CN115355929A - An array piezoelectric sensor signal processing circuit - Google Patents

Abstract

The invention discloses an array type piezoelectric sensor signal processing circuit, comprising: a main board; a microcontroller is arranged on the main board, and a first analog switch connected with the microcontroller; the first analog switch is connected with a first charge amplification circuit ; The first charge amplifying circuit is composed of a plurality of charge amplifiers; the first charge amplifying circuit is connected with the piezoelectric sensor array for collecting piezoelectric sensor signals; the microcontroller sends an address signal to the first analog switch; the first analog switch Select the signal channel of the piezoelectric sensor to be read according to the address signal, and collect the first analog signal; the microcontroller receives the first analog signal and processes the first analog signal. The signal acquisition of the piezoelectric sensor array can be performed more accurately.

Description

An array piezoelectric sensor signal processing circuit

technical field

The invention relates to the technical field of signal processing circuits, in particular to an array piezoelectric sensor signal processing circuit.

Background technique

At present, sensors have been applied to all aspects of life, such as photoelectric sensors used to measure heart rate in smart bracelets, pressure sensors in smart insoles, etc. Among them, the piezoelectric effect-based sensor, as a self-powered sensor, has the advantages of thinness, low energy consumption, high sensitivity, high signal-to-noise ratio, simple structure, reliable operation, etc., and has broad application prospects. The sensor array can expand the single-point data into a whole higher-dimensional data. Based on the data visualization technology, more effective information can be obtained, which is a trend in the development of sensors.

However, since piezoelectric sensors often have a large impedance, a high-impedance charge amplifier is required to match them. The charge amplifier usually forms an integrating circuit by connecting a capacitor between the negative input section of the amplifier and the output terminal, and a resistor with a larger resistance is connected in parallel at both ends of the capacitor to prevent the amplifier from being saturated. However, the DC component in the circuit will still affect the output of the amplifier.

In addition, since each piezoelectric sensor requires a separate charge amplifier to amplify the signal, the high-impedance op amp is often a single-channel design. At present, the amplifying circuit of the piezoelectric sensor array is often designed as a whole circuit board separately based on the fixed-scale array, which has the problems of large circuit area and large space occupation. For sensor arrays of different sizes and scales, the entire circuit arrangement needs to be redesigned separately, which greatly increases design and manufacturing costs.

Therefore, on the basis of existing piezoelectric sensor signal processing circuits, how to provide a piezoelectric signal processing circuit to flexibly cope with piezoelectric sensor arrays of different scales has become an urgent problem to be solved by those skilled in the art.

Contents of the invention

In view of the above problems, the present invention proposes an array piezoelectric sensor signal processing circuit that at least solves some of the above technical problems, and can more accurately collect signals from the piezoelectric sensor array.

An embodiment of the present invention provides an array piezoelectric sensor signal processing circuit, including: a main board;

The main board is provided with a microcontroller, and a first analog switch connected to the microcontroller;

The first analog switch is connected with a first charge amplifying circuit; the first charge amplifying circuit is composed of a plurality of charge amplifiers; the first charge amplifying circuit is connected with a piezoelectric sensor array for collecting piezoelectric sensor signals ;

The microcontroller sends an address signal to the first analog switch; the first analog switch selects the signal channel of the piezoelectric sensor to be read according to the address signal, and collects the first analog signal; the microcontroller receives the first analog signal and process the first analog signal.

Further, it also includes: an expansion board;

The expansion board is provided with a second charge amplifier circuit and a second analog switch connected to the second charge amplifier circuit; the second charge amplifier circuit is composed of a plurality of charge amplifiers;

The second analog switch is connected to the microcontroller; the second charge amplification circuit is connected to the piezoelectric sensor array to collect piezoelectric sensor signals;

The microcontroller sends an address signal to the second analog switch; the second analog switch selects the signal channel of the piezoelectric sensor to be read according to the address signal, collects a second analog signal, and sends the second An analog signal is sent to the microcontroller.

Further, the expansion board is also provided with an expansion board enable port; the expansion board enable port is connected to the power supply network of the expansion board;

An interface circuit is also provided on the main board; a third analog switch is provided inside the interface circuit;

The third analog switch is respectively connected to the enable port of the expansion board and the microcontroller;

The microcontroller sends an address signal to the third analog switch; the third analog switch selects the signal channel of the piezoelectric sensor to be read according to the address signal, collects a third analog signal, and sends the third an analog signal is sent to the microcontroller;

The microcontroller acquires the quantity and position of expansion boards connected to the main board according to the third analog signal.

Further, the main board is provided with a power supply circuit for supplying power to the main board and the expansion board.

