def find_descriptor(desc, find_all=False, custom_match=None, **args):
r"""Find an inner descriptor.
find_descriptor works in the same way as the core.find() function does,
but it acts on general descriptor objects. For example, suppose you
have a Device object called dev and want a Configuration of this
object with its bConfigurationValue equals to 1, the code would
be like so:
>>> cfg = util.find_descriptor(dev, bConfigurationValue=1)
You can use any field of the Descriptor as a match criteria, and you
can supply a customized match just like core.find() does. The
find_descriptor function also accepts the find_all parameter to get
an iterator instead of just one descriptor.
"""
def desc_iter(**kwargs):
for d in desc:
tests = (val == getattr(d, key) for key, val in kwargs.items())
if _interop._all(tests) and (custom_match is None or custom_match(d)):
yield d
if find_all:
return desc_iter(**args)
else:
try:
return _interop._next(desc_iter(**args))
except StopIteration:
return None
def find_descriptor(desc, find_all=False, custom_match=None, **args):
r"""Find an inner descriptor.
find_descriptor works in the same way the core.find() function does,
but it acts on general descriptor objects. For example, suppose you
have a Device object called dev and want a Configuration of this
object with its bConfigurationValue equals to 1, the code would
be like so:
>>> cfg = util.find_descriptor(dev, bConfigurationValue=1)
You can use any field of the Descriptor as a match criteria, and you
can supply a customized match just like core.find() does. The
find_descriptor function also accepts the find_all parameter to get
a list of descriptor instead of just one.
"""
def desc_iter(k, v):
for d in desc:
if (custom_match is None or custom_match(d)) and _interop._reduce(
lambda a, b: a and b, map(operator.eq, v, map(lambda i: getattr(d, i), k)), True
):
yield d
k, v = args.keys(), args.values()
if find_all:
return [d for d in desc_iter(k, v)]
else:
try:
return _interop._next(desc_iter(k, v))
except StopIteration:
return None
def find_descriptor(desc, find_all=False, custom_match=None, **args):
r"""Find an inner descriptor.
find_descriptor works in the same way as the core.find() function does,
but it acts on general descriptor objects. For example, suppose you
have a Device object called dev and want a Configuration of this
object with its bConfigurationValue equals to 1, the code would
be like so:
>>> cfg = util.find_descriptor(dev, bConfigurationValue=1)
You can use any field of the Descriptor as a match criteria, and you
can supply a customized match just like core.find() does. The
find_descriptor function also accepts the find_all parameter to get
an iterator instead of just one descriptor.
"""
def desc_iter(**kwargs):
for d in desc:
tests = (val == getattr(d, key) for key, val in kwargs.items())
if _interop._all(tests) and (custom_match is None or custom_match(d)):
yield d
if find_all:
return desc_iter(**args)
else:
try:
return _interop._next(desc_iter(**args))
except StopIteration:
return None
def find_descriptor(desc, find_all=False, custom_match=None, **args):
r"""Find an inner descriptor.
find_descriptor works in the same way as the core.find() function does,
but it acts on general descriptor objects. For example, suppose you
have a Device object called dev and want a Configuration of this
object with its bConfigurationValue equals to 1, the code would
be like so:
>>> cfg = util.find_descriptor(dev, bConfigurationValue=1)
You can use any field of the Descriptor as a match criteria, and you
can supply a customized match just like core.find() does. The
find_descriptor function also accepts the find_all parameter to get
an iterator instead of just one descriptor.
"""
def desc_iter(k, v):
for d in desc:
if (custom_match is None or custom_match(d)) and \
_interop._reduce(
lambda a, b: a and b,
map(
operator.eq,
v,
map(lambda i: getattr(d, i), k)
),
True
):
yield d
k, v = args.keys(), args.values()
if find_all:
return desc_iter(k, v)
else:
try:
return _interop._next(desc_iter(k, v))
except StopIteration:
return None
def find(find_all=False, backend=None, custom_match=None, **args):
r"""Find an USB device and return it.
find() is the function used to discover USB devices. You can pass as
arguments any combination of the USB Device Descriptor fields to match a
device. For example:
find(idVendor=0x3f4, idProduct=0x2009)
will return the Device object for the device with idVendor field equals
to 0x3f4 and idProduct equals to 0x2009.
If there is more than one device which matchs the criteria, the first one
found will be returned. If a matching device cannot be found the function
returns None. If you want to get all devices, you can set the parameter
find_all to True, then find will return an iterator with all matched devices.
If no matching device is found, it will return an empty iterator. Example:
for printer in find(find_all=True, bDeviceClass=7):
print (printer)
This call will get all the USB printers connected to the system. (actually
may be not, because some devices put their class information in the
Interface Descriptor).
