AssetTrackerRK with external Antenna

On my assetTracker V2 board I’m using the library from AssetTrackerRK - and i’m trying to improve the speed of the GPS process.

I’m currently using the tinyGPS++ library along with a coin cell battery and an external GPS antenna… ( not sure how good this once is )

The coin cell has helped a little - but i can wake my device up and it may get a GPS lock, then after waiting a few minutes i knock it to wake it up and it no longer gets a GPS. Besides soldering the battary holder do i need to enable this additional battery within the code somewhere?

I’ve read there is process to toggle between the internal and external antenna - but without including the AssetTrackerRK library how would i go about this OR indeed do i need to?

Also i’m guessing the external antenna’s are not all equal. Can any one recommend a small external antenna which gives good results and is small enough to fit with the tracker inside the box which comes with the unit.

Sorry - i know thats a lot of questions - but i’m trying to test everthing and i keep taking steps backwards as its not as reliable as i hoped it would be.

If you want to set the external antenna without using the AssetTrackerRK library, just copy the code out of it and paste it into your code:

There’s no software configuration for using the coin cell battery on the AssetTracker V2 but make sure you cut the jumper trace so the super capacitor is disconnected. The only thing the coin cell does is maintain the GPS state (almanac and ephemeris data) when the power is removed for more than a few minutes. This allows a fix to be obtained faster and with fewer satellites visible. However, it doesn’t provide any benefits if you normally leave the GPS powered on.

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I’m turning the GPS off to save power which is why i have coin cell battery. ( my unit can bee of anything between 2 minutes to 4 hours depending upon movement waking it up )

I’ve cut the jumper and soldered the center / CC to together - so i’ll test these.

I have 2 units - one with an external antenna so i have added the code to that to force it to use the external antenna.

thank you for the quick reply

If you are using an Electron and keep the LiPo connected, there is no need for a coin cell, since the LiPo will keep the onboard super cap powered. And even if you disconnect the LiPo for a few minutes (as Rick already mentioned) the super cap will bridge the gap.

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But does the supercap only hold the info for a short period of time?
I need a solution which will hold the GPS data for several hours. with GPS off to save power.

I thought that powering down the GPS for several hours would mean i would cause the GPS to do a COLD start which would take quite a bit of time. (something i want to try and avoid if possible )

Occasionally my devices will go into DEEP SLEEP for 24 hours ( not using the WKP to wake them ) and i was hoping the coin cell would aid in speeding up the GPS location when it woken up again.

My main goal is to make the GPS process as fast as possible - but also to make the battery last as long as possible. If i kept the GPS ON i know its nice and quick, but it drains my battery too quickly.

My initial quick testing GPS positioning is quicker when the device is woken by movement… yet to test for several hours sleeping.

Have you read this part of my post

Sleep mode does not depower the 3v3 regulator and hence the GPS SRAM will stay powered as long the LiPo provides power.

Yes - but i have read so many posts that I’ve gone a little bit hazy… I’m battling against a steep learning curve and forum posts from months / years ago ( which are possibly for the old version ) and sadly bouncing around several projects!

So beside the coin cell powering GPS SRAM when the LIPO is removed - are there any other benefits to having the coin cell on the board?



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Sorry, I didn’t explain that very well. As ScruffR pointed out, the supercap is charged by 3V3, and thus the GPS data is saved as long as you’re supplying power by VIN or the LiPo battery, even if you’ve powered down the GPS. 3V3 is also powered if the Electron is in sleep mode.


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Thanks @rickkas7 and @ScruffR.

@rickkas7 - by default with the tinygps++ library from your version of the asset tracker software. does it use the internal antenna by default?

The documentation for the M8 is vague on how persistent the UBX-CFG setting really is, so I would just specify the external antenna in setup().

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