module USB

USB module is a binding for libusb.

It needs appropriate privilege to access USB. For example, the process should be an member of plugdev group on Debin GNU/Linux (etch).

Example¶ ↑

list up USB devices

require 'usb'
require 'pp'
pp USB.devices
#=>
[#<USB::Device 001/001 0000:0000 Linux 2.6.17-2-486 uhci_hcd UHCI Host Controller 0000:00:1d.0 (Full speed Hub)>,
 #<USB::Device 002/001 0000:0000 Linux 2.6.17-2-486 uhci_hcd UHCI Host Controller 0000:00:1d.1 (Full speed Hub)>,
 #<USB::Device 003/001 0000:0000 Linux 2.6.17-2-486 uhci_hcd UHCI Host Controller 0000:00:1d.2 (Full speed Hub)>,
 #<USB::Device 004/001 0000:0000 Linux 2.6.17-2-486 ehci_hcd EHCI Host Controller 0000:00:1d.7 (Hi-speed Hub with single TT)>]

find a device by bus id and device id

# find the device "004/001" in the above list.
dev = USB.find_bus(4).find_device(1)
p dev
#=>
#<USB::Device 004/001 0000:0000 Linux 2.6.17-2-486 ehci_hcd EHCI Host Controller 0000:00:1d.7 (Hi-speed Hub with single TT)>

open a device

dev.open {|handle| p handle }
#=>
#<USB::DevHandle:0xa7d94688>

USB overview¶ ↑

A host has busses.
A bus has devices.
A device has configurations.
A configuration has interfaces.
A interface has settings.
A setting has endpoints.

——– libusb binding initialization ——–

Public Class Methods

busses() click to toggle source

# File lib/usb.rb, line 64
def USB.busses
  result = []
  bus = USB.first_bus
  while bus
    result << bus
    bus = bus.next
  end
  result.sort_by {|b| b.dirname }
end

configurations() click to toggle source

# File lib/usb.rb, line 75
def USB.configurations() USB.devices.map {|d| d.configurations }.flatten end

devices() click to toggle source

# File lib/usb.rb, line 74
def USB.devices() USB.busses.map {|b| b.devices }.flatten end

each_device_by_class(devclass, subclass=nil, protocol=nil) { |dev| ... } click to toggle source

searches devices by USB device class, subclass and protocol.

# find hubs.
USB.each_device_by_class(USB::USB_CLASS_HUB) {|d| p d }'

# find Full speed Hubs
USB.each_device_by_class(USB::USB_CLASS_HUB, 0, 0) {|d| p d }'

# find Hi-speed Hubs with single TT
USB.each_device_by_class(USB::USB_CLASS_HUB, 0, 1) {|d| p d }'

# find Hi-speed Hubs with multiple TT
USB.each_device_by_class(USB::USB_CLASS_HUB, 0, 2) {|d| p d }'

# File lib/usb.rb, line 103
def USB.each_device_by_class(devclass, subclass=nil, protocol=nil)
  USB.devices.each {|dev|
    if dev.bDeviceClass == USB::USB_CLASS_PER_INTERFACE
      found = dev.settings.any? {|s|
                s.bInterfaceClass == devclass &&
                (!subclass || s.bInterfaceSubClass == subclass) &&
                (!protocol || s.bInterfaceProtocol == protocol) }
    else
      found = dev.bDeviceClass == devclass &&
              (!subclass || dev.bDeviceSubClass == subclass) &&
              (!protocol || dev.bDeviceProtocol == protocol)
    end
    yield dev if found
  }
  nil
end

endpoints() click to toggle source

# File lib/usb.rb, line 78
def USB.endpoints() USB.settings.map {|d| d.endpoints }.flatten end

find_bus(n) click to toggle source

# File lib/usb.rb, line 80
def USB.find_bus(n)
  bus = USB.first_bus
  while bus
    return bus if n == bus.dirname.to_i
    bus = bus.next
  end
  return nil
end

find_busses() click to toggle source

::find_busses

static VALUE
rusb_find_busses(VALUE cUSB)
{
  st_foreach(bus_objects, revoke_data_i, 0);
  st_foreach(device_objects, revoke_data_i, 0);
  st_foreach(config_descriptor_objects, revoke_data_i, 0);
  st_foreach(interface_objects, revoke_data_i, 0);
  st_foreach(interface_descriptor_objects, revoke_data_i, 0);
  st_foreach(endpoint_descriptor_objects, revoke_data_i, 0);
  return INT2NUM(usb_find_busses());
}

find_devices() click to toggle source

::find_devices

static VALUE
rusb_find_devices(VALUE cUSB)
{
  return INT2NUM(usb_find_devices());
}

first_bus() click to toggle source

::first_bus

static VALUE
rusb_first_bus(VALUE cUSB)
{
  struct usb_bus *bus = usb_get_busses();
  return rusb_bus_make(bus, Qnil);
}

interfaces() click to toggle source

# File lib/usb.rb, line 76
def USB.interfaces() USB.configurations.map {|d| d.interfaces }.flatten end

settings() click to toggle source

# File lib/usb.rb, line 77
def USB.settings() USB.interfaces.map {|d| d.settings }.flatten end