TWI870071B - Hybrid wired communication system combining controller area network (can) and other high speed communication technologies - Google Patents

Abstract

This invention discloses a wired communication system in which one communication medium of the wired communication system consists of two wires. The communication system comprises at least two high-speed communication units that are compatible with the CAN protocol. Each of these high-speed communication units comprises a first CAN transceiver utilized to modulate and transmit, or receive and demodulate CAN protocol signals. The first CAN transceiver does not transmit dominant signals that interfere with high-speed signals when the wired communication system is transmitting high-speed signals. The first CAN transceiver can only transmit signals only after a predetermined time period of time has elapsed since the dominant signaling ceased. The communication system has a default mechanism that allows all communication units connected to the same communication medium to know the start and end times of the transmission of high-speed signals for reception and demodulation. All communication units then release the default mechanism and return to the original CAN mode, awaiting for the appearance of the start of frame of the next signal and the arbitration for the next transmission signal.

Description

Wired communication system that mixes CAN and other high-speed communication technologies

The present invention relates to a communication system, and more particularly to a wired communication system that combines a controller area network (CAN) technology with other high-speed communication technologies.

It is known that CAN is one of the most widely used communication protocols, but the insufficient bandwidth of CAN BUS is its biggest drawback. The insufficient bandwidth makes the subsystems (or nodes) in this communication system lack effective interconnection or intercommunication. When the subsystems cannot exchange information correctly, the problem of communication island will arise. Although the maximum speed of another flexible data rate controller area network (Controller Area Network Flexible Data-Rate, hereinafter referred to as CAN FD) protocol is 8Mbps, it is still a major limitation for the current and future development of electric vehicles. Because the communication system has a high bandwidth utilization rate, that is, the communication channel is almost always in use, it is more likely to have data retransmission problems.

In addition, in the CAN protocol, it is important for the communication system to determine the number of subsystems (such as sensors, controllers or other devices) connected to each interface, because the gateway must process the data sent and received from these subsystems. The number of subsystems mounted under each CAN BUS interface needs to be carefully allocated, and more CAN BUS interfaces need to be added to the gateway. It is also necessary to consider that too high bandwidth utilization will more easily lead to data retransmission problems. As a result, when bandwidth is insufficient and easily fully loaded, the flexibility of expanding the subsystems within the communication system will be limited. In addition, in order to consider the bandwidth of each interface on the gateway, the wiring on the vehicle will be more complicated, requiring more connecting wires and equipment, making the entire system more complex and difficult to manage.

The present invention provides a wired communication system that integrates CAN and other high-speed communication systems, such as OFDM (Orthogonal frequency-division multiplexing, referred to as OFDM): Quadrature Amplitude Modulation (QAM), or Serializer/Deserializer (SerDes), as a solution to the above problem. This solution uses a two-wire system such as twisted pair, power line or coaxial line as a transmission medium, and can simultaneously send and receive CAN (or CAN FD) and other high-speed communication technology messages, which can retain the advantages of CAN BUS in in-vehicle communication and improve the transmission speed. Taking Homeplug AV2 as an example, its transmission rate can be as high as 1Gbps. If a similar bandwidth is used to design a suitable OFDM system and mix it with CAN/CAN FD for in-vehicle communication, the in-vehicle communication architecture can be greatly simplified and the use of in-vehicle wiring harnesses can be reduced, thereby achieving the purpose of reducing costs and improving reliability.

As shown in FIG. 1 , FIG. 1 shows a wired communication system 100 that mixes the controller area network of the present invention with other high-speed communication technologies, that is, the wired communication system 100 mixes high-speed communication unit 1, high-speed communication unit 2, and general CAN communication unit 3 or 3A on the same set of communication media.

Please note that the communication medium of the wired communication system 100 is composed of two wires. The wired communication system 100 of this embodiment is on the same CAN BUS, but this embodiment is not limited to twisted pair, power line, coaxial line and their combination, and the wired communication system 100 includes a high-speed communication unit 1 and a high-speed communication unit 2 that are at least compatible with the CAN protocol; wherein the high-speed communication unit 1 and the high-speed communication unit 2 respectively include: a special first CAN transceiver 10 and another high-speed signal transceiver 20, this high-speed signal transceiver 20 can transmit and receive high-speed signals and has a control signal connection with the CAN transceiver 10, or is connected through a microcontroller unit (MCU), and the high-speed signal transceiver 20 and the first CAN transceiver 10 can operate in coordination. In this embodiment, the high-speed communication unit 1 and the high-speed communication unit 2 respectively have a first CAN controller 11 and an MCU. The first CAN controller 11 and the MCU are coupled to the first CAN transceiver 10 and the high-speed signal transceiver 20 for control. The first CAN controller 11 and the MCU can modulate a digital signal to the first CAN transceiver 10 to send a signal that complies with the CAN protocol, and can also demodulate the digital signal sent by the first CAN transceiver 10.

