You Reply: So the problem I am trying to solve is that when I do a digitalWrite(4, Arduino.HIGH) in my C# application, the pin does not always go high. For development and testing, I have an Arduino LEONARDO connected via USB to my Windows development machine. Occasionally when I try to set the pin high, I can see received data LED flicker slightly and the pin I am setting is supposed to trigger a relay on a relay board and the relay input LED flashes slightly but the relay does not latch. As a workaround (which shouldn't be needed), I had to do 3 digitalWrite(4, Arduino.HIGH) statements with a 200 ms delay between each to consistently latch my relay when needed.