CN110794003A - Multi-layered soil humidity sensor - Google Patents
Multi-layered soil humidity sensor Download PDFInfo
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- CN110794003A CN110794003A CN201911071582.1A CN201911071582A CN110794003A CN 110794003 A CN110794003 A CN 110794003A CN 201911071582 A CN201911071582 A CN 201911071582A CN 110794003 A CN110794003 A CN 110794003A
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- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/048—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance for determining moisture content of the material
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Abstract
The invention discloses a multi-layered soil humidity sensor, which comprises two parts of a probe and a circuit board, wherein one side of the probe is adhered with a plurality of groups of positive electrodes and negative electrodes which are formed by a plurality of groups of metal electrode plates which are parallel to each other, the metal electrode plates are connected with the circuit board through leads, the circuit of the circuit board comprises a booster circuit, a reference voltage circuit, 8 soil resistance acquisition and processing circuits with the same structure, an analog-digital conversion circuit and an analog-digital conversion control and output signal processing circuit, the probe transmits resistance signals in different layers in the acquired soil to the soil resistance acquisition and processing circuits, the resistance signals are subjected to operation and amplification by the circuits to obtain the soil humidity between the positive electrodes and the negative electrodes which are formed by the corresponding metal electrode plates on the probe, and the result is output to a PLC (programmable logic controller) or a display which is externally connected with the circuit board through U3 serial port P3.0 and, and (4) completing the calculation and display of the soil humidity of different layering positions in the soil.
Description
Technical Field
The invention relates to the technical field of sensing equipment, in particular to a multi-layered soil humidity sensor which is used for fine crop management.
Background
Currently, a soil humidity sensor used in an agricultural greenhouse is to insert two probes into soil to detect soil humidity, which is related to the conductivity of the soil contacted by the probes. In some refined crop management, it is desirable to detect continuous changes in soil moisture over a range of depths, i.e., to know the moisture at different soil depths in the soil into which the probe is inserted. Traditional soil moisture sensor can't once detect, need detect the different degree of depth that the probe inserted soil many times, and the operating personnel is difficult to the accurate depth of insertion who masters the probe in operation process, causes measured data inaccurate enough, can't satisfy the production needs.
Disclosure of Invention
The invention aims to provide a multi-layered soil humidity sensor to solve the problem that a conventionally used probe cannot detect the soil humidity value of soil within a depth range at one time.
In order to solve the problems, the technical scheme adopted by the invention is as follows:
a multi-layered soil humidity sensor comprises a probe and a circuit board, wherein the probe comprises two panels and a bottom plate which are made of insulating materials and have the same shape, the bottoms of the panels and the bottom plate are in an arrow shape, and the rear side of each panel is bonded with the front side of the bottom plate; one side of the panel is provided with 16 plug holes at uniform intervals along the length direction, the upper surface of each plug hole at the front side of the panel is adhered with a metal electrode plate horizontally arranged along the width direction of the panel, the 16 metal electrode plates are arranged in parallel, and the 16 metal electrode plates form 8 pairs of positive electrodes and 8 pairs of negative electrodes in pairs; 16 leads which are not mutually connected are welded on the front side of the bottom plate, the welding points of the leads correspond to the positions of the inserting holes one by one, when the panel is attached to the bottom plate, the welding points are inserted into the inserting holes, the welding points are abutted against the metal electrode plates, and the tail parts of the leads are led out from the top ends of the abutting surfaces of the panel and the bottom plate to be connected with the circuit board;
the circuit of the circuit board comprises a booster circuit, a reference voltage circuit, 8 soil resistance acquisition and processing circuits with the same structure, an analog-to-digital conversion circuit and an analog-to-digital conversion control and output signal processing circuit, wherein the input end of the booster circuit is connected with an external 5V power supply VCC, the output end of the booster circuit is connected with the reference voltage circuit, and the reference voltage circuit provides a stable reference power supply for the soil resistance acquisition and processing circuits and the analog-to-digital conversion circuit; the lead at the top end of the probe is connected with a soil resistance acquisition and processing circuit, the soil resistance acquisition and processing circuit is connected with an analog-to-digital conversion circuit, the analog-to-digital conversion circuit is connected with an analog-to-digital conversion control and output signal processing circuit, and the analog-to-digital conversion control and output signal processing circuit comprises a micro single chip microcomputer U3; the probe transmits resistance signals in different layers in the collected soil to the soil resistance collecting and processing circuit, after the collected resistance signals are subjected to voltage value operation and amplification by the soil resistance collecting and processing circuit, the analog voltage signal is transmitted to an analog-digital conversion circuit, the micro singlechip U3 controls the selection of the signal address in the analog-digital conversion circuit, the signal in the analog-digital conversion circuit is processed by the analog-digital conversion control and output signal processing circuit, and the soil resistance value between the positive electrode and the negative electrode which are formed by the corresponding metal electrode plates on the probe is obtained, the soil humidity is shown, the soil humidity result is output to a PLC (programmable logic controller) or other microcontrollers or computer signal acquisition boards which are externally connected with the circuit board through the serial port communication ports P3.0 and P3.1 of the micro single chip microcomputer U3, and the calculation and display of the soil humidity at different layering positions in the soil are completed.
