jc2mouse — Joy-Con 2 mouse + controller (bondless / no pairing)

jc2mouse is a Linux userspace tool that connects to Nintendo Switch 2 Joy-Con 2 controllers over BLE without pairing/bonding, enables the optical sensor stream, and exposes virtual input devices via uinput.

It supports:

• Single Joy-Con mode: mouse + compact gamepad mode
• Combined mode (Left + Right): one full virtual Xbox-style controller
• Mouse overlay in combined mode: press C on the Right Joy-Con to turn only the Right Joy-Con into a mouse while the Left Joy-Con continues as the left half of the gamepad

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Why “session mode” is required

Joy-Con 2 will disconnect if Linux/BlueZ tries to enforce normal pairing/security behavior for LE connections.

This repo uses a patched bluetoothd in a safe, reversible session mode:

• stop bluetooth.service
• start jc2-bluetooth.service (patched bluetoothd)
• run jc2mouse
• restore stock Bluetooth on exit

The session swap is controlled by a helper script installed as:

• /usr/local/sbin/jc2-session

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Features

Single Joy-Con mode

Right Joy-Con 2

• Mouse: optical motion -> REL_X/REL_Y
• Clicks: (default) R = left click, ZR = right click, R3 = middle click
• Scroll: stick Y deflection (smooth)
• Toggle mouse/gamepad: C

Left Joy-Con 2

• Mouse (optional): optical + clicks + stick scroll
• Toggle mouse/gamepad: hold L + ZL
• Gamepad mode uses an Xbox-style mapping (Steam/xpad compat handled)

Combined mode (Left + Right)

• One virtual Xbox-style uinput controller:
  • Left stick -> ABS_X/ABS_Y
  • Right stick -> ABS_RX/ABS_RY
  • D-pad -> BTN_DPAD_*
  • ABXY -> Xbox positions (South=A, East=B, West=X, North=Y)
  • LB/LT from Left, RB/RT from Right
  • Start/Select/Guide mapped sensibly
• Right mouse overlay in combined mode
  • Press C on the Right Joy-Con:
    • Right becomes mouse (optical + buttons + scroll)
    • Right half of the gamepad is suppressed
    • Left continues driving the left half of the combined controller
  • Press C again to return to full combined controller

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Repository layout (high level)

• src/jc2mouse/driver.py — BLE (BlueZ D-Bus) + optical + uinput logic
• src/jc2mouse/cli.py — CLI entrypoint + auto discovery + session integration
• scripts/build_bluez.sh — builds patched BlueZ bluetoothd into /opt/jc2mouse/bluez
• scripts/setup.sh — installs systemd unit + session helper
• scripts/jc2-session.sh — start/stop/status session mode
• systemd/jc2-bluetooth.service — systemd unit for patched bluetoothd

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Setup

1) Install the systemd unit + session helper

This installs:

• /etc/systemd/system/jc2-bluetooth.service
• /usr/local/sbin/jc2-session

Run:

sudo scripts/setup.sh

2) Build and install patched bluetoothd

Build script downloads BlueZ (default 5.72), applies patches, and installs into:

• /opt/jc2mouse/bluez

Run:

sudo scripts/build_bluez.sh

The jc2-bluetooth.service unit uses:

ExecStart=/opt/jc2mouse/bluez/libexec/bluetooth/bluetoothd -E -n -d

3) Python install (venv recommended)

From repo root:

python3 -m venv .venv
source .venv/bin/activate
pip install -U pip
pip install -e .

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Usage

Session mode

sudo jc2-session start
sudo jc2-session status
sudo jc2-session stop

Running with a venv + sudo

sudo usually won’t see your venv PATH. Use one of these patterns:

A) Explicit venv path

sudo -E .venv/bin/jc2mouse run --auto

B) Use which while the venv is activated

sudo -E "$(which jc2mouse)" run --auto

Single Joy-Con (auto)

sudo -E .venv/bin/jc2mouse run --auto

Filter by side:

sudo -E .venv/bin/jc2mouse run --auto --side left
sudo -E .venv/bin/jc2mouse run --auto --side right

Combined mode (full controller)

sudo -E .venv/bin/jc2mouse run --auto --combined

Tips:

• Hold PAIR on Left until it connects, then hold PAIR on Right.
• Some systems require a retry or two due to unpaired BLE timing.

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Troubleshooting

“Bluetooth LE connection was aborted locally” / le-connection-abort-by-local

Usually means the Joy-Con wasn’t connectable at the moment BlueZ attempted the connect.

Try:

1. Hold the PAIR button during the connection attempt.
2. Don’t press other buttons while connecting.
3. Retry the command; combined mode may need a retry for the second Joy-Con.

bluetooth.service is masked

If stock Bluetooth is masked, session restore may fail.

Fix:

sudo systemctl unmask bluetooth.service
sudo systemctl enable --now bluetooth.service

Service sanity checks

systemctl status jc2-bluetooth.service --no-pager
systemctl status bluetooth.service --no-pager

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Roadmap / QoL

• LED management (player LEDs / mode indicator)
• GUI frontend (mode notifications / smoother UX)
• IMU decode (gyro + accel) and DualShock/DualSense-style emulation mode
• Battery level reporting (investigate feasibility without bonding)
• Rumble
• Windows port + Android/Winlator Cmod integration

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License / Contributions

Open to contributions and issue reports. Please include logs and device info (distro, kernel, BlueZ version) when reporting bugs.