returnValues=PsychHID(subcommand, arg1 [,arg2] …)

OSX, Linux, Windows with GNU/Octave or Matlab version R2007a and later:

PsychHID is a MEX file that communicates with any USB device that
is HID-compliant. The Universal Serial Bus (USB) is quite popular, and
there are many USB devices that conform to the Human Interface Device
(HID) class. Typical HID devices are keyboards, mice and joysticks. That
is what the HID class was designed for, but manufacturers of more exotic
input and output devices, including audio breakout boxes and data
acquisition devices, have also opted to be HID-compliant.

In the OS9 and Win Psychtoolbox, most functions that accept user input
were implemented as device-specific mex files. In the OSX Psychtoolbox
they are M files that all call PsychHID, just one MEX for the many kinds
of input device. For example, in the OSX Psychtoolbox, Gamepad (formerly
named “Joystick”) and KbCheck are M functions that call PsychHID. For
user programs, it is easier to call these special-purpose functions (with
self-documenting names), which call PsychHID, than to call PsychHID
directly. PsychHID is more general, but also more complicated. However,
if you acquire a novel input/output device that is HID-compliant, you can
access it through PsychHID. PsychHID can distinguish between multiple
devices of the same type by their serialNumber or locationID.

NOT RESPONDING? If PsychHID is not responding, try quitting and
restarting MATLAB. We find that this reliably restores normal

MS-Windows and GNU/Linux: PsychHID uses the free/open-source libusb-1.0
library ( as a backend for low-level device control.
libusb is licensed under LGPLv2+ license. PsychHID also uses the BSD
licensed HIDAPI library ( as backend
for USB-HID access.

On Linux and Windows, not all PsychHID subfunctions are implemented, as
certain functionality can be handled in a better or different way on
those systems. USB-HID low-level access, and USB low-level access is
implemented though.

MS-Windows: You must manually install the libusb-1.0.dll library on your
system to use PsychHID. A working version is contained in the
Psychtoolbox/PsychContributed folder. More recent versions may be
downloaded from the official project website:

HELP: Like Screen, PsychHID has built-in help. For a list of PsychHID
subcommands enter “PsychHID” at the MATLAB command line:

>> PsychHID

For help on a specific PsychHID subcommand, call PsychHID with the
subcommand suffixed with a question mark, for example:

>> PsychHID NumDevices?
Return the the number of USB HID devices connected to your computer.

PsychHIDTest shows a list of all the HID-compliant devices.

PsychHID on OS/X links against Apples HID Utilities library. For information on
how to program HID devices on OS X in C or Objective C see the HID
utilities project, its companion project, HID Explorer and related:

OS9 & Windows with Matlab versions older than R2007a: ___________________

PsychHID does not exist in these Psychtoolboxes. The OS9 and
WIN Psychtoolbox functions that read from user input devices use mex
files specific to each input device.

See also: PsychHIDTest, Daq, DaqTest, KbCheck, Gamepad, PsychHardware.
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