Window controller systems and methods are disclosed herein. In some embodiments, a window controller system for controlling multiple optically switchable devices comprises a printed circuit board comprising a first plurality of footprints to which a first plurality of components is mounted and a second plurality of footprints, wherein a subset of the second plurality of footprints is populated by a second plurality of components. The first plurality of components may comprise: a plurality of insulated glass unit (IGU) controllers, each configured to control an IGU of a corresponding plurality of IGUs operatively coupled to the window controller system; and a processing unit configured to control each of the plurality of IGU controllers. The second plurality of components may be selected based on a cable type and/or a protocol type used to provide power and data signals to the printed circuit board.