Current-frequency conversion circuit, conversion method and system thereof

Abstract

The present invention provides a current-frequency conversion circuit, conversion method, and system thereof, comprising: an integration circuit, a microprocessor, a control circuit, an analog switch, and a constant current source; wherein the microprocessor obtains a first integrated voltage output by the integration circuit, determines the voltage interval in which the first integrated voltage is located, and then outputs the judgment result to the control circuit; the voltage interval represents the interval division of the input voltage of the microprocessor; the control circuit outputs a corresponding number of pulse signals based on the judgment result; when the number of the output pulse signals reaches a preset value, the control circuit controls the analog switch to conduct so that the feedback current output by the constant current source is output to the input end of the integration circuit through the analog switch. According to the current-frequency conversion circuit of the present invention, multiple voltage intervals are set and the corresponding number of pulse signals are output in sequence to achieve the sensitivity and resolution of the current-frequency conversion circuit.

Description

Technical Field

[0001] The present invention relates to the field of inertial navigation, and in particular to a current-frequency conversion circuit, a conversion method and a system thereof. Background Art

[0002] The current-to-frequency (I / F) conversion circuit is a high-precision conversion circuit based on the principle of charge balance. It converts analog current into frequency pulses and is widely used in the field of inertial navigation. Its main process is as follows: the I / F conversion circuit acquires the current signal output by the accelerometer and converts it into a frequency signal. When the accelerometer outputs positive current, the positive channel of the I / F conversion circuit outputs a frequency; when the accelerometer outputs negative current, the negative channel of the I / F conversion circuit outputs a frequency. The I / F conversion circuit responds highly sensitively to the accelerometer output. The faster the response, the higher the sensitivity and resolution of the I / F conversion circuit, which is crucial for the real-time performance of inertial navigation.

[0003] Traditional current-to-frequency conversion circuits have two thresholds: a high threshold and a low threshold. During the conversion process, the charge is integrated, causing the output voltage to rise from zero or fall. When the high or low threshold is reached, a pulse is output as feedback.

[0004] However, in the process of implementing the technical solutions of the present invention in the embodiments of the present invention, the inventors of the present application found that the above technology has at least the following technical problems: the design solutions in the existing technology have low resolution, and there will be a long resolution delay when the current is commutated. Summary of the Invention

[0005] In view of the problem of low resolution of the design scheme of the current-frequency conversion circuit in the above-mentioned prior art, the present invention is proposed to provide a current-frequency conversion circuit, conversion method and system thereof that overcome the above-mentioned problem or at least partially solve the above-mentioned problem.

[0006] According to one aspect of the present invention, a current-frequency conversion circuit is provided, comprising: an integration circuit, a microprocessor, a control circuit, an analog switch, and a constant current source; wherein,

[0007] The microprocessor obtains a first integrated voltage output by the integration circuit, determines a voltage interval in which the first integrated voltage is located, and outputs a determination result to the control circuit; the voltage interval represents an interval division of the input voltage of the microprocessor;

[0008] The control circuit outputs a corresponding number of pulse signals according to the judgment result and the number of pulse signals output;

[0009] When the number of the output pulse signals reaches a preset value, the control circuit controls the analog switch to be turned on so that the feedback current output by the constant current source is output to the input end of the integration circuit through the analog switch.

[0010] Preferably, the current-frequency conversion circuit further includes: a clamping diode connected to the microprocessor for clamping protection of an input port of the microprocessor.

[0011] Preferably, the current-frequency conversion circuit further includes: a feedback circuit connected to the output end of the integration circuit, and configured to add a bias voltage to the first integration voltage output by the integration circuit to obtain a second integration voltage.

[0012] Preferably, the voltage range includes: an upper threshold range and a lower threshold range; wherein,

[0013] A voltage interval higher than the bias voltage is an upper threshold interval, and a voltage interval lower than the bias voltage is a lower threshold interval. Both the upper threshold interval and the lower threshold interval are located in a positive voltage interval.

