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https://github.com/larskanis/libusb
Access USB devices from Ruby via libusb-1.x
https://github.com/larskanis/libusb
Last synced: 12 days ago
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Access USB devices from Ruby via libusb-1.x
- Host: GitHub
- URL: https://github.com/larskanis/libusb
- Owner: larskanis
- License: lgpl-3.0
- Created: 2011-03-19T19:45:30.000Z (over 13 years ago)
- Default Branch: master
- Last Pushed: 2024-01-09T12:10:22.000Z (10 months ago)
- Last Synced: 2024-01-30T17:21:46.136Z (10 months ago)
- Language: Ruby
- Homepage: http://rubygems.org/gems/libusb
- Size: 2.46 MB
- Stars: 153
- Watchers: 22
- Forks: 34
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
- Changelog: History.md
- License: COPYING
Awesome Lists containing this project
README
[](https://travis-ci.com/larskanis/libusb)
[](https://ci.appveyor.com/project/larskanis/libusb/branch/master)
Access USB devices from Ruby
============================
LIBUSB is a Ruby binding that gives Ruby programmers access to arbitrary USB devices.
* [libusb](http://libusb.info) is a library that gives full access to devices connected via the USB bus. No special kernel driver is thus necessary for accessing USB devices.
* This Ruby binding supports the API version 1.0 of [libusb](http://libusb.info). Note that the old "legacy" version 0.1.x of libusb uses a completely different API that is covered by the ruby extension [ruby-usb](http://www.a-k-r.org/ruby-usb/) .
LIBUSB for Ruby is covered by the GNU Lesser General Public License version 3.
Features
--------
* Access to descriptors of devices, configurations, interfaces, settings and endpoints
* Synchronous and asynchronous communication for bulk, control, interrupt and isochronous transfers
* Support for USB-3.0 descriptors and bulk streams
* Compatibility layer for [ruby-usb](http://www.a-k-r.org/ruby-usb/) (API based on libusb-0.1). See {::USB} for description.
Synopsis
--------
```ruby
require "libusb"
usb = LIBUSB::Context.new
device = usb.devices(idVendor: 0x04b4, idProduct: 0x8613).first
device.open_interface(0) do |handle|
handle.control_transfer(bmRequestType: 0x40, bRequest: 0xa0, wValue: 0xe600, wIndex: 0x0000, dataOut: 1.chr)
end
```
{LIBUSB::Context#devices} is used to get all or only particular devices.
After {LIBUSB::Device#open_interface opening and claiming} the {LIBUSB::Device} the resulting {LIBUSB::DevHandle} can be
used to communicate with the connected USB device
by {LIBUSB::DevHandle#control_transfer}, {LIBUSB::DevHandle#bulk_transfer},
{LIBUSB::DevHandle#interrupt_transfer} or by using the {LIBUSB::Transfer} classes.
A {LIBUSB::Device} can also be used to retrieve information about it,
by using the device descriptor attributes.
A {LIBUSB::Device} could have several configurations. You can then decide of which
configuration to enable. You can only enable one configuration at a time.
Each {LIBUSB::Configuration} has one or more interfaces. These can be seen as functional group
performing a single feature of the device.
Each {LIBUSB::Interface} has at least one {LIBUSB::Setting}. The first setting is always default.
An alternate setting can be used independent on each interface.
Each {LIBUSB::Setting} specifies it's own set of communication endpoints.
Each {LIBUSB::Endpoint} specifies the type of transfer, direction, polling interval and
maximum packet size.
See [the documentation](http://rubydoc.info/gems/libusb/frames) for a full API description.
Prerequisites
-------------
* Linux, MacOS or Windows system with Ruby MRI 2.x/3.x, JRuby or recent version of Rubinius
* Optionally: [libusb](http://libusb.info) C-library version 1.0.8 or any newer version.
