Has anyone attempted to add a serial I/O port to the ybox2? I'm new to electronics and such, and bought the ybox2 off of ThinkGeek mainly because I wanted a real-world device that I could gain more experience with. I've decided I'd like to work with the Parallax Propeller chip for an independent study I'm doing over the summer where I'll be controlling some Pioneer robots, which communicate via a serial port. Would the I/O port be too great an undertaking, or is it doable with this board (I understand that this would most likely involve a secondary board to tie everything into)?
I also just came across the Propeller Professional Development Board which appears to have a serial I/O port, but I'm not sure if that's just for programming or if it's a fully-integrated serial port. If the port can be fully-utilized, I may consider investing in that and using this ybox2 for some experimentation elsewhere.
I'm open to any suggestions people may have.

