Cirrus Logic Inc.

Crystal Semiconductor Corporation

Jeff Klaas

Phillip Matthews

Ronald D Malcolm

Mark Gentry

A single chip audio systemincludes a bus interfacedigital to analog convertersan analog mixerand analog spatial enhancement circuitryDigital to analog convertersconvert digital audio data received through bus interfaceinto analog signals. Analog mixermixes signals received from digital to analog converterswith an analog signal received from an external source. Analog spatial enhancement circuitryenhances first and second mixed analog signals output from analog mixer

Single-chip audio circuits, methods, and systems using the same

A system fabricated on a single integrated circuit chip includes a microprocessor operating from a high speed bus and a peripheral bus operating in conjunction with high speed bus through a bus bridge . A first set of processing resources operate from high speed bus and includes an external memory interface , a direct memory access engine for controlling the exchange of information through memory interface , and a boot memory for storing boot code. A second set of processing resources operate from peripheral bus and includes an interrupt controller for issuing interrupt requests to microprocessor , a set of programmable timers for generating timed interrupt signals, and a phase locked loop for generating timing signals.

System-on-a-chip

An audio system includes circuitry for generating an audio data stream and circuitry for generating digital words defining a volume control level. System also includes volume control circuitry for controlling the amplitude of the audio data stream in response to the digital words. Volume control circuitry includes a master register for holding digital words received from circuitry for generating and a slave register for holding a digital word selectively transferred from master register in response to an enable signal. Output control circuitry and receive the audio data stream and apply a preselected gain defined by the digital word held in slave register . Volume control circuitry also includes circuitry for generating the enable signal when a digital word held in the master register changes and the audio data stream output from ouput control circuitry reaches a zero crossing.

Single-chip audio system volume control circuitry and methods

Amplitude control circuitry includes a first register for storing received amplitude control data and a second register for storing amplitude control data transfered from first register . Output circuitry controls the amplitude of a received signal in response to amplitude data transferred from second register. A sensor determines when data stored in first register and second register does not match and enables a comparator when data in first register and, second register does not match. Comparator compares a signal output from output circuitry with a reference signal and generates a signal for enabling the transfer of data from first register to second register when the signal output from output circuitry falls within a window defined by the reference voltage.

Signal amplitude control circuitry and methods

A single chip audio system includes a bus interface , digital to analog converters , an analog mixer , and analog spatial enhancement circuitry . Digital to analog converters convert digital audio data received through bus interface into analog signals. Analog mixer mixes signals received from digital to analog converters with an analog signal received from an external source. Analog spatial enhancement circuitry enhances first and second mixed analog signals output from analog mixer

Single-chip audio circuitry, method, and systems using the same

An audio system,disposed on a single chip includes an output mixer,having inputs for receiving first digital audio data of a first bit width from a first digital-to-analog converter,digital audio data of a second bit width from a second digital-to-analog converter,and analog data from an external port. An output port drives an analog signal output from the output mixer. An input mixer,has inputs for receiving analog data from a plurality of sources and analog-to-digital converters,to convert an analog output from the input mixer into digital data. An input path transmits the digital data output from the analog to digital convertors,to an external digital bus.

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Austin, TX, United States of America

Jeff Klaas