Communication device and communication method

Abstract

The present disclosure relates to a communication device and a communication method that make it possible to achieve link-up with a communication partner device in a more suitable manner. A communication device according to the present disclosure comprises a communication unit that transmits and receives data to and from a communication partner device, wherein the communication unit detects a startup failure in a startup procedure, and when a startup failure has been detected, changes a communication setting of the own device to a communication setting that can be set in the communication partner device. The present disclosure can be applied, for example, to a communication system in which a vehicle-mounted camera is connected by A-PHY.

Description

Communication Apparatus and Communication Method

[0001] The present disclosure relates to a communication apparatus and a communication method, and particularly relates to a communication apparatus and a communication method that enable realizing link-up with a communication partner apparatus in a more suitable manner.

[0002] In recent years, the A-PHY (The Automotive PHY) standard is known as one of the standards defined by the MIPI (Mobile Industry Processor Interface) Alliance (A-PHY is a registered trademark). A-PHY is a standard for the physical layer of in-vehicle SerDes (Serializer Deserializer).

[0003] Patent Document 1 discloses a technology related to activation of A-PHY security.

[0004] International Publication No. 2020 / 113812

[0005] In A-PHY, if communication settings do not match at startup between a Source and a Sink that transmit and receive data to and from each other, link-up cannot be achieved.

[0006] The present disclosure has been made in view of such circumstances, and enables realizing link-up with a communication partner apparatus in a more suitable manner.

[0007] The communication apparatus of the present disclosure includes a communication unit that transmits and receives data to and from a communication partner apparatus, wherein the communication unit detects a startup failure in a startup procedure, and when the startup failure is detected, changes the communication setting of the own apparatus to the communication setting that can be set in the communication partner apparatus.

[0008] In the communication method of the present disclosure, a communication apparatus that transmits and receives data to and from a communication partner apparatus detects a startup failure in a startup procedure, and when the startup failure is detected, changes the communication setting of the own apparatus to the communication setting that can be set in the communication partner apparatus.

[0009] In this disclosure, a communication device that sends and receives data with a communication partner device is configured such that a startup failure is detected during the startup procedure, and if such startup failure is detected, the communication settings of the device are changed to the communication settings that can be set in the communication partner device.

[0010] This figure shows an overview of a communication system to which the technology related to this disclosure can be applied. This figure shows an overview of the A-PHY startup procedure. This figure explains the downlink communication settings in A-PHY. This figure explains the downlink communication settings in A-PHY. This figure explains the uplink communication settings in A-PHY. This figure shows an example of a downlink startup failure. This figure shows a first example of a change to the downlink communication settings. This figure shows a second example of a change to the downlink communication settings. This figure shows an example of an uplink startup failure. This figure shows another example of an uplink startup failure. This figure shows a first example of a change to the uplink communication settings. This figure shows a second example of a change to the uplink communication settings. This figure explains the data after transitioning to the idle state. This is a block diagram showing an example of a source configuration. This figure explains the state transitions when A-PHY starts up. This is a list showing examples of communication settings that fail to start up on the downlink. This figure shows an example of a transition in the source communication settings on the downlink. This figure shows another example of a transition in the source communication settings on the downlink. This figure shows an example of a transition in the source communication settings on the uplink.

[0011] The following describes the forms for implementing this disclosure (hereinafter referred to as "embodiments"). The explanation will be given in the following order.

[0012] 1. Overview of the communication system 2. A-PHY startup procedure and communication settings 3. Examples of startup failures and communication setting changes in the downlink 4. Examples of startup failures and communication setting changes in the uplink 5. Source configuration and state transitions during A-PHY startup 6. Examples of communication setting transitions

[0013] <1. Overview of the Communication System> Figure 1 is a diagram showing an example configuration of a communication system to which the technology related to this disclosure can be applied.

[0014] The communication system 1 shown in Figure 1 consists of a communication device 10 and a communication device 20. Communication devices 10 and 20 exchange data via a communication channel 30. In communication system 1, data transmission between communication device 10 and communication device 20 is performed via an A-PHY network. A-PHY is a standard defined by the MIPI Alliance as the physical layer of SerDes for automotive applications. Communication devices 10 and 20 send and receive packets to and from each other using A-PHY.

