Multi-channel USB flash disk switching circuit structure

Abstract

The invention discloses a multichannel USB flash disk switching circuit structure, which relates to the technical field of data storage equipment, and comprises at least one main control substrate and a plurality of expansion substrates, and the main control substrate and the expansion substrates are completely consistent in structure and circuit. Each substrate is integrated with a USB input and output module, a USB-HUB expansion module, a single-chip microcomputer control module, an RS485 communication module, a USB power supply control protection module, a state indicating lamp module and an address dial switch module, and all the modules are electrically connected according to function requirements. The circuit adopts a multi-layer PCB and USB differential impedance matching design, a plurality of substrates are connected in series through an RS485 communication module, an external control device sends a control instruction, and independent switching of a plurality of USB interfaces is realized by a single-chip microcomputer control module in combination with substrate addresses of an address dial switch module. The structure adapts to a multi-U-disk batch data processing scene, solves the problems of low manual plugging efficiency and unstable signal transmission, and is convenient to maintain and high in safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data storage devices, and particularly to a multi-channel USB flash disk switching circuit structure. BACKGROUND

[0002] In the fields of data acquisition, industrial data management, and automated test systems, the demand for data switching connection of multiple USB flash disks is widespread. For example, in industrial fields, multiple USB flash disks are needed to store real-time monitoring data of different sensors; in laboratory automated test scenarios, the USB interfaces of multiple terminal devices need to be tested for compatibility and the test logs need to be exported through USB flash disks; and in industrial data management, the running logs of dozens to hundreds of USB flash disks need to be read in batches to complete data aggregation and analysis. These scenarios all require selective data reading and writing between multiple USB flash disks and host computers (computers or servers), and need to ensure operation efficiency and data transmission reliability.

[0003] Current implementation methods for multiple USB flash disk data switching have obvious defects. Traditional solutions mainly rely on manual plugging and unplugging of USB flash disks, and the operator needs to manually insert different USB flash disks one by one into the USB interface of the host computer to complete data interaction. On the one hand, this method is extremely inefficient, and when more than dozens of USB flash disks need to be processed, a single plugging and unplugging operation takes about 10-30 seconds, and the overall process cannot meet the timeliness requirements of batch data processing. On the other hand, frequent plugging and unplugging can cause mechanical wear and tear of the USB interface and the host computer USB interface, and usually more than 1000 times of manual plugging and unplugging can cause poor contact of the interface, shortening the service life of the hardware. At the same time, manual operation is prone to errors such as incorrect plugging of USB flash disks, direct plugging without executing the safe removal process, and other errors, which can cause data loss, damage to the USB flash disk file system, and other problems.

[0004] To improve the shortcomings of manual operation, multi-interface USB data reading devices appear on the market. Such devices realize interface expansion through the integration of USB-HUB chips and can connect multiple USB flash disks at the same time. However, the existing devices still have many technical limitations: first, the number of interfaces is limited. Most devices only support 4, 8 or 16 USB interface expansion, and the maximum number of interfaces does not exceed 32, which cannot meet the demand for connecting and independently switching 256 USB flash disks or more in industrial automation, large-scale testing and other scenarios; second, the signal transmission stability is poor. Some devices use single-layer or double-layer PCB board design and do not optimize the impedance matching for USB 3.0 high-speed differential signals (transmission rate up to 5Gbps). The signals are prone to reflection, attenuation or crosstalk during transmission, resulting in an increase in data transmission error rate and even transmission interruption; third, the maintainability is low. The main control unit and the expansion unit of the existing devices often use different circuit designs. When a unit fails, special parts need to be replaced, and the circuit differences between different units increase the difficulty of troubleshooting; fourth, the protection mechanism is imperfect. Most devices do not configure independent power control and protection circuits for each USB output interface. When a single interface appears abnormal such as short circuit, overcurrent (such as U disk internal short circuit leading to current exceeding 2A), etc., the whole device will be powered off, affecting the work of other normal interfaces, and the safety and reliability are insufficient.

