Ultrasonic wave programmable digital modulation method with current limiting protection and excitation circuit

Abstract

The invention discloses an ultrasonic programmable digital modulation method with current-limiting protection and an excitation circuit. The circuit comprises an MCU microprocessor, a digital modulator, a signal receiving amplifier, an analog-to-digital converter, a programmable excitation control circuit, a transmit-receive change-over switch SW1 and a sampling impedance matching circuit connected with an ultrasonic sensor. The MCU microprocessor is used for receiving a sampling signal of the ultrasonic sensor and controlling the digital modulator to output an excitation signal; the programmable excitation control circuit comprises four field-effect tubes forming a full-bridge circuit, and a resistor R1 is connected in series with a power main loop to limit the maximum current and play a role in excitation current-limiting protection; the ultrasonic sensor and the sampling impedance matching circuit are connected and communicated with the signal receiving amplifier, the analog-to-digital converter and the MCU microprocessor through a pin 1 and a pin 3 of the SW1, and a sampling signal of the ultrasonic sensor is read by the MCU microprocessor through the signal receiving amplifier and the analog-to-digital converter.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic sensors, and in particular to an ultrasonic programmable digital modulation method and an excitation circuit with current limiting protection. Background Art

[0002] At present, ultrasonic metering technology, as an advanced metering method, has broad application prospects in smart water meters and smart gas meters. In recent years, with the rapid development of semiconductor technology, the innovation of intelligent instruments, and the popularization of energy conservation and environmental protection, the application and development of ultrasonic metering technology in the field of water, natural gas and other energy metering at home and abroad has attracted more and more attention.

[0003] Ultrasonic measurement technology is a method of measuring by using the propagation characteristics of ultrasonic waves in a medium. Compared with traditional mechanical measurement technology, ultrasonic measurement technology has a better range and higher measurement accuracy, and can easily realize temperature and pressure compensation. Ultrasonic sensors in ultrasonic measurement technology are the most critical devices. This semiconductor sensor usually consists of a pressure sensitive element and a signal processing unit. Since ultrasonic measurement technology belongs to pure electric small signal processing, it is easily disturbed by noise and causes signal distortion. At present, in China, where the service life and accuracy requirements are relatively high, imports are still mainly used. In addition, taking TDK ultrasonic sensors as an example, the price of a single sensor is ten times that of domestic products with the same parameter range, but the stability, measurement accuracy, and failure rate of domestic products are far inferior to imported products.

[0004] In order to improve the accuracy and stability of domestic ultrasonic sensors in ultrasonic metrology, it is crucial to excite, match impedance, process signals and detect ultrasonic sensors. Under the same calibration test conditions, ultrasonic sensors of the same batch often have output analog signal voltages that are too high or too low due to processing and assembly errors, which will lead to over-accuracy and fail to meet the user's normal accuracy requirements. The high defective rate of products also causes a waste of raw materials. Sensor parameters of different manufacturers are different, and the modulation and excitation of ultrasonic acquisition signals will directly affect the performance and quality of ultrasonic metrology products.

[0005] Most of the current ultrasonic sensors use direct analog output. It is difficult to ensure the accuracy of the output signal, impedance matching between input and output, and anti-interference performance with weak analog electrical signals. The signal energy output by the sensor is transmitted in one direction, and the excitation is a fixed level. When the excitation power output at the output end exceeds the tolerance, the deviation cannot be corrected in time, resulting in measurement accuracy that does not meet the requirements.

[0006] At present, the excitation voltage signals of ultrasonic sensors are all output by a single power supply, using one positive output line and one negative line, a total of two excitation lines, of which the negative line is the negative pole of the output and also serves as the GND line. Such a design is relatively simple, but the required excitation power needs to be larger. At the same time, the induced strain voltage sampling signals are all tiny signals, as low as a few microvolts. The signal loop is very susceptible to interference from external high and low frequency signals, resulting in inaccurate sampling signal detection. If a simple amplifier is used, the interference signal and the normal sampling signal are amplified at the same time. After the interference signal and the sampling signal are superimposed, they are not easy to be identified and filtered. At the same time, the current scheme does not have the digital conversion and power modulation control process of the excitation signal, and the echo distortion and distortion cannot be controlled and corrected, so the sampling signal cannot be effectively identified. In addition, when the excitation signal is overcurrent, the ultrasonic sensor is also easily damaged. Summary of the invention

