Flow acquisition circuit based on analog switch and ultrasonic water meter
By controlling the flow acquisition circuit of the ultrasonic water meter with an analog switch, the problem of flow measurement data distortion caused by the switching delay of the button switch is solved, and low-latency, high-reliability flow detection is achieved.
Patent Information
- Application Number
- CN202423150329.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2034-12-19
AI Technical Summary
When the transducer in an existing ultrasonic water meter is switched by a push-button switch, a time delay occurs, which can cause the flow measurement data to be easily distorted.
A flow acquisition circuit based on analog switches is adopted. The main control chip controls the first or second analog switch to connect to the upstream and downstream transducers respectively, so as to achieve low-latency flow acquisition.
This reduces the latency of traffic detection, ensuring the reliability and accuracy of traffic collection results.
Smart Images
Figure CN223769578U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of ultrasonic water meter measurement, and in particular to a flow acquisition circuit based on an analog switch and an ultrasonic water meter. Background Technology
[0002] Currently, in the application of ultrasonic water meters for flow detection, a push-button switch is generally used to control the transducer to achieve flow detection. However, when the transducer is switched between channels by controlling it with a push-button switch, jitter occurs, resulting in a certain time delay, which makes the flow measurement data prone to distortion. Utility Model Content
[0003] The purpose of this invention is to provide a flow acquisition circuit based on an analog switch and an ultrasonic water meter, so as to alleviate the technical problem of easy distortion of flow measurement data in the prior art.
[0004] In a first aspect, embodiments of the present invention provide a flow acquisition circuit based on an analog switch, comprising:
[0005] A main control chip, an analog switch, and a transducer are connected in sequence; wherein, the analog switch includes a first analog switch and a second analog switch, and the first analog switch or the second analog switch is respectively connected to two transducer paths, each transducer path including an upstream transducer and a downstream transducer;
[0006] The main control chip, under preset conditions, controls the target transducer path to work through the first analog switch or the second analog switch;
[0007] The upstream and downstream transducers in the target transducer path transmit and receive ultrasonic waves via the first analog switch or the second analog switch to the main control chip, so that the main control chip can obtain the flow rate value.
[0008] In conjunction with the first aspect, this utility model embodiment provides a first possible implementation of the first aspect, wherein the main control chip sends a first control signal to the first analog switch or the second analog switch to enable the first analog switch or the second analog switch, as well as the upstream and downstream transducers in the target transducer path corresponding to the first analog switch or the second analog switch, and enter the working state.
[0009] In conjunction with the first aspect, this utility model embodiment provides a second possible implementation of the first aspect, which further includes a boost circuit; the boost circuit is connected to the main control chip and is used to boost the second control signal output by the main control chip.
[0010] In conjunction with the first aspect, this utility model embodiment provides a third possible implementation of the first aspect, wherein the boost circuit is connected to the first analog switch or the second analog switch, and is used to send the boosted second control signal to the first analog switch or the second analog switch to drive the upstream or downstream transducer in the target transducer path corresponding to the first analog switch or the second analog switch to emit ultrasonic waves.
[0011] In conjunction with the first aspect, this utility model embodiment provides a fourth possible implementation of the first aspect, which further includes a first low-power module connected to the main control chip and the first analog switch respectively; the first low-power module includes a first latch and a first field-effect transistor;
[0012] The main control chip sends the output first level signal to the first latch to control the on / off state of the first field-effect transistor, and the enable and working states of the first analog switch and the upstream and downstream transducers in the target transducer path corresponding to the first analog switch.
[0013] In conjunction with the first aspect, this utility model embodiment provides a fifth possible implementation of the first aspect, wherein, when the preset conditions are not met, the main control chip outputs a high level, the first latch is in a low level state, controls the first field-effect transistor to turn off, and the first analog switch and the upstream and downstream transducers in the target transducer path corresponding to the first analog switch are in an disabled state and a non-working state.
[0014] Under preset conditions, the main control chip outputs a low level, the first latch is in a high level state, the first field-effect transistor is turned on, and the first analog switch and the upstream and downstream transducers in the target transducer path corresponding to the first analog switch are in an enabled state and an operating state.
[0015] In conjunction with the first aspect, this utility model embodiment provides a sixth possible implementation of the first aspect, which further includes a second low-power module connected to the main control chip and the second analog switch respectively; the second low-power module includes a second latch and a second field-effect transistor;
[0016] The main control chip sends the output second-level signal to the second latch to control the on / off state of the second field-effect transistor, the second analog switch, and the upstream and downstream transducers in the target transducer path corresponding to the second analog switch, as well as their enable and working states.
