A CAN and LIN signal acquisition circuit

Abstract

The utility model provides a kind of CAN and LIN signal acquisition circuit, including single-chip microcontroller U1, CAN communication circuit, LIN communication circuit;The single-chip microcontroller U1 is used for power management, CAN / LIN signal analysis, with display screen module circuit carries out data transmission, data is sent to SD card module circuit and is stored;The CAN communication circuit is used for collecting the data of CAN signal acquisition table pen and with single-chip microcontroller U1 communication, the LIN communication circuit is used for collecting the data of LIN signal acquisition table pen and with single-chip microcontroller U1 communication.The utility model solves the problem that the operation of existing CAN / LIN monitoring analysis equipment is not convenient enough, and the cost is higher.

Description

Technical Field

[0001] This utility model relates to the field of signal detection technology, and in particular to a CAN and LIN signal acquisition circuit. Background Technology

[0002] Currently, most car manufacturers use CAN / LIN signals for data transmission in key switches to reduce costs and achieve fault detection. However, detecting these signals requires external communication equipment connected to a computer via USB to monitor and analyze the data, and then operating a host computer interface to view and store the data, or using an oscilloscope for monitoring and analysis. However, these devices are expensive, heavy, and bulky, making them inconvenient to use. Furthermore, both computers and oscilloscopes require an external 220V power supply to operate, making them unusable or unsuitable for prolonged use in certain environments. Therefore, there is a need to invent a CAN and LIN signal acquisition circuit. Utility Model Content

[0003] The purpose of this invention is to provide a CAN and LIN signal acquisition circuit to solve the problems of inconvenient operation and high cost of existing CAN / LIN monitoring and analysis equipment.

[0004] The technical solution adopted by this utility model to solve its technical problem is:

[0005] A CAN and LIN signal acquisition circuit includes a microcontroller U1, a CAN communication circuit, and a LIN communication circuit;

[0006] The CAN communication circuit includes a CAN transceiver U3. The data transmitting end of the CAN transceiver U3 is connected to the CAN data receiving end of the microcontroller U1, and the data receiving end of the CAN transceiver U3 is connected to the CAN data transmitting end of the microcontroller U1. The enable end of the CAN transceiver U3 is connected to the CAN enable end of the microcontroller U1. The CAN_H end of the CAN transceiver U3 is connected to the first end of the CAN data acquisition unit, and the CAN_L end of the CAN transceiver U3 is connected to the second end of the CAN data acquisition unit.

[0007] The LIN communication circuit includes a LIN transceiver U4, the enable terminal of which is connected to the second terminal of a second resistor R2, and the first terminal of the second resistor R2 is connected to the LIN enable terminal of a microcontroller U1.

[0008] The LIN signal terminal of the LIN transceiver U4 is connected to the first terminal of the tenth capacitor C10, the first terminal of the third bidirectional TVS tube TVS3, and the LIN signal detection terminal, respectively. The LIN signal detection terminal is connected to the first terminal of the LIN acquisition device. The second terminal of the tenth capacitor C10 is grounded, and the second terminal of the third bidirectional TVS tube TVS3 and the second terminal of the LIN acquisition device are both grounded. The LIN detection ground terminal connected to the LIN transceiver U4 is grounded.

[0009] The LIN data transmitting end of the LIN transceiver U4 is connected to the LIN data receiving end of the microcontroller U1, and the LIN data receiving end of the LIN transceiver U4 is sequentially connected to the LIN data transmitting end of the microcontroller U1.

[0010] Preferably, in conjunction with the above scheme, the circuit further includes a power supply circuit, which includes an LDO regulator U2, a first resistor R1, a first diode D1, a first TVS diode TVS1, and a second TVS diode TVS2. The input terminal VIN of the LDO regulator U2 is connected to the negative terminal of the first diode D1, and the positive terminal of the first diode D1 is connected to the second terminal of the first resistor R1 and the first terminal of the first bidirectional TVS diode TVS1. The first terminal of the first resistor R1 is connected to the power supply BAT, and the second terminal of the first bidirectional TVS diode TVS1 is grounded. The output terminal VDD of the LDO regulator U2 is connected to the first terminal of the second bidirectional TVS diode TVS2, and the second terminal of the second bidirectional TVS diode TVS2 is grounded. A high-voltage power supply output terminal is led out from the input terminal VIN of the LDO regulator U2, and a low-voltage power supply output terminal is led out from the output terminal VDD of the LDO regulator U2.

