A system for controlling a string of lights, where each light or group of lights has a microcontroller for controlling their brightness and color. The light's microcontrollers are connected with serial data communication lines in a daisy chain fashion. Unique identification numbers are automatically assigned sequentially to each of the lights so brightness or color information transmitted on the serial data line is directed to a particular light. A plurality of brightness and color settings are stored on each light, and the string of lights synchronously switches between them on command from the serial line, or smoothly fades between them on command from the serial line.