GPIO (General Purpose Input / Output) cross-board anti-interference circuit and automobile lamp intelligent control device
By employing a GPIO cross-board anti-interference circuit in the automotive lighting control system, and utilizing signal buffers and ferrite beads to enhance signal driving force and isolate the circuit, the EMC interference problem in cross-board signal transmission is solved, thereby achieving reliability and stability of the lighting control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JHETECH
- Filing Date
- 2025-06-21
- Publication Date
- 2026-04-17
AI Technical Summary
In the prior art, automotive lighting control systems are susceptible to EMC interference during cross-board signal transmission, which can lead to uncontrollable signal changes or lighting malfunctions. Furthermore, existing anti-interference circuit designs are complex and unreliable.
The GPIO cross-board anti-interference circuit is adopted. By setting signal buffers and ferrite beads on the main control and execution PCB boards, the signal driving force is enhanced and the circuit is isolated. The fixed high and low level of the signal buffer and the floating output design are used to avoid the floating state. Combined with Schmitt trigger input and enable pin control, stable signal transmission is achieved.
It improves the anti-interference capability of cross-board signal transmission, ensures the reliability and stability of vehicle lighting functions, avoids vehicle lighting function failure due to signal interference, and meets EMC test requirements.
Smart Images
Figure CN224137645U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of automotive control circuits, specifically to a GPIO cross-board anti-interference circuit and an intelligent control device for automotive lights. Background Technology
[0002] With the increasing electrification and intelligence of vehicles, the control of automotive lights is becoming increasingly intelligent and complex. For highly complex automotive lights and control systems, a single PCB board cannot implement all the functions of the entire system. Functional boards, driver boards, and lamp boards all need to be designed separately to ensure convenient design, clear functional structure, and ease of installation and testing. This differentiated PCB design does not affect EMC immunity testing of high-current power lines. However, for low-current signal lines, especially ordinary I / O ports, I2C communication lines, SPI communication lines, and UART interface lines used for signal control of automotive lights, EMC performance will be tested during cross-board signal transmission. During high-current injection BCI experiments for EMC, signal transmission may be interfered with. Slight interference may cause uncontrollable brightness changes in the controlled lamps, while severe interference may cause the lamps to go out and not recover. Currently, the commonly used anti-interference circuit design uses a control method that converts signals before transmission, resulting in a complex circuit structure that cannot guarantee transmission reliability. The main goal of engineers is to design convenient anti-interference circuits for cross-board signal connections so that they can pass EMC testing. Summary of the Invention
[0003] The purpose of this application is to overcome the shortcomings of the prior art and provide a GPIO cross-board anti-interference circuit and an intelligent control device for automotive lights, which can improve the anti-interference of cross-board transmission of vehicle control signals and improve circuit reliability.
[0004] Firstly, this application provides a GPIO cross-board anti-interference circuit, including a main control PCB board and an execution PCB board, which adopts the following technical solution:
[0005] The main control PCB board is equipped with a control chip MCU and a signal buffer U1. The VCC pin of the signal buffer U1 is connected to the input voltage. The signal buffer U1 includes several main control buffer channels. Each main control buffer channel is equipped with an input pin and an output pin. Each input pin is connected to each signal output terminal of the control chip MCU. Each output pin is connected to a signal impedance matching resistor and a ferrite bead in sequence, and then connected to the connector output interface of the main control PCB board.
[0006] The execution PCB board is equipped with a signal buffer U2 and an execution chip LEDdriver. The VCC pin of the signal buffer U2 is connected to the input voltage. The signal buffer U2 includes several execution buffer channels, which correspond one-to-one with the main control buffer channels. Each execution buffer channel is equipped with one input pin and one output pin. Each input pin is connected to a signal impedance matching resistor and a ferrite bead in sequence, and then connected to the connector input interface of the execution PCB board. Each output pin is connected to the input terminal of the execution chip LEDdriver, and the execution chip LEDdriver is connected to an LED. The connector output interface of the main control PCB board and the connector input interface of the execution PCB board are connected through an intermediate wiring harness.
