An extended communication device and method for DoIP diagnostics

Abstract

This invention discloses an extended communication device and method for DoIP diagnostics. The device includes a USB module, an MCU module, an Ethernet module, and a diagnostic connector module. The USB module receives diagnostic data and control parameters from a diagnostic device and transmits the diagnostic data and control parameters to the MCU module. The MCU module responds to the control parameters by transmitting the diagnostic data to the diagnostic interface of the vehicle under test via the Ethernet module and the diagnostic connector module. The diagnostic connector module receives DoIP data sent by the diagnostic interface of the vehicle under test and transmits the DoIP data to the MCU module via the Ethernet module. The MCU module also forwards the DoIP data to the diagnostic device via the USB module.

Description

Technical Field

[0001] This invention relates to the field of DoIP diagnostic technology, and more particularly to an extended communication device and method for DoIP diagnostics. Background Technology

[0002] DoIP (Diagnosis over Internet Protocol) is a diagnostic protocol based on the Internet Protocol. It is a communication standard that allows for efficient diagnostics, programming, and software updates of modern vehicles via Ethernet. Therefore, DoIP is a "highway-level" diagnostic protocol that inevitably emerged in the era of intelligent vehicles to resolve the fundamental contradiction between "massive software data" and "traditional low-speed diagnostics." Today, more and more vehicle models are abandoning traditional diagnostic protocols and instead supporting only DoIP protocol diagnostics. However, some older diagnostic equipment does not support DoIP diagnostics, and many diagnostic manufacturers provide overly complex or nonexistent extension solutions for their released equipment.

[0003] Currently, the main solution for expanding DoIP on the market involves three accessories: a USB to Ethernet adapter, a network cable, and a diagnostic male to Ethernet / diagnostic female adapter cable. Performing DoIP diagnostics requires connecting an external USB to Ethernet adapter to the device, then connecting a network cable from the device's Ethernet port to the adapter cable's Ethernet port. Additionally, the diagnostic port of the device needs to be connected to the adapter cable's female connector to provide the activation signal required for DoIP diagnostics. This adds extra steps, including the USB to Ethernet adapter, network cable, and diagnostic male to Ethernet / diagnostic female adapter cable, making the expansion solution cumbersome and inconvenient to implement. Summary of the Invention

[0004] The purpose of this invention is to propose an extended communication device and method for DoIP diagnosis, which aims to solve the problem that existing extended solutions for DoIP are cumbersome and difficult to implement.

[0005] To achieve one, some, or all of the above objectives, or other objectives, in a first aspect, the present invention proposes a DoIP diagnostic method, applied to an extended communication device for DoIP diagnostics, the device comprising a USB module, an MCU module, an Ethernet module, and a diagnostic connector module, including: When sending diagnostic data to the vehicle under test, the diagnostic data and control parameters sent by the diagnostic device are received through the USB module, and the diagnostic data and control parameters are transmitted to the MCU module so that the MCU module responds to the control parameters to control the diagnostic connector module to wake up the DoIP function of the vehicle under test. The diagnostic data is encoded into differential signal form through the Ethernet module and transmitted to the diagnostic interface of the vehicle under test through the Ethernet module. When the vehicle under test sends DoIP data for diagnostic data, the MCU module controls the diagnostic connector module to transmit the DoIP data through the Ethernet module. The MCU module controls the Ethernet module to decode the received differential signal DoIP data into digital signal form, and forwards the digital signal DoIP data to the diagnostic device through the USB module.

[0006] Optionally, the step of controlling the diagnostic connector module to wake up the DoIP function of the vehicle under test includes: Based on the control parameters, the diagnostic function of the vehicle under test is activated by the transistor switching circuit in the diagnostic connector module, so that the diagnostic connector module receives the DoIP data sent by the diagnostic interface of the vehicle under test, and transmits the DoIP data to the MCU module through the Ethernet module.

[0007] Optionally, the method further includes: When sending diagnostic data to the vehicle under test, the digital signal received through the digital interface is encoded into an analog differential signal by the Ethernet physical layer chip, and the analog differential signal is converted into an analog differential network cable signal by the analog differential interface in the Ethernet module, so as to transmit the diagnostic data to the diagnostic interface of the vehicle under test through the Ethernet module. When the vehicle under test sends DoIP data for diagnostic data, the analog differential signal received through the analog differential interface is decoded into a digital signal by the Ethernet physical layer chip.

[0008] On the other hand, the present invention provides an extended communication device for the DoIP diagnostic method, the device comprising: a USB module, an MCU module, an Ethernet module, and a diagnostic connector module; The USB module is used to receive diagnostic data and control parameters from the diagnostic device and transmit the diagnostic data and control parameters to the MCU module. The MCU module is used to respond to the control parameters to control the diagnostic connector module to wake up the DoIP function of the vehicle under test, and to encode the diagnostic data into differential signal form and transmit it to the diagnostic interface of the vehicle under test through the Ethernet module. The diagnostic connector module is used to receive DoIP data sent by the diagnostic interface of the vehicle under test, and transmit the DoIP data to the MCU module through the Ethernet module; The MCU module is also used to control the diagnostic connector module to transmit DoIP data through the Ethernet module. The MCU module decodes the received differential DoIP data into digital signal form and forwards the digital DoIP data to the diagnostic device through the USB module.

[0009] Optionally, the MCU module includes: a main control chip, a filtering circuit, an RC reset circuit, a clock circuit, a flash memory chip, and an Ethernet interface. The filtering circuit filters the input current of the main control chip. The RC reset circuit is connected to the reset pin of the main control chip, enabling the main control chip to reset when the RC reset circuit provides a low level. The clock circuit provides a reference clock for the main control chip. The flash memory chip is connected to the main control chip via a storage interface circuit based on a flexible synchronous controller, allowing the main control chip to store data in the flash memory chip. An integrated MAC layer enables the main control chip to interact with the Ethernet module via the Ethernet interface.

[0010] Optionally, the USB module includes: a VBUS voltage divider detection circuit, a USB ESD protection circuit, and a Type-C interface circuit; wherein, the VBUS voltage divider detection circuit is used to power the diagnostic device, and the voltage divider node in the VBUS voltage divider detection circuit is connected to the ADC pin of the main control chip in the MCU module so that the MCU module can determine the working status of the USB module; the VBUS voltage divider detection circuit is connected to the ESD protection chip in the USB ESD protection circuit, and the ESD protection chip is also connected to the USB differential signal; in the Type-C interface circuit, the power supply pin on the Type-C interface chip is connected in parallel with the VBUS voltage divider detection circuit to power the diagnostic device, the ground pin on the Type-C interface chip is connected in parallel with ground, and the differential data pin on the Type-C interface chip is used to receive diagnostic data and control parameters sent by the diagnostic device, and input the diagnostic data and control parameters into the ESD protection chip as a USB differential signal, and the ESD protection chip transmits the diagnostic data and control parameters to the MCU module.

