Internet of Things development board

Abstract

The utility model relates to the technical field of development boards, in particular to an internet of things development board, which comprises a master control module, a power management module, an eight-path digital quantity input interface module, an eight-path relay output control module, a communication interface module and an extended function module. And the power management module is electrically connected with the main control module, the eight-path digital quantity input interface module, the eight-path relay output control module, the communication interface module and the extended function module, supplies power to each module and realizes electrical isolation. Onboard eight-path relay output and eight-path digital input meet various industrial and intelligent control requirements. The communication interface module provides a path of RS485 interface and a path of POE network port, and supports diversified network and bus communication. The extended function module integrates an RTC real-time clock, an SD card slot interface and a buzzer alarm, and supports data recording, time management and acoustic alarm. According to the design, a hardware development platform with high integration and complete functions is provided for industrial Internet of Things application.

Description

TECHNICAL FIELD

[0001] The utility model relates to the development board technical field, especially relates to a thing networking development board. BACKGROUND

[0002] The thing networking control board on the market generally has the problems of single function, limited interface resource, poor expansibility and the like, and lacks power supply and signal isolation protection, in addition, the existing development board often only supports single mode in network communication, lacks integrated power supply and communication function such as power over Ethernet, and limits its applicability in complex application scenarios.

[0003] Therefore, a high-reliability thing networking development board with comprehensive functions, rich interfaces, isolation protection and multiple communication modes is urgently needed to promote the in-depth application of thing networking technology in industrial control and automation field. UTILITY MODEL CONTENT

[0004] To solve the above problems, the utility model provides a thing networking development board.

[0005] The utility model solves technical problem's scheme provides a development board, the development board includes host computer module, power management module, 8 way digital quantity input interface module, 8 way relay output control module, communication interface module and extension function module, the thing networking development board still includes 8 Extend IO pins, the host computer module includes a plurality of GPIO pins,

[0006] The power management module includes a variety of power isolation conversion circuit, and is connected with the host computer module, 8 way digital quantity input interface module, 8 way relay output control module, communication interface module and extension function module electrically,

[0007] 8 way digital quantity input interface module includes 8 IN pins, 8 way relay output control module includes 8 CH pins, 8 IN pins are connected with 8 GPIO pins in the host computer module electrically respectively, 8 CH pins are connected with 8 Extend IO pins electrically respectively,

[0008] The communication interface module includes an Ethernet interface module and an RS485 interface module, the Ethernet interface module includes Net class function pins, the Ethernet interface module is connected with the host computer module electrically through Net class function pins, the RS485 interface module includes TXD1 pin and RXD1 pin, the RS485 interface module is connected with the host computer module electrically through TXD1 pin and RXD1 pin,

[0009] The expansion function module includes an RTC real-time clock module, an SD card storage module and a buzzer alarm module, the RTC real-time clock module includes an I2C pin, and the RTC real-time clock module is electrically connected with the main control module through the I2C pin; the SD card storage module includes an SD type function pin, and the SD card storage module is electrically connected with the main control module through the SD type function pin, and the buzzer alarm module is signal connected with the main control module.

[0010] Preferably, the power management module includes three power supply units, including at least one of a POE power supply unit, a wide voltage DC input unit or a USB power supply unit.

[0011] Preferably, the main control module includes a main control circuit, an antenna circuit, a key control circuit and a USB communication circuit, the Internet of Things development board includes an antenna connecting seat, the antenna circuit is electrically connected with the antenna connecting seat, the main control circuit includes a GPIO0 pin and a CHIP_PU pin, and the main control circuit is electrically connected with the key control circuit through the GPIO0 pin and the CHIP_PU pin, and the main control circuit is electrically connected with the USB communication circuit through the GPIO pin.

[0012] Preferably, the plurality of power isolation conversion circuits include a step-down voltage stabilizing power supply circuit, a linear voltage stabilizing power supply circuit and a step-down switching power supply circuit, the step-down voltage stabilizing power supply circuit is electrically connected with the relay output control module, the RS485 interface module includes an RS485 bus circuit, the linear voltage stabilizing power supply circuit is electrically connected with the RS485 bus circuit, the Ethernet interface module includes an Ethernet signal processing and state indication circuit, and the step-down switching power supply circuit is electrically connected with the main control module, the Ethernet signal processing and state indication circuit and the expansion function module.

[0013] Preferably, the 8-way digital input interface module is provided with an optocoupler isolation and signal conditioning circuit, a 5V to 5V isolation power supply circuit, an 8-way digital input interface circuit and an upper pull resistance configuration circuit, the optocoupler isolation and signal conditioning circuit is electrically connected with the 5V to 5V isolation power supply circuit and the upper pull resistance configuration circuit, the optocoupler isolation and signal conditioning circuit includes a DIN COM terminal, the 8-way digital input interface circuit includes eight DIN pins, and the DIN COM terminal is a common loop end point of the eight DIN pins.

[0014] Preferably, the power management module supplies power and isolation to the main control module, the 8-way digital input interface module, the 8-way relay output control module, the communication interface module and the expansion function module through the three power supply units and the plurality of power isolation conversion circuits.

[0015] Preferably, the 8-channel relay output control module includes a relay drive circuit, a freewheeling protection circuit, and a status indicator circuit, which are electrically connected to the power management module.

[0016] Preferably, the RS485 interface module includes an isolated communication circuit, a serial communication status indicator circuit, an RS485 bus circuit, a signal ground isolation circuit, a lightning and surge protection circuit, and a TVS protection circuit. The isolated communication circuit includes TXD1 pin, RXD1 pin, TXD' pin, and RXD' pin. The isolated communication circuit is electrically connected to the serial communication status indicator circuit through the TXD1 pin and the RXD1 pin. The isolated communication circuit is electrically connected to the RS485 bus circuit through the TXD' pin and the RXD' pin. The RS485 bus circuit is electrically connected to the signal ground isolation circuit, the lightning and surge protection circuit, and the TVS protection circuit.

[0017] Preferably, the Ethernet interface module includes a PoE interface circuit, an Ethernet signal processing and status indication circuit, and a network LED power selection circuit. The PoE interface circuit includes RJ12, RJ36, RJ45, and RJ78 pins. The Ethernet signal processing and status indication circuit includes pins 5, 8, 10, and 9. The RJ12, RJ36, RJ45, and RJ78 pins are respectively connected to pins 5, 8, 10, and 9 of the Ethernet signal processing and status indication circuit J13. The status indicator circuit includes a status indicator light and an active status indicator light, which drive the corresponding LEDs through a MOSFET.

