CN214894985U - Device for measuring soil salinity - Google Patents
Device for measuring soil salinity Download PDFInfo
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- CN214894985U CN214894985U CN202120803539.6U CN202120803539U CN214894985U CN 214894985 U CN214894985 U CN 214894985U CN 202120803539 U CN202120803539 U CN 202120803539U CN 214894985 U CN214894985 U CN 214894985U
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Abstract
The utility model provides a device for measuring soil salinity, which comprises a probe, a square wave signal generating circuit, a signal collecting and processing circuit, a singlechip and an RS485 communication circuit; the square wave signal generating circuit generates square wave signals and sends the square wave signals to an excitation signal sending contact of the probe, the square wave signals periodically charge and discharge an equivalent capacitor formed by the probe and soil, the signal collecting and processing circuit collects and processes voltage changed on the equivalent capacitor and converts the voltage into a direct current voltage value, then analog voltage is obtained through sampling of an analog channel, and the single chip microcomputer converts the analog voltage value into digital value and calculates the corresponding salinity value. The utility model discloses after burying the probe in soil, can directly survey soil salinity, the stable performance, the sensitivity is high, and measuring range is wide, is suitable for the salinity survey of soil very much, and measures low cost, and the time is short, efficient.
Description
Technical Field
The utility model relates to a soil parameter measurement technical field, concretely relates to measure device of soil salinity.
Background
Proper salinity of soil is an important condition for plant growth, and the growth of crops is affected by excessive salinity or lack of salinity. The conductivity value of the soil is effectively obtained, and the method has great significance for determining the difference of various field parameters.
Currently, most of the prior art soil salinity measurement is laboratory measurement, and measurement is performed by using a corresponding instrument. Laboratory measurement of soil parameters has higher precision, but the measurement process is tedious, takes long time, and has high cost and poor real-time performance.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a measurement process to soil salinity is loaded down with trivial details, consuming time long, with high costs, the poor technical defect of real-time among the prior art, the utility model provides a measure device of soil salinity.
The utility model provides a device for measuring soil salinity, which comprises a probe, a square wave signal generating circuit, a signal collecting and processing circuit, a singlechip and an RS485 communication circuit;
the probe is provided with two contacts: an excitation signal transmitting contact and an electrical signal receiving contact;
the square wave signal generating circuit is used for generating square wave signals, and the output end of the square wave signal generating circuit is connected with the excitation signal sending contact;
the RS485 communication circuit is in communication connection with the single chip microcomputer so as to realize communication between the device for measuring soil salinity and external equipment;
the signal acquisition and processing circuit comprises an amplifying circuit, a blocking circuit, a shaping circuit, a voltage division output circuit, an analog channel circuit and a thermistor;
the input end of the amplifying circuit is connected with the electric signal receiving contact and is used for preliminarily amplifying the signals received by the electric signal receiving contact;
the input end of the blocking circuit is connected with the output end of the amplifying circuit and is used for blocking the signal after primary amplification;
the shaping circuit comprises a first operational amplifier, a first diode, a second diode, a first resistor, a second resistor, a third resistor and a zero setting circuit; one end of the first resistor is connected with the output end of the blocking circuit, and the other end of the first resistor is connected with the reverse input end of the first operational amplifier; the anode of the first diode is connected with the reverse input end of the first operational amplifier, the cathode of the first diode is connected with the output end of the first operational amplifier, the anode of the second diode is connected with the output end of the first operational amplifier, one end of the second resistor is connected with the reverse input end of the first operational amplifier, the other end of the second resistor is connected with one end of the third resistor, the other end of the third resistor is connected with the cathode of the second diode, two ends of the thermistor are connected between two ends of the second resistor in parallel, the output end of the zero-setting circuit is connected with the homodromous input end of the first operational amplifier, and the cathode of the second diode leads out the output end of the shaping circuit;
the input end of the voltage division output circuit is connected with the output end of the shaping circuit, and the voltage division output circuit divides the output signal of the shaping circuit and outputs the output signal to the analog channel circuit;
the input end of the analog channel circuit is connected with the output end of the voltage division output circuit so as to collect analog signals of signals output by the output end of the voltage division output circuit, and the output end of the analog channel circuit is connected to the AD input end of the single chip microcomputer.
Preferably, in the device for measuring soil salinity of the present invention, the amplifying circuit is an inverse proportion amplifying circuit.
