Python 3.7.4 : Testing the PyUSB python module.

This python module named PyUSB can be found at pypi website.

[mythcat@desk scripts]$ pip3 install pyusb --user
Collecting pyusb
...
Successfully installed pyusb-1.0.2

Let' see some usb device with lsusb command:

[mythcat@desk scripts]$ lsusb
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 004: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 003: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

First you need to set this to avoid the error: Access denied (insufficient permissions.

[mythcat@desk scripts]$ ll  /dev/bus/usb/001/004
crw-rw-r--. 1 root root 189, 3 Oct 10 20:34 /dev/bus/usb/001/004
[mythcat@desk scripts]$ chmod a+rw /dev/bus/usb/001/004
chmod: changing permissions of '/dev/bus/usb/001/004': Operation not permitted
[mythcat@desk scripts]$ sudo chmod a+rw /dev/bus/usb/001/004
[sudo] password for mythcat: 
[mythcat@desk scripts]$ ll  /dev/bus/usb/001/004
crw-rw-rw-. 1 root root 189, 3 Oct 10 20:34 /dev/bus/usb/001/004

The script is simple:

import sys
  
import usb.core
import usb.util
print(usb.__version__)
busses = usb.busses()
for bus in busses:
    devices = bus.devices
    for dev in devices:
        if dev != None:
            try:
                usd_dev = usb.core.find(idVendor=dev.idVendor, idProduct=dev.idProduct)
                print(usb_dev)
            except:
                pass
# 1a40:0101
dev  = usb.core.find(idVendor=0x1a40, idProduct=0x0101)
print ("The 8087:0024 is : ", dev)
if dev is None:
    raise ValueError("Device not found!")
else:

    if dev.is_kernel_driver_active(0):
        try:
                dev.detach_kernel_driver(0)
                print ("kernel driver detached")
        except usb.core.USBError as e:
                sys.exit("Could not detach kernel driver: %s" % str(e))
    else:
        print ("no kernel driver attached")
    try:
        usb.util.claim_interface(dev, 0)
        print ("claimed device")
    except:
        sys.exit("Could not claim the device: %s" % str(e))
    try:
        dev.set_configuration()
        dev.reset()
    except usb.core.USBError as e:
        sys.exit("Could not set configuration: %s" % str(e))

usb.util.release_interface(dev,interface)
dev.attach_kernel(interface

The result of this python script is this:

[mythcat@desk scripts]$ python3 usb_test.py 
1.0.2
The 8087:0024 is :  DEVICE ID 1a40:0101 on Bus 001 Address 004 =================
 bLength                :   0x12 (18 bytes)
 bDescriptorType        :    0x1 Device
 bcdUSB                 :  0x200 USB 2.0
 bDeviceClass           :    0x9 Hub
 bDeviceSubClass        :    0x0
 bDeviceProtocol        :    0x1
 bMaxPacketSize0        :   0x40 (64 bytes)
 idVendor               : 0x1a40
 idProduct              : 0x0101
 bcdDevice              :  0x111 Device 1.11
 iManufacturer          :    0x0 
 iProduct               :    0x1 USB 2.0 Hub
 iSerialNumber          :    0x0 
 bNumConfigurations     :    0x1
  CONFIGURATION 1: 100 mA ==================================
   bLength              :    0x9 (9 bytes)
   bDescriptorType      :    0x2 Configuration
   wTotalLength         :   0x19 (25 bytes)
   bNumInterfaces       :    0x1
   bConfigurationValue  :    0x1
   iConfiguration       :    0x0 
   bmAttributes         :   0xe0 Self Powered, Remote Wakeup
   bMaxPower            :   0x32 (100 mA)
    INTERFACE 0: Hub =======================================
     bLength            :    0x9 (9 bytes)
     bDescriptorType    :    0x4 Interface
     bInterfaceNumber   :    0x0
     bAlternateSetting  :    0x0
     bNumEndpoints      :    0x1
     bInterfaceClass    :    0x9 Hub
     bInterfaceSubClass :    0x0
     bInterfaceProtocol :    0x0
     iInterface         :    0x0 
      ENDPOINT 0x81: Interrupt IN ==========================
       bLength          :    0x7 (7 bytes)
       bDescriptorType  :    0x5 Endpoint
       bEndpointAddress :   0x81 IN
       bmAttributes     :    0x3 Interrupt
       wMaxPacketSize   :    0x1 (1 bytes)
       bInterval        :    0xc
kernel driver detached
claimed device
Could not set configuration: [Errno 16] Resource busy