Preferably, each soil resistance collecting and processing circuit comprises an integrated operational amplifier U1, the positive electrode input end of the integrated operational amplifier U1 is connected in series with a resistor R5 and then connected with the positive electrode formed by a corresponding metal electrode plate on the probe, the positive electrode formed by the metal electrode plate is connected in series with a voltage dividing resistor R4 and then connected with the V0 end of a three-terminal voltage-stabilized power supply module U4 in the reference voltage circuit, and the negative electrode input end of the integrated operational amplifier U1 is connected with the negative electrode formed by a corresponding metal electrode plate on the probe; a resistor R6 and a resistor R7 are connected in series between the negative electrode and the output end of the integrated operational amplifier U1, the resistor R5, the resistor R6 and the resistor R7 form an equidirectional proportional amplification circuit, and the voltage of the output end of the integrated operational amplifier U1 is equal to 2 times of the voltage of a positive electrode node formed by one metal electrode plate of the probe; the output end of the integrated operational amplifier U1 is connected with the signal input end I8 of the ADC chip U2 in the analog-to-digital conversion circuit.
Preferably, the analog-to-digital conversion circuit comprises an ADC chip U2, signal input terminals I8 of the ADC chip U2 are respectively connected to output terminals of 8 integrated amplifiers for analog-to-digital signal conversion, address lines and output terminals of the ADC chip U2 are both connected to a single chip microcomputer RP1, the single chip microcomputer RP1 controls selection of addresses by the ADC chip U2, and ADDA, ADDB, ADDC and ALE ports of the analog-to-digital conversion circuit are respectively connected to P2.0/A8, P2.1/a9, P2.2/a10 and P2.3/a11 ports of the analog-to-digital conversion control and output signal processing circuit.
Preferably, the boost circuit comprises a switching regulator U5, an inductor L1, a zener diode D1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a capacitor C3, wherein a Vi8 terminal of the switching regulator U5 is connected with an external 5v power source VCC and one terminal of the inductor L1, a SWITCH terminal of the switching regulator U5 is connected with the other terminal of the inductor L1 and the anode of the zener diode D1, the cathode of the zener diode D1 is connected with one terminal of the capacitor C3, the other terminal of the capacitor C3 is grounded, and the cathode of the zener diode D2 is an output terminal of the boost circuit, so as to output 12v voltage.
Preferably, the reference voltage circuit comprises a three-terminal stabilized voltage supply module U4, a VI terminal of the three-terminal stabilized voltage supply module U4 is connected with a cathode of a zener diode D2 and one end of a capacitor C8, the other end of the capacitor C8 is grounded, a V0 terminal of the three-terminal stabilized voltage supply module U4 is connected with one ends of a capacitor C7 and a resistor R9, and the other ends of a capacitor C7 and a resistor R9 are grounded; the V0 end of the three-end voltage-stabilized power supply module outputs stable 5V voltage to provide accurate reference voltage for the soil resistance acquisition and processing circuit and the analog-to-digital conversion circuit.