[0018] Preferably, the RTC real-time clock module includes an RTC_SCL pin and an RTC_SDA pin. The RTC real-time clock module is electrically connected to the main control module through the RTC_SCL pin and the RTC_SDA pin, and is equipped with a backup power supply U5. The SD card storage module supports two communication modes, SDIO and SPI, through pin multiplexing, and the buzzer alarm module drives the buzzer through a transistor.

[0019] Compared with existing technologies, the IoT development board of this utility model has the following advantages:

[0020] 1. This utility model's IoT development board integrates a main control module, multi-channel isolated digital input and relay output control, multiple communication methods, and extended functions into one, providing a highly integrated and fully functional hardware development platform for industrial IoT applications. The power management module includes multiple power isolation conversion circuits and is electrically connected to the main control module, 8-channel digital input interface module, 8-channel relay output control module, communication interface module, and extended function module, providing power to each module and achieving electrical isolation. The board features 8 onboard relay outputs and 8 onboard digital inputs to meet various industrial and intelligent control needs. The communication interface module provides one RS485 interface and one PoE port, supporting diverse network and bus communication. The extended function module integrates an RTC real-time clock, an SD card slot interface, and a buzzer alarm, supporting data logging, time management, and acoustic alarms. This design provides a highly integrated and fully functional hardware development platform for industrial IoT applications.

[0021] 2. The IoT development board provided by this utility model integrates three power management modules: a PoE power supply unit, a wide-voltage DC input unit, and a USB power supply unit. Through the integration and coordination of multiple power supply methods, this design significantly improves the power supply adaptability and flexibility of the device in different field environments, and reduces the risk of system interruption due to a single power supply failure.

[0022] 3. In the IoT development board provided by this utility model, the main control module, through a highly integrated design, organically integrates the main control, antenna, buttons, and USB communication circuit to form a fully functional and optimized IoT core. While providing complete wireless communication, user interaction, and wired debugging capabilities, it also ensures the flexibility and stability of wireless signal connection through the antenna connector. Reliable hardware reset and power management are achieved by using the buttons connected to the CHIP_PU pin. Combined with the buttons connected to specific GPIO and the USB circuit, the development board is endowed with powerful hardware control flexibility, convenient system debugging capabilities, and reliable and stable communication performance, significantly improving development efficiency and the reliability of the final product.

[0023] 4. In the IoT development board provided by this utility model, various power inputs and outputs are switched and regulated by multiple power isolation conversion circuits, ensuring that a clean and stable DC voltage can be provided to the subsequent circuits regardless of the method of obtaining power, avoiding mutual interference between different power paths, and improving the overall reliability and output voltage quality of the entire power system.

[0024] 5. The IoT development board provided by this utility model features an 8-channel digital input interface module that integrates optocoupler isolation and signal conditioning circuits, an independent 5V to 5V isolated power supply, a complete pull-up resistor configuration circuit, and a unified DINCOM common loop terminal. This achieves industrial-grade high-reliability electrical isolation and anti-interference capabilities, effectively protecting the main control circuit from high voltage, surges, and ground loop impacts in the field. At the same time, it ensures that various switching signals can be stably and accurately acquired and conditioned. Its unified common terminal design and flexible pull-up configuration greatly simplify external wiring and enhance the interface's compatibility with different sensors, significantly improving the adaptability and reliability of the entire IoT development board in harsh industrial environments.

[0025] 6. In the IoT development board provided by this utility model, the power management module supplies power and isolates the main control module, the 8-channel digital input interface module, the 8-channel relay output control module, the communication interface module, and the expansion function module through the three power supply units and the various power isolation conversion circuits. This design achieves precise power zoning management, providing safe isolated power for I / O interfaces that require electrical isolation from external high-voltage and high-current environments, effectively preventing field interference from entering the core system through the power path, and providing high-efficiency, low-cost power conversion for internal core circuits, avoiding unnecessary isolation losses. This zoning power supply strategy optimizes the efficiency and cost of the power supply solution while ensuring the overall system safety and anti-interference capability, achieving the best balance between safety and economy.

[0026] 7. In the IoT development board provided by this utility model, the 8-channel relay output control all include a drive circuit composed of transistors and a freewheeling protection circuit. This design uses a small-current GPIO signal to safely drive the relay coil, thereby controlling the on / off state of high-power loads; the freewheeling protection circuit can effectively absorb the reverse electromotive force generated when the relay coil is de-energized, protecting the drive components from damage and improving the drive reliability and service life of the output interface; the status indicator circuit synchronously indicates the relay status.

[0027] 8. The IoT development board provided by this utility model includes an RS485 interface module comprising an isolation communication circuit, a serial communication status indicator circuit, an RS485 bus circuit, a signal ground isolation circuit, a lightning and surge protection circuit, and a TVS protection circuit. Through a comprehensive design of isolation, filtering, status indication, and multiple protections, standard RS485 differential communication is achieved, possessing excellent common-mode interference immunity, suitable for long-distance transmission, meeting the needs of industrial fieldbus communication, and ensuring the reliability and stability of data transmission.

[0028] 9. In the IoT development board provided by this utility model, the Ethernet interface module includes a PoE interface circuit, an Ethernet signal processing and status indication circuit, and a network LED power selection circuit. The network transformer J13 plays the role of isolating Ethernet data signals and suppressing common-mode interference, ensuring the stability of data transmission. The status indicator light intuitively displays the network connection and data activity status, which facilitates quick diagnosis of network faults and improves the maintainability of the device's network functions and user experience.

[0029] 10. In the IoT development board provided by this utility model, the RTC real-time clock module communicates efficiently with the main control module via the I2C bus and is equipped with an independent backup power supply to ensure continuous and accurate timing even when the main power supply of the system is disconnected, providing a reliable time reference for data recording and event marking. Meanwhile, the SD card storage module supports both SDIO and SPI dual communication modes, greatly improving the flexibility of storage expansion and the compatibility of the main control interface resources. The buzzer alarm module adopts a transistor drive scheme, which is simple in structure, reliable in drive, and can promptly emit clear audible and visual warning signals. These three components work together to enhance the overall performance of the IoT development board in terms of data timeliness, storage adaptability, and on-site alarm capabilities. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a structural block diagram of the IoT development board provided in the first embodiment of this utility model.

[0032] Figure 2 This is a circuit structure diagram of the main control module of the Internet of Things development board provided in the first embodiment of this utility model.

