1. A metering circuit, comprising: the comparison circuit, the filter circuit and the counting circuit are connected in sequence;

the comparison circuit comprises a comparison mode selection circuit and a comparator;

the comparison mode selection circuit comprises a reference voltage selection circuit, an input signal selection circuit and a working mode selection circuit;

the reference voltage selection circuit is used for controlling the negative end of the comparator to be connected with internal high-precision reference voltage or internal reference voltage;

the input signal selection circuit is used for controlling the positive end of the comparator to be connected with a battery voltage signal or a first external signal input end;

the working mode selection circuit is used for controlling a signal source connected with the positive end and the negative end of the comparator;

the comparison circuit is used for outputting a trigger signal according to an input signal;

the filter circuit is used for filtering the trigger signal output by the comparator to obtain a filtered metering signal;

and the counting circuit is used for triggering counting according to the metering signal.

2. The metering circuit of claim 1 wherein the reference voltage selection circuit comprises an internal high precision reference voltage input, an internal reference voltage input, a first controllable switch, and a first output;

the internal high-precision reference voltage input end and the internal reference voltage input end are respectively connected with the first output end through the first controllable switch;

the first controllable switch is used for selecting the internal high-precision reference voltage input end or the internal reference voltage input end to be communicated with the first output end according to a control signal.

3. The metering circuit of claim 2 wherein the input signal selection circuit comprises a first external signal input, a battery voltage signal input, a second controllable switch, and a second output;

the first external signal input end and the battery voltage signal input end are respectively connected with the second output end through the second controllable switch;

and the second controllable switch is used for selecting the first external signal input end or the battery voltage signal input end to be communicated with the second output end according to a control signal.

4. The metering circuit of claim 3 wherein the operating mode selection circuit comprises a third controllable switch, a fourth controllable switch, and a fifth controllable switch;

the third controllable switch is used for connecting the positive end of the comparator with the second output end of the input signal selection circuit and the negative end of the comparator with the first output end of the reference voltage selection circuit according to a control signal;

the fourth controllable switch is used for connecting the positive end and the second external signal input end of the comparator, the negative end of the comparator and the first output end of the reference voltage selection circuit according to a control signal;

the fifth controllable switch is configured to switch on the positive terminal of the comparator and the second output terminal of the input signal selection circuit and the negative terminal of the comparator and the second external signal input terminal according to a control signal.

5. The metering circuit of any one of claims 1 to 4, wherein the filter circuit is configured to determine whether the trigger signal output by the comparator is continuously unchanged within a preset first time period; if the trigger signal is not changed continuously in the first time period, the trigger signal is subjected to jitter elimination according to a preset jitter elimination period to obtain a jitter elimination signal; judging whether the jitter elimination signal is continuously unchanged in a preset second time period; and if the jitter elimination signal is 1 continuously in the second time period, outputting the jitter elimination signal as the metering signal.

6. The metering circuit of claim 5, wherein the counting circuit is specifically configured to count signal edges of the metering signal, and when the count value reaches a preset count threshold, trigger an interrupt signal to the MCU, so that the MCU updates a local count according to the count of the metering circuit and resets the count of the metering circuit.

7. The metering circuit of claim 6, further comprising: a battery alarm circuit;

and the battery alarm circuit is used for giving an alarm according to the trigger signal output by the comparator when the comparator works in the battery detection mode so as to prompt that the battery is low in electric quantity.

8. A water and gas meter, comprising: an impeller, a magnetic field inductor and a metering circuit as claimed in any one of claims 1 to 7;

the impeller is provided with a magnet, and the magnetic field inductor is connected with the metering circuit;

the magnetic field inductor is used for detecting a magnetic field signal sent by a magnet rotating on the impeller, sending a corresponding electric signal to the metering circuit, and recording the number of rotation turns of the impeller according to the electric signal to obtain the digital signal type water-gas meter counting.