[0005] In summary, the existing multi-USB flash disk data switching scheme cannot meet the needs of large-scale and high-reliability application scenarios in terms of operation efficiency, interface expansion capability, transmission stability, maintainability and safety. There is an urgent need for a circuit structure that can realize efficient switching of multiple USB flash disks, stable transmission and high maintainability and safety. SUMMARY

[0006] The purpose of the present application is to provide a multi-channel USB flash disk switching circuit structure to solve the problems of low efficiency, interface damage and high risk of misoperation caused by manual plugging in the prior art, to realize efficient and accurate switching control of multiple USB flash disks, to ensure data transmission stability, to improve device maintainability and safety, and to meet the needs of multi-USB flash disk batch data processing in industrial data acquisition, automated testing and other scenarios.

[0007] To achieve the above purpose, the present application provides a multi-channel USB flash disk switching circuit structure, which includes a plurality of substrates, at least one main control substrate and a plurality of expansion substrates among the plurality of substrates, and the main control substrate and the expansion substrate have the same structure and identical circuit; Each main control substrate and expansion substrate integrates a USB input and output module, a USB-HUB expansion module, a single-chip microcomputer control module, an RS485 communication module, a USB power control and protection module, a status indicator light module and an address dial switch module, The single-chip microcomputer control module is electrically connected with the RS485 communication module, the USB power control protection module, the USB-HUB expansion module and the address dial switch module respectively, the USB-HUB expansion module is electrically connected with the USB input and output module respectively, and the state indicator light module is electrically connected with the USB power control protection module, the USB input and output module and the RS485 communication module respectively.

[0008] Preferably, the circuit carrier of each substrate is a multilayer PCB board; and the wiring corresponding to the USB input and output module and the USB-HUB expansion module on the PCB board adopts a USB differential impedance matching design.

[0009] Preferably, the USB input and output module comprises one USB 3.0 input interface and a plurality of USB 3.0 output interfaces. The USB 3.0 input interface is a USB3.0-B type interface, and the differential signal pins thereof are electrically connected with the USB-HUB expansion module after being connected in series with a filter capacitor. The USB 3.0 output interface is a USB3.0-A type interface, and the power pins thereof are electrically connected with the output end of the USB power control protection module, and the signal pins thereof are electrically connected with the output end of the USB-HUB expansion module.

[0010] Preferably, the USB-HUB expansion module comprises a plurality of VL817-Q7 type USB-HUB chips, and each USB-HUB chip is configured with one W25X05CL type storage chip. The plurality of USB-HUB chips are arranged in cascade, the input end of the first-stage USB-HUB chip is electrically connected with the differential signal pins of the USB3.0-B type interface, and the output end of the last-stage USB-HUB chip is electrically connected with the signal pins of the USB3.0-A type interface. The SPI communication pins of the W25X05CL type storage chip are electrically connected with the corresponding pins of the corresponding USB-HUB chip one by one, and the core power supply end of the USB-HUB chip is connected with a DC3_3V power supply, and the logic power supply end is connected with a DC1_1V power supply.

[0011] Preferably, the single-chip microcomputer control module adopts an STM32F103RCT6 type single-chip microcomputer, and is matched with an SP706SEN type reset / watchdog chip and an SN74LVC1G66 type signal switch chip. The UART serial port pin of the STM32F103RCT6 model single-chip microcomputer is electrically connected with the RS485 communication module, the GPIO enabling pin is electrically connected with the enabling end of the USB power supply control protection module, and the GPIO detection pin is electrically connected with the address dial switch module; the reset pin of the SP706SEN model reset / watchdog chip is electrically connected with the reset pin of the STM32F103RCT6 model single-chip microcomputer, and the watchdog input pin is connected with a watchdog control signal; and the control pin of the SN74LVC1G66 model signal switch chip is electrically connected with the PB8 pin of the STM32F103RCT6 model single-chip microcomputer.