In the invention: the integrated operational amplifier U1 is LM324 in model, the ADC chip U2 is ADC0808 in model, the micro single chip microcomputer U3 is AT89C51 in model, the three-terminal voltage-stabilized power supply module U4 is 7805 in model, and the switching regulator U5 is LM2577-ADJ in model.
The working principle of the invention is as follows:
as shown by M1 in the soil resistance collecting and processing circuit in fig. 6, it includes an integrated operational amplifier U1 with model LM324, the positive input terminal 3+ of the integrated operational amplifier U1 is connected in series with the resistor R5 and then connected with the positive electrode P1+ formed by a corresponding metal electrode plate on the probe, the positive electrode P1+ formed by the metal electrode plate is connected in series with the voltage dividing resistor R4 and then connected with the V0 end of the three-terminal regulated power supply module U4 in the reference voltage circuit, and the negative input terminal 2-of the integrated operational amplifier U1 is connected with the negative electrode P1-formed by a corresponding metal electrode plate on the probe; a resistor R6 and a resistor R7 are connected in series between the negative electrode P1-and the output end of the integrated operational amplifier U1, the resistor R5, the resistor R6 and the resistor R7 form a homodromous proportional amplification circuit, and the voltage of the output end of the integrated operational amplifier U1 is equal to 2 times of the voltage of a positive electrode P1+ node formed by metal electrode plates of the probe; the output end of the integrated operational amplifier U1 is connected with the signal input end I8 of the ADC chip U2 in the analog-to-digital conversion circuit.
After the probe is inserted into soil, a resistor is equivalently connected between the two metal electrode plates, a voltage division circuit is formed by the resistor R4 and the resistor formed by the soil (the other end of the resistor R4 is connected to the V0 end of the three-terminal voltage-stabilized power supply module U4, so that a 5V reference voltage is input to the front end of the resistor R4), and the resistance value of the resistor R4 is approximately equal to the resistance value between the two metal electrode plates when the soil to be detected is completely dry. When the soil is completely hydrated, the positive electrode P1+ and the negative electrode P1-are short-circuited, and the voltage in front of the resistor R5 is 0V (the negative electrode P1-is grounded). The resistance between the positive electrode P1+ and the negative electrode P1-is equal to the resistance R4 when the soil is dry, and the voltage before the resistance R5 is 2.5 v. The voltage across resistor R5 will vary between 0 and 2.5v depending on the soil moisture.
Because the accurate measurement range of 2.5v is slightly too small, a homodromous proportional amplifying circuit consisting of an integrated operational amplifier U1, a resistor R5, a resistor R6 and a resistor R7 is introduced, and the voltage of the output end of the integrated operational amplifier U1 is equal to 2 times of the voltage of a positive electrode P1+ node consisting of a metal electrode slice; the voltage at the output of the integrated op amp U1 will vary from 0 to 5v as the soil moisture changes.
The probe is provided with 8 pairs of metal electrode plates, and 8 same soil resistance acquisition and processing circuit structures are arranged in the circuit; the other 7 soil resistance collecting and processing circuits in fig. 6 are respectively represented by M2, M3 to M8, Vp terminals in M2 to M8 are all connected to the output terminal (12v voltage) of the booster circuit, and out1 to out8 are output of 8 integrated operational amplifiers.
The booster circuit comprises a switching regulator U5, an inductor L1, a voltage stabilizing diode D1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a capacitor C3, and the switching regulator U5 is LM 2577-ADJ; the Vi8 end of the switching regulator U5 is connected with an external 5v power source VCC and one end of an inductor L1, the SWITCH end of the switching regulator U5 is connected with the other end of the inductor L1 and the anode of a voltage stabilizing diode D1, the cathode of the voltage stabilizing diode D1 is connected with one end of a capacitor C3, the other end of the capacitor C3 is grounded, and the cathode of the voltage stabilizing diode D2 is the output end of a boosting circuit to output 12v voltage.
