expyriment.io.extras.CedrusResponseDevice¶
- class expyriment.io.extras.CedrusResponseDevice(device_ID=0, error_screen=True)¶
A class implementing a Cedrus XID response device.
Notes
The CedrusResponseDevice class requires a free Python package for Cedrus devices called “pyxid”. For installation instructions see Expyriment online documentation:
The class does not use the hardware timer, due to the known bug in the Cedrus hardware. Events will be time stamped by Expyriment. Thus, ensure constant polling / checking when not using the wait function.
To install Cedrus resonse device under Linux, you have to set the USB product ID. To do so, edit the file /etc/modules and add the following line:
ftdi_sio vendor=0403 product=f228
Methods
- __init__(device_ID=0, error_screen=True)¶
Create a Cedrus Device Input.
Parameters : device_id : int, optional
device ID (default=0). Only required if more than one Cedrus Devices are connected.
error_screen : bool, optional
set False to switch off the ‘device not found’ error screen. An exception will be raise instead (default=True)
Notes
If no Cedrus device is connected, an error text screen will be presented informing that the device could not be found and suggesting to check the connection and to switch on the device. After keypress the class tries to reconnect with the device. Use <q> to quit this procedure.
- buffer¶
Getter for buffer.
- check(codes=None)¶
Check for a specific response code occurred since last clear().
The function polls the device and returns the first event found in the buffer (i.e., since last clear) or None.
Parameters : codes : int or list, optional
key codes to check for
Returns : key : int
code of pressed key
rt : int
reaction time in ms
- clear()¶
Clear device and all events in the response cues.
- id¶
Getter for XID device id.
- logging¶
Getter for logging.
- poll_responses()¶
Poll the Cedrus response device and copies the available response in the buffer.
Returns : out : bool
True is a new response was available.
Notes
Release key events get a code larger 999 (1000 + key code).
- set_logging(onoff)¶
Set logging of this object on or off
Parameters : onoff : bool
set logging on (True) or off (False)
Notes
See also design.experiment.set_log_level fur further information about event logging.
- wait(codes=None, duration=None, no_clear_buffer=False, check_for_control_keys=True)¶
Wait for responses defined as codes.
The functions returns the found key code and the reaction time, that is, the time relative to the called of wait. By default the buffer will be cleared() before waiting.
Parameters : codes : int or list, optional
codes to wait for
duration : int, optional
maximal time to wait in ms
no_clear_buffer : bool, optional
do not clear the buffer. In this case RT could be negative, if the event is already in the buffer (default = False)
check_for_control_keys : bool, optional
checks if control key has been pressed (default = True)
Returns : key : int
code of pressed key
rt : int
reaction time in ms
Notes
The function checks for control keys (quit and pause) by default. Thus, keyboard events will be cleared from the cue and cannot be received by a Keyboard().check() anymore!
- xid_interface¶
Getter for xid device interface.