[0007] By adopting the above technical solution, the main control PCB board and the execution PCB board are not directly connected across boards. Before the MCU control chip on the main control PCB board outputs a signal, the signal is first amplified by the signal buffer U1 to increase the signal drive current. Then, the signal passes through the signal impedance matching resistors and anti-interference ferrite beads set on the main control PCB board and the execution PCB board respectively, and the corresponding channel of the anti-interference input signal buffer U2. The signal is then converted by the signal buffer U2 into a control signal adapted to the execution chip LEDdriver, thereby controlling the execution chip LEDdriver. The above system can amplify the signal through the signal buffer, enhance the signal drive force, and isolate the circuits of the main control PCB board and the execution PCB board, thus improving the anti-interference effect of signal transmission across boards.
[0008] Preferably, for the main control buffer channel, the input pin of one main control buffer channel is grounded, the corresponding output pin is left floating, and all other input pins are connected to the output terminal of the control chip MCU respectively. The main control buffer channel in use is connected to the control signal, and the main control buffer channel not in use is connected to the high level or low level signal.
[0009] For execution buffer channels, the input pin of one execution buffer channel is grounded, the corresponding output pin is left floating, and all other input pins are connected one by one to the output pin of the main control buffer channel to obtain control signals, or high-level or low-level signals. The output pin of the execution buffer channel in use is connected to the input terminal of the execution chip LEDdriver, and the output pin of the execution buffer channel not in use is left floating.
[0010] By adopting the above technical solution, the input pins of the signal buffer are fixed to a high or low level, which can prevent unconnected input pins from being in a floating state and prevent the pin level from being affected by environmental electromagnetic interference or coupling with external noise, causing the input level to oscillate near the logic threshold. The output pins of unsuitable channels of the signal buffer are left floating, which is equivalent to an open circuit, which can isolate possible bus conflicts and simplify circuit design.
[0011] Preferably, the master control buffer channel of the signal buffer U1 and the execution buffer channel of the signal buffer U2 adopt Schmitt trigger input.
[0012] The above technical solution ensures that the channel output state remains unchanged when the input signal fluctuates in the signal hysteresis region from VT- to VT+, reducing noise interference to signal transmission and repairing signal fluctuations or upper edge degradation caused by long-distance transmission.
[0013] Preferably, the enable pins OE1 and OE2 of the signal buffers U1 and U2 are both grounded.
[0014] Preferably, the enable pin OE1 or enable pin OE2 of the signal buffer U1 is connected to the level conversion circuit, or the enable pin OE1 or enable pin OE2 of the signal buffer U2 is connected to the level conversion circuit.
[0015] The above technical solutions provide different operational implementation methods for signal buffers. Both enable pins OE1 and OE2 are grounded and at a low level, causing the signal buffer to be automatically enabled and operational by default. Alternatively, if enable pin OE1 or OE2 is connected to a level shifting circuit, it can control the signal buffer's on / off state through level switching. When either enable pin OE1 or OE2 receives a high level, either signal buffer is disabled, resulting in a high impedance output from the output pin and interrupting signal transmission in the system.
[0016] Preferably, the input voltage of the signal buffer U1 and the signal buffer U2 is 3.3V.
[0017] The above scheme ensures that the corresponding VT+ range is 0.8 to 2.2V, the VT- range is 0.5 to 1.2V, and the hysteresis voltage ΔVT range is 0.3 to 1.2V. The final output drive current for inter-board signal transmission is approximately 12mA, which is within an appropriate range and can meet the requirements for anti-interference signal transmission. It also avoids problems such as EMI radiation, circuit overheating, and impedance mismatch caused by excessive current.
[0018] Secondly, the intelligent control device for automotive lights provided in this application adopts the aforementioned GPIO cross-board anti-interference circuit.