The reference voltage circuit comprises a three-terminal voltage-stabilized power supply module U4, wherein the model of the three-terminal voltage-stabilized power supply module U4 is 7805; the VI end of the three-terminal stabilized power supply module U4 is connected with the cathode of a voltage stabilizing diode D2 and one end of a capacitor C8, the other end of the capacitor C8 is grounded, one ends of a capacitor C7 and a resistor R9 at the V0 end of the three-terminal stabilized power supply module U4 are connected, and the other ends of the capacitor C7 and the resistor R9 are grounded; the V0 end of the three-end voltage-stabilized power supply module outputs stable 5V voltage to provide accurate reference voltage for the soil resistance acquisition and processing circuit and the analog-to-digital conversion circuit.
The distance between two adjacent metal electrode plates is 8-12 mm. Can be set according to actual requirements.
The metal electrode plate is made of stainless steel conducting materials.
According to the invention, 16 mutually parallel metal electrode plates are continuously arranged on a probe, every two metal electrode plates form 8 pairs of positive electrodes and negative electrodes for measuring soil resistance, each metal electrode plate is connected with a lead, the lead is connected with a soil resistance collecting and processing circuit in a circuit board, and when the probe is inserted into soil, the resistance value of the finely layered soil in a depth range can be accurately collected; different hierarchical addresses are selected through the analog-to-digital conversion circuit and the single chip microcomputer RP1, and accurate data are provided for refined agricultural cultivation.
The circuit board adopts direct current 5v external power supply, can use general 5v power adapter as external power supply, convenient to use. The voltage fluctuation of the circuit is processed and stabilized through the booster circuit and the reference voltage stabilizing circuit, so that the influence of external voltage fluctuation is small; the invention has the advantages of low power consumption and high measurement precision, and can meet the requirement of fine cultivation management of crops.
Drawings
FIG. 1 is a view showing a state of use of a probe in the present invention;
FIG. 2 is a schematic structural view of the probe panel after a metal electrode sheet is adhered to the front side of the probe panel;
FIG. 3 is a schematic structural view of the probe panel before a metal electrode sheet is adhered to the front side of the probe panel;
FIG. 4 is a schematic diagram of the front side structure of the probe base plate;
FIG. 5 is a schematic illustration of the bonding of the probe face plate and backing plate;
FIG. 6 is a circuit schematic of the sensor;
in the figure: 1. the panel, 2, bottom plate, 3, metal electrode slice, 4, spliced eye, 5, wire, 6, welding point.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The multi-layered soil moisture sensor shown in fig. 1 to 5 comprises two parts, namely a probe and a circuit board, wherein the probe comprises a panel 1 and a bottom plate 2 which are made of insulating materials and have the same shape, the bottoms of the panel 1 and the bottom plate 2 are in an arrow shape, and the rear side of the panel 1 is bonded with the front side of the bottom plate 2; one side of the panel 1 is provided with 16 plug holes 4 at uniform intervals along the length direction, a metal electrode plate 3 horizontally arranged along the width direction of the panel 1 is stuck on the upper surface of each plug hole 4 at the front side of the panel 1, the 16 metal electrode plates 3 are arranged in parallel, and the 16 metal electrode plates 3 form 8 positive electrodes and 8 negative electrodes in pairs; 16 leads 5 which are not mutually connected are welded on the front side of the bottom plate 2, welding points 6 of the leads 5 correspond to the positions of the inserting holes 4 one by one, when the panel 1 is attached to the bottom plate 2, the welding points 6 are inserted into the inserting holes 4, the welding points 6 are abutted against the metal electrode plates 3, and the tail parts of the leads 5 are led out from the top ends of the abutting surfaces of the panel 1 and the bottom plate 2 to be connected with the circuit board;