[0015] Of the two communication devices, 10 and 20, one is configured as a communication device for the image sensor mounted on the in-vehicle camera, and the other is configured as a communication device for the ECU (Electronic Control Unit), which is a computer that controls the vehicle.

[0016] The communication device 10 comprises a processing unit 11 and a communication unit 12. The processing unit 11 consists of chips and circuits that perform processing related to PAL (Protocol Adaptation Layer), and a CPU (Central Processing Unit) that controls the operation of each part of the communication device 10. The communication unit 12 consists of chips and circuits that perform processing related to data transmission. The communication unit 12 performs processing related to A-PHY (mainly processing of the PHY layer). The processing unit 11 performs processing related to the upper layer, which is a layer above A-PHY.

[0017] The communication device 20 comprises a processing unit 21 and a communication unit 22. The processing unit 21 consists of chips and circuits that perform PAL-related processing, a CPU that controls the operation of each part of the communication device 20, etc. The communication unit 22 consists of chips and circuits that perform data transmission-related processing. The communication unit 22 performs A-PHY-related processing. The processing unit 21 performs processing related to the upper layer, which is a higher layer than A-PHY.

[0018] In communication system 1, one of the communication devices 10 and 20 acts as the source, and the other as the sink. Transmission from the source to the sink is called downlink, and transmission from the sink to the source is called uplink. Downlink and uplink have different data transmission speeds (communication speeds), with downlink being faster than uplink.

[0019] <2. A-PHY Startup Procedure and Communication Settings> (Outline of A-PHY Startup Procedure) Figure 2 shows an outline of a typical A-PHY startup procedure in the current system.

[0020] As shown in Figure 2, when A-PHY is started, the source and sink transition through states in the following order: Silent state (S), Training state (T), Idle state (I), and Normal state (N). In the source, two training states are defined: a training state without K-sequences and a training state with K-sequences.

[0021] If K-sequences are sent and received in the training state, and in_idle is sent and received in the idle state, and the scrambler is not locked on either the downlink or uplink, the startup procedure shown in Figure 2 will loop (StatUpFailCnt). In other words, in A-PHY, if the communication settings do not match between the source and sink at startup, the link cannot be established.

[0022] (Communication Settings in A-PHY) The communication settings in A-PHY will be explained with reference to Figures 3 to 5. Figure 3 shows the standard downlink communication settings in A-PHY, and Figure 4 shows the optional downlink communication settings in A-PHY. Figure 5 shows the standard uplink communication settings in A-PHY.

[0023] As shown in Figures 3 and 4, seven gears, G1 through G7, are defined for the downlink, with optional gears defined for G1 through G3. Additionally, as shown in Figure 5, three gears, U1 through U3, are defined for the uplink.

[0024] In A-PHY, Gear indicates the data transmission speed, and a modulation scheme is defined for each Gear. In A-PHY, the main modulation schemes used are PAM (Pulse Amplitude Modulation) and NRZ (Non Return to Zero).

[0025] In this way, in A-PHY, the modulation scheme is defined for each gear, which determines the symbol rate (Baud) for each gear. If the symbol rates of the source and sink differ when A-PHY is started, the startup will fail in the training state.

[0026] Furthermore, in A-PHY, the scrambler and descramble must perform an XOR operation using the same value (data). When A-PHY starts, even if the symbol rate is the same for the source and sink, if the modulation scheme (scrambling scheme) is different, the startup will fail in the idle state.

[0027] As described above, when A-PHY is started, the Gear and modulation scheme must match between the source and the sink.

[0028] On the other hand, in E / E architectures such as SDV (Software Defined Vehicle), it is possible to change the vehicle's configuration using wireless communication technologies such as OTA (On The Air). Also, if the source and sink cannot link up due to different communication settings (Gear / modulation method), it is necessary to change the communication settings of one of them. However, when A-PHY is not running, it is not possible to change the source's communication settings from the sink. In order to change the source's communication settings, a control line for sideband signals such as I2C (Inter-Integrated Circuit) or 10BASE-T1S, separate from the A-PHY network, is required.

