No backend available ошибка

wovano

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I had a similar issue recently trying to talk to a USB device I am developing. I scoured the web looking for libusb-1.0.dll’s and had no luck. I found source code, but nothing built and ready to install. I ended up installing the libusb-win32 binaries, which is the libusb0.dll.

PyUSB will search for libusb-1.0, libusb0, and openUSB backends.

libusb0.dll was already on my system, but something was still not set up right, do PyUSB was not working.

I followed the directions here to download and install the driver using the GUI tools provided to install the filter driver, and the INF wizard. Note, it didn’t work until I ran the INF wizard.

I’m pretty new to programming and I’ve found the lack of clear documentation/examples to string this all together rather frustrating.

answered Dec 26, 2012 at 22:04

2021 and the problem still occurs on Windows (Windows 10). I solved it by installing pyusb and libusb and adding libusb path to Windows environment:

1. pip install pyusb
2. pip install libusb
3. libusb-1.0.dll will be automatically added to:

\venv\Lib\site-packages\libusb\_platform\_windows\x64
and
\venv\Lib\site-packages\libusb\_platform\_windows\x32

1. Now just add those paths (the full path) to Windows Path and restart CMD / PyCharm.

answered Jun 21, 2021 at 7:56

I am using Python 2.6.5, libusb-win32-device.bin-0.1.12.1 and pyusb-1.0.0-a0 on a windows XP system and kept receiving ValueError: No backend available.

Since there wasn’t any real help on the web for this problem I spent a lot of time finding that ctypes util.py uses the Path variable to find the library file. My path did not include windows\system32 and PYUSB didn’t find the library. I updated the path variable and now the USB is working.

There’s a simpler solution.

Download and unpack to C:\PATH the libusb-1.0.20 from download link

Then try this line:

backend = usb.backend.libusb1.get_backend(find_library=lambda x: "C:\\PATH\\libusb-1.0.20\\MS32\\dll\\libusb-1.0.dll")
usb_devices = usb.core.find(backend=backend, find_all=True)

Depending on your system, try either MS64 or MS32 version of the .dll

import usb.core
import usb.util
import usb.backend.libusb1

from infi.devicemanager import DeviceManager

dm = DeviceManager()
devices = dm.all_devices
for d in devices:
    try:
        print(f'{d.friendly_name} : address: {d.address}, bus: {d.bus_number}, location: {d.location}')
    except Exception:
        pass


backend = usb.backend.libusb1.get_backend(find_library=lambda x: "C:\\libusb-1.0.20\\MS32\\dll\\libusb-1.0.dll")
usb_devices = usb.core.find(backend=backend, find_all=True)


def enumerate_usb():  # I use a simple function that scans all known USB connections and saves their info in the file
    with open("EnumerateUSBLog.txt", "w") as wf:
        for i, d in enumerate(usb_devices):
            try:
                wf.write(f"USB Device number {i}:\n")
                wf.write(d._get_full_descriptor_str() + "\n")
                wf.write(d.get_active_configuration() + "\n")
                wf.write("\n")
            except NotImplementedError:
                wf.write(f"Device number {i} is busy.\n\n")
            except usb.core.USBError:
                wf.write(f"Device number {i} is either disconnected or not found.\n\n")

I had the same problem with Windows 10, both Python 2.7.16 and Python 3.7.2. I installed libusb (through python -m pip install libusb ) but the error message remained. Also, the advice above about installing libusb-win32 did not work for me; neither of the 2 links (original post and @beebek’s answer) existed.

What did work, however, is the comment by @user1495323 : I copied libusb-1.0.dll from
C:\Users\username\AppData\Roaming\Python\Python27\site-packages\libusb\_platform\_windows\x64\
to C:\Windows\System32\

1. download the latest libusb
   Download libusb

Copy MS32\dll\libusb-1.0.dll to C:\Windows\SysWOW64

Copy MS64\dll\libusb-1.0.dll to C:\Windows\System32

3.

pip install libusb

Copy MS32\dll\libusb-1.0.dll to C:\Python\Python37-32\Lib\site-packages\libusb_platform_windows\x86

Copy MS64\dll\libusb-1.0.dll to C:\Python\Python37-32\Lib\site-packages\libusb_platform_windows\x64

This method works for me.

answered Jun 26, 2020 at 2:32

answered Jan 14, 2022 at 12:01

LiviuLiviu

1,8592 gold badges22 silver badges48 bronze badges

answered Mar 15, 2015 at 9:15

This is a mix from multiple answers and here a ready-to-use solution for Windows x64 bit:

• Run:

  pip install pyusb
  pip install libusb
  

• Do:

  import usb.backend.libusb1
  backend = usb.backend.libusb1.get_backend(find_library=lambda x: r"C:\Python38\Lib\site-packages\libusb\_platform\_windows\x64\libusb-1.0.dll")  # adapt to your path
  usb_devices = usb.core.find(backend=backend, find_all=True)
  for usb_device in usb_devices:
      print(usb_device)
  

Done!

answered Sep 6 at 14:39

wovano

4,5725 gold badges22 silver badges50 bronze badges

I had a similar issue recently trying to talk to a USB device I am developing. I scoured the web looking for libusb-1.0.dll’s and had no luck. I found source code, but nothing built and ready to install. I ended up installing the libusb-win32 binaries, which is the libusb0.dll.