You can also use a customized match criteria:
dev = find(custom_match = lambda d: d.idProduct=0x3f4 and d.idvendor=0x2009)
A more accurate printer finder using a customized match would be like
so:
def is_printer(dev):
import usb.util
if dev.bDeviceClass == 7:
return True
for cfg in dev:
if usb.util.find_descriptor(cfg, bInterfaceClass=7) is not None:
return True
for printer in find(find_all=True, custom_match = is_printer):
print (printer)
Now even if the device class code is in the interface descriptor the
printer will be found.
You can combine a customized match with device descriptor fields. In this
case, the fields must match and the custom_match must return True. In the
our previous example, if we would like to get all printers belonging to the
manufacturer 0x3f4, the code would be like so:
printers = list(find(find_all=True, idVendor=0x3f4, custom_match=is_printer))
If you want to use find as a 'list all devices' function, just call
it with find_all = True:
devices = list(find(find_all=True))
Finally, you can pass a custom backend to the find function:
find(backend = MyBackend())
PyUSB has builtin backends for libusb 0.1, libusb 1.0 and OpenUSB. If you
do not supply a backend explicitly, find() function will select one of the
predefineds backends according to system availability.
Backends are explained in the usb.backend module.
"""
def device_iter(k, v):
for dev in backend.enumerate_devices():
d = Device(dev, backend)
if _interop._reduce(
lambda a, b: a and b,
map(operator.eq, v, map(lambda i: getattr(d, i), k)),
True) and (custom_match is None or custom_match(d)):
yield d
if backend is None:
import usb.backend.libusb1 as libusb1
import usb.backend.libusb0 as libusb0
import usb.backend.openusb as openusb
for m in (libusb1, openusb, libusb0):
backend = m.get_backend()
if backend is not None:
_logger.info('find(): using backend "%s"', m.__name__)
break
else:
raise ValueError('No backend available')
k, v = args.keys(), args.values()
if find_all:
return device_iter(k, v)
else:
try:
return _interop._next(device_iter(k, v))
except StopIteration:
return None
def find(find_all=False, backend = None, custom_match = None, **args):
r"""Find an USB device and return it.
find() is the function used to discover USB devices.
You can pass as arguments any combination of the
USB Device Descriptor fields to match a device. For example:
find(idVendor=0x3f4, idProduct=0x2009)
will return the Device object for the device with
idVendor Device descriptor field equals to 0x3f4 and
idProduct equals to 0x2009.
If there is more than one device which matchs the criteria,
the first one found will be returned. If a matching device cannot
be found the function returns None. If you want to get all
devices, you can set the parameter find_all to True, then find
will return an list with all matched devices. If no matching device
is found, it will return an empty list. Example:
printers = find(find_all=True, bDeviceClass=7)
This call will get all the USB printers connected to the system.
(actually may be not, because some devices put their class
information in the Interface Descriptor).
You can also use a customized match criteria:
dev = find(custom_match = lambda d: d.idProduct=0x3f4 and d.idvendor=0x2009)
A more accurate printer finder using a customized match would be like
so:
def is_printer(dev):
import usb.util
if dev.bDeviceClass == 7:
return True
for cfg in dev:
if usb.util.find_descriptor(cfg, bInterfaceClass=7) is not None:
return True
printers = find(find_all=True, custom_match = is_printer)
Now even if the device class code is in the interface descriptor the
printer will be found.
You can combine a customized match with device descriptor fields. In this
case, the fields must match and the custom_match must return True. In the our
previous example, if we would like to get all printers belonging to the
manufacturer 0x3f4, the code would be like so:
printers = find(find_all=True, idVendor=0x3f4, custom_match=is_printer)
If you want to use find as a 'list all devices' function, just call
it with find_all = True:
devices = find(find_all=True)
Finally, you may pass a custom backend to the find function:
find(backend = MyBackend())
PyUSB has builtin backends for libusb 0.1, libusb 1.0 and OpenUSB.
If you do not supply a backend explicitly, find() function will select
one of the predefineds backends according to system availability.
Backends are explained in the usb.backend module.
"""
def device_iter(k, v):
for dev in backend.enumerate_devices():
d = Device(dev, backend)
if _interop._reduce(
lambda a, b: a and b,
map(
operator.eq,
v,
map(lambda i: getattr(d, i), k)
),
True
) and (custom_match is None or custom_match(d)):
yield d
if backend is None:
import usb.backend.libusb1 as libusb1
import usb.backend.libusb0 as libusb0
import usb.backend.openusb as openusb
for m in (libusb1, openusb, libusb0):
backend = m.get_backend()
if backend is not None:
_logger.info('find(): using backend "%s"', m.__name__)
break
else:
raise ValueError('No backend available')
k, v = args.keys(), args.values()
if find_all:
return [d for d in device_iter(k, v)]
else:
try:
return _interop._next(device_iter(k, v))
except StopIteration:
return None
