A circuit and method for generating calibration coefficients for an analog variable resistance pressure sensor

Abstract

The application provides a circuit and method for generating calibration coefficients of different resistance type pressure sensors, which comprises a bridge voltage generating circuit, a multi-channel analog switch, a microcontroller and a conditioning 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, and the resistors are connected as voltage dividing nodes; the multi-channel analog switch is connected with different voltage dividing nodes through multiple input and output selection ports, and the common input and output port is connected with the VIN port of the conditioning conversion circuit, and the microcontroller is used to control the address selection port state to realize the voltage dividing node gating mode; and the VIP port of the conditioning conversion circuit is connected with the zero voltage dividing node of the bridge voltage generating circuit. The application can solve the technical problems of the prior art, such as the complicated operation caused by the one-to-one pairing of the conditioning conversion circuit board and the pressure sensor when generating the calibration coefficients, the difficulty in realizing batch automation, and the easy artificial damage to the pressure sensor.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, and in particular to a circuit and method for simulating calibration coefficients of different resistive pressure sensors. Background Technology

[0002] Water level monitoring is one of the most important parameters in geothermal remote dynamic monitoring. It typically employs a resistive pressure sensor to convert water pressure into a voltage signal. This voltage signal is then converted into a 4-20mA current signal or an RS485 digital signal via a conditioning and conversion circuit board, and transmitted over a long cable to a remote terminal on the well for data acquisition. The conditioning and conversion circuit must first be connected to the resistive pressure sensor. Using its built-in calibration software, at least two (typically zero point and full scale) or three (typically zero point, midpoint, and full scale) pressure data points from the sensor are obtained (input via a pressure calibration device). Curve fitting is then performed to obtain the calibration coefficients for the conditioning and conversion circuit, which are then configured into the circuit. Only then does the conditioning and conversion circuit possess real-time conditioning and conversion capabilities; otherwise, it functions like an unprogrammed microcontroller, rendering it ineffective.

[0003] Because different resistance pressure sensors have different zero points and full-scale ranges, most current methods involve pairing resistance pressure sensors with conditioning and conversion circuits, manually inputting different air pressure values, and then generating calibration coefficients by fitting the data. This method is not easy to mass-produce, has poor interchangeability, and the pressure sensor, being a relatively expensive component, is susceptible to damage due to improper manual operation during the calibration phase. Summary of the Invention

[0004] This invention aims to solve the technical problems of the cumbersome process of pairing pressure sensors one by one during coefficient calibration generation for conditioning conversion circuit boards, which makes batch automation difficult and easily leads to human-caused damage to pressure sensors. This invention provides a circuit and method for simulating the generation of calibration coefficients from different resistive pressure sensors. By simulating a bridge circuit of a real resistive pressure sensor, it automatically switches between zero point, full scale, and intermediate values, automatically generating standard coefficients for the conditioning conversion circuit board. This method can quickly automate calibration coefficient configuration, effectively improving production efficiency and reducing human-caused damage.

[0005] This invention provides a circuit for simulating calibration coefficients generated by different resistive pressure sensors, including a bridge voltage generation circuit, a multiplex analog switch, a microcontroller, and a conditioning and conversion circuit;

[0006] The bridge voltage generation circuit includes a first common-mode voltage resistor, at least two voltage divider resistors, and a second common-mode voltage resistor connected in series. The end of the first common-mode voltage resistor away from the voltage divider resistors is connected to the reference voltage of the conditioning and conversion circuit. The end of the second common-mode voltage resistor away from the voltage divider resistors is grounded. The first common-mode voltage resistor, the second common-mode voltage resistor, and the adjacent voltage divider resistors, as well as the adjacent voltage divider resistors, serve as voltage divider nodes.

[0007] The multi-channel analog switch includes an input / output selection port, an address selection port, and a common input / output port; the input / output selection ports have at least three connections, which are connected to different voltage divider nodes of the voltage divider resistors in the bridge circuit; the common input / output port is connected to the VIN port of the conditioning conversion circuit; the address selection ports have at least two connections, and the state of the address selection ports is controlled by a microcontroller to control the selection mode of the input / output selection ports.