The system libusb library can be installed like so:
* Debian or Ubuntu:
```
$ sudo apt-get install libusb-1.0-0
```
* MacOS: install with homebrew:
```
$ brew install libusb
```
or macports:
```
$ port install libusb
```
* Windows: libusb.gem already comes with a precompiled `libusb.dll`, but you need to install a device driver (see [below](#usage-on-windows))
Install
-------
$ gem install libusb
While ```gem install``` the system is checked for a usable libusb library installation.
If none could be found, a bundled libusb version is built and used, instead.
Latest code can be used in this way:
$ git clone git://github.com/larskanis/libusb.git
$ bundle
$ rake install_gem
Troubleshooting
------------------------
In order to implement a driver for a USB device, it's essential to have a look at the packets that are send to and received back from the USB device. [Wireshark](https://www.wireshark.org) has builtin capabilities to sniff USB traffic. On Linux you possibly need to load the usbmon kernel module before start:
```
sudo modprobe usbmon
```
On Windows it's possible to sniff USB, if the USB kernel driver was installed by the Wireshark setup.
Device hotplug support
----------------------
Support for device hotplugging can be used, if ```LIBUSB.has_capability?(:CAP_HAS_HOTPLUG)``` returns ```true```.
This requires libusb-1.0.16 or newer on Linux or MacOS. Windows support is [still on the way](https://github.com/libusbx/libusbx/issues/9).
A hotplug event handler can be registered with {LIBUSB::Context#on_hotplug_event}.
You then need to call {LIBUSB::Context#handle_events} in order to receive any events.
This can be done as blocking calls (possibly in it's own thread) or by using {LIBUSB::Context#pollfds} to
detect any events to handle.
Usage on Windows
----------------
In contrast to Linux, any access to an USB device by LIBUSB on Windows requires a proper driver
installed in the system. Fortunately creating such a driver is quite easy with
[Zadig](http://zadig.akeo.ie/). Select the interesting USB device,
choose WinUSB driver and press "Install Driver". That's it. You may take the generated output directory
with it's INI-file and use it for driver installations on other 32 or 64 bit Windows
systems.
Binary gems for Windows and Linux
---------------------------
The Libusb gem is provided as source gem and as binary gems for Windows and Linux operating systems on [rubygems.org](https://rubygems.org/gems/libusb).
The binary version is usually preferred, but the source version of the gem can be enforced by:
$ gem install libusb --platform ruby
Libusb gem can be cross built for Windows and Linux, using the [rake-compiler-dock](https://github.com/larskanis/rake-compiler-dock) .
Just run:
$ rake gem:native
If everything works, there are several platform specific gem files (like `libusb-VERSION-x64-mingw32.gem`) in the pkg
directory.
EventMachine integration
------------------------
Libusb for Ruby comes with an experimental integration to [EventMachine](http://rubyeventmachine.com/).
That API is currently proof of concept - see {LIBUSB::Context#eventmachine_register}.
If you're experienced with EventMachine, please leave a comment.
Testing LIBUSB gem
------------------
Libusb for Ruby has a bundled test suite which verifies proper working of many functions of the library.
Only a small subset of these tests are executed on Github Actions due to the missing USB functions in the CI environments.
They just verify that the libusb library can be installed and called and that very basic functions are working.
To run the tests against real devices the following procedure should be done:
```sh
$ # Connect a USB mass strorage device. It is used read-only.
$ sudo chown $USER /dev/bus/usb/*/*
$ rake test
```
While the tests are running a second arbitrary USB device is requested to be connected and shortly after disconnected again.
There are only 5 seconds timeout for connecting and disconnecting, so that the device should have be ready.
Some USB mass storage devices are not compatible to the tests, so that it's best to try out different models to find some that doesn't fail.
Resources
---------
* Project's home page: http://github.com/larskanis/libusb
* API documentation: http://rubydoc.info/gems/libusb/frames
* Mailinglist: http://rubyforge.org/mailman/listinfo/libusb-hackers
* Overall introduction to USB: http://www.usbmadesimple.co.uk
Todo
----
* stabilize EventMachine interface