[0019] In summary, this application includes at least one of the following beneficial technical effects:
[0020] 1. This application provides an anti-interference circuit for cross-board signal transmission, which can improve the circuit's anti-interference capability. It is especially suitable for cross-board transmission of low-current signal lines such as automotive headlight control signals, improving the reliability of low-current signal lines and enabling the circuit to pass EMC testing.
[0021] 2. The vehicle headlight intelligent control device using the anti-interference circuit of this application can avoid problems such as headlight malfunction, flickering, and brightness changes caused by signal interference as much as possible. The circuit function operates reliably and stably, improving product quality and user satisfaction. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of a GPIO cross-board anti-interference circuit in an embodiment of this application;
[0023] Figure 2 This is a schematic diagram of another GPIO cross-board anti-interference circuit in an embodiment of this application. Detailed Implementation
[0024] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of this application.
[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that in the optional embodiments of this application, the object information and other related data involved require the permission or consent of the object when the embodiments of this application are applied to specific products or technologies, and the collection, use, and processing of related data must comply with the relevant laws, regulations, and standards of the relevant countries and regions. That is to say, if the embodiments of this application involve data related to the object, it needs to be obtained with the authorization and consent of the object, the authorization and consent of the relevant departments, and in compliance with the relevant laws, regulations, and standards of the country and region. If personal information is involved in the embodiments, the acquisition of all personal information requires the consent of the individual. If sensitive information is involved, the separate consent of the information subject is required, and the embodiments also need to be implemented with the authorization and consent of the object.
[0026] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.
[0027] Example 1:
[0028] Please see Figure 1 This application discloses a GPIO cross-board anti-interference circuit, which includes a main control PCB board 1 and an execution PCB board 2.
[0029] The main control PCB board 1 houses the control chip MCU and the signal buffer U1. The VCC pin of the signal buffer U1 is connected to the input voltage, and the GND pin is grounded. Filter capacitors C1 and C2 are connected across the two lines. The function of the signal buffer U1 is to amplify the control signals from the MCU, improving the signal driving capability and preventing interference signals from interfering with high-current signal lines.
[0030] The signal buffer U1 includes several main control buffer channels. Each buffer channel has one input pin and one output pin. Each input pin is connected to a signal output terminal of the control chip MCU, and each output pin is connected to a signal impedance matching resistor and an anti-interference element ferrite bead, and then connected to the connector output interface of the main control PCB board. In this embodiment, the signal buffer U1 has a total of 8 main control buffer channels. The input pins are A1, A2, A3, A4, A5, A6, A7, and A8, the output pins are Y1, Y2, Y3, Y4, Y5, Y6, Y7, and Y8, the signal impedance matching resistors are R1, R3, R5, R7, R9, R11, and R13, and the ferrite beads are B1, B3, B5, B7, B9, B11, and B13.
[0031] It should be noted that for the main control buffer channel, input pin A8 is grounded, output pin Y8 is floating, and the remaining input pins A1 to A7 are all connected to the output terminals of the control chip MCU. This prevents the input pins from being in a floating state and avoids the pin levels being affected by environmental electromagnetic interference or coupling with external noise. The main control buffer channel in use is connected to the control signal of the control chip MCU, while unused main control buffer channels are connected to high or low level signals through the control chip MCU. On the same main control buffer channel, the output pin corresponding to the input pin outputs the signal, which is then output to the external board through a signal impedance matching resistor and a ferrite bead via the connector output interface of the main control PCB board.
[0032] The execution PCB board 2 contains a signal buffer U2 and an execution chip LEDdriver. The circuit of signal buffer U2 is basically the same as that of signal buffer U1. The VCC pin is connected to the input voltage, the GND pin is grounded, and filter capacitors C3 and C4 are connected between the two lines. Signal buffer U2 is used to receive amplified signals and convert them into control signals that match the execution chip LEDdriver.
