Sensor interface circuit based on frequency modulation and sensor signal transmission method

Abstract

The invention discloses a sensor interface circuit based on frequency modulation and a sensor signal transmission method. A sensor analog signal generation circuit is used for outputting a first analog signal to a first conversion module; the first conversion module is used for converting the first analog signal into a digital signal and transmitting the digital signal to the first control module; the first control module is used for converting the digital signal into a pulse square wave signal and transmitting the pulse square wave signal to the frequency modulation circuit; the frequency modulation circuit is used for converting the pulse square wave signal into a frequency waveform signal and transmitting the frequency waveform signal to the frequency demodulation circuit; the frequency demodulation circuit is used for demodulating the frequency waveform signal into a pulse square wave signal and transmitting the pulse square wave signal to the second control module; and the second control module analyzes and processes the pulse square wave signal to generate sensor signal value data. The sensor interface circuit provided by the invention not only can transmit analog signals, but also can be compatible with a digital serial signal transmission function.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a sensor interface circuit and a sensor signal transmission method based on frequency modulation. Background Art

[0002] There are many types of sensor signal output interfaces, which can be divided into analog signal output interfaces and digital signal output interfaces based on the signal type. The analog voltage output interface is a commonly used interface for traditional sensors, which converts the measured physical quantity into a voltage signal output. The host connected to the sensor generally needs to perform analog-to-digital conversion on the analog signal before data processing. Since analog signals are easily interfered with, the new intelligent sensors now solve this problem by first performing analog-to-digital conversion on the original analog signal inside the sensor, converting the measured physical quantity into a digital signal, and then directly outputting it to the outside through the serial port of digital communication.

[0003] The physical output interface of traditional sensor analog voltage signals is generally a three-wire system, including signal lines and power ground lines; smart sensors are generally four-wire systems, and in addition to power and ground lines, the serial communication interface includes receiving lines and transmitting lines. Due to the different interface types, the physical interfaces of the two types of sensors are generally incompatible. If you need to support both analog and digital signal outputs, a total of five-wire physical interfaces are required, which will not only take up more physical space, but also bring problems such as physical interface compatibility. Summary of the invention

[0004] The present invention provides a sensor interface circuit and a sensor signal transmission method based on frequency modulation. By respectively adding a frequency modulation circuit and a frequency demodulation circuit of a digital signal to the output end and the receiving end of the original analog signal, the function of compatible digital serial signal transmission is achieved while keeping the physical output interface of the traditional sensor analog voltage signal unchanged.

[0005] According to a first aspect of the present invention, a sensor interface circuit based on frequency modulation is provided, comprising: an output interface circuit and an input interface circuit; the output interface circuit comprises a sensor analog signal generating circuit, a first conversion module, a first control module and a frequency modulation circuit; the input interface circuit comprises a frequency demodulation circuit and a second control module; a first output end of the sensor analog signal generating circuit is connected to an input end of the first conversion module, and the sensor analog signal generating circuit is used to output a first analog signal to the first conversion module; an output end of the first conversion module is connected to an input end of the first control module, and the first conversion module is used to convert the first analog signal into a digital signal to the first control module;

[0006] The output end of the first control module is connected to the first end of the frequency modulation circuit, and the second end of the frequency modulation circuit is connected to the second output end of the sensor analog signal generating circuit. The first control module is used to convert the digital signal into a pulse square wave signal to the frequency modulation circuit; the frequency modulation circuit is used to convert the pulse square wave signal into a frequency waveform signal to the frequency demodulation circuit;

[0007] The output end of the frequency demodulation circuit is connected to the second control module, and the frequency demodulation circuit is used to demodulate the frequency waveform signal into the pulse square wave signal to the second control module; the second control module generates sensor signal value data based on the analysis and processing of the pulse square wave signal.

[0008] Optionally, the input interface circuit further includes a second conversion module, and the second output end of the sensor analog signal generating circuit outputs a second analog signal to the second conversion module, and the second conversion module converts the second analog signal into a digital signal to the second control module.

[0009] Optionally, the frequency modulation circuit includes a first resistor, a second resistor and a first capacitor;

[0010] A first end of the first resistor is connected to an output end of the first control module, and a second end of the first resistor is connected to a first end of the second resistor;

[0011] The first end of the second resistor is connected to the second end of the first capacitor, and the second end of the second resistor is grounded;

[0012] The first end of the first capacitor is connected to the second output end of the sensor analog signal generating circuit, and the second end of the first capacitor is connected to the first end of the second resistor.