The special first CAN transceiver 10 is used to modulate and send, or receive and demodulate at least one CAN protocol signal; the high-speed signal transceiver 20 uses a non-CAN protocol and a CAN FD protocol. The high-speed signal transceiver 20 and the first CAN transceiver 10 are directly connected or coupled to the same CAN BUS, and the high-speed signal physical layer rate (PHY layer data rate) of the high-speed signal received and sent is higher than 50M bit/sec. The first CAN transceiver 10 and the high-speed signal transceiver 20 work in coordination, and do not send out dominant signals when sending out high-speed signals to destroy the high-speed signals. In other words, the high-speed signal transceiver 20 can send out signals only after the high-speed communication unit to which it belongs obtains the right to send through the arbitration mechanism of the CAN protocol, and the first CAN transceiver 10 that works in coordination with it does not send out dominant signals for a predetermined period of time. The coupling of the present invention means that the signal to be sent can be sent to the wire, or the signal on the wire can be received through a resistor, capacitor, inductor or other element, and the arbitration mechanism of the signal sending of the wired communication system 100 is maintained the same as the CAN protocol.

In addition, in this embodiment, the general CAN communication unit 3 or 3A can be coupled to the same CAN BUS through the high-speed signal isolator 40 so that the general CAN communication unit 3 or 3A can also work normally. The high-speed signal isolator 40 is used to isolate the high-speed signal on the CAN BUS, and the value of the error counter (not shown) in the CAN communication unit 3 or 3A will not increase due to the high-speed signal transmission. One end of the high-speed signal isolator 40 is coupled to the CAN BUS, and the other end is coupled to the second CAN transceiver 30, or the second CAN controller 50, or the MCU.

Please refer to FIG. 2 , which shows a schematic diagram of a high-speed isolator 40 added to a known CAN communication unit 3. Please note that the CAN communication unit 3 in this embodiment includes a general second CAN transceiver 30 and a second CAN controller 50 or MCU. The high-speed signal isolator 40 is used to isolate the high-speed signal from the same CAN BUS, so that the second CAN transceiver 30 receives the CAN signal and transmits a digital signal to the second CAN controller 50 or MCU to maintain the synchronization of the second CAN controller 50 or MCU, and does not increase the error count of the CAN communication unit 3.

Please refer to FIG. 3 , which shows a schematic diagram of a high-speed isolator 40 added to a known CAN communication unit 3A. Please note that the CAN communication unit 3A in this embodiment includes a second CAN controller 50 or MCU. The difference from the above is that the second CAN transceiver 30 can be separated from the CAN communication unit 3A and combined with the high-speed signal isolator 40, so the high-speed signal isolator 40 can have the function of the second CAN transceiver 30. In this embodiment, the high-speed signal isolator 40 isolates the high-speed signal from the same CAN BUS. The high-speed signal isolator 40 receives the CAN signal and directly outputs a digital signal to the second CAN controller 50 or MCU to maintain the synchronization of the second CAN controller 50 or MCU, and does not increase the error count of the CAN communication unit 3A. This high-speed signal isolator can also be regarded as a special first CAN transceiver.

As shown in FIG. 2 and FIG. 3 , when a high-speed communication unit on the same CAN BUS sends a high-speed signal, the high-speed signal isolator 40 is like a special first CAN transceiver 10, and can know the start and end time of sending the high-speed signal to isolate the signal, so as to prevent the second CAN transceiver 30, or the second CAN controller 50 or the MCU connected thereto from generating an error response; as shown in FIG. 2 or FIG. 3 , one end of the high-speed signal isolator 40 is directly connected or coupled to the same CAN BUS, and the other end thereof is connected or coupled to the second CAN transceiver 30, or the second CAN controller 50 or the MCU.

