Currently, it is not permitted to connect Arduino directly to the NXT in FTC. The alternative, the HiTechnic Prototype Board, does not support I2C functionality. With the Arduino connected to the HiTechnic Prototype Board instead of directly to the NXT, it cannot communicate using I2C with the NXT. This makes using the Arduino very inconvenient. What is the reason teams are not allowed to connect Arduino directly to NXT?
This link explains how people can connect Arduino directly to the NXT:
http://www.dexterindustries.com/howt...orms-together/