Communication system, communication method, and program

Abstract

The present disclosure pertains to a communication system, a communication method, and a program that make it possible to more reliably achieve synchronization. After transferring controller authority to a sensor hub device, a host device transmits, to the sensor hub device, time stamp information conforming to a reference time of a grandmaster, and the sensor hub device transmits, to a first sensor device, synchronization information based on the reference time of the grandmaster estimated from the time stamp information. The present technology can be applied to, for example, a communication system that performs communication via an I3C bus and Ethernet.

Description

Communication systems and communication methods, and programs

[0001] This disclosure relates to communication systems and communication methods, as well as programs, and more particularly to communication systems and communication methods, as well as programs that enable more reliable synchronization.

[0002] Traditionally, the MIPI (Mobile Industry Processor Interface) Alliance has developed I3C (Improved Inter-Integrated Circuits) as a communication standard that enables faster and more efficient communication between ICs (Integrated Circuits). In I3C, the communication system consists of a host device with primary controller functionality, which is the main controller device that takes the lead in controlling communication, and target devices that communicate subordinately according to the control of the host device.

[0003] For example, I3C defines two Timing Control functions for controlling the timing of data transmission and reception: Sync Mode for synchronous communication and Async Mode for asynchronous communication. In Sync Mode, the host device sends a common clock signal, the ST (Synctick) signal, to all target devices, and multiple target devices can transmit data at synchronized timings according to the ST signal. In Async Mode, multiple target devices can transmit data at independent timings, and the host device can synchronize the data based on timestamps attached to the data.

[0004] In addition, in I3C, a Multiple Controllers function is defined that enables the transfer of the controller right, which is the right to control communication as a controller device. As a result, it is possible to provide a target device that normally operates as a target device and can control communication as a controller device when the controller right is transferred from the host device. For example, in a communication system configured with a plurality of sensor devices operating as target devices, a sensor device having the function of a secondary controller can be used as a sensor hub device that controls communication with a plurality of other sensor devices.

[0005] For example, Patent Document 1 discloses a communication system in which a master determines whether a secondary master that has made a request has group management capabilities when transferring the leadership of communication in response to a request from the secondary master.

[0006] Japanese Patent Application Laid-Open No. 2018-206267

[0007] By the way, conventionally, when the controller right is transferred from the host device to the sensor hub device, the sensor hub device becomes independent from the grand master that provides the reference time indicating the timing at which the host device transmits the ST signal. As a result, for example, it is assumed that it becomes difficult to synchronize between a sensor device whose communication is controlled by the sensor hub device and a sensor device whose communication is controlled by the host device using a communication standard other than I3C.

[0008] The present disclosure has been made in view of such a situation, and aims to enable more reliable synchronization.

[0009] A communication system in one aspect of this disclosure can communicate using a first communication standard and a second communication standard, and comprises a host device which is a primary controller device that takes the lead in controlling communication in the first communication standard; a sensor hub device which normally operates as a target device in the first communication standard and functions as a secondary controller that controls communication in the first communication standard when the controller rights to control communication in the first communication standard are transferred from the host device; a first sensor device which operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device which communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, wherein the host device transmits timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device, and the sensor hub device transmits synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

[0010] A communication method in one aspect of the present disclosure is a communication method for a communication system comprising: a host device which is a primary controller device that can communicate using a first communication standard and a second communication standard and takes the lead in controlling communication in the first communication standard; a sensor hub device which normally operates as a target device in the first communication standard and functions as a secondary controller that controls communication in the first communication standard when the controller rights for controlling communication in the first communication standard are transferred from the host device; a first sensor device which operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device which communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, the method comprising: the host device transmitting timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device; and the sensor hub device transmitting synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

[0011] A program in one aspect of this disclosure causes a computer in a communication system comprising: a host device that can communicate using a first communication standard and a second communication standard and is a primary controller device that takes the lead in controlling communication in the first communication standard; a sensor hub device that normally operates as a target device in the first communication standard and, when the controller rights to control communication in the first communication standard are transferred from the host device, functions as a secondary controller that controls communication in the first communication standard as the controller device; a first sensor device that operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device that communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, to execute a process including: the host device transmitting timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device; and the sensor hub device transmitting synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

[0012] In one aspect of this disclosure, the communication system is capable of communicating using a first communication standard and a second communication standard, and comprises a host device which is a primary controller device that takes the lead in controlling communication using the first communication standard; a sensor hub device which normally operates as a target device in the first communication standard and functions as a secondary controller that controls communication using the first communication standard when the controller rights for controlling communication using the first communication standard are transferred from the host device; a first sensor device which operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device which communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of the grandmaster owned by the host device. After the host device transfers controller rights to the sensor hub device, timestamp information conforming to the reference time of the grandmaster is transmitted to the sensor hub device, and synchronization information based on the reference time of the grandmaster estimated from the timestamp information is transmitted from the sensor hub device to the first sensor device.

[0013] This is a block diagram showing an example configuration of a first embodiment of a communication system to which this technology is applied. This is an example of a timing chart for communication via the I3C bus using a conventional communication system. This is an example of a timing chart for communication via the I3C bus using the communication system in Figure 1. This is a flowchart explaining the timing control process. This is a block diagram showing an example configuration of a second embodiment of a communication system to which this technology is applied. This is an example of a timing chart for communication via the I3C bus using the communication system in Figure 5. This is a flowchart explaining the timing control process. This is a block diagram showing an example configuration of a computer to which this technology is applied.

