Aaron Christophel's Web Flasher Delivers an Easy Path to $2 Apple AirTag-Like FindMy Trackers

Engineer Aaron Christophel is looking to make it easier to build Apple FindMy-compatible location trackers on circa-$2 hardware — writing a web flasher to quickly put a firmware and your FindMy/OpenHaystack public key on a Telink TLSR8252 module.

"Finished the Cheapo FindMy/OpenHaystack project," Christophel writes on Mastodon. "A simple Webflasher flashes the firmware on the €2 [Telink] TLSR8252 SoC [System-on-Chip], including your FindMy Public Key."

Apple's FindMy platform allows owners of its devices, including its dedicated AirTag tracking dongles, to locate them on a map — relying on a network of other FindMy devices to listen out for their signals and relay their location. OpenHaystack is an open-source reimplementation of FindMy which does away with the need to buy official AirTag trackers — and Christophel's tool delivers an easier way to flash low-cost hardware to create an off-brand "AirTag."

The web flasher is designed for use with Telink low-cost TLSR8252, which when combined with a CR2032 battery holder and battery can be turned into a circa-$2 AirTag-alike using a UART serial connection. The "ATC_FindMy Flasher" runs in-browser, using the WebSerial protocol. All the user needs, aside from the target device and a suitable USB-to-TTL UART dongle, is the unique public key to be associated with the tracker.

The only small catch: Christophel's tool only automates the client-device side of the equation. "[OpenHaystack] is not straightforward to use," the engineer admits. "You need to use an Apple device, or a MacBook, to use it simple; on a [Microsoft] Windows machine you need to set up a server and so on."

The web flasher is available on Christophel's GitHub Pages, and requires a WebSerial-compatible browser; the description on his demonstration YouTube video includes the parts list for building your own target tracker tag.