[0033] Figure 3 This is a circuit diagram of the power management module of the Internet of Things development board provided in the first embodiment of this utility model.

[0034] Figure 4 This is a circuit diagram of the digital input interface module of the Internet of Things development board provided in the first embodiment of this utility model.

[0035] Figure 5 This is a circuit diagram of the relay output control module of the Internet of Things development board provided in the first embodiment of this utility model.

[0036] Figure 6This is a circuit diagram of the Ethernet interface module of the communication interface module of the IoT development board provided in the first embodiment of this utility model.

[0037] Figure 7 This is a circuit diagram of the RS485 interface module of the communication interface module of the IoT development board provided in the first embodiment of this utility model.

[0038] Figure 8 This is a circuit diagram of the RTC real-time clock module, an extended function module of the IoT development board provided in the first embodiment of this utility model.

[0039] Figure 9 This is a circuit diagram of the SD card storage module, an extended function module of the IoT development board provided in the first embodiment of this utility model.

[0040] Figure 10 This is a circuit diagram of the buzzer alarm module, an extended function module of the Internet of Things development board provided in the first embodiment of this utility model.

[0041] Figure 11 This is a pinout table showing the connections between the modules and the main control circuit of the IoT development board provided in the first embodiment of this utility model.

[0042] Explanation of reference numerals in the attached diagram:

[0043] 100. Internet of Things (IoT) development board;

[0044] 10. Main control module; 101. Main control circuit; 102. Antenna circuit; 103. Button control circuit; 104. USB communication circuit;

[0045] 20. Power Management Module; 201. Buck Regulated Power Supply Circuit; 202. Linear Regulated Power Supply Circuit; 203. Buck Switching Power Supply Circuit;

[0046] 30. Digital input interface module; 301. Optocoupler isolation and signal conditioning circuit; 302. 5V to 5V isolation power supply circuit; 303. Digital input interface circuit; 304. Pull-up resistor configuration circuit;

[0047] 40. Relay output control module;

[0048] 50. Communication interface module; 511. PoE interface circuit; 512. Ethernet signal processing and status indication circuit; 513. Network LED power selection circuit; 521. Isolation communication circuit; 522. Serial communication status indication circuit; 523. RS485 bus circuit; 524. Signal ground isolation circuit; 525. Lightning and surge protection circuit; 526. TVS protection circuit;

[0049] 60. Extended function module; 61. RTC real-time clock module; 621. TF card interface circuit; 622. Signal pull-up and multiplexing circuit; 63. Buzzer alarm module. Detailed Implementation

[0050] 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 accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0051] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0052] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0053] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this utility model according to the specific circumstances.

[0054] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0055] Please see Figure 1 , Figure 2 and Figure 11The first embodiment of this utility model provides an Internet of Things (IoT) development board 100, including a main control module 10, a power management module 20, an 8-channel digital input interface module 30, an 8-channel relay output control module 40, a communication interface module 50, and an expansion function module 60; the IoT development board 100 also includes eight Extend IO pins, namely Extend IO1, Extend IO2, Extend IO3, Extend IO4, Extend IO5, Extend IO6, Extend IO7, and Extend IO8; the main control module 10 includes multiple GPIO (General-Purpose I / O) pins. Input / Output (general purpose input / output) pins, including multiple GPIO pins: GPIO4, GPIO5, GPIO6, GPIO7, GPIO8, GPIO9, GPIO10, GPIO11, GPIO12, GPIO13, GPIO14, GPIO15, GPIO16, GPIO17, GPIO18, GPIO19, GPIO20, GPIO21, GPIO39, GPIO40, GPIO41, GPIO42, GPIO45, GPIO47, and GPIO48; the power management module 20 includes multiple... A power isolation conversion circuit is provided and electrically connected to the main control module 10, the 8-channel digital input interface module 30, the 8-channel relay output control module 40, the communication interface module 50, and the expansion function module 60. The 8-channel digital input interface module 30 includes 8 IN pins, and the 8-channel relay output control module 40 includes 8 CH pins. The 8 IN pins, namely IN1, IN2, IN3, IN4, IN5, IN6, IN7, and IN8, are electrically connected to GPIO4 to GPIO11 pins in the main control module 10, respectively. The 8 CH pins, namely CH1, CH2, CH3, CH4, CH5, CH6, CH7, and CH8, are electrically connected to Extend... The IO1 pin is electrically connected to the Extend IO8 pin; the communication interface module 50 includes an Ethernet interface module and an RS485 interface module. The Ethernet interface module includes Net-class function pins Net_INTn, Net_MOSI, Net_MISO, Net_SCLK, Net_SCSn, and Net_RSTn. The Ethernet interface module is electrically connected to the main control module 10 through the Net-class function pins.The RS485 interface module includes TXD1 and RXD1 pins, which are electrically connected to the main control module 10. The extended function module 60 includes an RTC real-time clock module 61, an SD card storage module, and a buzzer alarm module 63. The RTC real-time clock module 61 includes an I2C pin, which is electrically connected to the main control module 10. The SD card storage module includes SD-type function pins, which are electrically connected to the main control module 10. The buzzer alarm module 63 is signal-connected to the main control module 10.

[0056] Optionally, the extended function module 60 includes at least one of an RTC (Real-Time Clock) module, an SD card storage module, and a buzzer alarm module 63. As an optional implementation, in this embodiment, the extended function module 60 includes three types: an RTC (Real-Time Clock) module, an SD card storage module, and a buzzer alarm module 63. Specifically, the RTC module 61 is electrically connected to the GPIO40 to GPIO42 pins of the main control module 10 via I2C (Inter-Integrated Circuit) pins; the SD (Secure-Digital) card storage module is electrically connected to the GPIO pins of the main control module 10 via SD-type function pins; and the buzzer alarm module 63 is controlled by the main control circuit 101 via the GPIO46 pin.

[0057] Understandably, this development board can use a high-performance ESP32-S3 microcontroller as its core, with a built-in Xtensa 32-bit LX7 dual-core processor with a main frequency of up to 240MHz. It supports 2.4GHz Wi-Fi and BLE (Bluetooth Low Energy) dual-mode communication, boasts superior RF performance, and enjoys broad open-source ecosystem support. Integrating control, power, input / output, communication, and expansion functions, it constitutes a complete IoT node hardware platform, meeting the needs of industrial applications for multi-signal acquisition, device control, and reliable communication.

