In one embodiment, a method comprises driving one or more drive electrodes formed on a substrate with one or more drive signals. A wiper comprising at least one arm is driven to a predetermined voltage. The wiper is electrically insulated from a plurality of sense electrodes formed on the substrate. For each sense electrode of the plurality of sense electrodes, a charge stored by the sense electrode is detected. A processor determines a position of the wiper based on the detected charges stored by the plurality of sense electrodes.