A small passive internet of things practical development board with energy management function

Abstract

This invention relates to a small, passive IoT development board with energy management functionality. It comprises an IoT component, an energy management circuit, and an energy harvesting component. The energy harvested by the energy harvesting component powers the IoT component via the energy management circuit. Recognizing the current scarcity of practical passive IoT development boards, this invention integrates an energy management circuit with rectification, undervoltage lockout, adjustable threshold voltage, extremely low leakage current, and regulated output with a low-power SOC (System-on-Chip) minimum system capable of wireless networking communication such as Bluetooth, Wi-Fi, and Zigbee. This results in a compact, easily miniaturized, and mass-producible passive IoT development board. Users can adjust the energy management circuit and write specific Bluetooth communication commands according to their specific scenarios, thereby efficiently and reliably completing the entire passive IoT development process.

Description

Technical Field

[0001] This invention relates to a practical development board with energy management function for passive Internet of Things (IoT), belonging to the field of passive IoT. Background Technology

[0002] The Internet of Things (IoT) is booming. With the increasing number of IoT nodes, the cost of battery placement and maintenance within IoT devices will be extremely high. Therefore, with advancements in energy harvesting technology, passive IoT—a battery-free IoT—has emerged. Passive IoT can draw energy from solar energy, radio frequency signals, kinetic energy, and temperature differences, among others. Using dedicated energy harvesters, this energy can be collected to power IoT devices. However, the energy harvested from the environment is often intermittent, minute, and alternating current (AC), while IoT devices require stable direct current (DC). Therefore, passive energy cannot directly drive IoT devices, even in the lowest power SOC systems. This conversion requires an energy management circuit to store the harvested energy. Specifically, this is a comprehensive circuit that integrates rectification, undervoltage lockout, adjustable threshold voltage, extremely low leakage current, and regulated output. Currently, such comprehensive energy management modules are extremely scarce and expensive, hindering the development of passive IoT.

[0003] Among the numerous embedded development boards available, none are specifically designed for battery-free IoT scenarios, nor can any bridge the gap between micro-power management and upper-layer applications like IoT. In short, in the field of passive IoT, there is currently no practical development board that can simultaneously achieve energy management, adjustability, small size, low power consumption, and low cost. Summary of the Invention

[0004] The technical problem that this invention aims to solve is that in the field of passive Internet of Things (IoT), there is still no practical development board that can take into account energy management, adjustability, small size, low power consumption, and low cost.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is to provide a small passive IoT practical development board with energy management function, characterized in that it includes an IoT part, an energy management circuit, and an energy harvesting part, wherein the energy collected by the energy harvesting part powers the IoT part through the energy management circuit, wherein:

[0006] The Internet of Things (IoT) component is used to enable communication based on various mainstream networking methods;

[0007] The threshold voltage of the energy management circuit is adjustable. By adjusting the threshold voltage, micro-energy can be directly sent to the energy management circuit for energy storage without being boosted. Once the required voltage is reached, it is directly output at a regulated voltage. The energy management circuit consists of an energy input section, an energy storage section, an undervoltage lockout section, and a regulated output section. The energy collected by the energy harvesting section is input to the energy storage section through the energy input section. The energy storage section stores the energy and then powers the IoT component through the undervoltage lockout section and the regulated output section. The undervoltage lockout section determines whether the energy stored in the energy storage section meets the requirements. Only when the requirements are met is the energy stored in the energy storage section regulated by the regulated output section and then sent to the IoT component.

[0008] Preferably, the IoT component is implemented based on a low-power SOC minimum system, which is connected to a JLink interface and an antenna.

[0009] Preferably, the energy input section uses a diode to ensure unidirectional energy transfer; the energy storage section uses a capacitor; the undervoltage lockout section consists of an adjustable resistor, a transistor, and a field-effect transistor; and the regulated output section is implemented using a field-effect transistor.

[0010] Preferably, the energy management circuit includes an energy input section, and the energy input section is connected to capacitor C. s Parallel connection; the gate of power switch Q2 is connected to capacitor C via resistors R2 and R3 in series. s The positive terminal of the circuit is connected to the gate of power switch Q2 via resistor R1, while the gate of power switch Q2 is connected to capacitor C. s The negative terminal; the source terminal of power switch Q2 is connected to capacitor C. s The negative terminal of power switch Q2 is connected to one end of resistor R4, which in turn connects to the gate of power switch Q3. The other end of resistor R4 is connected to the input terminal of the current mirror, and the output terminal of the current mirror is connected to the gate of power switch Q2 via resistor R2. The source terminal of power switch Q3 is connected to capacitor C. s The positive terminal of the power switch Q3 is connected to the drain of the depletion-type NMOS Q4; the load R o It is connected between the gate and source of the depletion-type NMOS Q4.

