This repository contains an Arduino library for WebUSB-enabling your sketches. Example sketches and JavaScript code are available in the demos directory.

The WebUSB object is a copy of the Arduino SDK's built-in USB serial library. It creates a WebUSB-compatible vendor-specific interface rather than one marked as USB CDC-ACM. This prevents operating system drivers from claiming the device and making it inaccessible to the browser. This library also implements:

• The WebUSB landing page descriptor, providing a hint to the browser about what page the user should navigate to to interact with the device. In Google Chrome the presence of this descriptor causes the browser to display a notification when the device is connected. The user can click on this notification to navigate directly to the provided URL.
• Microsoft OS 2.0 Descriptors which instruct the Windows operating system (8.1 and above) to automatically the WinUSB.sys driver so that the browser can connect to the device.

WebUSB requires an Arduino model that gives the sketch complete control over the USB hardware. This library has been tested with the following models:

• Arduino Leonardo
• Arduino/Genuino Micro
• Arduino/Genuino Zero
• Arduino MKR1000
• Arduino MKRZero
• Arduino MKRFox1200
• Adafruit Feather 32u4

1. Install at least version 1.6.11 of the Arduino IDE.

2. The WebUSB library provides all the extra low-level USB code necessary for WebUSB support except for one thing: Your device must be upgraded from USB 2.0 to USB 2.1. To do this go into the SDK installation directory and open hardware/arduino/avr/cores/arduino/USBCore.h. Then find the line #define USB_VERSION 0x200 and change 0x200 to 0x210. That's it!

macOS: Right click on the Ardunio application icon and then click on show package contents menu item. Navigate to Contents/Java/hardware/arduino/avr/cores/arduino/USBCore.h

Warning: Windows requires USB 2.1 devices to present a Binary Object Store (BOS) descriptor when they are enumerated. The code to support this is added by including the "WebUSB" library in your sketch. If you do not include this library after making this change to the SDK then Windows will no longer be able to recognize your device and you will not be able to upload new sketches to it.

3. Copy (or symlink) the library/WebUSB directory from this repository into the libraries folder in your sketchbooks directory.

4. Launch the Arduino IDE. You should see "WebUSB" as an option under "Sketch > Include Library".

5. Load up demos/rgb/sketch/sketch.ino and program it to your device.

6. When the sketch is finished uploading you should see a notification from Chrome: "Go to https://webusb.github.io/arduino/demos/ to connect." Try it out!

Windows: This notification is currently disabled in Chrome on Windows due to Chromium issue 656702. Implementation of new, more stable USB support for Windows is tracked on Chromium issues 422562 and 637404.

Android: This notification is not supported on Android because of OS limitations that prevent the browser from connecting to a device without user interaction.