Difference between revisions of "Vertical Sync sensor"

TEMT6000 Licht Sensor Module
	TEMT6000 Licht Sensor Module
Downloads
	Datasheet;

Seeed Studio XIAO SAMD21
	Seeed Studio XIAO SAMD21
Downloads
	product_page;

Latest revision as of 11:42, 23 January 2023

The Vertical Sync sensor is used on a computer/laptop monitor for time accurate visual presentation. The sensor measures screen brightness. It generates a BITSI trigger to the com-port("A" = ON/light, "a" = OFF/noLight) when the amount of light is higher than the (customizable) threshold. This means that the onset of visual stimulus on screen can be marked. It can easily be attached with a pincher to the screen. The Vertical Sync sensor is connected to a computer with a usb connection, a serial port is emulated. You may want to read about presentation modes in order to decide how to use the sync sensor.

BITSI Protocol

BITSI stands for Bits to Serial Interface.

Vertical Sync sensor
ASCII (rise/fall)	Code (rise/fall)	Light
A / a	65 / 97	ON / OFF

Meaning when light falls on the sensor, a capital A will be sent to the serial port. A lowercase 'a' will be sent when the signal is deactivated(no light).

Output

The treshold for monitor OFF is customizable and can be specified by sending a byte to specify the value for screen OFF. Any byte satisfies, see example code.

Port Settings

Serial port

Our hardware design allows to be connected to the computers USB and emulates a serial communication Port.

Baudrate	115200
Parity	None
Data bits	8
Stop bits	1
Flow control	None

USB-Com port

1.Connect the Vertical Sync sensor to your computer using the USB cable.

2.When you connect the Vertical Sync sensor, Windows should initiate the driver installation process (if you haven't used the computer with an Vertical Sync sensor before).

How to Check the Com Port settings(important!)

From the Start menu, open the Control Panel.

From the control panel, open the System window.

From the system properties window, go to the Hardware tab and click the Device Manager button.

From the Device Manager window, click Ports (Com&LPT). You should now be able to see which Com Port the USB adapter is assigned to.

If the Com Port is 10 or higher, you will have to change it to a lower port.

From the Device Manager window, click on USB Serial Port (Com#). Click the Port Settings tab of the USB Serial Port Properties window, and then click the Advanced button.

In the Advanced Settings window, use the scroll input to select a Com Port (select 10 or lower). Change Receive (bytes) and Transmit (bytes) to 64. Change the Latency Timer to 1.

Click the OK button.

Always connect the usb device to the same port and your settings will be remembered.

Software Settings

Python/PsychoPy

The basics using the Vertical Sync sensor in PsychoPy:

1# initialize treshold for OFF by sending a code
2ser.write(b'1')
3
4visual.Rect(win, .15, .25, pos=(-1, 1),fillColor="white", units="norm").draw()
5win.flip()
6# wait for a sync square
7b = ser.read()

Example script using the Vertical Sync sensor in PsychoPy:

 1#!/usr/bin/env python
 2
 3# import psychopy and rusocsci
 4from psychopy import core, visual 
 5import serial
 6import time
 7
 8## Setup Section
 9win = visual.Window([400,400], fullscr=True, winType = "pyglet", monitor="testMonitor",color=(-1, -1, -1), waitBlanking=True)
10# connect to Vertical Sync sensor, find correct com port number
11ser = serial.Serial('com3', 115200, timeout=1.0)
12# create sync box left corner
13rect = visual.Rect(win, .15, .25, pos=(-1, 1),fillColor="white", units="norm")
14
15# wait 5 sec for python to become stabel
16core.wait(5)
17ser.flushInput()
18# define screen OFF by sending a code
19ser.write(b'1')
20
21## Experiment Section
22# show sync box left corner
23rect.draw()
24win.flip()
25tik = time.perf_counter()
26# wait for a sync square
27b = ser.read()
28tok = time.perf_counter()
29# show delay after a flip
30print("your timing after a flip: {}s".format(tok-tik))
31# as a remark 60Hz/~0.016s 120Hz/~0.008s
32
33## Cleanup Section
34core.quit()

Matlab

Example using markers with the Buttonbox in Matlab:

Download the file Bitsi.m from the DCCN website: https://intranet.donders.ru.nl/index.php?id=bitsim0
Make sure to have this file in your Matlab path.

1% At the start of your script, create the buttonbox serial object
2bb = Bitsi("COM2");
3% other code
4        :

BITSI simple mode:

 1% This example is for an EEG system sampling at 500Hz samplerate.  
 2% at the start of your script, reset marker
 3samplerate = 500;
 4pulseLen = 2000/samplerate;
 5bb.sendTrigger(0);
 6% send a marker
 7val = 1;                                     % val: this is your marker code, range code 1-255
 8bb.sendTrigger(val);
 9java.lang.Thread.sleep(pulseLen);    % wait long enough for the EEG system to capture the trigger, i.e., 2000/samplerate ms
10% reset marker
11bb.sendTrigger(0)                 % Note: if resetting the marker is not possible at this moment in code, you can decide to do this later as long as it has taken place long enough before the next marker has to be sent.