PyUSB will search for libusb-1.0, libusb0, and openUSB backends.

libusb0.dll was already on my system, but something was still not set up right, do PyUSB was not working.

I followed the directions here to download and install the driver using the GUI tools provided to install the filter driver, and the INF wizard. Note, it didn’t work until I ran the INF wizard.

I’m pretty new to programming and I’ve found the lack of clear documentation/examples to string this all together rather frustrating.

answered Dec 26, 2012 at 22:04

2021 and the problem still occurs on Windows (Windows 10). I solved it by installing pyusb and libusb and adding libusb path to Windows environment:

1. pip install pyusb
2. pip install libusb
3. libusb-1.0.dll will be automatically added to:

\venv\Lib\site-packages\libusb\_platform\_windows\x64
and
\venv\Lib\site-packages\libusb\_platform\_windows\x32

1. Now just add those paths (the full path) to Windows Path and restart CMD / PyCharm.

answered Jun 21, 2021 at 7:56

I am using Python 2.6.5, libusb-win32-device.bin-0.1.12.1 and pyusb-1.0.0-a0 on a windows XP system and kept receiving ValueError: No backend available.

Since there wasn’t any real help on the web for this problem I spent a lot of time finding that ctypes util.py uses the Path variable to find the library file. My path did not include windows\system32 and PYUSB didn’t find the library. I updated the path variable and now the USB is working.

There’s a simpler solution.

Download and unpack to C:\PATH the libusb-1.0.20 from download link

Then try this line:

backend = usb.backend.libusb1.get_backend(find_library=lambda x: "C:\\PATH\\libusb-1.0.20\\MS32\\dll\\libusb-1.0.dll")
usb_devices = usb.core.find(backend=backend, find_all=True)

Depending on your system, try either MS64 or MS32 version of the .dll

import usb.core
import usb.util
import usb.backend.libusb1

from infi.devicemanager import DeviceManager

dm = DeviceManager()
devices = dm.all_devices
for d in devices:
    try:
        print(f'{d.friendly_name} : address: {d.address}, bus: {d.bus_number}, location: {d.location}')
    except Exception:
        pass


backend = usb.backend.libusb1.get_backend(find_library=lambda x: "C:\\libusb-1.0.20\\MS32\\dll\\libusb-1.0.dll")
usb_devices = usb.core.find(backend=backend, find_all=True)


def enumerate_usb():  # I use a simple function that scans all known USB connections and saves their info in the file
    with open("EnumerateUSBLog.txt", "w") as wf:
        for i, d in enumerate(usb_devices):
            try:
                wf.write(f"USB Device number {i}:\n")
                wf.write(d._get_full_descriptor_str() + "\n")
                wf.write(d.get_active_configuration() + "\n")
                wf.write("\n")
            except NotImplementedError:
                wf.write(f"Device number {i} is busy.\n\n")
            except usb.core.USBError:
                wf.write(f"Device number {i} is either disconnected or not found.\n\n")

I had the same problem with Windows 10, both Python 2.7.16 and Python 3.7.2. I installed libusb (through python -m pip install libusb ) but the error message remained. Also, the advice above about installing libusb-win32 did not work for me; neither of the 2 links (original post and @beebek’s answer) existed.

What did work, however, is the comment by @user1495323 : I copied libusb-1.0.dll from
C:\Users\username\AppData\Roaming\Python\Python27\site-packages\libusb\_platform\_windows\x64\
to C:\Windows\System32\

1. download the latest libusb
   Download libusb

Copy MS32\dll\libusb-1.0.dll to C:\Windows\SysWOW64

Copy MS64\dll\libusb-1.0.dll to C:\Windows\System32

3.

pip install libusb

Copy MS32\dll\libusb-1.0.dll to C:\Python\Python37-32\Lib\site-packages\libusb_platform_windows\x86

Copy MS64\dll\libusb-1.0.dll to C:\Python\Python37-32\Lib\site-packages\libusb_platform_windows\x64

This method works for me.

answered Jun 26, 2020 at 2:32

answered Jan 14, 2022 at 12:01

LiviuLiviu

1,8592 gold badges22 silver badges48 bronze badges

answered Mar 15, 2015 at 9:15

This is a mix from multiple answers and here a ready-to-use solution for Windows x64 bit:

• Run:

  pip install pyusb
  pip install libusb
  

• Do:

  import usb.backend.libusb1
  backend = usb.backend.libusb1.get_backend(find_library=lambda x: r"C:\Python38\Lib\site-packages\libusb\_platform\_windows\x64\libusb-1.0.dll")  # adapt to your path
  usb_devices = usb.core.find(backend=backend, find_all=True)
  for usb_device in usb_devices:
      print(usb_device)
  

Done!

answered Sep 6 at 14:39