HID Input Element

Summary ¶

	HID Input
Info
Category:	Input Registration		AddIn:	Base Layer
Creator:	OkazoLab		Scope:	Parent event
Owns Snippets:	None		Usage:	Snippets

Properties ¶

Name	Description	Constraints	Type	On runtime change
Settings
HID Device	Selected HID device	Design Time..	String
Axis Scaling	Defines whether the physical axis values are automatically scaled into the device's defined logical range. If false, the physical axis values are returned.	Normal..	Boolean
Triggering Mode	Defines the triggering mode for button. The 'First Press Only' mode is recommended for response time measurements	Design Time..	enButt..
Monitored Button	Defines a button monitored by the element. If 'Any Button' selected, the element monitors all buttons on the selected input device. In this case, a name of the pressed button is indicated by the Triggering Button property at runtime.	Design Time..	Int32
Device Info
Button Number	Number of buttons on the selected HID device	Status..	Int32
Axis Number	Number of analog axis on the selected HID device	Status..	Int32
Runtime Status
Raw Input	Returns the HID data string contains the newest raw input in HEX format. You can use this value for decoding data of non-standard HID devices	Status..	String
Axis Values	Returns an integer array of current values of the device's analog axis. The length of the array is always equal to the number of analog axis on the selected device. You can open the associated analog axis monitor to see what axis corresponds to each of the array indices.	Status..	Int32[]
Triggering Time	Returns a local event time (in ms) of the last button triggering. The value can be used an accurate measure of the response time	Status..	clTime
Is Triggered	Indicates whether a button has been triggered at least once, since the onset of the parent event. This property can be naturally used to gate switching between events.	Normal..	Boolean
Triggered Button	Returns a system name of the triggered button. The keyboard symbol buttons are always shows by the capital letters, whereas the mouse and gamepad buttons are shown by names like 'Button 1'	Status..	String
Is Down	Indicates whether the monitored button is currently in the down state	Normal..	Boolean
colspan="5" bgcolor="#AADDDDD" |
		Normal..	Boolean
		Normal..	Boolean
Control
Is Enabled	If set to false the element is completely omitted when the experiment is run	Design Time..	Boolean
Title	Title of the element	Design Time..	String

¶

Description ¶

Selecting the monitored button ¶

1. Create two button elements, each monitoring one of the predefined response buttons
2. Create one button element monitoring 'Any' button and write a code that checks, what button is pressed. The name of the pressed button is returned by the Triggered Button property
   

Selecting the triggering modes for buttons ¶

• First Press Only
• First Release Only
• Multiple Presses
• Multiple Releases
• Holding Down
  

HID Button Names ¶

Using the press detector to set the monitored button or find out the button name

Triggered Snippet ¶

if (TriggeringButton=="NumPad4")
Positon.X=PositionX-1;
if (TriggeringButton=="NumPad6")
Positon.X=PositionX+1;

Monitoring the analog axis ¶

Checking the analog axis of the HID device

Practical Use ¶

Implementing the "Press any button to continue" design pattern ¶

1. Add the button element to the 'stop' event
2. Browse the button element properties in the property panel
3. Select the Input Device, for example, a keyboard
4. Leave Triggering Mode and Monitored Button with the default values, 'First Press Only' and 'Any Button'
5. Create a proxy variable linked to the Is Triggered property of the element
6. Go back to the parent event and add the conditional flow route leading to a successive event.
7. Write an expression for the conditional route as (IsTriggered==true), where the first part is a name of the proxy variable linked to the button element
   

Implementing the reaction time measurement with a single button ¶

1. Add the button element to the 'measurement' event, normally one where the stimulus is presented
2. Browse the button element properties in the Properties panel
3. Select the Input Device, for example, a keyboard
4. Leave Triggering Mode with the default value, 'First Press Only'
5. Select Monitored Button
6. Create a proxy variable linked to the Is Triggered property of the element
7. Create a proxy variable linked to the Triggering Time property
8. Go back to the parent event and add the conditional flow route leading to a successive event, if you want to terminate the event on a button press.
9. Write an expression for the conditional route as (IsTriggered==true), where the first part is a name of the proxy variable linked to the Is Triggered property
10. After offset of the 'measurement' event, pick up the value of the Triggering Time proxy variable. For example, you can save it to the data report via the Reporter Element
    

Recording times of multiple button presses within a single event ¶

1. Add the button element to the 'measurement' event, normally one where the stimulus is presented
2. Browse the button element properties in the Properties panel
3. Select the Input Device, for example, a keyboard
4. Set Triggering Mode to 'Multiple presses'
5. Select Monitored Button
6. Create a proxy variable linked to the Triggering Time property
7. Open the triggered snippet of the button element via the snippet panel
8. Add the following code to the snippet. The code adds a time of the current button press to a dedicated array list.
   

/// PressTime is a list declared in the header, e.g.
/// ArrayList PressTimes=new ArrayList();

PressTimes.Add(TriggeringTime);

Moving a visual marker by HID joystick ¶

1. Add the HID Input element to the event, in what the marker is presented
2. Browse the HID Input element properties in the Properties panel
3. Select your joystick via the Input Device property
4. Expand Analog Axis property and move joystick in the extreme positions in each direction
5. Find the axis indices that corresponds to the stick control. Write down the minimal and maximal values on these axis.
6. Create a proxy variable linked to the Analog Axis property
7. Add the Renderer element with any marker shape and create a proxy variable linked to Renderer's Position property
8. Add the following code to the Control Loop snippet of the parent event. The code will update the marker position based on the current joystick axis values.
   

/// Define the actual limits of each axis
/// empirically measured in the '''Axis Values''' editor
double MinX=0;
double MaxX=255;
double MinY=0;
double MaxY=255;

/// Updating the position of the visual marker in the normalized screen coordinates
Position.CX=(AxisValues[1]-MinX)/(MaxX-MinX)-0.5;
Position.CY=(AxisValues[0]-MinY)/(MaxY-MinY)-0.5;

Notes ¶

• If the monitored button is already pressed on the event onset, the element is not triggered by press immediately, it happens only on the next press. However, you can use the Is Down property, which identifies a state of the monitored button at any moment.
• The Triggering Time, Is Triggered and Triggered Button properties are nullified on the onset of the parent event. However, you can read these values in other events after the offset of the parent event
• Is Down property can be used a button state flag, independently of the selected triggering mode