Skip to content
VYRO VR Docs

DFU Mode

DFU stands for Device Firmware Update. It’s a special boot mode where the tracker only runs its UF2 bootloader, not normal firmware. While in DFU mode the tracker shows up on your PC as a small USB drive, and you update it by copying a .uf2 firmware file onto that drive — VYRO VR Preflight does that copy for you — including recovery from a botched flash.

You should not enter DFU mode by accident. If you did, follow the exit section below.

When you actually want DFU mode

  • You’re updating firmware — see Updating Firmware
  • A firmware update failed mid-way and the tracker won’t boot normally
  • You’re flashing a development firmware build

How to enter DFU mode

Press the button 4 or 5 times in quick succession. The tracker enters DFU mode and the LED changes to a slow fade/pulse.

Plug it in over USB-C (a data cable, not charge-only) and your OS will mount a small drive. Current IBIS 2.0 trackers show up as MOCHI; older builds use NICENANO or SLIMEVRTRK, and Styria trackers SLIMENRF. Nothing else is needed — no drivers, no programmer app. Preflight’s Update Firmware page lists the drive the moment it appears.

How to exit DFU mode (you didn’t mean to enter it)

Power-cycle the tracker:

  1. Unplug it from USB if it’s plugged in
  2. Hold the button until any LED activity stops
  3. Single-press to power on normally

The tracker boots into normal firmware. Crisis averted. If it keeps returning to the bootloader, the firmware image is damaged — re-flash it (below).

DFU mode does not erase your tracker

Entering DFU mode is non-destructive. Pairing, calibration, and stored config all survive. The only way to lose those is to actually flash a different firmware image — and even then, re-pairing is fast.

Recovering from a failed flash

If a firmware update failed and the tracker is stuck:

  1. Confirm it’s in DFU mode (slow fade LED, USB drive shows up when plugged into PC). If not, press the button 4–5 times.
  2. In Preflight’s Update Firmware page, pick the tracker board and Flash to (drive) — or copy the correct build for your board from the firmware releases onto the drive yourself.
  3. Wait for the drive to disappear, then power-cycle.
  4. Re-pair if needed: Pairing.

If the tracker isn’t appearing as a USB drive at all (no fade, no drive), check the cable first — many “dead” trackers are charge-only USB-C cables. Then try a different USB port. If it still won’t mount, reach out via support.

Receivers

The receiver has the same UF2 bootloader (the VYRO VR Receiver mounts as FOX-BOOT). Preflight’s Update receiver button handles the whole sequence; by hand, send dfu over the serial console and copy the receiver .uf2 onto the drive that appears. HolyIOT receivers have no drive and need Preflight’s bundled DFU tool. Details in Updating Firmware.