[0014] According to another aspect of the present invention, there is provided a current-frequency conversion method, comprising:

[0015] The microprocessor obtains a first integrated voltage output by the integration circuit and determines a voltage interval in which the first integrated voltage is located; the voltage interval represents the interval division of the input voltage of the microprocessor;

[0016] outputting a judgment result to a control circuit according to the voltage interval in which the first integrated voltage is located;

[0017] The control circuit outputs a corresponding number of pulse signals according to the judgment result and the number of pulse signals that have been output;

[0018] When the number of the output pulse signals reaches a preset value, the control circuit controls the analog switch to be turned on so that the constant current source outputs a feedback current to the integration circuit.

[0019] Preferably, before the microprocessor obtains the first integrated voltage output by the integration circuit, the method further includes:

[0020] A feedback signal is output to the output terminal of the integration circuit to add a bias voltage to the first integration voltage to obtain a second integration voltage.

[0021] Preferably, the voltage range includes: an upper threshold range and a lower threshold range, wherein the voltage range higher than the bias voltage is the upper threshold range, and the voltage range lower than the bias voltage is the lower threshold range, and the upper threshold range and the lower threshold range are both in the positive voltage range;

[0022] When a negative input current is input to the integration circuit, the second integration voltage is located in the upper threshold range;

[0023] When the integration circuit inputs a forward input current, the second integration voltage is located in the lower threshold range.

[0024] Preferably, after the constant current source outputs the feedback current to the integration circuit, the method further comprises: when the second integration voltage is lower than a lower threshold interval or higher than an upper threshold interval, clearing the number of the pulse signals.

[0025] Preferably, the method specifically includes:

[0026] When the number of the pulse signals does not reach the preset value and the input current obtained by the integration circuit changes linearly, the number of the pulse signals is the difference between the number of pulse signals corresponding to the voltage interval in which the second integrated voltage obtained this time is located and the number of pulse signals corresponding to the voltage interval in which the second integrated voltage obtained last time is located;

[0027] When the number of the pulse signals does not reach the preset value and the input current is commutated, the number of the pulse signals is the difference between the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained last time and the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained this time.

[0028] According to another aspect of the present invention, a current-frequency conversion system is also provided, comprising: a clock circuit, a temperature compensation circuit, an output circuit, and the current-frequency conversion circuit as described above, wherein the current-frequency conversion circuit receives a current signal output by an accelerometer and converts it into a pulse signal, the temperature compensation circuit performs temperature compensation on the current-frequency conversion circuit, the clock circuit provides a clock signal for the current-frequency conversion circuit, and the output circuit increases a driving current for the current-frequency conversion circuit.

[0029] According to the present invention, the current-frequency conversion circuit is provided with multiple voltage intervals and sequentially outputs a corresponding number of pulse signals to achieve the conversion sensitivity and resolution of the current-frequency conversion circuit.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 is a circuit diagram of a current-frequency conversion circuit in an embodiment of the present invention;

[0033] Figure 2 This is a flow chart of a current-frequency conversion method according to an embodiment of the present invention;

[0034] Figure 3 Schematic diagram of the relationship between the voltage interval and the pulse signal in an embodiment of the present invention;

[0035] Figure 4 4 is a circuit diagram of a current-to-frequency conversion system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] An embodiment of the present invention provides a current-frequency conversion circuit, including: an integration circuit 101 , a microprocessor 102 , a control circuit 103 , an analog switch 104 , and a constant current source 105 .

[0038] The microprocessor 102 obtains the first integrated voltage output by the integration circuit 101, determines the voltage range within which the first integrated voltage falls, and then outputs the determination result to the control circuit 103. The voltage range represents the division of the input voltage of the microprocessor. Specifically, the output voltage of the integration circuit is obtained according to the sampling frequency of the microprocessor to obtain the first integrated voltage. This first integrated voltage is the voltage output by the integration circuit during sampling by the microprocessor. Thus, the microprocessor obtains a first integrated voltage each time it samples.

