Live GPS Telemetry Tracker

A few years ago, computer programmer and running aficionado Ivor Hewitt needed a simple GPS tracker for ultra-marathon races and personal adventure runs. After considering using something off the shelf, he wasn’t able to find a device that perfectly suited his needs, so he decided to build it himself!

While one might see this as a difficult task, compared to running for well over 20 miles, such a design should be relatively easy! Nonetheless, as documented here, this build still had its share of challenges.

The tracker uses a Nordic Semiconductor nRF52840 as its processing core, which interfaces with a Quectel BG96 module for GPS and cellular communication duties. The nRF52840 chip can also communicate via BLE and other protocols, enabling it to work wirelessly with other devices (including those compatible with ANT+).

The tracker outputs data over cellular via the BG96 module, which can then be displayed via a server as a webpage. It can also connect to a computer as a USB storage device, providing access to log data after the race/training is over. Finally, a small OLED is installed on the unit as a local on-device user interface.

Components are mounted on a 60x50mm four-layer board, which features an exposed JTAG port for easy modification, and an I2C/IO connector for expansion. An onboard temperature and humidity sensor allows for tracking of these stats, and a custom enclosure finishes of the build.

Although the firmware is still a work in progress, Hewitt spent a significant amount of time working with the code logic to deal with fault conditions. After all, the last thing you want to worry about when starting a race (or training) is whether or not your electronics are working correctly!