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Consider adding GPS "Sensor"?

I wonder if the idea of adding GPS capability to the outdoor “Station” kit has been considered ? It would add precision to the sensor location and provide altitude data as well as accurate time.
Its a useful addition because:
UTC time would add quality factor to data values collected, not relying upon internal RTC which can drift, even when calibrated.
Altitude can be used to “correct”/adjust/normalise barometric pressure readings to mean sea level values (and this would then match up with Weather Bureau data).

HI @bryn.parrott

Thanks for joining the forum so actively!

Yes, we are currently working on integrating a GPS as a big customer request it for a project. We’ll release the documentation after so anyone can add it to his Kit.

We’re testing this module:

It works as an accessory and connects to the Kit via the AUX port

We’ll post here future updates

OK Thanks, I am looking at the SparkFun documentation now. I have some questions arising. Its OK if you are unable to answer all of them, I understand you are in development…

  1. Connection of the device to the SmartCitizen MCU. Can I assume you are using Qiic to Grove conversion cable and also Grove I2C hub: (?)
  2. The Dead Reckoning element of the NEO-M8U requires correct X,Y,Z axis orientation (North, East and vertical) to correctly perform its role; which has a home when the device is mounted in a mobile scenario such as Motor Vehicle. When the SmartCitizen is mounted on the side of a building outdoors, or flat on a desk or a shelf inside a building that may be an issue, different orientation is natural for each scenario. The orientation also depends on what Case Enclosure is used. How are you considering handling of these different situations?
  3. GPS antenna. By default, the Sparkfun GPS board comes without an antenna, it is purchased separately due to differing user requirements. There is a range of stick on Molex brand antennii with different cable lengths 50mm - 200mm, plus a magnetic mount antenna with a longer cable, also requiring an coaxial adapter cable.
    I think perhaps one of the stick-on antennas (~150mm) would suit me, (stick it on the outside of the case enclosure lid). Its probably a bad idea to set up a situation where the antenna needs to be plugged/unplugged often, because the little connector on the circuit board is fragile.
    Have you any thoughts on antenna selection to guide me ?
    4/. Adafruit make an arduino library available (naturally), I assume that you will use it and have the ATA processor read the position and altitude data, but a question arises in how to send this data through to the other processor. Maybe the API needs to be updated. Maybe firmware needs an update too (to allow the board to be configured into the system). Please can you indicate where you have identified (even if not yet executed) software/firmware changes that are likely needed to fully integrate this device into the SmartCitizen ecosystem. Have you got so far as to have a beta version ready for testing ?

Many Thanks…

OK, I ordered the Sparkfun GPS Module along with a Qiic to Grove adaptor Cable.
I am eagerly awaiting your documentation to see how this can be integrated into the Smart Citizen Kit 2.1.
I have ordered the Grove 6 way I2C multiway ataptor, because I’ll be using at least 2 I2C ports, including 128x128 OLED display and the GPS module.
I am assuming that I will somehow be able to jam the extra boards into my exterior case enclosure that is on order. ;:stuck_out_tongue_winking_eye::stuck_out_tongue_winking_eye:

Hi bryn,

The GPS integration development, is behind schedule because shippings are taking longer than normal.
We Still don’t have this module available to do tests, so most of your questions are still to be answered :wink:

Connection can be done with an adapter cable.
There is an interesting reading about antennas here.

About the code, we try to use open source libraries when available, sometimes we need to fork them and do some modifications, we are still not sure if that’s needed in this case.
The firmware of the SAMD21 chip on the SCK will need to be updated, specifically the part on Auxiliary sensors that takes care of detecting external sensors on boot and enabling them. The update is very simple you can check how to do it in this guide.

As soon as we have a working branch I will post it so you can play with it!

OK, well my Sparkfun GPS board should be here tomorrow and the main smart citizen kit in 5 -7 days. (It turns out USA is closer by UPS to Australia than China is via FedEx … Who knew ? ) So maybe I can do some tests for you. I am happy to help out that way. :slight_smile:
Sparkfun have embargoed their GPS Antennas but I got some from Digi-key. The ones I ordered are the passive Molex flexible type. I happen to also have a ceramic type on hand left over from a Linkit One board. If I cannot pick up satellites with either then I will have to get one with inbuilt LNA I guess.

GPS Postage stamp arrived from Sparkfun, and flexible molex antenna(s) from Digi-Key.
I hooked them up to a Seeeduino board for a quick test. I ran the example sketches provided by Sparkfun.
I put all of them onto my north facing window sill. Found that I can quickly pick up 15 or more Satellites. Position readings are OK, but altitude reading varies up and down by + 5 - 10 metres.
Time of day from the inbuilt RTC is of course GMT/UTC but that is to be expected. This could be used to automatically set the RTC on the main kit board. It should be possible to calculate actual local time using a lookup table, but its not simple due to the large number of time zones and the latitude dividing lines between them are often not straight. There might be a local time calculation engine in library form out there somewhere. It would be better and easier for the user to set a configuration item for Time Zone Offset.

If altitude from GPS were to be used to normalise pressure readings (to calculate mean sea level) from the kit sensors then it might be a lttle inaccurate. I already know that my altitude is 96.0 Metres above mean sea level. But the GPS tells me its as much as 118 M