[0007] The present invention provides an ultrasonic programmable digital modulation method and excitation circuit with current limiting protection. The scheme of the present invention will improve the accuracy of the sensor excitation circuit, improve the consistency and service life of the sensor, and improve the anti-interference performance of the circuit. At the same time, the digital modulation method only needs to use a microprocessor through software to achieve the adjustment of the amplitude, frequency, duty cycle, etc. of the excitation signal, current limiting protection, the circuit is simple and low-cost, and each modulation mode can be easily and quickly implemented. Ultrasonic sensors with different parameters from different manufacturers can be directly applied to the same system circuit, expanding the scope of application, thereby solving the defects and shortcomings of the above-mentioned current technology.

[0008] An ultrasonic programmable digital modulation and excitation circuit with current limiting protection, comprising an MCU microprocessor, a digital modulator, a signal receiving amplifier, an analog / digital converter, a programmable excitation control circuit, a transceiver switch SW1, and a sampling impedance matching circuit connected to an ultrasonic sensor;

[0009] The MCU microprocessor is used to receive the sampling signal of the ultrasonic sensor and control the digital modulator to output the excitation signal;

[0010] The digital modulator is used to output the excitation signal after pulse width and frequency modulation. The excitation signal is generated by the inverter U2 to generate two excitation signals A and B with complementary phases and alternate outputs;

[0011] The programmable excitation control circuit includes four field effect transistors Q1, Q2, Q3, and Q4 that form a full-bridge circuit. The power supply VCC is connected to the drains of Q1 and Q2 through a resistor R1; the source of Q1 is connected to the drain of Q3, and is connected to a sampling impedance matching circuit and an ultrasonic sensor; the source of Q2 is connected to the drain of Q4, and is connected to a sampling impedance matching circuit and an ultrasonic sensor; and the source of Q1 or Q2 is connected to the sampling impedance matching circuit and the ultrasonic sensor through pins 1 and 2 of SW1; the source of Q3 and Q4 is grounded; the input pin of the inverter U2 is connected to the gates of Q2 and Q4, and the output pin is connected to the gates of Q1 and Q3;

[0012] The ultrasonic sensor and the sampling impedance matching circuit are connected to the signal receiving amplifier, the analog / digital converter and the MCU microprocessor through the 1st and 3rd pins of SW1. The sampling signal of the ultrasonic sensor is read by the MCU microprocessor through the signal receiving amplifier and the analog / digital converter.

[0013] In some embodiments, the ultrasonic programmable digital modulation and excitation circuit with current limiting protection, the sampling impedance matching circuit may include a resistor R2 and a capacitor C1, the two ends of the resistor R2 are connected to the ultrasonic sensor, and one end of the resistor R2 is connected to pin 1 of SW1 through the capacitor C1, and the other end is connected to the source of Q2 or Q1.

[0014] In some embodiments, the ultrasonic programmable digital modulation and excitation circuit with current limiting protection, the programmable excitation control circuit may also include a field effect transistor Q5, the sources of Q3 and Q4 are connected to the drain of Q5, the source of Q5 is grounded, and the gate of Q5 is connected to the protection control signal VG port of the MCU microprocessor.

[0015] In some embodiments, the ultrasonic programmable digital modulation and excitation circuit with current limiting protection, the programmable excitation control circuit may also include an isolation transformer B1, the source of Q1 is connected to the 4th pin of the primary winding of B1, the source of Q2 is connected to the 3rd pin of the primary winding of B1, and the secondary winding of B1 is connected to the sampling impedance matching circuit and the ultrasonic sensor through the 1st and 2nd pins of SW1. Further, the sampling impedance matching circuit may include a resistor R2 and a capacitor C1, the two ends of the resistor R2 are connected to the ultrasonic sensor, and one end of the resistor R2 is connected to the 1st pin of SW1 through the capacitor C1, and the other end is connected to the 2nd pin of the secondary winding of B1; the 1st pin of the secondary winding of B1 is connected to the 2nd pin of SW1.

[0016] In some embodiments, the ultrasonic programmable digital modulation and excitation circuit with current limiting protection may also include external ports CN1 and CN2 connected to the MCU microprocessor. CN1 and CN2 use 4-core foolproof connectors, which are respectively used for connecting to the power supply / lithium battery and the external Internet of Things module.