[0014] The following describes in detail a specific embodiment of this technology, with reference to the drawings.

[0015] <First Configuration Example of a Communication System> Referring to Figures 1 to 4, a configuration example of a first embodiment of a communication system to which this technology is applied will be described.

[0016] Figure 1 is a block diagram showing an example configuration of a first embodiment of the communication system.

[0017] As shown in Figure 1, the communication system 11 comprises a host device 21, a sensor hub device 22, a sensor device 23a-1, a sensor device 23a-2, and a sensor device 23b. The host device 21, the sensor hub device 22, the sensor device 23a-1, and the sensor device 23a-2 are connected via an I3C bus, while the host device 21 and the sensor device 23b are connected via Ethernet.

[0018] The host device 21 functions as a primary controller, which is the main controller device that takes the lead in controlling communication via the I3C bus. The sensor hub device 22 normally operates as a target device in communication via the I3C bus, and when controller rights are transferred from the host device 21, it functions as a secondary controller, controlling communication via the I3C bus. Sensor devices 23a-1 and 23a-2 function as target devices in communication via the I3C bus.

[0019] For example, in the communication system 11, when communication via the I3C bus is initiated, the host device 21 can perform the initial setup of the I3C bus and then, in response to a request from the sensor hub device 22, transfer controller rights to the sensor hub device 22. When the host device 21 has controller rights, the sensor hub device 22 operates as a target device, and when the sensor hub device 22 has controller rights, the host device 21 operates as a target device.

[0020] In Figure 1, blocks that become inactive when the sensor hub device 22 has controller rights (i.e., the I3C controller 33 and controller control unit 34 of the host device 21, and the I3C target 42 of the sensor hub device 22) are shown with dashed lines.

[0021] The host device 21 is configured to include a multiplexer 31, an I3C target 32, an I3C controller 33, a controller control unit 34, an Ethernet processing unit 35, a grandmaster 36, and a processor 37.

[0022] The multiplexer 31 can switch between inputting and outputting signals between the I3C target 32 ​​and the I3C bus, and inputting and outputting signals between the I3C controller 33 and the I3C bus. For example, as shown in the figure, when the I3C target 32 ​​is active, the multiplexer 31 outputs signals supplied from the I3C target 32 ​​to the I3C bus and supplies signals input via the I3C bus to the I3C target 32.

[0023] When the host device 21 is operating as a target device, the I3C target 32 ​​communicates via the I3C bus according to the control of the sensor hub device 22, which has controller rights. In addition, I3C defines IBI (In-Band Interrupts), a function that allows target devices to perform interrupt communication, and the I3C target 32 ​​can transmit timestamp information supplied from the processor 37 to the sensor hub device 22 using IBI.

[0024] The I3C controller 33 controls communication via the I3C bus based on the control of the controller control unit 34 when the host device 21 has controller rights. The I3C controller 33 is inactive when the host device 21 is operating as a target device.

[0025] The controller control unit 34 controls the I3C controller 33 according to instructions from the processor 37. The controller control unit 34 is inactive when the host device 21 is operating as a target device.

[0026] The Ethernet processing unit 35 performs processing related to communication via Ethernet with the Ethernet processing unit 54 of the sensor device 23b according to instructions from the processor 37. For example, the Ethernet processing unit 35 can transmit reference time information indicating the reference time of the grandmaster 36, which is supplied from the grandmaster 36 via the processor 37, to the sensor device 23b via PTP (Peer-to-Peer) communication over Ethernet.

[0027] The grandmaster 36 supplies the processor 37 with a reference time that indicates the timing for transmitting the synchronization signal ST in Sync Mode.

[0028] The processor 37 can perform various processes necessary for the host device 21 to communicate in the communication system 11 and can issue instructions to each block that makes up the host device 21. For example, when the host device 21 is set to Async Mode by the sensor hub device 22, the processor 37 generates timestamp information (Async timestamp) to control the timing so that sensing data is output synchronously in Async Mode, in accordance with the reference time supplied by the grandmaster 36, and supplies it to the I3C target 32. The processor 37 also supplies reference time information indicating the reference time supplied by the grandmaster 36 to the Ethernet processing unit 35.

[0029] The sensor hub device 22 comprises a multiplexer 41, an I3C target 42, an I3C controller 43, a controller control unit 44, and a processor 45.

[0030] The multiplexer 41 can switch between inputting and outputting signals between the I3C target 42 and the I3C bus, and inputting and outputting signals between the I3C controller 43 and the I3C bus. For example, as shown in the figure, when the I3C controller 43 is active, the multiplexer 41 outputs signals supplied from the I3C controller 43 to the I3C bus and supplies signals input via the I3C bus to the I3C controller 43.

[0031] The I3C target 42 communicates via the I3C bus according to the control of the host device 21, which has controller rights, when the sensor hub device 22 is operating as a target device. The I3C target 42 is inactive when the sensor hub device 22 has controller rights.