[0013] Optionally, the input interface circuit includes a third resistor, a fourth resistor and a first comparator;

[0014] A first end of the third resistor is connected to the negative electrode of the first comparator, and a second end of the third resistor is grounded;

[0015] A first end of the fourth resistor is connected to the first power supply end, and a second end of the fourth resistor is connected to the negative electrode of the first comparator;

[0016] The positive electrode of the first comparator is connected to the output end of the output interface circuit, and the output end of the first comparator is connected to the second control module.

[0017] Optionally, the fourth terminal of the first comparator is connected to the second power supply terminal, and the fifth terminal of the first comparator is grounded.

[0018] Optionally, the signal encoding method of the frequency modulation circuit and the frequency demodulation circuit includes single-frequency and dual-frequency frequency modulation encoding.

[0019] Optionally, the first conversion module and the second conversion module include analog-to-digital converters.

[0020] Optionally, the first control module and the second control module include a microcontroller.

[0021] According to a second aspect of the present invention, a method for transmitting a sensor signal is provided, which is performed by any frequency modulation-based sensor interface circuit in the first aspect of the present invention, and the transmission method comprises:

[0022] Obtaining an output signal of a sensor analog signal generating circuit;

[0023] Determining a transmission path of the output signal according to the output signal;

[0024] The output signal is transmitted according to the transmission path and sensor signal value data is determined.

[0025] Optionally, determining a transmission path of the output signal according to the output signal includes:

[0026] When the output signal is a second analog signal, the second conversion module converts the second analog signal into a digital signal and transmits it to the second control module;

[0027] When the output signal is a first analog signal, the first conversion module converts the first analog signal into a digital signal and transmits it to the first control module; the first control module converts the digital signal into a pulse square wave signal and transmits it to a frequency modulation circuit; the frequency modulation circuit converts the pulse square wave signal into a frequency waveform signal and transmits it to a frequency demodulation circuit; the frequency demodulation circuit demodulates the frequency waveform signal into the pulse square wave signal and transmits it to the second control module.

[0028] The present invention discloses a sensor interface circuit based on frequency modulation, comprising: an output interface circuit and an input interface circuit; the output interface circuit comprises a sensor analog signal generating circuit, a first conversion module, a first control module and a frequency modulation circuit; the input interface circuit comprises a frequency demodulation circuit and a second control module; the first output end of the sensor analog signal generating circuit is connected to the input end of the first conversion module, and the sensor analog signal generating circuit is used to output the first analog signal to the first conversion module; the output end of the first conversion module is connected to the input end of the first control module, and the first conversion module is used to convert the first analog signal into a digital signal to the first control module; the output end of the first control module is connected to the first end of the frequency modulation circuit, and the second end of the frequency modulation circuit is connected to the second output end of the sensor analog signal generating circuit, and the first control module is used to convert the digital signal into a pulse square wave signal to the frequency modulation circuit; the frequency modulation circuit is used to convert the pulse square wave signal into a frequency waveform signal to the frequency demodulation circuit; the output end of the frequency demodulation circuit is connected to the second control module, and the frequency demodulation circuit is used to demodulate the frequency waveform signal into a pulse square wave signal to the second control module; the second control module generates sensor signal value data based on the analysis and processing of the pulse square wave signal. The present invention provides a sensor interface circuit and a sensor signal transmission method based on frequency modulation. By respectively adding a frequency modulation circuit and a frequency demodulation circuit of a digital signal to the output end and the receiving end of the original analog signal, the function of compatible digital serial signal transmission is achieved while keeping the physical output interface of the traditional sensor analog voltage signal unchanged.

[0029] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 It is a schematic diagram of a sensor interface circuit in the prior art;

[0032] Figure 2 is a schematic diagram of a sensor interface circuit based on frequency modulation provided by an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of single-frequency and dual-frequency frequency modulation coding provided by an embodiment of the present invention;

[0034] Figure 4 It is a schematic diagram of frequency modulation waveform of a frequency modulation circuit provided by an embodiment of the present invention;

[0035] Figure 5 is a schematic diagram of a frequency modulation circuit provided by an embodiment of the present invention;

[0036] Figure 6 is a schematic diagram of a frequency demodulation circuit provided by an embodiment of the present invention;

[0037] Figure 7 is a flow chart of a sensor signal transmission method provided by an embodiment of the present invention;