[0029] In contrast, the technology disclosed herein allows the source side to detect startup failures in the A-PHY startup procedure, and if a startup failure is detected, to change the communication settings on the source side to the communication settings that can be set on the sink side. By matching the communication settings at the time of A-PHY startup to the communication settings selected on the sink side, a more favorable link-up can be achieved without using control lines for sideband signals.

[0030] <3. Examples of Downlink Startup Failures and Changes to Communication Settings> First, we will explain examples of downlink startup failures and examples of changes to communication settings in downlink.

[0031] (Example of startup failure in downlink) Figure 6 shows an example of a startup failure in downlink.

[0032] In the example in Figure 6, during the training state following the silent state, the source fails to perform K-Reflection, which is supposed to respond to a K-sequence received on the uplink with a K-sequence, and is unable to receive in_idle on the uplink. In other words, the startup fails in the training state due to the difference in symbol rates between the source and the sink. In this case, the state returns from the training state to the silent state.

[0033] Although not illustrated, even if the symbol rates are the same for the source and sink, if the scrambling methods are different, startup will fail in the idle state. In this case, the state will revert from the idle state to the silent state.

[0034] (Example of changing communication settings in the downlink) In the technology disclosed herein, if a startup failure is detected in the A-PHY startup procedure in the downlink, the startup procedure can be completed by changing the communication settings on the source side.

[0035] Figure 7 shows a first example of changes to the communication settings in the downlink.

[0036] In the example shown in Figure 7, the default communication setting in the source is "G3 PAM4" (Gear is G3, modulation scheme is PAM4), and the default communication setting in the sink is "G2 PAM4". In this case, because the symbol rates of the source and sink are different, the startup fails in the training state, and the startup procedure loops.

[0037] Therefore, as shown in Figure 7, if a startup failure is detected in the training state, the source communication setting is changed from "G3 PAM4" to "G2 PAM4" when returning to the silent state. This allows the states to transition in the order of training state, idle state, and normal state, completing the startup procedure.

[0038] Figure 8 shows a second example of changes to the communication settings in the downlink.

[0039] In the example shown in Figure 8, the default communication setting in the source is "G4 PAM4," and the default communication setting in the sink is "G5 PAM4." In this case, although the symbol rate is the same for both the source and the sink, the scrambling method is different, causing a startup failure in the idle state and resulting in a startup loop.

[0040] Therefore, as shown in FIG. 8, when a startup failure is detected in the idle state, the communication setting of the source is changed from "G4 PAM4" to "G5 PAM4" when returning to the silent state. Accordingly, the states transition in the order of training state, idle state, and normal state, and the startup procedure can be completed.

[0041] <4. Example of Startup Failure and Communication Setting Change in Uplink> Next, an example of startup failure in the uplink and an example of communication setting change in the uplink will be described.

[0042] (Example of Startup Failure in Uplink)

[0043] FIG. 9 is a diagram showing an example of startup failure in an uplink.

[0044] In the example of FIG. 9, the default communication setting configured at the source is "U1" (Gear is U1), and the default communication setting configured at the sink is "U2". In this case, since the symbol rate is the same between the source and the sink, the state transitions from the training state to the idle state. However, due to the different scrambling schemes, data after transitioning to the idle state becomes NG, and startup fails in the idle state. In this case, the state returns from the idle state to the silent state.

[0045] FIG. 10 is a diagram showing another example of startup failure in an uplink.

[0046] In the example of FIG. 10, the default communication setting configured at the source is "U1" or "U2", and the default communication setting configured at the sink is "U3". In this case, in the training state after the silent state, the source cannot receive the K-sequence. That is, due to the different symbol rates between the source and the sink, startup fails in the training state. In this case, the state returns from the training state to the silent state.

[0047] (Example of changing communication settings in uplink) In the technology according to the present disclosure, when a startup failure in the A-PHY startup procedure is detected in the uplink, the startup procedure can be completed by changing the communication settings on the source side.

[0048] FIG. 11 is a diagram illustrating a first example of changing communication settings in an uplink.