[0032] The I3C controller 43 controls communication via the I3C bus based on control by the controller control unit 44 when the sensor hub device 22 has controller rights. For example, when the I3C controller 43 receives timestamp information transmitted from the host device 21 using IBI, it supplies the timestamp information to the processor 45 via the controller control unit 44.

[0033] The I3C controller 43 then transmits synchronization information, which is information for synchronizing the sensor hub device 22 with sensor devices 23a-1 and 23a-2 in Sync Mode, to sensor devices 23a-1 and 23a-2 via the I3C bus, based on the reference time of the grandmaster 36 estimated by the processor 45 from the timestamp information. Here, the synchronization information includes ST, which is a synchronization signal that synchronizes the timing between devices on the I3C bus, and DT, which is the delay time from the reference time of the grandmaster 36 estimated by the processor 45 from the timestamp information to ST. For example, the delay time included in the synchronization information is determined from the delay time until the I3C target 32 ​​transmits the timestamp information, the delay time on the I3C bus that occurs when transmitting the timestamp information, the reference estimation time required for the processor 45 to estimate the reference time of the grandmaster 36 based on the timestamp information, and the delay time on the I3C bus that occurs when transmitting the synchronization information.

[0034] The controller control unit 44 controls the I3C controller 43 according to instructions from the processor 45.

[0035] The processor 45 can perform various processes necessary for the sensor hub device 22 to communicate in the communication system 11 and can issue instructions to each block that makes up the sensor hub device 22. For example, each time time timestamp information is supplied from the I3C controller 43, the processor 45 can estimate the reference time of the grandmaster 36 of the host device 21 based on the timestamp information and notify the I3C controller 43 of the reference time via the controller control unit 44.

[0036] Sensor device 23a-1 comprises an I3C target 51, a sensor control unit 52a, and a measurement unit 53a. Sensor device 23a-2 is configured similarly to sensor device 23a-1, and a detailed explanation of it is omitted. Furthermore, when there is no need to distinguish between sensor device 23a-1 and sensor device 23a-2, they will be referred to as sensor device 23a.

[0037] If the sensor hub device 22 has controller rights, the I3C target 51 communicates via the I3C bus according to the control of the sensor hub device 22's I3C controller 43. For example, when synchronization information is transmitted from the sensor hub device 22's I3C controller 43 via the I3C bus, the I3C target 51 receives the synchronization information and supplies it to the sensor control unit 52a.

[0038] The sensor control unit 52a generates an event trigger a that instructs the output of sensing data at a timing synchronized with the reference time of the grandmaster 36 estimated by the processor 45, based on synchronization information supplied via the I3C target 51, and supplies it to the measurement unit 53a. Then, the sensor control unit 52a supplies the sensing data supplied from the measurement unit 53a to the I3C target 51 in accordance with the event trigger a, and causes it to be transmitted to the sensor hub device 22 via the I3C bus.

[0039] The measurement unit 53a can perform sensing according to the functions of each sensor device 23a, acquires sensing data at a timing according to the event trigger a supplied from the sensor control unit 52a, and supplies it to the sensor control unit 52a.

[0040] The sensor device 23b is configured to include an Ethernet processing unit 54, a sensor control unit 52b, and a measurement unit 53b.

[0041] The Ethernet processing unit 54 performs processing related to communication via Ethernet with the Ethernet processing unit 35 of the host device 21. For example, the Ethernet processing unit 54 receives reference time information transmitted from the host device 21 via PTP communication over Ethernet and supplies it to the sensor control unit 52b.

[0042] The sensor control unit 52b generates an event trigger b that instructs the output of sensing data at a timing according to the reference time of the grand master 36 indicated by the reference time information supplied from the Ethernet processing unit 54, and supplies it to the measurement unit 53b. Then, the sensor control unit 52b supplies the sensing data supplied from the measurement unit 53b according to the event trigger b to the Ethernet processing unit 54, and causes it to be transmitted to the host device 21.

[0043] The measurement unit 53b can perform sensing according to the functions provided in the sensor device 23b, acquires sensing data at a timing according to the event trigger b supplied from the sensor control unit 52b, and supplies it to the sensor control unit 52b.

[0044] The communication system 11 configured as described above can more reliably synchronize between the sensor device 23a that communicates via the I3C bus and the sensor device 23b that communicates via Ethernet, as compared with, for example, a communication system (hereinafter referred to as a conventional communication system) configured to be completely independent from the grand master 36 of the host device 21 when the sensor hub device 22 has the controller right.

[0045] FIG. 2 shows an example of a timing chart of communication via the I3C bus by a conventional communication system.

[0046] First, when communication via the I3C bus starts, the host device 21 has the controller right, and the host device 21 performs the initial setting of the I3C bus. After that, when the sensor hub device 22 transmits a CRR (Controller Role Request) requesting the transfer of the controller right to the host device 21, the host device 21 performs communication (Role change) necessary to transfer the controller right to the sensor hub device 22. As a result, the host device 21 operates as a target device, and the sensor hub device 22 controls communication via the I3C bus as a controller device.

[0047] Then, as an initial setting of timing control in communication via the I3C bus, the sensor hub device 22 having the controller right transmits, via the I3C bus, a TPH (Procedure Repetition Time) indicating a synchronous communication cycle, a TU (Time Unit) indicating a time unit, and an ODR (Output Data Rate) indicating a data rate. Then, the sensor hub device 22 sets the Async Mode for the host device 21.

