OpenSpan

Drive your iPad from your PC — keyboard, mouse, audio, and clipboard — over Bluetooth. Free, local, no cloud, no account.

OpenSpan turns a Windows PC into a Bluetooth peripheral for a nearby iPad. Shove your mouse off a screen edge (Universal Control / Input Director style) and your keyboard and mouse drive iPadOS directly — type in Messages, scroll Safari, switch apps. Cross back and you're on the PC again. On the same Bluetooth radio it also routes your PC audio to Bluetooth earbuds and keeps a two-way clipboard in sync between the two devices.

No paid software, no account, no telemetry. A small Windows app plus a headless Linux VM doing the one thing Windows won't: pretending to be a Bluetooth keyboard.

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Run it as administrator

If you run any application as administrator, you must run OpenSpan as administrator too.

Windows UIPI does not deliver low-level input hooks to a lower-privilege process while an elevated window has focus. OpenSpan's edge crossing is built on those hooks — so if, say, you keep an admin terminal open, the moment that window has focus the mouse simply stops crossing to the iPad. There is no error, no exception, nothing in any log, and SetWindowsHookEx still reports success. Re-installing the hook does not help. Only closing the elevated window (or restarting OpenSpan, which steals focus back) appears to "fix" it.

It looks exactly like a bug in OpenSpan. It isn't. Run OpenSpan elevated and it goes away. The app warns you at launch if it isn't elevated, and the status bar shows ⚠ NOT ADMIN.

Why a VM?

Windows deliberately blocks applications from publishing the Bluetooth HID (keyboard/mouse) service — the OS reserves it. Linux's BlueZ does not. So OpenSpan runs a headless Debian 12 VM that owns the PC's Bluetooth radio (via USB passthrough) and advertises as a BLE HID keyboard; a Windows app captures your real input and streams it in.

your keyboard / mouse
       │  (low-level Win32 hooks)
Windows: openspan_portal.py ── TCP :9955 ──▶  Debian VM: openspan_ble.py
                                                    │  BlueZ GATT (BLE HID)
                                                    ▼
                                                  iPad  (bonded BLE keyboard)

PC audio ─▶ VB-Cable ─▶ WASAPI loopback ── UDP :4010 ──▶ VM: PipeWire ─▶ A2DP ─▶ earbuds

The single radio time-shares both jobs (BLE HID to the iPad, A2DP audio to the earbuds). Keeping the BLE link's airtime modest is what lets the audio stay clean — see TECHNICAL_NOTES.md.

Features

• Keyboard + mouse bridge — cross a screen edge to control the iPad; a keymap remaps modifiers (Alt→Cmd, Ctrl+C→Cmd+C, …).
• Bluetooth audio routing — send Windows audio to BT earbuds through the same radio, with the normal Windows volume slider and an in-app L/R balance.
• Two-way clipboard — plain Ctrl+C / Ctrl+V keep both machines in sync (via Apple Shortcuts + a tiny token-guarded LAN relay). See CLIPBOARD_SETUP.md.
• Lean window + tray — the command console tucks away by default for a compact window; Send to Tray keeps the bridge (VM, audio, portal) running in the background.
• Fast pairing + auto-reconnect — one click frees the whole radio for a full-power broadcast so the iPad finds the keyboard quickly, auto-starts the bridge the moment it bonds, then brings the earbuds back on their own.
• Single-file build — packages to one OpenSpan.exe (see BUILD.md).

Hard-won facts (read before you "fix" something)

These cost real debugging; they are the difference between working and not:

1. BLE, not Classic. Classic (BR/EDR) HID emulation pairs with an iPad but the iPad never accepts the keystrokes. Apple only cooperates over BLE HID (HID-over-GATT / HOGP). OpenSpan is BLE.
2. xHCI (USB 3.0) passthrough, not EHCI/OHCI. The USB 1.1/2.0 controllers dropped the Intel radio under streaming load; xHCI enumerates it in ~8 s and holds. VBoxManage modifyvm OpenSpan --usbxhci on (needs the Extension Pack), plus usbcore.autosuspend=-1 and options btusb enable_autosuspend=0 so the radio never idle-suspends.
3. encrypt-read forces the bond. iOS will connect to a BLE keyboard and even subscribe without bonding, then silently ignore every keystroke. Marking the HID report characteristics encrypt-read forces iOS to bond, which activates the keyboard.
4. Dual mode + not discoverable. The adapter runs ControllerMode = dual (BR/EDR stays enabled — the audio needs it) with Discoverable = false, so the iPad sees one clean LE keyboard entry instead of a second, un-pairable Classic decoy. The LE connection interval is pinned to 15–30 ms (MinConnectionInterval = 12 / MaxConnectionInterval = 24): tighter starves the audio, looser makes the mouse laggy.