[0058] Specifically, the main control module 10 uses an ESP32-S3 series high-performance microcontroller, responsible for system control, data processing, and network protocol stack operation. The power management module 20 provides stable power to each functional module. Eight digital input interfaces are used to acquire external switching signals, and eight relay outputs control high-power loads. Ethernet and RS485 interfaces provide wired and industrial bus communication capabilities. An RTC module provides precise timing, an SD card module supports data storage, and a buzzer module provides audible alarms. All modules are integrated onto a single PCB, resulting in a compact structure. They can be mounted on a 35mm standard DIN rail using a DIN rail-mounted ABS (Acrylonitrile Butadiene Styrene) protective housing, facilitating installation and integration in industrial environments.

[0059] Please see Figure 2 , Figure 3 , Figure 6 and Figure 11 The power management module 20 includes three power supply units, which include at least one of a PoE power supply unit, a wide voltage DC input unit, or a USB power supply unit.

[0060] Understandably, by integrating and coordinating multiple power supply methods, this design significantly improves the power supply adaptability and flexibility of the equipment in different field environments, and reduces the risk of system interruption due to a single power supply failure.

[0061] Specifically, the PoE power supply unit has a 5V power supply and GND. The IoT development board 100 includes power terminals, a wide-voltage DC input unit electrically connected to the power terminals, and a USB power supply unit electrically connected to the main control module 10 via GPIO19 and GPIO20. The power management module 20 provides three flexible power supply methods, greatly improving the device's environmental adaptability and deployment convenience. The PoE power supply unit can be selected to use a PoE module conforming to the IEEE 802.3af standard to achieve Ethernet power supply functionality, simplifying wiring; the wide-voltage DC input unit connects to the power terminals on the board, supporting a wide input range of 7-36V; the USB power supply unit provides power and communication via a Type-C interface. The internal circuitry automatically switches and regulates the voltage, outputting a uniform 5V or 3.3V voltage.

[0062] Please see Figure 2The main control module 10 includes a main control circuit 101, an antenna circuit 102, a button control circuit 103, and a USB communication circuit 104. The IoT development board 100 includes an antenna connector. The antenna circuit 102 is electrically connected to the antenna connector. The main control circuit 101 includes a GPIO0 pin and a CHIP_PU pin. The main control circuit 101 is electrically connected to the button control circuit 103 through the GPIO0 pin and the CHIP_PU pin. The main control circuit 101 is also electrically connected to the USB communication circuit 104 through the GPIO pin.

[0063] Understandably, the antenna circuit 102 includes an IPEX antenna interface, enabling a highly reliable, low-loss connection with an external antenna. This effectively improves the signal reception sensitivity and transmission stability of wireless communication, making it particularly suitable for high-frequency, high-bandwidth IoT applications such as Wi-Fi and Bluetooth. It provides an "antenna connection path" for the ESP32-S3's main control module 10, facilitating signal transmission and reception. The main control module 10 includes a button control circuit 103. R32 (10KΩ) provides a pull-up resistor for the GPIO0 pin. By default, the GPIO0 pin is high, booting from flash memory and executing normal firmware. When the Key1 Boot button is pressed, GPIO0 goes low, entering "download mode" (Bootloader mode), allowing for firmware flashing via USB using a download tool. R33 (10KΩ) provides a pull-up resistor for CHIP_PU. When the Key2 reset button is pressed, CHIP_PU goes low, resetting the chip due to the loss of the enable signal. After releasing the button, CHIP_PU returns to high, restarting the chip, which can be used to restart the system or recover from an abnormal state. The main control module 10 also includes a USB communication circuit 104, with D_P (positive USB data line) connected to the GPIO20 pin and D_N (negative USB data line) connected to the GPIO19 pin. The ESP32-S3 can simulate USB functionality through these two pins for program downloading (firmware burning) or USB communication with a host computer.

[0064] Please see Figure 3 The system includes multiple power isolation conversion circuits, including a step-down regulated power supply circuit 201, a linear regulated power supply circuit 202, and a step-down switching power supply circuit 203. The step-down regulated power supply circuit 201 is electrically connected to the relay output control module 40. The RS485 interface module includes an RS485 bus circuit 523, and the linear regulated power supply circuit 202 is electrically connected to the RS485 bus circuit 523. The Ethernet interface module includes an Ethernet signal processing and status indication circuit 512, and the step-down switching power supply circuit 203 is electrically connected to the main control module 10, the Ethernet signal processing and status indication circuit 512, and the extended function module 60.

[0065] Understandably, power isolation conversion circuits can employ different isolation chips to achieve varying degrees of isolation. By using multiple power isolation conversion circuits, efficiency and safety are balanced, ensuring that regardless of the power source, a clean and stable DC voltage is provided to subsequent circuits. This avoids mutual interference between different power paths, improving the overall reliability and output voltage quality of the entire power system.

[0066] Specifically, the step-down regulated power supply circuit 201 includes three parts: 1. Input protection section: Terminal J4 is used to connect to an external power supply. D5 (1N5819) is a diode that prevents reverse connection of the power supply and protects the subsequent circuits. D8 (SMAJ40CA) is a transient voltage suppression diode that can suppress instantaneous high-voltage pulses and protect the circuit from surge voltage impacts. C24 and C28 are electrolytic capacitors used for input filtering and stabilizing the input voltage. 2. Power conversion section: 71-XL1509-ADJE1 is a DC-DC step-down converter that converts the input voltage to the required output voltage by adjusting the on and off times of the internal switching transistor. R30 and R31 form a feedback circuit used to set the output voltage value, and C16 is a compensation capacitor for the feedback circuit. 3. Output filtering section: L2 is a power inductor that, together with capacitors C23, C29, C30, and C31, forms an LC filter circuit to filter out ripple in the output voltage, making the output 5V voltage more stable and smooth. D6 is also a diode, serving a protective function. U8 (B0505S-WR2) is an isolated power supply module that isolates the 5V voltage and outputs Relay-5V to drive loads such as relays, ensuring electrical isolation between different circuits.

[0067] The linear regulated power supply circuit 202 uses the ME6217C33M5G linear regulator chip as its core to convert the input voltage into a stable output voltage. The linear regulated power supply circuit 202 consists of three parts: 1. Input section: The input voltage Relay-5V is connected. C26, C27, and C36 are input filter capacitors, whose function is to filter out high-frequency noise and ripple in the input voltage, stabilizing the input voltage. 2. Regulation section: The ME6217C33M5G is a low-dropout linear regulator. It stabilizes the output voltage at 3.3V by adjusting its own voltage drop. Compared to switching power supplies, linear regulated power supplies have lower output voltage noise, making them suitable for circuits sensitive to power supply noise. 3. Output section: C34 and C35 are output filter capacitors, further filtering out residual ripple in the output voltage, providing a stable Relay-3V3 output. This is mainly used to power loads with high power quality requirements, such as the core power supply of some chips. In addition, the circuit distinguishes between GND and SGND (signal ground) to help reduce signal interference.

