CN209280808U - A kind of resistance measuring circuit and environmental parameter measuring device - Google Patents
A kind of resistance measuring circuit and environmental parameter measuring device Download PDFInfo
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- CN209280808U CN209280808U CN201821655207.2U CN201821655207U CN209280808U CN 209280808 U CN209280808 U CN 209280808U CN 201821655207 U CN201821655207 U CN 201821655207U CN 209280808 U CN209280808 U CN 209280808U
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Abstract
The utility model embodiment is related to sensor technical field, discloses a kind of resistance measuring circuit and environmental parameter measuring device.Wherein, resistance measuring circuit includes: testing resistance sub-circuit, for according to testing resistance, output measurement electric current；Charge and discharge electronic circuit, including first capacitor, first capacitor are connect with testing resistance sub-circuit, and first capacitor is used to be charged and discharged according to measurement electric current, output measurement voltage value；Compare sub-circuit, connect with charge and discharge electronic circuit, for exporting the first level signal when first capacitor charging, when first capacitor electric discharge, exports second electrical level signal；Controller, sub-circuit connects compared with, for obtaining the first duration when receiving the first level signal, when receiving second electrical level signal, obtains the second duration, the resistance value of testing resistance is determined according to the first duration and the second duration.In the above manner, the present embodiment can effectively improve the measurement accuracy of the resistance value of sensor.
Description
Technical field
The utility model relates to technical field of sensor measurement, and in particular to a kind of resistance measuring circuit and environmental parameter are surveyed
Measure device.
Background technique
Resistance type sensor is widely used in measuring technique, for example, temperature sensor, humidity sensor, pressure resistance type
Sensor etc. by measuring its resistance value, then can since the resistance value of resistance type sensor changes with the variation of environment
Environmental parameter at that time is measured, for example, temperature, humidity, pressure etc..
The main promising electric resistance partial pressure mode of method of resistance type sensor resistance value is measured, that is, passes through single chip computer measurement sensing
The voltage that the resistance of device is got, to calculate the resistance value of sensor.
Inventor has found during realizing the utility model embodiment, current measurement resistance type sensor resistance value
Method, when the resistance change amount of sensor is smaller, the voltage value got is also very small, single-chip microcontroller can not accurate measurement its change
Change, the resistance value so as to cause the sensor measured has error.
Utility model content
In order to solve the above technical problems, the utility model aim is to provide a kind of resistance measuring circuit and environmental parameter is surveyed
Device is measured, the measurement accuracy of the resistance value of sensor can be effectively improved.
To achieve the goals above, the utility model embodiment discloses following technical solution:
The utility model provides a kind of resistance measuring circuit, for measuring testing resistance, the resistance measuring circuit packet
It includes: testing resistance sub-circuit, for connecting the testing resistance, and according to the testing resistance, output measurement electric current；Charge and discharge
Sub-circuit, including first capacitor, the first capacitor are connect with the testing resistance sub-circuit, and the first capacitor is used for basis
The measurement electric current charges and discharges, and exports measurement voltage value；Compare sub-circuit, connects with the charge and discharge electronic circuit
It connects, in the case where first capacitor charging, the measurement voltage value to be compared with the first preset voltage value, and
The first level signal is exported, in the case where first capacitor electric discharge, by the measurement voltage value and the second preset voltage value
It is compared, and exports second electrical level signal；Controller, sub-circuit connects compared with described, for receiving described first
In the case where level signal, the first duration is obtained, in the case where receiving the second electrical level signal, obtains the second duration,
To determine the resistance value of the testing resistance according to first duration and second duration.
In some embodiments, the testing resistance sub-circuit includes: the first connecting pin, second connection end and the second electricity
Hold；One end of second capacitor is for connecting power supply, the other end ground connection of second capacitor, first connecting pin and institute
One end connection of the second capacitor is stated, the second connection end is connect with the charge and discharge electronic circuit, first connecting pin and institute
Second connection end is stated for connecting the testing resistance.
In some embodiments, the charge and discharge electronic circuit further include: first resistor and first diode；First electricity
One end of resistance is connect with the second connection end, and the other end of the first resistor is grounded by the first capacitor, and described
The first input end of the other end of one resistance sub-circuit also compared with described connects, the anode of the first diode and described the
One end of one resistance connects, the output end connection of the cathode of first diode sub-circuit compared with described.In some implementations
In example, the relatively sub-circuit includes: second resistance, 3rd resistor, the 4th resistance, the 5th resistance and first comparator；It is described
For connecting power supply, the other end of the second resistance is connect with one end of the 3rd resistor, described for one end of second resistance
The other end of 3rd resistor is connect with the cathode of the first diode, and the other end of the second resistance is also electric with the described 4th
One end of resistance connects, and the other end of the 4th resistance is connect with one end of the 5th resistance, the 5th resistance it is another
End ground connection, the first input end of the first comparator are connect with the other end of the first resistor, the first comparator
Second input terminal is connect with one end of the 4th resistance, and the output end of the first comparator is negative with the first diode
Pole connection, the output end of the first comparator are also connect with the controller.
