Here’s a super easy to use way of connecting arduino controllers to grasshopper. Gets you a nice toolbar add on, includes the full sketches needed to run Arduino Uno and Mega so there is no need to know any coding for the Arduino Sketch. Just click and drag to upload and follow the instructions included.
I used this quite a bit for reading information from a microcontroller I made and a Wii Nunchuck. It also made it quite easy to program the RGB LEDs in my group’s final studio model.