[0011] Optionally, the Ethernet module includes an Ethernet physical layer chip, a power supply and reference circuit, a bias reference circuit, a crystal oscillator circuit, a reset circuit, and a digital interface. The power supply and reference circuit supplies power to the analog and digital circuits within the Ethernet physical layer chip. The bias reference circuit provides internal bias current to the Ethernet physical layer chip. The crystal oscillator circuit provides a reference clock to the Ethernet physical layer chip. The reset circuit resets the Ethernet physical layer chip. The Ethernet physical layer chip interacts with the MCU module via the digital interface. The Ethernet module also includes an analog differential interface, which converts the analog differential signal output by the Ethernet physical layer chip into an analog differential network signal to transmit the diagnostic data to the diagnostic interface of the vehicle under test via the Ethernet module. The Ethernet physical layer chip encodes the digital signal received through the digital interface into an analog differential signal and decodes the analog differential signal received through the analog differential interface into a digital signal.

[0012] Optionally, the device further includes a power supply circuit for supplying power to the USB module, MCU module, Ethernet module, and diagnostic connector module, respectively. The power supply circuit includes an input circuit, a power supply expansion circuit, a first step-down circuit, a second step-down circuit, and a VBUS power supply circuit. The input circuit filters the vehicle power supply to obtain a stable voltage. The power supply expansion circuit decouples the stable voltage to provide a low-impedance power supply to the first step-down circuit. The first step-down circuit steps down the low-impedance power supply to obtain a 5V regulated power supply. The second step-down circuit steps down the 5V regulated power supply to obtain a 3.3V regulated power supply. The VBUS power supply circuit supplies power to the USB module.

[0013] Optionally, the VBUS power supply circuit includes a switching circuit composed of transistors and MOSFETs, which is used to control the output voltage of the VBUS power supply circuit.

[0014] Optionally, the diagnostic connector module includes a diagnostic socket, an ESD four-channel protection array, a relay, and a transistor switching circuit. The diagnostic socket connects to the diagnostic interface of the vehicle under test (VAT) for data interaction. The ESD four-channel protection array protects the OBD bus within the diagnostic interface. The relay switches between CAN bus transmission and Ethernet signal transmission. The transistor switching circuit wakes up the diagnostic function of the VAT, enabling the diagnostic connector module to receive DoIP data sent by the VAT's diagnostic interface and transmit the DoIP data to the MCU module via the Ethernet module.

[0015] The embodiments of the present invention have the following beneficial effects: This invention enables diagnostic devices that previously did not support the DoIP protocol to perform diagnostics via DoIP. For automotive mechanics, this saves them the cost of purchasing new equipment. For diagnostic device manufacturers, it enhances the scalability of their devices and improves the product ecosystem. Furthermore, compared to traditional solutions that use three peripherals—USB to Ethernet, Ethernet cable, and diagnostic male to female connector—to extend the DoIP protocol, this invention integrates a USB module, an MCU module, an Ethernet module, and a diagnostic connector module. This results in a more compact and smaller device with simpler connections, making it more convenient for users and saving costs for manufacturers. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] in: Figure 1 This is a flowchart of a DoIP diagnostic method provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an extended communication device for DoIP diagnostics provided in an embodiment of this application; Figure 3 This is a circuit schematic diagram of an MCU module in an extended communication device for DoIP diagnostics provided in an embodiment of this application; Figure 4 This is a circuit schematic diagram of a USB module in an extended communication device for DoIP diagnostics provided in an embodiment of this application; Figure 5 This is a circuit schematic diagram of an Ethernet module in an extended communication device for DoIP diagnostics provided in an embodiment of this application; Figure 6 This is a circuit diagram of the power supply module in an extended communication device for DoIP diagnostics provided in an embodiment of this application; Figure 7 This is a circuit diagram of a diagnostic connector module in an extended communication device for DoIP diagnostics, provided in an embodiment of this application. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0019] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0020] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0021] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [the described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [the described condition or event] is detected," or "in response to detection of [the described condition or event]."

[0022] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0024] like Figure 1As shown, this invention provides a DoIP diagnostic method and an extended communication device for DoIP diagnostics. The device includes a USB module, an MCU module, an Ethernet module, and a diagnostic connector module, comprising: S101. When sending diagnostic data to the vehicle under test, the diagnostic data and control parameters sent by the diagnostic device are received through the USB module, and the diagnostic data and control parameters are transmitted to the MCU module so that the MCU module responds to the control parameters to control the diagnostic connector module to wake up the DoIP function of the vehicle under test. The diagnostic data is encoded into differential signal form through the Ethernet module and transmitted to the diagnostic interface of the vehicle under test through the Ethernet module. S102. When the vehicle under test sends DoIP data for diagnostic data, the MCU module controls the diagnostic connector module to transmit the DoIP data through the Ethernet module. The MCU module controls the Ethernet module to decode the received differential signal DoIP data into digital signal form, and forwards the digital signal DoIP data to the diagnostic device through the USB module.

[0025] In one possible implementation, the step of controlling the diagnostic connector module to wake up the DoIP function of the vehicle under test includes: Based on the control parameters, the diagnostic function of the vehicle under test is activated by the transistor switching circuit in the diagnostic connector module, so that the diagnostic connector module receives the DoIP data sent by the diagnostic interface of the vehicle under test, and transmits the DoIP data to the MCU module through the Ethernet module.

[0026] In one possible implementation, the method further includes: When sending diagnostic data to the vehicle under test, the digital signal received through the digital interface is encoded into an analog differential signal by the Ethernet physical layer chip, and the analog differential signal is converted into an analog differential network cable signal by the analog differential interface in the Ethernet module, so as to transmit the diagnostic data to the diagnostic interface of the vehicle under test through the Ethernet module. When the vehicle under test sends DoIP data for diagnostic data, the analog differential signal received through the analog differential interface is decoded into a digital signal by the Ethernet physical layer chip.

[0027] In one possible implementation, when the vehicle under test sends DoIP data for diagnostic data, the data format of the DoIP data is identified. The data format includes, but is not limited to, the data packet format of the data packet containing the DoIP data and the message format of the message containing the DoIP data. If the data format of the DoIP data is different from the preset format, the MCU module converts the data format of the DoIP data into the preset format. Then, the MCU module controls the diagnostic connector module to transmit the DoIP data through the Ethernet module. The MCU module controls the Ethernet module to decode the received differential signal DoIP data into digital signal format and forwards the digital signal DoIP data to the diagnostic device through the USB module.

