Abstract: Systems, methods, and apparatus for communicating virtual GPIO information generated at multiple source devices and directed to multiple destination devices. A method performed at a device coupled to a serial bus includes generating first virtual GPIO state information representative of state of one or more physical GPIO output pins, asserting a request to transmit the first virtual GPIO state information by driving a data line of the serial bus from a first state to a second state after a start code has been transmitted on a serial bus and before a first clock pulse is transmitted on a clock line of the serial bus, transmitting the first virtual GPIO state information as a first set of bits in a data frame associated with the start code, and receiving second virtual GPIO state information in a second set of bits in the data frame.

Abstract: Systems and methods for handling silence in audio streams are disclosed. In one aspect, a transmitter detects a halt in an audio stream. After detection of the halt in the audio stream, the transmitter embeds a silence signal into the audio stream and transmits the silence signal to associated receivers. The associated receivers may respond to the embedded silence signal by “playing” silence or by using the silence signal to activate a silence protocol. In either event, the associated receivers do not receive the original audio halt and do not produce an unwanted audio artifact.

Abstract: Exemplary aspects of the present disclosure assist in phase alignment for systems having multiple audio sources. For example, in a system having plural microphones, phase alignment may also be assisted by sampling the microphones at the appropriate time relative to when the samples are placed on the audio bus. Further, phase shifts between audio samples are reduced or eliminated by keeping a sample delay constant for samples from the same microphone. Such manipulation of the audio samples reduces phase shifts which reduces the likelihood of an audio artifact capable of being detected by the human ear and thus improves consumer experience.

Abstract: Power reduction through clock management techniques are disclosed. In one aspect, the clock management is applied to a clock signal on a SOUNDWIRE™ communication bus. In particular, a control system associated with a master device on the communication bus may evaluate frequency requirements of audio streams on the communication bus and select a lowest possible clock frequency that meets the frequency requirements. Lower clock frequencies result in fewer clock transitions and result in a net power saving relative to higher clock frequencies. In the event of a clock frequency change, the master device communicates the clock frequency that will be used prospectively to slave devices on the communication bus, and all devices transition to the new frequency at the same frame boundary. In addition to the power savings, exemplary aspects of the present disclosure do not impact an active audio stream.

Abstract: Systems and methods for handling silence in audio streams are disclosed. In one aspect, a transmitter detects a halt in an audio stream. After detection of the halt in the audio stream, the transmitter embeds a silence signal into the audio stream and transmits the silence signal to associated receivers. The associated receivers may respond to the embedded silence signal by “playing” silence or by using the silence signal to activate a silence protocol. In either event, the associated receivers do not receive the original audio halt and do not produce an unwanted audio artifact.

Abstract: Systems and methods for providing split read transactions over an audio communication bus are disclosed. In one aspect, a device that receives a read command informs a requester that data is not yet available and to try again at a future time, potentially outside the traditional response window. In the meantime, the receiving device begins fetching the requested data to have available when the requester makes a subsequent request. By providing a not yet response, data may be fetched from a memory element in a low-power state after it has been taken out of the low-power state or data may be fetched from a remote location or over a slow internal bus.

Abstract: Systems and methods for providing virtual general purpose input/output (GPIO) (VGI) over a time division multiplex (TDM) bus are disclosed. While a SOUNDWIRE bus is particularly contemplated, other TDM buses may also be used to provide the benefits outlined herein. In particular, raw GPIO signals are placed into time slots on a TDM bus without requiring additional overhead or packaging. This arrangement allows all drops on a multi-drop bus to receive the GPIO signals substantially concurrently with latency measured in less than a frame period.

Abstract: A number of ones in the difference between a current pulse code modulated (PCM) audio sample and an immediately preceding audio sample is compared to a number of ones in the current audio sample to determine which has the fewer number of ones. The audio source sends either the difference or the current audio sample, whichever has fewer ones. By reducing the number of ones sent over a non-return to zero inverted (NRZI) audio bus from an audio source to an audio sink, the number of transitions is reduced, which reduces the power consumed relative to a transmission that does not use this process.