[0012] Preferably, the RS485 communication module comprises an SP3485EE model differential transmission chip, a 120Ω matching resistor and an SMBJ6.5CA model TVS protection tube. The data input pin of the SP3485EE model differential transmission chip is electrically connected with the UART sending pin of the single-chip microcomputer, and the data output pin is electrically connected with the UART receiving pin of the single-chip microcomputer. The 120Ω matching resistor is connected in parallel with the output end of the SP3485EE model differential transmission chip, and the SMBJ6.5CA model TVS protection tube is connected in series between the SP3485EE model differential transmission chip and the RS485 communication module of other substrates.

[0013] Preferably, the USB power supply control protection module comprises a plurality of G547G2TB1U model control protection chips, and the G547G2TB1U model control protection chip corresponds to the USB3.0-A type interface one by one. The enabling pin of the G547G2TB1U model control protection chip is electrically connected with the GPIO enabling pin of the single-chip microcomputer, and the overcurrent detection pin is electrically connected with the overcurrent detection pin of the single-chip microcomputer. Each substrate is powered by a unified BUS-5V external DC power supply, and the BUS-5V external DC power supply is used to power the USB-HUB expansion module, the single-chip microcomputer control module and the USB input / output module after being divided and filtered.

[0014] Preferably, the status indicator light module comprises a plurality of red USB power indicator lights, a plurality of green USB flash drive insertion indicator lights and a set of double-color RS485 serial transceiver indicator lights. The anode of the red USB power indicator light is electrically connected with the power output pin of the G547G2TB1U model control protection chip, and the cathode is connected to ground through a current limiting resistor. The anode of the green USB flash drive insertion indicator light is electrically connected with the state feedback pin of the single-chip microcomputer, and the cathode is connected to ground through a current limiting resistor. In the double-color RS485 serial port transceiver indicating lamp, the anode of the red LED is electrically connected with the sending pin of the SP3485EE type differential transmission chip, the anode of the green LED is electrically connected with the receiving pin of the SP3485EE type differential transmission chip, and the cathodes of the red LED and the green LED are grounded through current-limiting resistors.

[0015] Preferably, the address dial switch module adopts a multi-bit dial switch, each dial unit of the multi-bit dial switch corresponds to one level output end, each level output end is electrically connected with one GPIO detection pin of the single-chip microcomputer in one-to-one mode, and the multi-bit dial switch supports configuration of address codes of 0-31.

[0016] Preferably, a plurality of substrates are sequentially connected through respective RS485 communication modules, the RS485 communication modules are used for receiving control instructions sent by an external control device and transmitting the control instructions to the single-chip microcomputer control module, and the single-chip microcomputer control module realizes independent switching of a plurality of USB interfaces in combination with the substrate addresses of the address dial switch module.

[0017] According to the specific embodiments of the present application, the following technical effects are disclosed: 1. Multi-channel high-efficiency switching, adapting to large-scale scene requirements The mode innovation from manual plugging to automatic precise switching is realized, the multi-channel USB flash disk can be independently gated and controlled, the efficiency bottleneck of traditional manual operation is completely eliminated, the large-scale multi-USB flash disk data processing scene such as industrial data acquisition and automatic testing can be efficiently adapted, and the overall data interaction efficiency is greatly improved.

[0018] 2. High-speed stable transmission, ensuring data transmission integrity Multi-layer PCB differential impedance matching design is adopted, and the signal optimization function of the special USB-HUB chip is used, so that the reflection, attenuation and crosstalk problems in high-speed signal transmission are effectively avoided, the stable transmission of USB high-speed data in the multi-channel expansion link is ensured, the integrity of the data reading and writing process is ensured, and the high reliability requirement of industrial data storage is met.

[0019] 3. Unified substrate design, reducing whole-cycle maintenance cost All substrates adopt the same circuit architecture, realizing standardization and batch production, and in the equipment maintenance stage, the substrates can be replaced without difference, without distinguishing functional units, greatly simplifying the fault diagnosis and maintenance process, and significantly reducing the maintenance difficulty and cost of the whole life cycle of the equipment.