[0048] After that, the processor 45 of the sensor hub device 22 shifts from the start processing mode to the timing control operation mode, and transmits, via the I3C bus, synchronous information (ST + DT) including the unique reference time of the sensor hub device 22 (timing independent of the reference time of the grand master 36) and the delay time on the I3C bus that occurs when transmitting the synchronous information, to the sensor device 23a-1 and the sensor device 23a-2. Therefore, the sensor device 23a-1 and the sensor device 23a-2 transmit, via the I3C bus, the sensing data sensed according to the event trigger a indicating the timing synchronized with the unique reference time of the sensor hub device 22, to the sensor hub device 22.

[0049] On the other hand, the sensor device 23b transmits, via Ethernet, the sensing data sensed according to the event trigger b indicating the timing synchronized with the reference time of the grand master 36 supplied via Ethernet, to the host device 21.

[0050] Thus, in the conventional communication system, while the sensor device 23a-1 and the sensor device 23a-2 output the sensing data according to the event trigger a indicating the timing synchronized with the unique reference time of the sensor hub device 22, the sensor device 23b outputs the sensing data according to the event trigger b indicating the timing synchronized with the reference time of the grand master 36. That is, the timing at which the sensor device 23a-1 and the sensor device 23a-2 output the sensing data and the timing at which the sensor device 23b outputs the sensing data become asynchronous with each other.

[0051] Figure 3 shows an example of a timing chart for communication via the I3C bus by the communication system 11.

[0052] First, from the start of communication via the I3C bus until the sensor hub device 22 sets Async Mode for the host device 21, the process is the same as described with reference to Figure 2.

[0053] Furthermore, in the communication system 11, as described above, the I3C target 32 ​​of the host device 21 can transmit timestamp information (Async timestamp) conforming to the reference time of the grandmaster 36 to the sensor hub device 22 using IBI. As a result, in the communication system 11, the processor 45 of the sensor hub device 22 can estimate the reference time of the grandmaster 36 based on that timestamp information.

[0054] The reference estimated time shown in Figure 3 is the time required for the processor 45 of the sensor hub device 22 to estimate the reference time of the grandmaster 36 based on the timestamp information. The processor 45 then notifies the I3C controller 43 of the reference time of the grandmaster 36 estimated based on the timestamp information via the controller control unit 44. As a result, the I3C controller 43 can transmit synchronization information (ST+DT) based on the reference time of the grandmaster 36 estimated from the timestamp information by the processor 45 to sensor devices 23a-1 and 23a-2 via the I3C bus. Accordingly, sensor devices 23a-1 and 23a-2 transmit sensing data sensed according to event trigger a, which indicates timing synchronized with the reference time of the grandmaster 36 estimated by the processor 45, to the sensor hub device 22 via the I3C bus.

[0055] Meanwhile, the sensor device 23b transmits the sensed data it has sensed to the host device 21 via Ethernet, according to an event trigger b that indicates timing synchronized with the reference time of the grandmaster 36 supplied via Ethernet.

[0056] In this way, in the communication system 11, sensor devices 23a-1 and 23a-2 output sensing data according to event trigger a, which indicates timing synchronized with the reference time of the grandmaster 36 estimated by the processor 45, and sensor device 23b also outputs sensing data according to event trigger b, which indicates timing synchronized with the reference time of the grandmaster 36. In other words, the timing at which sensor devices 23a-1 and 23a-2 output sensing data and the timing at which sensor device 23b outputs sensing data are synchronized with each other according to the reference time of the grandmaster 36.

[0057] The communication system 11 configured as described above can distribute processing on the host device 21 by transferring controller rights from the host device 21 to the sensor hub device 22. Even after controller rights are transferred from the host device 21, the sensor hub device 22 can synchronize sensor devices 23a-1 and 23a-2 to the reference time of the host device 21's grandmaster 36.

[0058] In the I3C communication standard, the sensor data rate, which is the interval of event trigger a generated by the sensor control unit 52a, is limited to be longer than the time from the reference time of the grandmaster 36 to the timing when synchronization information is transmitted (i.e., the delay time DT shown in Figure 3). In addition, in order to synchronize the timing of outputting sensing data between sensor device 23a and sensor device 23b, the sensor data rate of event trigger b is set to match the sensor data rate of event trigger a. That is, the sensor data rate at which sensor devices 23a and 23b output sensing data is set to an interval longer than the delay time DT shown in Figure 3.

[0059] Referring to the flowchart shown in Figure 4, the timing control process in the communication system 11, which controls the output of sensing data in synchronization with the reference time of the grandmaster 36 even after the host device 21 has been set to Async Mode, will be explained.

[0060] In step S11, the host device 21 performs the initial setup of the I3C bus.

[0061] In step S12, the sensor hub device 22 sends a CRR requesting the host device 21 to transfer controller rights.

[0062] In step S13, the host device 21 performs the necessary communication (Role change) to transfer controller rights to the sensor hub device 22.

[0063] In step S14, the sensor hub device 22 performs initial setup of timing control for communication via the I3C bus (transmission of TPH, TU, and ODR) and sets Async Mode for the host device 21.