In addition, in a general second CAN transceiver 30 on the same CAN BUS, the second CAN transceiver 30 will perform preset measures to prevent the second CAN transceiver 30 from mistaking a CAN transmitter in the system for sending an error signal or the first CAN transceiver 10 for generating a receiver error signal when the high-speed signal transceiver 20 sends a signal.

As mentioned above, one way to allow the second CAN transceiver 30 connected to the same CAN BUS to operate normally when the high-speed signal transceiver 20 transmits a signal is to set a high-speed signal isolator 40 between the second CAN transceiver 30 and the CAN BUS, or between the second CAN controller 50 or the MCU and the CAN BUS, to isolate the signal transmitted by the high-speed signal transceiver, and the high-speed isolator 40 sends a specific signal to the general second CAN transceiver 30 connected to it, that is, when the high-speed signal is transmitted, the high-speed signal isolator 40 continues to send another signal that complies with the CAN protocol to the second CAN transceiver 30 coupled to it, so that the second CAN transceiver 30 can maintain synchronization, and its transmission error counter (TX error counter) (not shown) and reception error counter (RX error counter) The error accumulation value in (not shown) will not increase. The special first CAN transceiver 10 will not block the normal CAN signal on the CAN BUS, so that the second CAN transceiver 30 can make a normal response to the CAN signal on the CAN BUS.

The communication system 100 utilizes a preset mechanism. For example, the communication system 100 uses a special coding arrangement of a normal CAN signal. The special first CAN transceiver 10 can predict the time when the high-speed transceiver 20 sends a signal before the high-speed transceiver 20 sends a non-CAN signal, and notify the high-speed transceiver 20 to receive or send a signal. The preset mechanism enables all other communication units connected to the same CAN BUS to know the start and end time of sending a high-speed signal for receiving and demodulating. All communication units then release the preset mechanism and return to the original CAN mode, waiting for the next signal frame to start and the next signal to be sent. As shown in Figures 4 and 5, the CAN BUS transmission message will carry an ID (identifier) to represent the message priority. At the same time, the receiving end can filter information through this ID. The standard CAN format has an 11-bit ID, and the extended CAN format has a 29-bit ID. The extended CAN format has 18 more bits of ID than the standard CAN format. In this embodiment, the default mechanism of the wired communication system 100 utilizes a special coding arrangement. One way of the special coding arrangement is to reserve some special IDs (hereinafter referred to as special IDs) for communication with the high-speed communication unit 1 or the high-speed communication unit 2. Each high-speed communication unit uses a general ID when sending a normal CAN signal, and uses a special ID when sending a high-speed signal. The wired communication system 100 must preset these special IDs, and all special first CAN transceivers 10 and high-speed signal isolators 40 can recognize these special IDs, so that they know that the high-speed communication unit will send a high-speed signal in the future and respond correctly. In this way, it can be ensured that all high-speed signal transceivers 20 will receive and demodulate the high-speed signals sent to the CAN BUS, and the general second CAN transceiver 30 will not receive these high-speed signals and cause errors. Since the ID is used for identification, the system is still compatible with the existing CAN and CAN FD protocol signal formats, and the currently known CAN BUS system does not need to be updated and can continue to be used.

In one embodiment, the fields of the standard CAN format of FIG. 4 are, in order, Start of Frame (SOF), 11 bits Identifier (ID), single remote transmission request (RTR), Identifier Extension (IDE), Reserved bit (R0), Data Length Code (DLC), 0~8 bytes Data, cyclic redundancy check (CRC), acknowledgment code (Ack), End of Frame (EOF), Interframe Space (IFS); wherein 0~8 bytes Data can transmit up to 64 bits of data, and DLC is 4 bits in length, and IFS is 7 bits in length, and the IDE of this embodiment indicates that the standard CAN identifier without extension is being transmitted. In order to maintain the usage habits of the standard CAN format as much as possible, the time for high-speed signal transmission is limited to the available period of the data area (DATA field) and the cyclic redundancy check area (CRC field). The wired communication system 100 should preset different DLC values to determine how long the corresponding high-speed signal will be sent. The high-speed signal transmission mainly uses the sum of the time of the data area plus the cyclic redundancy check area. Then, after the high-speed signal transmission is completed, the wired communication system will reserve the high-speed signal receiver of the high-speed communication unit for demodulation and CRC check time in advance. The special first CAN transceiver 10 in the high-speed communication unit that receives the high-speed signal will respond to the ACK, End of Frame (EOF) and Interframe Space (IFS) in the normal CAN format after the high-speed signal transmission is completed, and then the system returns to the normal CAN mode. The high-speed signal contains data and CRC check code. If the CRC verification is wrong, the error flag in the CAN format is still used to respond. Please note that the data area in Figure 4 is 0~8 bytes DATA.