Preferably, in the device for measuring soil salinity of the present invention, the zeroing circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and a slide rheostat; one end of the fourth resistor is connected with the positive power supply, the other end of the fourth resistor is connected with one end of the fifth resistor, the other end of the fifth resistor is grounded, one end of the sixth resistor is connected with the negative power supply, the other end of the sixth resistor is connected with one end of the seventh resistor, the other end of the seventh resistor is grounded, the sliding end of the sliding rheostat is connected to the same-direction input end of the first operational amplifier, and the other two ends of the sliding rheostat are respectively connected between one end of the fifth resistor and one end of the sixth resistor.
Preferably, the utility model discloses an among the device of measurement soil salinity, simulation channel circuit contains sampling resistor and filter capacitance, and bleeder output circuit's output is connected to sampling resistor's one end, and sampling resistor's the other end is connected shaping circuit's output, filter capacitance's one end is connected sampling resistor's the other end, filter capacitance's other end ground connection.
Preferably, in the device for measuring soil salinity of the present invention, the square wave signal generating circuit includes a rectangular wave generating circuit, a voltage dividing circuit, a voltage follower circuit, and a first LM4050-2.5 chip and a second LM4050-2.5 chip;
the output end of the rectangular wave generating circuit is connected with the 1 st pin of the first LM4050-2.5 chip, the 2 nd pin of the first LM4050-2.5 chip is connected with the 2 nd pin of the second LM4050-2.5 chip, and the 1 st pin of the second LM4050-2.5 chip is grounded;
the input end of the voltage division circuit is connected with the output end of the rectangular wave generation circuit;
the input end of the voltage follower circuit is connected with the output end of the voltage division circuit, and the input end of the voltage follower circuit is connected with the excitation signal sending contact.
Preferably, in the utility model discloses a measure device of soil salinity, the singlechip is STM8S003F3P6, the AD input is STM8S003F3P 6' S14 th pin.
Preferably, in the utility model discloses a measure device of soil salinity, the RS485 communication circuit includes chip SP3485, SP3485 'S1 st, 4 th pin is connected to STM8S003F3P 6' S3 rd, 2 nd, 3 rd pin of SP3485 is connected to STM8S003F3P6 'S10 th pin together, behind SP 3485' S6 th, 7 th pin each connect an output resistor, as RS485 communication circuit and outside connecting terminal, and SP3485 'S6 th pin connects 5V through pull-up resistance, SP 3485' S7 th pin through pull-down resistance ground connection.
Preferably, in the device for measuring soil salinity of the present invention, the output resistor has a size of 51 Ω, and the pull-down resistor and the pull-up resistor have a size of 47K Ω.
Preferably, IN the apparatus for measuring soil salt according to the present invention, the first diode and the second diode are IN 4148.
Preferably, in the device for measuring soil salinity of the present invention, the sampling resistor size is 4.7K Ω, and the filter capacitor is a 10 μ F capacitor and a 0.1uF capacitor connected in parallel.
Compared with the prior art, the utility model discloses after burying the probe in soil, can directly survey soil salinity, the stable performance, the sensitivity is high, and measuring range is wide, is suitable for the salinity survey of soil very much, and measures low cost, and the time is short, efficient.
Drawings
In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic diagram of a signal acquisition and processing circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a square wave signal generating circuit according to an embodiment of the present invention;
fig. 3 is the utility model discloses singlechip and RS485 communication circuit's of embodiment schematic diagram.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Referring to fig. 1-3, a device for measuring soil salinity includes a probe, a square wave signal generating circuit, a signal collecting and processing circuit, a single chip, and an RS485 communication circuit.
The probe (not shown) is provided with two graphite contacts: an excitation signal sending contact and an electric signal receiving contact, when the salt content is larger, the resistance between the two graphite contacts is smaller.
And the square wave signal generating circuit is used for generating square wave signals, and the output end of the square wave signal generating circuit is connected with the excitation signal sending contact.
Referring to fig. 2, the square wave signal generating circuit includes a rectangular wave generating circuit, a voltage dividing circuit, a voltage following circuit, and a first LM4050-2.5 chip and a second LM4050-2.5 chip;
the output end of the rectangular wave generating circuit is connected with the 1 st pin of the first LM4050-2.5 chip, the 2 nd pin of the first LM4050-2.5 chip is connected with the 2 nd pin of the second LM4050-2.5 chip, and the 1 st pin of the second LM4050-2.5 chip is grounded. The rectangular wave generating circuit comprises resistors R24, R29, R31 and R32, a capacitor C24 and an operational amplifier LM324, is a circuit which is common in the prior art, generates a 3.12V rectangular wave signal with a period of 820 mu s at a T1 position by self-oscillation of the rectangular wave signal and then passing through a first LM4050-2.5 chip and a second LM4050-2.5 chip.