[0028] Due to differences in vehicle models, factory settings, and other attribute information, implementing DoIP diagnostics via extended communication devices requires individual adaptation and debugging for each vehicle model, which is time-consuming and labor-intensive. Therefore, by identifying and converting the data format of the DoIP data, the system can automatically identify the DoIP data format reported by the vehicle under test for different models and factory settings. When the DoIP data format is inconsistent with the preset format, the MCU module can perform adaptive format conversion to uniformly adapt to the preset standard format. At the same time, relying on the MCU module to coordinate the control of the diagnostic connector module, Ethernet module, and USB module, the system can achieve bidirectional transmission of DoIP data and signal decoding and forwarding, effectively compatibility with the differences in DoIP data communication between different vehicle models and factory configurations. This eliminates the need for individual adaptation and debugging for each vehicle model, significantly improving the universality and compatibility of vehicle diagnostic interfacing, lowering the communication adaptation threshold between diagnostic equipment and the vehicle under test, and ensuring stable, compatible, and reliable diagnostic data transmission for various vehicles under test.

[0029] Specifically, for vehicles under test with different models and factory settings, the diagnostic DoIP data sent out has differentiated custom configurations in terms of data packet format, message frame structure, field arrangement, and protocol encapsulation rules. The system identifies the data format of the DoIP data uploaded by the vehicle under test. When it detects that the data packet format or message format of the DoIP data does not match the system's preset standard format, the MCU module performs data format parsing, frame structure reconstruction, field regularization, and protocol encapsulation conversion on the heterogeneous DoIP data. This converts the non-standard format (preset format) DoIP data into the preset format, eliminating the differences in DoIP data format caused by different vehicle models and factory configurations.

[0030] After the format conversion is completed, the MCU module controls the diagnostic connector module to complete the standardized DoIP data transmission via the Ethernet module. At the same time, it can decode the differential signal DoIP data received from the Ethernet into a digital signal and forward it to the diagnostic equipment via the USB module. This achieves unified compatibility of DoIP data formats for vehicles under test with multiple models and different factory versions, eliminating the need to develop separate adapter plugins and greatly improving the universality, adaptability, and data transmission reliability of vehicle diagnostic communication.

[0031] like Figure 2 As shown, the present invention provides an extended communication device for DoIP diagnostics, characterized in that the device includes: a USB module, an MCU module, an Ethernet module, and a diagnostic connector module; The USB module is used to receive diagnostic data and control parameters from the diagnostic device and transmit the diagnostic data and control parameters to the MCU module. The MCU module is used to respond to the control parameters to transmit the diagnostic data to the diagnostic interface of the vehicle under test via the Ethernet module and the diagnostic connector module. The diagnostic connector module is used to receive DoIP data sent by the diagnostic interface of the vehicle under test, and transmit the DoIP data to the MCU module through the Ethernet module; The MCU module is also used to forward the DoIP data to the diagnostic device via the USB module.

[0032] This invention enables diagnostic devices that previously did not support the DoIP protocol to perform diagnostics via DoIP. For automotive mechanics, this saves them the cost of purchasing new equipment. For diagnostic device manufacturers, it enhances the scalability of their devices and improves the product ecosystem. Furthermore, compared to traditional solutions that use three peripherals—USB to Ethernet, Ethernet cable, and diagnostic male to female connector—to extend the DoIP protocol, this invention integrates a USB module, an MCU module, an Ethernet module, and a diagnostic connector module. This results in a more compact and smaller device with simpler connections, making it more convenient for users and saving costs for manufacturers.

[0033] For example, the DoIP data received by the MCU has a specific data structure (defined in ISO13400). The length and check byte of the original data are then calculated, packaged, and sent to the diagnostic device via USB. Conversely, after the data from the diagnostic device is sent to the MCU via USB, the check byte is first calculated and compared with the check byte of the data packet to confirm that the data is complete. Then, the DoIP format original data packet is parsed through the format bytes such as the length of the data packet, and finally sent to the vehicle end through the Ethernet module.

[0034] For example, the DoIP data received by the MCU has a specific data structure (defined in ISO13400). The length and check byte of the original data are then calculated, packaged, and sent to the diagnostic device via USB. Conversely, after the data from the diagnostic device is sent to the MCU via USB, the check byte is first calculated and compared with the check byte of the data packet to confirm that the data is complete. Then, the DoIP format original data packet is parsed through the format bytes such as the length of the data packet, and finally sent to the vehicle end through the Ethernet module.

[0035] In one possible implementation, the MCU module includes: a main control chip, a filtering circuit, an RC reset circuit, a clock circuit, a flash memory chip, and an Ethernet interface. The filtering circuit filters the input current of the main control chip. The RC reset circuit is connected to the reset pin of the main control chip, enabling the main control chip to reset when the RC reset circuit provides a low level. The clock circuit provides a reference clock for the main control chip. The flash memory chip is connected to the main control chip via a storage interface circuit based on a flexible synchronous controller, allowing the main control chip to store data in the flash memory chip. An integrated MAC layer enables the main control chip to interact with the Ethernet module via the Ethernet interface.

[0036] For example, such as Figure 3 As shown, the main control chip uses the STM32F429IGT6 chip. The power supply circuit has multiple capacitor groups, namely O1~O3 groups (C61 / C62 / C63, C64 / C65 / C66, C67 / C68 / C69): each group is a classic combination of one large capacitor and two small capacitors. The large capacitor (10µF) filters low-frequency ripple and provides instantaneous current. The small capacitors (104 / 0.1µF) filter high-frequency noise, ensuring power purity. The capacitor group distribution principle is to place the capacitors as close as possible to the MCU's VDD (power) and VSS (ground) pins to form local power islands and reduce trace impedance. +1.2V core power supply (VDDA / VDD): - O4 group (C70 / C71 / C72): supplies power to the chip's internal core logic, requiring extremely high purity, and must be placed close to the pins. The reset circuit (R4, R2, C1) is connected as follows: +3.3V is connected to R4 (10KΩ), the RESET_N pin is connected, and capacitor C1 (10µF) is connected to GND. The reset circuit works as follows: Upon power-up, capacitor C1 acts as a short circuit, pulling the RESET_N pin low, and the MCU enters the reset state. As the capacitor charges, the voltage gradually increases, RESET_N becomes high, and the MCU ends the reset and starts up. R2 (1MΩ) is a pull-down resistor, which, together with C1, forms a simple RC reset circuit to ensure reliable reset. An external ETH_RST signal is also provided, supporting MCU reset via the Ethernet PHY or other peripherals.