9. The water-gas meter of claim 8, further comprising: the display module is connected with the metering circuit;

and the display module is used for displaying the water-gas meter counting.

Background

Along with the development of economic society, the living conditions of people also become more and more intelligent, intelligent home is gradually popularized, and various devices can be networked to realize automatic monitoring.

In the prior art, the traditional water-gas meter is still used, the state of the water-gas meter can be known only when workers arrive at the site in the using process of the traditional water-gas meter, so that the working state of the water-gas meter is mastered and updated with a hysteresis phenomenon, and the monitoring is difficult.

Therefore, a water-gas meter which can monitor more conveniently and has lower cost is needed.

Disclosure of Invention

In view of this, the present invention provides a metering circuit and a water/gas meter, which are more convenient to monitor and have lower power consumption and cost. The specific scheme is as follows:

a metering circuit, comprising: the comparison circuit, the filter circuit and the counting circuit are connected in sequence;

the comparison circuit comprises a comparison mode selection circuit and a comparator;

the comparison mode selection circuit comprises a reference voltage selection circuit, an input signal selection circuit and a working mode selection circuit;

the reference voltage selection circuit is used for controlling the negative end of the comparator to be connected with internal high-precision reference voltage or internal reference voltage;

the input signal selection circuit is used for controlling the positive end of the comparator to be connected with a battery voltage signal or a first external signal input end;

the working mode selection circuit is used for controlling a signal source connected with the positive end and the negative end of the comparator;

the comparison circuit is used for outputting a trigger signal according to an input signal;

the filter circuit is used for filtering the trigger signal output by the comparator to obtain a filtered metering signal;

and the counting circuit is used for triggering counting according to the metering signal.

Optionally, the reference voltage selection circuit includes an internal high-precision reference voltage input terminal, an internal reference voltage input terminal, a first controllable switch, and a first output terminal;

the internal high-precision reference voltage input end and the internal reference voltage input end are respectively connected with the first output end through the first controllable switch;

the first controllable switch is used for selecting the internal high-precision reference voltage input end or the internal reference voltage input end to be communicated with the first output end according to a control signal.

Optionally, the input signal selection circuit includes a first external signal input terminal, a battery voltage signal input terminal, a second controllable switch, and a second output terminal;

the first external signal input end and the battery voltage signal input end are respectively connected with the second output end through the second controllable switch;

and the second controllable switch is used for selecting the first external signal input end or the battery voltage signal input end to be communicated with the second output end according to a control signal.

Optionally, the operating mode selection circuit includes a third controllable switch, a fourth controllable switch and a fifth controllable switch;

the third controllable switch is used for connecting the positive end of the comparator with the second output end of the input signal selection circuit and the negative end of the comparator with the first output end of the reference voltage selection circuit according to a control signal;

the fourth controllable switch is used for connecting the positive end and the second external signal input end of the comparator, the negative end of the comparator and the first output end of the reference voltage selection circuit according to a control signal;

the fifth controllable switch is configured to switch on the positive terminal of the comparator and the second output terminal of the input signal selection circuit and the negative terminal of the comparator and the second external signal input terminal according to a control signal.

Optionally, the filter circuit is configured to determine whether the trigger signal output by the comparator is continuously unchanged within a preset first time period; if the trigger signal is not changed continuously in the first time period, the trigger signal is subjected to jitter elimination according to a preset jitter elimination period to obtain a jitter elimination signal; judging whether the jitter elimination signal is continuously unchanged in a preset second time period; and if the jitter elimination signal is 1 continuously in the second time period, outputting the jitter elimination signal as the metering signal.

Optionally, the counting circuit is specifically configured to count signal edges of the metering signal, and when the count value reaches a preset count threshold, trigger an interrupt signal to the MCU, so that the MCU updates local counting according to the count of the metering circuit, and resets the count of the metering circuit.