[0039] After obtaining the first integrated voltage, the microprocessor 102 needs to determine the voltage range within which the first integrated voltage falls to obtain a determination result. In other words, the microprocessor 102 is pre-set with multiple voltage ranges, which divide the input voltage range of the microprocessor 102. In a specific embodiment of the present invention, assuming that there are M voltage ranges, when the input current is negative, the output voltage of the integration circuit exhibits a gradually increasing linear trend and falls into the first voltage range, the second voltage range, and so on to the Nth voltage range.

[0040] When the microprocessor 102 obtains the output voltage of the integration circuit 101 at the first sampling moment, that is, the first first integrated voltage, it determines the voltage range in which the first integrated voltage is located and outputs the obtained determination result to the control circuit 103 .

[0041] The control circuit 103 outputs a corresponding number of pulse signals based on the above-mentioned determination result and the number of pulse signals output. The number of pulse signals output can be adjusted according to actual conditions. The voltage range of the first integrated voltage corresponds to the number of pulse signals output.

[0042] In a specific embodiment, for example, before the first integral voltage is obtained, no pulse signal is output, that is, the number of pulse signals that have been output is zero; after the first integral voltage is obtained, the judgment result is that the first integral voltage is located in the first voltage interval, then the control circuit determines that 1 pulse signal should be output based on the judgment result and the number of pulse signals that have been output; the judgment result is that the first integral voltage is located in the second voltage interval, then according to the judgment result and the number of pulse signals that have been output, it is determined that 2 pulse signals should be output, and so on.

[0043] In another specific embodiment, when the first first integrated voltage obtained by the microprocessor during the first sampling is located in the first voltage interval, the control circuit should output 1 pulse signal; during the second sampling, after obtaining the second first integrated voltage output by the integration circuit, the judgment result is that the second first integrated voltage is located in the M-1 voltage interval, then combined with the judgment result, M-1 pulse signals should be output in the M-1 voltage interval. Since 1 pulse signal has been output when the first first integrated voltage was located in the first voltage interval, M-2 pulse signals should be output at this moment, that is, when the first integrated voltage is in the M-1 voltage interval, a total of M-1 pulse signals should be output.

[0044] When the number of pulse signals output reaches a preset value, the control circuit 103 controls the analog switch 104 to conduct, so that the feedback current output by the constant current source passes through the analog switch and outputs the feedback signal to the input terminal of the integration circuit. Taking the above specific embodiment as an example, when there are M voltage intervals, then when the Mth voltage interval is reached, M pulse signals are output. At this time, the number of pulse signals output reaches the preset value, and the control circuit controls the analog switch to conduct for one clock cycle, causing the constant current source to perform a feedback to output the feedback current to the input terminal of the integration circuit.

[0045] In a preferred embodiment, after outputting the feedback current, negative feedback raises or lowers the first integrated voltage. If the first integrated voltage after feedback is lower than or higher than the voltage interval, the above scheme is restarted. If the first integrated voltage is still within a certain voltage interval, a corresponding pulse signal is output, and the above scheme is continued in the same manner until the number of pulse signals corresponding to the first integrated voltage reaches the preset value again, at which time the feedback signal is output again.

[0046] Through the current-frequency conversion circuit described in the above embodiment of the present invention, the integrated first integrated voltage is compared with multiple voltage intervals, and a corresponding pulse signal is output based on the comparison result and the number of pulse signals that have been output. When the number of pulse signals reaches a certain number, feedback is provided, thereby improving the resolution of the circuit and having important significance for the real-time performance of inertial navigation.

[0047] The current-to-frequency conversion circuit according to an embodiment of the present invention preferably further includes a clamping diode connected to the microprocessor for clamping protection of the microprocessor's input port. Specifically, since the voltage of the microprocessor's input port has a certain range, to provide clamping protection for the input port, clamping diodes in positive and negative directions are designed at the microprocessor's input port to protect the microprocessor from damage caused by excessive voltage.