Further, the input port of the microcontroller connected to the interface circuit is provided with a pull-down resistor;

When the main board is connected to the expansion board, the power supply circuit is connected to the power supply network of the expansion board through the enabling port of the expansion board; through the pull-down resistor, the input port connected to the interface circuit The level changes from low level to high level;

The microcontroller acquires the quantity and position of expansion boards connected to the main board according to the acquired level of the third analog signal.

Further, the microcontroller is provided with an analog-to-digital converter for converting the obtained analog signal into a digital signal.

Further, the main board is also provided with a sending circuit for wirelessly sending the digital signal to the terminal.

Further, a serial port is provided inside the microcontroller; the microcontroller transmits the digital signal to the sending circuit through the serial port.

Further, the analog-to-digital converter is an on-chip ADC or an external ADC chip.

The beneficial effects of the above-mentioned technical solutions provided by the embodiments of the present invention at least include:

An array piezoelectric sensor signal processing circuit provided in an embodiment of the present invention includes: a main board; a microcontroller is arranged on the main board, and a first analog switch connected to the microcontroller; the first analog switch is connected with a first charge Amplifying circuit; the first charge amplifying circuit is composed of a plurality of charge amplifiers; the first charge amplifying circuit is connected with the piezoelectric sensor array for collecting piezoelectric sensor signals; the microcontroller sends an address signal to the first analog switch; the first The analog switch selects the signal channel of the piezoelectric sensor to be read according to the address signal, and collects the first analog signal; the microcontroller receives the first analog signal and processes the first analog signal. The signal acquisition of the piezoelectric sensor array can be performed more accurately.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is a frame diagram 1 of an array piezoelectric sensor signal processing circuit system provided by an embodiment of the present invention;

Fig. 2 is the microcontroller working flowchart that the embodiment of the present invention provides;

FIG. 3 is a schematic diagram of a charge amplifier provided by an embodiment of the present invention;

FIG. 4 is the second frame diagram of the signal processing circuit system of the arrayed piezoelectric sensor provided by the embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided for more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

An embodiment of the present invention provides an array piezoelectric sensor signal processing circuit, as shown in FIG. 1 , including: a main board;

A microcontroller is provided on the motherboard, and a first analog switch connected with the microcontroller;

The first analog switch is connected with a first charge amplifying circuit; the first charge amplifying circuit is composed of a plurality of charge amplifiers; the first charge amplifying circuit is connected with the piezoelectric sensor array for collecting piezoelectric sensor signals;

The microcontroller sends an address signal to the first analog switch; the first analog switch selects the signal channel of the piezoelectric sensor to be read according to the address signal, and collects the first analog signal; the microcontroller receives the first analog signal and converts the first analog signal to process.

The array piezoelectric sensor signal processing circuit provided in this embodiment can flexibly deal with piezoelectric sensor arrays of different scales, and collect signals from piezoelectric sensor arrays of different scales, and has the advantages of small footprint and scalability.

Specifically, as shown in FIG. 1 , a microcontroller (MCU may be used), a first charge amplification circuit, a first analog switch, an interface circuit, a sending circuit and a power supply circuit are arranged on the motherboard. The expansion board connected with the main board is provided with a second charge amplification circuit, a second analog switch and an enabling port of the expansion board. An analog-to-digital converter (ADC) is provided inside the microcontroller to convert the acquired analog signal into a digital signal.

The output signal of the first charge amplification circuit connected to the piezoelectric sensor array is connected to the first analog switch, the first analog switch selects the signal channel to be read according to the address signal sent by the microcontroller, collects and generates the first analog signal, and the The first analog signal is transmitted to the microcontroller. Among them, the output signal is the piezoelectric signal of the sensor. The charge amplification circuit is used to convert the weak charge signal of the piezoelectric sensor into a voltage signal with a higher signal-to-noise ratio that can be converted by the ADC. The microcontroller sends the address signal to the analog switch, and the analog signal sent by the analog switch to the microcontroller is two different lines. The address signal is directly output from the port of the microcontroller; after the analog signal enters the microcontroller from the port, it needs After ADC processing, it becomes a digital signal through digital-to-analog conversion.

On the expansion board, the output signal of the second charge amplification circuit connected to the piezoelectric sensor array is connected to the second analog switch, and the second analog switch selects the signal channel to be read according to the address signal sent by the microcontroller, and collects and generates the second analog switch. signal, and the second analog signal is transmitted to the microcontroller.

Further, the interface circuit is provided with a third analog switch, which is respectively connected to the microcontroller and the enable port of the expansion board. Similar to the above description, the third analog switch receives the address signal sent by the microcontroller to select the signal channel to be read, collects and generates a third analog signal, and transmits the third analog signal to the microcontroller.