[0011] Preferably, in conjunction with the above scheme, the power supply circuit further includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9. The first terminal of the first capacitor C1, the first terminal of the second capacitor C2, the first terminal of the third capacitor C3, the first terminal of the fourth capacitor C4, the first terminal of the fifth capacitor C5, and the first terminal of the sixth capacitor C6 are all connected to the second terminal of the first diode D1. The second terminals of the first capacitor C1, the second terminal of the second capacitor C2, the second terminal of the third capacitor C3, and the second terminal of the fourth capacitor C4 are grounded. The first terminals of the seventh capacitor C7, the first terminals of the eighth capacitor C8, and the first terminals of the ninth capacitor C9 are all connected to the output terminal VDD of the LDO regulator U2. The second terminals of the fifth capacitor C5, the second terminals of the sixth capacitor C6, the second terminals of the capacitor C7, the second terminals of the eighth capacitor C8, and the second terminals of the ninth capacitor C9 are connected together.

[0012] Preferably, in conjunction with the above scheme, the high-voltage power supply output terminal of the power supply circuit is connected to the VBAT power supply terminal of the LIN transceiver U4 in the LIN communication circuit. The VBAT power supply terminal line of the LIN transceiver U4 is connected to the first terminal of the eleventh capacitor C11 and the first terminal of the twelfth capacitor C12, respectively. The second terminal of the eleventh capacitor C11 and the second terminal of the twelfth capacitor C12 are grounded together.

[0013] Preferably, in conjunction with the above scheme, the high-voltage power supply output terminal of the power supply circuit is connected to the positive terminal of the second diode D2 in the LIN communication circuit, the negative terminal of the second diode D2 is connected to the first terminal of the third resistor R3, and the second terminal of the third resistor R3 is connected to the LIN signal terminal of the LIN transceiver U4.

[0014] Preferably, in conjunction with the above scheme, the VCC power output terminal of the LIN transceiver U4 is connected to the second terminal of the fourteenth capacitor C14, the second terminal of the thirteenth capacitor C13, and the VCC power input terminal of the microcontroller U1, respectively, and the first terminal of the fourteenth capacitor C14 and the first terminal of the thirteenth capacitor C13 are grounded together.

[0015] Preferably, in conjunction with the above scheme, the low-voltage power supply output terminal and the high-voltage power supply output terminal of the power supply circuit supply power to the low-voltage power supply terminal and the high-voltage power supply terminal of the CAN transceiver U3 in the CAN communication circuit, respectively.

[0016] Preferably, in conjunction with the above scheme, the circuit further includes an SD card module circuit, wherein the SD card module circuit includes a chip select signal terminal CS, a clock signal terminal SCK, a master output / slave input terminal MOSI, a master input / slave output terminal MISO, a power supply terminal VCC, and a ground terminal GND connected to the microcontroller U1.

[0017] Preferably, in conjunction with the above scheme, the circuit further includes a display module circuit, which includes a display connector P2 connected to the microcontroller U1. The four sets of power backlight cathode input terminals on the display connector P2 are respectively connected to the second terminals of the eighth resistor, the ninth resistor, the tenth resistor, and the eleventh resistor. The first terminals of the eighth resistor, the ninth resistor, the tenth resistor, and the eleventh resistor are interconnected and then connected to the collector of the first transistor Q1. The emitter of the first transistor Q1 is grounded, and the base of the first transistor Q1 is connected to the display backlight control terminal of the microcontroller U1.

[0018] The beneficial effects of this utility model are as follows: The CAN and LIN signal acquisition circuit of this utility model can be carried out in a small circuit board and device. It is not limited to monitoring the CAN / LIN communication of the whole vehicle. It can monitor and display any CAN / LIN communication product, realizing the universality of CAN / LIN signal acquisition. It is convenient for operators to read and store data in real time, and the energy consumption is very low, which is conducive to long-term monitoring and analysis of some fault data. Furthermore, the acquisition device made using this utility model is easy to carry, simple to operate, and has a low production cost.

[0019] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is the circuit diagram of the microcontroller in this utility model.

[0021] Figure 2 This is a CAN communication circuit diagram of this utility model.