The input end of the voltage division circuit is connected with the output end of the rectangular wave generation circuit, the voltage division circuit comprises a resistor R28 and a resistor R29, rectangular wave output with the period of 820 mu s and the voltage of about-30 mV to 30mV is generated at a T2 position after voltage division.
The input end of the voltage follower circuit is connected with the output end of the voltage division circuit, and the input end of the voltage follower circuit is connected with the excitation signal sending contact. The voltage follower circuit is realized by using an operational amplifier AMP _ LM324, and square wave output with the period of 820 mu s and the voltage of-40 mV to 40mV is generated at DJ1 and is output to the excitation signal sending contact.
Referring to fig. 1, the signal collecting and processing circuit includes an amplifying circuit, a blocking circuit, a shaping circuit, a voltage dividing output circuit, an analog channel circuit, and a thermistor.
And an input end DJ2 of the amplifying circuit is connected with the electric signal receiving contact and is used for preliminarily amplifying the signals received by the electric signal receiving contact. The amplifying circuit is an inverse proportion amplifying circuit and comprises an operational amplifier LM324(U6B) and a resistor R33, and the amplification factor of the amplifying circuit depends on the resistor R3 and the output resistor of the probe.
The input end of the blocking circuit is connected with the output end of the amplifying circuit and used for blocking the signal after primary amplification. The blocking circuit is realized by adopting a blocking capacitor, and specifically comprises: a capacitor C25 and a capacitor C26, both of which are 10 μ F in size.
The shaping circuit comprises a first operational amplifier U6C, a first diode D3, a second diode D4, a first resistor R34, a second resistor R38 and R39 (the two resistors are connected IN series to form a resistor), a third resistor R40 and R41 (the two resistors are connected IN series to form a resistor), and a zero setting circuit, wherein the first operational amplifier U6C also adopts LM324, and the first diode D3 and the second diode D4 adopt IN 4148. After the signal is processed by the shaping circuit, the output signal is a direct current signal.
One end of the first resistor R34 is connected with the output end of the blocking circuit, and the other end is connected with the reverse input end of the first operational amplifier U6C; the anode of the first diode D3 is connected with the inverting input terminal of the first operational amplifier, the cathode is connected with the output terminal of the first operational amplifier, the anode of the second diode D4 is connected with the output terminal of the first operational amplifier U6C, one ends of the second resistors R38 and R39 are connected with the inverting input terminal of the first operational amplifier U6C, the other ends of the second resistors R38 and R39 are connected with one ends of the third resistors R40 and R41, the other ends of the third resistors R40 and R41 are connected with the cathode of the second diode D4, two ends of a thermistor (not shown in the figure and connected between the 1 st pin and the 2 nd pin of the COM 1) are connected between two ends of the second resistors R38 and R39 in parallel, the output terminal of the zeroing circuit is connected with the equidirectional input terminal of the first operational amplifier U6C, and the cathode of the second diode D4 leads out the output terminal of the reshaping circuit.
The zero setting circuit comprises a fourth resistor R13, a fifth resistor R20, a sixth resistor R14, a seventh resistor R21 and a slide rheostat W1; one end of a fourth resistor R13 is connected with a positive power supply 5V, the other end of the fourth resistor R13 is connected with one end of a fifth resistor R20, the other end of the fifth resistor R20 is grounded, one end of a sixth resistor R14 is connected with a negative power supply-6V, the other end of the sixth resistor R14 is connected with one end of a seventh resistor R21, the other end of the seventh resistor R21 is grounded, a sliding end of the sliding rheostat W1 is connected with the same-direction input end of the first operational amplifier, and the other two ends of the sliding rheostat are respectively connected between one end of the fifth resistor R20 and one end of the sixth resistor R14. The sliding end of the sliding rheostat W1 outputs a zero-setting voltage VREF, and the output of the shaping circuit is adjusted through the zero-setting voltage VREF, so that the direct current bias is 0.