[0037] The clock circuit (Y1, C2, C3) connection is as follows: OSC_IN / OSC_OUT → Y1 (8MHz) → C2 / C3 (20pF) → GND; Operating principle: The MCU's external high-speed crystal oscillator (HSE) provides an 8MHz reference clock. After the chip powers on, it defaults to using the internal RC clock (HSI), and then starts the external crystal oscillator. C2 / C3 are the load capacitors of the crystal oscillator, which determine the stability of the oscillation frequency; high-frequency capacitors of NP0 / C0G material must be selected.

[0038] Storage interface circuit (storage interface circuit based on flexible synchronous controller, FSMC): The MCU connects to an external parallel memory (flash memory chip) through the FSMC (flexible synchronous controller) to store large amounts of data such as diagnostic data, firmware, and images.

[0039] The main control chip pins are defined as follows: PD0~PD7FSMC_D0~D7 data bus (lower 8 bits); PD11 / PD12 / PD13FSMC_NOE / NWE / NE1 read / write / chip select control signals; PE7~PE15, PD14~PD15FSMC_D8~D15 data bus (higher 8 bits), totaling 16 bits of data width; PA1FLASH_CS external Flash chip select. Specifically, FLASH_SCK: connected to PD3, possibly the clock for the SPI interface (used for small Flash or debugging). FLASH_MOSI / MISO: PD10 / PD9, SPI communication lines. The FSMC interface typically connects to SDRAM or NAND Flash, greatly expanding the device's storage capacity for storing large diagnostic databases and UI resources.

[0040] Ethernet interface: The MCU integrates a MAC layer and connects to an external PHY chip through the RMII interface to achieve Ethernet communication (DoIP function).

[0041] ETH_MII_CRS_DV / ETH_MII_RXER: Receive relevant control signals.

[0042] ETH_MII_TXD0 / 1: Send data.

[0043] ETH_MII_TXEN: Send enabled.

[0044] ETH_MII_RXD0 / 1: Receive data.

[0045] ETH_MII_REF_CLK: Reference clock (provided by PHY).

[0046] During configuration and reset: R3 (10KΩ) + C3 (105 / 1µF): ​​This is the RC filter circuit for ETH_RST, used to provide a stable reset pulse to the PHY chip. PA0 / WKUP: Wake-up pin, which can be used for low-power wake-up and is also multiplexed with the ETH function.

[0047] Power supply regulation and filtering (L8, C70, C71): L8 (ferrite bead) + C70 / C71 (104): forms a π-type filter network. Specifically designed for high-frequency noise suppression of VDDA (analog power supply) or specific sensitive power supply pins. The ferrite bead blocks high-frequency noise, and the capacitor discharges residual noise to ground, ensuring that the accuracy of analog circuits (such as ADC, reference voltage) is not affected by digital switching noise.

[0048] The workflow is as follows: Power-on startup: The MCU power supply is stable, the reset circuit releases the reset, and the crystal oscillator starts oscillating to provide the clock. Boot loading: The chip reads the boot code from the internal Flash memory. System initialization: Configure peripherals such as the clock tree, GPIO, FSMC, and ETH. Function operation: Read external storage data through FSMC. Communicate with external devices through the ETH interface (DoIP diagnostics). Run the main application logic to control the overall operation of the device.

[0049] In one possible implementation, the USB module includes: a VBUS voltage divider detection circuit, a USB ESD protection circuit, and a Type-C interface circuit; wherein, the VBUS voltage divider detection circuit is used to power the diagnostic device, and the voltage divider node in the VBUS voltage divider detection circuit is connected to the ADC pin of the main control chip in the MCU module so that the MCU module can determine the operating status of the USB module; the VBUS voltage divider detection circuit is connected to the ESD protection chip in the USB ESD protection circuit, and the ESD protection chip is also connected to the USB differential signal; in the Type-C interface circuit, the power supply pin on the Type-C interface chip is connected in parallel with the VBUS voltage divider detection circuit to power the diagnostic device, the ground pin on the Type-C interface chip is connected in parallel with ground, and the differential data pin on the Type-C interface chip is used to receive diagnostic data and control parameters sent by the diagnostic device, and input the diagnostic data and control parameters into the ESD protection chip as a USB differential signal.

[0050] For example, such as Figure 4 As shown, the complete USB interface circuit includes three core modules: VBUS voltage divider detection, ESD protection, and Type-C interface, providing USB communication and power supply functions for the device.

[0051] The VBUS voltage divider detection circuit consists of: USB_VBUS → R39 (4.7KΩ) → voltage divider node → R40 (6.8KΩ) → GND.

[0052] The signal from the voltage divider node of the VBUS voltage divider detection circuit can be connected to the ADC pin of the MCU to detect the USB power supply voltage.

[0053] The VBUS voltage divider detection circuit is used to convert the 5V voltage from the USB into a low-voltage signal that can be detected by the MCU. The conversion formula is as follows: V_{\text{detection}} = V_{\text{USB_VBUS}} \times \frac{R40}{R39+R40}; Substituting the values: 5V \times \frac{6.8K}{4.7K+6.8K} ≈ 2.96V The MCU can determine whether the USB is plugged in and whether the power supply is normal by reading the voltage value, and can also calculate the actual VBUS voltage.

[0054] USB ESD protection circuit (D5 USBLO6-2SC6): USB differential signals USB_DP / USB_DM are connected to pins 1 and 3 of D5 respectively, VBUS is connected to pin 5, and GND is connected to pin 2.

[0055] The D5 is an integrated USB-specific ESD protection chip. Its core function is to protect the USB interface from electrostatic discharge (ESD) damage. It protects the USB DP, USB DM differential data lines, and VBUS power lines simultaneously. Its working mechanism is as follows: when the interface comes into contact with static electricity (such as during plugging or unplugging), the internal TVS diode will momentarily conduct, discharging the high voltage spike to ground and preventing high voltage from entering the downstream circuitry. Low capacitance: the chip has extremely low parasitic capacitance to USB signals, ensuring stable communication without affecting the high-speed transmission of USB differential signals.

[0056] The Type-C interface circuit (TYPE-C-16M) is a standard Type-C female connector interface with pins designed entirely according to the Type-C specification, enabling reversible USB communication and power supply.

[0057] Power and ground pin settings: VBUS: 4 pins (A4 / A9 / B9 / B4), all connected in parallel, used to transmit USB power supply voltage (5V). GND: 4 pins (A1 / A12 / B12 / B1), all connected in parallel, providing a grounding loop.

[0058] Differential data pin configuration: A7 (DN1) / A6 (DP1): Upper row of differential data lines, corresponding to USB D- and D+. B7 (DN2) / B6 (DP2): Lower row of differential data lines, corresponding to USB D- and D+. When the Type-C connector is plugged in either direction, one differential pair will be automatically connected to enable data communication.