[0022] Figure 3 This is a LIN communication circuit diagram of this utility model.

[0023] Figure 4 This is the power supply circuit diagram of this utility model.

[0024] Figure 5 This is a circuit diagram of the SD card module in this utility model.

[0025] Figure 6 This is a circuit diagram of the display module in this utility model.

[0026] Figure 7 This is a block diagram of the CAN / LIN signal acquisition system in this utility model. Detailed Implementation

[0027] like Figures 1 to 3 The circuit shown is a CAN and LIN signal acquisition circuit, characterized in that it includes a microcontroller U1, a CAN communication circuit, and a LIN communication circuit.

[0028] The CAN communication circuit includes a CAN transceiver U3, and the data transmitting end of the CAN transceiver U3 (i.e. Figure 3 Pin 1 (TXD, corresponding to CAN_TX) is connected to the CAN data receiver of microcontroller U1 (i.e., Figure 1 Pin 89, PC6 (corresponding to CAN_TX), is the data receiving terminal of the CAN transceiver U3 (i.e., Figure 3 Pin 4 (RXD, corresponding to CAN_RX) is connected to the CAN data transmitter of microcontroller U1 (i.e., Figure 1Pin 88, PC5 (corresponding to CAN_RX), is the enable pin of the CAN transceiver U3 (i.e., Figure 3 Pin 6 (EN, corresponding to CANFDEN) is connected to the CAN enable pin of microcontroller U1 (i.e., ...). Figure 1 Pin G11 of the CAN transceiver U3 (corresponding to CANFDEN); the CAN_H terminal of the CAN transceiver U3 is connected to the first terminal of the CAN acquisition device, CAN_H_TO_CON (red CAN signal acquisition probe), and the CAN_L terminal of the CAN transceiver U3 is connected to the second terminal of the CAN acquisition device, CAN_L_TO_CON (black CAN signal acquisition probe).

[0029] The LIN communication circuit includes a LIN transceiver U4. The enable terminal of the LIN transceiver U4 is connected to the second terminal of the second resistor R2 (current limiting resistor), and the first terminal of the second resistor R2 is connected to the LIN enable terminal of the microcontroller U1 (i.e., Figure 1 Pin 22, PD14, corresponds to LINEN;

[0030] The LIN signal terminal of the LIN transceiver U4 is connected to the first terminal of the tenth capacitor C10, the first terminal of the third bidirectional TVS transistor TVS3, and the LIN signal detection terminal LIN_TO_CON. The LIN signal detection terminal LIN_TO_CON is connected to the first terminal of the LIN acquisition device (red LIN signal acquisition probe). The second terminal of the tenth capacitor C10 is grounded. The second terminal of the third bidirectional TVS transistor TVS3 is grounded together with the second terminal of the LIN acquisition device LIN_TO_GND (connected to the black LIN grounding probe). The third bidirectional TVS transistor serves as an anti-static device.

[0031] The LIN transceiver U4's LIN data sending end (i.e. Figure 4 Pin 6 (TXD, corresponding to LIN_TX) is connected to the LIN data receiver LIN_TX pin of microcontroller U1 (i.e., Figure 1 Pin 24 (PH6, corresponding to LIN_TX) of the LIN transceiver U4 (i.e., the LIN data receiver). Figure 4 Pin 5 (RXD, corresponding to LIN_RX) is connected to the LIN data transmitter LIN_RX pin of microcontroller U1 (i.e., Figure 1 Pin 25, PH14, corresponds to LIN_RX.

[0032] like Figure 4As shown, in order to power the CAN communication circuit and LIN communication circuit and convert the 12V voltage to 5V, the circuit also includes a power supply circuit. The power supply circuit includes an LDO regulator U2 (i.e., an LDO low-dropout linear regulator), a first resistor R1, a first diode D1, a first TVS diode TVS1, and a second TVS diode TVS2. The input terminal VIN of the LDO regulator U2 is connected to the cathode of the first diode D1, and the anode of the first diode D1 is connected to the second terminal of the first resistor R1 and the first bidirectional TVS diode TVS1. At one end, the first end of the first resistor R1 is connected to the power supply BAT (powered by a lithium battery or an external 9-16V power supply), and the second end of the first bidirectional TVS diode TVS1 is grounded; the output terminal VDD of the LDO regulator U2 is connected to the first end of the second bidirectional TVS diode TVS2, and the second end of the second bidirectional TVS diode TVS2 is grounded; a VCC_12V high-voltage power supply output terminal is led out from the input terminal VIN of the LDO regulator U2, and a VCC_5V low-voltage power supply output terminal is led out from the output terminal VDD of the LDO regulator U2. Both the first TVS diode TVS1 and the second TVS diode TVS2 serve to prevent static electricity and surge.