In some embodiments, the resistance measuring circuit further includes shaping sub-circuit；The controller passes through described whole
Shape sub-circuit sub-circuit compared with described connects, and the shaping sub-circuit is used for first level signal and second electricity
Ordinary mail number is filtered, and is exported to the controller.
In some embodiments, the shaping sub-circuit includes: the 6th resistance, the 7th resistance, third capacitor and the second ratio
Compared with device；The first input end of second comparator is grounded, the second input terminal of second comparator electricity compared with described
The output end on road connects, and the output end of second comparator is connect with one end of the 7th resistance, the 7th resistance
The other end is connect with the controller, one end of the 6th resistance for connecting power supply, the other end of the 6th resistance with
One end of 7th resistance connects, and one end of the third capacitor is connect with the other end of the 7th resistance, the third
The other end of capacitor is grounded.
In some embodiments, the shaping sub-circuit further include: optical coupling isolator and the 8th resistance；The light-coupled isolation
The first input end of device is connect with the common connection end of the 6th resistance and second comparator, the optical coupling isolator
Second input end grounding, the first output end of the optical coupling isolator respectively with one end of the 8th resistance, it is described 7th electricity
One end of resistance connects, and the other end of the 8th resistance is for connecting power supply, the second output terminal ground connection of the optical coupling isolator.
The utility model additionally provides a kind of resistance measurement method, for measuring testing resistance, which comprises according to
The testing resistance, output measurement electric current；According to the measurement electric current, first capacitor is charged and discharged, and exports survey
Measure voltage value；In the case where first capacitor charging, the measurement voltage value is compared with the first preset voltage value,
And the first level signal is exported, in the case where first capacitor electric discharge, by the measurement voltage value and the second predeterminated voltage
Value is compared, and exports second electrical level signal；In the case where receiving the first level signal, the first duration is obtained, is being connect
In the case where receiving second electrical level signal, the second duration is obtained, to determine according to first duration and second duration
The resistance value of the testing resistance.
In some embodiments, the resistance that the testing resistance is determined according to first duration and second duration
Value Rs, specifically:Wherein, R1、K1、K2For constant, t1For the first duration, t2For the second duration.
The utility model additionally provides a kind of environmental parameter measuring device, surveys including resistance type sensor and above-mentioned resistance
Circuit is measured, the resistance type sensor is connect with the resistance measuring circuit.
The beneficial effect of the utility model embodiment is: being in contrast to the prior art down, the utility model embodiment
A kind of resistance measuring circuit provided measures the charging time and discharge time of charge and discharge electronic circuit by controller, to calculate
The resistance value of testing resistance controls charging process without single-chip microcontroller, and the time precision detected is high, passes so as to effectively improve
The measurement accuracy of the resistance value of sensor.
Detailed description of the invention
One or more embodiments are illustrated by the picture in corresponding attached drawing, these exemplary theorys
The bright restriction not constituted to embodiment, the element in attached drawing with same reference numbers label are expressed as similar element, remove
Non- to have special statement, composition does not limit the figure in attached drawing.
Fig. 1 is the structural schematic diagram of resistance measuring circuit provided by the embodiment of the utility model；
Fig. 2 is the structural schematic diagram of the resistance measuring circuit of Fig. 1；
Fig. 3 is another structural schematic diagram of the resistance measuring circuit of Fig. 1；
Fig. 4 is the flow diagram of resistance measurement method provided by the embodiment of the utility model；
Fig. 5 is the structural schematic diagram of environmental parameter measuring device provided by the embodiment of the utility model.
Specific embodiment
It is practical new below in conjunction with this to keep the objectives, technical solutions, and advantages of the embodiments of the present invention clearer
Attached drawing in type embodiment, the technical scheme in the utility model embodiment is clearly and completely described, it is clear that is retouched
The embodiment stated is the utility model a part of the embodiment, instead of all the embodiments.Based on the implementation in the utility model
Example, every other embodiment obtained by those of ordinary skill in the art without making creative efforts belong to
The range of the utility model protection.
As long as in addition, technical characteristic involved in the various embodiments of the present invention described below each other it
Between do not constitute conflict and can be combined with each other.
