Barista

Barista lets a Wii U GamePad act as a wireless second screen, controller, and audio device for a desktop application. It owns pairing, the dedicated Wi-Fi access point, low-latency media delivery, GamePad input, and a Qt 6 desktop application. It is not affiliated with Nintendo.

What it does

• Pair and reconnect a real Wii U GamePad from the desktop app.
• Show Barista's logo while no application is streaming.
• Run in Screen + controller mode: an application sends video/audio to the GamePad and receives its input.
• Run in Controller-only mode: expose standard buttons, sticks, triggers, and D-pad through Linux uinput.
• Keep the privileged radio/service work behind a D-Bus + polkit boundary; the Qt application runs as the regular desktop user.

The application connector is AppHook, internally nicknamed MUG (Media User Gateway). It is a Linux-local Unix SOCK_SEQPACKET protocol, not an emulator-specific integration. It carries RGB video, stereo PCM, and GamePad input reports. Other applications can implement AppHook instead of embedding any radio or pairing logic.

Projects that work with Barista

These are experimental forks, not features of or endorsements by their upstream projects.

• BetaZay/Cemu, branch barista-connector-prototype — Wii U GamePad video, audio, controls, and touchscreen integration.
• BetaZay/Azahar — 3DS top/bottom-screen layouts, video, audio, controls, touchscreen, motion, and C-stick support.

The prototypes use Barista's default per-user session socket, /run/barista/media-<uid>.sock, automatically. Other clients can use that endpoint directly or set BARISTA_MUG_SOCKET as a development override.

Wi-Fi requirements

The GamePad uses a dedicated 5 GHz access point. Barista needs a Linux Wi-Fi adapter and driver that can create a 5 GHz AP using nl80211/hostapd, remain stable at the selected channel, and support the GamePad's required association and encryption behavior. This is not ordinary home Wi-Fi: starting a session temporarily takes over the selected adapter from NetworkManager.

Use wired Ethernet or a second Wi-Fi adapter if the machine needs Internet access while Barista is active. Keep the GamePad close to the adapter while testing; radio conditions still directly affect video quality and latency.

Development and physical GamePad streaming were tested with the Realtek RTL8852BE (rtw89_8852be) on Linux. That proves this adapter/driver can work; it is not a guarantee for every firmware, kernel, access-point channel, or adapter. macOS and Windows currently provide the portable UI/core only—the real GamePad radio backend is Linux-only.

The TP-Link Nano AC600 USB adapter (rtw_8821au) is also a recommended tested option. It can take several seconds to leave managed Wi-Fi mode and bring up the pairing access point; wait for Barista to report that pairing is ready before using SYNC. It was stable once the pairing AP was running in our testing.

For additional confirmed and incompatible hardware reports, see Vanilla Wii U's Wireless Compatibility wiki.

Use

Install Barista, then open it normally from the desktop launcher. The system service is activated on demand; use Start to authorize the Wi-Fi takeover. Use Pair GamePad only when pairing is needed. Closing the window keeps it in the tray by default.

The Advanced page displays the automatically managed AppHook endpoint. Clients should use that default endpoint; the environment variable is only an optional development override:

your-app

The endpoint exists only while a Screen + controller session is active. It is owned and permissioned for the desktop user; applications must not run as root.

Build and install

See COMPILING.md for dependencies, a development build, tests, and system installation.

Developers integrating an application, control client, or future backend should start with the API documentation.

Status

Barista is active development software. The primary Linux pairing, streaming, and AppHook paths have been exercised with real hardware, but adapter/driver compatibility and media recovery still need broader hardware testing.

What's working

• Pairing
• Basic A/V streaming
• Inputs from buttons and sticks
• AppHook for third-party apps

Needs work

• Video still has artifacts and can get behind and stutter.
• Audio occasionally stutters.
• The GamePad still requests recovery much more often than it does with a real Wii U connection.
• Touch needs broader application and calibration testing.
• Gyro needs broader application and orientation testing.

Not started

• Camera
• Microphone
• NFC