[0059] CC configuration pins (CC1 / CC2) settings: A5 (CC1) and B5 (CC2): Key configuration pins for Type-C, their functions include: Reverse insertion detection: The device determines the insertion direction of the plug by detecting the connection status of the CC pins. Power supply negotiation: Through the voltage signal on the CC pins, the device can negotiate the power supply current with the power adapter to achieve fast charging or standard power supply. Mode configuration: It can also be used to configure the device's uplink / downlink role (master / slave).

[0060] SBU spare pins (SBU1 / SBU2): A8 (SBU1) and B8 (SBU2): Sideband Use signals, which are not typically used in Type-C 2.0, but are used to transmit auxiliary signals in high-speed modes such as USB 3.0 / DisplayPort.

[0061] The workflow is as follows: Device detection: When the USB cable is inserted into the Type-C interface, the MCU uses the CC pin and VBUS voltage divider circuit to identify whether the USB device is connected and whether the power supply is normal. Electrostatic discharge (ESD) protection: When plugging in, unplugging, or touching the device, the ESD chip D5 automatically discharges static electricity to protect the back-end circuitry. Data communication: After ESD protection, the USB differential signals DP / DM are transmitted to the back-end USB controller for data transmission and reception. Power supply transmission: VBUS is transmitted through the interface pins to power the device, and the MCU monitors the power supply status through the voltage divider circuit.

[0062] In one possible implementation, the Ethernet module includes an Ethernet physical layer chip, a power supply and reference circuit, a bias reference circuit, a crystal oscillator circuit, a reset circuit, and a digital interface. The power supply and reference circuit supplies power to the analog and digital circuits within the Ethernet physical layer chip. The bias reference circuit provides internal bias current to the Ethernet physical layer chip. The crystal oscillator circuit provides a reference clock to the Ethernet physical layer chip. The reset circuit resets the Ethernet physical layer chip. The Ethernet physical layer chip interacts with the MCU module via the digital interface.

[0063] For example, such as Figure 5As shown, the Ethernet physical layer chip uses a 100Mbps Ethernet physical layer (PHY) chip, which is used to convert digital RMII signals to analog differential network signals, allowing the MCU to send and receive data via the network cable.

[0064] The power supply and reference circuitry includes AVDD33 (analog power supply) and DVDD33 (digital power supply): supplying power to the internal analog and digital circuits of the chip, respectively, both at +3.3V. L1 (0805 600Ω@100MHz ferrite bead): isolates the digital and analog power supplies, preventing switching noise from the digital circuits from interfering with sensitive analog circuits. C7 / C8 / C9 / C10: multiple sets of decoupling capacitors filter out power supply ripple and ensure stable power supply.

[0065] Bias reference circuit (RBIAS pin 1): R5 (2.49KΩ 1% precision resistor): Provides the internal bias current reference for the chip, directly affecting the accuracy and stability of the Ethernet signal; a high-precision resistor must be used. C4 (104 capacitor): Filters out high-frequency noise from the bias circuit.

[0066] Crystal oscillator circuit (pins 30 / 31 XTAL_IN / OUT): Y2 (25MHz crystal oscillator) + R60 (1MΩ parallel resistor) + C72 / C73 (20pF load capacitor): Provides a 25MHz reference clock for the PHY chip, which is the "heartbeat" for Ethernet communication. R59 (390Ω resistor): Current limiting / matching resistor for the crystal oscillator to ensure stable oscillation.

[0067] Reset circuit (pin 21 RESET_N): R15 (4.7KΩ pull-up resistor) + R14 (100R current-limiting resistor) + C6 (104 capacitor): - When powered on, C6 charges to keep RESET_N at a low level, and the chip is reset; after charging is complete, RESET_N is pulled up to a high level, and the chip starts to work; the ETH_RST signal can also be actively pulled low by the MCU to achieve software reset.

[0068] The RMII digital interface is the digital communication interface between the PHY and the MCU. All signals are single-ended digital signals, defined as follows: 7 AVDD33 3.3V power supply; 8 RX_DV receive data valid signal; 9 / 10 RXD[1:0] receive data bits (connected to MCU's ETH_RMII_RXD0 / 1), series 33R resistor for impedance matching; 11 RXD2 / INT_N interrupt / additional signal, pull-up 4.7KΩ; 12 RXD3 / CLK_CTL clock control signal; 13 RXC RMII receive clock; 15 REF_CLK RMII reference clock, connected to MCU, series 33R resistor; 16 TXC RMII transmit clock; 17 / 18 TXD[1:0] transmit data bits (connected to MCU's ETH_RMII_TXD0 / 1); 19 TX_EN transmit enable signal (connected to MCU's ETH_RMII_TXEN); 27 RX_ER receive error signal, series 33R resistor; 26 The COL / CRS_DV collision detection / carrier listener signal uses a 33R resistor in series. All 33R resistors on the data lines are for matching the impedance of the RMII interface, reducing signal reflection, and ensuring the integrity of high-speed digital signals.

[0069] The Ethernet module also includes a management interface (SMI): MDC (pin 22): manages the data clock signal, output by the MCU, connected in series with a 33R resistor. MDIO (pin 23): manages the data input / output signal, connected to a 4.7KΩ pull-up resistor, used by the MCU to configure the operating mode of the PHY chip (speed, duplex, auto-negotiation, etc.).

[0070] The Ethernet module also includes a status indicator interface: LED1 / LED0 (pins 24 / 25): Ethernet status indicator control signal, usually connected to an LED, used to display link connection, data transmission and reception status, etc.

[0071] Optionally, the Ethernet module further includes an analog differential interface, which is used to convert the analog differential signal output by the Ethernet physical layer chip into an analog differential network cable signal, so as to transmit the diagnostic data to the diagnostic interface of the vehicle under test through the Ethernet module.

[0072] For example, such as Figure 5 As shown, the analog differential interface (communicating with the network cable / transformer) converts digital signals to analog differential network cable signals, and is connected to the external network cable through the H102NL network transformer.

[0073] Specifically, for the analog differential interface transmitter (TXN / TXP pins 3 / 4): R17 / R18 (10KΩ pull-down resistors): Default pull-down resistors to prevent signal floating interference. R19 / R20 (49.9Ω series resistors): Differential signal source matching resistors to match the network cable impedance. C11 / C12 (104 capacitors): DC blocking capacitors to block the DC component, allowing only the AC differential signal to pass through.

[0074] The analog differential interface transmits data to the network transformer H102NL. The functions of the network transformer H102NL are: 1. Signal isolation: Electrically isolates the equipment circuit from the external network cable to prevent high voltage from entering and damaging the equipment; 2. Impedance matching: Matches the differential signal at the PHY end to the 100Ω differential impedance of the network cable; 3. Differential-mode / common-mode filtering: Suppresses signal interference and improves anti-interference capability.