[0038] Figure 8 This is a flow chart of another sensor signal transmission method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0041] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0042] Figure 1 This is a schematic diagram of the sensor interface circuit in the prior art, refer to Figure 1In the prior art, the sensor interface circuit includes an output interface circuit 10 and an input interface circuit 20. When the sensor transmits an analog signal, the sensor analog signal generating circuit 101 outputs the analog signal to the conversion module 201, and the conversion module 201 converts the analog signal into a digital signal and transmits it to the control module 202, which performs analysis and processing. However, if both analog and digital signal outputs are to be supported at the same time, a five-wire physical interface is required, which not only takes up more physical space, but also brings about the problem of physical interface compatibility.

[0043] Figure 2 is a schematic diagram of a sensor interface circuit based on frequency modulation provided by an embodiment of the present invention, with reference to Figure 2 The frequency modulation-based sensor interface circuit provided by the embodiment of the present invention includes: an output interface circuit 1 and an input interface circuit 2; the output interface circuit 1 includes a sensor analog signal generating circuit 11, a first conversion module 12, a first control module 13 and a frequency modulation circuit 14; the input interface circuit 2 includes a frequency demodulation circuit 21 and a second control module 22; the first output end of the sensor analog signal generating circuit 11 is connected to the input end of the first conversion module 12, and the sensor analog signal generating circuit 11 is used to output the first analog signal to the first conversion module 12; the output end of the first conversion module 12 is connected to the input end of the first control module 13, and the first conversion module 13 is used to convert the first analog signal into a digital signal to the first control module 13; the output end of the first control module 13 is connected to the first end of the frequency modulation circuit 14, and the second end of the frequency modulation circuit 14 is connected to the second output end of the sensor analog signal generating circuit 11, and the first control module 13 is used to convert the digital signal into a pulse square wave signal to the frequency modulation circuit 14; the frequency modulation circuit 14 is used to convert the pulse square wave signal into a frequency waveform signal to the frequency demodulation circuit 21;

[0044] The output end of the frequency demodulation circuit 21 is connected to the second control module 22. The frequency demodulation circuit 21 is used to demodulate the frequency waveform signal into a pulse square wave signal to the second control module 22. The second control module 22 generates sensor signal value data based on the pulse square wave signal analysis and processing.

[0045] Optionally, the input interface circuit 2 further includes a second conversion module 23 , and the second output end of the sensor analog signal generating circuit 11 outputs the second analog signal to the second conversion module 23 , and the second conversion module 23 converts the second analog signal into a digital signal to the second control module 22 .

[0046] Among them, the main function of the sensor interface circuit is to convert the analog signals collected by the sensor (including but not limited to: temperature signals, voltage signals, humidity, light intensity, etc.) into digital signals for processing by computers, etc.

[0047] Specifically, the sensor interface circuit provided by the embodiment of the present invention includes an output interface circuit 1 and an input interface circuit 2. The sensor analog signal generating circuit 11 is used to generate an analog signal. When it is necessary to output the analog signal in a serial digital signal transmission mode, the sensor analog signal generating circuit 11 outputs a first analog signal to a first conversion module 12. The first conversion module 12 converts the first analog signal into a digital signal to a first control module 13. The first control module 13 converts the digital signal into a pulse square wave signal. The pulse square wave signal is a non-continuous but periodic signal. The first control module 13 transmits the pulse square wave signal to a frequency modulation circuit 14. The frequency modulation circuit 14 converts the pulse square wave signal into a frequency waveform signal and transmits it to a frequency demodulation circuit 21 in the input interface circuit 2. The frequency demodulation circuit 21 demodulates the frequency waveform signal into a pulse square wave signal and transmits it to a second control module 22. The second control module 22 analyzes and processes the pulse square wave signal to obtain corresponding sensor signal value data.

[0048] When the sensor analog generation circuit 11 outputs the second analog signal, that is, when it is necessary to output the analog signal in the form of an analog signal transmission, the first conversion module 12, the first control module 13, the frequency modulation circuit 14 and the frequency demodulation circuit 21 do not operate, but directly transmit the second analog signal to the second conversion module 23. The second conversion module 23 converts the analog signal into a digital signal to the second control module 22. The second control module 22 directly performs analysis and processing based on the digital signal to obtain the sensor signal value data.