[0017] In conjunction with the first aspect, this utility model embodiment provides a seventh possible implementation of the first aspect, wherein, when the preset conditions are not met, the main control chip outputs a high level, the second latch is in a low level state, controls the second field-effect transistor to turn off, and the second analog switch and the upstream and downstream transducers in the target transducer path corresponding to the second analog switch are in an disabled state and a non-working state.
[0018] Under preset conditions, the main control chip outputs a low level, the second latch is in a high level state, the second field-effect transistor is turned on, and the second analog switch and the upstream and downstream transducers in the target transducer path corresponding to the second analog switch are in an enabled state and an operating state.
[0019] In conjunction with the first aspect, this utility model embodiment provides an eighth possible implementation of the first aspect, wherein the main control chip controls the target transducer path to operate when it receives a flow detection signal sent by a sensor or reaches a preset time period; wherein the preset condition is receiving a flow detection signal sent by a sensor or reaching a preset time period.
[0020] Secondly, this utility model embodiment also provides an ultrasonic water meter, including the flow acquisition circuit based on an analog switch as described above, and also includes a water meter body.
[0021] This utility model embodiment provides a flow acquisition circuit and an ultrasonic water meter based on analog switches. By using two analog switches, the main control chip controls the target transducer path and the target transducer in each transducer path, so as to achieve flow acquisition with low latency and thus ensure the reliability of the flow acquisition results.
[0022] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention are realized and obtained through the structures particularly pointed out in the description and the accompanying drawings.
[0023] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0024] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0025] Figure 1 A schematic diagram of a flow acquisition circuit based on an analog switch provided for an embodiment of this utility model;
[0026] Figure 2 A circuit diagram of a converter provided for an embodiment of this utility model;
[0027] Figure 3 A schematic diagram of a low-power branch circuit of a flow acquisition circuit based on an analog switch, provided for an embodiment of this utility model;
[0028] Figure 4 A schematic diagram of a low-power branch circuit of another flow acquisition circuit based on an analog switch provided for an embodiment of this utility model. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0030] Research has found that the time delay generated when switching transducers using a push-button switch can affect the reliability of flow detection.
[0031] Based on this, the present invention provides a flow acquisition circuit and an ultrasonic water meter based on an analog switch, which can ensure response speed and reduce delay time through the analog switch, thereby improving the technical problem of easy distortion of existing flow measurement data.
[0032] The following is a detailed description through examples.
[0033] This application provides a flow acquisition circuit based on an analog switch, including a main control chip, an analog switch, and a transducer connected in sequence; wherein, the analog switch includes a first analog switch and a second analog switch, and the first analog switch or the second analog switch is respectively connected to two transducer paths, each transducer path including an upstream transducer and a downstream transducer;
[0034] The main control chip controls the target transducer path to work through the first analog switch or the second analog switch when the preset conditions are met.
[0035] The upstream and downstream transducers in the target transducer path transmit and receive ultrasonic waves and send the flight time to the main control chip through the first analog switch or the second analog switch so that the main control chip can obtain the flow rate value.
[0036] In a preferred embodiment of practical application, two analog switches are used to enable the main control chip to control the target transducer path and target transducer in each transducer path, so as to achieve low latency in traffic acquisition and thus ensure the reliability of traffic acquisition results.
[0037] An analog switch is a device specifically designed for electronic switching, intended to conduct or isolate analog signals, including voltage and current signals, to support a variety of analog applications. It's important to note that analog switches differ from load switches, which can withstand larger currents due to their lower on-resistance. The primary function of an analog switch is time-division multiplexing when system interface resources are insufficient, providing a cost-effective solution. In four-channel ultrasonic water meters, analog switches are used to control signal transmission and switching, ensuring that ultrasonic signals from different channels can be measured effectively.
[0038] Figure 1 This is a schematic diagram of a flow acquisition circuit based on an analog switch, provided for an embodiment of the present invention.
[0039] Reference Figure 1 The main control chip, MSPFR6007, controls the target transducer path to operate when it receives a flow detection signal from the sensor or reaches a preset time period. The preset conditions are receiving a flow detection signal from the sensor or reaching a preset time period.
[0040] In practical applications, when the main control chip detects water flow through flow or pressure sensors, a preset condition is met. At this point, it sends a data acquisition signal to control the target transducer in the target transducer path to start emitting ultrasonic waves. The main control chip can also be set to periodically send data acquisition signals at set intervals to control the target transducer in the target transducer path to start emitting ultrasonic waves, thus ensuring regular flow measurement.
