Documentation · New device

Documentation · Original device

Firmware updates.

The DiscoX is designed to be easy to update. This page walks you through entering Firmware Update Mode and dropping a new .uf2 file onto the device.

On this page

Latest firmware01 Entering update mode02 Flashing the .uf203 Troubleshooting04 Changelog05
01 · Current release

Latest firmware

The DiscoX runs an open-source C++ firmware built on the SAP6 platform. Keep an eye on this page for bug fixes, calibration improvements and new features.

Showing the new device — the one with the large orange trigger button.

Showing the original device — four identical blue buttons, no orange trigger.

Download mrzappy-v2.0.1.uf2 All releases on GitHub

v2.0.1 · released 2026-09-15 · sha256 3d4f…d200

Download discox-v0.1.0.uf2 All releases on GitHub

v0.1.0 · released 2026-06-19 · sha256 4c5c…23e0a

02 · Bootloader

Entering Firmware Update Mode

Firmware Update Mode (also called UF2 bootloader mode) is what makes the DiscoX appear on your computer as a USB drive named DISCOX. To activate this mode enter the device menu, select "Update Firmware" and confirm yes. You'll then be able to plug your device into a PC and it'll pop up as a USB drive.

● Bootloader

The device looks like a USB drive

When the DiscoX is in Firmware Update Mode, the screen shows a steady bootloader prompt and your computer mounts a removable drive called DISCOX.

Method A — From the menu (recommended)

If your DiscoX is already running working firmware, this is the easiest path. No buttons gymnastics required.

  1. Power the device on and wait for the home screen.
  2. Press Button 3 to open the menu.
  3. Scroll to Update / Settings and select with Button 3.
  4. Select Update Firmware.
  5. The device reboots and the screen shows the bootloader prompt.
  6. Plug in USB-C — a drive named DISCOX will appear on your computer.

Method B — Double-press reset (recovery)

Use this if the firmware is unresponsive, the menu won't open, or a previous flash was interrupted. The device's reset is reachable through the USB-C port without opening the case.

  1. Connect the DiscoX to your computer with a USB-C data cable.
  2. Quickly double-press the reset button on the mainboard (or, on assembled units, double-tap Button 4 within 0.5s while plugged in).
  3. The status LED settles to a steady amber/red glow — that's the bootloader signal.
  4. The screen shows DISCOX BOOTLOADER and the DISCOX drive mounts.
Tip · Use a data cable

A surprising number of USB-C cables are charge-only. If the device powers on but no drive appears, swap the cable before assuming anything is wrong.

How to tell you're in update mode

  • The screen shows DISCOX BOOTLOADER with a version line.
  • The status LED holds a steady colour (no breathing or pulsing).
  • A removable drive called DISCOX has mounted on your computer.
  • The laser is off and buttons no longer take readings.
03 · Drag & drop

Flashing the .uf2

With the device in Firmware Update Mode and the DISCOX drive mounted, you're ready to flash.

  1. Download the latest .uf2 file from the link above.
  2. Open the DISCOX drive in Finder, Explorer, or your file manager.
  3. Drag the .uf2 onto the drive (or copy & paste — either works).
  4. The drive will dismount on its own as flashing starts. Don't unplug.
  5. After 5–15 seconds the device reboots into normal firmware and the home screen returns.
  6. Open Menu → About to confirm the version number matches what you flashed.
Don't interrupt the flash

Once the drive disappears, the chip is rewriting its own firmware. Pulling the cable mid-flash can leave the device in a half-written state — recoverable via Method B above, but easier just to wait the few seconds it takes.

04 · If something's off

Troubleshooting

No drive

The DISCOX drive doesn't appear

Try a different USB-C cable — many are charge-only. If you're sure the cable is fine, use Method B (double-press reset) to force the bootloader.

Stuck

Device won't boot after flashing

Hold the power button for 10 seconds to fully power down, then plug back in and re-enter update mode via Method B. Re-flash the latest known-good .uf2.

Wrong file

Drive ejects with a FAIL.TXT

The bootloader rejected the file. Make sure you downloaded the .uf2 for DiscoX (not a generic SAP6 build) and that the file isn't corrupted — re-download and try again.

Settings

My config.json was wiped

Major firmware updates can reset the settings file to defaults. Your calibration is preserved separately. Re-edit config.json via Menu → Update / Settings → Edit Settings File.

05 · What's new

Changelog

v2.0.1 — 2026-09-15

  • First public release for the new device, built on the single-processor board.
  • Survey legs are held on the device until your phone confirms it has them — pull the device out of range mid-trip and nothing is lost.
  • The firmware version is now shown on the boot splash, so you can check what a device is running without opening it up.
  • Laser shots that can't be trusted are rejected rather than recorded, and error messages say what actually went wrong.
  • The laser now switches off with DOWN while idling, saving battery between legs.
  • Calibration: undo a recorded point with DOWN, save with UP+DOWN, and a dry-run test before committing.
  • Settings, calibration and unsent readings are editable over USB as a plain drive (Menu → Settings → USB Drive Mode).
  • Disco mode, with the Mario theme hidden in it.
  • Numerous storage-reliability fixes around calibration saves and reflashing.

v0.1.0 — 2026-06-19

  • Initial public release of the DiscoX firmware.
  • Main board and BLE board UF2 builds published via automated GitHub releases.