[0049] It can be seen from this that the sensor interface circuit based on frequency modulation provided in the embodiment of the present invention not only retains the function of the sensor analog signal output interface circuit in the prior art to output analog signals, and performs analog-to-digital conversion in the input interface circuit so that the signals are directly received by the host for analysis and processing, but also realizes the function of serial digital signal transmission. The function of serial digital signal transmission is realized while retaining the physical interface of the interface circuit of the prior art unchanged.

[0050] Optionally, the first conversion module 12 and the second conversion module 23 include analog-to-digital converters.

[0051] Specifically, an analog-to-digital converter is a device that converts a continuous analog signal into a digital signal.

[0052] Optionally, the signal encoding method of the frequency modulation circuit 14 and the frequency demodulation circuit 21 includes single-frequency and dual-frequency frequency modulation encoding.

[0053] Figure 3 is a schematic diagram of single and double frequency modulation coding provided by an embodiment of the present invention, refer to Figure 3Frequency Modulation, Two Frequency (F2F) is an improved FM coding method. In this method, the same pulse width is used to represent bit 0 and bit 1, but there is no level change in the middle of bit 0, and there is a level change process in the middle of bit 1. The schematic diagram of the F2F coding waveform is shown in Figure 3 As shown. Such characteristic square wave digital signal is suitable for modulation into the frequency waveform of analog signal and superimposed on DC level for transmission.

[0054] Figure 4 is a schematic diagram of a frequency modulation waveform of a frequency modulation circuit provided by an embodiment of the present invention, with reference to Figure 3 and Figure 4 Based on the above sensor interface circuit, the first control module converts the sensor analog signal into a digital signal after sampling by the first conversion module at the sending end, and performs F2F encoding on it according to the established communication protocol, and then sends a pulse square wave signal to the frequency modulation circuit through the input / output (IO) port. After passing through the frequency modulation circuit, it is coupled to the analog DC voltage signal and becomes as follows: Figure 4 The FM waveform shown in Figure 1 can be restored to the FM waveform after passing through the host receiving end frequency demodulation circuit. Figure 3 The pulse square wave signal shown is received by the IO port of the second control module and parsed into sensor data according to the established communication protocol. Therefore, based on the above sensor interface circuit, such F2F frequency modulation encoding method is adopted, and a proprietary communication protocol is established to realize the transmission of digital signals including sensor data.

[0055] Figure 5 is a schematic diagram of a frequency modulation circuit provided by an embodiment of the present invention, refer to Figure 5 Optionally, the frequency modulation circuit 14 includes a first resistor R1, a second resistor R2 and a first capacitor C1; the first end of the first resistor R1 is connected to the output end of the first control module 13, and the second end of the first resistor R1 is connected to the first end of the second resistor R2; the first end of the second resistor R2 is connected to the second end of the first capacitor C1, and the second end of the second resistor R2 is grounded; the first end of the first capacitor C1 is connected to the second output end of the sensor analog signal generating circuit 11, and the second end of the first capacitor C1 is connected to the first end of the second resistor R2.

[0056] Specifically, in the embodiment of the present invention, it is assumed that the DC level voltage of the analog signal is half of the power supply voltage, that is, VCC / 2. Figure 5The RC circuit shown in (the first resistor R1 and the first capacitor C1) realizes the frequency modulation of the pulse square wave. The first capacitor C1 can isolate the DC level and couple the modulated frequency signal to the analog voltage output signal Output. Considering the commonly used serial communication baud rate from 1200bps to 11520bps, a single pulse is about 10us~1ms, and a capacitor of 1uF~100uF is more suitable. In this implementation, the first capacitor C1 selects 4.7uF. The selection of the first resistor R1 and the second resistor R2 can realize the adjustment of the amplitude of the modulation signal. In this embodiment, R1=R2=10kΩ, and the amplitude of the modulated waveform is designed according to VCC / 2. The specific settings can be designed according to the needs, and the embodiment of the present invention does not limit this.

[0057] Figure 6 is a schematic diagram of a frequency demodulation circuit provided by an embodiment of the present invention, with reference to Figure 6 Optionally, the input interface circuit 21 includes a third resistor R3, a fourth resistor R4 and a first comparator U1; the first end of the third resistor R3 is connected to the negative electrode of the first comparator U1, and the second end of the third resistor R3 is grounded; the first end of the fourth resistor R4 is connected to the first power supply end, and the second end of the fourth resistor R4 is connected to the negative electrode of the first comparator U1; the positive electrode of the first comparator U1 is connected to the output end of the output interface circuit, and the output end of the first comparator U1 is connected to the second control module.

