Circuit for reading pressure sensor value by module to realize sudden change prevention

Abstract

The utility model relates to an anti-abrupt change circuit, in particular to an anti-abrupt change circuit for reading a pressure sensor value by a module, which comprises a pressure sensor and an MCU (Microprogrammed Control Unit) chip for reading an AD (Analog to Digital) value of the pressure sensor, a resistor R1 and a resistor R2 are also arranged; the resistor R1 and the resistor R2 form a voltage division circuit to reduce the voltage output by the pressure sensor; a current-limiting resistor R3 is connected in series before being connected to an AD detection pin of the chip; a capacitor C1 and a capacitor C2 are arranged; two diodes D1 are arranged between the current limiting resistor R3 and the MCU chip; the problem of power supply of the MCU chip can be solved, and an anti-abrupt change function is realized.

Description

Technical Field

[0001] The utility model relates to an anti-mutation circuit, in particular to an anti-mutation circuit realized by a module reading a pressure sensor value. Background Art

[0002] The anti-mutation circuit is a device used to prevent sudden voltage in the circuit. Sudden voltage may cause damage to the components and equipment in the circuit. Therefore, the role of the anti-mutation circuit is to take immediate measures to limit it to a safe range when a sudden voltage is detected in the circuit; the traditional application is to read the pressure sensor of the module, direct expansion machine, multi-split machine, etc. The MCU directly reads the AD value according to the voltage value of the pressure sensor and converts it into voltage through calculation. Usually, the output range of the pressure sensor used in the module machine is 0.5-4.5V, which exceeds the current 3.3V powered MCU range and will cause damage to the MCU pins; when there is external interference, a sudden change in value will be generated, and the wrong voltage will be read, which cannot meet the actual application of the unit. Utility Model Content

[0003] The utility model aims to provide a module to read the pressure sensor value to realize the anti-mutation circuit. In order to solve the power supply problem of MCU chip and realize the anti-mutation function, this circuit is developed.

[0004] The purpose of the utility model is achieved through the following technical solutions:

[0005] A module reads the pressure sensor value to implement an anti-mutation circuit, comprising a pressure sensor and an MCU chip for reading the AD value of the pressure sensor;

[0006] A resistor R1 and a resistor R2 are also provided;

[0007] The voltage output by the pressure sensor is reduced by forming a voltage divider circuit through the resistors R1 and R2;

[0008] Before connecting to the chip AD detection pin, connect a current limiting resistor R3 in series;

[0009] A capacitor C1 and a capacitor C2 are provided;

[0010] Two diodes D1 are arranged between the current limiting resistor R3 and the MCU chip;

[0011] The capacitor C1 and the capacitor C2 are used to filter higher frequency burrs and other waveforms;

[0012] The MCU chip performs AD conversion on its voltage value;

[0013] The MCU chip reads the AD value 4 times in total, removes the highest and lowest values, takes the middle 2 values ​​and averages them;

[0014] The voltage value is calculated inversely according to the obtained AD value, and then the voltage value before voltage division is calculated; the actual pressure value of the pressure sensor is calculated through the corresponding relationship between the voltage and the pressure value of the pressure sensor;

[0015] The beneficial effects of the utility model are:

[0016] At the output end of the pressure sensor, a resistor network is used to divide the voltage so that the voltage value of the voltage collection pin input to the MCU chip will not be higher than 2.25V; a current-limiting resistor is used to limit the large current entering the MCU chip pin, so that the MCU chip will not be damaged by the large current; a diode device is added to release the instantaneous high positive and negative pressure to protect the MCU chip pin; capacitor filtering is used to eliminate waveforms such as glitches;

[0017] The MCU chip reads the corresponding AD value four times each time, removes the highest and lowest two times, and then averages the remaining two intermediate values ​​to obtain the required AD value; then amplifies the AD value by 2 times; and then reads a round every 1.5 seconds. According to the actual operation of the air-conditioning system, the required pressure value is the average of the sum of the four rounds of readings (if there are less than 4 times before the start, the average is taken according to the actual number of times). Greatly reduce the wrong value and wrong alarm. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The utility model is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0019] Figure 1 This is a block diagram of the principle of the circuit for preventing sudden changes by reading the pressure sensor value of the module of the utility model;

[0020] Figure 2 This is a schematic diagram of a circuit for preventing sudden changes by reading the pressure sensor value of the module of the utility model;

[0021] Figure 3 It is a schematic diagram of the corresponding relationship between the voltage and the pressure value of the pressure sensor of the utility model. DETAILED DESCRIPTION

