Anti-interference intelligent cabinet control device

Abstract

The utility model relates to intelligent cabinet technical field especially relates to a kind of anti-interference intelligent cabinet control device, including PCB substrate, and main control connection circuit, power management circuit, audio processing circuit, HDMI display interface circuit, network communication circuit and peripheral expansion circuit being set on PCB substrate;Main control connection circuit is configured as connection RK3288 core board;Power management circuit connects external DC power supply, and after conversion, respectively for core board and each peripheral circuit power supply;The signal end of HDMI display interface circuit, audio processing circuit and network communication circuit is respectively connected to main control connection circuit;Peripheral expansion circuit includes USB hub circuit, and USB hub circuit is connected to main control connection circuit by differential signal line, and the scheme effectively improves the anti-interference ability and anti-static performance of device, guarantees the transmission quality of audio and video signal.

Description

Technical Field

[0001] This utility model relates to the field of intelligent cabinet technology, and in particular to an anti-interference intelligent cabinet control device. Background Technology

[0002] With the popularization of Internet of Things (IoT) technology, smart parcel lockers, self-service lockers, and other smart terminal devices have been widely used in public places. These devices are typically driven by a core control board, which is responsible for handling tasks such as human-computer interaction, network communication, and peripheral control.

[0003] However, because smart cabinets are typically installed in complex electromagnetic environments such as high-traffic areas or outdoors, and users frequently touch the display screen, buttons, or plug and unplug peripheral interfaces during use, they are highly susceptible to electrostatic discharge (ESD) or electromagnetic interference (EMI). Existing smart cabinet control motherboards often lack robust interface protection and anti-interference circuit designs; for example, effective filtering and ESD protection devices are not installed at audio output, network interface, or button signal terminals. This leads to problems such as damage to the main control chip due to ESD breakdown during long-term operation, or communication interruptions and high audio noise levels due to common-mode noise interference, severely affecting the stability and lifespan of the smart cabinet. Utility Model Content

[0004] In order to solve the technical problems of the lack of a sound protection design for the control motherboard in the prior art, which leads to poor stability of the equipment in complex environments and susceptibility to electrostatic damage, this utility model proposes an anti-interference intelligent cabinet control device.

[0005] This utility model is achieved through the following technical solution: An anti-interference intelligent cabinet control device includes a PCB substrate, and a main control connection circuit, a power management circuit, an audio processing circuit, an HDMI display interface circuit, a network communication circuit, and a peripheral expansion circuit disposed on the PCB substrate. The main control connection circuit is configured to connect to an RK3288 core board. The power management circuit is connected to an external DC power supply, which, after conversion, supplies power to the core board and each peripheral circuit. The signal terminals of the HDMI display interface circuit, the audio processing circuit, and the network communication circuit are respectively connected to the main control connection circuit. The peripheral expansion circuit includes a USB hub circuit, which is connected to the main control connection circuit via differential signal lines.

[0006] Furthermore, the HDMI display interface circuit includes an HDMI interface socket J13; the four pairs of differential signal pins of the HDMI interface socket are all connected to the main control connection circuit, a pull-up resistor is connected between the hot-plug detection pin of the HDMI interface socket and the power supply terminal, a filter capacitor C98 is connected in parallel next to the power supply pin of the HDMI interface socket, and the ground terminal is connected to the PCB ground plane.

[0007] Furthermore, the audio processing circuit includes power amplifier chips U101 and U102 and a speaker interface socket J10. The input terminal of the power amplifier chip is connected to the audio output pin of the main control connection circuit through a coupling capacitor. The output terminal of the power amplifier chip is connected to an LC filter circuit. The LC filter circuit includes inductors L4 and L12 connected in series and capacitors C126 and C127 connected in parallel to ground. The output terminal of the LC filter circuit is connected to the speaker interface socket.