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

[0009] Furthermore, the series-connected voltage divider resistors are connected in parallel with the first and second fine-tuning resistors, and a single-channel switch is provided on each of 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 the multiple voltage divider resistors.

[0011] Furthermore, the resistance values ​​of each of the voltage divider 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 multiplex analog switch also includes

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

[0014] The two negative terminals are connected to ground.

[0015] The low-level enable port is 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 generation circuit. By acquiring the voltage at the voltage dividing node, the current value of the bridge voltage generation circuit can be monitored.

[0017] This invention also provides a method for generating calibration coefficients by simulating different resistive pressure sensors. Using the circuit described above, the method for generating calibration coefficients includes the following steps:

[0018] The minimum zero-point voltage value and the full-scale voltage value of a certain batch of resistance pressure sensors were statistically analyzed.

[0019] Determine the positive and negative pressure input difference of the conditioning conversion circuit based on 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 generation 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 generation circuit;

[0021] Analyze the voltage difference at each voltage divider node to determine the zero-voltage voltage divider node and the full-scale voltage voltage divider node.

[0022] The voltage divider node of the bridge voltage generation circuit is selected by a multi-channel analog switch. The output of the resistive pressure sensor is simulated by the zero-point voltage, the full-scale voltage, and the intermediate voltage between the two. The input is then fed into the conditioning and conversion circuit. The calibration coefficient of the conditioning and conversion circuit is generated by fitting using the least squares method. This calibration coefficient is then configured in the conditioning and conversion circuit.

[0023] Furthermore, it also includes the step of using a microcontroller to monitor the voltage of a certain intermediate voltage divider node in the bridge voltage generation circuit, and when the voltage does not meet the requirements, introducing a fine-tuning resistor to adjust the resistance value or number of parallel fine-tuning resistors so that the voltage of the intermediate voltage divider node meets the requirements.

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

[0025] The beneficial effects of this invention are:

[0026] This invention provides a circuit and method for generating calibration coefficients using different resistive pressure sensors. A microcontroller controls the selection of multiple analog switch channels, automatically adjusting the zero-point voltage, intermediate-point voltage, full-scale voltage, and other voltage values ​​of the bridge voltage generation circuit. This, in turn, adjusts the differential pressure output from the bridge voltage generation circuit to the conditioning and conversion circuit. The conditioning and conversion circuit then uses the least squares method to fit the collected differential pressure values ​​to generate calibration coefficients. This circuit can automatically switch between zero-point, full-scale, and intermediate-point settings without requiring a pressure calibration device. Furthermore, it can automatically set the zero-point, intermediate-point, and full-scale values ​​based on the resistive pressure sensor's range, effectively improving production efficiency and reducing human error.

[0027] This invention incorporates a fine-tuning resistor in the bridge voltage generation circuit to finely adjust the voltage difference between VIP and VIN. By designing the parameters of the voltage divider resistors and common-mode voltage resistors in the bridge voltage generation circuit, the accuracy of the voltage difference control is increased. Attached Figure Description

[0028] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

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

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

[0031] Figure 3 A schematic diagram of a single-channel switching circuit according to a specific embodiment of the present invention is shown;

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

[0033] Figure 5 A schematic diagram of the conditioning and switching circuit provided according to a specific embodiment of the present invention is shown. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0037] As a specific embodiment of the present invention, a circuit for simulating the generation of calibration coefficients from different resistive pressure sensors is provided, including a bridge voltage generation circuit, a multiplexer analog switch, a microcontroller, and a conditioning and conversion circuit, specifically:

[0038] The bridge voltage generation circuit includes a first common-mode voltage resistor, at least two voltage divider resistors, and a second common-mode voltage resistor connected in series. The end of the first common-mode voltage resistor away from the voltage divider resistors is connected to the reference voltage VREF of the conditioning and conversion circuit. The end of the second common-mode voltage resistor away from the voltage divider resistors is grounded. The first common-mode voltage resistor, the second common-mode voltage resistor and the adjacent voltage divider resistors, and the adjacent voltage divider resistors serve as voltage divider 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, which are connected to different voltage divider nodes of the voltage divider resistors in the bridge circuit. The common input / output port is connected to the negative voltage input VIN port of the conditioning and conversion circuit. There are at least two address selection ports, which include two states: 0 and 1. The state of the address selection ports is controlled by the microcontroller to control the selection mode of the input / output selection ports.