[0049] In the example of FIG. 11, the default communication setting configured at the source is "U2 PAM4" (Gear is U2, modulation scheme is PAM4), and the default communication setting configured at the sink is "U1 NRZ". In this case, although the symbol rate is the same between the source and the sink, the shift amount of data after transitioning to the idle state is different, so startup fails in the idle state and the startup procedure loops.

[0050] Therefore, as shown in FIG. 11, when a startup failure is detected in the idle state, the communication setting of the source is changed from "U2 PAM4" to "U1 NRZ" when returning to the silent state. Accordingly, the states transition in the order of training state, idle state, and normal state, and the startup procedure can be completed.

[0051] FIG. 12 is a diagram illustrating a second example of changing communication settings in an uplink.

[0052] In the example of FIG. 12, the default communication setting configured at the source is "U1 NRZ", and the default communication setting configured at the sink is "U3 PAM4". In this case, since the symbol rate differs between the source and the sink, startup fails in the training state and the startup procedure loops.

[0053] Therefore, as shown in Figure 12, if a startup failure is detected in the training state, the source communication setting is changed from "U1 NRZ" to "U3 PAM4" during the training state sequence. This allows the states to transition in the order of training state, idle state, and normal state, completing the startup procedure without looping.

[0054] Furthermore, not limited to the example in Figure 12, if a startup failure is detected in the training state, the source's communication settings may be changed when returning to the silent state.

[0055] Furthermore, in the example shown in Figure 11, when a startup failure is detected in the idle state, the source communication settings are changed when returning to the silent state. However, it is also possible to change the source communication settings during the idle state sequence.

[0056] As explained with reference to Figure 9, even if the symbol rates are the same for the source and sink, the data after transitioning to the idle state will be invalid, resulting in a startup failure in the idle state. Specifically, if the second byte of data after transitioning to the idle state is not zero-byte data (idle data), the startup will fail in the idle state.

[0057] Now, referring to Figure 13, we will explain the data after the transition to the idle state.

[0058] When transitioning to the idle state, the bit data shift amount for the U2 scrambler becomes 16 bits, and the bit data shift amount for the U1 scrambler becomes 8 bits. Therefore, when descrambling is performed with each communication setting (U2, U1), the communication setting in which the second byte after descrambling becomes zero byte data can be determined to be the sink-side communication setting.

[0059] In other words, as shown in the upper part of Figure 13, if the second byte after descrambling in U2 is zero, and the second byte after descrambling in U1 is not zero, then it can be determined that the sink-side communication setting is "U2 PAM4". Also, as shown in the lower part of Figure 13, if the second byte after descrambling in U2 is not zero, and the second byte after descrambling in U1 is zero, then it can be determined that the sink-side communication setting is "U1 NRZ".

[0060] From the above, if the symbol rate is the same for both the source and the sink, the source's communication settings can be changed during the idle state sequence based on the second byte of data after transitioning to the idle state. The source only needs to have either the U1 descrambler or the U2 descrambler to check the second byte of data after transitioning to the idle state, but it may also have both the U1 and U2 descramblers.

[0061] <5. Source Configuration and State Transitions During A-PHY Startup> (Source Configuration) Figure 14 is a block diagram showing an example of the configuration of the communication section of a source (communication device) that allows the communication settings of the device to be changed if a startup failure is detected during the A-PHY startup procedure.

[0062] The communication unit 100 shown in Figure 14 corresponds, for example, to the communication unit 12 in the communication device 10 in Figure 1, or the communication unit 22 in the communication device 20, and performs A-PHY processing to send and receive data with the communication partner device. The communication unit 100 is configured to include an analog PHY 110 connected to the physical wiring that serves as the communication path, and a processing circuit 120 that decodes and descrambles the received uplink signal and scrambles and encodes the downlink signal to be transmitted.

[0063] The processing circuit 120 includes at least a startup state circuit 121, a decoder 122, a descrambler 123, and a data checker 124.