[0008] Furthermore, the audio processing circuit also includes a microphone interface circuit, which includes a microphone socket J41. ESD protection diodes ED35 and ED36 are connected in parallel on the signal line of the microphone socket to prevent external static electricity from damaging the internal circuit.

[0009] Furthermore, the network communication circuit includes an RJ45 network transformer interface socket J12; the RJ45 network transformer interface socket is connected to four sets of differential signal lines, each set of differential signal lines is connected in series with a common-mode inductor to suppress common-mode noise interference, and the RJ45 network transformer interface socket integrates a network connection indicator and a data transmission indicator.

[0010] Furthermore, the power management circuit includes DC-DC buck converter chips U2 and U3; the input terminal of the DC-DC buck converter chip is connected to a 12V DC power supply, and a transient suppression diode ED1 is connected in parallel at the input terminal; the output terminal of the DC-DC buck converter chip is connected to power inductors L1 and L2 and a filter capacitor bank, for outputting a stable 5V voltage and system voltage.

[0011] Furthermore, the USB hub circuit includes a USB HUB controller chip U9. The upstream port of the USB HUB controller chip is connected to the main control connection circuit, and the downstream port of the USB HUB controller chip is connected to multiple USB interface sockets. Each data line of the USB interface socket is equipped with a low-capacitance ESD protection device.

[0012] Furthermore, the PCB substrate is also provided with a debugging and status indication circuit, which includes a debugging serial port header J17 and multiple sets of LED indicators; the signal lines of the debugging serial port header are connected in series with resistors and grounded through ESD diodes ED29 and ED30 respectively, and the multiple sets of LED indicators include power indicator, working status indicator and custom indicator, which are connected to the GPIO pins of the main control connection circuit through MOSFET or transistor driving circuits respectively.

[0013] Furthermore, a button control circuit is also provided on the PCB substrate; the button control circuit includes a reset button KEY2, a power button KEY3 and a restore button KEY1, and the signal terminals of each button are connected in parallel with ESD electrostatic protection diodes ED26, ED27 and ED28, and are connected with pull-up resistors. Beneficial effects

[0014] (1) This utility model sets a transient suppression diode at the power input end to prevent surge voltage impact, connects a common mode inductor in series in the network interface circuit to suppress common mode noise, and configures ESD electrostatic protection diodes at all external interaction interfaces such as microphone, USB, debugging interface and buttons. This effectively solves the problem of main control chip crashing or being damaged due to human electrostatic discharge or electromagnetic interference in outdoor or densely populated environments, and greatly improves the reliability of the system. (2) The present invention designs an LC filter circuit at the output end of the audio power amplifier, which effectively filters out high-frequency noise and current noise in the audio signal, ensuring the clarity of the voice broadcast; at the same time, a filter capacitor is connected in parallel next to the power pin of the HDMI display interface and the grounding design is strengthened to ensure the stability of the high-definition video signal transmission and avoid screen flickering or screen distortion. (3) The present invention sets a pull-up resistor on the hot-plug detection pin of the HDMI interface and uses a low capacitance ESD protection device on the USB data line, so that when users or maintenance personnel plug and unplug external display devices or USB peripherals in a powered state, they can effectively discharge static charge and stabilize the level signal, and prevent instantaneous current surge from damaging the internal interface circuit. In summary, this solution effectively improves the device's anti-interference capability and anti-static performance by setting up comprehensive filtering and electrostatic protection circuits at the power supply, network, and various peripheral interfaces, ensuring the transmission quality of audio and video signals. At the same time, in conjunction with the modular design of the RK3288 core board and onboard status indicator lights, it significantly reduces the operation and maintenance costs and troubleshooting difficulty of the intelligent cabinet. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the main control connection circuit of an anti-interference intelligent cabinet control device proposed in this utility model; Figure 2 This utility model presents a schematic diagram of the power management circuit for an anti-interference intelligent cabinet control device. Figure 3 This utility model presents a schematic diagram of a USB hub circuit for an anti-interference intelligent cabinet control device. Figure 4 This invention provides a schematic diagram of the HDMI display interface circuit for an anti-interference intelligent cabinet control device. Figure 5 This is a schematic diagram of the network communication circuit of an anti-interference intelligent cabinet control device proposed in this utility model; Figure 6 This utility model presents a schematic diagram of the button control circuit for an anti-interference intelligent cabinet control device. Figure 7 This utility model presents a schematic diagram of the debugging and status indication circuit for an anti-interference intelligent cabinet control device. Figure 8 This is a schematic diagram of the audio processing circuit of an anti-interference intelligent cabinet control device proposed in this utility model; Figure 9 This invention relates to a schematic diagram of the microphone interface circuit for an anti-interference intelligent cabinet control device. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model. Example