[0075] The network transformer H102NL transmits data to the receiving end (RX+ / RX- pins 10 / 16): R21 / R22 (75Ω resistors): Termination matching resistors on the secondary side of the transformer, matching the network cable impedance and reducing signal reflection. C15 (1000pF / 2KV capacitor): Common-mode filter capacitor for the network cable, filtering out common-mode interference and providing surge protection.

[0076] In one possible implementation, the Ethernet physical layer chip is used to encode digital signals received through a digital interface into analog differential signals, and the Ethernet physical layer chip is also used to decode analog differential signals received through an analog differential interface into digital signals.

[0077] The Ethernet module's workflow is as follows: Power-on initialization: Powered by a 3.3V power supply, the crystal oscillator provides a 25MHz clock, and after the reset circuit completes, the PHY chip enters the working state. MCU configuration: Through the SMI (MDC / MDIO) interface, the MCU configures the PHY's operating mode and enables auto-negotiation. Link establishment: The PHY sends differential signals through a transformer to negotiate the speed and duplex mode with the peer device, establishing an Ethernet link. Data transmission and reception: Transmission: The MCU sends digital data to the PHY through the RMII interface. The PHY encodes the data and converts it into differential signals, which are then transmitted to the network cable through the transformer. Reception: The differential signals from the network cable are isolated and filtered by the transformer, then decoded by the PHY into digital signals, which are transmitted to the MCU through the RMII interface. Status feedback: LED indicators display the link status, and the MCU can also read the PHY status register through the SMI to monitor communication quality.

[0078] In one possible implementation, the device further includes a power supply circuit for supplying power to the USB module, MCU module, Ethernet module, and diagnostic connector module, respectively. The power supply circuit includes an input circuit, a power supply expansion circuit, a first step-down circuit, a second step-down circuit, and a VBUS power supply circuit. The input circuit filters the vehicle power supply to obtain a stable voltage. The power supply expansion circuit decouples the stable voltage to provide a low-impedance power supply to the first step-down circuit. The first step-down circuit steps down the low-impedance power supply to obtain a 5V regulated power supply. The second step-down circuit steps down the 5V regulated power supply to obtain a 3.3V regulated power supply. The VBUS power supply circuit supplies power to the USB module.

[0079] For example, such as Figure 6 As shown, the multi-stage DC-DC power supply system (power supply circuit) designed for diagnostic equipment has the core function of converting the vehicle's 12V input into multiple stable voltages such as VDD, +3.3V, 5V, and VBUS required by the circuit. It also integrates reverse connection protection, filtering, voltage regulation, and USB power supply protection functions.

[0080] The input circuit path is: VIN → Fuse F1 → Zener diode D7 → Inductor L3 → VDD output; Key components: C17 / C18 / C19 / C74 (input filter capacitors), C20 / C75 (output filter capacitors).

[0081] The input circuit operates as follows: Overcurrent protection: F1 is a resettable fuse that blows when the input current is too high, protecting the downstream circuitry from damage. Surge / overvoltage protection: D7 is a TVS transient voltage suppressor diode that instantly breaks down and discharges when the vehicle power supply experiences a spike in high voltage, preventing damage to subsequent circuitry. LC filtering: L3 and C20 form a low-pass LC filter to remove high-frequency ripple and interference from the vehicle power supply, resulting in a clean VDD voltage (typically 12V). Capacitor filtering: Multiple capacitors (10µF / 104) in the front and rear stages respectively filter out low-frequency and high-frequency interference, ensuring a stable input power supply.

[0082] The path of the power supply expansion circuit is as follows: VDD nodes → Parallel connection of C21 / C22 / C23 / C24 / C25 and C28 / C29 / C30 / C31; Key component: Filter capacitor (10µF / 35V, 104).

[0083] The power supply extension circuit works as follows: the capacitor acts as a power supply decoupling / extension filter, providing a low-impedance power path for subsequent circuits. The large capacitor (10µF) filters out low-frequency ripple, while the small capacitor (104 / 0.1µF) filters out high-frequency noise, ensuring that the VDD voltage remains stable under load fluctuations and providing a clean input for the subsequent DC-DC converter.

[0084] The path of the first step-down circuit is: VDD input → U7 (SY8303AIC) step-down chip → L4 (10µH) → output UPV+, which is then regulated to 5V by diode D8. Key components: feedback resistor R48 (200K) / R50 (2.7K), frequency setting resistor R49 (21K), compensation capacitor C38 (100pF), filter capacitors C32 / C33 / C34 / C36.

[0085] The working principle of the first step-down circuit is as follows: SY8303AIC function: This is a synchronous step-down DC-DC chip that steps down the VDD (12V) voltage to a stable output voltage (UPV+). Output voltage calculation: The output voltage is set through the feedback resistor, and the formula is: V_{\text{OUT}} = 0.8 \times \left(1 + \frac{R48}{R50}\right) Substituting the value: 0.8 × (1 + 200K / 2.7K) ≈ 60V.

[0086] Inductors and capacitors: L4 is an energy storage inductor, and C32-C34 are output filter capacitors. Together they smooth the switching waveform and reduce ripple.

[0087] 5V generation: D8 is a Schottky diode, which prevents reverse current from flowing back into the 5V load and provides slight voltage drop compensation to ensure that the output is stable at 5V. C35 is the 5V output filter capacitor.

[0088] The path of the second step-down circuit is: 5V input → U6 (SY8077AAC) step-down chip → L5 (2.2µH) → output +3.3V.

[0089] Key components: Feedback resistor R53 (15K) / R54 (75K), compensation capacitor C48 (47pF), filter capacitors C39 / C40 / C41 / C43-C47 The working principle of the second step-down circuit is as follows: SY8077AAC function: synchronous step-down DC-DC chip, which converts 5V input to +3.3V output to power digital circuits such as MCU and sensors in the device.

[0090] Output voltage calculation: V_{\text{OUT}} = 0.6 \times \left(1 + \frac{R54}{R53}\right) Substituting the value: 0.6 × (1 + 75K / 15K) = 3.6V, which is close to 3.3V. It can be precisely set to 3.3V by fine-tuning the resistor.

[0091] EN pin control: The EN pin of U6 is controlled by the voltage divider R51 / R52. The default high level enables the chip to work; C42 is a soft-start capacitor to prevent the output voltage from overshooting when powered on.

[0092] Filtering circuit: L5 and multiple capacitors in the subsequent stage filter out switching ripple, ensuring stable +3.3V voltage and low noise, suitable for digital circuit use.

[0093] In one possible implementation, the VBUS power supply circuit includes a switching circuit composed of a transistor and a MOSFET, the switching circuit being used to control the output voltage of the VBUS power supply circuit.

