What sort of interface do you mean? Connect to PC?
No, I need to connect the board to a breadboard, where I'll shift the logic levels to 5v, so that I can connect them to different DIP chips, or an Arduino Uno. If you know of a good way of converting the logic levels in both ways, or of a good inexpensive converter, that'd be very helpful too. The thing should be capable of running at about 1-2 MHz.