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

[0041] The circuit provided by this invention, which simulates the generation of calibration coefficients for different resistive pressure sensors, uses a bridge voltage generation circuit to generate zero-point voltage, intermediate-point voltage, and full-scale voltage. A microcontroller controls the selection of multiple analog switch channels, thereby controlling the differential voltage output from the bridge voltage generation circuit to the conditioning and conversion circuit, facilitating rapid generation of calibration coefficients. This circuit can automatically switch between zero-point, full-scale, and intermediate-point settings without requiring a pressure calibration device. Furthermore, it can automatically set the zero-point, intermediate-point, and full-scale values ​​based on the resistive pressure sensor's range, effectively improving production efficiency and reducing human error.

[0042] Furthermore, the two ends of the multiple series voltage divider resistors can be connected in parallel with the first and second fine-tuning resistors, respectively. A single-channel switch is set on each of the parallel branches of the first and second fine-tuning resistors. A microcontroller is used to control the opening and closing of the single-channel switches to realize 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 first and second fine-tuning resistors have resistance values ​​that are integer multiples of the sum of the multiple voltage divider resistors. This configuration simplifies circuit design and allows for precise control of the voltage difference.

[0044] Furthermore, all voltage divider resistors have the same resistance value, and the first common-mode voltage resistor and the second common-mode voltage resistor have the same resistance value. This configuration facilitates the selection of intermediate voltage divider nodes and differential voltage control, while also meeting the common-mode voltage requirements of resistive pressure sensors.

[0045] Furthermore, in one specific implementation, there are five voltage divider resistors. The voltage between the first common-mode voltage resistor and the voltage divider resistors is zero-point voltage, and the voltage between the voltage divider resistors and the second common-mode voltage resistors is full-scale voltage. This configuration increases the number of voltage divider nodes, improves the accuracy of differential voltage matching, and thus enhances the accuracy of generating calibration coefficients.

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

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

[0048] The two negative terminals are connected to ground.

[0049] The low-level enable port is connected to ground.

[0050] Furthermore, the microcontroller processing circuitry includes:

[0051] Multiple multiplexer connection ports are connected to the address selection ports of multiplexer analog switches, respectively, to control the state of the address selection ports and thus control the selection channels;

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

[0053] A voltage acquisition port is connected to a voltage divider node between the voltage divider resistors of the bridge voltage generation circuit. It is used to acquire the node voltage and then determine the current value of the bridge voltage generation circuit.

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

[0055] The minimum zero-point voltage value and the full-scale voltage value of a certain batch of resistance pressure sensors were statistically analyzed.

[0056] Determine the positive and negative pressure input difference of the conditioning conversion circuit based on 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 generation 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 generation circuit;

[0058] Analyze the voltage difference at each voltage divider node to determine the zero-voltage node and the full-scale voltage node among the voltage divider nodes;

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

[0060] Furthermore, a microcontroller is used to monitor the voltage of a certain intermediate voltage divider node in the bridge voltage generation 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 across the series voltage divider resistors. The resistance value or number of the parallel fine-tuning resistors is adjusted so that the voltage of the intermediate voltage divider node meets the requirements.

[0061] Furthermore, the output current of the conditioning and conversion circuit corresponding to each voltage divider node of the bridge voltage generation circuit is calculated to verify the accuracy of the calibration coefficients generated by the simulated different resistive pressure sensors.

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

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

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

[0065] Pins 7 (VEE) and 8 (VSS) are the negative terminals for power supply and are directly connected to ground.