[0033] In this embodiment, the signal buffer U2 includes eight execution buffer channels, each corresponding one-to-one with the main control buffer channel. The input pins of the execution buffer channels are A1, A2, A3, A4, A5, A6, A7, and A8, and the output pins are Y1, Y2, Y3, Y4, Y5, Y6, Y7, and Y8. The signal impedance matching resistors are R2, R4, R6, R8, R10, R12, and R14, and the ferrite beads are B2, B4, B6, B8, B10, B12, and B14. The execution chip LEDdriver is connected to LEDs D1, D2, and D3 to control them.
[0034] Similarly, for the execution buffer channel, input pin A8 is grounded, and output pin Y8 is left floating. The remaining input pins A1 to A7 of the execution buffer channel are connected sequentially to a signal impedance matching resistor and a ferrite bead, and then connected one-to-one to the connector input interface of the execution PCB board. The connector output interface of the main control PCB board 1 and the connector input interface of the execution PCB board 2 are connected via intermediate wiring harness 3, which distinguishes the buffer channels. In this embodiment, the length of intermediate wiring harness 3 is 60cm. For the execution buffer channel, the output pins of the used execution buffer channel are connected to the input terminal of the execution chip LEDdriver, while the output pins of the unused execution buffer channel are left floating. In this embodiment, output pins Y3, Y4, and Y7 of the execution buffer channel are connected to the input terminal of the execution chip LEDdriver, and the remaining output pins are left floating.
[0035] The following explanation uses the three buffer channels used in this embodiment as an example to further illustrate signal transmission.
[0036] 1. The MCU, the control chip on the main control PCB board 1, sends a PWM signal through its PWM pin. This signal enters the input pin A3 of the signal buffer U1, then is output from the output pin Y3. After passing through the impedance matching resistor R5 and the ferrite bead B5, it reaches the connector output interface. Through the intermediate wiring harness 3, it is transmitted to the ferrite bead B6 and impedance matching resistor R6 on the execution PCB board 2, and then to the input pin A3 of the signal buffer U2. From the output pin Y3, it is output to the PWM pin of the execution chip LEDdriver, performing PWM dimming on LEDs D1-D3. The dimming frequency can reach 137kHz, and the flicker is imperceptible to both the camera and the naked eye.
[0037] 2. The MCU control chip in the main control PCB board 1 sends high and low level signals through the GPIO pins, which enter the input pin A4 of the signal buffer U1 and are output from the output pin Y4. The signals reach the input pin A4 of the signal buffer U2 in the execution PCB board 2 and are output from the output pin Y4. This controls the switching of the LEDdriver pin of the execution chip, ensuring that the LED is turned off without delay when the system is reset. A high level enables the LED driver, and a low level enables the LED driver to turn off.
[0038] 3. The MCU control chip in the main control PCB board 1 sends high and low level signals through GPIO pins, which enter the input pin A7 of the signal buffer U1 and are output from the output pin Y7. These signals then reach the input pin A7 of the signal buffer U2 on the execution PCB board 2 and are output from the output pin Y7, controlling the EN2 pin of the LEDdriver chip. This ensures that LEDs D1-D3 are turned off without delay upon system reset; a high level turns off LEDs D1-D3, and a low level turns them on. These two control methods achieve dual EN control, ensuring reliable LED shutdown.
[0039] It should be noted that the eight buffer channels in this embodiment are a redundant backup design, and the signal buffer actually only uses three channels. If the product has multiple LED driving requirements, the redundant backup design can be used directly for channel connection without redesigning the circuit. Furthermore, those skilled in the art will understand that the naming of the main control PCB board 1 and the execution PCB board 2 in this embodiment is a functional naming method and does not constitute a limitation on the PCB board connection method. Cross-board signal connections between PCB boards with other functions or that are not in a main control-execution relationship will not exceed the scope of this application embodiment when using the anti-interference circuit.