[0048] In a current-frequency conversion circuit according to an embodiment of the present invention, preferably, the current-frequency conversion circuit further includes: a feedback circuit connected to the output terminal of the integration circuit, configured to add a bias voltage to the first integrated voltage output by the integration circuit to obtain a second integrated voltage. Specifically, in existing current-frequency conversion circuits, the input current and the first integrated voltage are in opposite directions, i.e., when the current is 0 mA, the first integrated voltage is 0 V. When the integration circuit receives a positive input current, the output first integrated voltage is negative; when the integration circuit receives a negative input current, the output first integrated voltage is positive. Therefore, different comparators are required to achieve pulse signal output according to the direction of the input current. In the current-frequency conversion circuit according to an embodiment of the present invention, a bias voltage is output to the output terminal of the integration circuit via the feedback circuit, so that the second integrated voltage output at the output terminal of the integration circuit is the sum of the original output voltage and the bias voltage. For example, when the input current of the integration circuit is 0 mA, the first integrated voltage is stabilized at the bias voltage, thereby adjusting the output of the second integrated voltage to always be in the positive voltage range, thus solving the voltage direction problem.

[0049] In a preferred embodiment, when the microprocessor voltage range is 0 to U, the intermediate value U / 2 can be selected as the bias voltage applied to the output of the integrator circuit. Thus, when the input current of the integrator circuit is 0 mA, the second integrated voltage is U / 2 V. When a positive input current is applied, the second integrated voltage decreases toward a value below U / 2 V, and when a negative input current is applied, the second integrated voltage increases toward a value above U / 2 V.

[0050] In the current-frequency conversion circuit described in an embodiment of the present invention, preferably, the voltage range includes: an upper threshold range and a lower threshold range; wherein the voltage range above the bias voltage is the upper threshold range, and the voltage range below the bias voltage is the lower threshold range, and both the upper threshold range and the lower threshold range are located in the positive voltage range. Taking the above embodiment as an example, the voltage range below U / 2V is the lower threshold range, and the voltage range above U / 2V is the upper threshold range, and both the upper threshold range and the lower threshold range are within the voltage U, and therefore are both positive voltage ranges. That is, when a positive input current is received, the second integrated voltage varies within the lower threshold range; when a negative input current is received, the second integrated voltage varies within the upper threshold range.

[0051] The embodiment of the present invention also provides a current frequency conversion method, such as Figure 2 Shown, including:

[0052] Step 201: The microprocessor obtains a first integrated voltage output by an integration circuit and determines a voltage interval in which the first integrated voltage is located; the voltage interval represents the interval division of the input voltage of the microprocessor;

[0053] Step 202: outputting a determination result to a control circuit according to the voltage interval in which the first integrated voltage is located;

[0054] Step 203: the control circuit outputs a corresponding number of pulse signals according to the judgment result and the number of pulse signals that have been output;

[0055] Step 204 : When the number of the output pulse signals reaches a preset value, the control circuit controls the analog switch to be turned on so that the constant current source outputs a feedback current to the integration circuit.

[0056] In the current-frequency conversion method according to an embodiment of the present invention, preferably, before the microprocessor obtains the first integrated voltage output by the integration circuit, the method further includes:

[0057] A feedback signal is output to the output terminal of the integration circuit to add a bias voltage to the first integration voltage.

[0058] In the current-frequency conversion method according to an embodiment of the present invention, preferably, the voltage interval includes: an upper threshold interval and a lower threshold interval, wherein a voltage interval higher than the bias voltage is the upper threshold interval, and a voltage interval lower than the bias voltage is the lower threshold interval, and both the upper threshold interval and the lower threshold interval are located in a positive voltage interval;

[0059] When a negative input current is input to the integration circuit, the second integration voltage is located in the upper threshold range;

[0060] When the integration circuit inputs a forward input current, the second integration voltage is located in the lower threshold range.

[0061] In a current-frequency conversion method according to an embodiment of the present invention, preferably, after the constant current source outputs the feedback current to the integration circuit, the method further comprises: clearing the number of previously calculated pulse signals. Specifically, after the feedback signal is output, if the number of pulse signals is cleared to facilitate recounting, and if the second integrated voltage is still within a voltage range of the upper threshold range or the lower threshold range, then the corresponding number of pulse signals is still output.

