Circuit and method for simulating different resistive pressure sensors to generate calibration coefficients

Abstract

The invention provides a circuit and method for simulating different resistive pressure sensors to generate calibration coefficients. The circuit comprises a bridge voltage generation circuit, a multi-path analog switch, a microcontroller and a conditioning conversion circuit. The bridge voltage generation circuit comprises a first common-mode voltage resistor, at least two divider resistors and a second common-mode voltage resistor which are connected in series, and the resistors connected in series serve as divider nodes; a plurality of input and output selection ports of the multi-path analog switch are connected with different voltage division nodes, a public input and output port of the multi-path analog switch is connected with a VIN port of the conditioning conversion circuit, and a microcontroller is adopted to control the state of an address selection port so as to realize a voltage division node gating mode; and a VIP port of the conditioning conversion circuit is connected with a zero voltage division node of the bridge voltage generation circuit. The technical problems that in the prior art, when a conditioning conversion circuit board generates the calibration coefficient, the conditioning conversion circuit board needs to be matched with the pressure sensors one by one, operation is tedious, batch automation is not suitable to be achieved, and the pressure sensors are prone to being damaged manually can be solved.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a circuit and method for simulating different resistance pressure sensors to generate calibration coefficients. Background Art

[0002] Water level monitoring is one of the most important parameters for geothermal remote dynamic monitoring. Resistive pressure sensors are often used to convert water pressure into voltage signals, and then the voltage signals are converted into 4-20mA current signals or RS485 digital signals through conditioning and conversion circuit boards, which are then transmitted to the remote terminal on the well for collection through long cables. The conditioning and conversion circuit needs to be connected to the resistive pressure sensor first, and the calibration software provided is used to obtain at least 2 (usually zero point, full scale) or 3 (usually zero point, middle point, full scale) or more pressure data points of the resistive pressure sensor (input through the air pressure calibration device) for curve fitting, and the calibration coefficient of the conditioning and conversion circuit is obtained, and the calibration coefficient is configured in the conditioning and conversion circuit. At this point, the conditioning and conversion circuit has the function of real-time conditioning and conversion, otherwise it is like a single-chip microcomputer without a burning program and does not work.

[0003] Due to the differences in zero points and full scales of different resistive pressure sensors, most of the current methods use a method that pairs the resistive pressure sensor with a conditioning conversion circuit, manually inputs different air pressure values, and collects and fits to generate calibration coefficients. This method is not easy to achieve in batches, has poor interchangeability, and the pressure sensor, as a relatively expensive core, is involved in the debugging stage, which may cause damage to the expensive pressure sensor core due to improper manual operation. Summary of the invention

[0004] The present invention aims to solve the technical problems that the conditioning conversion circuit board needs to be paired with the pressure sensor one by one when performing coefficient calibration and generation, which leads to the cumbersome operation process, the difficulty in realizing batch automation, and the easy occurrence of man-made damage to the pressure sensor. The present invention provides a circuit and method for simulating different resistive pressure sensors to generate calibration coefficients. By simulating the bridge circuit of a real resistive pressure sensor, the switching setting of zero position, full scale and intermediate value is automatically performed, and the generation of the standard coefficient of the conditioning conversion circuit board is automatically completed. The method can quickly realize the automation of calibration coefficient configuration, effectively improve production efficiency, and reduce man-made damage.

[0005] The present invention provides a circuit for simulating different resistance pressure sensors to generate calibration coefficients, including a bridge voltage generating circuit, a multi-channel analog switch, a microcontroller, and a conditioning conversion circuit;

[0006] The bridge voltage generating circuit comprises a first common-mode voltage resistor, at least two voltage-dividing resistors, and a second common-mode voltage resistor connected in series in sequence, wherein one end of the first common-mode voltage resistor away from the voltage-dividing resistor is connected to a reference voltage of a conditioning and conversion circuit, one end of the second common-mode voltage resistor away from the voltage-dividing resistor is grounded, and the first common-mode voltage resistor, the second common-mode voltage resistor and adjacent voltage-dividing resistors, and the adjacent voltage-dividing resistors are used as voltage-dividing nodes;

[0007] The multi-way analog switch includes an input / output selection port, an address selection port, and a common input / output port; the input / output selection ports are at least three and connected to different voltage-dividing nodes of the voltage-dividing resistor of the bridge circuit; the common input / output port is connected to the VIN port of the conditioning conversion circuit; the address selection ports are at least two, and the state of the address selection ports is controlled by a microcontroller to realize the control of the gating mode of the input / output selection ports;

[0008] The VIP port of the conditioning and conversion circuit is connected to the zero-position voltage dividing node of the bridge voltage generating circuit.

