LVDS and Cyclone II Nios DEV Kit

Typically, LVDS I/O is used in combination with the SERDES (ALTLVDS) MegaFunction. If you only need LVDS receivers and transmitters for general I/O, nothing must be done except assigning an LVDS I/O standard to the pin.

Bidirectional LVDS is supported beginning with Cyclone III and Stratix III, but not available for Cyclone II, see the ALTIOBUF MegaFunction and AN522. With Cyclone II, two pin pairs would be needed to implement a similar function, one LVDS receiver pair and a pair of pseudo-differential operated tris-state buffers.

If you only need a tri-state differential driver, it's more easy.