RS-485 is used for DMX-512. I built a clone of the Open DMX USB interface a while back and the transceiver IC is indeed just the electrical interface between a USB serial UART and the DMX bus. You should be able to use the onboard UART in just about any modern microcontroller to talk RS-485. The dimmer packs I built are based on a variation of this AVR based circuit and use his code.

http://www.hoelscher-hi.de/hendrik/english/dimmer.htm