[0041] The acquisition signal can be sent from the CH0_OUT pin and CH1_OUT pin of the main control chip and transmitted to the EN terminal of the first analog switch U1 and the second analog switch U2 respectively, so as to control the analog switch, enable the target transducer and select the working mode.
[0042] For example, the operating mode can be selected (current or countercurrent mode), and the main control chip will send a corresponding acquisition signal to start the target transducer in the target transducer path to use ultrasonic signals for measurement.
[0043] For example, the main control chip sends a first control signal to the first analog switch or the second analog switch to enable the first analog switch or the second analog switch, as well as the upstream and downstream transducers in the target transducer path corresponding to the first analog switch or the second analog switch, and put them into working state.
[0044] The CH0_IN and CH1_IN pins are used to transmit data such as the time-of-flight of the target transducer back to the main control chip. The UP3 and DOWN3 pins, and the UP4 and DOWN4 pins of the analog switches are interfaces for connecting to the corresponding transducers. The first analog switch U1 has two UP3 pins and two DOWN3 pins, each connected to a different transducer. The mode selection signal on the EN pin triggers the corresponding pin to control the transducer's operation. If the UP3 pin is active, it means the first analog switch allows the upstream transducer to emit ultrasonic signals; if the DOWN3 pin is active, it means the first analog switch allows the downstream transducer to receive ultrasonic signals. Similarly, the UP4 and DOWN4 pins in the second analog switch U2 serve the same function.
[0045] Among them, such as Figure 2 As shown, a transducer path includes an upstream transducer UP3 and a downstream transducer DOWM3 located upstream and downstream of the current circuit, respectively. In practical applications, a four-channel ultrasonic water meter has four transducer paths, i.e., eight transducers. Two transducers on the same path are placed in opposite positions to transmit and receive ultrasonic signals. The time difference between receiving and transmitting ultrasonic signals is the time-of-flight difference, used to calculate the flow rate during this time period. The transducer's function is to transmit and receive ultrasonic signals, convert them into electrical signals, and then transmit them back to the first or second analog switch. The first or second analog switch then transmits the signals to the main control chip via the CH0_IN and CH1_IN pins to calculate the time-of-flight difference, thereby calculating the flow rate.
[0046] Based on the signals collected by the main control chip, the first analog switch or the second analog switch can be controlled to switch different transducer paths (channels), thereby enabling the selection of different channels.
[0047] The operating mode selection corresponding to the acquired signal is determined by the MCU based on the data type to be acquired. For example, if it is necessary to measure the downstream (upstream to downstream) speed, the main control chip may select the upstream transducer to transmit the signal and the downstream transducer to receive the signal; if it is necessary to measure the upstream (downstream to upstream) speed, the main control chip will reverse the operating mode selection corresponding to the acquired signal, activating the downstream transducer to transmit and the upstream transducer to receive, thus realizing the measurement of the forward and reverse flow rates.
[0048] 1. Downstream control:
[0049] In downstream mode, the upstream transducer (UP) emits ultrasonic signals, which propagate through the water flow to the downstream transducer (DOWN), where the echo signal is received. Signal acquisition enables channel selection and activates the upstream transducer (UP) as the transmitter and the downstream transducer (DOWN) as the receiver. The main control chip enables the upstream transducer to transmit signals and the downstream transducer to receive signals by controlling the enable terminal of either the first or second analog switch.
[0050] 2. Reverse flow control:
[0051] In counter-current mode, the downstream transducer (DOWN) emits an ultrasonic signal, which propagates against the water flow to the upstream transducer (UP), where it receives the echo signal. The main control chip selects the channel and switches to counter-current mode based on the acquired signal, activating the downstream transducer to emit the signal while the upstream transducer receives the echo signal. In this mode, the first or second analog switch selects the downstream transducer to emit and the upstream transducer to receive based on the operating mode corresponding to the acquired signal from the main control chip.
[0052] Specifically, the main control chip generates a sampling signal based on the target transducer path to be activated (e.g., UP and DOWN or UP3 and DOWN3), used for channel selection and enabling. Assuming a two-bit binary signal is used for control (e.g., 00, 01, 10, 11), each binary value corresponds to a different transducer path. For example, 00: selects UP1 and DOWN1, 01: selects UP2 and DOWN2, 10: selects UP3 and DOWN3, 10: selects UP4 and DOWN4, and so on.
[0053] This acquisition signal will enter the EN terminal of the analog switch through the CH0_OUT and CH1_OUT pins of the main control chip to transmit control logic to the analog switch.
