using a USB HID device

[Wouter van Ooijen]

I want to use Python to interface with an USB HID device (not a
keyboard or mouse, just something that uses the HID driver to avoid
the need for a specific driver). Is this possible in pure Python on
Windows, or even better, in a portable way?

Wouter van Ooijen

-- ------------------------------------

http://www.voti.nl

PICmicro chips, programmers, consulting

[Martin v. Löwis]

Re: using a USB HID device

Wouter van Ooijen (www.voti.nl) wrote:[color=blue]
> I want to use Python to interface with an USB HID device (not a
> keyboard or mouse, just something that uses the HID driver to avoid
> the need for a specific driver). Is this possible in pure Python on
> Windows, or even better, in a portable way?[/color]

What is the Win32 API for such devices? If it is plain
CreateFile/ReadFile/WriteFile/DeviceIoControl , you should be
able to do it in pure Python, using the PythonWin extensions.

Likewise, on Unix, you can use device nodes, and the fcntl module.

I don't think there is a platform-independent Python module for
such devices, yet, but you could write your own abstraction layer
using those building blocks.

HTH,
Martin

[Samuel Schulenburg]

Re: using a USB HID device

wouter@voti.nl (Wouter van Ooijen (www.voti.nl)) wrote in message news:<40827ce3. 1151345337@news .xs4all.nl>...[color=blue]
> I want to use Python to interface with an USB HID device (not a
> keyboard or mouse, just something that uses the HID driver to avoid
> the need for a specific driver). Is this possible in pure Python on
> Windows, or even better, in a portable way?
>
> Wouter van Ooijen
>
> -- ------------------------------------
> http://www.voti.nl
> PICmicro chips, programmers, consulting[/color]

I have developed routines for Windows that address mass storage
devices using the Windows SCSIPASSTHROUGH layer. I found that USB
devices do not use this layer, and as a result I am also investigating
using python to access USB devices. So far it looks like a seperate
driver along with a interfaceing DLL will needed.

Sam Schulenburg

[Wouter van Ooijen]

Re: using a USB HID device

>> I want to use Python to interface with an USB HID device (not a[color=blue][color=green]
>> keyboard or mouse, just something that uses the HID driver to avoid
>> the need for a specific driver). Is this possible in pure Python on
>> Windows, or even better, in a portable way?[/color]
>
>What is the Win32 API for such devices?[/color]

To be honest, I don't have the faintest idea. I hoped there would be
some abstraction layer (freferrably a portable one) like for serial
ports.


Wouter van Ooijen

-- ------------------------------------

http://www.voti.nl

PICmicro chips, programmers, consulting

[Jeff Epler]

Re: using a USB HID device

libusb is portable to Linux, BSD including OS X, and Windows.
I don't know of a Python wrapper, however, and my experience using
libusb on windows is limited.

http://libusb.sf.net

http://libusb-win32.sf.net/

For my own application, I wrote my device's API in C and wrapped it
using Pyrex.

Jeff

[Roger Binns]

Re: using a USB HID device

Samuel Schulenburg wrote:[color=blue]
> wouter@voti.nl (Wouter van Ooijen (www.voti.nl)) wrote in message news:<40827ce3. 1151345337@news .xs4all.nl>...[color=green]
> > I want to use Python to interface with an USB HID device (not a[/color]
>
> I found that USB
> devices do not use this layer, and as a result I am also investigating
> using python to access USB devices. So far it looks like a seperate
> driver along with a interfaceing DLL will needed.[/color]

Here is one I made earlier:

http://cvs.sf.net/viewcvs.py/bitpim/bitpim/native/usb/

It is a Python wrapper (using SWIG) around libusb (including libusb-win32).
My BitPim project currently ships using it on Windows, Linux and Mac.

Roger

[Martin v. Löwis]

Re: using a USB HID device

Jeff Epler wrote:[color=blue]
> libusb is portable to Linux, BSD including OS X, and Windows.
> I don't know of a Python wrapper, however, and my experience using
> libusb on windows is limited.
>
> http://libusb.sf.net
> http://libusb-win32.sf.net/[/color]

It looks like libusb, on Windows, installs its own kernel driver,
which generates devices named \\.\libusb*. So this is not exactly
a pure-python solution :-)

OTOH, it may well be that USB devices, on Windows, cannot be
accessed purely from user mode, and that you always need some
sort of kernel driver.

Regards,
Martin

[Wouter van Ooijen]

Re: using a USB HID device

>OTOH, it may well be that USB devices, on Windows, cannot be[color=blue]
>accessed purely from user mode, and that you always need some
>sort of kernel driver.[/color]

But I can live with something that appears to be pure python, like one
which only requires a win-specific addition. after all win32all is
windows-specific too, but I regard it as part of the windows-python
installation. One more dll is no problem, as long as I don't have to
write (and maintain!) it :)



Wouter van Ooijen

-- ------------------------------------

http://www.voti.nl

PICmicro chips, programmers, consulting

[Martin v. Löwis]

Re: using a USB HID device

Wouter van Ooijen (www.voti.nl) wrote:[color=blue]
>
> But I can live with something that appears to be pure python, like one
> which only requires a win-specific addition. after all win32all is
> windows-specific too, but I regard it as part of the windows-python
> installation. One more dll is no problem, as long as I don't have to
> write (and maintain!) it :)[/color]

So libusb-win32 might be the solution for you (with other libusb
incarnations for other systems).

Notice, however, that your users need administrator privileges to
install a kernel mode driver.

Regards,
Martin

[Roger Binns]

Re: using a USB HID device

Martin v. Löwis wrote:[color=blue]
> Notice, however, that your users need administrator privileges to
> install a kernel mode driver.[/color]

Yup. However you can access a device if there is a device driver
attached as well, as long as it is not open. For example if you
have a USB to serial device, you can open it under libusb-win32
providing no other user space code has it open as a com port device.

Unfortunately with both Linux and Mac, libusb can only open devices
for which there is no driver currently attached (irrespective of
whether there is a user space program with the device open).

Windows also requires that a driver be present. There is a do
nothing driver included with libusb-win32 that can be used.

Roger

[Samuel Schulenburg]

Re: using a USB HID device

wouter@voti.nl (Wouter van Ooijen (www.voti.nl)) wrote in message news:<40827ce3. 1151345337@news .xs4all.nl>...[color=blue]
> I want to use Python to interface with an USB HID device (not a
> keyboard or mouse, just something that uses the HID driver to avoid
> the need for a specific driver). Is this possible in pure Python on
> Windows, or even better, in a portable way?
>
> Wouter van Ooijen
>
> -- ------------------------------------
> http://www.voti.nl
> PICmicro chips, programmers, consulting[/color]

I have been trying different approches to accessing mass storage
flash memory cards via the SCSIPASSTHROUGH layer under windows. I was
able to issue the reduced instruction scsi command set with a windows
DeviceIoControl () call. The main problem is finding information on how
Microsoft merged the usb mass storage interface to the scsi routines.

Sam Schulenburg