[0011] This invention addresses the current scarcity of practical development boards in the passive IoT field. It integrates an energy management circuit with rectification, undervoltage lockout, adjustable threshold voltage, extremely low leakage current, and regulated output with a low-power SOC (System-on-Chip) minimum system capable of wireless networking communication via Bluetooth, Wi-Fi, and Zigbee. This results in a compact, easily miniaturized, and mass-producible practical passive IoT development board. Users can adjust the energy management circuitry and write specific Bluetooth communication commands according to their specific scenarios, thereby efficiently and reliably completing the entire passive IoT development process. Attached Figure Description

[0012] Figure 1A as well as Figure 1B This is a functional illustration diagram of the present invention. Figure 1A For the front, Figure 1B The opposite;

[0013] Figure 2 This is an energy flow diagram during normal operation of the present invention;

[0014] Figure 3 This is an energy flow diagram when the power supply of the present invention is stable;

[0015] Figure 4A and Figure 4B Line drawing illustrating an application example of the present invention. Figure 4A It's the front. Figure 4B It's the opposite;

[0016] Figure 5 This is a circuit diagram for the energy management of the present invention. Detailed Implementation

[0017] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0018] The IoT component of the development board provided by this invention consists of a low-power SOC minimum system, a JLink interface, and an antenna, enabling communication based on various mainstream networking methods. Its energy management circuit comprises diodes, capacitors, resistors, transistors, and MOSFETs, divided into four parts: energy input, energy storage, undervoltage lockout, and regulated output. Each part is designed to function with the fewest possible components, eliminating unnecessary parts. Therefore, the overall circuit is very compact, with extremely low energy consumption and cost, making widespread deployment of passive IoT possible.

[0019] Currently, commonly used passive IoT systems typically consist of the following components: energy harvesting equipment, boost circuitry, energy management circuitry, and IoT devices. Current energy harvesting and management circuits lack flexibility, exhibiting characteristics such as fixed thresholds and high power consumption. Such solutions are difficult to apply in large-scale production and consumer electronics scenarios. Compared to traditional energy management circuits, the energy management circuit of this invention (such as...) Figure 5 This invention is not only simpler and lower in cost, but also features an adjustable threshold voltage, enhanced programmability, and greater practicality. When powered by partial energy sources, such as magnetoelectric transducers, the collected voltage is only 2-3V, rendering the energy management circuit inoperable. Due to the flexible adjustability of the energy management circuit in this invention, a minimum threshold voltage setting of 1.8V can be achieved. This allows energy to be directly sent to the energy management circuit for storage without being boosted, and then directly stabilized for output once the required voltage is reached. This saves precious micro-energy, reduces energy dead zones, and significantly lowers the barrier to entry for passive IoT, making it possible to deploy IoT devices in batches for many small-energy-harvesting scenarios.

[0020] The collected energy is first rectified into DC by a rectifier, then stored in a capacitor. An undervoltage lockout circuit determines if the energy requirement is met. If the energy is insufficient, the low-power SOC will not be powered. If sufficient energy is detected, the energy will pass through a simplified voltage regulator circuit to activate the low-power SOC. The low-power SOC then transmits signals through an antenna, completing the entire passive IoT operation. Because the actual power of the signal transmitted by the low-power SOC can be calculated, the minimum threshold voltage that just meets the circuit's operating requirements can also be calculated, achieving a supply-demand balance.

[0021] like Figure 5 As shown, the energy management circuit provided by the present invention includes an energy input section, and the energy input section is connected to a capacitor C. s Parallel connection. The gate of power switch Q2 is connected to capacitor C via resistors R2 and R3 in series. s The positive terminal of the circuit is connected to the gate of power switch Q2 via resistor R1, while the gate of power switch Q2 is connected to capacitor C. s The negative terminal. The source of power switch Q2 is connected to capacitor C. s The negative terminal of power switch Q2 is connected to one end of resistor R4, which in turn connects to the gate of power switch Q3. The other end of resistor R4 is connected to the input of the current mirror, and the output of the current mirror is connected to the gate of power switch Q2 via resistor R2. The source of power switch Q3 is connected to capacitor C. s The positive terminal of the circuit is connected to the drain of the power switch Q3, which is connected to the drain of the depletion-type NMOS Q4. The load R... o It is connected between the gate and source of the depletion-type NMOS Q4. In this embodiment, a rectifier composed of four diodes serves as the energy input section. Capacitor C sIt provides energy storage. In the low-power wake-up circuit, the gate voltage of power switch Q2 increases with the increase of the storage voltage, during which power switch Q2 gradually turns on. The current of power switch Q2 is further mirrored to the gate of power switch Q2 by the current mirror composed of Q5, Q6, and R5, further increasing the voltage at the gate of power switch Q2. This forms a positive feedback, which strengthens the inversion of power switch Q2. At this time, the output of the common-source amplifier composed of power switch Q2 and resistor R4 is pulled low, turning on power switch Q3 and powering on the load. At the same time, resistor R3 is short-circuited by the current mirror, generating a voltage hysteresis window, forming an undervoltage lockout function. The load is powered on when the turn-on threshold voltage is reached, and turned off when the turn-off threshold voltage is lowered. The ratio of resistors R1 and R2 determines the turn-on and turn-off threshold voltages of the circuit, and the ratio of resistors R3 and R1 determines the width of the hysteresis window. Q4 is a depletion-mode NMOS, providing voltage regulation. When current flows through R... o When the load current is in the milliamp range, a relatively stable output voltage can be provided. This voltage regulation method has no additional quiescent current, thereby improving the survivability of IoT devices in low-power modes.