[0018] refer to Figure 1This embodiment provides an anti-interference intelligent cabinet control device. The device uses a PCB substrate as its hardware carrier and integrates a main control connection circuit, a power management circuit, an audio processing circuit, an HDMI display interface circuit, a network communication circuit, and a peripheral expansion circuit. The core processor of the main control connection circuit uses an RK3288 chip. The RK3288 processor serves as the system's control center and is connected to a storage unit, a clock unit, and various peripheral interfaces via an internal bus. In terms of storage configuration, the RK3288 is connected to two sets of 2128M 16bit DDR3 memory chips, forming a 32-bit wide high-speed memory, and is also connected to an eMMC chip for storing system firmware. In terms of clock configuration, the processor is connected to a 24MHz main crystal oscillator and a 32.768kHz RTC clock circuit to maintain accurate operation of system logic and timing.

[0019] The power management circuit is responsible for supplying energy to the entire system. After the external 12V DC power supply is connected via the interface, it first passes through a transient suppression diode ED1 connected in parallel at the input terminal to absorb any surge voltage that the external power supply may carry. The core power conversion uses DC-DC step-down converter chips U2 and U3 to convert the 12V input voltage to the 5V system voltage required by the RK3288 core board and various peripherals. To ensure the purity of the output voltage, the output terminals of the DC-DC chips are connected to power inductors L1 and L2, as well as a filter capacitor bank composed of multiple capacitors, effectively reducing ripple interference and ensuring system stability under high loads.

[0020] In terms of network communication, the device adopts a combined wired and wireless architecture. The RK3288 connects to the PHY chip via a GMAC interface and ultimately to the RJ45 network transformer interface socket J12. To adapt to complex industrial environments, the J12 integrates a network transformer, and all four differential signal lines connected to the J12 are connected in series with common-mode inductors for bidirectional suppression of common-mode noise interference. The J12 also integrates network connection indicator lights and data transmission indicator lights. Simultaneously, the RK3288 connects to an AP6210 WiFi / BT dual-function module via an SDIO interface, providing wireless communication capabilities.

[0021] For multimedia interaction, video output is achieved through the HDMI interface of the RK3288, connected to HDMI connector J13. The four pairs of differential signal pins of J13 are directly connected to the main control circuit. To prevent damage from hot-plugging, a pull-up resistor is connected between the hot-plug detection pin of the HDMI connector and the power supply terminal, and a filter capacitor C98 is connected in parallel next to the power supply pin. The ground terminal is tightly connected to the PCB ground plane. The audio processing circuit consists of two parts: output and input. The audio output signal, after being sent by the main control, enters the power amplifier chips U101 and U102. The power amplifier output is connected to an LC filter circuit composed of inductors L4 and L12 and capacitors C126 and C127, filtering out high-frequency noise before connecting to the speaker connector J10. The audio input is equipped with a microphone connector J41, whose signal lines are connected in parallel with ESD protection diodes ED35 and ED36 to effectively prevent static electricity generated when a person touches the microphone from damaging the internal chips.

