Abstract: Methods and apparatuses for operating a direct communication over a serial communication bus are provided. An apparatus includes a master having a host controller. The host controller is configured to communicate with a first slave and with a second slave via a serial communication bus using at least one master-slave address, in accordance with a serial communication protocol. The host controller includes a master-slave module configured to operate communication with the first slave and with the second slave via the serial communication bus in accordance with the serial communication protocol and be in a low-power mode while the first slave and the second slave are in a direct communication. The host controller includes an always-on module configured to, while the master-slave module is in the low-power mode, clock the serial communication bus for the direct communication.

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: Systems, methods, and apparatus associated with a device coupled to a serial bus are described. A method data communication includes providing a clock signal on a first line of the serial bus, determining a winning device based on an address received from a second line of the serial bus during a bus arbitration procedure, determining a first sampling point for sampling a first data signal that is received from the second line of the serial bus based on timing of the clock signal and a first delay value corresponding to the winning device, and capturing a first bit of data from the second line of the serial bus at the sampling point. The serial bus may be operated in accordance with an I3C protocol.

Abstract: Systems, methods, and apparatus for serial bus arbitration are described. A method for managing transactions executed on a serial bus includes configuring a slave device with information identifying a first timeslot in a first transaction type that is conducted repetitively in accordance with a repetitive time period (RTP) schedule, initiating a first transaction of the first transaction type at a first point in time that is defined by the RTP schedule, and exchanging first data with the slave device during the first timeslot in the first transaction. The serial bus may be operated in accordance with an asynchronous protocol. In one example, the asynchronous protocol is an I3C protocol.

Abstract: Systems, methods, and apparatus are described that enable communication of in-band reset signals over an I3C serial bus. A method performed at a slave device includes driving a data line of the I3C serial bus from a high state to a low state before a first clock pulse is received from a clock line of the I3C serial bus after a start condition has been provided on the I3C serial bus, where driving the data line from the high state to the low state produces an initial pulse on the data line, transmitting one or more additional pulses on the data line before the first clock pulse is transmitted on the clock line, and driving the data line low until a rising edge of the first clock pulse is detected on the clock line after each of the plurality of additional pulses has been successfully transmitted on the data line.

Abstract: Systems and methods for reducing latency on long distance point-to-point links where the point-to-point link is a Peripheral Component Interconnect (PCI) express (PCIE) link that modifies a receiver to advertise infinite or unlimited credits. A transmitter sends packets to the receiver. If the receiver's buffers fill, the receiver, contrary to PCIE doctrine, drops the packet and returns a negative acknowledgement (NAK) packet to the transmitter. The transmitter, on receipt of the NAK packet, resends packets beginning with the one for which the NAK packet was sent. By the time these resent packets arrive, the receiver will have had time to manage the packets in the buffers and be ready to receive the resent packets.

Abstract: Systems and methods for scrambling data-port audio in SOUNDWIRE™ systems include a scramble enable feature that allows a data source to scramble an outgoing channel content with a cyclic linear feedback shift register (LFSR) using a pseudo-random binary sequence (PRBS) such as, but not limited to, the PRBS defined in the SOUNDWIRE specification. Data ports for audio sinks receiving the scrambled content descramble the content for use by the audio sink. In a specific exemplary aspect, an output of the LFSR is added or subtracted with the audio data to make the microphones independent of one another and reduce crosstalk.

Abstract: Systems and methods for payload transport for simple pulse division multiplexed (PDM) devices provide for simple PDM devices to have a phase-locked loop (PLL) that operates at a frequency corresponding to an audio rate on an associated audio bus. Additional parameters are defined relative to a starting synchronization event. The parameters inform a simple PDM device from which bit slots to extract data or into which bit slots to write data. In a further exemplary aspect, a low-cost delay-locked loop (DLL) is used to assist the simple PDM device in calculating the designated bit slots.

Abstract: Systems and methods for multi-threshold sensing at an audio receiver, and systems and methods for calibrating an audio system to optimize for the specific configuration of the audio system are disclosed herein. In some implementations of a multi-threshold receiver, at least one additional voltage level is selected to trigger latching events within the receiver based on changes of the receiver input (which includes differential signals Vp and Vn) and in turn, to generate internal signals within the multi-threshold receiver, and then logic operations are performed on these internal signals to generate the output of the multi-threshold receiver.