the circuit of the circuit board shown in fig. 6 includes five parts, namely a booster circuit, a reference voltage circuit, 8 soil resistance acquisition and processing circuits with the same structure, an analog-to-digital conversion circuit and an analog-to-digital conversion control and output signal processing circuit, wherein the input end of the booster circuit is connected with an external 5V power source VCC, the output end of the booster circuit is connected with the reference voltage circuit, and the reference voltage circuit provides a stable reference power source for the soil resistance acquisition and processing circuit and the analog-to-digital conversion circuit; the lead 5 AT the top end of the probe is connected with a soil resistance collecting and processing circuit, the soil resistance collecting and processing circuit is connected with an analog-to-digital conversion circuit, the analog-to-digital conversion circuit is connected with an analog-to-digital conversion control and output signal processing circuit, the analog-to-digital conversion control and output signal processing circuit comprises a micro single chip microcomputer U3, and the micro single chip microcomputer U3 is AT89C51 in model number; the probe transmits resistance signals in different layers in the collected soil to the soil resistance collecting and processing circuit, after the collected resistance signals are subjected to voltage value operation and amplification by the soil resistance collecting and processing circuit, the analog voltage signal is transmitted to an analog-digital conversion circuit, the micro singlechip U3 controls the selection of the signal address in the analog-digital conversion circuit, the signal in the analog-digital conversion circuit is processed by the analog-digital conversion control and output signal processing circuit, and the soil resistance value between the positive electrode and the negative electrode which are formed by the corresponding metal electrode plates on the probe is obtained, the soil humidity is shown, the soil humidity result is output to a PLC (programmable logic controller) or other microcontrollers or computer signal acquisition boards which are externally connected with the circuit board through the serial port communication ports P3.0 and P3.1 of the micro single chip microcomputer U3, and the calculation and display of the soil humidity at different layering positions in the soil are completed.
The analog-to-digital conversion circuit comprises an ADC chip U2, the model of the ADC chip U2 is ADC0808, a signal input end I8 of the ADC chip U2 is respectively connected with output ends of 8 integrated operational amplifiers to convert analog-to-digital signals, an address line and an output end of the ADC chip U2 are both connected with a single chip microcomputer RP1, the single chip microcomputer RP1 controls the selection of the ADC chip U2 on addresses, and ADDA, ADDB, ADDC and ALE ports of the analog-to-digital conversion circuit are respectively connected with P2.0/A8, P2.1/A9, P2.2/A10 and P2.3/A11 ports of the analog-to-digital conversion control and output signal processing circuit.
As shown in M1 in the soil resistance collecting and processing circuit in fig. 6, it includes an integrated operational amplifier U1, the model of the integrated operational amplifier U1 is LM 324; the positive electrode input end 3+ of the integrated operational amplifier U1 is connected with a resistor R5 in series and then connected with a positive electrode P1+ formed by a corresponding metal electrode plate on the probe, a positive electrode P1+ formed by the metal electrode plate is connected with a voltage dividing resistor R4 in series and then connected with the V0 end of a three-terminal voltage-stabilized power supply module U4 in a reference voltage circuit, and the negative electrode input end 2-of the integrated operational amplifier U1 is connected with a negative electrode P1-formed by a corresponding metal electrode plate on the probe; a resistor R6 and a resistor R7 are connected in series between the negative electrode P1-and the output end of the integrated operational amplifier U1, the resistor R5, the resistor R6 and the resistor R7 form a homodromous proportional amplification circuit, and the voltage of the output end of the integrated operational amplifier U1 is equal to 2 times of the voltage of a positive electrode P1+ node formed by metal electrode plates of the probe; the output end of the integrated operational amplifier U1 is connected with the signal input end I8 of the ADC chip U2 in the analog-to-digital conversion circuit.
After the probe is inserted into soil, a resistor is equivalently connected between the two metal electrode plates, a voltage division circuit is formed by the resistor R4 and the resistor formed by the soil (the other end of the resistor R4 is connected to the V0 end of the three-terminal voltage-stabilized power supply module U4, so that a 5V reference voltage is input to the front end of the resistor R4), and the resistance value of the resistor R4 is approximately equal to the resistance value between the two metal electrode plates when the soil to be detected is completely dry. When the soil is completely hydrated, the positive electrode P1+ and the negative electrode P1-are short-circuited, and the voltage in front of the resistor R5 is 0V (the negative electrode P1-is grounded). The resistance between the positive electrode P1+ and the negative electrode P1-is equal to the resistance R4 when the soil is dry, and the voltage before the resistance R5 is 2.5 v. The voltage across resistor R5 will vary between 0 and 2.5v depending on the soil moisture.