[0009] Furthermore, the voltage-dividing resistors connected in series are respectively connected in parallel with the first and second fine-tuning resistors, and a single-way switch is respectively provided on the parallel branches of the first and second fine-tuning resistors.

[0010] Furthermore, the resistance values ​​of the first and second fine-tuning resistors are integer multiples of the sum of a plurality of voltage-dividing resistors.

[0011] Furthermore, the resistance values ​​of the voltage-dividing resistors are the same, and the resistance values ​​of the first common-mode voltage resistor and the second common-mode voltage resistor are the same.

[0012] Furthermore, the multi-way analog switch also includes

[0013] The positive terminal is connected to the power supply and connected to the ground through a capacitor;

[0014] Two negative terminals, connected to the ground;

[0015] Low level enable port, connected to ground.

[0016] Furthermore, the microcontroller also includes a voltage acquisition port, which is connected to a voltage dividing node between the voltage dividing resistors of the bridge voltage generating circuit, and is used to monitor the current value of the bridge voltage generating circuit by acquiring the voltage of the voltage dividing node.

[0017] The present invention also provides a method for simulating different resistance pressure sensors to generate calibration coefficients. Using the above circuit, the method for generating calibration coefficients includes the following steps:

[0018] Count the minimum zero voltage value and the full-scale voltage value of a batch of resistive pressure sensors in the actual use range;

[0019] Determine the difference between the positive and negative pressure inputs of the conditioning conversion circuit with the full-scale voltage value, set the number and resistance value of the voltage divider resistors, and calculate the maximum current value of the bridge voltage generating circuit;

[0020] Calculate the common mode voltage resistance value based on the reference voltage value of the conditioning conversion circuit and the maximum current value of the bridge voltage generating circuit;

[0021] Analyze the voltage difference of each voltage division node, and determine the zero voltage voltage division node and the full-scale voltage voltage division node among the voltage division nodes;

[0022] The voltage-dividing node of the bridge voltage generating circuit is selected by a multi-way analog switch, and the output of the resistive pressure sensor is simulated by using the zero-position voltage, the full-scale voltage and the intermediate voltage therebetween, and the input is input into the conditioning conversion circuit. The calibration coefficient of the conditioning conversion circuit is generated by the least squares fitting method, and the calibration coefficient is configured in the conditioning conversion circuit.

[0023] Furthermore, the method also includes using a microcontroller to monitor the voltage of an intermediate voltage-dividing node of the bridge voltage generating circuit. When the voltage does not meet the requirements, a fine-tuning resistor is introduced to adjust the resistance value or number of parallel fine-tuning resistors so that the voltage of the intermediate voltage-dividing node meets the requirements.

[0024] Furthermore, it also includes the step of calculating the output current of the conditioning conversion circuit corresponding to each voltage-dividing node of the bridge voltage generating circuit when it is selected, and verifying the accuracy of the generated calibration coefficient.

[0025] Beneficial effects of the present invention:

[0026] The present invention provides a circuit and method for simulating different resistive pressure sensors to generate calibration coefficients. The circuit controls the selection of multi-channel analog switch channels through a microcontroller, automatically adjusts the zero voltage, intermediate value voltage, full-scale voltage and other voltage values ​​of the bridge voltage generating circuit, and then adjusts the pressure difference value output by the bridge voltage generating circuit to the conditioning conversion circuit. The conditioning conversion circuit then generates the calibration coefficient by fitting the different pressure difference values ​​collected through the least squares method. The circuit can fully automatically perform the switching settings of the zero position, full scale and intermediate value, and does not need to input the air pressure signal through the air pressure calibration device. It can automatically complete the setting of the zero position, relay value and full scale according to the resistive pressure sensors of different ranges, effectively improving production efficiency and reducing human damage.