[0017] The present invention also provides the application of the ultrasonic programmable digital modulation and excitation circuit with current limiting protection in ultrasonic sensor signal sampling and excitation.

[0018] The present invention also provides an ultrasonic programmable digital modulation and excitation method with current limiting protection, which adopts the ultrasonic programmable digital modulation and excitation circuit with current limiting protection.

[0019] The technical solution of the present invention adopts a programmable digital modulation and excitation circuit, which is simple in design and safe and reliable in circuit operation. The core circuit includes a digital modulator, a programmable excitation control circuit and a sampling impedance matching circuit. When the sampled signal is high or low, the correct logical function can be realized through the MCU software algorithm, the corresponding control signal can be output, and the appropriate excitation power value can be provided to keep the sensor output signal within the normal range. The digital signal modulator adopts a digital modulation signal, and its design advantage is that the design is flexible and efficient, and the modulation of any frequency, phase, pulse width and duty cycle can be realized through software, which greatly simplifies the hardware circuit implementation and reduces power consumption and cost.

[0020] The programmable excitation control circuit is designed with excitation pulse conversion, control output adjustment power switch Q5, power converter B1, and high-frequency filtering. The digital excitation pulse can be directly applied to the excitation signal of the ultrasonic sensor after power conversion through the switch tubes Q1, Q2, Q3, and Q4; the MCU microprocessor can easily adjust the output controller, and the system circuits with different system operating voltages have expanded the scope of application.

[0021] The signal matching network (sampling impedance matching circuit), capacitor C1 and resistor R2 can achieve impedance matching and isolation between input and output. When the input signal frequency reaches the resonance point, the impedance of the signal matching network is the minimum and the current reaches the maximum point. The calculation formula is f=1 / (2πRC).

[0022] The signal receiving and transmitting switch SW1 is switched by a high-speed electronic switch, so that the same ultrasonic sensor can be used for both excitation signal output and echo detection.

[0023] The signal receiving amplifier can independently detect the excitation signal output and is signal adaptive. No matter how the sampled signal fluctuates, it can be converted into a digital signal in real time through the analog / digital converter and read by the MCU microprocessor. When the sampled level signal is greater than the highest sampling threshold level set by the software, the excitation signal output can be quickly turned off to achieve overvoltage protection without the need for additional protection circuits.

[0024] The ultrasonic sensor excitation current limiting protection limits the maximum current through the resistor R1 connected in series in the power main circuit, thus playing the role of excitation current limiting protection.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This scheme adopts the digital modulation method, and only needs to use the microprocessor through software to adjust the amplitude, frequency, duty cycle, etc. of the excitation signal. The circuit is simple and the cost is low.

[0027] 2. The excitation and sampling detection of this solution have adaptive closed-loop control. The core is to use a programmable excitation method to suppress the access of interference signals and improve the anti-interference performance of the input control circuit.

[0028] 3. This scheme is designed with an excitation level conversion circuit, which can realize the conversion of the excitation level phase.

[0029] 4. This solution has high sampling accuracy, reliable and sensitive protection, and the signal is processed directly in the microprocessor without the need for peripheral protection circuits; the induced voltage signal has high accuracy and low static power consumption.

[0030] 5. This solution uses a high-speed transceiver switching switch to save the number of sensors and improve the transceiver efficiency.

[0031] 6. The sampling level conversion of this solution has high input impedance. The excitation control terminal of this solution adopts power transformer coupling, which does not lose the power of the excitation signal and conveniently realizes power excitation. The main circuit of the excitation signal has a current limiting function, which protects the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a principle block diagram of an ultrasonic programmable digital modulation and excitation circuit with current limiting protection.

[0033] Figure 2 The present invention is a schematic diagram of the structure and principle of an ultrasonic programmable digital modulation and excitation circuit with current limiting protection.

[0034] Figure 3 The present invention is a schematic diagram of the structure and principle of another ultrasonic programmable digital modulation and excitation circuit with current limiting protection. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0036] Example 1

[0037] See also Figure 1 , Figure 2An ultrasonic programmable digital modulation and excitation circuit with current limiting protection includes an MCU microprocessor, a digital modulator, a signal receiving amplifier, an analog / digital (A / D) converter, a programmable excitation control circuit, a transceiver switching switch SW1, and a sampling impedance matching circuit connected to an ultrasonic sensor.