[0022] In terms of peripheral expansion and debugging control, the RK3288's USB HOST interface connects to the peripheral expansion circuit, which includes the USB HUB controller chip U9. The U9's uplink port connects to the main controller, while its downlink port expands to multiple USB interface sockets. Each USB interface socket's data line is equipped with a low-capacitance ESD protection device, providing electrostatic protection while ensuring high-speed data transmission. Debugging is performed via the debugging serial port header J17, connected to the RK3288's UART2 interface. A series resistor is connected to the signal line, and ESD diodes ED29 and ED30 are used to ground it. In addition, the PCB features power, operating status, and custom LED indicators driven by GPIO pins through MOSFETs or transistors, as well as button control circuitry including a reset button KEY2, a power button KEY3, and a restore button KEY1. Each button's signal terminal is equipped with a pull-up resistor and parallel ESD protection diodes ED26, ED27, and ED28, thus forming a complete intelligent cabinet control system with high anti-interference performance. Example

[0023] This embodiment, based on embodiment 1, proposes a specific hardware structure relationship for an anti-interference intelligent cabinet control device. refer to Figure 2The power management circuit employs a multi-level anti-interference and protection design. After the external 12V DC power supply is connected through the power interface, it first passes through a self-resetting fuse F1 (MSMD300) connected in series in the positive circuit to cut off the circuit in case of abnormally high current. Simultaneously, a transient suppression diode ED1 (ESD9N12BA) is connected in parallel at the power input terminal, utilizing its avalanche breakdown characteristics to absorb external surge voltages. The power supply, after initial protection, passes through an input filter network composed of electrolytic capacitors C3, C4, and C5, and a ceramic capacitor C6, filtering out high-frequency noise on the power line. The smoothed DC power supply is then fed into a DC-DC buck converter circuit, which contains two similar buck branches, each composed of buck chips U2 and U3, both of which are MP1495S.

[0024] This embodiment takes the first buck circuit, which generates the system voltage VCC_SYS, as an example. The input pin of chip U2 is connected to the filtered 12V power supply. Its enable pin is connected to the power supply and control signal through a voltage divider network composed of resistors R6, R11, and R9, setting the turn-on threshold. The switching pin of chip U2 is connected to a power inductor L1, and the other end of inductor L1 is the output terminal. Through the energy storage effect of the inductor coil, and in conjunction with the filter capacitor group C8, C9, C10, and C11 connected in parallel at the output terminal, a smooth DC voltage is output. To maintain voltage stability, the voltage signal at the output terminal is connected to the feedback pin of chip U2 through a feedback voltage divider circuit composed of resistors R8 and R12. The chip automatically adjusts the switching duty cycle of the internal MOSFET according to the feedback voltage to achieve closed-loop voltage regulation. The second buck circuit is based on chip U3. It outputs a stable 5V voltage through power inductor L2 and a feedback network composed of resistors R15 and R21 to supply peripherals.

[0025] refer to Figure 3 The USB hub circuit is based on the USB HUB controller chip U9, which uses the FE1.1s or a similar high-performance hub chip. The clock signal for chip U9 is provided by a 12MHz passive crystal oscillator Y2 connected between the XIN and XOUT pins. The upstream data port of chip U9 is connected to the RK3288 main controller via differential signal lines, while the downstream port expands to multiple USB interfaces. To ensure signal integrity, 0.1uF decoupling capacitors, including C40, C42, C46, ​​and C48, are placed near the 3.3V and 1.8V power supply pins of chip U9. Furthermore, the circuit also features overcurrent detection. Overcurrent indication signals OVCJ1 and OVCJ5 are connected to the detection pins of chip U9 after passing through RC filter circuits composed of resistor R45 and capacitor C58, and resistor R43 and capacitor C57, respectively. Combined with low-capacitance ESD protection devices on the external USB interface data lines, this achieves efficient expansion and protection for USB peripherals.

