[PD] [PD-announce] hidraw v0.1.0 released.
Albert Rafetseder
albert.rafetseder at univie.ac.at
Tue Nov 8 12:26:27 CET 2022
>> Just tested hidraw on my linux laptop (latest deken version)
>>
>> Strangely, when I click [listdevice( message in help file, i get in
>> console the same device listed 14 times :
(...)
> I've seen some same devices appear 2, 3 or 4 times. Not sure why is
> this happening but is related to https://github.com/libusb/hidapi. I
> just use their function to list devices.
This should be fine. Indeed, ...
> eventually you can check that "Usage (page):" is different in each
> dup. not sure what this means or how to use it.
Some explanatory snippets:
"""Usages are part of the HID Report descriptor and supply an
application developer with information about what a control is actually
measuring or reporting.""" (from
https://www.usb.org/sites/default/files/hut1_3_0.pdf )
"""HID devices exchange data with the host computer using data bundles
called “reports”. Each report is divided into “fields”, each of which
can have one or more “usages”. In the hid-core, each one of these usages
has a single signed 32 bit value.""" (from
https://www.kernel.org/doc/html/v5.6/hid/hiddev.html#the-hiddev-api )
E.g., [hidraw] shows two entries for my USB mouse, with:
* Usage (page): 0x2 (0x1), making it a "Mouse" from the "Generic Desktop
Page".
* Usage (page): 0x1 (0x1), making it also a "Pointer" from the same Page
(My laptop's touchpad produces a dozen or so list entries as well. It's
a Mouse, a Pointer, a Digitzer for Fingers, and Vendor-Defined ... :-)
By the way, Linux's `lsusb -v` shows similar information to
[listdevices(--[hidraw]
Best regards,
Albert.
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