Abstract: Systems, methods, and apparatus for improving end-to-end timing closure of a serial bus are described. An apparatus is coupled to a serial bus through an interface circuit and has a clock generator that provides a first clock signal, a delay circuit that is adapted to generate a second clock signal by delaying the first clock signal, and a controller that is configured to cause the interface circuit to use an edge of the first clock signal to initiate transmission of a first data bit over the serial bus during a write operation, delay the first clock signal to obtain a second clock signal, and cause the interface circuit to use an edge of the second clock signal to capture a second data bit from the serial bus during a read operation. The edge of the second clock signal is delayed with respect to the edge of the first clock signal.

Abstract: Systems, methods, and apparatus for communication virtualized general-purpose input/output (GPIO) signals over a serial communication link. An apparatus includes a serial bus, and an originating device and destination device coupled to the serial bus. The originating device may be configured to generate a first virtual GPIO packet that carries a payload representative of signaling state of physical GPIO in the originating device, generate a second virtual GPIO packet that carries a payload representative of an event generated by a processor in the originating device, and transmit the first and second virtual GPIO packets on the serial bus. The destination device may be configured to receive the second virtual GPIO packet from the serial bus, and communicate the event to a processor of the destination device or modify signaling state of physical GPIO in the destination device in accordance with the payload of the second virtual GPIO packet.

Abstract: Systems, methods, and apparatus for communication over a serial bus in accordance with an I3C protocol are described that enable a slave device to request that a bus master device terminate a write transaction with the slave device. The serial bus may be operated according to an I3C single data rate protocol. In various aspects of the disclosure, a method performed at a master device coupled to a serial bus includes initiating a write transaction between the master device and a slave device, where the write transaction includes a plurality of data frames, and at least one data frame is configured with a transition bit in place of a parity bit. The method may include terminating the write transaction when the slave device drives a data line of the serial bus while receiving the transition bit.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in one or more modes that employ additional wires for communicating data. A method includes providing a data payload for a data frame to be transmitted over a plurality of data lanes of a multilane serial bus, providing a preamble to precede the data payload in transmission over the multilane serial bus, configuring one or more repurposed bit fields in the data frame to indicate that a multi-bit cyclic redundancy check is provided in the data frame, and transmitting the data frame over the multilane serial bus in accordance with a clock signal transmitted on a clock lane of the multilane serial bus. At least one bit of the multi-bit cyclic redundancy check is transmitted on two or more data lanes of the plurality of data lanes.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in one or more modes that employ additional wires for communicating data. A method includes providing a data payload for a first data frame to be transmitted over a plurality of data lanes of a multilane serial bus operated in accordance with an I3C protocol, providing one or more indicators of validity of one or more bytes included in the data payload, and transmitting the first data frame over the multilane serial bus in accordance with a clock signal transmitted on a clock lane of the multilane serial bus.

Abstract: Systems, methods and apparatus are described that offer improved performance of a sensor bus. A first command is transmitted to devices coupled to a serial bus operated in a first mode in accordance with a first protocol to cause the serial bus to be operated in a second mode. After communicating in accordance with a second protocol while the serial bus is operated in the second mode, a second command is transmitted to the plurality of devices in accordance with the first protocol to terminate the second mode. In the second mode, extra symbols inserted into a sequence of symbols transmitted on the serial bus prevent the occurrence of an unintended signaling state on the serial bus. Pulses transmitted on a wire of the serial bus in the second mode may have their duration limited such that a filter of a second device suppresses the limited-duration pulses.

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, methods and apparatus are described that offer improved performance of a sensor bus. A first command is transmitted to devices coupled to a serial bus operated in a first mode in accordance with a first protocol to cause the serial bus to be operated in a second mode. After communicating in accordance with a second protocol while the serial bus is operated in the second mode, a second command is transmitted to the plurality of devices in accordance with the first protocol to terminate the second mode. In the second mode, extra symbols inserted into a sequence of symbols transmitted on the serial bus prevent the occurrence of an unintended signaling state on the serial bus. Pulses transmitted on a wire of the serial bus in the second mode may have their duration limited such that a filter of a second device suppresses the limited-duration pulses.

Abstract: Systems, methods and apparatus are described that offer improved performance of a sensor bus. A method includes transmitting a first command on a serial bus while operating in a first mode of operation, exchanging first data with the first device in accordance with a second protocol associated with the second mode of operation, and exchanging second data with the first device in accordance with the second protocol after the first period of time. The first command may be transmitted in accordance with a first protocol to cause a first device to operate in a second mode of operation. The first device may be idle for a first period of time after the first data has been exchanged.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in multiple modes that employ additional wires for communicating data such that the bus width may be dynamically extended to improve bandwidth and/or throughput. One method includes transmitting a set of frames or sequences of symbols configured to carry up to a maximum number of data bytes over the serial bus, transmitting control signaling over a first data lane and the clock lane after the set of frames or sequences of symbols has been transmitted, and transmitting a first signal over a second data lane while transmitting the control signaling that may indicate whether the set of frames or sequences of symbols includes padding. The first signal may indicate a number of valid bytes or words in the set of frames or sequences of symbols.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in one or more modes that employ additional wires for communicating data. A method includes configuring a first interface to exchange data over two primary wires of a serial bus in accordance with a first I3C protocol, and configuring a second interface to communicate over at least one secondary wire in accordance with a second I3C protocol. In one example, the first data is encoded in a sequence of symbols representing signaling state of the two primary wires. A recovered clock signal may be derived from transitions between symbol transmission intervals in the first interface may be used to control double data rate communication through the second interface.