Optionally, the method further includes: a battery alarm circuit;

and the battery alarm circuit is used for giving an alarm according to the trigger signal output by the comparator when the comparator works in the battery detection mode so as to prompt that the battery is low in electric quantity.

The invention also discloses a water-gas meter, comprising: an impeller, a magnetic field inductor and a metering circuit as previously described;

the impeller is provided with a magnet, and the magnetic field inductor is connected with the metering circuit;

the magnetic field inductor is used for detecting a magnetic field signal sent by a magnet rotating on the impeller, sending a corresponding electric signal to the metering circuit, and recording the number of rotation turns of the impeller according to the electric signal to obtain the digital signal type water-gas meter counting.

Optionally, the method further includes: the display module is connected with the metering circuit;

and the display module is used for displaying the water-gas meter counting.

In the present invention, the metering circuit includes: the comparison circuit, the filter circuit and the counting circuit are connected in sequence; the comparison circuit comprises a comparison mode selection circuit and a comparator; the comparison mode selection circuit comprises a reference voltage selection circuit, an input signal selection circuit and a working mode selection circuit; the reference voltage selection circuit is used for controlling the negative end of the comparator to be connected with internal high-precision reference voltage or internal reference voltage; the input signal selection circuit is used for controlling the positive end of the comparator to be connected with a battery voltage signal or a first external signal input end; the working mode selection circuit is used for controlling a signal source connected with the positive end and the negative end of the comparator; the comparison circuit is used for outputting a trigger signal according to an input signal; the filter circuit is used for filtering the trigger signal output by the comparator to obtain a filtered metering signal; and the counting circuit is used for triggering counting according to the metering signal.

The invention utilizes one comparator to realize the switching of various working modes by matching with three selection circuits, namely the reference voltage selection circuit, the input signal selection circuit and the working mode selection circuit, does not need to design a corresponding independent comparison circuit for each working mode, saves the cost, and reduces the power consumption due to the reduction of large-scale components in the circuit.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of a measurement circuit according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a water-gas meter disclosed in the embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention discloses a metering circuit, which is shown in figure 1 and comprises the following components: the device comprises a comparison circuit 1, a filter circuit 2 and a counting circuit 3 which are connected in sequence;

the comparison circuit 1 includes a comparison mode selection circuit 11 and a comparator 12;

the comparison mode selection circuit 11 includes a reference voltage selection circuit 111, an input signal selection circuit 112, and an operation mode selection circuit 113;

a reference voltage selection circuit 111 for controlling the negative terminal of the comparator 12 to access the internal high-precision reference voltage BGPREF or the internal reference voltage VREF;

an input signal selection circuit 112, configured to control the positive terminal of the comparator 12 to access the battery voltage signal BAT or the first external signal input terminal CMP _ P;

a working mode selection circuit 113 for controlling the signal source connected to the positive terminal and the negative terminal of the comparator 12;

a comparison circuit 1 for outputting a trigger signal CMP _ OUT according to an input signal;

the filter circuit 2 is configured to filter the trigger signal CMP _ OUT output by the comparator 12 to obtain a filtered metering signal;

and the counting circuit 3 is used for triggering counting according to the metering signal.

Specifically, in order to save circuit cost, multiple working modes are integrated in one comparison circuit 1 through a comparison mode selection circuit 11, only one comparator 12 is needed, and multiple selection circuits are matched, so that multiple working modes can be matched, corresponding independent comparison circuits 1 do not need to be designed for each working mode, and cost is saved.

Specifically, the negative terminal of the comparator 12 can be selected to access the internal high-precision reference voltage BGPREF or the internal reference voltage VREF through the reference voltage selection circuit 111, the internal reference voltage VREF of the common precision can be selected when the precision requirement is low, so that the power is saved, the energy is saved, the internal high-precision reference voltage BGPREF can be selected when the precision requirement is high, the higher-precision reference voltage is provided, the precision of the comparison result of the comparator 12 is ensured, and the precision is improved.