[0062] The current-frequency conversion method described in an embodiment of the present invention preferably includes:

[0063] When the number of pulse signals is lower than the preset value and the input current obtained by the integration circuit changes linearly, the number of pulse signals is the difference between the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained this time and the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained last time. It can also be understood as the difference between the number of pulse signals corresponding to the voltage interval of the first integral voltage obtained this time and the number of pulse signals that have been output. Specifically, in this embodiment, the linear change of the input current obtained by the integration circuit means that the input current either rises linearly or falls linearly. In this case, there is no current turning point, that is, there is no current commutation. The number N of pulse signals can be obtained by the following formula:

[0064] N=F*A+AD(n)-AD(n-1)

[0065] When the second integrated voltage is still within a certain threshold range, F=0 and AD(n)>=AD(n-1)

[0066] When the second integrated voltage exceeds the threshold range, F = 1 and AD(n) = 0. At this time, the number of pulse signals reaches the preset value A.

[0067] When the input current is commutating, the number of pulse signals is the difference between the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained last time and the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained this time. That is, the formula can be used:

[0068] N=AD(n-1)-AD(n) AD(n)<AD(n-1)

[0069] Get the number N of pulse signals.

[0070] Among them, F is the adjustment coefficient, AD(n) represents the number n of pulse signals that should be output corresponding to the voltage interval reached by the second integrated voltage obtained for the nth time, AD(n-1) represents the number n-1 of pulse signals that should be output corresponding to the voltage interval reached by the second integrated voltage obtained for the n-1th time, and A is the preset value of the number of pulse signals.

[0071] The solution of the present invention is fully described below with a specific embodiment.

[0072] In one embodiment, the sampling range of the analog-to-digital converter on a microprocessor, i.e., the output voltage range of the microprocessor, is 0-3.3V. To match this sampling range, the voltage input range of 0-3.3V needs to be quantized into intervals. Specifically, after the current-to-frequency conversion circuit is powered on, a feedback pulse output by the feedback circuit pre-increases a 1.6V offset voltage to the first integrated voltage to generate a second integrated voltage. This ensures that when the input current of the integrating circuit is 0 mA, the second integrated voltage stabilizes at 1.6V. When a positive input current is applied, the second integrated voltage decreases toward below 1.6V, and when a negative input current is applied, the second integrated voltage increases toward above 1.6V. Therefore, the voltage range above the offset voltage is the upper threshold range, i.e., the voltage range between 1.6V and 3.3V, and the voltage range below the offset voltage is the lower threshold range, i.e., the voltage range between 0V and 1.6V.

[0073] Specifically, to prevent the conversion result from being severely affected by microprocessor noise due to a small voltage difference between the thresholds, this embodiment uses the aforementioned eight upper threshold intervals and eight lower threshold intervals as examples to illustrate the current-to-frequency conversion steps. 1.8V, 1.9V, 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, and 2.5V are selected as the upper threshold margins, and 0.7V, 0.8V, 0.9V, 1.0V, 1.1V, 1.2V, 1.3V, and 1.4V are selected as the lower threshold margins. The interval between any two adjacent margins, as well as any interval exceeding the upper or lower threshold margins, is defined as a voltage interval. In other words, the eight upper thresholds are 1.8V to 1.9V, 1.9V to 2.0V, 2.0V to 2.1V, 2.1V to 2.2V, 2.2V to 2.3V, 2.3V to 2.4V, 2.4V to 2.5V, and above 2.5V. The eight lower thresholds are below 0.7V, 0.7V to 0.8V, 0.8V to 0.9V, 0.9V to 1.0V, 1.0V to 1.1V, 1.1V to 1.2V, 1.2V to 1.3V, and 1.3V to 1.4V. The margin of each upper threshold, or the interval between the upper threshold margins, is typically 100mV to prevent ripple interference. At the same time, there is still margin between the minimum upper threshold margin value of 1.8V and the bias voltage of 1.6V or the maximum lower threshold margin value of 1.4V and the bias voltage of 1.6V to prevent the input current from being too large and the integration from being too fast. When the feedback has not arrived, the second integration voltage will exceed the input range of the analog-to-digital converter and cause errors.