[0068] The step-down switching power supply circuit 203 uses the MP1605GTF-Z as its core power conversion chip to convert the input voltage down to a stable 3.3V output. The step-down switching power supply circuit 203 consists of three parts: 1. Input filtering section: With a 5V input voltage, C4 and C5 are input filter capacitors. C4 is an electrolytic capacitor used to filter low-frequency ripple, and C5 is a ceramic capacitor used to filter high-frequency noise. Together, they make the input voltage cleaner. 2. Power conversion section: The MP1605GTF-Z is a DC-DC step-down switching power supply chip. R1, R11, and R4 form a feedback circuit to precisely regulate the output voltage, stabilizing it at 3.314V. The EN pin is the enable pin, pulled up to 5V through R1 to ensure normal chip operation. 3. Output filtering section: L1 is a power inductor, which, together with C6 and C7, forms an LC filter circuit to filter out ripple in the output voltage, making the output 3.3V voltage more stable. In addition, LED1 (red light-emitting diode) and R2 (5.1K resistor) are connected in series in the circuit. LED1 can be used as a power indicator light and will light up when the power supply is working properly. R2 acts as a current limiter to prevent LED1 from being damaged due to excessive current.

[0069] Please see Figure 2 and Figure 4 and Figure 11 The 8-channel digital input interface module 30 includes an optocoupler isolation and signal conditioning circuit 301, a 5V to 5V isolated power supply circuit 302, an 8-channel digital input interface circuit 303, and a pull-up resistor configuration circuit 304. The optocoupler isolation and signal conditioning circuit 301 is electrically connected to the 5V to 5V isolated power supply circuit 302 and the pull-up resistor configuration circuit 304. The optocoupler isolation and signal conditioning circuit 301 includes a DIN COM terminal, and the 8-channel digital input interface circuit 303 includes 8 DIN pins. The DIN COM terminal is the common loop endpoint of the 8 DIN pins.

[0070] Understandably, this design not only achieves electrical isolation between external signals and the internal main control circuit 101, effectively preventing high-voltage interference from entering, but also ensures the stability of the input signal through pull-up and filtering. Combined with the status indicator lights on each channel, it provides great convenience for on-site debugging and equipment status monitoring.

[0071] Specifically, the 8-channel digital input interface module 30 includes pins IN1 to IN8, which are electrically connected to pins GPIO4 to GPIO11 of the main control module 10, respectively. Optocouplers U6 and U10 are "electrical-optical-electrical" isolation devices, which electrically isolate externally input digital signals from the internal circuitry of the system, improving anti-interference capability and safety. Resistors R23 and R27 (5.1KΩ) act as pull-up and current-limiting resistors to stabilize the input level; capacitors C14 and C15 (100nF) are filter capacitors to remove high-frequency noise from the input signal and prevent false triggering; resistors R24 and R28 (470R) are current-limiting resistors for the optocoupler's LEDs, ensuring that the optocoupler operates within a safe current range.

[0072] U2 is an isolated DC-DC power supply module. Its input is the system's 5V power supply, and its output is an isolated DIN-5V. Capacitors C9 (10uF) and C10 (100nF) are input filter capacitors, stabilizing the input voltage and filtering out ripple; capacitors C11 (100nF) and C12 (10uF) are output filter capacitors, further stabilizing the isolated 5V output voltage. The function of this circuit is to provide an independent and isolated power supply to the digital input side, ensuring that the digital input section has no direct electrical connection to the system's main power supply, preventing external high voltage, noise, etc., from entering the system, and ensuring system safety and anti-interference capabilities.

[0073] J2 is a 10-pin terminal block with a spacing of 5.08mm. DIN1-DIN8 are 8 digital input channels, and DIN COM is the common terminal. External digital signals are connected to the system through this terminal block, which is the physical interface for the entire 8-channel digital input interface module to interact with external devices.

[0074] The pull-up resistor configuration circuit 304 consists of multiple sets of R141 (10KΩ)-R148 (10KΩ). These 10KΩ resistors can be used as pull-up resistors to pull the corresponding pins IN1-IN8 up to the 3V3 power supply, ensuring that the pins can maintain a stable high level when there is no external input signal, preventing false triggering and other problems caused by floating level, and improving the stability and reliability of the circuit.

[0075] Please see Figure 1 and Figure 3 The power management module 20 supplies power and isolates the main control module 10, the 8-channel digital input interface module 30, the 8-channel relay output control module 40, the communication interface module 50, and the expansion function module 60 through three power supply units and multiple power isolation conversion circuits.

[0076] Understandably, this design achieves precise power zoning management, providing safe isolated power to I / O interfaces that require electrical isolation from external high-voltage, high-current environments, effectively preventing field interference from entering the core system through the power path. Simultaneously, it provides high-efficiency, low-cost power conversion for internal core circuits, avoiding unnecessary isolation losses. This zoned power supply strategy optimizes the efficiency and cost of the power supply solution while ensuring overall system safety and anti-interference capabilities, achieving the best balance between safety and economy.

[0077] Specifically, the power management module 20 offers three flexible power supply methods, greatly improving the device's environmental adaptability and deployment convenience. The PoE power supply unit can be selected to implement Ethernet power supply functionality via a PoE module compliant with the IEEE 802.3af standard, simplifying wiring; the wide-voltage DC input unit connects to the onboard power terminals, supporting a wide input range of 7-36V; the USB power supply unit provides power and communication via a Type-C interface. Internal circuitry enables automatic switching and voltage regulation, outputting a uniform 5V or 3.3V voltage. Additionally, the MP1605GTF-Z is a high-efficiency synchronous buck DC-DC converter used for 5V to 3.3V voltage conversion, powering most of the system motherboard circuitry. The B0505LS-1W is an isolated DC-DC power module with electrical isolation between its input and output sides, used to provide power to components requiring isolated power supply, such as optocouplers for digital input interfaces.

[0078] Please see Figure 5 and Figure 11 The 8-channel relay output control module 40 includes a relay drive circuit, a freewheeling protection circuit, and a status indicator circuit. The relay drive circuit, freewheeling protection circuit, and status indicator circuit are electrically connected to the power management module 20.

