Abstract: Various embodiments are described herein for an asymmetrical bus keeper circuit that provides asymmetrical drive towards one logic level. The asymmetrical bus keeper circuit comprises a first inverter stage having an input node and an output node, an asymmetrical inverter stage having an input node and an output node and a feedback stage with an input node and an output node. The input node of the asymmetrical inverter stage is connected to the output node of the first inverter stage. The input node of the feedback stage connected to the output node of the asymmetrical inverter stage and the output node of the feedback stage connected to the input node of the first inverter stage. The asymmetrical stage provides asymmetrical drive towards one logic level.

Abstract: According to one aspect, an electronic device adapted to be controlled by an audio accessory. The electronic device includes at least one resonator. Each resonator is tuned to respond to a particular frequency that corresponds to a particular message generated by the audio accessory. When the particular message is received, the corresponding resonator resonates to generate an output signal that controls the electronic device.

Abstract: A system for controlling an electronic device, including an accessory coupled to the device having a control interface for receiving at least one input and a tone generator, the accessory configured to, in response to an input, generate a corresponding control tone using the tone generator, and send the control tone and a calibration sequence to the device. The device is operable to receive the calibration sequence and control tone. The device includes a zero-crossing detector operable to determine at least one of the start or ending of each of the calibration sequence and the control tone and having a circuit operable to determine the periods of the calibration sequence and the control tone based on the zero-crossing detector output.

Abstract: According to one aspect, an electronic device adapted to be controlled by an audio accessory. The electronic device includes at least one resonator. Each resonator is tuned to respond to a particular frequency that corresponds to a particular message generated by the audio accessory. When the particular message is received, the corresponding resonator resonates to generate an output signal that controls the electronic device.

Abstract: Various embodiments are described herein for an asymmetrical bus keeper circuit that provides asymmetrical drive towards one logic level. The asymmetrical bus keeper circuit comprises a first inverter stage having an input node and an output node, an asymmetrical inverter stage having an input node and an output node and a feedback stage with an input node and an output node. The input node of the asymmetrical inverter stage is connected to the output node of the first inverter stage. The input node of the feedback stage connected to the output node of the asymmetrical inverter stage and the output node of the feedback stage connected to the input node of the first inverter stage. The asymmetrical stage provides asymmetrical drive towards one logic level.

Abstract: Various embodiments are described herein for an asymmetrical bus keeper circuit that provides asymmetrical drive towards one logic level. The asymmetrical bus keeper circuit comprises a first inverter stage having an input node and an output node, an asymmetrical inverter stage having an input node and an output node and a feedback stage with an input node and an output node. The input node of the asymmetrical inverter stage is connected to the output node of the first inverter stage. The input node of the feedback stage connected to the output node of the asymmetrical inverter stage and the output node of the feedback stage connected to the input node of the first inverter stage. The asymmetrical stage provides asymmetrical drive towards one logic level.

Abstract: Various embodiments are described herein for an asymmetrical bus keeper circuit that provides asymmetrical drive towards one logic level. The asymmetrical bus keeper circuit comprises a first inverter stage having an input node and an output node, an asymmetrical inverter stage having an input node and an output node and a feedback stage with an input node and an output node. The input node of the asymmetrical inverter stage is connected to the output node of the first inverter stage. The input node of the feedback stage connected to the output node of the asymmetrical inverter stage and the output node of the feedback stage connected to the input node of the first inverter stage. The asymmetrical stage provides asymmetrical drive towards one logic level.

Abstract: A portable electronic device provides audio output, such as from a media player application controllable by an ultrasonic remote control signal. Audio processing circuitry, which is normally configured to process audio signals in the human audible range, is configured by a controller to operate in an ultrasonic signal processing mode to detect an ultrasonic control signal, such as generated by a specialized headset. Such a configuration permits the portable electronic device to process ultrasonic control signals using native audio processing circuitry, without the need to add expensive hardware. The ultrasonic signal processing mode is initiated in response to a detected ultrasonic signal processing condition, such as detection of an active media player application or other application software or system software having an audio output function.

Abstract: A system for controlling an electronic device, including an accessory coupled to the device having a control interface for receiving at least one input and a tone generator, the accessory configured to, in response to an input, generate a corresponding control tone using the tone generator, and send the control tone and a calibration sequence to the device. The device is operable to receive the calibration sequence and control tone. The device includes a zero-crossing detector operable to determine at least one of the start or ending of each of the calibration sequence and the control tone and having a circuit operable to determine the periods of the calibration sequence and the control tone based on the zero-crossing detector output.