8BitDo Ultimate 2C Wireless Controller Visualizer

This project is a lightweight, browser-based tool designed to visualize the input state of the 8BitDo Ultimate 2C Wireless Controller.

It was developed primarily to reverse-engineer and document the specific control mappings (buttons and axes) of this controller for use in an embedded robotics project. By visually confirming which physical inputs correspond to which logical Gamepad API indices, we established a reliable mapping table for the hardware.

How It Works

The application uses standard web technologies and requires no external libraries or frameworks:

• HTML5 & SVG: The controller is drawn programmatically using Scalable Vector Graphics (SVG). This allows for easy manipulation of individual parts (changing colors, moving joysticks) without needing external image assets.
• CSS3: Handles the visual styling and "neon glow" effects when buttons are active.
• JavaScript (Gamepad API): The core logic uses the browser's native navigator.getGamepads() API. It polls the controller state 60 times per second (via requestAnimationFrame) and updates the SVG elements to reflect the current state.

Usage

1. Clone this repository.
2. Open index.html in a modern web browser (Chrome, Edge, or Firefox).
3. Connect your 8BitDo Ultimate 2C controller via USB or Bluetooth.
4. Press any button to activate the visualizer.
5. Toggle the "Show Debug Info" checkbox at the top to see raw axis values and button indices.

Control Mapping Table

The following mapping was determined experimentally on a Linux system. Note that mappings can sometimes vary slightly between operating systems (Windows vs. Linux/Android).

Digital Buttons

Physical Control	Gamepad API Index	Notes
A	Button 0
B	Button 1
X	Button 3	Note the gap (Button 2 is L4)
Y	Button 4
L1 (Left Bumper)	Button 6
R1 (Right Bumper)	Button 7
L2 (Left Trigger)	Button 8	Digital click at bottom of press
R2 (Right Trigger)	Button 9	Digital click at bottom of press
L4 (Extra Left)	Button 2	Located next to L1/L2
R4 (Extra Right)	Button 5	Located next to R1/R2
View (Back/-)	Button 10	Left of center cluster
Menu (Start/+)	Button 11	Right of center cluster
Home (Logo)	Button 12	Center of controller
L3 (Left Stick Click)	Button 13	Press down on left stick
R3 (Right Stick Click)	Button 14	Press down on right stick

Analog Controls (Axes)

Physical Control	Gamepad API Axis	Range / Values
Left Stick X	Axis 0	-1.0 (Left) to 1.0 (Right)
Left Stick Y	Axis 1	-1.0 (Up) to 1.0 (Down)
Right Stick X	Axis 2	-1.0 (Left) to 1.0 (Right)
Right Stick Y	Axis 5	-1.0 (Up) to 1.0 (Down)
L2 Trigger	Axis 3	-1.0 (Released) to 1.0 (Pressed)
R2 Trigger	Axis 4	-1.0 (Released) to 1.0 (Pressed)
D-Pad	Axis 9	Hat Switch (Discrete Values) Up: ~ -1.00 Right: ~ -0.43 Down: ~ 0.14 Left: ~ 0.71

Note: The Star and Profile buttons are handled internally by the controller firmware (for Turbo/Macros) and typically do not send events to the host device.