[0064] The startup state circuit 121 executes the state transitions when A-PHY is started. The decoder 122 decodes the uplink signal from the sink, and the descrambler 123 descrambles the decoded signal (data). The data checker 124 checks the descrambled data. The startup state circuit 121 has a determination circuit 131.

[0065] The determination circuit 131 detects a startup failure in the A-PHY startup procedure. If a startup failure is detected, it changes the communication settings of the source device to the communication settings that can be set in the sink device. If the symbol rate (Baud) is changed due to the change in communication settings, the setting value of the analog PHY 110 (analog PHY setting value) is changed by the analog PHY setting sequencer 140.

[0066] (State transitions during A-PHY startup) Referring to Figure 15, the state transitions during A-PHY startup, which are performed by the startup state circuit 121, will be explained.

[0067] A-PHY's startup process begins in a silent state (state ST1).

[0068] After confirming that the opposing sink is also in a silent state, the system transitions to the training state (state ST2) by outputting training data downlink using the default communication settings (Gear / modulation method). Subsequently, by receiving a K-sequence on the uplink, symbol locking and descrambling are initiated (state ST3).

[0069] If the inability to receive the K-sequence persists for 50ms from the start of startup, the system returns to state ST1, indicating a startup failure. At this time, the uplink communication settings (Gear / modulation method) are changed in the Gear / Modulation determination state (state ST6). Alternatively, the uplink communication settings (Gear / modulation method) may be changed during the sequence in state ST3, assuming that the inability to receive the K-sequence is due to different symbol rates between the source and the sink.

[0070] If a K-sequence is received, after a short period of time, the system will transition to the idle state (state ST4) upon receiving in_idle on the uplink.

[0071] If the in_idle signal cannot be received for 50ms from the start of startup, that is, if the symbol rates of the source and sink are different, the system returns to state ST1, indicating that startup failure has been detected. At this time, in state ST6, the downlink communication settings (Gear / modulation method) are changed.

[0072] If in_idle is received on the uplink, in_idle is transmitted on the downlink. In this case, if the modulation scheme is PAM, the scrambler bit data shift amount is changed to 16 bits, and zero bytes of data are transmitted by performing an XOR operation using the valid bits. Note that the shift amount is not changed if the modulation scheme is NRZ. Also, if the uplink Gear is U2 or U3, the descramble bit data shift amount is changed to 16 bits.

[0073] In this state ST4, if zero bytes of data (idle data) cannot be received, the system returns to state ST1, indicating a startup failure. At this time, in state ST6, the uplink communication settings (Gear / modulation method) are changed. Alternatively, the uplink communication settings (Gear / modulation method) may be changed during the sequence of state ST4 by checking the second byte of data after transitioning to state ST4.

[0074] If `in_idle` is sent, after some time, the system will transition to the normal state (state ST5) upon receiving `in_normal` on the uplink.

[0075] If the inability to receive in_normal persists for 100ms from the start of startup, that is, if the scrambling method is different even though the symbol rate is the same for the source and sink, the system returns to state ST1, indicating that startup failure has been detected. At this point, in state ST6, the downlink communication settings (Gear / modulation method) are changed.

[0076] If in_normal is received on the uplink, sending in_normal on the downlink transitions to state ST5, completing the A-PHY startup procedure.

[0077] Furthermore, if the link goes down or goes to sleep after transitioning to the normal state (state ST5), it is necessary to start A-PHY again. In this case, the communication settings (Gear / modulation method) at the time of transitioning to the normal state should be stored. However, to anticipate the possibility of changing the communication settings after transitioning to the normal state, it may be possible to allow the sink to change to the new communication settings in the register.

[0078] <6. Examples of Communication Settings Transitions> Figure 16 is a list showing examples of communication settings that fail to start up in the downlink.

[0079] The list in Figure 16 shows the source communication settings, including symbol rate, modulation scheme, and encoding scheme, as well as the communication settings that may be set in the sink in the event of startup failure in both the training and idle states.

[0080] For example, if the source's default communication setting is "G3 PAM4" and the downlink fails to start in the training state, it means that the sink's communication setting is set to either "G2 NRZ", "G2 PAM4", or "G1 NRZ". Also, if the source's default communication setting is "G3 PAM4" and the downlink fails to start in the idle state, it means that the sink's communication setting is set to either "G4 PAM8" or "G3 PAM4".

