/WebUSB

Documentation on my experiments with WebUSB

Primary LanguageJavaScript

WebUSB

WebUSB lets us interact with USB devices from Chrome using Javascript. WebUSB is a DRAFT spec, but is supported in CHROME.

TLDR What do I need to know?

  • Requires Chrome version 61 or higher
  • The Nonin works out of the box on MacOS and Linux.
  • Windows 10 requires a custom driver be used to support the Nonin 3230 Pulse Oximeter. details below

Interesting... tell me more.

I highly recommend reading this short post from Google. It covers most of what you will need to know.

Access USB Devices on the Web.

A few notes about using WebUSB

HTTPS only

Because this API is a powerful new feature added to the Web, Chrome aims to make it available only to secure contexts. This means you'll need to build with TLS in mind.

A Feature-Policy wil be required

A feature policy is a mechanism that allows developers to selectively enable and disable various browser features and APIs. It can be defined via a HTTP header and/or an iframe "allow" attribute.

You can define a feature that controls whether the usb attribute is exposed on the Navigator object, or in other words if you allow WebUSB.

Below is an example of a header policy where WebUSB is allowed *;

Feature-Policy: usb *;

Below is another example of a different container policy where USB is allowed:

<iframe allowpaymentrequest allow=’usb fullscreen’></iframe>

User gesture required

As a security feature, getting access to connected USB devices with navigator.usb.requestDevice must be called via a user gesture like a touch or mouse click.

Whats this about custom drivers on Windows?

Chrome relies on libusb for its USB device communication. When the Nonin 3230 is plugged into a computer running Windows 10, the operating system assigns the Nonin a generic windows driver: USBSerial.

This can be worked around by replacing this driver with a generic one: WinUSB. We do this by creating a "custom driver"

Custom Windows Drivers for Nonin 3230 PulseOx

To Install this Custom Driver, open the Device Manager on Windows, locate the Nonin device. (It will show up as a COM port device) and manually update the device driver. Update Driver / Browse for Drivers on my Computer and point to /drivers/windows/nonin-custom in this repo.

An example driver created for the Microsoft Surface Pro can be found in: drivers/windows/nonin-custom

This driver should be fairly universal, but at the time of this writing has only been tested on the Microsoft Surface and Windows 10.

This driver was generated using Zadig https://zadig.akeo.ie/

Resources

tools

  • Zadig Tool for replacing drivers on windows
  • PnPUtil.exe a command line tool that lets an administrator install/update device drivers on Windows systems.

knowledge

helpful internet posts