A pull-down resistor is provided at the input port connecting the microcontroller to the interface circuit, so when the expansion board is not connected, the input port is stable at low level. The expansion board enable port is directly connected to the positive power supply network on the expansion board. When the expansion board is inserted into the main board, the power supply network driven by the power supply circuit (battery) on the main board is connected to the passive power supply network on the expansion board, and the level of the input port is pulled up to a high level, and the microcontroller will get high power. flat signal. The third analog switch on the main board will poll the level signals of the enable ports of all expansion boards, so as to obtain the number and position of the expansion boards connected and initialize them.

Several input signals from the expansion board are connected to the third analog switch. When the main board is first powered on, the microcontroller outputs the scanning address signal of the expansion board to let the third analog switch select the signal to be read. If the address corresponds to If the signal (the third analog signal) is high level, there is an expansion board on the interface at this address, and the ADC channel corresponding to the address is initialized, and the corresponding ADC channel is not initialized without the address of the expansion board, so as to reduce The power consumption of the circuit reduces the execution cycle of the program.

Specifically, after startup, first poll the number and address of the high-level signal of the enable port of the expansion board, and initialize the corresponding ADC channel; after that, the MCU sends an address signal of 0x00, and the channel 0 of the analog switch on the main board and the expansion board Connected to the common output terminal, the piezoelectric sensor signal connected to channel 0 in the piezoelectric sensor is amplified by the charge amplifier, and then transmitted to the MCU through the analog switch, and the ADC inside the MCU converts the analog signal into a digital signal and reads it simultaneously in sequence The first piezoelectric signal on the main board and expansion board is stored in the on-chip RAM memory (random access memory) or external ROM memory (read-only memory).

After reading, the address signal is incremented to 0x01, the channel 1 of the analog switch is connected to the common output terminal, and the MCU reads and stores the piezoelectric signal of this channel until the address is incremented to 0x07; The electrical signal is packaged into a data frame and sent to the terminal through the sending circuit; the address signal is reset to 0x00, and the next round of signal reading starts. If the analog switch has 16 channels, the address increments to 0x0F and back to zero, and so on.

Referring to Figure 2, the workflow of the microcontroller on the motherboard is: initializing the system clock, initializing the input and output port GPIO, and the serial port USART. Afterwards, the microcontroller outputs an increasing address to the analog switch (the third analog switch) in the interface circuit, and after polling all interfaces, initializes the ADC channel corresponding to the interface existing on the expansion board. Afterwards, the program enters the main loop, and outputs an increasing address signal to the analog switch (the first analog switch) connected to the charge amplification circuit, and this address signal will also be transmitted to the analog switch (the second analog switch) in the expansion board. After the ADC reads the voltage signal of this address, it increases the address and continues to read, that is, reads the next column of sensor signals, and the read value is stored in the internal or external memory. After reading the entire sensor array, the microcontroller packs all the stored data into a frame, wirelessly sends it to the host computer through the sending circuit, and starts the next cycle.

Among them, the analog switch (the third analog switch) in the interface circuit is used to judge the number and position of the expansion board connected, and the remaining analog switches (the first analog switch and the second module switch) are connected to the charge amplifier, so that the ADC of one channel can Read multiple analog signals.

Optionally, an on-chip ADC of a microcontroller such as STM32 or an external ADC chip is used to convert the output analog signal of the charge amplification circuit into a digital signal.

Optionally, the first analog switch, the second module switch and the third analog switch may use a CD4051 analog switch chip.

Optionally, the main board sends the piezoelectric sensor data matrix (one frame of data frame) to the computer host computer for processing through the Bluetooth module HC-05.

Optionally, both the expansion board and the main board are equipped with indicator lights, which are used to prompt whether the expansion board has been connected.

Optionally, the power supply circuit on the main board uses a lithium battery or an external power supply to rectify and supply power to the entire circuit.

Specifically, referring to FIG. 3 , it is a schematic diagram of the charge amplifier in the charge amplifier circuit (the first charge amplifier circuit and the second charge amplifier circuit). Among them, in addition to the capacitor (C5) connected to the negative input terminal and output terminal of the amplifier, the charge amplification circuit also has a capacitor (C1) connected in series with the negative input terminal for isolating DC signals; capacitor C1 and capacitor C5 are used for isolating high-frequency interference. R9 is the feedback resistor, which together with R5 determines the circuit gain. The left side of the circuit is the input terminal of the piezoelectric sensor signal, and the right side is the amplified signal.