Layout

openspan/
├── win/                         # runs on Windows (stdlib Python + ctypes)
│   ├── openspan.py              # control app — start here
│   ├── openspan_portal.py       # edge-crossing keyboard/mouse router
│   ├── win_audio_send.py        # WASAPI loopback → UDP audio sender
│   ├── openspan_setup.py        # drag-to-arrange the iPad among your monitors
│   └── openspan_launcher.py     # role dispatch for the packaged exe
├── guest/                       # runs inside the Debian VM
│   ├── openspan_ble.py          # BLE HID GATT peripheral + :9955 command server
│   ├── udp_to_sink.py           # UDP audio → PipeWire A2DP bridge
│   ├── *.service                # systemd units (BLE daemon, audio stack, agent)
│   ├── bt-list.sh / bt-connect.sh / btready.sh / env.sh …   # runtime helpers
│   ├── system/                  # captured host config (main.conf, drop-ins, grub…)
│   └── rebuild/                 # audio-stack (PipeWire/WirePlumber) install set
├── build_exe.py                 # package into a single OpenSpan.exe
├── TECHNICAL_NOTES.md           # deep "what makes it work" reference
├── BUILD.md · CLIPBOARD_SETUP.md · CLIPBOARD_DESIGN.md
├── LICENSE                      # MIT
└── README.md

Running it (Windows side)

Launch OpenSpan.exe (build it with python build_exe.py) or OpenSpan.bat. From plain source: python win/openspan.py — note Windows' unsigned-app reputation gate may block a raw pythonw.exe; BUILD.md explains the packaged exe and the interpreter workaround. The control app starts/stops the bridge VM and the input portal, arranges the iPad among your monitors, and edits the keymap. In the portal, cross the arranged edge to control the iPad; Esc pressed 3× in a row is the panic bail — it always returns the mouse to the PC, even if the bridge is broken. (Ctrl+Alt+Q still works as a backup; Ctrl+Alt+I toggles manually.)

Setup

The Windows side is turnkey (pure standard-library Python; pycaw is an optional extra for the volume slider). The VM is built with the provided scripts — a few steps, all scripted:

1. Create the VM: powershell -ExecutionPolicy Bypass -File create-vm.ps1 -Iso <debian-12-netinst.iso> — stands it up with the right hardware: xHCI USB passthrough, the NAT forwards (2222→22, 9955→9955, UDP 4010→4010), and a USB filter for your Bluetooth radio.
2. Install Debian 12 into it (minimal — a sudo user + the SSH-server task).
3. Provision it: the app auto-generates its SSH key (id_openspan) on first launch; get its public half into the VM, then copy guest/ in and run sudo bash guest/provision.sh all — this installs the packages, the BLE-HID + audio stacks, every config and systemd unit — and reboot.

cold-test.ps1 automates the software half of steps 2–3 against a reachable VM and verifies it (verify-provision.sh). The Windows→VM provisioning path is verified on a fresh Debian clone; the Bluetooth radio + iPad pairing are the hardware step you confirm once. PROVISION_SPEC.md and TECHNICAL_NOTES.md document every piece.

iPad pairing: Bluetooth ▸ tap OpenSpan Keyboard ▸ accept the prompt. It auto-reconnects after that. (Settings ▸ General ▸ Keyboard ▸ Hardware Keyboard appears once bonded — a handy check.)

Roadmap

• Working & tested: BLE keyboard + mouse, edge crossing, keymap remaps, Bluetooth audio routing (volume + balance), two-way clipboard, fast pairing, collapsible console + tray, auto-reconnect, single-file exe.
• Reproducible VM: create-vm.ps1 builds the VM, guest/provision.sh turns a fresh Debian into the working bridge, and cold-test.ps1 provisions
  • verifies it — the software path is verified on a fresh clone.
• Known limits: BLE sends relative mouse motion, so the pointer can drift (a corner-park re-sync is planned); touch-made copies on the iPad don't auto-sync to the clipboard (use Ctrl+C).

License

MIT. No warranty, no data collection, nothing phones home.