Patent ID: 8525685

Claim:
An apparatus for controlling a device having a touch sensor, comprising: a piezo transducer for detecting a pressure pattern applied to the sensor; a comparator coupled to the transducer; and a pressure pattern recognition circuit coupled to a comparator output of the comparator, the circuit being configured to: determine whether the pressure pattern satisfies a predetermined condition; and in response to the pressure pattern satisfying the predetermined condition, generate an output signal; a switch coupled to and selectively connecting the transducer to one of (i) a logic circuit and (ii) an oscillator, wherein: the transducer operates as a pressure pattern detector in response to being connected to the logic circuit, wherein the logic circuit provides a signal value corresponding to a logic value, thereby grounding a bottom lead of the transducer; and the oscillator provides an oscillating signal, thereby increasing a drive voltage to the transducer; and the transducer operates as an alarm generator in response to being connected to the oscillator; an inverter connected between the switch and a bottom lead of the transducer, wherein: the inverter is configured to transmit a ground signal to the transducer to permit the transducer to operate as the pressure pattern detector; and the inverter is configured to transmit an oscillating signal to the transducer to permit the transducer to operate as the alarm generator; a tri-state buffer coupled to a top lead of the transducer, wherein: in response to the tri-state buffer being set to a high impedance state, the transducer is permitted to operate as the pressure pattern detector; and in response to the tri-state buffer being set to a low impedance state, the transducer is permitted to operate as the alarm generator.