Abstract: Security techniques for a Peripheral Component Interconnect (PCI) express (PCIE) system include a transport layer protocol (TLP) packet that has a prepended TLP prefix indicating the security features of the TLP packet and an integrity check value (ICV) appended to the TLP packet. The ICV is based on the TLP packet and any TLP prefixes including a security prefix. At a receiver, if the ICV does not match, then the receiver has evidence that the TLP packet may have been subjected to tampering. Further, the TLP packet may be encrypted to prevent snooping, and this feature would be indicated in the TLP prefix. Still further, the TLP prefix may include a counter that may be used to prevent replay attacks. PCIE contemplates flexible TLP prefixes, and thus, the standard readily accommodates the addition of a TLP prefix which indicates the security features of the TLP packet.

Abstract: Systems, methods, and apparatus are described that enable communication of in-band reset signals over an I3C serial bus. A method performed at a slave device includes driving a data line of the I3C serial bus from a high state to a low state before a first clock pulse is received from a clock line of the I3C serial bus after a start condition has been provided on the I3C serial bus, where driving the data line from the high state to the low state produces an initial pulse on the data line, transmitting one or more additional pulses on the data line before the first clock pulse is transmitted on the clock line, and driving the data line low until a rising edge of the first clock pulse is detected on the clock line after each of the plurality of additional pulses has been successfully transmitted on the data line.

Abstract: Methods and apparatuses for operating a direct communication over a serial communication bus are provided. An apparatus includes a master having a host controller. The host controller is configured to communicate with a first slave and with a second slave via a serial communication bus using at least one master-slave address, in accordance with a serial communication protocol. The host controller includes a master-slave module configured to operate communication with the first slave and with the second slave via the serial communication bus in accordance with the serial communication protocol and be in a low-power mode while the first slave and the second slave are in a direct communication. The host controller includes an always-on module configured to, while the master-slave module is in the low-power mode, clock the serial communication bus for the direct communication.

Abstract: Systems, methods, and apparatus are described. An apparatus provides a clock signal, transmits an address on a second line of the serial bus followed by a read/write bit configured to initiate a read transaction, and delays a pulse in the clock signal after transmitting the read/write bit. The pulse may be delayed for a first duration configured to accommodate a latency associated with a first slave device that is a participant in the read transaction. The apparatus may receive an acknowledgement from the first slave device while the pulse is being transmitted and may receive a first data byte from the first slave device after receiving the acknowledgment. The apparatus may stall the clock signal for a second duration after receiving the first data byte from the first slave device, and receive a second data byte from the first slave device after the acknowledgment.

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: Delayed bank switch commands in an audio system such as a SOUNDWIRE audio system may have slaves that have had a delay register added to register banks for each data port. When a bank switch command is received, a slave consults the delay register and delays switching by a number of frames indicated in the delay register. Such delays may be used to prevent interpreting non-audio data as part of a data stream, particularly at start up and closure of audio streams. If an audio stream is active, the delay may be set to zero. By precluding the evaluation of non-audio data, audio artifacts may be avoided and a better user experience provided.

Abstract: Systems and methods for power conservation in a SOUNDWIRE audio bus provide a pulse density modulated (PDM) audio stream at an audio source to an encoder. The encoder has a plurality of encoding states corresponding to bit patterns. The encoder compares bits of the audio stream to available bit patterns and selects an encoding state. The audio source sends the encoding state to an audio sink and then sends data to the audio sink based on encoding using the selected encoding state. The data is sent over a non-return to zero inverted (NRZI) audio bus. As the audio stream changes bit patterns, the encoder may select different more efficient encoding states and provide updates to the audio sink of changes in the encoding state.

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: Systems, methods, and apparatus are described for communicating virtual GPIO (VGI) information between multiple source devices and multiple consuming devices. A method for facilitating communication of VGI state over a serial bus includes determining that an in-band interrupt has been asserted on the serial bus while the serial bus is idle, participating in an exchange of VGI state when a first bit of a device address transmitted during bus arbitration associated with the in-band interrupt has a first value, receiving a plurality of bits of VGI state during the exchange of VGI state, including bits transmitted by multiple devices coupled to the serial bus, and mapping at least one bit in the plurality of bits of VGI state to a physical GPIO pin. Transmission of at least a second bit of the device address is suppressed when the first bit of a device address has the first value.

Abstract: Lightweight Universal Serial Bus (USB) compound device implementation is disclosed. In particular, a compound device is provided that includes a parsing circuit that parses addresses and endpoint values for comparison to a look-up table and translation thereof for provision of updated addresses and endpoint values to a USB device controller. The USB device controller then uses the updated endpoint values to route information to a correct destination. In this manner, the benefits of a USB compound device are provided without the area and power penalty that normally accompanies a USB compound device.

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.