Thermistor response temperature variation, the temperature is higher, and the resistance is less to reduce shaping circuit's magnification, even make outside temperature change, the device of measuring soil salinity still can measure the salinity under a fixed temperature.
The input end of the voltage division output circuit is connected with the output end of the shaping circuit, and the voltage division output circuit divides the output signal of the shaping circuit and outputs the output signal to the analog channel circuit. The voltage division output circuit comprises a slide rheostat W2 and a resistor R36, after voltage division, the output is twice of the original output R36/(R36+ RW2), and RW2 is the effective resistance of the slide rheostat W2.
The input end of the analog channel circuit is connected with the output end of the voltage division output circuit so as to carry out analog signal acquisition on the signal output by the output end of the voltage division output circuit, and the output end of the analog channel circuit is connected to the AD input end of the single chip microcomputer. Preferably, in the utility model discloses a measure device of soil salinity, the singlechip is STM8S003F3P6, the AD input is STM8S003F3P 6' S14 th pin.
The analog channel circuit comprises a sampling resistor R26 and a filter capacitor, one end of the sampling resistor R26 is connected with the output end of the voltage division output circuit, the other end of the sampling resistor R26 is connected with the output end of the shaping circuit, one end of the filter capacitor is connected with the other end of the sampling resistor, and the other end of the filter capacitor is grounded. The size of the sampling resistor is 4.7K omega, and the capacitor C23 with the filtering capacitance of 10 mu F is connected with the capacitor C22 with the filtering capacitance of 0.1uF in parallel.
Referring to fig. 3, an RS485 communication circuit is in communication connection with the single chip microcomputer to realize communication between the device for measuring soil salinity and external equipment. The RS485 communication circuit comprises a chip SP3485, wherein the 1 st pin and the 4 th pin of the SP3485 are respectively connected to the 3 rd pin and the 2 nd pin of the STM8S003F3P6, the 2 nd pin and the 3 rd pin of the SP3485 are connected to the 10 th pin of the STM8S003F3P6, the 6 th pin and the 7 th pin of the SP3485 are respectively connected with an output resistor and then serve as connection terminals of the RS485 communication circuit and the outside, the 6 th pin of the SP3485 is connected with 5V through a pull-up resistor, and the 7 th pin of the SP3485 is grounded through a pull-down resistor. The output resistor is 51 omega, and the pull-down resistor and the pull-up resistor are both 47K omega.
The utility model discloses a theory of operation does: the square wave signal generating circuit generates square wave signals and sends the square wave signals to an excitation signal sending contact of the probe, the square wave signals periodically charge and discharge an equivalent capacitor formed by the probe and soil, the signal collecting and processing circuit collects and processes voltage changed on the equivalent capacitor and converts the voltage into a direct current voltage value, then analog voltage is obtained through sampling of an analog channel, and the single chip microcomputer converts the analog voltage value into digital value and calculates the corresponding salinity value.
The above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and not to limit the same; although the embodiments of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A device for measuring soil salinity is characterized by comprising a probe, a square wave signal generating circuit, a signal collecting and processing circuit, a single chip microcomputer and an RS485 communication circuit;
the probe is provided with two contacts: an excitation signal transmitting contact and an electrical signal receiving contact;
the square wave signal generating circuit is used for generating square wave signals, and the output end of the square wave signal generating circuit is connected with the excitation signal sending contact;
the RS485 communication circuit is in communication connection with the single chip microcomputer so as to realize communication between the device for measuring soil salinity and external equipment;
the signal acquisition and processing circuit comprises an amplifying circuit, a blocking circuit, a shaping circuit, a voltage division output circuit, an analog channel circuit and a thermistor;
the input end of the amplifying circuit is connected with the electric signal receiving contact and is used for preliminarily amplifying the signals received by the electric signal receiving contact;
the input end of the blocking circuit is connected with the output end of the amplifying circuit and is used for blocking the signal after primary amplification;
the shaping circuit comprises a first operational amplifier, a first diode, a second diode, a first resistor, a second resistor, a third resistor and a zero setting circuit; one end of the first resistor is connected with the output end of the blocking circuit, and the other end of the first resistor is connected with the reverse input end of the first operational amplifier; the anode of the first diode is connected with the reverse input end of the first operational amplifier, the cathode of the first diode is connected with the output end of the first operational amplifier, the anode of the second diode is connected with the output end of the first operational amplifier, one end of the second resistor is connected with the reverse input end of the first operational amplifier, the other end of the second resistor is connected with one end of the third resistor, the other end of the third resistor is connected with the cathode of the second diode, two ends of the thermistor are connected between two ends of the second resistor in parallel, the output end of the zero-setting circuit is connected with the homodromous input end of the first operational amplifier, and the cathode of the second diode leads out the output end of the shaping circuit;
the input end of the voltage division output circuit is connected with the output end of the shaping circuit, and the voltage division output circuit divides the output signal of the shaping circuit and outputs the output signal to the analog channel circuit;
the input end of the analog channel circuit is connected with the output end of the voltage division output circuit so as to collect analog signals of signals output by the output end of the voltage division output circuit, and the output end of the analog channel circuit is connected to the AD input end of the single chip microcomputer.