Set permisions for next usb:

[mythcat@desk scripts]$ ll /dev/bus/usb/001/003
crw-rw-rw-. 1 root root 189, 2 Oct 10 20:34 /dev/bus/usb/001/003

Te next source code will read the mouse device:

#!/usr/bin/python
import sys
import usb.core
import usb.util
# decimal vendor and product values
#dev = usb.core.find(idVendor=1118, idProduct=1917)
# or, uncomment the next line to search instead by the hexidecimal equivalent
# 093a:2510
dev = usb.core.find(idVendor=0x093a, idProduct=0x2510)
# first endpoint
interface = 0
endpoint = dev[0][(0,0)][0]
# if the OS kernel already claimed the device, which is most likely true
# thanks to http://stackoverflow.com/questions/8218683/pyusb-cannot-set-configuration
if dev.is_kernel_driver_active(interface) is True:
  # tell the kernel to detach
  dev.detach_kernel_driver(interface)
  # claim the device
  usb.util.claim_interface(dev, interface)
collected = 0
attempts = 50
while collected < attempts :
    try:
        data = dev.read(endpoint.bEndpointAddress,endpoint.wMaxPacketSize)
        collected += 1
        print (data)
    except usb.core.USBError as e:
        data = None
        if e.args == ('Operation timed out',):
            continue
# release the device
usb.util.release_interface(dev, interface)
# reattach the device to the OS kernel
dev.attach_kernel_driver(interface)

The output of mouse moves is this:

[mythcat@desk scripts]$ python3 usb_mouse.py 
[mythcat@desk scripts]$ python3 usb_mouse.py 
array('B', [0, 254, 255, 0])
array('B', [0, 253, 2, 0])
array('B', [0, 252, 3, 0])
array('B', [0, 251, 3, 0])
array('B', [0, 252, 3, 0])
array('B', [0, 254, 1, 0])
array('B', [0, 253, 2, 0])
array('B', [0, 255, 1, 0])
array('B', [0, 255, 4, 0])
array('B', [0, 0, 3, 0])
array('B', [0, 0, 3, 0])
array('B', [0, 0, 2, 0])
array('B', [0, 0, 2, 0])
array('B', [0, 2, 1, 0])
array('B', [0, 4, 1, 0])
array('B', [0, 3, 0, 0])
array('B', [0, 3, 0, 0])
array('B', [0, 1, 0, 0])

Using PyUSB with python 3.x .

C:\Python34\Scripts>pip3.4.exe install PyUSB
Downloading/unpacking PyUSB
  Running setup.py (path:C:\Users\mythcat\AppData\Local\Temp\pip_build_mythcat\PyUSB\setup.py) 
egg_info for package PyUSB

Installing collected packages: PyUSB
  Running setup.py install for PyUSB

Successfully installed PyUSB
Cleaning up...

Now you need to install this filter from here.
If not, you can get errors like this: raise NoBackendError('No backend available')
usb.core.NoBackendError: No backend available
Let's make a simple test example:

import usb.core
import usb.util
import sys

class find_class(object):
    def __init__(self, class_):
        self._class = class_
    def __call__(self, device):
        # first, let's check the device
        if device.bDeviceClass == self._class:
            return True
        # ok, transverse all devices to find an
        # interface that matches our class
        for cfg in device:
            # find_descriptor: what's it?
            intf = usb.util.find_descriptor(
                                        cfg,
                                        bInterfaceClass=self._class
                                )
            if intf is not None:
                return True

        return False

all = usb.core.find(find_all=1, custom_match=find_class(7))
print (all)

And show the result:

C:\Python34>python.exe usb_devs.py
< generator 0x0000000003d8d5e8="" at="" device_iter="" object="" >