Specifically, the input signal selection circuit 112 may select to access the battery voltage signal BAT to provide a basic design for subsequent determination of the battery state, and the first external signal input terminal CMP _ P may allow the metering circuit to meter different inputs, for example, the first external signal input terminal CMP _ P may be externally connected to a magnetic field sensor to meter according to an electrical signal output by the magnetic field sensor.

Specifically, the second external input signal source may be added through the operation mode selection circuit 113, and the connection combination of the positive terminal and the negative terminal of the comparator 12 may be selected, for example, the positive terminal of the comparator 12 may be connected to the input signal selection circuit 112, the negative terminal of the comparator 12 may be connected to the reference voltage selection circuit 111, or the positive terminal of the comparator 12 may be connected to the second external input signal source, the negative terminal of the comparator 12 may be connected to the reference voltage selection circuit 111, or the positive terminal of the comparator 12 may be connected to the reference voltage selection circuit 111, or the negative terminal of the comparator 12 may be connected to the second external input signal source, so as to provide a plurality of operation modes.

In addition, the output of the comparator 12 is filtered by the filter circuit 2, so that the accuracy of the measurement of the subsequent counting circuit 3 is ensured.

It can be understood that the mode switching of the reference voltage selection circuit 111, the input signal selection circuit 112 and the operation mode selection circuit 113 can utilize one or more simple multi-path controllable switches to implement the input change, so as to ensure low cost, and meanwhile, the input signal of the controllable switch can be implemented by an external corresponding control circuit, which is not described herein.

It can be seen that in the embodiment of the present invention, one comparator 12 is used, and the reference voltage selection circuit 111, the input signal selection circuit 112, and the working mode selection circuit 113 are used in cooperation to implement switching of multiple working modes, so that it is no longer necessary to design a corresponding independent comparison circuit 1 for each working mode, thereby saving cost, and reducing power consumption due to the reduction of large components in the circuit.

The embodiment of the invention discloses a specific metering circuit, and compared with the previous embodiment, the technical scheme is further explained and optimized in the embodiment. Referring to fig. 1, specifically:

specifically, the reference voltage selection circuit 111 includes an internal high-precision reference voltage BGPREF input terminal, an internal reference voltage VREF input terminal, a first controllable switch 1111, and a first output terminal REF;

the input end of the internal high-precision reference voltage BGPREF and the input end of the internal reference voltage VREF are respectively connected with a first output end REF through a first controllable switch 1111;

a first controllable switch 1111 for selecting the input terminal of the internal high precision reference voltage BGPREF or the input terminal of the internal reference voltage VREF to communicate with the first output terminal REF according to the control signal.

Specifically, the input signal selection circuit 112 includes a first external signal input terminal CMP _ P, a battery voltage signal BAT input terminal, a second controllable switch 1121, and a second output terminal CMP1_ P;

the first external signal input terminal CMP _ P and the battery voltage signal BAT input terminal are respectively connected with the second output terminal CMP1_ P through the second controllable switch 1121;

the second controllable switch 1121 is configured to select the first external signal input terminal CMP _ P or the battery voltage signal BAT input terminal to be communicated with the second output terminal CMP1_ P according to the control signal.

Specifically, the operation mode selection circuit 113 includes a third controllable switch 1131, a fourth controllable switch 1132 and a fifth controllable switch 1133;

a third controllable switch 1131, for switching on the positive terminal of the comparator 12 and the second output terminal CMP1_ P of the input signal selection circuit 112 and the negative terminal of the comparator 12 and the first output terminal REF of the reference voltage selection circuit 111 according to the control signal;

a fourth controllable switch 1132 for switching on the positive terminal and the second external signal input terminal of the comparator 12 and the negative terminal of the comparator 12 and the first output terminal REF of the reference voltage selection circuit 111 according to the control signal;

a fifth controllable switch 1133 for switching on the positive terminal of the comparator 12 and the second output terminal CMP1_ P of the input signal selection circuit 112 and the negative terminal of the comparator 12 and the second external signal input terminal according to the control signal.