2. The apparatus of claim 1, wherein the amplification circuit is an inverse proportional amplification circuit.
3. The apparatus of claim 1, wherein the zeroing circuit comprises a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and a sliding resistor; one end of the fourth resistor is connected with the positive power supply, the other end of the fourth resistor is connected with one end of the fifth resistor, the other end of the fifth resistor is grounded, one end of the sixth resistor is connected with the negative power supply, the other end of the sixth resistor is connected with one end of the seventh resistor, the other end of the seventh resistor is grounded, the sliding end of the sliding rheostat is connected to the same-direction input end of the first operational amplifier, and the other two ends of the sliding rheostat are respectively connected between one end of the fifth resistor and one end of the sixth resistor.
4. The apparatus according to claim 1, wherein the analog channel circuit comprises a sampling resistor and a filter capacitor, one end of the sampling resistor is connected to the output terminal of the voltage dividing output circuit, the other end of the sampling resistor is connected to the output terminal of the shaping circuit, one end of the filter capacitor is connected to the other end of the sampling resistor, and the other end of the filter capacitor is grounded.
5. The apparatus of claim 1, wherein the square wave signal generating circuit comprises a rectangular wave generating circuit, a voltage dividing circuit, a voltage follower circuit, and a first LM4050-2.5 chip and a second LM4050-2.5 chip;
the output end of the rectangular wave generating circuit is connected with the 1 st pin of the first LM4050-2.5 chip, the 2 nd pin of the first LM4050-2.5 chip is connected with the 2 nd pin of the second LM4050-2.5 chip, and the 1 st pin of the second LM4050-2.5 chip is grounded;
the input end of the voltage division circuit is connected with the output end of the rectangular wave generation circuit;
the input end of the voltage follower circuit is connected with the output end of the voltage division circuit, and the input end of the voltage follower circuit is connected with the excitation signal sending contact.
6. The device of claim 1, wherein the single chip microcomputer is STM8S003F3P6, and the AD input is the 14 th pin of STM8S003F3P 6.
7. The device for measuring the soil salt content of claim 1, wherein the RS485 communication circuit comprises a chip SP3485, pins 1 and 4 of the SP3485 are respectively connected to pins 3 and 2 of an STM8S003F3P6, pins 2 and 3 of the SP3485 are connected together to pin 10 of an STM8S003F3P6, pins 6 and 7 of the SP3485 are respectively connected with an output resistor and then serve as connection terminals of the RS485 communication circuit and the outside, the pin 6 of the SP3485 is connected with 5V through a pull-up resistor, and the pin 7 of the SP3485 is connected with the ground through a pull-down resistor.
8. The apparatus of claim 7, wherein the output resistor has a size of 51 Ω, and the pull-down resistor and the pull-up resistor have a size of 47K Ω.
9. The apparatus of claim 1, wherein the first diode and the second diode are of the type IN 4148.
10. The apparatus of claim 4, wherein the sampling resistor has a size of 4.7K Ω, and the filter capacitor has a capacitance of 10 μ F and a capacitance of 0.1uF are connected in parallel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120803539.6U CN214894985U (en) | 2021-04-19 | 2021-04-19 | Device for measuring soil salinity |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120803539.6U CN214894985U (en) | 2021-04-19 | 2021-04-19 | Device for measuring soil salinity |
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| Publication Number | Publication Date |
|---|---|
| CN214894985U true CN214894985U (en) | 2021-11-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120803539.6U Active CN214894985U (en) | 2021-04-19 | 2021-04-19 | Device for measuring soil salinity |
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| CN (1) | CN214894985U (en) |
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2021
- 2021-04-19 CN CN202120803539.6U patent/CN214894985U/en active Active
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