Building a DIY Bluetooth Tracking Tag Using an ESP32 Board: A Weekend Home Lab Experiment

For tech enthusiasts and home lab tinkerers looking for a quick and engaging weekend project, microcontrollers often provide an ideal canvas. Recently, one developer decided to dive back into the world of affordable hardware by turning a few spare ESP32 boards into a custom proximity tracking tag. Utilizing readily available components, open-source tools, and a bit of collaborative troubleshooting, the experiment offered a fascinating look at what low-power Bluetooth technology can achieve on a budget, even if it falls short of replacing commercial-grade ecosystem trackers.

Getting Started with ESP32 Project

Make sure you have the right hardware and software before you begin

Whenever you begin a maker-style hardware project, ensuring you have all the necessary components on hand is critical. While software and firmware are usually easy to download and access on demand, missing a specific chip or development board can stop a project dead in its tracks.

The developer behind this weekend experiment already had a collection of microcontrollers in their spare parts bin, specifically featuring several ESP32-C3 Supermini boards. For those without a stash of microcontrollers already lying around, these compact development boards can typically be purchased online for just a few dollars. Alongside the hardware, a dedicated mobile device—in this case, a de-bloated Motorola Moto G running Android—was prepared to act as the monitoring hub for the experiment.

Having seen various similar plans circulating across maker communities and online forums, the developer felt confident diving in. Armed with a USB cable and a computer, the ESP32 board was plugged in to begin the process of transforming a generic microcontroller into a functional tracking tag.

Getting the ESP32 Mini Board Ready

The first step to making a tag

Turning a bare microcontroller into a functional tracking tag requires specialized firmware. Fortunately, open-source Bluetooth Low Energy (BLE) beacon firmware is widely available for ESP32 boards, though developers must research which specific version matches their hardware architecture. This firmware can usually be installed via browser-based web flasher utilities or custom scripts. Because the ESP32-C3 features built-in low-power Bluetooth capabilities, it is fully equipped to mimic the signals emitted by commercial tracking beacons.

Preparing the board for flashing requires interacting with its physical hardware interface. The ESP32-C3 Supermini features a tiny, dedicated boot button labeled "BOOT." While the text is quite small and requires close attention, holding down this button while connecting the board to a computer forces it into hardware bootloader mode.

To ensure the host PC properly recognizes the device as a connected COM port, the developer also had to press the adjacent "RST" (reset) button while maintaining pressure on the boot button. While working with micro-boards is generally straightforward, the diminutive scale of the components and labels demands patience. With the hardware properly initialized and recognized by the computer, the project moved smoothly into the programming phase.

Programming the ESP32 Board and Getting the Right Software

A few simple steps are all it took to get the tracker ready

While there are alternative methods utilizing tools designed to interface with major tech ecosystems like Google’s Find My network, the developer opted to avoid those platforms entirely. Instead, they chose to write custom firmware using the Arduino IDE, which would then be compiled and flashed directly onto the ESP32 board, paired with a separate mobile monitoring application.

Initial documentation and guidance for setting up a Bluetooth Low-Energy beacon on the card were sourced directly from manufacturer resources provided by Espressif. Opening the Arduino IDE, the developer attempted to configure the necessary BLE libraries on the chip. However, this phase proved to be the most technically challenging part of the weekend experiment.

Engaged in ongoing home lab exploration, the developer reached out to a colleague for assistance in refining and debugging the custom script. Syntax errors were quickly identified and corrected, and the updated beacon script was reviewed for deployment. On the host Linux machine, an additional administrative step was required—adding the user profile to the local dialout group—to grant the necessary permissions for uploading scripts via the serial port. With the code successfully compiled and transferred to the board, the system was ready for real-world testing.

Tracking Things Down

Using a mobile app to track my Bluetooth tag

With the programming hurdles cleared, the monitoring phase of the project began. The developer downloaded nRF Connect on the Motorola smartphone to serve as the tracking interface. Unlike proprietary networks managed by Apple or Google, this setup does not offer global, wide-area geolocation tracking. Instead, the application monitors signal strength to indicate when the tag is within proximity or when it has moved out of range, making it a fittingly simple utility for an introductory hardware project.

Inside the nRF utility, the custom chip—affectionately named "Mauve Porpoise"—was easily detected. The developer tracked the received signal strength indicator (RSSI), measured in dBm, as the board was repositioned around the environment. When placed directly adjacent to the phone, the signal registered at -67 dBm. Interestingly, the signal strength temporarily increased as the board was moved to another room, a phenomenon easily explained by radio frequency signals bouncing off household walls and structural obstacles.

To test the physical limits of the hardware, the board was connected to a secondary Android phone to maintain continuous power and taken outdoors into the garage, yard, and driveway. An observer monitored the mobile application to see precisely when the connection dropped. Based on the walk test, the signal fell out of range when the board reached the opposite side of the yard, situated roughly 40 feet away from the home lab workspace.

This functional distance compares reasonably well with the standard operational range of commercial tracking tags. However, the fundamental limitation remains structural: unlike mainstream consumer trackers that leverage vast crowdsourced device networks to relay global location data, a standalone ESP32 beacon only signals whether an item is nearby or entirely missing. Consequently, the creation functions far more as an educational weekend learning exercise than a viable tool for long-term asset tracking.

Nevertheless, integrating miniature batteries or portable power packs could turn these boards into effective "left-behind" proximity alert tags for basic, localized use cases. Re-engaging with the world of microcontrollers proved to be an entertaining and rewarding weekend endeavor. While the development process was not entirely seamless, the resulting proximity tracker satisfied the maker’s curiosity and laid the groundwork for future embedded systems and home lab projects alongside ongoing Raspberry Pi experimentation.