[0058] Specifically, in the frequency demodulation circuit 21, the frequency signal is demodulated by the first comparator U1. The third resistor R3 and the fourth resistor R4 are used as the reference of the first comparator U1, and can be selected with reference to the DC level of the analog voltage signal. In this embodiment, VCC / 2 is also considered, and the third resistor R3 = the fourth resistor R4 = 1MΩ is selected. A larger resistance value can reduce circuit power consumption.

[0059] As shown in the figure, the sensor signal input to the positive electrode of the first comparator U1 will output a high level at the comparator output end when the waveform is greater than the reference voltage at the negative electrode, otherwise it will output a low level, thus restoring the frequency modulated signal originally coupled to the analog DC voltage into a pulse square wave signal and outputting it to the IO port of the second control module.

[0060] Optionally, the fourth terminal of the first comparator U1 is connected to the second power supply terminal, and the fifth terminal of the first comparator U1 is grounded.

[0061] Optional, reference Figure 1 , the first control module 13 and the second control module 22 include microcontrollers.

[0062] Specifically, the microcontroller is also called a single-chip microcomputer. The first control module 13 is mainly used to convert the digital signal transmitted by the first conversion module 12 into a pulse square wave signal according to single-frequency and double-frequency frequency modulation encoding; the second control module 22 is mainly used to analyze and process the pulse square wave signal to obtain the corresponding sensor signal value data.

[0063] Figure 7 is a flow chart of a sensor signal transmission method provided by an embodiment of the present invention, with reference to Figure 7 According to the same inventive concept, an embodiment of the present invention provides a method for transmitting a sensor signal, which is executed by a sensor interface circuit based on frequency modulation in any of the above-mentioned inventive embodiments, and the transmission method includes:

[0064] S1. Obtain the output signal of the sensor analog signal generating circuit.

[0065] Specifically, an output signal of the sensor analog signal generating circuit is obtained, and the output signal may be a first analog signal and a second analog signal.

[0066] S2. Determine a transmission path of the output signal according to the output signal.

[0067] Specifically, the transmission path of the output signal is determined according to the first analog signal and the second analog signal obtained in the above step S1. When the output signal is the first analog signal, the transmission path is to convert the first analog signal into a digital signal and transmit it to the first control module, which is then transmitted to the second control module by the frequency modulation circuit and the frequency demodulation circuit. The second control module analyzes and processes the digital signal to obtain the corresponding sensor signal value data.

[0068] S3. Transmit the output signal according to the transmission path and determine the sensor signal value data.

[0069] Specifically, according to the transmission path determined in the above step S2, the second control module analyzes and processes the signal value data of the sensor according to different transmission paths.

[0070] Based on the above-mentioned embodiments of the invention, the embodiments of the invention further refine the determination of the transmission path of the output signal according to the output signal. Figure 8 is a flow chart of another sensor signal transmission method provided by an embodiment of the present invention, refer to Figure 8 , the transmission method provided by the embodiment of the present invention includes:

[0071] S2201: When the output signal is a second analog signal, the second conversion module converts the second analog signal into a digital signal and transmits it to the second control module.

[0072] Specifically, when the output signal of the sensor analog signal generating circuit is a second analog signal, the second conversion module directly converts the second analog signal into a digital signal and transmits it to the second control module. The second control module analyzes and processes the digital signal to obtain corresponding sensor signal value data, which is a traditional transmission method.

[0073] S2202. When the output signal is a first analog signal, the first conversion module converts the first analog signal into a digital signal and sends it to the first control module; the first control module converts the digital signal into a pulse square wave signal and sends it to the frequency modulation circuit; the frequency modulation circuit converts the pulse square wave signal into a frequency waveform signal and sends it to the frequency demodulation circuit; the frequency demodulation circuit demodulates the frequency waveform signal into a pulse square wave signal and sends it to the second control module.

[0074] Specifically, when the output signal of the sensor analog signal generating circuit is a first analog signal, the first conversion module converts the first analog signal into a digital signal, the first control module converts the digital signal to generate a pulse square wave signal to the frequency modulation circuit, the frequency modulation circuit converts the pulse square wave signal into a frequency waveform signal to the frequency demodulation circuit, the frequency demodulation circuit demodulates the frequency waveform signal into a pulse square wave signal to the second control module, and the second control module analyzes and processes the pulse square wave signal to obtain the signal value data of the corresponding sensor.