[0038] The sampling impedance matching circuit includes a resistor R2 and a capacitor C1, and both ends of the resistor R2 are connected to the ultrasonic sensor. One end of the resistor R2 is connected to the 1st pin of SW1 through the capacitor C1. The 3rd pin of SW1 is connected to the signal receiving amplifier, the analog / digital converter and the MCU microprocessor. Through the connection between the 1st and 3rd pins of SW1, the sampling signal of the ultrasonic sensor is read by the MCU microprocessor through the signal receiving amplifier and the analog / digital converter.

[0039] The MCU microprocessor is used to receive the sampling signal of the ultrasonic sensor to control the digital modulator to output the excitation signal. The digital modulator is used to output the excitation signal after pulse width and frequency modulation. The excitation signal is generated by the inverter U2 to generate two phase-complementary and alternately output excitation signals A and B.

[0040] The programmable excitation control circuit includes four field effect transistors Q1, Q2, Q3, Q4, field effect transistor Q5 and isolation transformer B1 that form a full bridge circuit. The power supply VCC is connected to the drain of Q1 and Q2 through the resistor R1; the source of Q1 is connected to the drain of Q3 and connected to the 4th pin of the primary winding of B1; the source of Q2 is connected to the drain of Q4 and connected to the 3rd pin of the primary winding of B1; the source of Q3 and Q4 is connected to the drain of Q5, the source of Q5 is grounded, and the gate of Q5 is connected to the protection control signal VG port of the MCU microprocessor; the input pin of the inverter U2 is connected to the gate of Q2 and Q4, and the output pin is connected to the gate of Q1 and Q3. Pin 1 of the secondary winding of B1 is connected to pin 2 of SW1, and pin 2 of the secondary winding of B1 is connected to the other end of the resistor R2.

[0041] The ultrasonic programmable digital modulation and excitation circuit with current limiting protection also includes external ports CN1 and CN2 connected to the MCU microprocessor. CN1 and CN2 use 4-core foolproof connectors, which are used for connecting to the power supply / lithium battery and the external Internet of Things module respectively.

[0042] like Figure 1 As shown, the above-mentioned ultrasonic programmable digital modulation and excitation circuit with current limiting protection based on pressure acquisition includes an MCU microprocessor, a power supply circuit, a digital signal processing and digital modulator, a programmable excitation control circuit, current limiting protection, a transmit and receive switching switch, signal matching and amplification, an analog-to-digital conversion circuit, etc.

[0043] When the power is turned on, the MCU microprocessor sends an enable instruction to the digital signal processing unit DSP (Digital Signal Processor); after receiving the instruction, the digital signal processing unit DSP outputs the ultrasonic excitation signal through the digital signal modulator DSM (Delta-Sigma) according to the set software algorithm; the excitation signal is output to the power transformer (i.e., isolation transformer B1) after pulse conversion and amplitude modulation by the programmable power controller, and then output to the excitation end of the ultrasonic sensor after energy coupling and rectification by transformer B1; at this time, the receiving end of the ultrasonic sensor outputs the induced voltage under the action of external ultrasound, and the induced voltage is shaped and amplified by the signal processing circuit and the amplifier circuit to obtain the appropriate level voltage of the sampling signal; the sampling signal is then converted by A / D analog-to-digital conversion and output to the microprocessor. When the MCU detects that the sampled signal is higher than the calibration value, the MCU will automatically reduce the amplitude of the excitation signal through the programmable power controller, so that the ultrasonic sensor signal output is within the calibration accuracy range, realizing the adaptive closed-loop regulation control of excitation and sampling feedback; and vice versa. When the MCU detects that the output voltage value of the sampling signal exceeds the safety threshold and reaches the set protection working point through software logic judgment, the microprocessor will output a protection signal, directly shut down the power controller Q5, stop the excitation output, and complete the overvoltage protection.

[0044] like Figure 2 As shown, the ultrasonic programmable digital modulation and excitation circuit with current limiting protection includes an MCU processor, a digital signal processing and modulation unit, a programmable excitation control unit, a current limiting unit, an impedance matching and amplification circuit unit, and an analog-to-digital conversion unit to form an overall closed-loop adaptive control system for excitation output and acquisition input, ultimately achieving sampling detection accuracy and protection control of the ultrasonic sensor by the microprocessor.