[0079] Understandably, the drive circuit enables the low-power GPIO signals of the main control MCU (Microcontroller Unit) to reliably control the relay coil, and can also be triggered remotely via cloud commands; the freewheeling protection circuit eliminates the threat of reverse induced electromotive force generated when the inductive load is de-energized, protects the drive components, and improves the drive reliability and service life of the output interface; the status indicator circuit synchronously indicates the relay status.

[0080] Specifically, taking the first channel as an example, the SS8050 transistor T1 receives the control signal from the J6A interface. When the control signal is high, T1 conducts, providing input current to the PC817 optocoupler U12. The internal LED of the optocoupler U12 lights up, and the phototransistor on the right side conducts, providing a Relay-5V power supply path for the relay coil P1. When the coil is energized, the internal contacts close, realizing the "connection" of the external high-voltage circuit; when the coil is de-energized, the contacts open, and the circuit is "disconnected." When the coil is de-energized, the reverse electromotive force forms a circuit through the freewheeling diode D9, thereby protecting the transistor T1 and optocoupler U12 from being damaged by high voltage. When the optocoupler U12 conducts, the 3V3 power supply, after being current-limited by R57 and R59, lights up LED10 (green).

[0081] The 8-channel relay output control module 40 includes pins CH1 to CH8, which are electrically connected to pins Extend IO1 to Extend IO8, respectively. Each relay driver circuit includes a transistor, and the GPIO controls the transistor's on / off state through a base resistor, thereby controlling the current in the relay coil. The freewheeling protection circuit consists of a diode connected in reverse parallel across the relay coil, providing a discharge path for the induced current generated in the coil when power is off.

[0082] Please see Figure 2 , Figure 7 and Figure 11 The RS485 interface module includes an isolation communication circuit 521, a serial communication status indicator circuit 522, an RS485 bus circuit 523, a signal ground isolation circuit 524, a lightning and surge protection circuit 525, and a TVS protection circuit 526. The isolation communication circuit 521 includes TXD1 pin, RXD1 pin, TXD' pin, and RXD' pin. The isolation communication circuit 521 is electrically connected to the serial communication status indicator circuit 522 through the TXD1 pin and the RXD1 pin. The isolation communication circuit 521 is electrically connected to the RS485 bus circuit 523 through the TXD' pin and the RXD' pin. The RS485 bus circuit 523 is electrically connected to the signal ground isolation circuit 524, the lightning and surge protection circuit 525, and the TVS protection circuit 526.

[0083] Understandably, the RS485 interface can be replaced by a CAN interface. The dedicated RS485 chip U23 reliably converts UART (Universal Asynchronous Receiver / Transmitter) signals to RS485 differential signals, supporting long-distance, multi-node industrial bus communication. RS485 supports industrial protocols such as Modbus and can connect to RS485 devices such as temperature and humidity meters and energy meters for data acquisition and control. Simultaneously, TVS diodes effectively suppress overvoltages from surges and lightning strikes on the communication line, significantly improving the reliability, stability, and survivability of remote communication in harsh industrial environments.

[0084] Specifically, the RS485 interface module is electrically connected to the GPIO17 and GPIO18 pins of the main control module 10 via the TXD1 and RXD1 pins. The RS485 interface module includes an isolation communication circuit 521, a serial communication status indicator circuit 522, an RS485 bus circuit 523, a signal ground isolation circuit 524, a lightning and surge protection circuit 525, and a TVS protection circuit 526.

[0085] In the isolated communication circuit 521, the π141E61 type isolation chip U23 is the core component, enabling bidirectional conversion between serial port signals (TXD1, RXD1) and RS485 differential signals. Simultaneously, through an internal isolation mechanism, it electrically isolates the system side (powered by 3V3, GND ground) from the RS485 bus side (powered by Relay-3V3, SGND ground), effectively preventing high-voltage, noise, and other interference signals from the RS485 bus side from entering the system side, thus improving the system's anti-interference capability and security. Capacitors C57 and C58 are 100nF filter capacitors used to stabilize the power supply voltage, filter out power supply ripple, and ensure stable chip operation.

[0086] In the serial communication status indicator circuit 522, LED19 (green) is connected to the TXD1 signal. When the system sends data to the RS485 bus, TXD1 outputs a valid level, and LED19 lights up. LED20 (blue) is connected to the RXD1 signal. When the system receives data from the RS485 bus, RXD1 inputs a valid level, and LED20 lights up. R137 and R139 are 0Ω resistors, mainly used for current limiting and wire connection to ensure that the LED operating current is within a safe range, while also connecting the signal and LED loops.

[0087] In RS485 bus circuit 523, the SP3485EN class chip U24 is a half-duplex RS485 transceiver chip responsible for converting the system's serial port signals (RS485_TXD, RS485_RXD) into RS485 differential signals (A, B bus), or converting RS485 differential signals into serial port signals recognizable by the system. D19 (SMAJ6.5CA), D22 (SMAJ12CA), and D23 (SMAJ12CA) are transient voltage suppressor diodes (TVS). When the RS485 bus (RS485A-2, RS485B-2) encounters lightning strikes or surge voltages, the TVS will quickly break down, clamping the voltage to a safe value, thus protecting subsequent circuits. R132 and R136 are 4.7KΩ matching resistors used to reduce signal reflections on the RS485 bus and improve signal integrity during long-distance transmission. F1 and F2 (BSMD1206-050) are self-resetting fuses. When the bus current is too large (such as when a short circuit occurs), the resistance of the fuse will rise sharply, cutting off the current and protecting the bus and interface circuits.

[0088] In the signal ground isolation circuit 524, capacitor C62 has a capacitance of 1nF and a withstand voltage of 2KV. In RS485 communication, common-mode interference signals may be conducted through the line. This capacitor can provide a low-impedance path for common-mode interference signals, filter out high-frequency common-mode noise between SGND and Earth, reduce the impact of common-mode interference on RS485 communication signals, and improve signal purity and communication stability.

[0089] In the 525 surge protection circuit, D18 is a ceramic gas discharge tube used to protect the RS485 bus from high-voltage transient impacts. When lightning, power surges, or other high-voltage surges occur on the RS485 bus, the discharge tube quickly conducts when the high voltage reaches its breakdown voltage, releasing the surge energy through the Earth (ground wire), thereby protecting the downstream RS485 transceiver chip and related circuits from damage.