Because the accurate measurement range of 2.5v is slightly too small, a homodromous proportional amplifying circuit consisting of an integrated operational amplifier U1, a resistor R5, a resistor R6 and a resistor R7 is introduced, and the voltage of the output end of the integrated operational amplifier U1 is equal to 2 times of the voltage of a positive electrode P1+ node consisting of a metal electrode slice; the voltage at the output of the integrated op amp U1 will vary from 0 to 5v as the soil moisture changes.
The probe is provided with 8 pairs of metal electrode plates, and 8 same soil resistance acquisition and processing circuit structures are arranged in the circuit; the other 7 soil resistance collecting and processing circuits in fig. 6 are respectively represented by M2, M3 to M8, Vp terminals in M2 to M8 are all connected to the output terminal (12v voltage) of the booster circuit, and out1 to out8 are output of 8 integrated operational amplifiers.
The booster circuit comprises a switching regulator U5, an inductor L1, a voltage stabilizing diode D1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a capacitor C3, and the switching regulator U5 is LM 2577-ADJ; the Vi8 end of the switching regulator U5 is connected with an external 5v power source VCC and one end of an inductor L1, the SWITCH end of the switching regulator U5 is connected with the other end of the inductor L1 and the anode of a voltage stabilizing diode D1, the cathode of the voltage stabilizing diode D1 is connected with one end of a capacitor C3, the other end of the capacitor C3 is grounded, and the cathode of the voltage stabilizing diode D2 is the output end of a boosting circuit to output 12v voltage.
The reference voltage circuit comprises a three-terminal voltage-stabilized power supply module U4, wherein the model of the three-terminal voltage-stabilized power supply module U4 is 7805; the VI end of the three-terminal stabilized power supply module U4 is connected with the cathode of a voltage stabilizing diode D2 and one end of a capacitor C8, the other end of the capacitor C8 is grounded, one ends of a capacitor C7 and a resistor R9 at the V0 end of the three-terminal stabilized power supply module U4 are connected, and the other ends of the capacitor C7 and the resistor R9 are grounded; the V0 end of the three-end voltage-stabilized power supply module outputs stable 5V voltage to provide accurate reference voltage for the soil resistance acquisition and processing circuit and the analog-to-digital conversion circuit.
The distance between two adjacent metal electrode plates 3 is 8-12 mm. The metal electrode plate 3 is made of stainless steel conductive material.
When the invention is used, the analog-to-digital conversion control and output signal processing circuit controls the analog-to-digital conversion circuit and processes the final conversion model, such as: when the ports ADDC, ADDB and ADDA of the ADC chip U2 are 001 respectively and the voltage output signal of the first integrated operational amplifier U1 is 5v, the invention converts the partial pressure of the soil resistance between the positive electrode P1+ and the negative electrode P1-into a digital signal, the P2.4 port of the micro singlechip U3 is connected with the CLOCK end of the ADC chip U2, the micro singlechip U3 provides a CLOCK signal required by the work for the ADC chip U2, and the CLOCK signal is set to be 100 Hz. The P2.3 port of the micro-singlechip U3 is connected with the ALE port and the START port of the ADC chip U2, and when a square wave signal (with the duty ratio of 1/2) of 50Hz (related to the CLOCK CLOCK signal) is generated at the P2.3 port, corresponding binary digital signals 11111111111111 are generated at the OUT1 to OUT8 ports of the ADC chip U2; when the voltage output signal of the first integrated op amp U1 is 5v when the ADDC, ADDB, and ADDA ports of the ADC chip U2 are 001, respectively, the OUT1 to OUT8 ports of the ADC chip U2 generate the corresponding binary digital signal 10101010.
(10101010)2/(11111111)2*5＝3.3
In the above equation, 5 represents a reference voltage 5 v.
The above formula illustrates: the P0 port of the micro singlechip U3 receives the digital signal output by the ADC chip U2, the output digital signal is divided by (11111111)2 and then multiplied by the reference voltage 5v, so that the soil resistance value between corresponding metal electrode plates on the probe can be obtained, and the soil humidity is reflected; when this value is 5, the soil is completely dry; when this value is 0, the soil is close to a conductor; the result of the soil humidity is output to a PLC industrial controller or a display connected with the outside of the circuit board through serial port communication ports P3.0 and P3.1 of the micro single chip microcomputer U3, and the calculation and display of the soil humidity of different layering positions in the soil are completed.