[0094] For example, the VBUS power supply circuit path is: UPV+ → Q5 / Q4 (transistor) → Q6 (CJ3415 P-channel MOSFET) → Output VBUS.

[0095] The working principle of the VBUS power supply circuit is as follows: Control Logic: - When UPV+ is at a normal high level, Q5 is turned on, pulling the base of Q4 low, Q4 is turned off, the gate of Q6 is pulled up to the VBUS voltage by R57, VGS of Q6 = 0, the MOSFET is turned off, and there is no output. When VBUS needs to be turned on, the control signal pulls the base of Q5 low, Q5 is turned off, Q4 is turned on, pulling the gate voltage of Q6 low, VGS is negative, the P-channel MOSFET Q6 is turned on, and the UPV+ voltage is output to VBUS to power the USB device. Reverse Connection Protection: When VBUS is reverse-biased, the body diode of Q6 is reverse-biased, and the control circuit turns off the MOSFET to prevent reverse current from damaging the preceding circuit. Filtering Circuit: C49 / C51 / C50 filter out power supply ripple to ensure stable VBUS voltage.

[0096] In one possible implementation, the diagnostic connector module includes a diagnostic socket, an ESD four-channel protection array, a relay, and a transistor switching circuit. The diagnostic socket connects to the diagnostic interface of the vehicle under test (VAT) for data interaction. The ESD four-channel protection array protects the OBD bus within the diagnostic interface. The relay switches between CAN bus transmission and Ethernet signal transmission. The transistor switching circuit wakes up the diagnostic function of the VAT, enabling the diagnostic connector module to receive DoIP data sent by the VAT's diagnostic interface and transmit the DoIP data to the MCU module via the Ethernet module.

[0097] For example, such as Figure 7 As shown, the 15-pin diagnostic connector serves as the external physical interface, directly connecting to the vehicle's OBD bus. The circuit structure of the 15-pin diagnostic connector is as follows: Pin 1 (VIN): connected to the power input (usually the vehicle's 12V constant power); Pins 16 / 17 are ground. Pins 2-15: correspond to the 15 signal channels (OBD1-OBD15) defined in the OBD standard. After passing through series resistors (R26-R38), they output internal signals marked with ', such as OBD9' and OBD2'. The resistors serve two purposes: current limiting / matching, limiting bus current to protect downstream circuitry and matching bus impedance to reduce signal reflection interference.

[0098] The general-purpose ESD protection array (D1 / D2 / D3, model MMQA18VT1G) has a built-in bidirectional TVS diode in each channel, which is specifically designed to protect OBD bus signals from electrostatic discharge and surge voltage damage.

[0099] The working principle of a general-purpose ESD protection array: When a voltage spike exceeding 18V appears on the signal line, the TVS diode will instantly break down and conduct, discharging the high voltage to ground, thereby protecting the downstream circuitry. Coverage signals: D1 protects OBD1' / OBD2' / OBD9' / OBD10'; D2 protects OBD3' / OBD6' / OBD11' / OBD12'; D3 protects OBD7' / OBD8' / OBD13' / OBD14'.

[0100] Single-channel ESD protection (D4, model SZ1SMB18AT3G) Single-channel TVS diode, specifically designed to protect the OBD15' signal.

[0101] The U5 (relay G6J-2FS-Y DC12) enables switching between CAN bus and Ethernet signals. Its core is the SEL_DOIP control signal, which is used to switch between traditional CAN diagnostics and DoIP (Ethernet diagnostics).

[0102] Circuit principle of U5 (relay G6J-2FS-Y DC12): Pin 1 connects to a 5V power supply, and pin 8 connects to the SEL_DOIP signal via diode D6. When SEL_DOIP is high, the coil is energized, and the relay engages. Pins 3 and 4 connect to RX+ / OBD1' (CAN-H signal), corresponding to normally closed contacts, and connect to the OBD bus. Pins 6 and 5 connect to RX- / OBD9' (CAN-L signal), corresponding to normally closed contacts, and connect to the OBD bus. Pins 2 and 7 connect to OBD3' / OBD11', which are normally open contacts used for the signal path to switch to DoIP mode. Diode D6: This is the freewheeling diode for the coil, preventing the back electromotive force generated when the relay coil is de-energized from damaging the control circuit.

[0103] The transistor switching circuit includes: NPN transistor Q2, MOSFET Q3 (CJ3415, P-channel), and resistors R43 / R44 / R45 / R46 / R47. Based on the DOIP ACTIVE signal, it controls the OBD8' pin to output a 12V activation voltage, activating the vehicle's DoIP diagnostic function.

[0104] When DOIP ACTIVE is high, Q2 is turned on, pulling the gate of Q3 low. The P-channel MOSFET Q3 turns on when its gate voltage is lower than its source (VDD). VDD is output to OBD8' through Q3 and R47, sending a 12V activation signal to the vehicle. R46 is a pull-up resistor for Q3, ensuring that Q3 is off by default and OBD8' has no output.

[0105] NPN transistor Q1, resistors R41 / R42. Based on the RL_DOIP signal, output SEL_DOIP control signal to drive relay U5 to switch the signal path.

[0106] When RL_DOIP is high, Q1 is turned on, its collector is grounded, and a low-level SEL_DOIP signal is output. The relay does not operate, maintaining the traditional CAN mode. When RL_DOIP is low, Q1 is turned off, its collector is pulled up (powered by the relay coil), and a high-level SEL_DOIP signal is output. The relay is energized, switching to DoIP mode.

[0107] The workflow of the diagnostic connector module includes: when DOIP ACTIVE is low, Q2 / Q3 are off, and OBD8' has no 12V output. When RL_DOIP is high, Q1 is on; when SEL_DOIP is low, relay U5 remains normally closed; OBD1' / OBD9' are directly connected to RX+ / RX-; and the back-end circuit communicates with the vehicle via the CAN bus.

[0108] When DOIP ACTIVE is high, Q2 / Q3 are turned on, and OBD8' outputs a 12V activation signal to wake up the vehicle's DoIP function. When RL_DOIP is low, Q1 is turned off, and when SEL_DOIP is high, relay U5 is energized, connecting OBD3' / OBD11' to the backend Ethernet signal path, enabling Ethernet diagnostic communication.

[0109] All OBD signal channels are protected by current-limiting resistors and ESD protection arrays to effectively prevent damage to back-end equipment from electrostatic discharge, surges, and overvoltage.