[0081] Therefore, the source code should change (transition) its device's communication settings depending on the state when a startup failure is detected.

[0082] Figure 17 shows an example of the transition of the source communication settings in a downlink.

[0083] In the example shown in Figure 17, the source's default communication setting is set to "G3 PAM4". The default communication setting can be arbitrarily set and selected in the register. Furthermore, in the downlink, setting PAM as the default modulation method can reduce the number of communication setting searches required.

[0084] Currently, if the source's communication settings are in the "G3 PAM4" state, and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication settings will be changed to "G2 PAM4".

[0085] Furthermore, if a startup failure is detected after the source's communication settings have been changed, the communication settings will be changed again.

[0086] In other words, if the source's communication setting is "G2 PAM4" and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication setting will be changed to "G2 NRZ".

[0087] Furthermore, if the source's communication setting is "G2 NRZ" and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication setting will be changed to "G1 NRZ".

[0088] On the other hand, if the source's communication setting is "G3 PAM4" and a predetermined number of startup procedure repetitions due to startup failure are detected in the idle state, the communication setting will be changed to "G4 PAM8".

[0089] Furthermore, if the source's communication setting is "G4 PAM8" and a predetermined number of startup procedure repetitions due to startup failure are detected in the idle state, the communication setting will be changed to "G5 PAM16".

[0090] In this way, the source can change the communication settings of its own device by selecting a candidate communication setting (i.e., a communication setting that can be set in the sink) according to the state and communication settings when a startup failure is detected. Note that the order of transitions of the communication settings shown in Figure 17 may be autonomously selected by the source based on the list in Figure 16, or it may be pre-set.

[0091] Figure 18 shows another example of the transition of the source communication settings in the downlink.

[0092] In the example shown in Figure 18, the source's default communication settings are set to "G5 PAM16," and the communication settings are comprehensively changed.

[0093] In other words, if the source's communication setting is "G5 PAM16" and a predetermined number of startup procedure repetitions due to startup failure are detected during the training state, the communication setting will be changed to "G4 PAM8".

[0094] Next, if the source's communication setting is "G4 PAM8" and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication setting will be changed to "G3 PAM4".

[0095] Furthermore, if the source's communication setting is "G3 PAM4" and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication setting will be changed to "G2 PAM4".

[0096] Furthermore, if the source's communication setting is "G2 PAM4" and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication setting will be changed to "G2 NRZ".

[0097] Furthermore, if the source's communication setting is "G2 NRZ" and a predetermined number of startup procedure repetitions due to startup failures are detected during the training state, the communication setting will be changed to "G1 NRZ".

[0098] Figure 19 shows an example of the transition of the source communication settings in the uplink.

[0099] In the example shown in Figure 19, the source's default communication setting is set to "U1 NRZ".

[0100] Currently, if the source's communication setting is "U1 NRZ" and a predetermined number of startup procedure repetitions due to startup failure are detected during the training state, the communication setting will be changed to "U3 PAM4".

[0101] On the other hand, if the source's communication setting is "U1 NRZ" and a predetermined number of startup procedure repetitions due to startup failure are detected in the idle state, the communication setting will be changed to "U2 PAM4".

[0102] In this way, when A-PHY is restarted after the link has been established due to a change in the source's communication settings, it may start from the default communication settings or from the communication settings used when the link was established.

[0103] As described above, the technology disclosed herein allows the source side to detect a startup failure in the A-PHY startup procedure, and if a startup failure is detected, the communication settings on the source side can be changed to the communication settings that can be set on the sink side. This makes it possible to match the communication settings at the time of A-PHY startup to the communication settings selected on the sink side, enabling a more favorable link-up without using control lines for sideband signals.

[0104] 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. Therefore, multiple devices housed in separate enclosures and connected via a network, and a single device containing multiple modules in one enclosure, are both considered systems.

[0105] Furthermore, embodiments applying the technology described herein are not limited to those described above, and various modifications are possible without departing from the gist of the technology described herein.

