Sorry for the long post ahead. I'm working on a project involving structured light, and I am using the Arduino to grab a timing signal from a DLP projector, using the interrupt function on the Arduino. The signal on the projector jumps between 0V and 3.3V. I originally the signal from the projector connected directly into an Arduino pin, and I ended up damaging the IC on the projector. Some of the issues I noticed include:
-when I plug in the Arduino USB to power it on, the projector will flash and turn off -when I physically touch the connecting wire, the colors of the projector's colors will be unstable.
I'm guessing the issue is from voltage surges when turning on the Arduino (?), I am wondering how I can prevent damage in the future. Some things I've looked into include adding a resistor in series and using a TVS diode, but I can't find much information on how to use these TVS diodes properly. Will the simple circuit shown here http://www.semtech.com/images/promo/What_are_TVS_Diodes.pdf work for my purposes? Would I just be choosing one with a breakdown voltage of 3.3V? Also, would I be using a bidirectional TVS diode, or would the one shown work? Lastly, I saw some circuits where the TVS diode was connected to a Vdd, such as
What difference does that make?
Thanks in advance everyone!