This example generates fixed time interval pulses into the trigger port of Extender and you can see in the last image how trigger pulses are represented in EmotivPRO.
Pictured below is an Arduino Uno connected to the trigger input cable.
Below is the code we used to test which had a 10% duty cycle. Output on pin 9 shared with the LED so you can see the pulses, input voltage was ~3.5V.
We modified the default blink application to use pin 9 and set the high delay give a 10% duty cycle. 100ms High and 900ms low.
We saw the following output in EmotivPRO.