[0027] The present invention sets a fine-tuning resistor in the bridge voltage generating circuit to fine-tune the voltage difference between VIP and VIN. The voltage difference control accuracy is increased by designing the voltage divider resistor and the common mode voltage resistor parameters of the bridge voltage generating circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of the structure of a multi-channel analog switch circuit provided according to a specific embodiment of the present invention is shown;

[0030] Figure 2 A schematic structural diagram of a bridge voltage generating circuit provided according to a specific embodiment of the present invention is shown;

[0031] Figure 3 A schematic structural diagram of a single-way switch circuit provided according to a specific embodiment of the present invention is shown;

[0032] Figure 4 A schematic diagram of the structure of a microcontroller control circuit provided according to a specific embodiment of the present invention is shown;

[0033] Figure 5 A structural schematic diagram of a conditioning conversion circuit provided according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0037] As a specific embodiment of the present invention, a circuit for simulating different resistive pressure sensors to generate calibration coefficients is provided, including a bridge voltage generating circuit, a multi-way analog switch, a microcontroller, and a conditioning conversion circuit. Specifically:

[0038] The bridge voltage generating circuit comprises a first common-mode voltage resistor, at least two voltage-dividing resistors, and a second common-mode voltage resistor which are connected in series in sequence, wherein one end of the first common-mode voltage resistor away from the voltage-dividing resistor is connected to a reference voltage VREF of a conditioning and conversion circuit, one end of the second common-mode voltage resistor away from the voltage-dividing resistor is grounded, and the first common-mode voltage resistor, the second common-mode voltage resistor and adjacent voltage-dividing resistors, and the adjacent voltage-dividing resistors are used as voltage-dividing nodes;

[0039] The multi-channel analog switch includes an input / output selection port, an address selection port, and a common input / output port. There are at least three input / output selection ports connected to different voltage-dividing nodes of the voltage-dividing resistors of the bridge circuit. The common input / output port is connected to the negative voltage input VIN port of the conditioning conversion circuit. There are at least two address selection ports, including two states of 0 and 1. The state of the address selection port is controlled by a microcontroller to control the gating mode of the input / output selection port.

[0040] The positive voltage input VIP port of the conditioning conversion circuit is connected to the zero-position voltage-dividing node of the bridge voltage generating circuit.

[0041] The circuit for simulating different resistive pressure sensors to generate calibration coefficients provided by the present invention adopts a bridge voltage generating circuit to generate zero voltage, intermediate value voltage, and full-scale voltage, and controls the selection of multi-channel analog switch channels through a microcontroller, thereby controlling the pressure difference value output by the bridge voltage generating circuit to the conditioning conversion circuit, so as to facilitate the rapid generation of calibration coefficients. The circuit can fully automatically perform the switching settings of zero position, full scale, and intermediate value, and does not need to input the air pressure signal through the air pressure calibration device, and can automatically complete the setting of zero position, intermediate value, and full scale according to the resistive pressure sensors of different ranges, effectively improving production efficiency and reducing human damage.

[0042] Furthermore, the two ends of multiple series voltage-dividing resistors can be connected in parallel with the first fine-tuning resistor and the second fine-tuning resistor, respectively, and a single-way switch can be set on the parallel branches of the first and second fine-tuning resistors, respectively. A microcontroller is used to control the opening and closing of the single-way switch to achieve the connection and disconnection of the first and second fine-tuning resistors, which is used to fine-tune the voltage difference between VIP and VIN.

[0043] Furthermore, the resistance values ​​of the first and second fine-tuning resistors are integer multiples of the sum of a plurality of voltage-dividing resistors. This configuration can simplify circuit design and accurately control the voltage difference.

[0044] Furthermore, the resistance values ​​of the voltage-dividing resistors are the same, and the resistance values ​​of the first common-mode voltage resistor and the second common-mode voltage resistor are the same. This configuration is convenient for selecting the intermediate voltage-dividing nodes and controlling the pressure difference, and meets the requirements of the resistive pressure sensor for the common-mode voltage.