Next, please refer to FIG. 5 . The fields of the extended CAN format in FIG. 5 are SOF, 11 bits ID, Substitute Remote Request (SRR), IDE, 18 bits ID, RTR, reserved bits R0 and R1, Data Length Code (DLC), 0~8 bytes Data, cyclic redundancy check (CRC), acknowledgment code (Ack), End of Frame (EOF), Interframe Space (IFS). Among them, the IDE of this embodiment indicates that there are more identification code bits behind it, and the 18-bit extended code bits are after the IDE. In order to maintain the usage habits of extended CAN as much as possible, the time for high-speed signal transmission is still limited to the available interval of the data area and the cyclic redundancy check area. The wired communication system 100 must first preset different DLC values to determine how long the corresponding high-speed signal will be transmitted. Its high-speed signal transmission mainly uses the total time of the data area plus the cyclic redundancy check area. Then, after the high-speed signal transmission is completed, the wired communication system will reserve the high-speed signal receiver of the high-speed communication unit for demodulation and CRC check time in advance, so that its special first CAN transceiver 10 can respond to ACK/EOF/IFS and return to normal CAN mode. The high-speed signal contains data and CRC check code. If the CRC verification is wrong, the CAN format error flag is still used to respond. Please note that the data area in Figure 4 is 0~8 bytes DATA.

Please note that the high-speed signal transceiver 20 can transmit and receive OFDM signals, QAM signals or some SerDes signals, and will only transmit signals after the high-speed communication unit to which it belongs obtains the transmission right and its special first CAN transceiver 10 stops transmitting signals.

As mentioned above, in Figures 4 and 5, SOF marks the beginning of a new data format. The Arbitration Field contains multiple subsystems (nodes) of the network and is used to determine that when multiple nodes attempt to transmit at the same time, the node with a lower arbitration ID has priority. Other nodes will suspend transmission. The control area is used to control and manage data transmission. The high-speed communication unit can normally send and receive general CAN format signals, but when a special encoding method is recognized and high-speed signals need to be sent, the data area and cyclic redundant code area can be used for high-speed signal transmission and reception. The high-speed signal transmission content already contains the verification code, so there is no need Transmit using low-speed CAN format. After the high-speed signal is sent, it will be retained for a period of time for the high-speed signal transceiver 20 to demodulate and then be opened to other nodes for sending confirmation. The confirmation area is used to represent confirmation information. If the high-speed communication unit cannot demodulate the high-speed signal normally due to interference or other reasons, the sender of the high-speed signal can know through the confirmation code or the error flag sent by the receiver and retransmit; the receiver may also The next time the priority is obtained, the original sender is notified to resend the original packet or directly discard the original packet; when the original packet is resent, the sender can be required to send it in CAN mode or high-speed mode depending on the situation.

Except for the data area and the cyclic redundancy check area, each area can use the original CAN BUS message for transmission, thereby retaining the advantages of CAN. It can also be compatible with the current CAN BUS original equipment by adding a high-speed signal isolator.

To comply with the standard CAN/CAN FD format and the extended CAN/CAN FD format, if only the data area and the cyclic redundancy check area are used to transmit high-speed communication data, the upper limit of the time ratio occupied by high-speed transmission is about 70%. If the time ratio of high-speed transmission is to be further increased, another encoding method can be used to declare a longer continuous transmission time (for example, 1 millisecond (ms)), that is, to extend the time by the sum of the normal data area and the cyclic redundancy check area. Without calculating the bit stuffing time, the upper limit of the extension time is about 80 microseconds (µs). The special first CAN transceiver 10 and its first CAN controller 11 can deliberately ignore the timeout error, and because the high-speed communication unit usually has a crystal oscillator circuit or even a built-in digital controlled crystal oscillator (DCXO), it can still maintain an accurate clock after a long time without losing synchronization, so this special format is allowed. However, during this period of time, the high-speed signal isolator 40 must also maintain the synchronization of the general second CAN transceiver 30 connected to it and the error count does not increase. Therefore, the high-speed signal isolator 40 must always send a false EOF to the general second CAN transceiver 30 connected to it within a reasonable time. Then the high-speed signal isolator 40 continues to send out SOF and sends out a high-priority ID to the second CAN transceiver 30 connected thereto, thereby preventing the second CAN transceiver 30 connected thereto from getting the priority and sending out a signal during this period of time.