Claims (7)
1. The utility model provides a many layering soil moisture sensor, it includes probe and circuit board two parts, its characterized in that: the probe comprises a panel (1) and a bottom plate (2) which are made of insulating materials and have the same shape, the bottoms of the panel (1) and the bottom plate (2) are in an arrow shape, and the rear side of the panel (1) is bonded with the front side of the bottom plate (2); 16 plug holes (4) are uniformly arranged at intervals along the length direction of one side of the panel (1), a metal electrode plate (3) horizontally arranged along the width direction of the panel (1) is stuck on the upper surface of each plug hole (4) at the front side of the panel (1), the 16 metal electrode plates (3) are arranged in parallel, and the 16 metal electrode plates (3) form 8 alignment electrodes and 8 negative electrodes in pairs; 16 leads (5) which are not mutually jointed are welded on the front side of the bottom plate (2), welding points (6) of the leads (5) correspond to the positions of the inserting holes (4) one by one, when the panel (1) is attached to the bottom plate (2), the welding points (6) are inserted into the inserting holes (4), the welding points (6) are abutted against the metal electrode plates (3), and the tail parts of the leads (5) are led out from the top ends of the butt joint surfaces of the panel (1) and the bottom plate (2) to be connected with a circuit board;
the circuit of the circuit board comprises a booster circuit, a reference voltage circuit, 8 soil resistance acquisition and processing circuits with the same structure, an analog-to-digital conversion circuit and an analog-to-digital conversion control and output signal processing circuit, wherein the input end of the booster circuit is connected with an external 5V power supply VCC, the output end of the booster circuit is connected with the reference voltage circuit, and the reference voltage circuit provides a stable reference power supply for the soil resistance acquisition and processing circuits and the analog-to-digital conversion circuit; the lead at the top end of the probe is connected with a soil resistance acquisition and processing circuit, the soil resistance acquisition and processing circuit is connected with an analog-to-digital conversion circuit, the analog-to-digital conversion circuit is connected with an analog-to-digital conversion control and output signal processing circuit, and the analog-to-digital conversion control and output signal processing circuit comprises a micro single chip microcomputer U3; the probe transmits resistance signals in different layers in the collected soil to the soil resistance collecting and processing circuit, after the collected resistance signals are subjected to voltage value operation and amplification by the soil resistance collecting and processing circuit, the analog voltage signal is transmitted to an analog-digital conversion circuit, the micro singlechip U3 controls the selection of the signal address in the analog-digital conversion circuit, the signal in the analog-digital conversion circuit is processed by the analog-digital conversion control and output signal processing circuit, and the soil resistance value between the positive electrode and the negative electrode which are formed by the corresponding metal electrode plates on the probe is obtained, the soil humidity is shown, the soil humidity result is output to a PLC (programmable logic controller) or other microcontrollers or computer signal acquisition boards which are externally connected with the circuit board through the serial port communication ports P3.0 and P3.1 of the micro single chip microcomputer U3, and the calculation and display of the soil humidity at different layering positions in the soil are completed.
2. The multi-layered soil moisture sensor of claim 1, wherein: each soil resistance collecting and processing circuit comprises an integrated operational amplifier U1, the positive electrode input end of the integrated operational amplifier U1 is connected with the positive electrode formed by a corresponding metal electrode plate on the probe after being connected with a resistor R5 in series, the positive electrode formed by the metal electrode plate is connected with the V0 end of a three-terminal voltage-stabilized power supply module U4 in the reference voltage circuit after being connected with a voltage dividing resistor R4 in series, and the negative electrode input end of the integrated operational amplifier U1 is connected with the negative electrode formed by a corresponding metal electrode plate on the probe; a resistor R6 and a resistor R7 are connected in series between the negative electrode and the output end of the integrated operational amplifier U1, the resistor R5, the resistor R6 and the resistor R7 form an equidirectional proportional amplification circuit, and the voltage of the output end of the integrated operational amplifier U1 is equal to 2 times of the voltage of a positive electrode node formed by one metal electrode plate of the probe; the output end of the integrated operational amplifier U1 is connected with the signal input end I8 of the ADC chip U2 in the analog-to-digital conversion circuit.