[0066] Pin 6 (EE) is connected to ground (GND) and is enabled by a low level.

[0067] Pins 13 (Y0), 14 (Y1), 15 (Y2), 12 (Y3), 1 (Y4), 5 (Y5), 2 (Y6), and 4 (Y7) are used as independent input / output pins. For example, in this example, five terminals, 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] Pins 11 (A0), 10 (A1), and 9 (A2) are used to select channels, each with two states (0 and 1), for a total of 8 states. For example, A0=0, A1=0, A2=0 means that channel Y0 is connected to Z; A0=0, A1=0, A2=1 means that channel Y1 is connected to Z; A0=0, A1=1, A2=0 means that channel Y2 is connected to Z; A0=0, A1=1, A2=1 means that channel Y3 is connected to Z; A0=1, A1=0, A2=0 means that channel Y4 is connected to Z; and so on.

[0070] 2) The bridge voltage generation circuit is used to generate zero-point voltage, intermediate-value voltage, and full-scale voltage. This circuit mainly includes multiple resistors. To meet the common-mode voltage requirements of the resistive pressure sensor, the common-mode voltage resistors R1 and R7 can have the same value. Since the VREF reference voltage is approximately 3.3V, and the voltage difference between the full-scale VIP and VIN of the resistive pressure sensor is in the mV range, the resistance values ​​of the common-mode voltage resistors R1 and R7 can be in the kiloohm range. The voltage divider resistors R2, R3, R4, R5, and R6 can also have the same value, with R2 to R6 around 100 ohms. For ease of current calculation, the fine-tuning resistors R9 and R10 should ideally be integer multiples of the sum of R2, R3, R4, R5, and R6, denoted as R26 = R2 + R3 + R4 + R5 + R6.

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

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

[0073] 3) Single-channel switch circuit

[0074] In the single-channel switch circuit, D2 and D3 act as two control switches. When enabled, the switches are on; when disabled, they are off. For example, when R9_EN is enabled, R9-1 and R9-2 are on; when R10_EN is enabled, R10-1 and R10-2 are on. The enabling of the two single-channel switches is controlled by the output pin of microcontroller D4.

[0075] 4) Microcontroller processing circuit

[0076] As the main scheduling unit of the analog circuit, the microcontroller controls the address selection signal of the multiplexer, the enable of the two single-channel switch circuits, and also collects the voltage value of node Y4 of the bridge voltage generation circuit.

[0077] The microcontroller collects the voltage value at point Y4 and can pick up the current in the main circuit. If it determines that the current is too low, it can turn on R9_EN and R10_EN for fine-tuning.

[0078] 5) Conditioning and switching circuit

[0079] The conditioning and conversion circuit converts the output differential pressure of the resistive pressure sensor into a 4-20mA output. It generates a reference voltage VREF to power the pressure core and converts 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] This configuration provides a method for rapidly generating calibration coefficients on a conditioning conversion circuit board using an analog resistance pressure sensor. This method can generate calibration coefficients using at least three input points, with each of the three input points corresponding to a 4-20mA output. The calibration coefficients are then obtained through the conditioning conversion circuit. The method for selecting the three input points, combined with the circuit described above, is described below:

[0081] 1) Record the minimum zero-point voltage value Zmin and the voltage value Mmax corresponding to the maximum full-scale range of the actual operating range for this batch of resistance pressure sensors. For example, if the actual water pressure requirement is Pmin to Pmax, then check the pressure cores of this batch. At pressure Pmin, record the minimum voltage value among all the voltage values ​​output by all pressure sensors as Zmin; at pressure Pmax, record the maximum voltage value among all the voltage values ​​output by all pressure sensors as Mmax.

[0082] 2) The difference between VIP and VIN can be obtained from the value of Mmax. Dividing this difference by R26 (assuming R2 = R3 = R4 = R5 = R6 = 100) yields the maximum current value on the bus at this point. Given VREF, R1 and R7 can be calculated.

[0083]

[0084] VIP-VIN = Mmax

[0085] R26 can be manually set.

