A radio frequency self-powered gas detector and its control method

Abstract

The present invention provides a radio frequency self-powered gas detector and its control method. The detector includes a radio frequency energy harvester, a power microcontroller (PMIC), an energy storage element, a load switch 1, an MCU, a load switch 2, multiple MEMS gas sensors, an ink display, a lithium battery, a real-time clock (RTC), and a user reset button. By periodically controlling the gas sensor's power-on stabilization and data acquisition, as well as the microcontroller's sleep and wakeup functions, energy utilization is optimized. The gas detector requires no charging or additional battery placement; users simply place it next to a router, aim it at a mobile base station, or place it in other environments with sufficient wireless energy to enable autonomous operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless sensors, and in particular relates to a radio frequency self-powered gas detector and a control method thereof. Background Art

[0002] Radio frequency energy is a type of electromagnetic wave energy. It's primarily emitted by television base stations, mobile signal base stations, routers, and other sources. This RF energy provides a wireless transmission path for signals and also serves as a means of energy transmission. Most of this energy is dissipated into the air. Capturing and utilizing this energy could be of great value for energy conservation and emission reduction.

[0003] Existing gas detectors on the market (for formaldehyde, CO, CO2, O2, H2S, and air PM values) are all specialized, expensive, and mostly handheld devices that require frequent charging, making them unsuitable for general household use. With the development of the real estate and renovation industries, there has been a market gap in detecting toxic gases from furniture, flooring, and tiles. A small, low-cost, and extremely long-lasting (recharging-free) household gas detector is highly desirable. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a radio frequency self-powered gas detector and a control method thereof.

[0005] The present invention is achieved through the following technical solutions. The present invention proposes a radio frequency self-powered gas detector, which includes a radio frequency energy harvester, a PMIC, an energy storage element, a load switch 1, an MCU, a load switch 2, multiple MEMS gas sensors, an ink screen, a lithium battery, an RTC real-time clock, and a user reset button;

[0006] The RF energy harvester is connected to the PMIC, the PMIC is connected to the energy storage element and the load switch 1, the threshold management output pin PGOOD of the PMIC is connected to the enable pin EN1 of the load switch 1, and is used to control the on and off of the load switch 1; the output of the load switch 1 is connected to the MCU and the load switch 2, and the output of the load switch 2 is connected to multiple gas sensors and the ink screen; the MCU controls the on and off of the load switch 2 by outputting a high or low level connected to the EN2 pin of the load switch 2; the lithium battery is connected to the RTC real-time clock, which can supply the RTC real-time clock with a long working time; the RTC real-time clock communicates with the MCU via I2C, and the interrupt output of the RTC real-time clock is connected to the MCU; the user reset button is connected to the reset pin of the MCU.

[0007] The present invention also proposes a control method based on a radio frequency self-powered gas detector, which is specifically as follows:

[0008] S201: The RF energy harvester absorbs RF energy and outputs a DC voltage that is converted by the PMIC into energy storage capacitors for charging.

[0009] S202: The voltage of the energy storage capacitor reaches the high-voltage discharge threshold, load switch 1 is turned on to discharge, and the MCU and load switch 2 are powered;

[0010] S203: The MCU defines the variable flag = 1, controls the load switch 2 to be turned on, and the gas sensor and the ink display are powered and initialized;

[0011] S204: The MCU obtains the RTC real-time clock time, sets the RTC real-time clock alarm time to the time after T1, and then goes into sleep mode;

[0012] S205: The MCU is awakened by the alarm interrupt generated by the RTC real-time clock and collects gas sensor data after waking up;

[0013] S206: The MCU obtains the RTC real-time clock time and displays the obtained time and gas sensor data on the ink screen. Then, the RTC real-time clock alarm time is set to after T2 time, the variable flag value is set to 1, and then sleeps;

[0014] S207: The MCU is awakened by the alarm interrupt generated by the RTC real-time clock. After waking up, it is determined whether flag*T2>T3. If this condition is met, the process returns to S203 and executes again. If this condition is not met, the process executes S208.

[0015] S208: The MCU turns on load switch 2, the gas sensor and the ink screen are powered and initialized, and then the gas sensor data is read, and then the process returns to S206.

[0016] Furthermore, in the method, time T1 is the longest stabilization time required for all gas sensors, T3 is the shortest time that the data accuracy of all gas sensors can be maintained within a preset range, and T2 is the time interval designed by the manufacturer, that is, after the detector completes a power-on stabilization, data collection and display are performed once. Within the subsequent T3 time, gas data collection and display are performed once after the interval of T2 time, but power-on stabilization is no longer performed during this period, and gas data collection is performed directly. When the time length exceeds T3, it returns to the power-on stabilization working cycle.