[0110] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A DoIP diagnostic method, applied to an extended communication device for DoIP diagnostics, the device comprising a USB module, an MCU module, an Ethernet module, and a diagnostic connector module, characterized in that, The method includes: When sending diagnostic data to the vehicle under test, the diagnostic data and control parameters sent by the diagnostic device are received through the USB module, and the diagnostic data and control parameters are transmitted to the MCU module so that the MCU module responds to the control parameters to control the diagnostic connector module to wake up the DoIP function of the vehicle under test. The diagnostic data is encoded into differential signal form through the Ethernet module and transmitted to the diagnostic interface of the vehicle under test through the Ethernet module. When the vehicle under test sends DoIP data for diagnostic data, the MCU module controls the diagnostic connector module to transmit the DoIP data through the Ethernet module. The MCU module controls the Ethernet module to decode the received differential signal DoIP data into digital signal form, and forwards the digital signal DoIP data to the diagnostic device through the USB module.

2. The DoIP diagnostic method according to claim 1, characterized in that, The step of controlling the diagnostic connector module to wake up the DoIP function of the vehicle under test includes: Based on the control parameters, the diagnostic function of the vehicle under test is activated by the transistor switching circuit in the diagnostic connector module, so that the diagnostic connector module receives the DoIP data sent by the diagnostic interface of the vehicle under test, and transmits the DoIP data to the MCU module through the Ethernet module.

3. The DoIP diagnostic method according to claim 1, characterized in that, The method further includes: When sending diagnostic data to the vehicle under test, the digital signal received through the digital interface is encoded into an analog differential signal by the Ethernet physical layer chip, and the analog differential signal is converted into an analog differential network cable signal by the analog differential interface in the Ethernet module, so as to transmit the diagnostic data to the diagnostic interface of the vehicle under test through the Ethernet module. When the vehicle under test sends DoIP data for diagnostic data, the analog differential signal received through the analog differential interface is decoded into a digital signal by the Ethernet physical layer chip.

4. An extended communication device for DoIP diagnostics, characterized in that, The device includes: a USB module, an MCU module, an Ethernet module, and a diagnostic connector module; The USB module is used to receive diagnostic data and control parameters from the diagnostic device and transmit the diagnostic data and control parameters to the MCU module. The MCU module is used to respond to the control parameters to control the diagnostic connector module to wake up the DoIP function of the vehicle under test, and to encode the diagnostic data into differential signal form and transmit it to the diagnostic interface of the vehicle under test through the Ethernet module. The diagnostic connector module is used to receive DoIP data sent by the diagnostic interface of the vehicle under test, and transmit the DoIP data to the MCU module through the Ethernet module; The MCU module is also used to control the diagnostic connector module to transmit DoIP data through the Ethernet module. The MCU module decodes the received differential DoIP data into digital signal form and forwards the digital DoIP data to the diagnostic device through the USB module.

5. The extended communication device for DoIP diagnostics according to claim 4, characterized in that, The MCU module includes a main control chip, a filtering circuit, an RC reset circuit, a clock circuit, a flash memory chip, and an Ethernet interface. The filtering circuit filters the input current of the main control chip. The RC reset circuit is connected to the reset pin of the main control chip, enabling the main control chip to reset when the RC reset circuit provides a low level. The clock circuit provides a reference clock for the main control chip. The flash memory chip is connected to the main control chip via a storage interface circuit based on a flexible synchronous controller, allowing the main control chip to store data in the flash memory chip. An integrated MAC layer enables the main control chip to interact with the Ethernet module via the Ethernet interface.

6. The extended communication device for DoIP diagnostics according to claim 4, characterized in that, The USB module includes: a VBUS voltage divider detection circuit, a USB ESD protection circuit, and a Type-C interface circuit. The VBUS voltage divider detection circuit powers the diagnostic device, and its voltage divider node is connected to the ADC pin of the main control chip within the MCU module, enabling the MCU module to determine the operating status of the USB module. The VBUS voltage divider detection circuit is connected to the ESD protection chip in the USB ESD protection circuit, and the ESD protection chip is also connected to a USB differential signal. In the Type-C interface circuit, the power supply pin on the Type-C interface chip is connected in parallel with the VBUS voltage divider detection circuit to power the diagnostic device. The ground pin on the Type-C interface chip is connected in parallel to ground. The differential data pin on the Type-C interface chip receives diagnostic data and control parameters from the diagnostic device and inputs these data and parameters as a USB differential signal to the ESD protection chip. The ESD protection chip then transmits the diagnostic data and control parameters to the MCU module.

7. The extended communication device for DoIP diagnostics according to claim 4, characterized in that, The Ethernet module includes an Ethernet physical layer chip, a power supply and reference circuit, a bias reference circuit, a crystal oscillator circuit, a reset circuit, and a digital interface. The power supply and reference circuit supplies power to the analog and digital circuits within the Ethernet physical layer chip. The bias reference circuit provides internal bias current to the Ethernet physical layer chip. The crystal oscillator circuit provides a reference clock for the Ethernet physical layer chip. The reset circuit resets the Ethernet physical layer chip. The Ethernet physical layer chip interacts with the MCU module via the digital interface. The Ethernet module also includes an analog differential interface, which converts the analog differential signal output by the Ethernet physical layer chip into an analog differential network signal to transmit the diagnostic data to the diagnostic interface of the vehicle under test via the Ethernet module. The Ethernet physical layer chip encodes the digital signal received through the digital interface into an analog differential signal and decodes the analog differential signal received through the analog differential interface into a digital signal.

8. The extended communication device for DoIP diagnostics according to claim 4, characterized in that, The device further includes a power supply circuit for supplying power to the USB module, MCU module, Ethernet module, and diagnostic connector module. The power supply circuit includes an input circuit, a power supply expansion circuit, a first step-down circuit, a second step-down circuit, and a VBUS power supply circuit. The input circuit filters the vehicle power supply to obtain a stable voltage. The power supply expansion circuit decouples the stable voltage to provide a low-impedance power supply to the first step-down circuit. The first step-down circuit steps down the low-impedance power supply to obtain a 5V regulated power supply. The second step-down circuit steps down the 5V regulated power supply to obtain a 3.3V regulated power supply. The VBUS power supply circuit supplies power to the USB module.

9. The extended communication device for DoIP diagnostics according to claim 8, characterized in that, The VBUS power supply circuit includes a switching circuit composed of transistors and MOSFETs, which is used to control the output voltage of the VBUS power supply circuit.

10. The extended communication device for DoIP diagnostics according to claim 4, characterized in that, The diagnostic connector module includes a diagnostic socket, an ESD four-channel protection array, a relay, and a transistor switching circuit. The diagnostic socket connects to the diagnostic interface of the vehicle under test (VAT) for data exchange. The ESD four-channel protection array protects the OBD bus within the diagnostic interface. The relay switches between CAN bus transmission and Ethernet signal transmission. The transistor switching circuit wakes up the diagnostic function of the VAT, enabling the diagnostic connector module to receive DoIP data sent by the VAT's diagnostic interface and transmit the DoIP data to the MCU module via the Ethernet module.

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