[0033] To achieve energy storage and filtering effects and make the power supply more stable, the power supply circuit also includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9. The first terminal of the first capacitor C1, the first terminal of the second capacitor C2, the first terminal of the third capacitor C3, the first terminal of the fourth capacitor C4, the first terminal of the fifth capacitor C5, and the first terminal of the sixth capacitor C6 are all connected to the second terminal of the first diode D1. The second terminals of the first capacitor C1, the second terminal of the second capacitor C2, the second terminal of the third capacitor C3, and the second terminal of the fourth capacitor C4 are grounded. The first terminals of the seventh capacitor C7, the first terminals of the eighth capacitor C8, and the first terminals of the ninth capacitor C9 are all connected to the output terminal VDD of the LDO regulator U2. The second terminals of the fifth capacitor C5, the second terminals of the sixth capacitor C6, the second terminals of the capacitor C7, the second terminals of the eighth capacitor C8, and the second terminals of the ninth capacitor C9 are connected together.

[0034] In order to supply power to the LIN communication circuit, the power supply output terminal VCC_12V of the power supply circuit is connected to the VBAT power supply terminal of the LIN transceiver U4 in the LIN communication circuit; in order to ensure stable power supply, the VBAT power supply terminal line of the LIN transceiver U4 is connected to the first terminal of the eleventh capacitor C11 and the first terminal of the twelfth capacitor C12 respectively, and the second terminal of the eleventh capacitor C11 and the second terminal of the twelfth capacitor C12 are grounded together.

[0035] To meet the requirements of the LIN master node, the VCC_12V power supply output terminal of the power supply circuit is connected to the positive terminal of the second diode D2 in the LIN communication circuit. The negative terminal of the second diode D2 is connected to the first terminal of the third resistor R3 (current limiting resistor). The second terminal of the third resistor R3 is connected to the LIN signal terminal of the LIN transceiver U4.

[0036] To power the microcontroller U1, the VCC power output terminal of the LIN transceiver U4 is connected to the second terminal of the fourteenth capacitor C14, the second terminal of the thirteenth capacitor C13, and the VCC power input terminal of the microcontroller U1 (i.e., Figure 1 The first terminal of the fourteenth capacitor C14 and the first terminal of the thirteenth capacitor C13 are grounded together (pins 10, 61, and 87).

[0037] In order to power the CAN communication circuit, the VCC_5V low-voltage power supply output terminal and the VCC_12V high-voltage power supply output terminal of the power supply circuit respectively supply power to the VCC_5V low-voltage power supply terminal of the CAN transceiver U3 in the CAN communication circuit (i.e., Figure 2 Pin 3 (VCC), pin 5 (VIO), and the VCC_12V high-voltage power supply terminal (i.e. Figure 2 Pin 10 (VBAT) in the middle.

[0038] In order to store the detection data transmitted from the microcontroller U1, such as Figure 5 As shown, the SD card module circuit includes a chip select signal terminal CS, a clock signal terminal SCK, a master output / slave input terminal MOSI, a master input / slave output terminal MISO, a power supply terminal VCC, and a ground terminal GND, all connected to the microcontroller U1. The SD card module can support cards up to 32GB in size and theoretically can store up to 6 billion CAN messages, enabling real-time storage of CAN / LIN detection data.

[0039] In order to display the CAN / LIN detection data transmitted from the microcontroller U1 on the TFT display screen, such as Figure 6 As shown, the display module circuit includes a display connector P2 connected to the microcontroller U1. The four sets of power backlight cathode input terminals on the display connector P2 are respectively connected to the second terminals of the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11. The first terminals of the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, and the eleventh resistor R11 are interconnected and then connected to the collector of the first transistor Q1. The emitter of the first transistor Q1 is grounded, and the base of the first transistor Q1 is connected to the display backlight control terminal of the microcontroller U1 (i.e.,...). Figure 1Pin 33, PE10, corresponds to BL_CTR. Resistors R8 (eighth), R9 (ninth), R10 (tenth), and R11 (eleventh) are all current-limiting resistors.