[0017] Beneficial effects of the present invention:

[0018] The present invention proposes the first gas detector that is self-driven by ambient radio frequency energy. By periodically stabilizing the power supply of the gas sensor and controlling data acquisition, as well as waking up the microcontroller from sleep mode, it optimizes energy utilization. The gas detector does not require charging or additional batteries. Users only need to place it next to a router, aim it at a mobile base station, or place it in other environments with sufficient wireless energy, and it will work on its own. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A structural block diagram of a radio frequency self-powered gas detector provided by the present invention;

[0020] Figure 2 A schematic diagram of the working steps of a radio frequency self-powered gas detector provided by the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] In order to overcome the problems existing in the prior art, the present invention combines environmental radio frequency energy and gas detection technology to provide a gas detector that can absorb environmental radio frequency energy to power itself and realize environmental gas detection and display functions.

[0023] like Figure 1 As shown, Figure 1 The solid line represents energy flow, and the dotted line represents signal transmission. The present invention proposes a radio frequency self-powered gas detector, which includes a radio frequency energy harvester, a PMIC, an energy storage element, a load switch 1, an MCU, a load switch 2, multiple MEMS gas sensors, an ink display, a lithium battery, a real-time clock (RTC), and a user reset button.

[0024] The RF energy harvester is connected to the PMIC, the PMIC is connected to the energy storage element and the load switch 1, the threshold management output pin PGOOD of the PMIC is connected to the enable pin EN1 of the load switch 1, and is used to control the on and off of the load switch 1; the output of the load switch 1 is connected to the MCU and the load switch 2, and the output of the load switch 2 is connected to multiple gas sensors and an ink screen; the MCU controls the on and off of the load switch 2 by outputting a high or low level connected to the EN2 pin of the load switch 2; the lithium battery is connected to the RTC real-time clock, which can supply the RTC real-time clock with a long working time (generally more than 10 years); the RTC real-time clock communicates with the MCU via I2C, and the interrupt output of the RTC real-time clock is connected to the MCU; the user reset button is connected to the reset pin of the MCU.

[0025] The RF energy harvester collects RF energy, boosts it through the PMIC, and stores it in an energy storage element. When the stored charge reaches the discharge threshold, load switch 1 turns on, powering the MCU and load switch 2. The MCU controls the power supply of multiple gas sensors and the e-ink display by switching load switch 2 on and off. The energy storage element can be a storage capacitor or a rechargeable lithium battery, depending on the number of sensors and the power consumption per cycle.

[0026] The RF energy harvester, PMIC, energy storage element, and load switch 1 gradually accumulate weak RF energy. Before the energy storage element reaches the discharge threshold, PGOOD is low, the energy storage element continues to charge, and the voltage rises. When the energy storage element reaches the discharge threshold, PGOOD is high, load switch 1 turns on, and the energy storage element discharges. The energy storage element must have enough capacity to supply at least one load for power-up stabilization and data acquisition and display.

[0027] The RTC real-time clock is powered by a button lithium battery alone, has extremely low power consumption, and can theoretically operate for more than 10 years. The present invention is described with reference to Maxim's DS3231M real-time clock chip, which communicates with the MCU via I2C.

[0028] Combine Figure 2 The present invention also proposes a control method based on a radio frequency self-powered gas detector, the method specifically comprising:

[0029] S201: The RF energy harvester absorbs RF energy and outputs a DC voltage that is converted by the PMIC into energy storage capacitors for charging.

[0030] S202: The voltage of the energy storage capacitor reaches the high-voltage discharge threshold, load switch 1 is turned on to discharge, and the MCU and load switch 2 are powered;

[0031] S203: The MCU defines the variable flag = 1, controls the load switch 2 to be turned on, and the gas sensor and the ink display are powered and initialized;

[0032] S204: The MCU obtains the RTC real-time clock time, sets the RTC real-time clock alarm time to the time after T1, and then goes into sleep mode;

[0033] S205: The MCU is awakened by the alarm interrupt generated by the RTC real-time clock and collects gas sensor data after waking up;

[0034] S206: The MCU obtains the RTC real-time clock time and displays the obtained time and gas sensor data on the ink screen. Then, the RTC real-time clock alarm time is set to after T2 time, the variable flag value is set to 1, and then sleeps;

[0035] S207: The MCU is awakened by the alarm interrupt generated by the RTC real-time clock. After waking up, it is determined whether flag*T2>T3. If this condition is met, the process returns to S203 and executes again. If this condition is not met, the process executes S208.

[0036] S208: The MCU turns on load switch 2, the gas sensor and the ink screen are powered and initialized, and then the gas sensor data is read, and then the process returns to S206.