[0045] When the power is turned on, U1 (MCU) issues a command, the digital signal processing unit starts working, and the digital modulator outputs an excitation signal after pulse width and frequency modulation; the transmit and receive switching switch S1 is in the sending state, and pins 1 and 2 are turned on; the excitation signal passes through the U2 inverter to generate two excitation signals A and B, with complementary phases and output alternately. In one waveform cycle, the output of path A is high and path B is low in the first half of the cycle, and the output of path B is high and path A is low in the second half of the cycle; the microprocessor sends a control signal to Q5 through the VG port, Q5 is turned on, and after current limiting by R1, the full-bridge circuit of Q1, Q2, Q3, and Q4 outputs the corresponding excitation signal to the input end of B1; in the first half of the cycle, the output of path A is high and path B is low, the switch tubes Q1 and Q4 are turned on, Q2 and Q3 are turned off, and the excitation voltage is applied to the primary of the power transformer B1. At this time, B1 Pin 4 is positive and pin 3 is negative; the secondary winding is coupled to obtain the corresponding excitation voltage output, pin 1 of B1 is positive and pin 2 is negative; capacitor C1 and resistor R2 achieve impedance matching, and the ultrasonic sensor obtains the excitation signal of the first half cycle; in the second half cycle, the output of path B is high level and path A is low level, the switch tubes Q2 and Q3 are turned on, Q1 and Q4 are turned off, and Q5 is turned on, and the output excitation voltage is applied to the primary winding of the power transformer B1. At this time, pin 4 of B1 is negative and pin 3 is positive; the secondary winding is coupled to obtain the excitation signal output, pin 1 of B1 is negative and pin 2 is positive, and the ultrasonic sensor obtains the excitation voltage signal of the second half cycle; because the ratio of the primary and secondary voltages of B1 is proportional to the number of turns of the two, the primary voltage Vp, the primary number of turns Np, the secondary voltage Vs, the secondary number of turns Ns, then Vs=(Ns / Np)Vp, and the coupling of the excitation voltage and the power amplification output are realized through the turns ratio.

[0046] When the ultrasonic sensor receives, the transceiver switch S1 is in the receiving state, and pins 1 and 3 are turned on. At this time, an induced voltage will be generated under the action of the standard sound wave; the induced voltage is received and amplified by the signal receiving amplifier U3, and then the output end of the U3 amplifier is sent to the A / D analog-to-digital converter to convert the sampled induced voltage into a digital signal, which is read by the microprocessor through the read-write port. When the MCU detects that the sampled signal is higher than the calibration value, the MCU will automatically reduce the excitation signal through the programmable power controller Q5 so that the ultrasonic sensor signal output is within the calibrated accuracy range; when the MCU detects that the sampled signal is lower than the calibration value, the MCU will automatically increase the excitation signal through the programmable power controller Q5 so that the ultrasonic sensor signal output is within the calibrated accuracy range, realizing the adaptive closed-loop regulation control of excitation and sampling feedback; when the MCU detects that the output voltage value of the sampled signal exceeds the safety threshold, other abnormal events, or reaches the set protection working point through software logic judgment, the microprocessor will output a protection signal, directly turn off the power controller Q5, stop the excitation output, and complete the abnormal braking protection function.

[0047] Example 2

[0048] See also Figure 1 , Figure 3 The ultrasonic programmable digital modulation and excitation circuit with current limiting protection in this embodiment is similar to that in Embodiment 1, except that the coupling transformer B1 and the switch tube Q5 are omitted, the source of Q1 is connected to pin 2 of SW1, the other end of the resistor R2 is connected to the source of Q2, and Q3 and Q4 are grounded.

[0049] The above-mentioned ultrasonic programmable digital modulation and excitation circuit with current limiting protection, the excitation signal output directly drives the sensor, and the received signal is input to the MCU microprocessor for signal processing through A / D conversion, and the signal conversion can also be realized. The protection capability of the sensor is worse than that of Example 1, and the excitation signal output braking function is missing, but the cost can be reduced.

[0050] In summary, the present invention has the following characteristics: high reliability of the current limiting circuit and improved product life; high sampling accuracy and adaptive control design; phase transformation of the excitation signal and programmable control circuit; control of the protection signal; good application expansibility; and good fool-proofing of the external port.

