Device::USB::DevInterface(3pm) User Contributed Perl Documentation Device::USB::DevInterface(3pm)Device::USB::DevInterface
This class encapsulates a USB Device Interface and the methods that object would support.
NAME
Device::USB::DevInterface - Access a device interface returned by libusb.
VERSION
Version 0.11
SYNOPSIS
Device::USB:DevInterface provides a Perl object for accessing an interface of a configuration of a USB device using the libusb library.
use Device::USB;
my $usb = Device::USB->new();
my $dev = $usb->find_device( $VENDOR, $PRODUCT );
printf "Device: %04X:%04X
", $dev->idVendor(), $dev->idProduct();
$dev->open();
my $cfg = $dev->config()->[0];
my $inter = $cfg->interfaces()->[0];
print "Interface:", $inter->bInterfaceNumber(),
" name: ", $dev->get_string_simple($iter->iInterface()),
": endpoint count: ", $inter->nNumEndpoints(), "
";
See USB specification for an explanation of the attributes of an interface.
DESCRIPTION
This module defines a Perl object that represents the data associated with a USB device configuration's interface. The object provides
read-only access to the important data associated with the interface.
METHODS
There are several accessor methods that return data from the interface. Each is named after the field that they return. These accessors
include:
bInterfaceNumber
The 0-based number of this interface.
bAlternateSetting
Value used to select this alternate setting for the interface specified in bInterfaceNumber.
bNumEndpoints
Number of endpoints (excluding endpoint 0) available on this interface. If the value is 0, only the control interface is supported.
bInterfaceClass
Class code as specified by the USB-IF. A value of 0xff is a vendor-specific interface class.
bInterfaceSubClass
Subclass code specified by the USB-IF. If bInterfaceClass is not 0xff, this field must use only subclasses specified by the USB-IF.
bInterfaceProtocol
The InterfaceProtocol as specified by the USB-IF. A value of 0xff uses a vendor-specific protocol.
iInterface
Returns the index of the string descriptor describing this interface. The string can be retrieved using the method
"Device::USB::Device::get_string_simple".
endpoints
Returns a list of endpoint objects associated with this interface.
DIAGNOSTICS
This is an explanation of the diagnostic and error messages this module can generate.
DEPENDENCIES
This module depends on the Carp, Inline and Inline::C modules, as well as the strict and warnings pragmas. Obviously, libusb must be
available since that is the entire reason for the module's existence.
AUTHOR
G. Wade Johnson (wade at anomaly dot org) Paul Archer (paul at paularcher dot org)
Houston Perl Mongers Group
BUGS
Please report any bugs or feature requests to "bug-device-usb@rt.cpan.org", or through the web interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Device::USB>. I will be notified, and then you'll automatically be notified of progress on your
bug as I make changes.
ACKNOWLEDGEMENTS
Thanks go to various members of the Houston Perl Mongers group for input on the module. But thanks mostly go to Paul Archer who proposed
the project and helped with the development.
COPYRIGHT &; LICENSE
Copyright 2006 Houston Perl Mongers
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl v5.14.2 2008-06-02 Device::USB::DevInterface(3pm)
Check Out this Related Man Page
Device::USB::FAQ(3pm) User Contributed Perl Documentation Device::USB::FAQ(3pm)NAME
Device::USB::FAQ - Frequently Asked Questions for Device::USB
SYNOPSIS
perldoc Device::USB::FAQ
DESCRIPTION
This is an attempt to answer some of the frequently asked questions about the Device::USB module
QUESTIONS
Which platforms does Device::USB support?
"Device:USB" supports any platform that "libusb" supports. This list currently includes Linux, FreeBSD, NetBSD, OpenBSD, Darwin, and MacOS
X.
There is a port of the "libusb" library to the Windows environment called "LibUsb-Win32". Because I don't have a development environment
for testing this library, "Device::USB" does not yet support this library.
Do I have to use Device::USB as root?
By default, access to the USB devices on a Unix-based system appear to be limited to the root account. This usually causes access to most
of the "libusb" features to fail with a permission error.
Using the "Device::USB" module as root avoids this feature, but is not very satisfying from a security standpoint. (See the next question
for more options.)
How do I enable use of Device::USB as a non-root user?
Some of the attributes of USB devices are available to non-root users, but accessing many of the more interesting features require special
privileges. According to the libusb source, the "open()" function requires either device nodes to be present or the usbfs file system to
be mounted in specific locations. Those places in order are:
1) /dev/bus/usb - pre-2.6.11: via devfs / post-2.6.11: via udev
2) /proc/bus/usb - usbfs
Look in both locations on your system for which of these two methods your libusb will use.
No matter which method your system uses, you will probably want to create a separate group to control access. Run this command to add a
system group:
addgroup --system usb
or
groupadd --system usb
You can then add users to that group to allow access to your usb devices.
DEVFS / HOTPLUG
TODO
UDEV
If you use Debian/Ubuntu, look in the /etc/udev/permissions.rules file. If you want to allow global access to all usb devices, make this
change:
Change this:
SUBSYSTEM=="usb_device", MODE="0664"
To this:
SUBSYSTEM=="usb_device", MODE="0664", GROUP="usb"
After you reboot, all usb devices will inherit the mode and group specified.
If you want to only change permissions for certain devices, you can add this on one line and adjust the product and vendor IDs:
SUBSYSTEM=="usb_device", GROUP="usb",
SYSFS{idVendor}=="1234", SYSFS{idProduct}=="1234"
USBFS
The usbfs defaults to root as the user and group. This can be changed in the /etc/fstab by adding the following on one line:
none /proc/bus/usb usbfs noauto,
listuid=0,listgid=118,listmode=0664,
busuid=0,busgid=118,busmode=0775,
devuid=0,devgid=118,devmode=0664
0 0
The value 118 in the above should be replaced with the group id of your usb group (created above). The list* values are to allow listing
devices, the bus* is to control access to the bus directories and the dev* values control access to the device files. This approach does
not allow the kind of granular permission that the udev approach gives, so it is all or nothing unless permissions are changed
programmatically.
If your /etc/fstab file already has a line for /proc/bus/usb, add the options above to the line that is already there rather than adding
the new line. For example, you would change
usbfs /proc/bus/usb usbfs noauto 0 0
to
usbfs /proc/bus/usb usbfs noauto,
listuid=0,listgid=118,listmode=0664,
busuid=0,busgid=118,busmode=0775,
devuid=0,devgid=118,devmode=0664
0 0
Once again, this needs to be all on one line with the "" characters removed.
SEE ALSO
Device::USB and the "libusb" library site at <http://libusb.sourceforge.net/>.
AUTHOR
G. Wade Johnson (wade at anomaly dot org) Paul Archer (paul at paularcher dot org)
Houston Perl Mongers Group
ACKNOWLEDGEMENTS
Thanks go to various users who submitted questions and answers for the list. In particular, Anthony L. Awtrey who contributed the first FAQ
answer.
COPYRIGHT &; LICENSE
Copyright 2006 Houston Perl Mongers
This document is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl v5.14.2 2006-09-03 Device::USB::FAQ(3pm)