A rearview mirror system for a vehicle includes an interior rearview mirror assembly including a control. The interior rearview mirror assembly may include a video display device operable to display video information for viewing by a driver of the equipped vehicle through an electrochromic reflective element of the interior rearview mirror assembly. The control may include a digital signal processor disposed in the interior rearview mirror assembly. The interior rearview mirror assembly may include a vehicle bus node. When the interior rearview mirror assembly is mounted in the equipped vehicle, the vehicle bus node may be connected to a vehicle bus of the equipped vehicle, and at least one of (a) the control conveys signals to the vehicle bus via the vehicle bus node and (b) the vehicle bus conveys signals to the control via the vehicle bus node.