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

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

[0089] After completing the above steps, the calibration coefficients of the conditioning and conversion circuit can be written using the calibration software built into the conditioning and conversion chip.

[0090] A method for rapidly generating calibration coefficients on a conditioning conversion circuit board using an analog resistance pressure sensor, wherein the switching circuits corresponding to R9 and R10 in this method only need to be turned on when fine-tuning of the differential pressure is required.

[0091] A method for rapidly generating calibration coefficients on a conditioning conversion circuit board using an analog resistance pressure sensor, wherein the calculation formula for the voltage corresponding to 4-20mA in this method is as follows:

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

[0093] The intermediate value can take any value other than zero 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; if VIN is Y5, it corresponds to 20mA at full scale; when the intermediate value corresponds to VIN Y1, the corresponding current is 4mA + 16 / 5mA.

[0094] The theoretical results obtained through the above calculation method are compared with the calibration coefficients rapidly generated by simulating different resistive pressure sensors in this invention, which verifies the accuracy of the method for rapidly generating calibration coefficients described in this invention.

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

[0096] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A circuit for simulating calibration coefficients from different resistive pressure sensors, characterized in that, The circuit comprises a bridge voltage generating circuit, a multi-channel analog switch, a microcontroller, and a conditioning 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. The multi-channel analog switch comprises an input-output selection port, an address selection port, and a common input-output port. The VIP port of the conditioning conversion circuit is connected to the zero voltage dividing node of the bridge voltage generating circuit. The first and second trimming resistors are connected in parallel with the voltage dividing resistors. The resistance values of the first and second trimming resistors are integer multiples of the sum of the resistance values of the voltage dividing resistors.

2. The circuit for generating calibration coefficients according to claim 1, wherein, The resistance values of the voltage dividing resistors are the same, and the resistance values of the first and second common-mode voltage resistors are the same.

3. The circuit for generating calibration coefficients according to claim 1, wherein, The multi-channel analog switch further comprises The positive port is connected to a power supply and to ground through a capacitor. The two negative ports are connected to ground. The low-level enable port is connected to ground.

4. The circuit for generating calibration coefficients according to claim 1, wherein, The microcontroller further comprises a voltage collection port connected to a certain voltage dividing node between the voltage dividing resistors of the bridge voltage generating circuit.

5. A method of generating calibration coefficients for an analog variable resistance pressure sensor, comprising: The method for generating the calibration coefficient comprises the following steps: The minimum zero voltage value and the full-scale voltage value of a batch of resistance pressure sensors are counted. The positive and negative pressure input difference of the conditioning conversion circuit is determined based on the full-scale voltage value, and the number and resistance values of the voltage dividing resistors are set. The maximum current value of the bridge voltage generating circuit is calculated. The common-mode voltage resistor value is calculated based on the reference voltage value of the conditioning conversion circuit and the maximum current value of the bridge voltage generating circuit. The voltage differences of the voltage dividing nodes are analyzed to determine the zero voltage dividing node and the full-scale voltage dividing node.

6. The method of generating calibration coefficients according to claim 5, wherein, The voltage dividing nodes of the bridge voltage generating circuit are selected by the multi-channel analog switch, and the zero voltage, the full-scale voltage, and the intermediate voltage between the two are used to simulate the output of the resistance pressure sensor and input into the conditioning conversion circuit. The calibration coefficient of the conditioning conversion circuit is generated by the least square method, and the calibration coefficient is configured in the conditioning conversion circuit. The voltage of a certain intermediate voltage dividing node of the bridge voltage generating circuit is monitored by the microcontroller, and when the voltage does not meet the requirements, the trimming resistors are introduced to adjust the resistance values or the number of the parallel trimming resistors so that the voltage of the intermediate voltage dividing node meets the requirements.

7. The method of generating calibration coefficients according to claim 5, wherein, The step of verifying the accuracy of the generated calibration coefficient also includes calculating the output current of the conditioning conversion circuit corresponding to the selection of each voltage division node of the bridge voltage generating circuit.

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