TTNmapper on (BLE)steroids


Well, my initial plan when buying the t-beam with gps was to some day get it mounted on my car’s roof, probably still with it’s own battery, charging via usb every now and then.

But thinking about it further (nothing else to do while driving :roll_eyes:) - i realized that there could be another benefit from having an external gps(antenna): replacing my phone’s gps with it, like in the old days … remember ‘GPS mice’?.. i can’t help, but gps in car still sucks quite often after all these years.

And well, the ESP32 got BT/BLE, so hey - this can’t be that hard … can it? Turns out it isn’t as easy as i hoped, as there doesn’t seem to be any openly available code doing just that, but there’s a lot of information which should make it possible to piece it together relatively easy… i’m still in early stages of researching and testing, but thought i’d put my links together in here, and maybe someone would like to follow along and/or cooperate/contribute. For sure this would make it a bit of a different ttnmapper-app, and probably one could also add some other fancy stuff like configuring channel/SF from the phone.

so, what’s the goal:

  • the ttgo t-beam either in a housing on the car roof, or inside with an antenna like this
  • receiving gps and doing it’s lora/mapping-stuff as always
  • but at the same time acting as a BT/BLE-service for location
  • which one can connect one’s phone or other devices to

what i’ve found so far:

only tested the UART example included in the library so far, which lets me connect, but only sends rubbish (like wrong baud rate on serial port), didn’t debug yet.

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I’m having a permanent GPS tracker in the car. I use magnetic roof antennas for 868 MHz and an external active (!) GPS antenna.
The TTGO T-Beam has an U.fl plug for GPS, so it should support an external Antenna. (Note: the antennas I use are active and expect 3,3-5V power in order to work correctly; I doubt the TTGO does this).

This is what I’m using:

They work well, even at high speeds. The signal is incredibly better and more reliable than with just indoor antennas.

I’m unfortunately not an expert on the other items.



also on my workbench yet:
one of this kind of ‘shark fin’ antennas i planned to use as a housing. not tested yet if it really could withstand the elements, but probably the only reasonable solution for car’s like mine not having an antenna-hole in the roof to put the whole thing outside.

but i myself am actually starting to consider being less reasonable and drilling a hole… :sunglasses:


I did not find any frequency specification for the antenna… That’s a bit spooky.

What I did not mention: I mounted the active components in the boot (“Kofferraum”), I also find 12V there (converted to 5V using a car charger for mobile phones), and then run the antenna cables to the outside (“in die Gummiisolierung eingeklemmt”). No problems with that for the last 2 years.
And no need to harm the car by drilling holes.