[0037] Most MEMS gas sensors have a power-on stabilization time, which is generally several minutes to several tens of minutes. After the power-on stabilization time, the measurement accuracy remains almost unchanged for several days (regardless of whether the power is turned on or off during this period). Therefore, in the present invention, a periodic power-on stabilization solution is adopted. The working steps of the gas detector are as follows: Figure 2 As shown, starting from S203, a flag is used to mark the number of gas collection and display operations. When the flag is 1, it is the initial collection, and collection must be performed after power-on stabilization. In the described method, time T1 is the longest stabilization time required for all gas sensors, T3 is the shortest time for all gas sensors to maintain data accuracy within a preset range, and T2 is the manufacturer's designated time interval. That is, after the detector completes a power-on stabilization, data collection and display are performed once. Within T3, gas data collection and display are performed again after an interval of T2, but power-on stabilization is not performed during this period. Instead, gas data collection is performed directly. When the time length exceeds T3, the power-on stabilization cycle is resumed. T1, T2, and T3 are set by the designer based on test results from multiple sensors. In step S207, the comparison between flag*T2 and T3 determines whether there were several gas data collections without power-on stabilization during two power-on stabilization cycles.

[0038] During the entire working process, the MCU communicates with the RTC real-time clock through I2C, obtains its time information, and sets the alarm interrupt.

[0039] The user reset button is connected to the MCU. When the user uses the gas detector for the first time, the user can press the reset button. After the user presses the reset button, the MCU will start a new working cycle to stabilize the gas sensor and measure in the area to be measured.

[0040] The E-ink display can maintain data for months or even longer after a power-off and data update. The collection time is displayed on the E-ink display each time data is collected, allowing users to easily check the date of the most recent measurement. For gas sensors, testing frequency does not need to be too frequent, so T2 can be set to 12 hours or longer to provide ample charging time for the gas detector.

[0041] When the gas detector is in an environment with a relatively weak wireless network for a long time, the energy in the energy storage element cannot be fully replenished. During the last acquisition and display work, the energy of the energy storage element is consumed to the low-voltage threshold of load switch 1, and load switch 1 is turned off, re-entering the next charging cycle.

[0042] The above is a detailed introduction to a radio frequency self-powered gas detector and a control method thereof proposed in the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A control method based on a radio frequency self-powered gas detector, characterized in that: The detector includes a radio frequency energy harvester, a PMIC, an energy storage element, a load switch 1, an MCU, a load switch 2, multiple MEMS gas sensors, an ink screen, a lithium battery, an RTC real-time clock, and a user reset button; The RF energy harvester is connected to the PMIC, which is connected to the energy storage element and load switch 1. The threshold management output pin PGOOD of the PMIC is connected to the enable pin EN1 of load switch 1 to control the on / off of load switch 1. The output of load switch 1 is connected to the MCU and load switch 2, and the output of load switch 2 is connected to multiple gas sensors and the ink screen. The MCU controls the on / off of load switch 2 by outputting a high or low level connected to the EN2 pin of load switch 2. The lithium battery is connected to the RTC real-time clock to provide long-term operation of the RTC real-time clock. The RTC real-time clock communicates with the MCU via I2C, and the RTC real-time clock interrupt output is connected to the MCU; the user reset button is connected to the MCU reset pin; The method is specifically as follows: S201: The RF energy harvester absorbs RF energy and outputs a DC voltage that is converted by the PMIC into energy storage capacitors for charging. S202: The voltage of the energy storage capacitor reaches the high-voltage discharge threshold, load switch 1 is turned on to discharge, and the MCU and load switch 2 are powered; S203: The MCU defines the variable flag = 1, controls the load switch 2 to be turned on, and the gas sensor and the ink display are powered and initialized; S204: The MCU obtains the RTC real-time clock time, sets the RTC real-time clock alarm time to the time after T1, and then goes into sleep mode; S205: The MCU is awakened by the alarm interrupt generated by the RTC real-time clock and collects gas sensor data after waking up; S206: The MCU obtains the RTC real-time clock time and displays the obtained time and gas sensor data on the ink screen. Then, the RTC real-time clock alarm time is set to after T2 time, the variable flag value is set to 1, and then sleeps; S207: The MCU is awakened by the alarm interrupt generated by the RTC real-time clock. After waking up, it is determined whether flag*T2>T3. If this condition is met, the process returns to S203 and executes again. If this condition is not met, the process executes S208. S208: The MCU turns on load switch 2, the gas sensor and the ink screen are powered and initialized, and then the gas sensor data is read, and then the process returns to S206.

2. The method according to claim 1, characterized in that In the method, time T1 is the longest stabilization time required for all gas sensors, T3 is the shortest time that the data accuracy of all gas sensors can be maintained within the preset range, and T2 is the time interval designed by the manufacturer. That is, after the detector completes a power-on stabilization, data collection and display are performed once. During the subsequent T3 time, gas data collection and display are performed once after the interval of T2, but power-on stabilization is no longer performed during this period, and gas data collection is performed directly. When the time length exceeds T3, the power-on stabilization working cycle is returned to.

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