[0040] The CAN and LIN signal acquisition circuits of this invention can be used to construct a CAN / LIN signal acquisition device, such as... Figure 7 As shown, the components of this data collector are:

[0041] 1. Main Control Module: Includes microcontroller U1, CAN communication circuit, LIN communication circuit, and power supply circuit. The main control board can perform power management, CAN / LIN signal parsing, transmit data with the display module circuit via SPI communication, and send data to the SD card module circuit for storage via SPI.

[0042] 2. Display module: Connects to the display module circuit, supports SPI communication, and displays the CAN / LIN detection data transmitted from the main control board.

[0043] 3. SD Card Module: Connects to the SD card module circuit, supports SPI communication, and stores the CAN / LIN detection data transmitted from the main control board.

[0044] 4. External CAN / LIN signal acquisition probes: Used to receive external CAN / LIN input signals and play a signal transmission role.

[0045] Detailed operation procedure for CAN / LIN signal acquisition device:

[0046] Select the appropriate CAN or LIN detection channel based on the communication method of the sample being tested. For CAN communication, insert the red CAN signal probe into the CAN_H channel and the black CAN signal probe into the CAN_L channel. For LIN communication, insert the red LAN signal probe into the LIN channel and the black LIN ground probe into the GND ground channel. After the CAN / LIN signal acquisition unit is powered on, it automatically configures parameters according to the selected detection channel, selects the appropriate baud rate and ID for the current state, performs real-time data parsing and conversion, and sends the data to the display module and SD card module via SPI communication. The display module displays the data in real time, and the SD card module stores the data in real time.

[0047] In this invention, the display module can be an HSD 2.8-inch display provided by Shenzhen Yongda Electronics Co., Ltd. The microcontroller U1 can be a KF32F156MQV model from Shanghai Chipwin Microelectronics Technology Co., Ltd.; the CAN transceiver U2 can be an NXP TJA1043 model; and the LIN transceiver U4 can be an NXP TJA1028 model.

[0048] In the description of this utility model, it should be understood that terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model patent, unless otherwise stated, "a plurality of" means two or more.

[0049] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0050] The present invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or any direct application to other situations without modification, fall within the protection scope of the present invention.

Claims

1. A CAN and LIN signal acquisition circuit, characterized in that, Includes microcontroller U1, CAN communication circuit, and LIN communication circuit; The CAN communication circuit includes a CAN transceiver U3. The data transmitting end of the CAN transceiver U3 is connected to the CAN data receiving end of the microcontroller U1, and the data receiving end of the CAN transceiver U3 is connected to the CAN data transmitting end of the microcontroller U1. The enable end of the CAN transceiver U3 is connected to the CAN enable end of the microcontroller U1. The CAN_H end of the CAN transceiver U3 is connected to the first end of the CAN data acquisition unit, and the CAN_L end of the CAN transceiver U3 is connected to the second end of the CAN data acquisition unit. The LIN communication circuit includes a LIN transceiver U4, the enable terminal of which is connected to the second terminal of a second resistor R2, and the first terminal of the second resistor R2 is connected to the LIN enable terminal of a microcontroller U1. The LIN signal terminal of the LIN transceiver U4 is connected to the first terminal of the tenth capacitor C10, the first terminal of the third bidirectional TVS tube TVS3, and the LIN signal detection terminal, respectively. The LIN signal detection terminal is connected to the first terminal of the LIN acquisition device. The second terminal of the tenth capacitor C10 is grounded, and the second terminal of the third bidirectional TVS tube TVS3 is grounded together with the second terminal of the LIN acquisition device. The LIN detection ground terminal connected to the LIN transceiver U4 is grounded. The LIN data transmitting end of the LIN transceiver U4 is connected to the LIN data receiving end of the microcontroller U1, and the LIN data receiving end of the LIN transceiver U4 is sequentially connected to the LIN data transmitting end of the microcontroller U1.