[0064] In step S15, the host device 21 uses IBI to transmit timestamp information compliant with the reference time of the grandmaster 36 to the sensor hub device 22.

[0065] In step S16, the sensor hub device 22 transmits synchronization information based on the reference time of the grandmaster 36 estimated from the timestamp information to sensor devices 23a-1 and 23a-2 via the I3C bus. As a result, sensor devices 23a-1 and 23a-2 can transmit sensing data sensed according to event trigger a, which indicates timing synchronized with the reference time of the grandmaster 36 estimated by the processor 45, to the sensor hub device 22 via the I3C bus.

[0066] After the processing in step S16, the process returns to step S15, and the same process is repeated until, for example, controller rights are transferred to the host device 21, or until communication via the I3C bus is terminated.

[0067] By performing the timing control processing described above, the communication system 11 can more reliably synchronize between the sensor device 23a, which communicates via the I3C bus, and the sensor device 23b, which communicates via Ethernet.

[0068] <Second Configuration Example of a Communication System> Referring to Figures 5 to 7, a configuration example of a second embodiment of a communication system to which this technology is applied will be described.

[0069] Figure 5 is a block diagram showing an example configuration of a second embodiment of the communication system. In the communication system 11A shown in Figure 5, components common to the communication system 11 shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0070] As shown in Figure 5, the communication system 11A has the same configuration as the communication system 11 in Figure 1, in that it includes a host device 21, sensor device 23a-1, sensor device 23a-2, and sensor device 23b, but it differs from the communication system 11 in that it includes a sensor hub device 22A.

[0071] The sensor hub device 22A has the same configuration as the sensor hub device 22 in Figure 1, comprising a multiplexer 41, an I3C target 42, an I3C controller 43, and a processor 45, but differs from the sensor hub device 22 in that it includes a controller control unit 44A.

[0072] The controller control unit 44A is configured to pre-calculate and store the reference time required to estimate the reference time of the host device 21's grandmaster 36, and to have a reference time processing unit 46 that performs processing to estimate the reference time of the host device 21's grandmaster 36.

[0073] In other words, in the communication system 11A, the reference time processing unit 46 can pre-calculate a reference estimated time, which is the time required to estimate the reference time of the grandmaster 36 based on the timestamp information, and store that reference estimated time. Then, each time timestamp information is supplied from the I3C controller 43, the reference time processing unit 46 estimates the reference time of the grandmaster 36 of the host device 21 based on the timestamp information and notifies the I3C controller 43 of the reference time.

[0074] Furthermore, in the communication system 11A, the processor 37 of the host device 21 can read the reference estimated time held in the reference time processing unit 46 via communication over the I3C bus before controller rights are transferred to the sensor hub device 22A. The processor 37 can then transmit timestamp information (Async timestamp) compliant with the reference time of the grandmaster 36 to the sensor hub device 22A via communication over the I3C bus at an earlier timing than the reference time of the grandmaster 36 by the amount of the reference estimated time.

[0075] As a result, in the sensor hub device 22A, the reference time processing unit 46 can start estimating the reference time of the grandmaster 36 at a timing earlier than the reference time of the grandmaster 36 by the amount of the reference estimation time. Therefore, the sensor hub device 22A can transmit synchronization information to sensor devices 23a-1 and 23a-2 via the I3C bus at a timing earlier by the amount of the reference estimation time, for example, at approximately the same timing as the reference time of the grandmaster 36.

[0076] Thus, the communication system 11A, similar to the communication system 11 in Figure 1, can more reliably synchronize between the sensor device 23a that communicates via the I3C bus and the sensor device 23b that communicates via Ethernet.

[0077] Furthermore, in the communication system 11A, timestamp information is transmitted from the host device 21 at a timing earlier than the reference time of the grandmaster 36 by the amount of the reference estimated time. This shortens the time from the reference time of the grandmaster 36 to the timing when the synchronization information is transmitted (i.e., the delay time DT shown in Figure 6, which will be described later). As a result, the communication system 11A can output event data at a shorter sensor data rate than the communication system 11 in Figure 1.

[0078] Figure 6 shows an example of a timing chart for communication via the I3C bus by the communication system 11A.

[0079] First, when communication via the I3C bus begins, the host device 21 has controller rights and performs the initial setup of the I3C bus. Furthermore, the host device 21 reads the reference estimated time held in the reference time processing unit 46 of the sensor hub device 22A via communication via the I3C bus.

[0080] Subsequently, when the sensor hub device 22A sends a Controller Role Request (CRR) to the host device 21 requesting the transfer of controller rights, the host device 21 performs the necessary communication (Role change) to transfer controller rights to the sensor hub device 22A. As a result, the host device 21 operates as the target device, and the sensor hub device 22A controls communication via the I3C bus as the controller device.

[0081] The sensor hub device 22A, which has controller rights, then transmits TPH (Procedure Repetition Time), which indicates the synchronous communication period, TU (Time Unit), which indicates the time unit, and ODR (Output Data Rate), which indicates the data rate, as initial settings for timing control in communication via the I3C bus. The sensor hub device 22A then sets Async Mode for the host device 21.