[0051] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An ultrasonic programmable digital modulation and excitation circuit with current limiting protection, characterized in that: It includes an MCU microprocessor, a digital modulator, a signal receiving amplifier, an analog / digital converter, a programmable excitation control circuit, a transceiver switch SW1, and a sampling impedance matching circuit connected to the ultrasonic sensor; The MCU microprocessor is used to receive the sampling signal of the ultrasonic sensor and control the digital modulator to output the excitation signal; The digital modulator is used to output the excitation signal after pulse width and frequency modulation. The excitation signal is generated by the inverter U2 to generate two excitation signals A and B with complementary phases and alternate outputs; The programmable excitation control circuit includes four field effect transistors Q1, Q2, Q3, and Q4 that form a full-bridge circuit. The power supply VCC is connected to the drains of Q1 and Q2 through a resistor R1; the source of Q1 is connected to the drain of Q3, and is connected to a sampling impedance matching circuit and an ultrasonic sensor; the source of Q2 is connected to the drain of Q4, and is connected to a sampling impedance matching circuit and an ultrasonic sensor; and the source of Q1 or Q2 is connected to the sampling impedance matching circuit and the ultrasonic sensor through pins 1 and 2 of SW1; the source of Q3 and Q4 is grounded; the input pin of the inverter U2 is connected to the gates of Q2 and Q4, and the output pin is connected to the gates of Q1 and Q3; The ultrasonic sensor and the sampling impedance matching circuit are connected to the signal receiving amplifier, the analog / digital converter and the MCU microprocessor through the 1st and 3rd pins of SW1. The sampling signal of the ultrasonic sensor is read by the MCU microprocessor through the signal receiving amplifier and the analog / digital converter.

2. The ultrasonic programmable digital modulation and excitation circuit with current limiting protection according to claim 1 is characterized in that: The sampling impedance matching circuit includes a resistor R2 and a capacitor C1. Both ends of the resistor R2 are connected to the ultrasonic sensor, and one end of the resistor R2 is connected to pin 1 of SW1 through the capacitor C1, and the other end is connected to the source of Q2 or Q1.

3. The ultrasonic programmable digital modulation and excitation circuit with current limiting protection according to claim 1 is characterized in that: The programmable excitation control circuit also includes a field effect transistor Q5, the sources of Q3 and Q4 are connected to the drain of Q5, the source of Q5 is grounded, and the gate of Q5 is connected to the protection control signal VG port of the MCU microprocessor.

4. The ultrasonic programmable digital modulation and excitation circuit with current limiting protection according to claim 1 or 3, characterized in that: The programmable excitation control circuit also includes an isolation transformer B1, the source of Q1 is connected to pin 4 of the primary winding of B1, the source of Q2 is connected to pin 3 of the primary winding of B1, and the secondary winding of B1 is connected to the sampling impedance matching circuit and the ultrasonic sensor through pins 1 and 2 of SW1.

5. The ultrasonic programmable digital modulation and excitation circuit with current limiting protection according to claim 4 is characterized in that: The sampling impedance matching circuit includes a resistor R2 and a capacitor C1, wherein both ends of the resistor R2 are connected to the ultrasonic sensor, and one end of the resistor R2 is connected to pin 1 of SW1 through the capacitor C1, and the other end is connected to pin 2 of the secondary winding of B1; pin 1 of the secondary winding of B1 is connected to pin 2 of SW1.

6. The ultrasonic programmable digital modulation and excitation circuit with current limiting protection according to claim 1, characterized in that: The ultrasonic programmable digital modulation and excitation circuit with current limiting protection also includes external ports CN1 and CN2 connected to the MCU microprocessor. CN1 and CN2 use 4-core foolproof connectors, which are respectively used for connecting to the power supply / lithium battery and the external Internet of Things module.

7. Application of the ultrasonic programmable digital modulation and excitation circuit with current limiting protection according to any one of claims 1 to 6 in ultrasonic sensor signal sampling and excitation.

8. An ultrasonic programmable digital modulation and excitation method with current limiting protection, characterized in that: An ultrasonic programmable digital modulation and excitation circuit with current limiting protection as described in any one of claims 1 to 6 is adopted.

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