Today, there are dozens of off-the-shelf solutions for a GPS tracking device. Most of them use GSM, some of them use satellites, and all of them are astonishingly inexpensive. If you want to track a car, dog, or your luggage, you’ve never had more options.
[Emilio] wanted to track his own car, and the original solution for this was a smartphone. This smartphone was also a good choice, as it’s a programmable GPS device connected to a cell network, but there had to be a simpler solution. It came in the form of an eight euro GPS module and a three euro GSM module (Google Translatrix right here). The rest of the hardware is an ATMega48V [Emilio] had sitting around and a 2500 mAh lithium cell. It’s a cellular tracker make out of eleven euro’s worth of hardware and some junk in a drawer.
There are only a few caveats to this hardware. First, the ATmega48V only has one UART. This is connected to the GPS module at 9600, 8N1. The connection to the GSM M-590 module is only 2400 bps, and slow enough for a bitbanged UART. This hardware is soldered to a piece of perfboard, thus ending the hardware part of this build.
The software is a little more complex, but not by very much. The GPS part of the firmware records the current latitude and longitude. If the GSM module receives a call, it replies with an SMS of the current GPS coordinates and a few GPS coordinates seen earlier. Of course, a pre-paid SIM is required for this build, but those are cheap enough.
Not even ten years ago, a simple, DIY GPS tracker would have cost a small fortune. Now that we have cheap GPS modules, GSM modules, and more magical electronics from the East, builds like this are easy and cheap. What a magical time to be alive.