[0045] Furthermore, in a specific implementation, there are five voltage-dividing resistors, the voltage between the first common-mode voltage resistor and the voltage-dividing resistor is zero, and the voltage between the voltage-dividing resistor and the second common-mode voltage resistor is full-scale voltage. By adopting this configuration, the number of voltage-dividing nodes is increased, the accuracy of pressure difference selection is improved, and the accuracy of generated calibration coefficients is thereby improved.

[0046] Furthermore, the multi-way analog switch also includes

[0047] The positive terminal is connected to the power supply and connected to the ground through a capacitor;

[0048] Two negative terminals, connected to the ground;

[0049] Low level enable port, connected to ground.

[0050] Further, the microcontroller processing circuit includes:

[0051] A plurality of multi-way switch connection ports are respectively connected to the address selection ports of the multi-way analog switch, and are used to control the states of the address selection ports, and further control the selection channels;

[0052] Two single-way switch connection ports are respectively connected to the two single-way switches to control the opening and closing of the two single-way switches;

[0053] A voltage acquisition port is connected to a voltage dividing node between the voltage dividing resistors of the bridge voltage generating circuit, and is used to collect the node voltage and then determine the current value of the bridge voltage generating circuit.

[0054] As another specific embodiment of the present invention, a method for simulating different resistive pressure sensors to generate calibration coefficients is provided, comprising the following steps:

[0055] Count the minimum zero voltage value and the full-scale voltage value of a batch of resistive pressure sensors in the actual use range;

[0056] Determine the difference between the positive and negative pressure inputs of the conditioning conversion circuit with the full-scale voltage value, set the number and resistance value of the voltage divider resistors, and calculate the maximum current value of the bridge voltage generating circuit;

[0057] Calculate the common mode voltage resistance value based on the reference voltage value of the conditioning conversion circuit and the maximum current value of the bridge voltage generating circuit;

[0058] Analyze the voltage difference of each voltage division node, and determine the zero voltage node and the full-scale voltage node in the voltage division node;

[0059] The voltage divider node of the bridge voltage generating circuit is selected by a multi-way analog switch, and the output of the resistive pressure sensor is simulated by using the zero-position voltage, the full-scale voltage and the intermediate voltage therebetween, and input into the conditioning conversion circuit. The calibration coefficient of the conditioning conversion circuit is generated by the least squares fitting method, and the calibration coefficient is configured in the conversion chip of the conditioning conversion circuit.

[0060] Furthermore, a microcontroller is used to monitor the voltage of an intermediate voltage-dividing node of the bridge voltage generating circuit. When the voltage does not meet the requirements, a fine-tuning resistor is introduced, that is, a fine-tuning resistor is connected in parallel at both ends of the series voltage-dividing resistor, and the resistance value or number of the parallel fine-tuning resistor is adjusted so that the voltage of the intermediate voltage-dividing node meets the requirements.

[0061] Furthermore, the output current of the conditioning conversion circuit corresponding to each voltage-dividing node of the bridge voltage generating circuit is calculated when it is selected, and the accuracy of the calibration coefficient generated by simulating different resistive pressure sensors is verified.

[0062] like Figures 1 to 5 As shown, according to a specific embodiment of the present invention, a circuit for quickly generating calibration coefficients by a conditioning conversion circuit board for an analog resistive pressure sensor is provided, which mainly includes a multi-channel analog switch, a bridge voltage generating circuit, a single-channel switch circuit, a microcontroller processing circuit, and a conditioning conversion circuit. Among them,

[0063] 1) D1 is a multi-way analog switch, where:

[0064] Pin 16 (VDD) is the positive power supply, which can be connected to a 3.3V or 5V power supply. It is connected to capacitor C1 (0.1uf) and then to ground (GND), mainly used for power supply filtering;

[0065] Pin 7 (VEE) and pin 8 (VSS) are the negative poles of the power supply and are directly connected to the ground;

[0066] Pin 6 (EE), which is connected to ground (GND), low level enable;

[0067] Pin 13 (Y0), pin 14 (Y1), pin 15 (Y2), pin 12 (Y3), pin 1 (Y4), pin 5 (Y5), pin 2 (Y6), and pin 4 (Y7) are used as independent input and output pins. For example, in this example, 5 terminals from Y0 to Y4 are selected to connect to the bridge voltage generation circuit to adjust the voltage between VIP and VIN.

