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{{Infobox tsg
| name = Vertical Sync sensor
| image = sensorPic.jpg
| caption = Vertical Sync sensor
}}
{{Infobox tsg
{{Infobox tsg
| name = Seeed Studio XIAO SAMD21
| name = Seeed Studio XIAO SAMD21
}}
}}
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 ==
== BITSI Protocol ==
|}
|}
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===
===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.
== Port Settings ==
== Port Settings ==
=== Python/PsychoPy ===
=== Python/PsychoPy ===
<br/>'''Example using the Vertical Sync sensor in PsychoPy:'''
<br/>'''The basics using the Vertical Sync sensor in PsychoPy:'''
<syntaxhighlight lang="python" line>
# initialize treshold for OFF by sending a code
ser.write(b'1')
visual.Rect(win, .15, .25, pos=(-1, 1),fillColor="white", units="norm").draw()
win.flip()
# wait for a sync square
b = ser.read()
</syntaxhighlight>
<br/>'''Example script using the Vertical Sync sensor in PsychoPy:'''
<syntaxhighlight lang="python" line>
<syntaxhighlight lang="python" line>
## Setup Section
## Setup Section
win = visual.Window([400,400], fullscr=True, winType = "pyglet", monitor="testMonitor",color=(-1, -1, -1), waitBlanking=True)
win = visual.Window([400,400], fullscr=True, winType = "pyglet", monitor="testMonitor",color=(-1, -1, -1), waitBlanking=True)
# connect to Vertical Sync sensor, find com port number
# connect to Vertical Sync sensor, find correct com port number
ser = serial.Serial('com3', 115200, timeout=1.0)
ser = serial.Serial('com3', 115200, timeout=1.0)
# create sync box left corner
# create sync box left corner
rect = visual.Rect(win, .15, .25, pos=(-1, 1),fillColor="white", units="norm")
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')
ser.write(b'1')
rect.draw()
rect.draw()
win.flip()
win.flip()
tik = time.perf_counter()
# wait for a sync square
# wait for a sync square
b = ser.read()
b = ser.read()
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
## Cleanup Section