[0054] Understandably, after receiving the acquisition signal, the enable terminal of the analog switch determines the current target transducer path: if the channel selection signal corresponding to this operating mode is 00, the analog switch selects the upstream transducer UP and the downstream transducer DOWN as the operating channels. If the channel selection signal corresponding to the operating mode is 01, the analog switch selects the upstream transducer UP3 and the downstream transducer DOWN3 as the operating channels, and so on. Under the control of the analog switch, the target transducer path can be switched to the corresponding target transducer (upstream or downstream) to control the transmission or reception of ultrasonic signals.
[0055] As an optional embodiment, a boost circuit is also included; the boost circuit is connected to the main control chip and is used to boost the second control signal output by the main control chip.
[0056] The CH0_OUT and CH1_OUT pins are connected to the boost circuit between the main control chip and each analog switch. This boost circuit can convert the 3V control signal output by the main control chip into a 5V control signal.
[0057] For example, the boost circuit is connected to the first analog switch or the second analog switch to send the boosted second control signal to the first analog switch or the second analog switch to drive the upstream or downstream transducer in the target transducer path corresponding to the first analog switch or the second analog switch to emit ultrasonic waves.
[0058] In some embodiments, such as Figure 3 As shown, it also includes a first low-power module that is connected to the main control chip and the first analog switch U1 respectively; the first low-power module includes a first latch U3 and a first field-effect transistor Q5;
[0059] The main control chip sends the first level signal to the first latch to control the on / off state of the first field-effect transistor, the first analog switch, and the upstream and downstream transducers in the target transducer path corresponding to the first analog switch, as well as their enable and working states.
[0060] like Figure 4 As shown, it also includes a second low-power module that is connected to the main control chip and the second analog switch U2 respectively; the second low-power module includes a second latch U4 and a second field-effect transistor Q6;
[0061] The main control chip sends the output second-level signal to the second latch to control the on / off state of the second field-effect transistor, the second analog switch, and the upstream and downstream transducers in the target transducer path corresponding to the second analog switch, as well as their enable and working states.
[0062] It should be noted that the circuit branch that implements the low-power function includes a latch, which stores the current level signal issued by the main control chip for selecting the working mode and enabling, ensuring signal stability and avoiding false triggering.
[0063] A latching mechanism is used to maintain the output signal state of the main control chip, allowing the chip to enter a low-power state while the signal remains unchanged. The latch controls the signal state. Working principle: When the main control chip outputs a control level signal, the latch holds this state and controls the MOSFET to turn on or off, thereby controlling the analog switch accordingly. Once the latch captures the preset target signal from the main control chip, the chip can stop outputting signals and enter a low-power mode, but the latch's output state remains unchanged. When a change in the control signal is needed, the main control chip outputs a signal again, and the latch latches the new control level signal, driving the MOSFET to switch to the analog switch state. When the control state remains unchanged, the main control chip does not need to continuously output signals, reducing power consumption.
[0064] In practical applications, if the preset conditions are not met, the main control chip outputs a high level, the first latch is in a low level state, the first field-effect transistor is turned off, and the first analog switch and the upstream and downstream transducers in the target transducer path corresponding to the first analog switch are in an disabled state and a non-working state.
[0065] Under the condition that the preset conditions are met, the main control chip outputs a low level, the first latch is in a high level state, the first field-effect transistor is turned on, and the first analog switch and the upstream and downstream transducers in the target transducer path corresponding to the first analog switch are in an enabled state and a working state.
[0066] If the preset conditions are not met, the main control chip outputs a high level, the second latch is in a low level state, the second field-effect transistor is turned off, and the second analog switch and the upstream and downstream transducers in the target transducer path corresponding to the second analog switch are in an disabled state and a non-working state.
[0067] Under preset conditions, the main control chip outputs a low level, the second latch is in a high level state, the second field-effect transistor is turned on, and the second analog switch and the upstream and downstream transducers in the target transducer path corresponding to the second analog switch are in an enabled state and a working state.
[0068] For example, for each circuit branch of the analog switch and low-power function, the acquisition signal output by the main control chip, i.e. the control level signal, sets the latch input state to control the power supply state of the analog switch and transducer.
[0069] During normal operation, the control level signal is set high when data acquisition is needed, and the latch outputs a high level to turn on the N-channel MOSFET, supplying power to the analog switch and transducer. In low-power mode, the latch outputs a low level, turning off the MOSFET and cutting off the power supply to save energy.
[0070] When no data is being acquired, the main control chip sets the control level signal to a high level, the latch maintains a low output level, the MOSFET is turned off, and the analog switch and transducer are disconnected from power. When data acquisition is required, the control level signal is low, causing the latch to output a high level, the MOSFET to turn on, and the chip enters normal operating mode.