[0068] Pin 3 (Z) is a common input / output port, which can be connected to the negative voltage output VIN of the conditioning conversion circuit.

[0069] Pin 11 (A0), pin 10 (A1), and pin 9 (A2) are used to select channels. They have two states, 0 and 1, for a total of 8 states. For example, A0=0, A1=0, A2=0, represents that the Y0 channel is connected to Z; A0=0, A1=0, A2=1, represents that the Y1 channel is connected to Z; A0=0, A1=1, A2=0, represents that the Y2 channel is connected to Z; A0=0, A1=1, A2=1, represents that the Y3 channel is connected to Z; A0=1, A1=0, A2=0, represents that the Y4 channel is connected to Z; and so on.

[0070] 2) A bridge voltage generating circuit is used to generate a zero voltage, an intermediate voltage, and a full-scale voltage, wherein the circuit mainly includes a plurality of resistors. In order to meet the common-mode voltage requirements of the resistive pressure sensor, the common-mode voltage resistors R1 and R7 can take the same value, because the VREF reference voltage is about 3.3V, and the voltage difference of the full-scale VIP-VIN of the resistive pressure sensor is at the mV level, the resistance values ​​of the common-mode voltage resistors R1 and R7 can be taken in kilo-ohms, and the voltage divider resistors R2, R3, R4, R5, and R6 can also take the same value, and R2 to R6 can be taken in about 100 ohms. To facilitate the calculation of current, the fine-tuning resistors R9 and R10 are preferably integer multiples of the sum of R2, R3, R4, R5, and R6, and R26 = R2+R3+R4+R5+R6.

[0071] VREF is the reference voltage provided by the conditioning conversion circuit; VREF is connected to R1 and then connected to VIP, where R1 is connected in series with R2, R3, ... R7. Y0, Y1, Y2, Y3, Y4, Y5 are connected to R2, R3, R4, R5, R6, R7 in sequence. For example, when the multi-channel analog switch is enabled and A0 = A1 = A2 = 0, Y0 is connected to the common input and output port Z, that is, Y0 is connected to VIN at this time, and the voltage difference between VIP and VIN is zero; when A0 = A1 = 0, A2 = 1, the Y1 channel is connected to Z, Y1 is connected to VIN, and the voltage difference between VIP and VIN is the voltage drop across R2.

[0072] R9 is connected to the switch circuit in D2. R10 is connected to the switch circuit in D3. R9 and R10 are used to fine-tune the voltage difference between VIP and VIN. When the switch connected to R9 is turned on and the switch connected to R10 is turned off, the total resistance of the circuit is Rtotal = R1 + R7 + R9 / / R26; when the switch connected to R9 is turned off and the switch connected to R10 is turned on, the total resistance of the circuit is Rtotal = R1 + R7 + R10 / / R26; when the switch connected to R9 is turned on and the switch connected to R10 is also turned on, the total resistance of the circuit is Rtotal = R1 + R7 + R9 / / R10 / / R26.

[0073] 3) Single switch circuit

[0074] The single-way switch circuits D2 and D3 are equivalent to two control switches. When enabled, the switch is turned on, and when disabled, the switch is not turned on. For example, when R9_EN is enabled, R9-1 and R9-2 are turned on; when R10_EN is enabled, R10-1 and R10-2 are turned on. The enabling of the two single-way switches is controlled by the output pin of the microcontroller D4.

[0075] 4) Microcontroller processing circuit

[0076] The microcontroller serves as the overall dispatching unit of the analog circuit. It controls the address selection signal of the multi-way switch, controls the enable of the two single-way switch circuits, and also collects the voltage value of the Y4 node of the bridge voltage generating circuit.

[0077] The microcontroller collects the voltage value of point Y4 and can pick up the current on the main line of the entire circuit. If it is determined that the current is too small, R9_EN and R10_EN can be turned on for fine-tuning.

[0078] 5) Conditioning conversion circuit

[0079] The conditioning conversion circuit can convert the output pressure difference of the resistive pressure sensor into a 4-20mA output. It can generate a reference voltage VREF to power the pressure core, and can convert the difference between the positive pressure output VIP and the negative pressure output VIN of the pressure core into a current signal output. LOOP+ is a 4-20mA positive output, and LOOP- is a 4-20mA negative output.