Abstract: Low latency transmission systems and methods for long distances in SOUNDWIRE systems are disclosed. In an exemplary aspect, a SOUNDWIRE sub-system is coupled to a long cable through a bridge. The bridge converts SOUNDWIRE signals to signals for transmission over the long cable and converts the signals from the long cable to the SOUNDWIRE signals for transmission in the SOUNDWIRE sub-system. Conversion between signal types may include concatenating signals of a similar type into a group that is serially transmitted over the long cable. Concatenation of bit slots in this manner consumes minimal overhead in bus turnaround, thereby reducing latency. In further aspects, the functionality of the bridge may be incorporated into a headset or a mobile terminal.

Abstract: Systems and methods to transfer master duties to a slave on a communication bus are disclosed. A master of a communication bus determines that one or more slaves are capable of serving as a sub-master, including providing a clock signal and owning control information bits. Once that determination is made, the master may determine that processing within the master is not required for a particular activity on the bus. The master then alerts one such capable slave to prepare to assume sub-master duties. Once the slave confirms that the slave is ready to assume the sub-master duties, the master may transmit a handover frame on the bus, and the slave begins acting as a sub-master. The master may then enter a low-power state, which may promote power savings, reduce heat generation, and provide other advantages.

Abstract: Systems and methods for in-band reset and wake up on a differential audio bus are disclosed. In particular, after entering a low-power mode, a master device opens a drain on a transistor driving the differential audio bus. When a slave device needs the bus to wake, the slave device may transition the state of the bus. On detecting the transition of the bus, the master device may reassert control of the state of the bus and hold the bus in this new state until ready to issue a synchronization sequence. Likewise, an additional aspect of the present disclosure provides a distinctive sequence of holding the bus at a predefined state for an extended duration interrupted by a relatively brief reversal of the state that triggers a reset of all slave devices on the audio bus.

Abstract: Aspects disclosed in the detailed description include scheduled universal serial bus (USB) low-power operations. In this regard, in one aspect, a USB host controller determines a low-power operation schedule for a USB client device. The low-power operation schedule comprises one or more scheduled low-power operation periods, each corresponding to a respective entry time and a respective exit time. The USB host controller communicates the low-power operation schedule to the USB client device using one or more USB standard packets. By scheduling the one or more scheduled low-power operation periods with respective entry and exit times, the USB host controller or the USB client controller is able to start and end the one or more scheduled low-power operation periods without incurring additional signaling, thus improving efficiency of the USB low-power operation. Further, by communicating the low-power operation schedule using USB standard packets, it is possible to preserve compatibility with USB standards.

Abstract: Systems, methods, and apparatus for communication over a serial bus in accordance with an I3C protocol are described. A master device coupled to the serial bus may detect signaling on the serial bus corresponding to an in-band interrupt asserted by a slave device that is addressable by a first device identifier, receive a second device identifier transmitted by the slave device in relation to the in-band interrupt, use the second device identifier to select an execution environment, and interrupt the execution environment responsive to the in-band interrupt. The slave device may use the first device identifier in transactions conducted over the serial bus. After detecting an event generated by an event source, the slave device may initiate an in-band interrupt on the serial bus, and may transmit the second device identifier to indicate the event source during an in-band interrupt handling procedure.

Abstract: Data bus activation in an electronic device is provided. In one aspect, a host circuit determines a cumulative potential representing a cumulative fractional bus activation vote on a data line(s) in the data bus. The host circuit activates the data bus when the cumulative potential is greater than a configurable bus activation threshold. In another aspect, a device circuit(s) determines a selected signal strength threshold that is less than determined signal strength of an incoming signal. Accordingly, the device circuit(s) asserts a fractional potential corresponding to the selected signal strength threshold on the data line(s) as a fractional bus activation vote in the cumulative fractional bus activation vote. By activating the data bus based on the cumulative fractional bus activation vote, the host circuit can support timely data bus activation while preventing the data bus from being falsely activated, thus improving robustness of data bus activation in the electronic device.