[0040] Example 2:
[0041] Based on Example 1, signal buffers U1 and U2 are eight-channel independent logic buffers with tri-state outputs and Schmitt trigger inputs. Signal buffers U1 and U2 each include enable pins OE1 and OE2. When both enable pins OE1 and OE2 are simultaneously low, the signal buffers are enabled to output, and the input pins output either a high or low level signal corresponding to the input pin. Conversely, when either enable pin OE1 or OE2 is high, the signal buffer outputs are disabled, and the output pins output high impedance. The specific functional modes of the signal buffers are shown in the table below.
[0042]
[0043] For inputs, L represents a low level, H represents a high level, and X is not considered.
[0044] For the output, L represents low level, H represents high level, X is negligible, and Z represents high impedance.
[0045] Please see Figure 1In one embodiment, the enable pins OE1 and OE2 of signal buffers U1 and U2 are both grounded, meaning that once connected to the telecommunications network, the signal buffers are enabled by default for interference-resistant signal transmission. This is also the standard wiring method for interference-resistant circuits.
[0046] Please see Figure 2 In another embodiment, the enable pin OE1 of the signal buffer U1 is connected to a level conversion circuit, which can switch between high and low levels to control the on / off state of the interference-resistant circuit. This wiring method is suitable for circuits requiring EMC testing, and can control the on / off state of the circuit according to the start and stop commands of the test.
[0047] The following describes the testing of the embodiments of this application through BCI testing.
[0048] The requirements for radio frequency current injection immunity are as follows:
[0049] Classified by functional importance, vehicle lighting control belongs to Category C. Category C is defined as: functions that play a decisive role in the operation and control of the vehicle, and whose failure may affect the safety of vehicle driving or pedestrians on the road.
[0050] According to the functional execution status classification, the car manufacturer requires functional level status I, which is specifically explained as follows: the test part can perform all its pre-designed functions during and after the application of interference, and the tolerances caused by the interference are all within the design error range of the test part.
[0051] The specific experimental method for BCI testing is as follows:
[0052] The test method for RI02 is performed in accordance with ISO 11452-4 and meets the following requirements:
[0053] a) The test uses the "substitution method" and is conducted in an electromagnetic shielding room or a semi-anechoic chamber;
[0054] b) If the product performance can reach state I under the test level conditions, then the next level of testing need not be performed;
[0055] c) The distance between the DUT and the load cell / artificial power network is 1700mm (+300 / -0mm);
[0056] d) The test setup should distinguish between two injection modes: differential large current injection (DBCI) and common-mode large current injection (CBCI);
[0057] e) 0.1MHz~30MHz, using DBCI setup, the current injection probe should be placed at 150mm and 450mm from the DUT connector for testing respectively; the DUT power return line should be placed outside the high current injection probe, and other DUT wiring harnesses should be placed inside the probe.
[0058] f) For 30MHz to 400MHz, using CBCI layout, the current injection probe should be placed at a distance of 450mm and 750mm from the DUT connector for testing; all DUT wiring harnesses should be placed inside the high current injection probe.
[0059] g) If the DUT has multiple connectors, each individual connector harness needs to be tested at 0.1MHz to 400MHz as described above.
[0060] h) If the DUT cannot meet the test requirements, the injected current value should be gradually reduced until the DUT works normally, and then the injected current value should be gradually increased until the DUT shows abnormality. The frequency and current value at this time should be recorded in the test report as the deviation threshold.
[0061] Based on the above BCI test method, the DBCI and CBCI tests of the GPIO cross-board anti-interference circuit of this application were performed. The LEDs showed no abnormalities. The test was conducted at the test level and met the functional level I required by the car manufacturer.
[0062] In another embodiment, this application provides an intelligent control device for automotive lights, which employs the aforementioned GPIO cross-board anti-interference circuit.