[0082] Furthermore, in the communication system 11A, as described above, the I3C target 32 ​​of the host device 21 can use IBI to send timestamp information (Async timestamp) compliant with the reference time of the grandmaster 36 to the sensor hub device 22A at a timing earlier than the reference time of the grandmaster 36 by the amount of the reference estimated time. As a result, in the communication system 11A, the reference time processing unit 46 of the sensor hub device 22A can start estimating the reference time of the grandmaster 36 at a timing earlier than the reference time of the grandmaster 36 by the amount of the reference estimated time, as shown in Figure 6.

[0083] Furthermore, after the estimated reference time has elapsed, the I3C controller 43 can transmit synchronization information (ST+DT) based on the reference time of the grandmaster 36 estimated from the timestamp information by the reference time processing unit 46 to sensor devices 23a-1 and 23a-2 via the I3C bus. Accordingly, sensor devices 23a-1 and 23a-2 transmit the sensing data they sensed according to event trigger a, which indicates timing synchronized with the reference time of the grandmaster 36 estimated by the reference time processing unit 46, to the sensor hub device 22A via the I3C bus.

[0084] Meanwhile, the sensor device 23b transmits the sensed data it has sensed to the host device 21 via Ethernet, according to an event trigger b that indicates timing synchronized with the reference time of the grandmaster 36 supplied via Ethernet.

[0085] In this way, in the communication system 11A, sensor devices 23a-1 and 23a-2 output sensing data according to event trigger a, which indicates timing synchronized with the reference time of the grandmaster 36 estimated by the reference time processing unit 46, and sensor device 23b also outputs sensing data according to event trigger b, which indicates timing synchronized with the reference time of the grandmaster 36. In other words, the timing at which sensor devices 23a-1 and 23a-2 output sensing data and the timing at which sensor device 23b outputs sensing data are synchronized with each other according to the reference time of the grandmaster 36.

[0086] Furthermore, in the communication system 11A, the delay time DT that limits the sensor data rate, which is the interval between event triggers a generated by the sensor control unit 52, can be shortened compared to the delay time DT shown in Figure 3, as shown in Figure 6. Therefore, the communication system 11A can output event data at a shorter sensor data rate than the communication system 11 in Figure 1, enabling, for example, more granular time synchronization. Note that the sensor data rate at which sensor devices 23a and 23b output sensing data is set to an interval longer than the delay time DT shown in Figure 6.

[0087] Referring to the flowchart shown in Figure 7, the timing control process in the communication system 11A, which controls the output of sensing data in synchronization with the reference time of the grandmaster 36 even after the host device 21 has been set to Async Mode, will be explained. In the communication system 11A, the reference time processing unit 46 holds a reference estimated time calculated in advance.

[0088] In step S21, the host device 21 performs the initial setup of the I3C bus.

[0089] In step S22, the host device 21's processor 37 reads the reference estimated time held in the reference time processing unit 46 via communication over the I3C bus.

[0090] In steps S23 to S25, the same process as in steps S12 to S14 in Figure 4 is performed.

[0091] In step S26, the host device 21 transmits timestamp information compliant with the reference time of the grandmaster 36 to the sensor hub device 22 using IBI, at a timing earlier than the reference time of the grandmaster 36 by the amount of the reference estimated time.

[0092] In step S27, the sensor hub device 22A transmits synchronization information based on the reference time of the grandmaster 36 estimated from the timestamp information to sensor devices 23a-1 and 23a-2 via the I3C bus. As a result, sensor devices 23a-1 and 23a-2 can transmit sensing data sensed according to event trigger a, which indicates timing synchronized with the reference time of the grandmaster 36 estimated by the reference time processing unit 46, to the sensor hub device 22A via the I3C bus.

[0093] After the processing in step S27, the process returns to step S26, and the same process is repeated until, for example, controller rights are transferred to the host device 21, or until communication via the I3C bus is terminated.

[0094] By performing the timing control processing described above, the communication system 11A can more reliably synchronize between the sensor device 23a, which communicates via the I3C bus, and the sensor device 23b, which communicates via Ethernet. Furthermore, the communication system 11A has its limitations on the sensor data rate relaxed, and can output sensing data at a shorter sensor data rate.

[0095] <Example of Computer Configuration> Next, the series of processes (communication methods) described above can be performed by hardware or by software. When the series of processes are performed by software, the programs that make up that software are installed on a general-purpose computer or the like.

[0096] Figure 8 is a block diagram showing an example configuration of one embodiment of a computer on which the program that performs the series of processes described above is installed.

[0097] In a computer, the CPU (Central Processing Unit) 101, ROM (Read Only Memory) 102, RAM (Random Access Memory) 103, and EEPROM (Electronically Erasable and Programmable Read Only Memory) 104 are interconnected by a bus 105. An input / output interface 106 is further connected to the bus 105, and the input / output interface 106 is connected to an external device.

[0098] In a computer configured as described above, the CPU 101 loads programs stored in ROM 102 and EEPROM 104 into RAM 103 via bus 105 and executes them, thereby performing the series of processes described above. In addition, programs executed by the computer (CPU 101) can be pre-written to ROM 102, or installed or updated from an external source via input / output interface 106 into EEPROM 104.

[0099] In this specification, the processes performed by a computer according to a program do not necessarily have to be performed chronologically in the order described in the flowchart. That is, the processes performed by a computer according to a program include processes that are executed in parallel or individually (e.g., parallel processing or object-based processing).