Specifically, referring to fig. 1, the various comparison modes of the comparator 12 are specifically: 1. the positive terminal of the comparator 12 is connected to the pin CMP _ P, i.e. the first external signal input terminal CMP _ P, and the negative terminal is connected to the pin CMP _ N, i.e. the second external signal input terminal; 2. the positive end of the comparator 12 is connected with a pin CMP _ P, and the negative end is connected with an internal high-precision reference voltage BGPREF or an internal reference voltage VREF through a signal; 3. the positive end of the comparator 12 is connected with a pin CMP _ N, and the negative end is connected with an internal high-precision reference voltage BGPREF or an internal reference voltage VREF through a signal; 4. the positive terminal of the comparator 12 is connected to the pin battery voltage BAT, and the negative terminal is connected to the internal high-precision reference voltage BGPREF or the internal reference voltage VREF by a signal.

The first controllable switch 1111 controls to select the source of the REF signal: VREF or BGPREF; the second controllable switch 1121 controls the selection of the source of the CMP1_ P signal: CMP _ P or BAT; the operation mode selection circuit 113 can control the operation mode according to three codes, for example, 00: CMP1_ P and REF, 01: CMP _ N and REF, 10: CMP1_ P and CMP _ N.

Wherein, the CMPPDN end controls the enabling of the comparator 12.

Specifically, the filter circuit 2 is configured to determine whether the trigger signal CMP _ OUT output by the comparator 12 is continuously unchanged within a preset first time period; if the trigger signal is not changed continuously in the first time period, the trigger signal is subjected to jitter elimination according to a preset jitter elimination period to obtain a jitter elimination signal; judging whether the jitter elimination signal is continuously unchanged in a preset second time period; and if the jitter elimination signal is 1 continuously in the second time period, outputting the jitter elimination signal as the metering signal.

The filter circuit 2 eliminates jitter of the trigger signal CMP _ OUT to obtain a smooth and flat waveform. The filter circuit 2 comprises 2 stages of control logic, the first stage is jitter cancellation control, and at most 4 clock cycles can be selected for jitter cancellation, i.e. a jitter cancellation period can comprise 1 to 4 cycles. When the first stage debounce is enabled, the input signal is only valid if the trigger signal CMP _ OUT has not changed within a number of cycles of the RTCCLK clock, i.e., within a first time period, at which point the debounced input signal is taken as the debounce signal. The second stage is output result determination control, and outputs the jitter elimination signal as the metering signal if the output signal of the trigger signal CMP _ OUT subjected to jitter elimination of the first stage is still continuously preset for a second time period CMP1_ CHK _ NUM of 1, for example, if the output signal of the trigger signal CMP _ OUT subjected to jitter elimination of the first stage is all 1 signals in the continuous second time period, it is determined that the output result is 1, and the jitter elimination signal is output as the metering signal. The specific value of the second time period CMP1_ CHK _ NUM can be set to any value from 0 to 15.

Specifically, the counting circuit 3 may be specifically configured to count a signal edge of the metering signal, and when the count value reaches a preset count threshold, trigger an interrupt signal to an MCU (micro controller Unit) so that the MCU updates a local count according to the count of the metering circuit and resets the count of the metering circuit.

Specifically, the signal edge may include a rising edge, a falling edge, or a double edge of the signal, and the count value of the counting circuit 3 is increased by one after the corresponding signal edge is detected until the count value reaches a preset count threshold, for example, the count threshold may be 100, and when the count in the counting circuit 3 reaches 100, an interrupt signal is triggered, the interrupt signal is transmitted to the MCU, so that the MCU increments by one according to the interrupt signal of the metering circuit, for example, the number of times that the counting circuit 3 has previously triggered the interrupt is recorded in the MCU as 30 times, after receiving the interrupt signal of the counting circuit 3 again, the MCU counts up by one to 31 times, meanwhile, in order to save the device cost, the counting circuit 3 with lower upper limit of counting can be selected, therefore, the MCU clears the counting of the counting circuit 3 every time the counting threshold is reached, so that the counting circuit 3 can continue counting, the specific clearing method may be to make the counting circuit 3 count and subtract the counting threshold.

