Changing the detection range of a touch sensor

In one embodiment, a controller includes a storage unit and a processor unit. The processor unit is coupled to the storage unit and configured to receive a signal associated with an operation of a device that includes a touch sensor. The touch sensor includes a first plurality of electrodes oriented in a first direction in a first portion of the touch sensor, a second plurality of electrodes oriented in the first direction in a second portion of the touch sensor, and a third plurality of electrodes intersecting the first and second plurality of electrodes. The processor unit is further configured to determine, in response to the signal, that a detection mode of the touch sensor is to be changed and in response to the determination, couple the second plurality of electrodes to a fixed voltage source to decrease a detection range in the second portion of the touch sensor.