[0106] Furthermore, the present disclosure can take the following configurations: (1) A communication device comprising a communication unit that transmits and receives data with a communication partner device, wherein the communication unit detects a startup failure in the startup procedure, and, if the startup failure is detected, changes the communication settings of the device itself to the communication settings that can be set in the communication partner device. (2) The communication device according to (1), wherein the communication settings include a data transmission rate and a modulation scheme. (3) The communication device according to (2), wherein the communication unit changes the communication settings of the device itself when it detects that the startup procedure has been repeated a predetermined number of times due to the startup failure. (4) The communication device according to (3), wherein the communication unit further changes the communication settings of the device itself if the startup failure is detected after the communication settings of the device itself have been changed. (5) The communication device according to (4), wherein the communication unit changes the communication settings of the device itself according to the state in the startup procedure when the startup failure is detected. (6) The communication device according to (5), wherein the communication unit selects a candidate communication setting according to the state and communication setting when the startup failure is detected and changes the communication setting of the device itself. (7) The communication device according to (6), wherein the state when the startup failure is detected is the training state or the idle state. (8) The communication device according to (7), wherein when the startup failure is detected, the communication unit changes the communication setting of the device itself when returning to the silent state, which is the first state of the startup procedure. (9) The communication device according to (7), wherein when the startup failure is detected, the communication unit changes the communication setting of the device itself during the sequence of states when the startup failure is detected. (10) The communication device according to (7), wherein the communication unit changes the communication setting of the device itself based on the second byte of data after transitioning to the idle state. (11) The communication device according to any one of (1) to (10), wherein the communication partner device is the source that sends and receives the data using the communication partner device as the sink.(12) A communication method in which a communication device that sends and receives data with a communication partner device detects a startup failure in the startup procedure, and when the startup failure is detected, changes the communication settings of the device to the communication settings that can be set in the communication partner device.

[0107] 1 Communication system, 10 Communication device, 11 Processing unit, 12 Communication unit, 20 Communication device, 21 Processing unit, 22 Communication unit, 30 Communication channel, 100 Source, 110 Analog PHY, 120 Processing circuit, 121 Startup state circuit, 122 Decoder, 123 Descrambler, 124 Data checker, 131 Judgment circuit, 140 Analog PHY setting sequencer

Claims

1. A communication device comprising a communication unit that transmits and receives data with a communication partner device, wherein the communication unit detects a startup failure in the startup procedure, and if the startup failure is detected, changes the communication settings of the device to the communication settings that can be set in the communication partner device.

2. The communication device according to claim 1, wherein the communication settings include a data transmission speed and a modulation scheme.

3. The communication device according to claim 2, wherein the communication unit changes the communication settings of its own device when it detects that the startup procedure has been repeated a predetermined number of times due to a startup failure.

4. The communication device according to claim 3, wherein the communication unit further modifies the communication settings if a startup failure is detected after the communication settings of the device have been changed.

5. The communication device according to claim 4, wherein the communication unit changes the communication settings of the device in accordance with the state in the startup procedure when the startup failure is detected.

6. The communication device according to claim 5, wherein the communication unit selects a candidate communication setting corresponding to the state and the communication setting when the startup failure is detected, and changes the communication setting of the device itself.

7. The communication device according to claim 6, wherein the state when the startup failure is detected is the training state or the idle state.

8. The communication device according to claim 7, wherein the communication unit changes the communication settings of its own device when it returns to the silent state, which is the first state of the startup procedure, in the event that a startup failure is detected.

9. The communication device according to claim 7, wherein the communication unit, when it detects the startup failure, changes the communication settings of its own device during the sequence of states at the time the startup failure was detected.

10. The communication device according to claim 7, wherein the communication unit changes the communication settings of the device based on the second byte of data after transitioning to the idle state.

11. The communication device according to claim 1, which is a source that transmits and receives data using the communication partner device as a sink.

12. A communication method in which a communication device that sends and receives data with a communication partner device detects a startup failure in the startup procedure, and when such startup failure is detected, changes the communication settings of the device to the communication settings that can be set in the communication partner device.

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