[0100] Furthermore, the program may be processed by a single computer (processor), or it may be processed in a distributed manner by multiple computers. Moreover, the program may be transferred to a remote computer for execution.

[0101] Furthermore, in this specification, a system means a collection of multiple components (devices, modules (parts), etc.), regardless of whether all components are located in the same enclosure or not. Therefore, multiple devices housed in separate enclosures and connected via a network, and a single device in which multiple modules are housed in one enclosure, are both considered systems.

[0102] Furthermore, for example, the configuration described as a single device (or processing unit) may be divided and configured as multiple devices (or processing units). Conversely, the configurations described above as multiple devices (or processing units) may be combined and configured as a single device (or processing unit). It is also possible to add configurations other than those described above to the configuration of each device (or each processing unit). Moreover, if the overall system configuration and operation are substantially the same, a part of the configuration of one device (or processing unit) may be included in the configuration of another device (or other processing unit).

[0103] Furthermore, for example, this technology can be configured as cloud computing, where a single function is shared and processed collaboratively by multiple devices via a network.

[0104] Furthermore, for example, the program described above can be executed on any device. In that case, the device should have the necessary functions (such as functional blocks) and be able to obtain the necessary information.

[0105] Furthermore, each step described in the flowchart above can be executed by a single device or shared among multiple devices. Additionally, if a single step includes multiple processes, these processes can be executed by a single device or shared among multiple devices. In other words, multiple processes within a single step can be executed as multiple steps. Conversely, processes described as multiple steps can be combined and executed as a single step.

[0106] Furthermore, the program executed by the computer may be executed in a chronological order according to the sequence of steps described herein, or it may be executed in parallel or individually at necessary times, such as when a call is made. In other words, as long as no inconsistencies arise, the processing of each step may be executed in an order different from the sequence described above. Moreover, the processing of the steps of this program may be executed in parallel with the processing of other programs, or it may be executed in combination with the processing of other programs.

[0107] Furthermore, the technologies described in this specification can be implemented independently, as long as they do not create a contradiction. Of course, any multiple technologies can also be implemented in combination. For example, some or all of the technologies described in one embodiment can be combined with some or all of the technologies described in another embodiment. In addition, some or all of the above-mentioned technologies can be implemented in combination with other technologies not mentioned above.

[0108] <Example of Configuration Combinations> The technology can also take the following configurations: (1) A communication system comprising: a host device which is a main controller device that can communicate using a first communication standard and a second communication standard and takes the lead in controlling communication in the first communication standard; a sensor hub device which normally operates as a target device in the first communication standard and functions as a secondary controller that controls communication in the first communication standard when the controller rights to control communication in the first communication standard are transferred from the host device; a first sensor device which operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device which communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of the grandmaster owned by the host device, wherein the host device transmits timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device, and the sensor hub device transmits synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device. (2) The communication system according to (1) above, wherein the first sensor device outputs the sensing data in synchronization with the reference time of the grandmaster estimated by the sensor hub device based on the synchronization information transmitted from the sensor hub device. (3) The communication system according to (1) or (2) above, wherein the synchronization information includes a synchronization signal for synchronizing timing between devices on the bus and a delay time from the reference time of the grandmaster estimated by the sensor hub device from the timestamp information to the synchronization signal. (4) The communication system according to (3) above, wherein the sensor data rate at which the first sensor device and the second sensor device output the sensing data is set to an interval longer than the delay time.(5) The communication system according to any one of (1) to (4) above, wherein the sensor hub device has a processor that estimates the reference time of the grandmaster based on the timestamp information. (6) The communication system according to any one of (1) to (4) above, wherein the sensor hub device has a reference time processing unit that calculates and stores in advance a reference estimated time which is the time required to estimate the reference time of the grandmaster based on the timestamp information, and estimates the reference time of the grandmaster based on the timestamp information. (7) The communication system according to (6) above, wherein the host device reads the reference estimated time from the reference time processing unit before the controller rights are transferred to the sensor hub device, and transmits the timestamp information to the sensor hub device at a timing earlier than the reference time of the grandmaster by the amount of the reference estimated time, and the sensor hub device receives the timestamp information after the controller rights are transferred from the host device, and starts estimating the reference time of the grandmaster at a timing earlier than the reference time of the grandmaster by the amount of the reference estimated time. (8) The communication system according to (7) above, wherein the sensor hub device transmits the synchronization information to the first sensor device at approximately the same timing as the reference time of the grandmaster. (9) The communication system according to (8) above, wherein the sensor data rate at which the first sensor device and the second sensor device output the sensing data is set to an interval longer than the delay time from the timing according to the reference time of the grandmaster to the timing at which the synchronization information is transmitted on the bus. (10) The communication system according to any one of (1) to (9) above, wherein the first communication standard is MIPI (Mobile Industry Processor Interface) I3C (Improved Inter Integrated Circuits) and the second communication standard is Ethernet.(11) A communication method for a communication system comprising: a host device which is a primary controller device capable of communicating in a first communication standard and a second communication standard and which takes the lead in controlling communication in the first communication standard; a sensor hub device which normally operates as a target device in the first communication standard and functions as a secondary controller that controls communication in the first communication standard when the controller rights for controlling communication in the first communication standard are transferred from the host device; a first sensor device which operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device which communicates with the host device in the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, the communication method comprising: the host device transmitting timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device; and the sensor hub device transmitting synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.(12) A program for causing a computer in a communication system comprising: a host device which is a primary controller device capable of communicating in a first communication standard and a second communication standard and which takes the lead in controlling communication in the first communication standard; a sensor hub device which normally operates as a target device in the first communication standard and, when the controller rights to control communication in the first communication standard are transferred from the host device, functions as a secondary controller that controls communication in the first communication standard as the controller device; a first sensor device which operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device which communicates with the host device in the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, to execute a process including: the host device transmitting timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device; and the sensor hub device transmitting synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