[0026] refer to Figure 4 This device employs an HDMI display interface circuit, with the core connector being the HDMI interface socket J13. To ensure the integrity of high-frequency video signals during transmission and reduce electromagnetic radiation, the data transmission of J13 uses four sets of differential signal lines connected to the main control connection circuit. Specifically, pins 1 and 3 of J13 form the second set of data differential pairs; pins 4 and 6 form the first set of data differential pairs; pins 7 and 9 form the zeroth set of data differential pairs; and pins 10 and 12 form the clock differential pair. Furthermore, pin 13 of J13 connects to consumer electronics control signals, and pins 15 and 16 connect to the clock and data lines of the display data channel, respectively, for reading the EDID information of the display device.

[0027] Regarding power supply and electrical protection, pin 18 of J13 is connected to the system power supply VCC_SYS. To filter out high-frequency noise on the power line and prevent voltage fluctuations during hot-plugging from interfering with the internal circuitry, a 0.1uF filter capacitor C98 is connected in parallel with ground on this pin. Pin 19 of J13 is the hot-plug detection pin, used to provide feedback to the main controller on the connection status of the external display device. Meanwhile, to enhance the mechanical strength and grounding shielding of the interface, the fixed pins of the HDMI connector are reliably connected to the PCB's ground plane, thus providing a good signal return path for high-speed differential signals and effectively improving the anti-interference capability of the display interface.

[0028] refer to Figure 5The network communication circuit is an RJ45 interface socket J12 with an integrated network transformer, used to connect standard Ethernet cables. Four sets of differential signal lines MDI0_P / N, MDI1_P / N, MDI2_P / N, and MDI3_P / N from the onboard physical layer chip (PHY) are responsible for transmitting high-speed network data. To ensure communication quality in complex industrial or strong electromagnetic environments, these four signal lines are connected in series with external common-mode inductors FB25, FB26, FB27, and FB24 before being connected to the RJ45 interface socket J12. The differential pair MDI0_P / N is connected to the TD0+ / TD0- pins of J12 via common-mode inductor FB25; the differential pair MDI1_P / N is connected to the TD1+ / TD1- pins of J12 via common-mode inductor FB26; the differential pair MDI2_P / N is connected to the TD2+ / TD2- pins of J12 via common-mode inductor FB27; and the differential pair MDI3_P / N is connected to the TD3+ / TD3- pins of J12 via common-mode inductor FB24. Furthermore, the center tap pin of the transformer integrated inside the J12 interface socket is connected to signal ground via a 0.1uF capacitor C4615. The metal casing pins of the interface socket are directly connected to the chassis ground or the PCB protective ground. The integrated LED indicator is connected to the power and control signals via current-limiting resistors R711 and R712.

[0029] In this circuit, the externally connected common-mode inductors FB24-FB27 serve as the first line of defense, providing extremely high impedance to common-mode noise superimposed on the differential signal. This effectively suppresses common-mode interference induced by external electromagnetic fields on the cable from entering the system, while also preventing high-frequency noise from the system from radiating outwards through the network cable, with minimal attenuation of useful differential data signals. Secondly, the network transformer integrated within the RJ45 connector J12 provides electrical isolation, blocking the DC path between the external cable and the internal circuitry, preventing damage to the sensitive PHY chip from external high-voltage surges or ground potential differences. Thirdly, the center tap of the internal transformer is grounded through capacitor C4615, providing a low-impedance discharge path for common-mode noise on the cable side. Finally, the reliable grounding of the connector's metal casing ensures a shielded connection, guaranteeing the effective functioning of the shielded network cable's shielding layer and diverting interference coupled to the shielding layer to the ground. This design, combining external filtering, internal isolation and filtering, and robust grounding shielding, significantly improves the reliability and electromagnetic compatibility of network communication.

[0030] refer to Figure 6 In order to achieve reliable human-machine interaction control, this device is equipped with a high anti-interference button control circuit on the PCB substrate. The circuit mainly includes the restore button KEY1, the reset button KEY2 and the power button KEY3 and their matching signal conditioning and protection devices.