[0075] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A sensor interface circuit based on frequency modulation, characterized in that: include: An output interface circuit and an input interface circuit; the output interface circuit includes a sensor analog signal generating circuit, a first conversion module, a first control module and a frequency modulation circuit; the input interface circuit includes a frequency demodulation circuit and a second control module; the first output end of the sensor analog signal generating circuit is connected to the input end of the first conversion module, and the sensor analog signal generating circuit is used to output a first analog signal to the first conversion module; The output end of the first conversion module is connected to the input end of the first control module, and the first conversion module is used to convert the first analog signal into a digital signal to the first control module; The output end of the first control module is connected to the first end of the frequency modulation circuit, and the second end of the frequency modulation circuit is connected to the second output end of the sensor analog signal generating circuit. The first control module is used to convert the digital signal into a pulse square wave signal to the frequency modulation circuit; the frequency modulation circuit is used to convert the pulse square wave signal into a frequency waveform signal to the frequency demodulation circuit; The output end of the frequency demodulation circuit is connected to the second control module, and the frequency demodulation circuit is used to demodulate the frequency waveform signal into the pulse square wave signal to the second control module; The second control module generates sensor signal value data based on analysis and processing of the pulse square wave signal.

2. The frequency modulation based sensor interface circuit according to claim 1, characterized in that: The input interface circuit also includes a second conversion module. The second output end of the sensor analog signal generating circuit outputs a second analog signal to the second conversion module. The second conversion module converts the second analog signal into a digital signal and sends it to the second control module.

3. The frequency modulation based sensor interface circuit according to claim 1, characterized in that: The frequency modulation circuit includes a first resistor, a second resistor and a first capacitor; A first end of the first resistor is connected to an output end of the first control module, and a second end of the first resistor is connected to a first end of the second resistor; The first end of the second resistor is connected to the second end of the first capacitor, and the second end of the second resistor is grounded; The first end of the first capacitor is connected to the second output end of the sensor analog signal generating circuit, and the second end of the first capacitor is connected to the first end of the second resistor.

4. The frequency modulation based sensor interface circuit according to claim 1, characterized in that: The input interface circuit includes a third resistor, a fourth resistor and a first comparator; A first end of the third resistor is connected to the negative electrode of the first comparator, and a second end of the third resistor is grounded; A first end of the fourth resistor is connected to the first power supply end, and a second end of the fourth resistor is connected to the negative electrode of the first comparator; The positive electrode of the first comparator is connected to the output end of the output interface circuit, and the output end of the first comparator is connected to the second control module.

5. The frequency modulation based sensor interface circuit according to claim 4, characterized in that: The fourth terminal of the first comparator is connected to the second power supply terminal, and the fifth terminal of the first comparator is grounded.

6. The frequency modulation based sensor interface circuit according to claim 1, characterized in that: The signal encoding method of the frequency modulation circuit and the frequency demodulation circuit includes single-frequency and double-frequency frequency modulation encoding.

7. The frequency modulation based sensor interface circuit according to claim 2, characterized in that: The first conversion module and the second conversion module include analog-to-digital converters.

8. The frequency modulation based sensor interface circuit according to claim 1, characterized in that: The first control module and the second control module include microcontrollers.

9. A method for transmitting a sensor signal, characterized in that: The transmission method is performed by the frequency modulation-based sensor interface circuit according to any one of claims 1 to 8, wherein the transmission method comprises: Obtaining an output signal of a sensor analog signal generating circuit; Determining a transmission path of the output signal according to the output signal; The output signal is transmitted according to the transmission path and sensor signal value data is determined.

10. The method for transmitting sensor signals according to claim 9, characterized in that: The step of determining a transmission path of the output signal according to the output signal comprises: When the output signal is a second analog signal, the second conversion module converts the second analog signal into a digital signal and transmits it to the second control module; When the output signal is a first analog signal, the first conversion module converts the first analog signal into a digital signal and transmits it to the first control module; the first control module converts the digital signal into a pulse square wave signal and transmits it to a frequency modulation circuit; the frequency modulation circuit converts the pulse square wave signal into a frequency waveform signal and transmits it to a frequency demodulation circuit; the frequency demodulation circuit demodulates the frequency waveform signal into the pulse square wave signal and transmits it to the second control module.

Images