[0109] It should be noted that this embodiment is not limited to the embodiment described above, and various modifications are possible without departing from the spirit of this disclosure. Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also exist.

[0110] 11 Communication system, 21 Host device, 22 Sensor hub device, 23a and 23b Sensor devices, 31 Multiplexer, 32 I3C target, 33 I3C controller, 34 Controller control unit, 35 Ethernet processing unit, 36 Grandmaster, 37 Processor, 41 Multiplexer, 42 I3C target, 43 I3C controller, 44 Controller control unit, 45 Processor, 46 Reference time processing unit, 51 I3C target, 52a and 52b Sensor control unit, 53a and 53b Measurement unit 53, 54 Ethernet processing unit

Claims

1. A communication system comprising: a host device that can communicate using a first communication standard and a second communication standard and is a primary controller device that takes the lead in controlling communication in the first communication standard; a sensor hub device that normally operates as a target device in the first communication standard and, when the controller rights to control communication in the first communication standard are transferred from the host device, functions as a secondary controller that controls communication in the first communication standard as the controller device; a first sensor device that operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device that communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of the grandmaster owned by the host device, wherein the host device transmits timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device, and the sensor hub device transmits synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

2. The communication system according to claim 1, wherein the first sensor device outputs the sensing data in synchronization with the reference time of the grandmaster estimated in the sensor hub device based on the synchronization information transmitted from the sensor hub device.

3. The communication system according to claim 2, wherein the synchronization information includes a synchronization signal for synchronizing timing between devices on the bus, and a delay time from the reference time of the grandmaster estimated from the timestamp information in the sensor hub device to the synchronization signal.

4. The communication system according to claim 3, wherein the sensor data rate at which the first sensor device and the second sensor device output the sensing data is set to an interval longer than the delay time.

5. The communication system according to claim 1, wherein the sensor hub device has a processor that estimates the reference time of the grandmaster based on the timestamp information.

6. The communication system according to claim 1, wherein the sensor hub device pre-calculates and stores a reference estimation time, which is the time required to estimate the reference time of the grandmaster based on the timestamp information, and has a reference time processing unit that estimates the reference time of the grandmaster based on the timestamp information.

7. The communication system according to claim 6, wherein the host device reads the reference estimated time from the reference time processing unit before the controller rights are transferred to the sensor hub device, and transmits the timestamp information to the sensor hub device at a timing earlier than the reference time of the grandmaster by the amount of the reference estimated time, and the sensor hub device receives the timestamp information after the controller rights are transferred from the host device, and starts estimating the reference time of the grandmaster at a timing earlier than the reference time of the grandmaster by the amount of the reference estimated time.

8. The communication system according to claim 7, wherein the sensor hub device transmits the synchronization information to the first sensor device at approximately the same timing as the reference time of the grandmaster.

9. The communication system according to claim 8, wherein the sensor data rate at which the first sensor device and the second sensor device output the sensing data is set to an interval longer than the delay time from the timing according to the reference time of the grandmaster to the timing at which the synchronization information is transmitted on the bus.

10. The communication system according to claim 1, wherein the first communication standard is MIPI (Mobile Industry Processor Interface) I3C (Improved Inter Integrated Circuits), and the second communication standard is Ethernet.

11. A communication method for a communication system comprising: a host device that can communicate using a first communication standard and a second communication standard and is a primary controller device that takes the lead in controlling communication in the first communication standard; a sensor hub device that normally operates as a target device in the first communication standard and, when the controller rights to control communication in the first communication standard are transferred from the host device, functions as a secondary controller that controls communication in the first communication standard as the controller device; a first sensor device that operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device that communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, the communication method comprising: the host device transmitting timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device; and the sensor hub device transmitting synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

12. A program for causing a computer in a communication system comprising: a host device that can communicate using a first communication standard and a second communication standard and is a primary controller device that takes the lead in controlling communication in the first communication standard; a sensor hub device that normally operates as a target device in the first communication standard and, when the host device transfers the controller rights to control communication in the first communication standard, functions as a secondary controller that controls communication in the first communication standard as the controller device; a first sensor device that operates as a target device in the first communication standard and outputs sensing data acquired by sensing; and a second sensor device that communicates with the host device using the second communication standard and outputs sensing data acquired by sensing in synchronization with the reference time of a grandmaster owned by the host device, to execute a process including: the host device transmitting timestamp information conforming to the reference time of the grandmaster to the sensor hub device after transferring the controller rights to the sensor hub device; and the sensor hub device transmitting synchronization information based on the reference time of the grandmaster estimated from the timestamp information to the first sensor device.

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