[0074] like Figure 3As shown, eight lower thresholds of 0.7V or less, 0.7V to 0.8V, 0.8V to 0.9V, 0.9V to 1.0V, 1.0V to 1.1V, 1.1V to 1.2V, 1.2V to 1.3V, and 1.3V to 1.4V are taken as examples to specifically illustrate the embodiment of the present invention.

[0075] In this embodiment, the integration circuit receives a positive input current, causing the integrated voltage output by the integration circuit to decrease. During the first sampling operation of the microprocessor, the second integrated voltage obtained by the microprocessor is between 1.4V and 1.6V, having not yet passed through any voltage intervals. Therefore, the number of positive pulses outputted is zero. During the second sampling operation, the second integrated voltage obtained by the microprocessor is between 1.2V and 1.3V, having passed through two voltage intervals. The corresponding positive pulse output now has two pulses. Since the number of positive pulses outputted during the previous sampling operation was zero, two positive pulses should be outputted at this time. Similarly, when the second integrated voltage is less than 0.7V, that is, within the eighth lower threshold interval, a total of eight pulses have been output. At this point, the control circuit controls the analog switch to conduct for one clock cycle, providing negative feedback to the integration circuit to increase the second integrated voltage. If the second integrated voltage after feedback rises above 1.4V, meaning it is no longer within any voltage interval, counting restarts. During the second round of counting, when the integrated voltage drops to between 0.9V and 1.0V, the input current reverses, causing the integrated voltage to rise. Therefore, a negative pulse signal should be output during the next integrated voltage acquisition. Since the integrated voltage is between 1.1V and 1.2V, the calculation formula for input current reversal indicates that two negative pulse signals should be output at this time.

[0076] In another preferred embodiment of the present invention, since the analog-to-digital converter in the microprocessor has a sampling frequency and data processing cycles, each sampling requires a certain time interval. Therefore, it is possible that within a single time interval, the second integrated voltage may drop directly from 1.6V to a value within the lower threshold range of 0.8V-0.9V, i.e., to the sixth voltage range. Since no pulse signal was output previously, the current positive pulse output will contain six pulses. Therefore, according to the above formula N = F*++AD(n)-AD(n-1), N = 0*8+6-0 = 6.

[0077] The embodiment of the present invention also provides a current-frequency conversion system, such as Figure 4As shown, it includes: a clock circuit 401, a temperature compensation circuit 402, an output circuit 403, and a current-frequency conversion circuit 404 as described in any of the above specific embodiments, wherein the current-frequency conversion circuit 404 receives the current signal output by the accelerometer and converts it into a pulse signal, the temperature compensation circuit 402 performs temperature compensation on the current-frequency conversion circuit 404, the clock circuit 401 provides a clock signal for the current-frequency conversion circuit, and the output circuit increases the driving current for the current-frequency conversion circuit.

[0078] In a preferred embodiment, the microprocessor in the current-to-frequency conversion circuit uses an STM32F429 single-chip microcomputer, and the control circuit uses an EPM570T100I4. The STM32F429 chip has a 3.3V supply voltage and is equipped with an LT3083EFE chip. C34, C35, and C36 are filter capacitors, with C34 and C35 being 10uF and C36 having a capacitance of 104. Resistor R137 is connected to pin 7 of the chip. Pin 7, SET, is the set pin used to set the output voltage. R137 has a resistance of 66.5kΩ, corresponding to an output voltage of 3.3V.

[0079] The STM32F429 software is designed using C and Verilog languages. The STM32F429 first initializes after power-on and controls three 12-bit analog-to-electrical converters to sample the second integral voltage. After filtering, the voltage signal undergoes voltage interval comparison and the comparison result is sent to the control circuit. The control circuit obtains the judgment result sent by the analog-to-digital converter in the microprocessor and controls the interface circuit to output pulses based on the judgment result. At the same time, the control circuit controls the analog switch based on the comparison result to implement feedback control of the constant current source.

[0080] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0081] It should also be understood that in the embodiments of the present invention, the term "and / or" merely describes an association between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three possible situations: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0082] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0083] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0084] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0085] The units described as separate components may or may not be physically separate, and 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 these units may be selected according to actual needs to achieve the objectives of the embodiments of the present invention.