[0031] For the recovery button KEY1, its corresponding signal network is RECOVER. To prevent accidental triggering of system functions due to button bounce, the signal line is pulled up to the 1.8V power supply through a 10kΩ precision resistor R98 and connected to one end of button KEY1 via a 10Ω series resistor R99. At the connection point of resistors R98 and R99, a 1nF capacitor C99 is connected in parallel to ground. When the button is pressed or released, the RC low-pass filter network formed by R99 and C99 effectively absorbs high-frequency glitches generated by mechanical contact bounce, ensuring a smooth transition of the RECOVER signal. Simultaneously, an ESD5451R electrostatic discharge protection diode ED26 is connected in parallel at the button signal input to discharge electrostatic charges introduced when a person touches the button.

[0032] For the reset button KEY2, to accommodate multi-source reset requirements and prevent mutual interference between different reset signals, the circuit employs diode isolation logic. The MCU enable signal MCU_EN, the system reset signal RESET, and the peripheral reset signal PE_RST from the MCU are connected to the anodes of three Schottky diodes D9, D10, and D11 (model 1N5819) after passing through current-limiting resistors R102 (10Ω) and R103 (10Ω), respectively. The cathodes of these three diodes are connected to the reset network, enabling reset to be triggered by any signal source while preventing signal backflow using the unidirectional conduction characteristic of diodes. One end of the reset button KEY2 is connected to this reset network through a 0Ω resistor R681, and is also connected in parallel with an ESD5451R electrostatic discharge protection diode ED27, thereby improving the electromagnetic compatibility of the circuit while ensuring logical correctness.

[0033] For the power button KEY3, its control signal POWER_ON is connected to the main controller through a 51kΩ resistor R105. A 0Ω resistor R670 is connected in series in the button path, and an ESD5451R electrostatic protection diode ED28 is connected in parallel. In addition, for convenient external expansion and testing, connectors J14 and J15 are included in the circuit. J14 is used to bring out the recovery button and ADC signals, and its ADC_IN0 pin is pulled up to the 1.8V power supply through a 10kΩ resistor R100. Through the above design, utilizing RC filtering to eliminate jitter, diode isolation to prevent signal crosstalk, and TVS / ESD devices to clamp overvoltage, this button control circuit can maintain extremely high false trigger suppression and electrostatic protection capabilities in complex industrial environments.

[0034] refer to Figure 7This device also includes debugging and status indication circuitry on the PCB substrate. The debugging interface uses a 4-pin header J17, corresponding to power, ground, and serial port transmit / receive signals respectively. To prevent damage to the main control chip from electrostatic discharge or surges generated during the insertion and removal of external debuggers, ESD protection devices ED29 and ED30 (model ESD5451N) are connected to ground on the signal pins of J17 respectively. In the signal transmission path, the transmit signal UART2_TX is level-shifted and isolated through an N-channel MOSFET Q9 (model WNM6001). The drain and source of Q9 are pulled up to the IO power supply through 47kΩ resistors R109 and R108 respectively. The receive signal UART2_RX is connected through a series diode D15 (1N4148) and a pull-up resistor R116 (10kΩ), and clamping diodes D13, D14, and D16 further protect the internal circuitry, ensuring the safety and stability of debugging communication. The status indication circuit includes a custom indicator light DIY_LED and a working status indicator WORK_LED. These two signals are connected to NPN transistors Q17 and Q15 (both S8050 models) via 10kΩ base resistors R677 and R674, respectively. The transistors control the LED's on / off state, thus avoiding the LED drive current being directly borne by the main control GPIO pins and reducing interference to the main control logic level. Specifically, Q17 drives the green LED LED4, and Q15 drives the blue LED LED3. The LED anode power supply circuit uses P-channel MOSFETs Q18 and Q16 (model WPM2015-3 / TR) as power switches. Their gates are grounded and kept in a normally on state, their sources are connected to VCC_IO, and their drains are powered to the LEDs via 100Ω current-limiting resistors R679 and R607. 0.1uF capacitors C584 and C583 are connected in parallel at the power supply terminals to filter out power supply noise, achieving a highly reliable status display function.