[0080] By using this configuration, a method for quickly generating calibration coefficients for a simulated resistive pressure sensor to complete the conditioning conversion circuit board is provided. This method can use at least 3 points to generate calibration coefficients. The three input points correspond to the 4-20mA output one by one, and then the calibration coefficients are obtained through the conditioning conversion circuit. The selection method of the three input points is combined with the above circuit and is described as follows:

[0081] 1) Record the minimum zero voltage value Zmin of this batch of resistive pressure sensors and the voltage value Mmax corresponding to the maximum full scale of the actual use range. For example, if the actual use requirement of water pressure is Pmin~Pmax, check the pressure core of this batch, and at Pmin pressure, record the minimum value of the voltage values ​​output by all pressure sensors as Zmin; at Pmax pressure, record the maximum value of the voltage values ​​output by all pressure sensors as Mmax.

[0082] 2) Based on the value of Mmax, the difference between VIP and VIN can be obtained, which is divided by R26 (assuming R2 = R3 = R4 = R5 = R6 = 100) to obtain the maximum current value on the bus at this time. If VREF is known, R1 and R7 can be calculated.

[0083]

[0084] VIP-VIN=Mmax

[0085] Among them, R26 can be set manually.

[0086] 3) If the absolute value of the voltage between VIP and Y1 is less than Zmin, the voltage difference between VIP and Y1 is used as the zero input voltage. If the absolute value of the voltage between VIP and Y1 is greater than Zmin, the voltage difference between VIP and Y0 is used as the zero input voltage. At this time, the 4-20mA output corresponding to this voltage should be 4mA.

[0087] 4) Calculate the absolute value of the voltage between VIP and Y4. If it is greater than Mmax, the voltage difference between VIP and Y4 is used as the full-scale input voltage. If it is less than or equal to Mmax, the voltage difference between VIP and Y5 is used as the full-scale input voltage. At this time, the 4-20mA output corresponding to this voltage should be 20mA;

[0088] 5) Based on the determined zero and full-scale values, the intermediate value can be selected manually. For example, VIP and Y1 are used as zero input, corresponding to 4mA, and VIP and Y5 are used as full-scale input, corresponding to 20mA. The intermediate value can be VIP and Y3, corresponding to 12mA. If the intermediate value is VIP and Y2, the corresponding current value is 8mA.

[0089] After completing the above steps, the calibration coefficients of the conditioning conversion circuit can be written using the calibration software that comes with the conditioning conversion chip.

[0090] A method for quickly generating calibration coefficients by completing a conditioning conversion circuit board of an analog resistive pressure sensor, wherein a switch circuit corresponding to R9 and R10 in the method needs to be turned on only when the pressure difference needs to be fine-tuned.

[0091] A method for quickly generating calibration coefficients by completing a conditioning conversion circuit board for an analog resistive pressure sensor, wherein the corresponding calculation formulas for voltage and 4-20 mA in this method are as follows:

[0092] The subscript L of the voltage divider node Y corresponding to the zero voltage 零 The subscript of the voltage divider node corresponding to the full-scale voltage is L. 满 , then the difference of 16mA corresponding to 4 to 20 is divided into L 差 =(L 满 -L 零 ) in equal parts.

[0093] The intermediate value can take other values ​​except zero point and full scale, and its corresponding subscript L 中 The corresponding current is 4mA+(L 中 -L 零 )*16mA / L 差 ; If VIN is Y0, it corresponds to 4mA, VIN is Y5 and the full scale is 20mA. When the intermediate value corresponds to VIN Y1, the corresponding current is 4mA+16 / 5mA.

[0094] The theoretical results obtained by the above calculation method are compared with the calibration coefficients quickly generated by simulating different resistive pressure sensors in the present invention, which can verify the accuracy of the method for quickly generating calibration coefficients in the present invention.