Wherein, before the counter exports interrupt signal to MCU, MCU can be in the dormant state, only after the counter exports interrupt signal to MCU, MCU just is awaken by interrupt signal, lets MCU enter operating condition and counts according to interrupt signal, can reduce MCU's power consumptive like this, extension battery life.

Specifically, the method may further include: a battery alarm circuit; wherein the content of the first and second substances,

and the battery alarm circuit is used for giving an alarm according to the trigger signal CMP _ OUT output by the comparator 12 when working in the battery detection mode so as to prompt that the battery is low in power.

Specifically, a battery is needed in the circuit to provide power for each device, for example, a battery is needed in a water-gas meter, each power utilization circuit and device such as a magnetic field sensor and a metering circuit need to be driven, in order to avoid the situation that equipment cannot normally work due to the fact that the battery is not replaced in time and the power is low, a battery alarm circuit is arranged, a battery voltage signal BAT is accessed to the positive end of a circuit of the comparator 12, a reference signal is accessed to the negative end of the circuit, the comparator 12 can work in a battery detection mode, the trigger signal CMP _ OUT output by the comparator 12 in the mode corresponds to the low power of the battery, and after the battery alarm circuit receives the trigger signal CMP _ OUT, the alarm can give an alarm to prompt that the power of the battery is low.

Further, an embodiment of the present invention further discloses a water-gas meter, as shown in fig. 2, including: an impeller 4, a magnetic field inductor 5 and a metering circuit 6 as previously described;

the impeller 4 is provided with a magnet 41, and the magnetic field inductor 5 is connected with the metering circuit 6;

the magnetic field inductor 5 is used for detecting a magnetic field signal sent by the magnet 41 rotating on the impeller 4 and sending a corresponding electric signal to the metering circuit 6;

and the metering circuit 6 is used for recording the rotation turns of the impeller 4 according to the electric signal to obtain the water-gas meter counting in the form of digital signals.

Specifically, the magnet 41 is mounted on the impeller 4 by utilizing the principle of electromagnetic induction, so that the impeller 4 generates a corresponding magnetic field during one rotation, and the magnetic field sensor 5 detects a magnetic field signal generated by the magnet 41 rotating on the impeller 4, thereby indirectly obtaining the number of cycles of the rotation of the impeller 4.

Specifically, the metering circuit 6 can obtain the water-gas meter count stored in a digital signal form after counting, at the moment, the water-gas meter count can be transmitted to corresponding display equipment or statistical equipment through any communication means, remote meter reading and remote monitoring are realized, and in order to realize remote control, a corresponding remote control circuit can be arranged in the water-gas meter, a control instruction of the MCU is received, and the opening and closing of a valve in the water-gas meter is controlled.

Therefore, in the embodiment of the invention, the magnet 41 is arranged on the impeller 4, the magnetic field inductor 5 is matched, the rotation angle of the impeller 4 is converted into an electric signal, and the electric signal is measured by the metering circuit 6, so that the water-gas meter counting in a digital signal form is obtained, the digital metering is realized, the basis is provided for the subsequent remote monitoring, and meanwhile, the metering circuit with low power consumption and low cost is used, so that the overall power consumption and cost of the water-gas meter are also reduced.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The technical content provided by the present invention is described in detail above, and the principle and the implementation of the present invention are explained in this document by applying specific examples, and the above description of the examples is only used to help understanding the method of the present invention and the core idea thereof; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.