[0035] refer to Figure 8To ensure pure audio output even in complex electromagnetic environments, this device employs a highly interference-resistant audio power amplifier circuit. The core of this circuit consists of two audio power amplifier chips, U101 and U102, both AW8733TQR, used to drive the left and right channel speakers respectively. To completely isolate the audio amplification from high-frequency ripple interference from the system power supply, the circuit uses an independent LC filter power supply design. The system power supply VCC_SYS_5V is not directly supplied to the power amplifier chip, but is divided into two paths: the first path passes through an LC low-pass filter composed of a surface-mount inductor L4 and a filter capacitor C126 (10uF / 10V) to generate a pure PA_5V voltage for U101; the second path passes through an LC low-pass filter composed of a surface-mount inductor L12 and a filter capacitor C127 (10uF / 10V) to generate a PA_5V1 voltage for U102. This power isolation design significantly reduces the noise floor. At the audio signal input, the left channel signal HPOL and the right channel signal HPOR from the main controller or codec are isolated from DC components by coupling capacitors C4651 (1uF) and C4656 (1uF), respectively. To further filter out high-frequency interference signals, an RC low-pass filter network is also set at the input. The left channel is input through resistor R722 (1K) and filtered by capacitor C4653 (220pF) to ground; the right channel is input through resistor R726 (1K) and filtered by capacitor C4654 (220pF) to ground. The enable terminal (SHDN) of the power amplifier chip is synchronously controlled by the control signal SPK_CTL through 10kΩ resistors R720 and R748 to eliminate power-on knock. At the audio signal output, the amplified signal is output through the 4-pin speaker connector J10. Pins 4 and 3 of J10 are connected to the left channel output, and pins 1 and 2 are connected to the right channel output. To prevent static electricity or surges introduced by the external speaker connection cable from damaging the expensive power amplifier chip, each signal line of the J10 interface socket is connected in parallel to ground with a bidirectional transient suppression diode, namely ED69, ED70, ED71, and ED72, all model ESD9N12BA. This comprehensive anti-interference and protection design at the power supply, signal input, and output ends ensures the long-term reliable operation of the smart cabinet's voice broadcast function.

[0036] refer to Figure 9The audio processing circuit also includes a microphone interface circuit, which connects to an external electret microphone via a 2-pin microphone socket J41. Pin 1 of J41 is connected to the microphone's positive signal line, and pin 2 is connected to the microphone's negative signal line. Considering that the microphone interface is a frequently touched component and easily susceptible to external static electricity, an ESD protection mechanism is implemented at the signal input stage: an ESD protection diode ED36 is connected in parallel between pin 1 and ground, and an ESD protection diode ED35 is connected in parallel between pin 2 and ground; the recommended model for both is ESD5451N. In the event of electrostatic discharge, these two diodes quickly conduct, discharging the high-voltage charge to ground, thereby protecting the downstream audio ADC chip from damage. Regarding signal conditioning and interference suppression, a sophisticated filtering network is designed along the signal path to filter out radio frequency interference and high-frequency environmental noise, ensuring recording clarity. Specifically, a 100pF capacitor C128 is connected in parallel between the two differential signal lines MICIN-P and MICIN-N to filter out differential-mode noise. Simultaneously, a 100pF capacitor C135 is connected in parallel to ground on the MICIN-P signal line, and a 100pF capacitor C133 is connected in parallel to ground on the MICIN-N signal line; these two capacitors are used to filter out common-mode noise. In addition, the circuit includes a bias voltage supply loop. The system analog power supply VCCA_3 first passes through an RC power filter circuit composed of resistor R136 (1kΩ) and two parallel-connected electrolytic capacitors C124 (22uF) and C125 (0.1uF) to obtain a clean DC bias voltage. This bias voltage is then applied to the MICIN-P signal line via resistor R137 (2.2kΩ), providing a stable static operating point for the microphone to function properly. This constitutes a complete audio input loop that combines protection and high fidelity characteristics.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. An anti-interference intelligent cabinet control device, characterized in that, The device includes a PCB substrate, and a main control connection circuit, a power management circuit, an audio processing circuit, an HDMI display interface circuit, a network communication circuit, and a peripheral expansion circuit disposed on the PCB substrate. The main control connection circuit is configured to connect to the RK3288 core board. The power management circuit is connected to an external DC power supply, which, after conversion, supplies power to the core board and each peripheral circuit. The signal terminals of the HDMI display interface circuit, the audio processing circuit, and the network communication circuit are respectively connected to the main control connection circuit. The peripheral expansion circuit includes a USB hub circuit, which is connected to the main control connection circuit via differential signal lines.

2. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The HDMI display interface circuit includes an HDMI interface socket J13; the four pairs of differential signal pins of the HDMI interface socket are all connected to the main control connection circuit; a pull-up resistor is connected between the hot-plug detection pin of the HDMI interface socket and the power supply terminal; a filter capacitor C98 is connected in parallel next to the power supply pin of the HDMI interface socket, and the ground terminal is connected to the PCB ground plane.

3. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The audio processing circuit includes power amplifier chips U101 and U102 and a speaker interface socket J10. The input terminal of the power amplifier chip is connected to the audio output pin of the main control connection circuit through a coupling capacitor. The output terminal of the power amplifier chip is connected to an LC filter circuit. The LC filter circuit includes inductors L4 and L12 connected in series and capacitors C126 and C127 connected in parallel to ground. The output terminal of the LC filter circuit is connected to the speaker interface socket.

4. The anti-interference intelligent cabinet control device according to claim 3, characterized in that, The audio processing circuit also includes a microphone interface circuit, which includes a microphone socket J41. ESD protection diodes ED35 and ED36 are connected in parallel on the signal line of the microphone socket to prevent external static electricity from damaging the internal circuit.

5. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The network communication circuit includes an RJ45 network transformer interface socket J12; the RJ45 network transformer interface socket is connected to four sets of differential signal lines, each set of differential signal lines is connected in series with a common-mode inductor to suppress common-mode noise interference, and the RJ45 network transformer interface socket integrates a network connection indicator and a data transmission indicator.

6. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The power management circuit includes DC-DC buck converter chips U2 and U3; the input terminal of the DC-DC buck converter chip is connected to a 12V DC power supply, and a transient suppression diode ED1 is connected in parallel at the input terminal; the output terminal of the DC-DC buck converter chip is connected to power inductors L1 and L2 and a filter capacitor bank, which are used to output a stable 5V voltage and system voltage.

7. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The USB hub circuit includes a USB HUB controller chip U9. The upstream port of the USB HUB controller chip is connected to the main control connection circuit, and the downstream port of the USB HUB controller chip is connected to multiple USB interface sockets. Each data line of the USB interface socket is equipped with a low-capacitance ESD protection device.

8. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The PCB substrate is also provided with a debugging and status indication circuit, which includes a debugging serial port header J17 and multiple sets of LED indicators. The signal lines of the debugging serial port header are connected in series with resistors and grounded through ESD diodes ED29 and ED30. The multiple sets of LED indicators include power indicators, working status indicators and custom indicators, which are connected to the GPIO pins of the main control connection circuit through MOSFET or transistor driving circuits.

9. The anti-interference intelligent cabinet control device according to claim 1, characterized in that, The PCB substrate is also provided with a button control circuit; the button control circuit includes a reset button KEY2, a power button KEY3 and a restore button KEY1, and the signal terminals of each button are connected in parallel with ESD electrostatic protection diodes ED26, ED27 and ED28, and are connected with pull-up resistors.

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