[0090] The SM712-type TVS diode array D21 in the TVS protection circuit 526 provides transient overvoltage protection between the RS485 bus and protective ground. When the bus encounters instantaneous high-voltage surges such as lightning strikes or electrostatic discharges, D21 will quickly activate (avalanche breakdown), clamping the abnormal common-mode overvoltage to a safe level and dissipating the surge energy through the Earth path, thereby protecting the downstream RS485 interface chip and circuit from damage.

[0091] Please see Figure 2 , Figure 6 and Figure 11The Ethernet interface module includes a PoE interface circuit 511, an Ethernet signal processing and status indication circuit 512, and a network LED power selection circuit 513. The PoE interface circuit 511 includes RJ12, RJ36, RJ45, and RJ78 pins. The Ethernet signal processing and status indication circuit 512 includes pins 5, 8, 10, and 9. The RJ12, RJ36, RJ45, and RJ78 pins are respectively connected to pins 5, 8, 10, and 9 of J13 in the Ethernet signal processing and status indication circuit 512. The status indicator circuit includes a status indicator light and an active status indicator light, which drive the corresponding LEDs through a MOSFET.

[0092] Understandably, in the PoE interface circuit 511, H1 is the Ethernet interface, and RJ12, RJ36, RJ45, and RJ78 are the interface pins used to transmit Ethernet data signals. Simultaneously, the circuit introduces a 5V power supply and GND to support PoE functionality, meaning it can transmit both data and power via an Ethernet cable. This allows for the simultaneous power supply to PoE-enabled devices such as network cameras and wireless access points, eliminating the need for additional power cables and facilitating device deployment and installation. This design transmits both data and power via the network cable, while the indicator light circuit visually displays the network link status and data activity, aiding in network debugging and fault diagnosis.

[0093] Specifically, the Ethernet interface module is electrically connected to the GPIO12 to GPIO16 pins of the main control module 10 via Net-class function pins. In the Ethernet signal processing and status indication circuit 512, the 100Mbps RJ45 with POE HBJ-6117ANL network transformer J13 isolates Ethernet data signals and suppresses common-mode interference, ensuring stable data transmission. Capacitors C25 and C54 are used for filtering to stabilize power supply or signal voltage; resistors R153 and R154 are used for voltage division and current limiting to condition the signal and make it meet the requirements of subsequent circuits. A circuit composed of MOSFETs Q1 and Q3 (AO3401) and resistors R125 and R113 drives the ACTLED (activity status indicator) and LINKLED (link status indicator). When there is data activity or a link is established on the Ethernet network, the corresponding indicator lights up, visually displaying the Ethernet's operating status. In addition, related circuits drive green and yellow network status LEDs (Net_GreenLED and Net_YellowLED) to further enrich the display of the Ethernet's operating status.

[0094] The network LED power selection circuit 513 is used to select the power supply for the network status LED. The circuit has two power inputs: 3V3 and 5V. By using NC OR in conjunction with resistor R158 (0R), it selects whether to use the 3V3 or 5V power supply to power Net_LED_VCC, thus providing the appropriate operating voltage for the network status LED and ensuring that the LED lights up normally to display the network status.

[0095] Please see Figure 2 , Figure 8 , Figure 9 , Figure 10 and Figure 11 The RTC real-time clock module 61 includes an RTC_SCL pin and an RTC_SDA pin. The RTC real-time clock module 61 is electrically connected to the main control module 10 through the RTC_SCL pin and the RTC_SDA pin, and is equipped with a backup power supply U5. The SD card storage module supports two communication modes, SDIO and SPI, through pin multiplexing. The buzzer alarm module 63 drives the buzzer through a transistor.

[0096] Understandably, the RTC's backup battery ensures that time information is not lost in the event of a main power failure; the SD card interface can select between high-speed SDIO mode or the more compatible SPI mode via pin multiplexing to adapt to different storage needs and card types.

[0097] Specifically, the RTC real-time clock module 61 is electrically connected to the GPIO40 to GPIO42 pins of the main control module 10 through the I2C pin, the SD card storage module is electrically connected to the GPIO pins of the main control module 10 through the SD class function pins, and the buzzer alarm module 63 is controlled by the main control circuit 101 through the GPIO46 pin.

[0098] The RTC chip can be the PCF85063ATL chip U3, which offers high timing accuracy and extremely low power consumption. The chip is powered by a 3V3 power supply. D2 (B5819WS) is a diode, used here to prevent reverse connection and protect the chip from damage. C13 (1uF) is a power supply filter capacitor, used to stabilize the power supply voltage, filter out ripple and noise, and ensure the chip operates in a stable power environment. The chip communicates with the main controller via the I2C bus (SCL - clock line, SDA - data line), and an external 32.768kHz crystal oscillator Y1 provides a precise clock reference. RTC_INT is the interrupt output pin of U3. When the chip's alarm, timer, or other functions are triggered, this pin outputs a corresponding interrupt signal to notify the main controller chip to perform related processing. The backup power supply U5 (RTC6603SP) is connected to the main power supply via a diode. It is in a floating charge state when the main power supply is normal, and automatically and seamlessly switches to power the chip when the main power supply is disconnected, ensuring continuous clock operation and maintaining the continuity of event recording.

[0099] In the TF card interface circuit 621, the TF-07F card slot J14 is used to insert a TF card for data storage or read / write operations. SDIO_D0 to SDIO_D3 are the data pins of the SDIO bus, supporting high-speed data transmission (SDIO mode); SDIO_CMD is the command pin of the SDIO bus, used for command or response interaction between the host and the TF card; SDIO_SCK is the clock pin of the SDIO bus, providing a synchronization clock; VDD (3V3) is the power supply pin of the TF card, supplying power to the card; VSS (GND) is the ground pin, ensuring a potential reference; CD is the card detection pin, pulled up to 3V3 via R107. When a card is inserted, the CD level changes, triggering the host to detect whether the TF card is inserted. In the signal pull-up and multiplexing circuit 622, R117 (10KΩ) to R126 (10KΩ) provide a pull-up path to 3V3 for the SDIO pins, ensuring that the pins are at a high level when idle, enhancing signal stability and anti-interference capabilities. The TF card interface circuit 621 includes the SD_CS pin, SD_MISO pin, SD_MOSI pin, and SD_SCLK pin. These four pins are standard SPI communication pins, respectively connected to the GPIO21, GPIO45, GPIO47, and GPIO48 pins of the main control circuit 101. This circuit, through pin multiplexing, enables the TF card to support both SDIO high-speed mode and SPI low-speed mode, improving compatibility with different host devices.

