Projecting with Arduino and Processing

Hey guys,

For a little project we want do project different videos and sounds to a screen. We have a working Processing Code for that which uses the Key pressed method to choose between the different sequences.

Now our idea was to transport the code into Arduino so we can have a user to choose the sequence. We wanted to use a Trimpot switch for that (one of those that you turn with a screwdriver) but I am not sure if that can be used in that way and how exactly i need to change my code. We are all totally new to Arduino, so every help for this would be awesome.