[0063] Unless otherwise stated, pins not explicitly described in the circuit diagrams of this application (such as power supply pin VCC, ground pin GND, enable pin EN, etc.) are connected in accordance with the conventional methods used by those skilled in the art, and such connections do not constitute a limitation on the technical solution of this invention. Passive components such as decoupling capacitors and pull-up / pull-down resistors not shown in the figures are connected in accordance with general specifications for electronic circuit design (such as IEEE standards), and specific parameters can be adjusted according to the actual application scenario.
[0064] Those skilled in the art will understand that Figure 1 and Figure 2 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the electronic device to which the present application is applied. The specific electronic device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.
[0065] As used in the above embodiments, depending on the context, the term "when..." can be interpreted as meaning "if...", "after...", "in response to determining...", or "in response to detecting...". Similarly, depending on the context, the phrase "when determining..." or "if (the stated condition or event) is interpreted as meaning "if determining...", "in response to determining...", "when (the stated condition or event) is detected", or "in response to detecting (the stated condition or event)".
[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A GPIO cross-board anti-interference circuit, comprising a main control PCB board and an execution PCB board, characterized in that: The main control PCB board is equipped with a control chip MCU and a signal buffer U1. The VCC pin of the signal buffer U1 is connected to the input voltage. The signal buffer U1 includes several main control buffer channels. Each main control buffer channel is equipped with an input pin and an output pin. Each input pin is connected to each signal output terminal of the control chip MCU. Each output pin is connected to a signal impedance matching resistor and a ferrite bead in sequence, and then connected to the connector output interface of the main control PCB board. The execution PCB board is equipped with a signal buffer U2 and an execution chip LEDdriver. The VCC pin of the signal buffer U2 is connected to the input voltage. The signal buffer U2 includes several execution buffer channels, which correspond one-to-one with the main control buffer channels. Each execution buffer channel is equipped with an input pin and an output pin. Each input pin is connected to a signal impedance matching resistor and a ferrite bead in sequence, and then connected to the connector input interface of the execution PCB board. Each output pin is connected to the input terminal of the execution chip LEDdriver, and the execution chip LEDdriver is connected to the LED light. The connector output interface of the main control PCB board and the connector input interface of the execution PCB board are connected through an intermediate wiring harness.
2. The GPIO cross-board anti-interference circuit according to claim 1, characterized in that, For the main control buffer channel, the input pin of one main control buffer channel is grounded, the corresponding output pin is left floating, and all other input pins are connected to the output terminal of the control chip MCU respectively. The main control buffer channel in use is connected to the control signal, and the main control buffer channel not in use is connected to the high level or low level signal. For execution buffer channels, the input pin of one execution buffer channel is grounded, the corresponding output pin is left floating, and all other input pins are connected one by one to the output pin of the main control buffer channel to obtain control signals, or high-level or low-level signals. The output pin of the execution buffer channel in use is connected to the input terminal of the execution chip LEDdriver, and the output pin of the execution buffer channel not in use is left floating.
3. The GPIO cross-board anti-interference circuit according to claim 1, characterized in that, The main control buffer channel of the signal buffer U1 and the execution buffer channel of the signal buffer U2 adopt Schmitt trigger input.
4. The GPIO anti-jamming circuit across boards according to claim 3, wherein, The enable pins OE1 and OE2 of both signal buffers U1 and U2 are grounded.
5. The GPIO anti-jamming circuit across boards according to claim 3, wherein, The enable pin OE1 or enable pin OE2 of the signal buffer U1 is connected to the level conversion circuit, or the enable pin OE1 or enable pin OE2 of the signal buffer U2 is connected to the level conversion circuit.
6. The GPIO anti-jamming circuit across boards of claim 1, wherein, The input voltage of the signal buffer U1 and the signal buffer U2 is 3.3V.
7. An intelligent control device for an automotive vehicle lamp, characterized by The GPIO cross-board anti-interference circuit described in any one of claims 1 to 6 is adopted.