3. The multi-layered soil moisture sensor of claim 1 or 2, wherein: the analog-to-digital conversion circuit comprises an ADC chip U2, a signal input end I8 of the ADC chip U2 is respectively connected with output ends of 8 integrated operational amplifiers to convert analog-to-digital signals, an address line and an output end of the ADC chip U2 are connected with a single chip microcomputer RP1, the single chip microcomputer RP1 controls selection of an address by the ADC chip U2, and ADDA, ADDB, ADDC and ALE ports of the analog-to-digital conversion circuit are respectively connected with P2.0/A8, P2.1/A9, P2.2/A10 and P2.3/A11 ports of the analog-to-digital conversion control and output signal processing circuit.
4. The multi-layered soil moisture sensor of claim 3, wherein: the boost circuit comprises a switching regulator U5, an inductor L1, a voltage stabilizing diode D1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1, a capacitor C2 and a capacitor C3, wherein a Vi8 end of a switching regulator U5 is connected with an external 5v power supply VCC and one end of the inductor L1, a SWITCH end of the switching regulator U5 is connected with the other end of the inductor L1 and the anode of the voltage stabilizing diode D1, the cathode of the voltage stabilizing diode D1 is connected with one end of the capacitor C3, the other end of the capacitor C3 is grounded, the cathode of the voltage stabilizing diode D2 is the output end of the boost circuit, and 12v voltage is output.
5. The multi-layered soil moisture sensor of claim 4, wherein: the reference voltage circuit comprises a three-terminal stabilized voltage supply module U4, wherein the VI end of the three-terminal stabilized voltage supply module U4 is connected with the cathode of a voltage stabilizing diode D2 and one end of a capacitor C8, the other end of the capacitor C8 is grounded, one ends of a capacitor C7 and a resistor R9 at the V0 end of the three-terminal stabilized voltage supply module U4 are connected, and the other ends of the capacitor C7 and the resistor R9 are grounded; the V0 end of the three-end voltage-stabilized power supply module outputs stable 5V voltage to provide accurate reference voltage for the soil resistance acquisition and processing circuit and the analog-to-digital conversion circuit.
6. The multi-layered soil moisture sensor of claim 4, wherein: the distance between two adjacent metal electrode plates (3) is 8-12 mm.
7. The multi-layered soil moisture sensor of claim 6, wherein: the metal electrode plate (3) is made of a stainless steel conductive material.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111458380A (en) * | 2020-03-03 | 2020-07-28 | 陈金丽 | Rainfall infiltration groundwater supply measuring device and analysis algorithm for rapid field deployment |
| CN111458484A (en) * | 2020-05-28 | 2020-07-28 | 邯郸市耘农智慧农业科技有限公司 | Wisdom agricultural is with small-size soil temperature and humidity salt sensor |
| CN112285398A (en) * | 2020-10-11 | 2021-01-29 | 浙江晨泰科技股份有限公司 | Electric energy meter capable of detecting humidity abnormity |
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2019
- 2019-11-05 CN CN201911071582.1A patent/CN110794003A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111458380A (en) * | 2020-03-03 | 2020-07-28 | 陈金丽 | Rainfall infiltration groundwater supply measuring device and analysis algorithm for rapid field deployment |
| CN111458484A (en) * | 2020-05-28 | 2020-07-28 | 邯郸市耘农智慧农业科技有限公司 | Wisdom agricultural is with small-size soil temperature and humidity salt sensor |
| CN112285398A (en) * | 2020-10-11 | 2021-01-29 | 浙江晨泰科技股份有限公司 | Electric energy meter capable of detecting humidity abnormity |
| CN112285398B (en) * | 2020-10-11 | 2023-08-08 | 浙江晨泰科技股份有限公司 | Electric energy meter capable of detecting humidity abnormality |
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