[0020] 4. Independent protection mechanism, improving system operation safety Each USB output interface is equipped with independent power supply control and protection circuit, with multiple protection functions such as overcurrent, overheat and reverse current, when an abnormality occurs in a single interface, only the independent power supply of the interface is cut off, without affecting the normal work of other interfaces, effectively avoiding the spread of single point failure, at the same time, the interface state is intuitively fed back through the independent indicator light, reducing the risk of misoperation, and ensuring the safe and reliable operation of the whole system.

[0021] The technical solutions of the present application will be further described in detail below with the help of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The system topology block diagram of the multi-channel U disk switching circuit structure embodiment of the present application is shown in the figure. Figure 2 The single substrate circuit block diagram of the embodiment of the present application is shown in the figure. Figure 3 The USB-HUB circuit principle diagram of the embodiment of the present application is shown in the figure. Figure 4 The single-chip microcomputer circuit principle diagram of the embodiment of the present application is shown in the figure. Figure 5 The RS485 communication circuit principle diagram of the embodiment of the present application is shown in the figure.

[0024] Reference signs 1, main control substrate; 2, expansion substrate; 3, power supply port; 4, RS485 communication port; 5, USB input port; 6, USB power indicator light; 7, U disk insertion indicator light; 8, USB output port; 9, dial switch. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with the help of the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with the help of the drawings and specific embodiments.

[0027] EMBODIMENT The embodiment is applied to an industrial production line data acquisition system, and needs to batch store and read real-time running logs of 256 sensor nodes. Each sensor node is matched with a USB flash disk (for locally caching logs), and needs to realize independent data read-write control of any USB flash disk through an upper computer (an industrial control computer) to avoid low efficiency, interface wear and tear and data loss problems caused by manual plugging and unplugging, and to ensure signal transmission stability in a complex electromagnetic environment of a workshop.

[0028] As shown in Figure 1 A multi-channel USB flash disk switching circuit structure includes 17 substrates, 1 main control substrate 1 and 16 extension substrates 2 are included in the 17 substrates, the main control substrate 1 and the extension substrate 2 are the same in structure and the same in circuit, and the circuit connection modes of the USB-HUB chip, the power port 3, the single-chip microcomputer, the RS485 communication port 4, the USB power control, the USB input port 5, the USB output port 8 and the protection circuit of each substrate are the same. The circuit carriers of each substrate are 4-layer PCB boards, and the wiring corresponding to the USB 3.0 input interface, the USB-HUB chip and the USB 3.0 output interface on the PCB board adopts a USB differential impedance matching design.

[0029] All the substrates are connected in series through RS485 interfaces to form a communication link, and a special control software running on a computer sends control instructions to the single-chip microcomputer of a specified substrate according to the substrate address through an RS485 communication protocol to realize opening and closing operations of any one of 256 USB interfaces. The USB 3.0 input interface of each substrate is connected with the USB 3.0 interface of the upper computer (computer or server), and the USB 3.0 output interface is used to connect the USB flash disk. Through the architecture, independent switching control of 256 USB flash disks (17 substrates x 16 channels / substrate) can be realized.

[0030] As shown in Figures 2-5 The circuit of a single substrate includes the following core modules, and the hardware connection and function of each module are as follows: 1. USB input and output module, including: Input interface: 1 USB 3.0-B type interface, used for connecting the USB 3.0 port of the upper computer, the differential signal pins (SSTX0±, SSRX0±) are connected with the input end of the first-level chip of the USB-HUB expansion module after filtering capacitors to filter out high-frequency interference to ensure 5Gbps high-speed transmission; Output interface: 16 USB 3.0-A type interfaces, each corresponding to a USB flash disk of a sensor node, the power pins are electrically connected with the output end of the corresponding chip in the USB power control protection module, and the signal pins are electrically connected with the output end of the last-level chip of the USB-HUB expansion module to support hot plugging of the USB flash disk.