[0071] The flow acquisition circuit based on analog switches provided in this application can receive analog voltage signals. The main control chip controls the on / off state of the first or second analog switch by outputting a control level signal. The combination of the main control chip and the analog switches involves the main control chip controlling the on / off state of the analog switches through the EN terminal. The analog switches transmit the data measured by the four transducers to the main control chip through the CH0_IN and CH1_IN pins and after passing through an RC filter circuit. The measurement data obtained in this way is smooth, has low latency, is simple, and efficient, reducing unnecessary additional circuitry. The low-power circuit branch introduced between the main control chip and the analog switches can reduce the output signal frequency of the main control chip while maintaining the state of the analog switches, thereby significantly reducing power consumption and saving costs.
[0072] In some embodiments, the present invention also provides an ultrasonic water meter, including the flow acquisition circuit based on an analog switch as described above, and a water meter body.
[0073] This flow acquisition circuit based on analog switches can achieve more accurate water flow detection.
[0074] The ultrasonic water meter provided in this embodiment of the present invention has the same technical features as the flow acquisition circuit based on analog switch provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.
[0075] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0076] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0077] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.
[0078] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0079] In addition, in the various embodiments of this utility model, each functional unit can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0080] Finally, it should be noted that the above-described embodiments are merely specific implementations of this utility model, used to illustrate the technical solutions of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model.
Claims
1. An analog switch based flow acquisition circuit, comprising: The application relates to a flowmeter, which comprises a master control chip, an analog switch and a transducer connected in sequence, wherein the analog switch comprises a first analog switch and a second analog switch, the first analog switch or the second analog switch is connected with two transduction paths respectively, each transduction path comprises an upstream transducer and a downstream transducer, the master control chip controls a target transducer path through the first analog switch or the second analog switch when a preset condition is met, the upstream transducer and the downstream transducer in the target transducer path send the time of flight of the transmitted ultrasonic wave to the master control chip through the first analog switch or the second analog switch, so that the master control chip obtains a flow value, the master control chip sends a first control signal to the first analog switch or the second analog switch, so that the first analog switch or the second analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the first analog switch or the second analog switch are enabled and enter a working state, the application further comprises a boost circuit connected with the master control chip, which is used for boosting a second control signal output by the master control chip, the boost circuit and the first analog switch or the second analog switch are connected, the second control signal after the boosting is sent to the first analog switch or the second analog switch, so as to drive the upstream transducer or the downstream transducer in the target transducer path corresponding to the first analog switch or the second analog switch to emit ultrasonic waves, the application further comprises a first low-power module connected with the master control chip and the first analog switch respectively, the first low-power module comprises a first latch and a first field effect transistor, the master control chip sends a first level signal output to the first latch, controls the on-off of the first field effect transistor, and enables and controls the working state of the first analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the first analog switch, the master control chip outputs a high level when the preset condition is not met, the first latch is in a low level state, the first field effect transistor is turned off, and the first analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the first analog switch are in a disabled state and an unworking state, the master control chip outputs a low level when the preset condition is met, the first latch is in a high level state, the first field effect transistor is turned on, and the first analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the first analog switch are in an enabled state and a working state, the application further comprises a second low-power module connected with the master control chip and the second analog switch respectively, the second low-power module comprises a second latch and a second field effect transistor, the master control chip sends a second level signal output to the second latch, controls the on-off of the second field effect transistor, and enables and controls the working state of the second analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the second analog switch. 2. The analog switch based flow acquisition circuit of claim 1, wherein, 3. The analog switch based flow acquisition circuit of claim 1, wherein, 4. The analog switch based flow acquisition circuit of claim 3, wherein, 5. The analog switch based flow acquisition circuit of claim 2, wherein, 6. The analog switch based flow acquisition circuit of claim 5, wherein, 7. The analog switch based flow acquisition circuit of claim 2, wherein, 8. The analog switch based flow acquisition circuit of claim 7, wherein, In the case that the preset condition is not met, the main control chip outputs high level, the second latch is in low level state, the second field effect transistor is controlled to be off, the second analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the second analog switch are in non-enabled state and non-working state; In the case that the preset condition is met, the main control chip outputs low level, the second latch is in high level state, the second field effect transistor is controlled to be on, the second analog switch and the upstream transducer and the downstream transducer in the target transducer path corresponding to the second analog switch are in enabled state and working state.
9. The analog switch based flow acquisition circuit of claim 1, wherein, The main control chip controls the target transducer path to work in the case that the flow detection signal sent by the sensor is received or a preset time period is reached.
10. An ultrasonic water meter characterized by, The analog switch-based flow acquisition circuit comprises a water meter main body.