Beginner tries to build GPS tracker :-)

#1

Hi all,

Short version: do you know about projects with the Heltec GPS Tracker? Do you have own / know about Blogs, Youtubes etc. you could recommend for a beginner? (German preferred :slight_smile: )

Long version:

I’ve been a passionate software developer all my life, but I’m completely new to Arduino & Co.

Currently I’m trying to solve the following problem: I would like to track all tours I’m doing with my camper van. Just to have those recordings, perhaps to geotag some photos afterwards or just to see where I’ve been to. Live uploading of tracking data IS NOT my main focus.

I could simply do this with my phone (like I’m already doing it on hiking tours), but when driving, I too often forget to activate recording. Therefore I’m looking for an automated solution.

I’m not fixed in my decision if I buy a ready device, use an app which kind of automates this on my phone or build a device on my own, whichever is more interesting, simpler or whatever. It’s a hobby, so the most interesting solution will probably win and not the cheapest, easiest or best solution.

According to this, I recently bought this “GPS tracker” device which I’m not sure about if it is Heltec or Seamuing or whatever since someone used a Heltec package and put a Seamuing sticker across the Heltec line.

I successfully uploaded the provided test code onto the device. GPS works, display works, WLAN works, tried several examples, very promising.

The idea I’ve got in mind is that this tracker should collect GPS data whenever it is powered by car’s power, and it should upload it whenever it is connected to a known WLAN (the camper is, when unused, parked in perfect range of my home’s WiFI, so this would be the perfect option).

So the questions I have in mind are for example:

  • does the module have any non volatile memory where I can collect the data while not in WiFi range? Or will I have to add a SD card reader?

  • the device shall be mainly powered by the car, but as I said uploading will probably happen when the car is parked, so I will need kind of buffer which lasts at least some minutes. What kind of battery can I connect (I did not find any documentation about this) and can I distinguish if it is externally powered or by battery?

  • how do you deal with cases for your projects? Do you all own a 3D printer (I don’t) or are there solutions getting around without this? I found some standard cases to buy, but if I, for example, need to add a SD card shield, I think this probably won’t work with standard cases

  • how could I power the device by car? Do I need a 12V-USB-adapter, or is there an even simpler solution to directly power it by the car’s power?

This post doesn’t only aim for answering this concrete questions. I’m mainly seeking for inspiration, other projects you know about etc.

Any reply is appreciated! Thank you very much in advance for your patience.

Marcus.

#2

Ow… a well-formatted, well-formulated, constructive post on the forum? Why are my eyes bleeding? Ah, tears of joy!

So… as a product of mine features the Tracker with most of those options checked, here’s some advice:

  1. Get yourself an accelerometer - you can use this for motion detection. If the car starts moving, it’s got to wake up. (Usually, this can be triggered by an “any motion” interrupt, although names maybe vary for different products.)
  1. Your device has 8MB of flash. This is where you upload your code to - usually taking up to 1MB or 2MB of flash. If you live fancy and have an OTA partition for OTA updates, this means that you have 4MB or 6MB of flash left for other files (look up “partition tables”). The downside of this flash is that you need to do somewhat fancy stuff to get it off of your device - a WiFi webserver commonly does this trick as it allows you to connect to your device and download its files. It requires a couple extra steps compared to an SD card maybe, but it works.
  1. 3.7V Lithium batteries such as 18650 if you like round shapes (hmmm…) or those flat LiPo battery packs.
  1. There is code that can detect if the USB-port is connected to a USB-host (such as a laptop or PC). Otherwise you will have to add e.g. a voltage divider from the 5V pin (active iff (if and only if) USB is connected to anything at all), to some input pin that you can read to see if there is power.
  1. eBay has some cases for the Wireless Tracker, or if you want to have fun learning 3D design and don’t mind paying for the filament required to print them and for shipping, we can work something out with my 3D printer from the Netherlands. I’ve got plenty of Trackers as you might imagine, maybe don’t have specific accessories but I can do test fits for your designs.
  1. That could work, or you can buy a 12V-5V step-down regulator and connect that to the 5V pin of your Tracker.

Good luck & viel Spass

#3

Anyone who is anyone has at least 2 3D printers and a laser cutter these days :wink:

For those with less time on their hands, even though I have the above, I just buy a plastic case and attack it with a Dremel - other makes of hand power tools are available. If you are using WiFi to upload data then you don’t really need to open the case, so you may not even need a power tool. For some projects I just use a takeaway tub that’s suffered some decoupage to make it look nice.


The most important thing is to get something working and then refine - if you get bogged down with planning then your workshop will look like mine, lots of part finished stuff.

1 Like
#4

Oh, sorry if I didn’t familiarize myself sufficiently with the customs of this forum :wink: I’ll try to improve.

Thank you for your kind reply!

I’m still thinking about connecting a SD card shield, but looking at the pinout, most of the pins seem already be connected to onboard stuff (LoRa, GPS, Display). Do you know how it would be connected? (Sorry if this is a dumb question, but remember I’m total beginner.)

Marcus.

#5

I was actually joking because it was a very good post for first time chatter :slight_smile:

The cool thing about SPI (as SD-card readers use SPI), is that different SPI devices can all share a set of pins, as long as they don’t end up being used at the same time. So you can share the MOSI, MISO and SCK of the radio - it’s just the NSS or CS that must be unique. (It would be a very very bad idea to use the RADIO_NSS for the SD card.)

But, the Tracker has pins 4/5/6/7/15/16 completely available anyway, which should be enough for you.

#6

A German and a Dutchman walk in to a bar and speak English …

I’m not sure @BNS noticed the :wink: but it’s all good.

If you have an end-point aka a web server for the device to transfer it’s data to, then I’d stick with that for now - if you don’t, I’d start with the SD Card. The idea here is that setting up an end-point has many moving parts, whereas a CSV on an SD Card can be imported rather easily.