[0100] The buzzer alarm module 63 can communicate with the GPIO46 pin of the main control circuit 101 via electrical signals. Buzzer B1 is the sound-generating element; when current flows through it, the internal diaphragm vibrates to produce sound, used for audible and visual prompts such as alarms and status feedback. The 8050 transistor Q2 acts as an electronic switch; when pin 1 receives a high-level signal, the transistor is saturated and conducts, providing a current path for the buzzer; when pin 1 is low, the transistor is cut off, and the buzzer is powered off. The RB521S-30 Zener diode D4 is used to stabilize the voltage across the buzzer and suppress reverse electromotive force. R49 (1KΩ) is a base current-limiting resistor, limiting the base current of the transistor to prevent excessive current from burning out the transistor. R50 (4.7KΩ) is a base pull-down resistor, ensuring that the base of the transistor is low when there is no signal, avoiding false triggering. R34 (0Ω) is a power supply path resistor (which can actually be considered a wire), providing a 3V3 power supply path for the buzzer.

[0101] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An Internet of Things (IoT) development board, characterized in that: The IoT development board includes a main control module, a power management module, an 8-channel digital input interface module, an 8-channel relay output control module, a communication interface module, and an expansion function module; the IoT development board also includes 8 Extend IO pins; the main control module includes multiple GPIO pins; The power management module includes multiple power isolation conversion circuits and is electrically connected to the main control module, the 8-channel digital input interface module, the 8-channel relay output control module, the communication interface module, and the expansion function module. The 8-channel digital input interface module includes 8 IN pins, and the 8-channel relay output control module includes 8 CH pins. The 8 IN pins are electrically connected to the 8 GPIO pins in the main control module, and the 8 CH pins are electrically connected to the 8 Extend IO pins. The communication interface module includes an Ethernet interface module and an RS485 interface module. The Ethernet interface module includes Net class function pins and is electrically connected to the main control module through the Net class function pins. The RS485 interface module includes TXD1 pins and RXD1 pins and is electrically connected to the main control module through the TXD1 pins and RXD1 pins. The extended function module includes an RTC real-time clock module, an SD card storage module, and a buzzer alarm module. The RTC real-time clock module includes an I2C pin and is electrically connected to the main control module through the I2C pin. The SD card storage module includes SD-type function pins and is electrically connected to the main control module through the SD-type function pins. The buzzer alarm module is signal-connected to the main control module.

2. The IoT development board according to claim 1, characterized in that: The power management module includes three power supply units, which include at least one of a PoE power supply unit, a wide voltage DC input unit, or a USB power supply unit.

3. The IoT development board according to claim 1, characterized in that: The main control module includes a main control circuit, an antenna circuit, a button control circuit, and a USB communication circuit. The IoT development board includes an antenna connector, and the antenna circuit is electrically connected to the antenna connector. The main control circuit includes a GPIO0 pin and a CHIP_PU pin, and the main control circuit is electrically connected to the button control circuit through the GPIO0 pin and the CHIP_PU pin. The main control circuit is also electrically connected to the USB communication circuit through the GPIO pin.

4. The IoT development board according to claim 2, characterized in that: The multiple power isolation conversion circuits include a buck regulator circuit, a linear regulator circuit, and a buck switching power supply circuit. The buck regulator circuit is electrically connected to the relay output control module. The RS485 interface module includes an RS485 bus circuit. The linear regulator circuit is electrically connected to the RS485 bus circuit. The Ethernet interface module includes an Ethernet signal processing and status indication circuit. The buck switching power supply circuit is electrically connected to the main control module, the Ethernet signal processing and status indication circuit, and the extended function module.

5. The IoT development board according to claim 1, characterized in that: The 8-channel digital input interface module includes an optocoupler isolation and signal conditioning circuit, a 5V to 5V isolated power supply circuit, an 8-channel digital input interface circuit, and a pull-up resistor configuration circuit. The optocoupler isolation and signal conditioning circuit is electrically connected to the 5V to 5V isolated power supply circuit and the pull-up resistor configuration circuit. The optocoupler isolation and signal conditioning circuit includes a DIN COM terminal. The 8-channel digital input interface circuit includes 8 DIN pins, and the DIN COM terminal is the common loop endpoint of the 8 DIN pins.

6. The IoT development board according to claim 4, characterized in that: The power management module supplies power and isolates the main control module, the 8-channel digital input interface module, the 8-channel relay output control module, the communication interface module, and the expansion function module through the three power supply units and the various power isolation conversion circuits.

7. The IoT development board according to claim 1, characterized in that: The 8-channel relay output control module includes a relay drive circuit, a freewheeling protection circuit, and a status indicator circuit. The relay drive circuit, freewheeling protection circuit, and status indicator circuit are electrically connected to the power management module.

8. The IoT development board according to claim 1, characterized in that: The RS485 interface module includes an isolated communication circuit, a serial communication status indicator circuit, an RS485 bus circuit, a signal ground isolation circuit, a lightning and surge protection circuit, and a TVS protection circuit. The isolated communication circuit includes TXD1 pin, RXD1 pin, TXD' pin, and RXD' pin. The isolated communication circuit is electrically connected to the serial communication status indicator circuit through the TXD1 pin and the RXD1 pin. The isolated communication circuit is electrically connected to the RS485 bus circuit through the TXD' pin and the RXD' pin. The RS485 bus circuit is electrically connected to the signal ground isolation circuit, the lightning and surge protection circuit, and the TVS protection circuit.

9. The IoT development board according to claim 1, characterized in that: The Ethernet interface module includes a PoE interface circuit, an Ethernet signal processing and status indication circuit, and a network LED power selection circuit. The PoE interface circuit includes RJ12, RJ36, RJ45, and RJ78 pins. The Ethernet signal processing and status indication circuit includes pins 5, 8, 10, and 9. The RJ12, RJ36, RJ45, and RJ78 pins are respectively connected to pins 5, 8, 10, and 9 of the Ethernet signal processing and status indication circuit J13. The status indicator circuit includes a status indicator light and an active status indicator light, which drive the corresponding LEDs through a MOSFET.

10. The IoT development board according to claim 1, characterized in that: The RTC real-time clock module includes an RTC_SCL pin and an RTC_SDA pin. The RTC real-time clock module is electrically connected to the main control module through the RTC_SCL pin and the RTC_SDA pin, and is equipped with a backup power supply U5. The SD card storage module supports two communication modes, SDIO and SPI, through pin multiplexing. The buzzer alarm module drives the buzzer through a transistor.

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