[0031] 2. USB-HUB expansion module Core chip: 2 VL817-Q7 type USB-HUB chip cascade is adopted, the input end of the first stage chip is connected with the differential signal pin of USB3.0-B type interface, the output end of the last stage chip is connected with the signal pin of USB3.0-A type output interface in 16 ways, realizing 16-way USB expansion; Matching storage: each VL817-Q7 chip is configured with a W25X05CL type storage chip, the SPI communication pins (CS, SO, SI, CLK) of the storage chip are electrically connected with the corresponding pins of the VL817-Q7 chip one by one, which is used for storing the configuration parameters of the HUB; Power supply and control: the core power supply end (such as VCC33M, VCC33_L1~L4) of VL817-Q7 chip is connected with DC3.3V power supply, the logic power supply end (such as VCC11_L1~L4) is connected with DC1.1V power supply, and the SPICS pin is grounded through resistance, which cooperates with the SPI pin of the single-chip microcomputer to realize the read and write of configuration parameters.

[0032] 3. Single-chip microcomputer control module Main control chip: STM32F103RCT6 type single-chip microcomputer is adopted as the control core of the substrate, the UART serial port pin is electrically connected with the differential transmission chip of the RS485 communication module, which is used for receiving the control instructions of the upper computer; the GPIO enable pin is electrically connected with the enable end of each chip in the USB power control protection module, which is used for controlling the power on-off of the USB output interface; the GPIO detection pin is electrically connected with the address dial switch module and the overcurrent detection end of the USB power control protection module, realizing address recognition and abnormal detection. Auxiliary chip: SP706SEN type reset / watchdog chip is matched, the reset pin ( / RESET) is electrically connected with the reset pin (NRST) of STM32F103RCT6, the watchdog input pin (WDI) is connected with the watchdog control signal to prevent program from being stuck; at the same time, SN74LVC1G66 type signal switch chip is matched, the control pin is electrically connected with the GPIO pin of STM32F103RCT6, which is used for controlling the gating of key signal path, ensuring the accuracy of control logic.

[0033] 4. RS485 communication module Core chip: SP3485EE type differential transmission chip is adopted, the data input pin (DI) is electrically connected with the UART sending pin (TX) of STM32F103RCT6, the data output pin (RO) is electrically connected with the UART receiving pin (RX) of STM32F103RCT6, realizing the conversion between TTL signal and RS485 differential signal; Auxiliary elements: 120Ω matching resistance in parallel with the output of SP3485EE (A, B pins) to eliminate signal reflection; SMBJ6.5CA type TVS protection tube in series between SP3485EE and other substrate RS485 communication module to suppress surge interference and adapt to electromagnetic compatibility requirements in industrial environment 5. USB power control and protection module Core chip: contains 16 pieces of G547G2TB1U type control protection chip, corresponding to 16-way USB3.0-A type output interface, the enable pin of each chip is electrically connected with the GPIO enable pin of STM32F103RCT6, and the overcurrent detection pin is electrically connected with the overcurrent detection pin of STM32F103RCT6. When abnormal conditions such as short circuit and overcurrent occur in the corresponding USB interface, the chip can quickly cut off the power of the interface and feed back signals to the single-chip microcomputer, avoiding the spread of faults. Power supply logic: each substrate uses a unified BUS-5V external DC power supply, which is converted to DC3.3V and DC1.1V by the voltage dividing and filtering circuit inside the substrate, respectively powering the USB-HUB expansion module, single-chip microcomputer control module, and USB input and output module. Each power supply branch is connected in series with a self-resetting fuse, further improving power supply safety.

[0034] 6. Indicator light module USB power indicator light 6: 16 red LEDs, the anode of each LED is electrically connected with the power output pin of the corresponding G547G2TB1U chip, and the cathode is connected to ground through a current-limiting resistor. The LED lights up to indicate that the corresponding USB interface power is normal. U disk insertion indicator light 77: 16 green LEDs, the anode of each LED is electrically connected with the status feedback pin of STM32F103RCT6, and the cathode is connected to ground through a current-limiting resistor. The LED lights up to indicate that the corresponding USB interface has recognized the U disk. RS485 serial transceiver indicator light: a set of dual-color LEDs, the anode of the red LED is electrically connected with the transmission pin of SP3485EE, and the anode of the green LED is electrically connected with the reception pin of SP3485EE. The cathodes of both are connected to ground through current-limiting resistors. The red LED lights up to indicate that the module is sending instructions, and the green LED lights up to indicate that the module is receiving instructions.