Please note that the high-speed communication unit or high-speed signal isolator can use a special ID to identify the special mode of sending high-speed signals for a long time. When the special ID is used, the content in the control field can be repeatedly used to identify the next long-term continuous high-speed signal to be sent, and how much time the continuous high-speed signal will occupy the CAN BUS. The high-speed isolator 40 can limit the general second CAN transceiver 30 accordingly. Please note that in the standard CAN format, the control field is the field IDE, r0, and DLC; in the extended CAN format, the control field is the field r1, r0, and DLC.

Please note that if the time for which the wired communication system 100 continuously transmits high-speed signals exceeds the sum of the time of the data area plus the cyclic redundancy check area, the high-speed signal isolator 40 will continue to send another signal that complies with the CAN protocol to the second CAN transceiver 30 or the second CAN controller 50 connected thereto, so that the second CAN transceiver 30 or the second CAN controller 50 can maintain synchronization with the wired communication system 100 and the error count will not increase, and all communication units can participate in the next arbitration when the frame start (SOF) of the wired communication system 100 appears next time.

In another embodiment, the DLC in the control area is reused. The original DLC is used to indicate the data length of the transmitted message (4 bits encoding). By changing the encoding definition, this encoding can be used to indicate how much time the long-term high-speed signal mode needs to occupy the CAN BUS. In this way, the effective data volume can be greatly increased (for example, the proportion of time occupied by the low-speed CAN format is reduced to less than 5%), and after the transmission is completed, it can return to the original CAN mode to process the CAN signal transmission. This embodiment still inherits the advantage of the CAN protocol of more transmissions. When the high-speed signal is 100MHz bandwidth to transmit OFDM signals, if the resolution of each sub-carrier tone is 10 bits, it means that the wired communication system 100 can reach a physical layer rate (PHY rate) close to 1Gbps, that is, the rate of 1000base-T Ethernet, but it can still maintain the many-to-many network architecture advantage of the CAN protocol and be compatible with the old CAN system. Compatibility with the CAN system is very important for many automotive component manufacturers, and it can be upgraded painlessly without major modifications to the original software and hardware. In the normal high-speed transmission mode, the format of the control area in the signal of the wired communication system 100 is maintained the same as the signal of the CAN protocol; and in the long-term high-speed transmission mode, the format of the control area is maintained the same as the signal of the CAN protocol. The wired communication system 100 redefines the time required for the high-speed signal in the control area field to achieve transmission time extension.

Please refer to FIG. 6. If the wired communication system needs to have a high-speed communication function and is compatible with the general CAN communication unit 3, and the original circuit structure of the CAN communication unit 3 is not changed, that is, the aforementioned high-speed signal isolator is not set. In one embodiment, a high-frequency communication signal is sent when the recessive bit is on, and the amplitude of the high-speed signal is relatively smaller than the amplitude of the dominant bits signal sent by the general CAN communication unit 3, and is maintained at around the middle potential of the CAN BUS, so that the CAN communication unit 3 will not judge it as having a dominant bit. bit) before sending it out; that is, the CAN communication unit 3 will not lose synchronization or increase the number of the built-in error counter due to the operation of the high-speed communication unit 1 or the high-speed communication unit 2. The high-speed communication unit 1 or the high-speed communication unit 2 can still cooperate with the first CAN transceiver 10 to which it belongs, and send a high-speed signal during the time when the first CAN transceiver 10 sends the recessive bit. Moreover, the amplitude of this high-speed signal is smaller than the amplitude of the dominant bit signal sent by the CAN communication unit 3, and will not cause the CAN communication unit 3 to judge it as a dominant bit. A feasible specific method is described as follows: When the high-speed communication unit 1 or 2 has obtained the CAN BUS priority in the arbitration area through the ID, the special first CAN transceiver 10 sends a dominant bit after sending five recessive bits in the data area, so as to avoid the general CAN communication unit 3 from misjudging the bit stuffing error. As shown in the schematic diagram of FIG7, five recessive bits are superimposed on the high-speed signal, and the high-speed signal is sandwiched with the real data to be transmitted, and the high-speed signal is sent in the recessive bit sending interval of the special first CAN transceiver 10. In addition, the high-speed communication unit 1 or 2 has the function of adjusting the signal strength of the high-speed signal to avoid the general CAN communication unit 3 from misjudging the CAN BUS status due to the high-speed signal.