[0022] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0023] like Figures 1 to 3 As mentioned above, in order to achieve the technical effect of "solving the MCU chip power supply problem and realizing the anti-mutation function", the structure and function of a module reading the pressure sensor value to realize the anti-mutation circuit are described in detail below;

[0024] like Figure 2As shown, a module reads the pressure sensor value to implement an anti-mutation circuit, including a pressure sensor and an MCU chip for reading the AD value of the pressure sensor; this circuit can be applied to the pressure sensors of the general Sanhua or Sensata and other manufacturers with 5V power supply and output 0.5-4.5V range series; the MCU chip reads the corresponding AD value through a high-precision AD converter (12 bits);

[0025] A resistor R1 and a resistor R2 are also provided; a voltage divider circuit is formed by the resistor R1 and the resistor R2 to reduce the voltage output by the pressure sensor; the input voltage is reduced by the resistor series voltage divider so that the voltage of the voltage collection pin input to the MCU will not be higher than 2.25V;

[0026] Before accessing the chip AD detection pin, a current limiting resistor R3 is connected in series; before entering the chip AD detection pin, a current limiting resistor is connected in series to prevent the chip pin from being damaged due to overcurrent; two diodes D1 are arranged between the current limiting resistor R3 and the MCU chip; so that the instantaneous higher positive and negative pressures can be released to protect the chip pins;

[0027] Capacitors C1 and C2 are provided; the capacitors can filter out higher-frequency burrs and other waveforms to ensure the accuracy of the voltage read;

[0028] The MCU chip converts its voltage value into an AD value; the MCU chip reads the AD value 4 times in total, removes the highest and lowest times, takes the middle 2 times and averages them; reduces the values ​​due to interference or errors, and is closer to the required AD value;

[0029] The MCU chip performs average processing, reading once every 1.5 seconds. According to the actual operation of the air conditioning system, the required pressure value is the average of 4 rounds of readings to reduce large pressure fluctuations. This greatly reduces erroneous values ​​and false alarms.

[0030] The voltage value is calculated inversely according to the obtained AD value, and then the voltage value before voltage division is calculated; the actual pressure value of the pressure sensor is calculated through the corresponding relationship between the voltage and the pressure value of the pressure sensor;

[0031] like Figure 3 As shown, the pressure sensor is inserted into PS1, powered by 5V, and the converted voltage is output from pin 2 of PS1. Then, a voltage divider circuit is formed through resistors R1 (4.9K ohms) and R2 (4.9K ohms), so that the voltage is reduced to 0.5 times the original value, and then the current limiting resistor R3 (1K ohm) is used for current limiting protection and coupled to the AD input port of MUC.

[0032] When a higher voltage value is generated, the voltage is quickly released through the two diodes of D1 to release the higher positive and negative voltages, and protect the chip pins; C1 (103, 0.01UF) and C2 (103, 0.01UF) can filter higher frequency burrs and other waveforms. Then enter the AD acquisition port of the MCU for high-precision AD conversion.

[0033] The MCU chip uses a high-precision AD converter to convert its voltage value. Then, in each round of acquisition, it reads 4 AD values, removes the highest and lowest values, takes the middle 2 values ​​and averages them, reduces interference or erroneous values, and obtains a more realistic AD value close to the required value. The voltage value is calculated based on the obtained AD value, and then the voltage value before voltage division is calculated. The actual pressure value of the pressure sensor is calculated through the corresponding relationship between the voltage and the pressure value of the pressure sensor.

[0034] like Figure 3 As shown in the figure, take the reading of the Sensata high pressure sensor as an example. Assume that the AD value read is 1024. According to the AD value of 1024, the voltage value of R2 can be calculated to be 1.25V, and then the output voltage of PS1 can be calculated to be 2.5V. Then check the corresponding table and you can get the pressure value of the pressure sensor to be 27.78barG.

[0035] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A module reads the pressure sensor value to implement an anti-mutation circuit, including a pressure sensor, characterized in that: It also includes an MCU chip for reading the AD value of the pressure sensor; A resistor R1 and a resistor R2 are also provided; The voltage output by the pressure sensor is reduced by forming a voltage divider circuit through the resistors R1 and R2; Before connecting to the chip AD detection pin, connect a current limiting resistor R3 in series; A capacitor C1 and a capacitor C2 are provided; Two diodes D1 are arranged between the current limiting resistor R3 and the MCU chip; The capacitor C1 and the capacitor C2 are used to filter the higher frequency burr waveform; The MCU chip performs AD value conversion on its voltage value.

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