[0022] The entire development board is extremely small in size and equipped with GPIO ports for code debugging and programming. While providing convenient modification and debugging functions, it also meets the demands of IoT systems for small size and high efficiency. Both theory and practice have proven that this development board can operate stably in various energy harvesting applications, including piezoelectric, magnetoelectric, solar, radio frequency signals, and thermoelectric harvesting. It is particularly effective in the fields of micro-energy magnetoelectric and piezoelectric harvesting, contributing significantly to the development of passive IoT.

[0023] This invention is applicable to most passive IoT devices that harvest small amounts of energy. The micro-energy sources used include piezoelectric, magnetoelectric, and solar energy. As long as the resistance is adjusted so that the threshold voltage reaches the target value, this invention will work reliably in the application scenario.

[0024] When energy management is required, simply connect the ambient low-power supply to the development board's input. If energy management is not needed, the invention can be used directly as a miniature, low-power, reliable Bluetooth transceiver by connecting power to the VCC and GND ports of the JLink interface used for programming and debugging.

[0025] Figure 4A and Figure 4BThis illustration demonstrates an application example of the invention. In this example, the invention measures 2cm in length, 2cm in width, and 0.8cm in height. The front side represents the Internet of Things (IoT) component, employing the NRF52832 Bluetooth chip minimum system. The back side represents the energy management circuit of the invention. The power generation section utilizes an electromagnetic power generation device that converts pressure into electricity. Upon applying pressure, the AC micro-energy enters the energy management circuit. Since the energy cannot be directly supplied, it is first stored in a capacitor. Once an undervoltage lockout indicates sufficient energy, the energy is sent to the voltage regulator circuit to drive the NRF52832 chip to operate normally. The low-power code allows the acquired 0.8mJ of energy to drive the NRF52832 to send 5 iBeacon signal packets until the energy is depleted, at which point it enters a sleep state, waiting for sufficient energy to resume operation. If the collected energy is stable and exceeds the energy consumption of this low-power system, the NRF52832 will also continue to operate. This application example also includes a mobile app and an IoT platform mini-program for convenient debugging and direct application.

Claims

1. A small, passive IoT practical development board with energy management function, characterized in that, It includes an IoT component, an energy management circuit, and an energy harvesting component. The energy harvested by the energy harvesting component powers the IoT component through the energy management circuit. The Internet of Things (IoT) component is used to enable communication based on various mainstream networking methods; The threshold voltage of the energy management circuit is adjustable. By adjusting the threshold voltage, micro-energy can be directly sent to the energy management circuit for energy storage without being boosted. Once the required voltage is reached, it is directly regulated and output. The energy management circuit consists of an energy input section, an energy storage section, an undervoltage lockout section, and a regulated output section. The energy collected by the energy harvesting section is input to the energy storage section through the energy input section. The energy storage section stores the energy and supplies power to the IoT component through the undervoltage lockout section and the regulated output section. The undervoltage lockout section determines whether the energy stored in the energy storage section meets the requirements. Only when the requirements are met is the energy stored in the energy storage section regulated and output to the IoT component. The energy management circuit includes an energy input section, which is connected to capacitor C. s Parallel connection; the gate of power switch Q2 is connected to capacitor C via resistors R2 and R3 in series. s The positive terminal of the circuit is connected to the gate of power switch Q2 via resistor R1, while the gate of power switch Q2 is connected to capacitor C. s The negative terminal; the source terminal of power switch Q2 is connected to capacitor C. s The negative terminal of power switch Q2 is connected to one end of resistor R4, which in turn connects to the gate of power switch Q3. The other end of resistor R4 is connected to the input terminal of the current mirror, and the output terminal of the current mirror is connected to the gate of power switch Q2 via resistor R2. The source terminal of power switch Q3 is connected to capacitor C. s The positive terminal of the power switch Q3 is connected to the drain of the depletion-type NMOS Q4; the load R o It is connected between the gate and source of the depletion-type NMOS Q4.

2. The small passive IoT practical development board with energy management function as described in claim 1, characterized in that, The IoT component is implemented based on a low-power SOC minimum system, which is connected to a JLink interface and an antenna.

3. The small passive IoT practical development board with energy management function as described in claim 1, characterized in that, The energy input section uses diodes to ensure unidirectional energy transfer; the energy storage section uses capacitors; the undervoltage lockout section consists of an adjustable resistor, a transistor, and a field-effect transistor; and the regulated output section is implemented using a field-effect transistor.

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