[0086] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0087] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0088] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A current-frequency conversion circuit, characterized in that: include: Integrator circuit, microprocessor, control circuit, analog switch and constant current source; wherein, The microprocessor obtains a first integrated voltage output by the integration circuit, determines a voltage interval in which the first integrated voltage is located, and outputs a determination result to the control circuit; the voltage interval represents an interval division of the input voltage of the microprocessor; The control circuit outputs a corresponding number of pulse signals according to the judgment result and the number of pulse signals that have been output; When the number of the output pulse signals reaches a preset value, the control circuit controls the analog switch to be turned on so that the feedback current output by the constant current source is output to the input end of the integration circuit through the analog switch; The current-frequency conversion circuit further includes: a feedback circuit connected to the output end of the integration circuit, configured to add a bias voltage to the first integration voltage output by the integration circuit to obtain a second integration voltage; The voltage range includes: an upper threshold range and a lower threshold range; wherein, A voltage interval higher than the bias voltage is an upper threshold interval, and a voltage interval lower than the bias voltage is a lower threshold interval. Both the upper threshold interval and the lower threshold interval are located in a positive voltage interval.

2. The current-frequency conversion circuit according to claim 1, characterized in that: The current-frequency conversion circuit further includes: a clamping diode connected to the microprocessor and used for clamping protection of the input port of the microprocessor.

3. A current frequency conversion method, characterized in that: include: The microprocessor obtains a first integrated voltage output by the integration circuit, and determines a voltage interval in which the first integrated voltage is located; The voltage interval represents the interval division of the input voltage of the microprocessor; outputting a judgment result to a control circuit according to the voltage interval in which the first integrated voltage is located; The control circuit outputs a corresponding number of pulse signals according to the judgment result and the number of pulse signals that have been output; When the number of the output pulse signals reaches a preset value, the control circuit controls the analog switch to be turned on so that the constant current source outputs a feedback current to the integration circuit; Before the microprocessor obtains the first integrated voltage output by the integration circuit, the method further includes: outputting a feedback signal to an output terminal of the integration circuit to add a bias voltage to the first integration voltage to obtain a second integration voltage; The voltage interval includes: an upper threshold interval and a lower threshold interval, wherein a voltage interval higher than the bias voltage is the upper threshold interval, and a voltage interval lower than the bias voltage is the lower threshold interval, and both the upper threshold interval and the lower threshold interval are in a positive voltage interval; When a negative input current is input to the integration circuit, the second integration voltage is located in the upper threshold range; When the integration circuit inputs a forward input current, the second integration voltage is located in the lower threshold range.

4. The current-frequency conversion method according to claim 3, wherein: After the constant current source outputs the feedback current to the integration circuit, the method further includes: when the second integration voltage is lower than the lower threshold interval or higher than the upper threshold interval, clearing the number of the pulse signals.

5. The current-frequency conversion method according to claim 3, characterized in that: The method specifically includes: When the number of the pulse signals does not reach the preset value and the input current obtained by the integration circuit changes linearly, the number of the pulse signals is the difference between the number of pulse signals corresponding to the voltage interval in which the second integrated voltage obtained this time is located and the number of pulse signals corresponding to the voltage interval in which the second integrated voltage obtained last time is located; When the number of the pulse signals does not reach the preset value and the input current is commutated, the number of the pulse signals is the difference between the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained last time and the number of pulse signals corresponding to the voltage interval of the second integral voltage obtained this time.

6. A current-frequency conversion system, characterized in that: include: A clock circuit, a temperature compensation circuit, an output circuit, and a current-frequency conversion circuit as described in any one of claims 1 to 2, wherein the current-frequency conversion circuit receives a current signal output by an accelerometer and converts it into a pulse signal, the temperature compensation circuit performs temperature compensation on the current-frequency conversion circuit, the clock circuit provides a clock signal for the current-frequency conversion circuit, and the output circuit increases the driving current for the current-frequency conversion circuit.

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