@@ Line 1: / Line 1: @@
+{{Infobox tsg
+| name           = Vertical Sync sensor
+| image          = sensorPic.jpg
+| caption        = Vertical Sync sensor
+}}
 {{Infobox tsg
 | name           = Seeed Studio XIAO SAMD21
@@ Line 9: / Line 14: @@
 {{Infobox tsg
 | name           = TEMT6000 Licht Sensor Module
-| image          = https://surfdrive.surf.nl/files/index.php/s/2Fi3tG8UD1zIqto
+| image          = temt6000.jpg
 | caption        = TEMT6000 Licht Sensor Module
 | downloads      = {{bulleted list
@@ Line 16: / Line 21: @@
 }}
-The Vertical Sync sensor is used on a computer/laptop monitor for time accurate visual presentation. The sensor measures screen brightness. It generates a BITSI trigger("A" = ON/light, "a" = OFF/noLight) when the amount of light is higher than the (customizable) threshold, which means that the exact onset of any visual stimulus can be marked. It can easily be attached to any screen with a pincher. The Vertical Sync sensor is connected to a computer with a usb connection.
+The Vertical Sync sensor is used on a computer/laptop monitor for time accurate visual presentation. The sensor measures screen brightness. It generates a BITSI trigger to the com-port("A" = ON/light, "a" = OFF/noLight) when the amount of light is higher than the (customizable) threshold. This means that the onset of visual stimulus on screen can be marked. It can easily be attached with a pincher to the screen. The Vertical Sync sensor is connected to a computer with a usb connection, a serial port is emulated. You may want to read about [[presentation modes]] in order to decide how to use the sync sensor.
 == BITSI Protocol ==
@@ Line 33: / Line 38: @@
 |}
-This means that when light falls on the sensor, a capital A will be sent to the serial port. A lowercase 'a' will be sent when the signal is deactivated(no light).
+Meaning when light falls on the sensor, a capital A will be sent to the serial port. A lowercase 'a' will be sent when the signal is deactivated(no light).
 ===Output===
-The treshold for OFF is customizable and can be specified by sending a code Send code to specify the value for screen OFF.
+The treshold for monitor OFF is customizable and can be specified by sending a byte to specify the value for screen OFF. Any byte satisfies, see example code.
-EDIT howto
 == Port Settings ==
@@ Line 89: / Line 92: @@
 == Software Settings ==
-=== Neurobs Presentation ===
+=== Python/PsychoPy ===
-The experiment files needs a few settings for the device to work:
+<br/>'''The basics using the Vertical Sync sensor in PsychoPy:'''
-* In the settings tab:  port -> input port -> 1 must be the device that identifies itself as "Arduino Uno" in the device manager. Note that the port must have a number not higher than 10 (COM1-COM10). Use re-enumerate if it is higher.
-* Rate must be set 115200, Parity to None, Data Bits to 8 and Stop Bits to 1, Uncheck FIFO Interrupt.
-[[File:Buttonbox2.png]]
+<syntaxhighlight lang="python" line>
+# initialize treshold for OFF by sending a code
+ser.write(b'1')
-'''Adding Marker'''
+visual.Rect(win, .15, .25, pos=(-1, 1),fillColor="white", units="norm").draw()
+win.flip()
+# wait for a sync square
+b = ser.read()
+</syntaxhighlight>
-[[file:output_buttonbox1.png | 800px]]
+<br/>'''Example script using the Vertical Sync sensor in PsychoPy:'''
-'''Example PCL code you can program a handle to send a marker:'''
- #handle:
- output_port OutputPort = output_port_manager.get_port( 1 );
-'''Example to send a treshold callibration:'''
- OutputPort.send_code(100); #create a marker
-=== Python/PsychoPy ===
-<br/>'''Example using the Vertical Sync sensor in PsychoPy:'''
 <syntaxhighlight lang="python" line>
@@ Line 122: / Line 117: @@
 ## Setup Section
-win = visual.Window([400,400], fullscr=True, winType = "pyglet", monitor="testMonitor",color=(-1, -1, -1), units='cm',
+win = visual.Window([400,400], fullscr=True, winType = "pyglet", monitor="testMonitor",color=(-1, -1, -1), waitBlanking=True)
-	waitBlanking=True)
+# connect to Vertical Sync sensor, find correct com port number
-# connect to Vertical Sync sensor, find com port number
 ser = serial.Serial('com3', 115200, timeout=1.0)
+# create sync box left corner
 rect = visual.Rect(win, .15, .25, pos=(-1, 1),fillColor="white", units="norm")
-# define treshold for OFF by sending a code
+# wait 5 sec for python to become stabel
+core.wait(5)
+ser.flushInput()
+# define screen OFF by sending a code
 ser.write(b'1')
 ## Experiment Section
-# show text
+# show sync box left corner
 rect.draw()
 win.flip()
-tok = time.perf_counter()
+tik = time.perf_counter()
 # wait for a sync square
 b = ser.read()
-tik = time.perf_counter()
+tok = time.perf_counter()
-# show result, 60Hz/~0.016s 120Hx/~0.008s
+# show delay after a flip
-print("your timing: {}s".format(tik-tok))
+print("your timing after a flip: {}s".format(tok-tik))
+# as a remark 60Hz/~0.016s 120Hz/~0.008s
 ## Cleanup Section