Please refer to Figure 8, which shows another embodiment of the present invention. The wired communication system 800 has a non-high-speed communication unit 4, and the non-high-speed communication unit 4 has a first CAN transceiver 10. The non-high-speed communication unit 4 is connected or coupled to the same set of CAN BUS through the first CAN transceiver 10, and the non-high-speed communication unit 4 does not have a high-speed signal transceiver; in other words, the non-high-speed communication unit 4 does not transmit high-speed signals and can also use the first CAN transceiver 10 directly on the CAN BUS.

In summary, the present invention provides a wired communication system that integrates CAN and other high-speed communication systems, and can simultaneously send and receive messages of CAN (or CAN FD) and other high-speed communication technologies, thereby retaining the advantages of CAN BUS in in-vehicle communication and improving the transmission speed.

100, 800: Wired communication system

1, 2: High-speed communication unit

3. 3A: CAN communication unit

4: Non-high-speed communication unit

10: First CAN transceiver

11: First CAN controller

20: High-speed signal transceiver

30: Second CAN transceiver

40: High-speed signal isolator

50: Second CAN controller

MCU: Microcontroller Unit

[Figure 1] shows the mixing of high-speed communication units and general CAN communication units on the same CAN BUS. [Figure 2] shows a schematic diagram of adding a high-speed isolator to an old CAN communication unit, when the original CAN transceiver cannot be replaced by another special CAN transceiver. [Figure 3] shows a schematic diagram of adding a high-speed isolator to an old CAN communication unit, when the original CAN transceiver can be replaced by another special CAN transceiver. [Figure 4] Standard CAN format and the range used by high-speed communication signals. [Figure 5] Extended CAN format and the range used by high-speed communication signals. [Figure 6] shows the mixing of high-speed communication units and general CAN communication units on the same CAN BUS (without high-speed signal isolators). [Figure 7] shows the CAN signal schematic diagram of Figure 6. [Figure 8] shows another embodiment of the present invention.

100: Wired communication system

1, 2: High-speed communication unit

3. 3A: CAN communication unit

10: The first CAN transceiver

11: First CAN controller

20: High-speed signal transceiver

30: Second CAN transceiver

40: High-speed signal isolator

50: Second CAN controller

MCU: Microcontroller Unit

Claims (12)

