Abstract: Piezoelectric user interface arrangement comprises a voltage converter for controllably generating voltage waveforms driving one or more piezoelectric elements. The voltage converter has a control input. A controller is coupled to said control input to control an output voltage of said voltage converter. The controller has one or more scaling inputs. The controller forms said control signals to make said output voltage follow a target waveform as a function of time. The controller is configured to scale said target waveform on the basis of scaling information received through said one or more scaling inputs.

Abstract: Apparatus for a touch sensor, the apparatus comprising circuitry for processing signaling to determine the detection of touch input, wherein the circuitry for processing is arranged to detect touch input by comparing touch signaling with one or more reference thresholds, and wherein the circuitry for processing is arranged to perform a first touch calibration, following the detection of the first touch, to provide a first reference threshold which compensates for the signaling associated with the first touch, and wherein the circuitry for processing is arranged to detect a subsequent next touch, using the first reference threshold, as the reference threshold for detection of said next subsequent touch.