Abstract: Full-duplex memory access systems and methods for improved quality of service (QoS) are disclosed. In one aspect, a primary bus owner will evaluate an output from a secondary bus owner when the primary bus owner takes control of the bus to determine if the secondary bus owner has data to send to the primary bus owner and/or is in the midst of a bulk data transfer. If the evaluation determines that there is still data to be transferred, the primary bus owner may refrain from draining an internal register unless a full word is present in the register. By reducing memory access for a partial word in the register, QoS may be improved.

Abstract: Providing zero-overhead frame synchronization using synchronization strobe polarity for SOUNDWIRE Extension buses is disclosed. In one aspect, a downstream-facing interface (DFI) device determines a polarity of a next synchronization strobe of a bitstream based on a value of a next frame synchronization pattern, and adjusts the next synchronization strobe of the bitstream to comprise a signal transition corresponding to the polarity. The processor-based DFI device then transmits the bitstream containing the next synchronization strobe (e.g., via a SOUNDWIRE Extension bus, such as a SOUNDWIRE-XL or SOUNDWIRE-NEXT bus, to one or more upstream-facing interface (UFI) devices). In another aspect, a processor-based UFI device receives the bitstream, and detects the encoded polarity of the synchronization strobe.

Abstract: Systems, methods, and apparatus for communication over a serial bus in accordance with an I3C protocol are described that enable a non-participating device to cause a master device on an I3C bus transmit a STOP condition that terminates a transaction with a slave device coupled to the I3C bus. A method performed at a master device coupled to a serial bus includes initiating a transaction between the master device and a first slave device, terminating the transaction before completion of the transaction when a second slave device intervenes in the transaction, and servicing the second slave device after terminating the transaction. The transaction may include transmissions of data frames over the serial bus. The second slave device may intervene when it is not a party to the transaction.

Abstract: System, methods and apparatus are described that can improve available bandwidth on a SoundWire bus without increasing the number of pins used by the SoundWire bus. A method performed at a master device coupled to a SoundWire bus includes providing a clock signal by a first master device over a clock line of a SoundWire bus to a first slave device and a second slave device coupled to the SoundWire bus, transmitting first control information from the first master device to the first slave device over a first data line of the SoundWire bus, and transmitting second control information from the first master device to the second slave device over a second data line of the SoundWire bus. The first control information may be different from the second control information and is transmitted concurrently with the second control information.

Abstract: Device identification generation in electronic devices to allow external control, such as selection or reprogramming, of device identification for bus communications identification, is disclosed. In this manner, device identifications of electronic devices coupled to a common communications bus in a system can be selected or reprogrammed to ensure they are unique to avoid bus communications collisions. In certain aspects, to select or reprogram a device identification in an electronic device, an external source can be electrically coupled to the electronic device. The external source closes a circuit with a device identification generation circuit in the electronic device. The closed circuit provides a desired electrical characteristic detectable by the device identification generation circuit. The device identification generation circuit is configured to generate a device identification as a function of the detected electrical characteristics of the closed circuit from the external source.

Abstract: A serial low-power inter-chip media bus (SLIMbus) communications link is deployed in apparatus having multiple integrated circuit (IC) devices. Systems, methods and apparatus are described that can improve the operation of SLIMbus communications links. A method includes determining that an interrupt asserted within a first device coupled to a SLIMbus is directed to a second device coupled to the SLIMbus and generating an in-band interrupt (IBI) message identifying the first device as an interrupt source, the second device as an interrupt target, and including information identifying a type and a status associated with the interrupt, and transmitting the IBI message to the second device over the SLIMbus.