[0035] 7. Address dial switch module The 5-position dial switch 9 is adopted, each dial unit corresponds to one level output end, and each level output end is electrically connected with the GPIO detection pin of the STM32F103RCT6 one by one, the on-off combination of the dial unit can configure the address code of 0-31, 17 baseboards are respectively configured with unique addresses (for example, the address of the main control baseboard 1 is 00001, and the addresses of the first to sixteenth expansion baseboards 2 are 00010-10000 in turn), so that the host computer can accurately locate the target baseboard.

[0036] The 17 baseboards are sequentially connected through the respective RS485 communication modules to form a bus type topology; the first end (the RS485 interface of the main control baseboard 1) is connected with the USB port of the host computer through the RS485-USB converter, the last end (the RS485 interface of the sixteenth expansion baseboard 2) is connected with a 120Ω matching resistor in parallel, so as to enhance the stability of long-distance communication; the USB3.0-B type input interface of all baseboards is connected in parallel to the USB3.0 expansion card of the host computer through the USB3.0 shielding line, the host computer is configured with 4-way USB3.0 output, each way is connected with the input interface of 4-5 baseboards, so as to guarantee sufficient data transmission bandwidth; the U disk of 256 sensor nodes is respectively inserted into the USB3.0-A type output interface of the 17 baseboards, the anti-falling buckle type USB line is adopted between the U disk and the interface, so as to adapt to the workshop vibration environment and avoid accidental disconnection.

[0037] The remaining technical features in the above embodiments can be flexibly selected by those skilled in the art according to actual conditions to meet different specific actual needs. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the protection scope of the appended claims of the present application. In the above description, a large number of specific details are set forth in order to provide a thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application does not have to be implemented with these specific details. In other examples, in order not to obscure the present application, well-known technologies such as specific construction details, operating conditions and other technical conditions are not specifically described.

[0038] The principles and implementation modes of the present application are described by applying specific examples, the above embodiment description is only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In view of the above, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A multi-channel USB flash drive switching circuit structure, characterized in that: It includes several substrates, among which at least one main control substrate and several extension substrates are included. The main control substrate and the extension substrates have the same structure and completely identical circuits. Each main control board and expansion board integrates a USB input / output module, a USB-HUB expansion module, a microcontroller control module, an RS485 communication module, a USB power control and protection module, a status indicator module, and an address DIP switch module. The microcontroller control module is electrically connected to the RS485 communication module, the USB power control and protection module, the USB-HUB expansion module, and the address DIP switch module. The USB-HUB expansion module is electrically connected to the USB input / output module. The status indicator module is electrically connected to the USB power control and protection module, the USB input / output module, and the RS485 communication module.

2. The multi-channel USB flash drive switching circuit structure according to claim 1, characterized in that: The circuit carrier of each substrate is a multi-layer PCB board; the traces on the PCB board corresponding to the USB input / output module and USB-HUB expansion module adopt USB differential impedance matching design.

3. The multi-channel USB flash drive switching circuit structure according to claim 2, characterized in that: The USB input / output module includes one USB 3.0 input interface and several USB 3.0 output interfaces; The USB 3.0 input interface is a USB 3.0-B type interface, and its differential signal pins are electrically connected to the USB-HUB expansion module after being connected in series with a filter capacitor. The USB 3.0 output interface is a USB 3.0-A type interface, with its power pins electrically connected to the output terminal of the USB power control and protection module, and its signal pins electrically connected to the output terminal of the USB-HUB expansion module.

4. The multi-channel USB flash drive switching circuit structure according to claim 3, characterized in that: The USB-HUB expansion module includes multiple levels of VL817-Q7 USB-HUB chips, with each level of USB-HUB chip corresponding to one W25X05CL memory chip; The multi-level USB-HUB chips are cascaded. The input terminal of the first-level USB-HUB chip is electrically connected to the differential signal pin of the USB 3.0-B interface, and the output terminal of the last-level USB-HUB chip is electrically connected to the signal pin of the USB 3.0-A interface. The SPI communication pin of the W25X05CL model memory chip is electrically connected to the corresponding pin of the corresponding USB-HUB chip, and the core power supply terminal of the USB-HUB chip is connected to a DC3_3V power supply, while the logic power supply terminal is connected to a DC1_1V power supply.