[0095] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0096] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A circuit for simulating different resistive pressure sensors to generate calibration coefficients, characterized in that: It includes a bridge voltage generating circuit, a multi-channel analog switch, a microcontroller, and a conditioning and conversion circuit; The bridge voltage generating circuit comprises a first common-mode voltage resistor, at least two voltage-dividing resistors, and a second common-mode voltage resistor connected in series in sequence, wherein one end of the first common-mode voltage resistor away from the voltage-dividing resistor is connected to a reference voltage of a conditioning and conversion circuit, one end of the second common-mode voltage resistor away from the voltage-dividing resistor is grounded, and the first common-mode voltage resistor, the second common-mode voltage resistor and adjacent voltage-dividing resistors, and the adjacent voltage-dividing resistors are used as voltage-dividing nodes; The multi-way analog switch includes an input / output selection port, an address selection port, and a common input / output port; the input / output selection ports are at least three and connected to different voltage-dividing nodes of the voltage-dividing resistor of the bridge circuit; the common input / output port is connected to the VIN port of the conditioning conversion circuit; the address selection ports are at least two, and the state of the address selection ports is controlled by a microcontroller to realize the control of the gating mode of the input / output selection ports; The VIP port of the conditioning and conversion circuit is connected to the zero-position voltage dividing node of the bridge voltage generating circuit.

2. The circuit for generating a calibration coefficient according to claim 1, characterized in that: The voltage-dividing resistors connected in series are respectively connected in parallel with the first and second fine-tuning resistors, and a single-way switch is respectively arranged on the parallel branches of the first and second fine-tuning resistors.

3. The circuit for generating a calibration coefficient according to claim 2, characterized in that: The resistance values ​​of the first and second fine-tuning resistors are integer multiples of the sum of a plurality of voltage-dividing resistors.

4. The circuit for generating a calibration coefficient according to claim 1, characterized in that: The resistance values ​​of the voltage-dividing resistors are the same, and the resistance values ​​of the first common-mode voltage resistor and the second common-mode voltage resistor are the same.

5. The circuit for generating a calibration coefficient according to claim 1, characterized in that: The multi-way analog switch also includes The positive terminal is connected to the power supply and connected to the ground through a capacitor; Two negative terminals, connected to the ground; Low level enable port, connected to ground.

6. The circuit for generating calibration coefficients according to claim 1, characterized in that: The microcontroller also includes a voltage acquisition port connected to a voltage dividing node between voltage dividing resistors in the bridge voltage generating circuit, and is used to monitor the current value of the bridge voltage generating circuit by acquiring the voltage of the voltage dividing node.

7. A method for simulating different resistive pressure sensors to generate calibration coefficients, characterized in that: Using the circuit described in any one of claims 1 to 6, the method for generating the calibration coefficient comprises the following steps: Count the minimum zero voltage value and the full-scale voltage value of a batch of resistive pressure sensors in the actual use range; Determine the difference between the positive and negative pressure inputs of the conditioning conversion circuit with the full-scale voltage value, set the number and resistance value of the voltage divider resistors, and calculate the maximum current value of the bridge voltage generating circuit; Calculate the common mode voltage resistance value based on the reference voltage value of the conditioning conversion circuit and the maximum current value of the bridge voltage generating circuit; Analyze the voltage difference of each voltage division node, and determine the zero voltage voltage division node and the full-scale voltage voltage division node among the voltage division nodes; The voltage-dividing node of the bridge voltage generating circuit is selected by a multi-way analog switch, and the output of the resistive pressure sensor is simulated by using the zero-position voltage, the full-scale voltage and the intermediate voltage therebetween, and the input is input into the conditioning conversion circuit. The calibration coefficient of the conditioning conversion circuit is generated by the least squares fitting method, and the calibration coefficient is configured in the conditioning conversion circuit.

8. The method for generating a calibration coefficient according to claim 7, characterized in that: The method also includes the steps of using a microcontroller to monitor the voltage of an intermediate voltage-dividing node of the bridge voltage generating circuit, and when the voltage does not meet the requirements, introducing a fine-tuning resistor, adjusting the resistance value or the number of parallel fine-tuning resistors so that the voltage of the intermediate voltage-dividing node meets the requirements.

9. The method for generating a calibration coefficient according to claim 7, characterized in that: The method also includes calculating the output current of the conditioning conversion circuit corresponding to each voltage-dividing node of the bridge voltage generating circuit when it is selected, and verifying the accuracy of the generated calibration coefficient.

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