Ripping the VIVE Ultimate Tracker dongle firmware
The Ultimate Tracker does its positional tracking through a USB dongle that talks to the host, and the dongle runs an nRF52840. This project is my third-party offline reverse-engineering archive of that dongle firmware. The whole thing only touches dumped bytes: no real hardware, and no redistribution of any vendor firmware or drivers. It has nothing to do with HTC or VIVE; the names only refer to the subject of study, trademarks belong to their respective owners, and if you think something is off, file an issue and I’ll take it down.
The firmware is two images stitched together: img1 is the app, landing at 0x27000; img2 is the bootloader, landing at 0xEA000. For the reverse engineering I set up an evidence grading scheme, and every conclusion is tagged with a level: [P] confirmed, [I] behavior understood but naming missing, [U] unknown, [R] needs real hardware. No evidence means it honestly stays [U]; no wild guessing.
By the time I wrapped up, function annotation hit 999/999, and img1 source-level reconstruction reached 574/599, i.e. 95.8%; the remaining 35 peripheral/ABI items don’t line up with the official SDK naming, which is the ceiling for offline work. The reconstruction was reassembled into a standard C project you can make directly, with the Arm GNU Toolchain 14.2 toolchain. The ability to modify was verified too: the original round-trip is bit-identical, and the recovery gate passes 50/50.
The workflow is strung together with Python. verify_campaign.py runs the offline verification, recovery_preservation_check.py is the anti-brick gate, safe_modifiable_set.py marks out the objects that are safe to modify, and make_flash_image.py does the packaging. If you want to promote something to a flashable candidate, pass the gate first, otherwise don’t even think about it. But let me be blunt: functional equivalence is not the same as byte-identity with the factory image, and passing the gate is only a necessary condition, not a guarantee it won’t brick. HID identity, live metadata, app hash, and rollback simply can’t be turned off without real hardware, and this project has never touched real-hardware flashing from the start.
Pure offline static reverse engineering, taken to an honest boundary: everything checkable is checked, reproducible, and documented. Beyond that is real-hardware flashing, and the risk and authorization there are a whole different matter. Actively discontinued as of 2026-06-30. It’s a detailed blueprint, not a ready-made flashing package.