A wired OFDM communication system, wherein a communication medium of the wired OFDM communication system is composed of two wires, and the wired OFDM communication system includes at least two high-speed communication units compatible with the CAN protocol, each of which includes: a first CAN transceiver for modulating and sending, or receiving and demodulating CAN protocol signals; wherein, because the wired OFDM communication system has a preset mechanism, the preset mechanism enables all communication units connected to the same communication medium to know the transmission of high-speed signals; The start and end time of the signal are used for reception and demodulation; the first CAN transceiver can not send a dominant signal according to the preset mechanism when the wired OFDM communication system sends a high-speed signal to destroy the high-speed signal; the first CAN transceiver can send a signal after a predetermined period of time after not sending a dominant signal according to the preset mechanism; and all communication units then release the preset mechanism and return to the original CAN mode, waiting for the next signal frame to start and the arbitration of the next signal transmission. The wired OFDM communication system as described in claim 1, wherein the high-speed communication units include: a high-speed signal transceiver, using a non-CAN protocol and a CAN FD protocol, the high-speed signal transceiver and the first CAN transceiver are directly connected or coupled to the same communication medium, and the high-speed signal physical layer rate (PHY layer data rate) of the high-speed signal received and transmitted is higher than 50M bit/sec; and a first CAN controller and an MCU coupled to the first CAN transceiver and the high-speed signal transceiver for control, the first CAN controller and the MCU can modulate digital signals to the first CAN transceiver to send signals that comply with the CAN protocol, and can also demodulate digital signals sent by the first CAN transceiver; wherein the first CAN transceiver and the high-speed signal transceiver operate in coordination, and the first CAN transceiver does not send a dominant signal when the high-speed signal transceiver sends a high-speed signal to destroy the high-speed signal. A wired OFDM communication system as described in claim 2, wherein the arbitration mechanism for signal transmission of the wired OFDM communication system remains the same as the CAN protocol. A wired OFDM communication system as described in claim 2, wherein the wired OFDM communication system includes a CAN communication unit and the CAN communication unit is not the high-speed communication unit. A wired OFDM communication system as described in claim 2, wherein the high-speed communication unit can transmit and receive at least one CAN or CAN FD protocol signal, or transmit and receive at least one high-speed signal to increase the communication speed. A wired OFDM communication system as described in claim 5, wherein the format of a control region in a signal of the wired OFDM communication system is maintained the same as that of a signal of the CAN protocol when in a normal high-speed transmission mode; and the format of the control region in a signal of the long-term high-speed transmission mode is maintained the same as that of a signal of the CAN protocol, and the wired OFDM communication system redefines the time required for the high-speed signal in the control region field to achieve transmission time extension. A wired OFDM communication system as described in claim 5, wherein the high-speed signal transmission mainly utilizes the time sum of a data field and a cyclic redundancy check field (CRC field); the wired OFDM communication system reserves sufficient time for the high-speed communication unit to demodulate after the high-speed signal transmission is completed, and then allows the first CAN transceiver to reply with an acknowledgment (ACK); if the high-speed communication unit cannot demodulate the high-speed signal normally due to interference or other reasons, the sending end of the high-speed signal can use an acknowledgment code, or the sending end can send an error flag (error) from the receiving end. flag) and retransmit; the receiving end may also notify the original sender to resend the original packet or directly discard the original packet when it obtains priority next time, depending on the situation; the resending of the original packet can require the sender to send it in CAN mode or high-speed mode depending on the situation. The wired OFDM communication system as described in claim 4, wherein the CAN communication unit comprises: a high-speed signal isolator for isolating the high-speed signal on the communication medium; a second CAN transceiver coupled to the other end of the high-speed signal isolator and coupled to the communication medium through the high-speed signal isolator for normal operation, and an error counter (error The value of the high-speed signal counter will not increase due to the high-speed signal transmission on the communication medium; and when the high-speed signal is transmitted, the high-speed signal isolator continuously sends another signal that complies with the CAN protocol to the second CAN transceiver coupled to it to maintain synchronization; and a second CAN controller is coupled to the second CAN transceiver to control the second CAN transceiver; Wherein, the high-speed signal isolator can obtain the start and end time of the high-speed communication signal transmitted on the communication medium to perform signal isolation, so as to prevent the second CAN transceiver or the second CAN controller connected to it from generating an error response. A wired OFDM communication system as described in claim 5, wherein the wired OFDM communication system includes a non-high-speed communication unit having the first CAN transceiver and connected or coupled to the same communication medium through the first CAN transceiver, and the non-high-speed communication unit does not have the high-speed signal transceiver. A wired OFDM communication system as described in claim 6, wherein when the time of continuously transmitting high-speed signals exceeds the sum of the time of the data area plus the cyclic redundancy check area, the high-speed signal isolator will continue to send another signal that complies with the CAN protocol to the second CAN transceiver or the second CAN controller connected thereto, so that the second CAN transceiver or the second CAN controller can maintain synchronization with the wired OFDM communication system and the error count does not increase, and all communication units can participate in the next arbitration when the frame start (SOF) of the wired OFDM communication system appears next time. A wired OFDM communication system as described in claim 3, wherein at least one CAN communication unit is connected to the communication medium, wherein the CAN communication unit will not lose synchronization or increase the number of the built-in error counter due to the operation of the high-speed communication unit; the high-speed communication unit can still cooperate with the first CAN transceiver to send a high-speed signal during the time when the first CAN transceiver sends a recessive bit, and the amplitude of the high-speed signal is smaller than the amplitude of the dominant bit signal sent by the CAN communication unit, and will not cause the CAN communication unit to judge it as a dominant bit. A wired OFDM communication system as described in claim 6, wherein the high-speed communication unit uses a first ID when sending a normal CAN signal and uses a second ID when sending a high-speed signal; the first CAN transceiver uses the second ID to determine whether the signal is a general high-speed transmission mode or a long-term high-speed transmission mode.

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