2. The CAN and LIN signal acquisition circuit according to claim 1, characterized in that, The circuit also includes a power supply circuit, which comprises an LDO regulator U2, a first resistor R1, a first diode D1, a first TVS diode TVS1, and a second TVS diode TVS2. The input terminal VIN of the LDO regulator U2 is connected to the negative terminal of the first diode D1. The positive terminal of the first diode D1 is connected to the second terminal of the first resistor R1 and the first terminal of the first bidirectional TVS diode TVS1. The first terminal of the first resistor R1 is connected to the power supply BAT, and the second terminal of the first bidirectional TVS diode TVS1 is grounded. The output terminal VDD of the LDO regulator U2 is connected to the first terminal of the second bidirectional TVS diode TVS2, and the second terminal of the second bidirectional TVS diode TVS2 is grounded. A high-voltage power supply output terminal is led out from the input terminal VIN of the LDO regulator U2, and a low-voltage power supply output terminal is led out from the output terminal VDD of the LDO regulator U2.

3. The CAN and LIN signal acquisition circuit according to claim 2, characterized in that, The power supply circuit further includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9. The first terminal of the first capacitor C1, the first terminal of the second capacitor C2, the first terminal of the third capacitor C3, the first terminal of the fourth capacitor C4, the first terminal of the fifth capacitor C5, and the first terminal of the sixth capacitor C6 are all connected to the second terminal of the first diode D1. The second terminals of the first capacitor C1, the second terminal of the second capacitor C2, the second terminal of the third capacitor C3, and the second terminal of the fourth capacitor C4 are grounded. The first terminals of the seventh capacitor C7, the first terminals of the eighth capacitor C8, and the first terminals of the ninth capacitor C9 are all connected to the output terminal VDD of the LDO regulator U2. The second terminals of the fifth capacitor C5, the second terminals of the sixth capacitor C6, the second terminals of the capacitor C7, the second terminals of the eighth capacitor C8, and the second terminals of the ninth capacitor C9 are connected together.

4. The CAN and LIN signal acquisition circuit according to claim 2, characterized in that, The high-voltage power supply output terminal of the power supply circuit is connected to the VBAT power supply terminal of the LIN transceiver U4 in the LIN communication circuit. The VBAT power supply terminal line of the LIN transceiver U4 is connected to the first terminal of the eleventh capacitor C11 and the first terminal of the twelfth capacitor C12 respectively. The second terminal of the eleventh capacitor C11 and the second terminal of the twelfth capacitor C12 are grounded together.

5. The CAN and LIN signal acquisition circuit according to claim 2, characterized in that, The high-voltage power supply output terminal of the power supply circuit is connected to the positive terminal of the second diode D2 in the LIN communication circuit. The negative terminal of the second diode D2 is connected to the first terminal of the third resistor R3. The second terminal of the third resistor R3 is connected to the LIN signal terminal of the LIN transceiver U4.

6. The CAN and LIN signal acquisition circuit according to claim 1, characterized in that, The VCC power output terminal of the LIN transceiver U4 is connected to the second terminal of the fourteenth capacitor C14, the second terminal of the thirteenth capacitor C13, and the VCC power input terminal of the microcontroller U1, respectively. The first terminal of the fourteenth capacitor C14 and the first terminal of the thirteenth capacitor C13 are grounded together.

7. The CAN and LIN signal acquisition circuit according to claim 2, characterized in that, The low-voltage power supply output terminal and the high-voltage power supply output terminal of the power supply circuit supply power to the low-voltage power supply terminal and the high-voltage power supply terminal of the CAN transceiver U3 in the CAN communication circuit, respectively.

8. The CAN and LIN signal acquisition circuit according to claim 1, characterized in that, The circuit also includes an SD card module circuit, which includes a chip select signal terminal CS, a clock signal terminal SCK, a master output / slave input terminal MOSI, a master input / slave output terminal MISO, a power supply terminal VCC, and a ground terminal GND connected to the microcontroller U1.

9. The CAN and LIN signal acquisition circuit according to claim 1, characterized in that, The circuit also includes a display module circuit, which includes a display connector P2 connected to the microcontroller U1. The four sets of power backlight cathode input terminals on the display connector P2 are respectively connected to the second terminals of the eighth, ninth, tenth, and eleventh resistors. The first terminals of the eighth, ninth, tenth, and eleventh resistors are interconnected and then connected to the collector of the first transistor Q1. The emitter of the first transistor Q1 is grounded, and the base of the first transistor Q1 is connected to the display backlight control terminal of the microcontroller U1.

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