

Things are now working well! Of course, I've still got to fix my external antenna, but that's a separate problem. At least I've got messages to inform me when its working!


In case this is useful for anyone else: I also think the Adafruit GPS library only supports the commands for the PA6H module, not the PA1616D module (based on the commands that are defined in the library https://github.com/adafruit/Adafruit_GP ... uit_PMTK.h). I just defined the commands for my module within my Arduino script.

Also, the meaning of the return value is different between the PA6H and PA1616D modules! Make sure you're reading the correct datasheet!

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mikeysklar
 
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Re: Adafruit Ultimate GPS logger shield not outputting anten

Post by mikeysklar »

@aidanmontare,

Thank you for the datasheet pointer and command change suggestions.

Please start a new thread if you need any assistance with the antenna working.

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aidanmontare
 
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Re: Adafruit Ultimate GPS logger shield not outputting anten

Post by aidanmontare »

The antenna problem turned out to be the u.FL to SMA pigtail I was using, which had a short. Thankfully, I was able to fix it!

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mikeysklar
 
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Re: Adafruit Ultimate GPS logger shield not outputting anten

Post by mikeysklar »

Awesome. You are all set!

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