[keyIsDown,secs,keyCode]=PsychHID(‘KbCheck’ [, deviceNumber][, scanList])
Scan a keyboard, keypad, or other HID device with buttons, and return a vector
of logical values indicating the state of each key.
By default the default keyboard device (as determined by some operating system
dependent heuristic) is scanned. If no keyboard is found, the first keypad
device is scanned, followed by other devices, e.g., mice. Optionally, the
‘deviceNumber’ of any keyboard or HID device may be specified.
As checking all potentially 256 keys on a HID device is a time consuming
process, which can easily take up to 1 msec on modern hardware, you can restrict
the scan to a subset of the 256 keys by providing the optional ‘scanList’
parameter: ‘scanList’ must be a vector of 256 doubles, where the i’th element
corresponds to the i’th key and a zero value means: Ignore this key during scan,
whereas a positive non-zero value means: Scan this key.
The PsychHID(‘KbCheck’) implements the KbCheck command as provided by the OS 9
Psychtoolbox. KbCheck is defined in Psychtoolbox-3 and invokes
PsychHID(‘KbCheck’). Always use KbCheck instead of directly calling
PsychHID(‘KbCheck’), unless you have very good reasons to do otherwise and
really know what you’re doing!