The array piezoelectric sensor signal processing circuit provided in this embodiment can use the charge amplifier on the main board to process the signal for a small number of piezoelectric sensor arrays. As shown in Figure 1, after the signals of several piezoelectric sensors are connected to the corresponding charge amplifier on the main board, the microcontroller outputs the corresponding address signal to the analog switch to select the sensor signal to be read. The analog signal selected by the analog switch is converted into a digital signal by the on-chip ADC of the microcontroller, and then transmitted to the sending circuit on the main board through the on-chip serial port, and wirelessly sent to the host computer for processing.

Referring to Figure 4, for a large number of piezoelectric sensor arrays with a large scale, several expansion boards can be connected to the main board to realize signal reading, and the number of channels that can be read by each expansion board is determined by the circuit. The number of channels of the analog switch is determined, and the same circuit is used to reduce the design cost and manufacturing cost. Similarly, after the signal output by the piezoelectric sensor is connected to the charge amplifier and selected by the analog switch, it is converted into a digital signal by the on-chip ADC connected to the microcontroller on the main board.

Wherein, the address signal of the analog switch and the address signal of the main board are the same signal. The expansion board does not have its own power supply, its power network is connected to the main board, and the power supply is provided by the main board. When the scale of the piezoelectric sensor array is large, multiple expansion boards can be used to distribute a large number of charge amplifiers, and multiple expansion boards can be stacked to reduce the occupied space and the area of the circuit board.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies thereof, the present invention also intends to include these modifications and variations.

Claims (9)

1. An array piezoelectric sensor signal processing circuit, comprising: a main board;

the main board is provided with a microcontroller and a first analog switch connected with the microcontroller;

the first analog switch is connected with a first charge amplifying circuit; the first charge amplification circuit is composed of a plurality of charge amplifiers; the first charge amplifying circuit is connected with the piezoelectric sensor array and used for acquiring signals of the piezoelectric sensor;

the microcontroller sends an address signal to the first analog switch; the first analog switch selects a piezoelectric sensor signal channel to be read according to the address signal and acquires a first analog signal; the microcontroller receives the first analog signal and processes the first analog signal.

2. The array piezoelectric sensor signal processing circuit of claim 1, further comprising: an expansion board;

the expansion board is provided with a second charge amplification circuit and a second analog switch connected with the second charge amplification circuit; the second charge amplifying circuit is composed of a plurality of charge amplifiers;

the second analog switch is connected with the microcontroller; the second charge amplifying circuit is connected with the piezoelectric sensor array and used for collecting signals of the piezoelectric sensor;

the microcontroller sends an address signal to the second analog switch; and the second analog switch selects a piezoelectric sensor signal channel to be read according to the address signal, acquires a second analog signal and sends the second analog signal to the microcontroller.

3. The signal processing circuit of an array piezoelectric sensor of claim 2, wherein the expansion board further comprises an expansion board enable port; the expansion board enabling port is connected with a power network of the expansion board;

the mainboard is also provided with an interface circuit; a third analog switch is arranged in the interface circuit;

the third analog switch is respectively connected with the expansion board enabling port and the microcontroller;

the microcontroller sends an address signal to the third analog switch; the third analog switch selects a piezoelectric sensor signal channel to be read according to the address signal, collects a third analog signal and sends the third analog signal to the microcontroller;

and the microcontroller acquires the number and the positions of the expansion boards connected to the main board according to the third analog signal.

4. The signal processing circuit of claim 3, wherein a power circuit is disposed on the main board for supplying power to the main board and the expansion board.

5. The signal processing circuit of an array piezoelectric sensor according to claim 4, wherein the input port of the microcontroller connected to the interface circuit is provided with a pull-down resistor;

when the main board is connected with the expansion board, the power circuit is connected with a power network of the expansion board through the expansion board enabling port; the level of an input port connected with the interface circuit is changed from low level to high level through the pull-down resistor;

and the microcontroller acquires the number and the positions of the expansion boards connected to the main board according to the acquired level of the third analog signal.

6. The signal processing circuit of an array piezoelectric sensor of claim 1, wherein the microcontroller is configured with an analog-to-digital converter therein for converting the acquired analog signal into a digital signal.

7. The signal processing circuit of an array piezoelectric sensor as claimed in claim 6, wherein the motherboard further comprises a transmitting circuit for wirelessly transmitting the digital signal to a terminal.

8. The array-type piezoelectric sensor signal processing circuit of claim 7, wherein a serial port is further arranged inside the microcontroller; and the microcontroller transmits the digital signal to the sending circuit through the serial port.

9. The signal processing circuit of claim 6, wherein the ADC is an on-chip ADC or an external ADC chip.

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