5. The multi-channel USB flash drive switching circuit structure according to claim 4, characterized in that: The microcontroller control module uses an STM32F103RCT6 microcontroller and is equipped with an SP706SEN reset / watchdog chip and an SN74LVC1G66 signal switch chip. The UART serial port pin of the STM32F103RCT6 microcontroller is electrically connected to the RS485 communication module, the GPIO enable pin is electrically connected to the enable terminal of the USB power control and protection module, and the GPIO detection pin is electrically connected to the address DIP switch module; the reset pin of the SP706SEN reset / watchdog chip is electrically connected to the reset pin of the STM32F103RCT6 microcontroller, and the watchdog input pin is connected to the watchdog control signal; the control pin of the SN74LVC1G66 signal switch chip is electrically connected to the GPIO pin of the STM32F103RCT6 microcontroller.

6. The multi-channel USB flash drive switching circuit structure according to claim 5, characterized in that: The RS485 communication module includes an SP3485EE differential transmission chip, a 120Ω matching resistor, and an SMBJ6.5CA TVS protection tube. The data input pin of the SP3485EE differential transmission chip is electrically connected to the UART transmit pin of the microcontroller, and the data output pin is electrically connected to the UART receive pin of the microcontroller. The 120Ω matching resistor is connected in parallel to the output terminal of the SP3485EE differential transmission chip, and the SMBJ6.5CA TVS protection tube is connected in series between the SP3485EE differential transmission chip and the RS485 communication module of other substrates.

7. The multi-channel USB flash drive switching circuit structure according to claim 6, characterized in that: The USB power control and protection module includes several G547G2TB1U model control and protection chips, and each G547G2TB1U model control and protection chip corresponds to a USB 3.0-A interface. The enable pin of the G547G2TB1U control and protection chip is electrically connected to the GPIO enable pin of the microcontroller, and the overcurrent detection pin is electrically connected to the overcurrent detection pin of the microcontroller. Each substrate is powered by a uniform BUS-5V external DC power supply. After voltage division and filtering, the BUS-5V external DC power supply powers the USB-HUB expansion module, the microcontroller control module, and the USB input / output module respectively.

8. The multi-channel USB flash drive switching circuit structure according to claim 7, characterized in that: The status indicator module includes several red USB power indicators, several green USB flash drive insertion indicators, and a set of dual-color RS485 serial port transceiver indicators. The anode of the red USB power indicator is electrically connected to the power output pin of the G547G2TB1U control and protection chip, and the cathode is grounded through a current-limiting resistor. The anode of the green USB flash drive insertion indicator is electrically connected to the status feedback pin of the microcontroller, and the cathode is grounded through a current-limiting resistor; In the dual-color RS485 serial port transceiver indicator, the anode of the red LED is electrically connected to the transmit pin of the SP3485EE differential transmission chip, and the anode of the green LED is electrically connected to the receive pin of the SP3485EE differential transmission chip. The cathodes of both the red and green LEDs are grounded through current-limiting resistors.

9. The multi-channel USB flash drive switching circuit structure according to claim 8, characterized in that: The address DIP switch module uses a multi-bit DIP switch. Each DIP unit of the multi-bit DIP switch corresponds to one level output terminal. Each level output terminal is electrically connected to the GPIO detection pin of the microcontroller. The multi-bit DIP switch supports the configuration of address codes from 0 to 31.

10. The multi-channel USB flash drive switching circuit structure according to claim 9, characterized in that: Several substrates are connected in series via their respective RS485 communication modules. The RS485 communication modules are used to receive control commands sent by external control devices and transmit the control commands to the microcontroller control module. The microcontroller control module, in conjunction with the substrate address of the address DIP switch module, enables independent switching of multiple USB interfaces.

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