Abstract: Systems, methods, and apparatus are described that enable a device to indicate availability of priority data to be communicated over a half-duplex serial bus without waiting for an ongoing transmission to be completed. In-datagram critical signaling is accommodated without breaking backward compatibility. A method implemented at a transmitting device coupled to a serial bus includes transmitting a data byte over a first line of the serial bus to a receiving device in accordance with a clock signal transmitted by a master device on a second line of the serial device, detecting a first pulse on the first line of the serial bus during a cycle of the clock signal designated for an acknowledgement or negative acknowledgement by the second device, and processing an alert indicated by the first pulse.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in multiple modes that employ additional wires for communicating data such that the bus width may be dynamically extended to improve bandwidth and/or throughput. One method includes transmitting a set of frames or sequences of symbols configured to carry up to a maximum number of data bytes over the serial bus, transmitting control signaling over a first data lane and the clock lane after the set of frames or sequences of symbols has been transmitted, and transmitting a first signal over a second data lane while transmitting the control signaling that may indicate whether the set of frames or sequences of symbols includes padding. The first signal may indicate a number of valid bytes or words in the set of frames or sequences of symbols.

Abstract: Systems, methods, and apparatus for serial bus arbitration are described. A method for arbitrating access to a serial bus includes providing a clock signal on a first line of the serial bus, configuring a line driver coupled to a second line of the serial bus for open-drain operation, transmitting an address header through the line driver in accordance with timing provided by the clock signal, detecting that the second line is driven low in a bit interval corresponding to the at least one most-significant bit, configuring the line driver for push-pull operation after detecting that the second line has been driven low, and increasing rate at which clock pulses are provided in the clock signal after detecting that the second line has been driven low. The address header may include at least one most-significant bit that has a zero-value when a high-priority device is addressed.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in one or more modes that employ additional wires for communicating data. A method for transmitting data over a serial bus having multiple data lanes includes providing a plurality of frames, each frame being configured to carry up to a maximum number of data bytes, transmitting a first frame over the serial bus, where the first frame is filled with first data bytes, notifying one or more devices of unavailability of an alert opportunity prior to transmitting the first frame, transmitting a second frame over the serial bus, where the first frame includes second data bytes less in number than the maximum number of data bytes, and notifying the one or more devices that the second frame provides an opportunity to launch an alert after transmission of the second data bytes.

Abstract: A device is provided that has a bus including a first line and a second line. A first set of devices are coupled to the bus and, in a first mode of operation, configured to use the first line for data transmissions and use the second line for a first clock signal. One or more additional lines are connected between two or more of the devices in the first set of devices for transmitting signaling between the two or more devices. A second set of devices are configured to use the bus and at least one of the additional lines for data transmissions in a second mode of operation, where in the second mode of operation symbols are encoded across the first line, the second line, and the at least one of the additional lines.

Abstract: Systems, methods, and apparatus for communication virtualized general-purpose input/output (GPIO) signals over a serial communication link. An apparatus includes a serial bus, and an originating device and destination device coupled to the serial bus. The originating device may be configured to generate a first virtual GPIO packet that carries a payload representative of signaling state of physical GPIO in the originating device, generate a second virtual GPIO packet that carries a payload representative of an event generated by a processor in the originating device, and transmit the first and second virtual GPIO packets on the serial bus. The destination device may be configured to receive the second virtual GPIO packet from the serial bus, and communicate the event to a processor of the destination device or modify signaling state of physical GPIO in the destination device in accordance with the payload of the second virtual GPIO packet.

Abstract: Systems, methods, and apparatus are described that enable a serial bus to be operated in one or more modes that employ additional wires for communicating data. An apparatus has a bus including a first lane and a second lane, a plurality of devices coupled to the bus and, in a first mode of operation, the plurality of devices is configured to exchange data in a signal transmitted on the first lane in accordance with timing provided by a clock signal transmitted on the second lane. The apparatus may include one or more additional lanes connecting two or more devices in the plurality of devices, the two or more devices being configured to use the first lane and at least one of the additional lanes for data transmissions in a second mode of operation.

Abstract: A device is provided that has a bus including a first line and a second line. A first set of devices are coupled to the bus and, in a first mode of operation, configured to use the first line for data transmissions and use the second line for a first clock signal. One or more additional lines are connected between two or more of the devices in the first set of devices for transmitting signaling between the two or more devices. A second set of devices are configured to use the bus and at least one of the additional lines for data transmissions in a second mode of operation, where in the second mode of operation symbols are encoded across the first line, the second line, and the at least one of the additional lines.

Abstract: Disclosed are methods and apparatus for calculating sensor timing corrections at a sensor device. The methods and apparatus determine a sampling period as a number of cycles of an internal clock counted while a configured number of samples is captured in a slave device, determine a time interval between samples using an offset from a time of an observed occurrence of a hardware event on a communication link, the offset being received in a command from a master device, and adjust the time interval between samples by iterative digital approximation to correct for differences between timing of the slave device and the master device while concurrently calculating a watermark time corresponding to a sample start time configured by the master device for one or more slave devices.