Existing many sensors are all resistance type sensors, for example, temperature sensor, humidity sensor, pressure resistance type
Pressure sensor etc., the resistance value of the resistance of these sensors are changed with environment and working condition, by measuring its electricity
Resistance value can then obtain environmental parameter at that time, for example, temperature, humidity, pressure etc..
The method of current measuring resistor type sensor resistance mainly has: electric resistance partial pressure mode passes through single chip computer measurement
The voltage that the resistance of sensor is got, to calculate the resistance value of sensor.
But since the change in resistance of resistance type sensor is not line style variation, and variation range is big, hinders from several hundred Europe
Value changes to several hundred kilo-ohms.And the resistance value of divider resistance R1 can only be a fixed value, in this way when the resistance value of sensor much
When resistance value greater than divider resistance R1 or when the resistance value of sensor is far smaller than the resistance value of divider resistance R1, at this moment sensor
Resistance variable quantity it is smaller when, the voltage value V1 got is also very small, cause single-chip microcontroller that can not detect other variations, from
And the sensor resistance resistance value that detected is caused to have error；Also, the confession of the power supply due to bleeder circuit and monolithic machine testing
Electricity must be same power supply power supply, when requiring sensor power supply to power using the isolated power supply of safety due to security reason,
The method of light-coupled isolation can not be directlyed adopt to solve, can only in addition increase single-chip microcontroller control and communicating circuit realize safety every
From power supply plan, to increase cost needs.
Based on this, the utility model embodiment provides a kind of resistance measuring circuit, method and environmental parameter measuring device, adopts
Resistance is calculated with the method for calculating the charge and discharge time, charge and discharge process is automatically performed by hardware circuit, and charge and discharge are cut
Only voltage is constant, and the length of time is directly proportional with resistance, detected by single-chip microcontroller, fills without single-chip microcontroller control
Electric process, the time precision that detects is high, so as to effectively improve sensor resistance value measurement accuracy.
The resistance measuring circuit of the utility model embodiment can be used as one of functional unit, be independently arranged at environment
In parameter measuring apparatus, can also be used as be integrated into a functional module carry out using.
Specifically, with reference to the accompanying drawing, the utility model embodiment is further elaborated.
Fig. 1 is the structural schematic diagram of resistance measuring circuit provided by the embodiment of the utility model.As shown in Figure 1, resistance is surveyed
Amount circuit 100 includes testing resistance sub-circuit 110, charge and discharge electronics electricity for measuring testing resistance 200, resistance measuring circuit 100
Sub-circuit 130, shaping sub-circuit 140 and controller 150 are compared in road 120.
Wherein, testing resistance sub-circuit 110 is for connecting testing resistance 200, and charge and discharge electronic circuit 120 and testing resistance are extremely
Circuit 110 connect, compare sub-circuit 130 and connect with charge and discharge electronic circuit 120, controller 150 pass through shaping sub-circuit 140 and than
It is connected compared with sub-circuit 130.Testing resistance sub-circuit 110 is used for according to testing resistance 200, output measurement electric current；Charge and discharge electronics electricity
Road 120 is used for the measurement electric current exported according to testing resistance sub-circuit 110, charges and discharges, and export measurement voltage value；
Compare sub-circuit 130 for when charging, measurement voltage value being compared with the first preset voltage value, and export the first level
Measurement voltage value is compared, and export second electrical level signal by signal with the second preset voltage value upon discharging；Shaping
Circuit 140 is exported for being filtered to the first level signal and second electrical level signal to controller 140；Controller 140 is used
In when receiving the first level signal, the first duration is obtained, when receiving second electrical level signal, obtains the second duration, from
And the resistance value of testing resistance 200 is determined according to the first duration and the second duration.
It should be noted that testing resistance 200 can for resistance value can be changed resistance (such as resistance type sensor etc.) or
The constant resistance of person's resistance value, in the present embodiment, testing resistance 200 be resistance type sensor, the both ends of testing resistance 200 with to
Measuring resistance sub-circuit 110 connects, thus when the change in resistance of testing resistance 200, the measurement of the output of testing resistance sub-circuit 110
Electric current also corresponding change.
In the present embodiment, when resistance measuring circuit 100 measures the charging of charge and discharge electronic circuit 120 by controller 150
Between and discharge time control charging process, the time detected without single-chip microcontroller to calculate the resistance value of testing resistance 200
Precision is high, so as to effectively improve sensor resistance value measurement accuracy.
Specifically, referring to Fig. 2, testing resistance sub-circuit 110 includes the first connecting pin J1, second connection end J2 and second
Capacitor C2.Wherein, one end of the second capacitor C2 is for connecting power Vcc, the other end ground connection of the second capacitor C2, the first connecting pin
J1 is connect with one end of the second capacitor C2, and second connection end J2 is connect with the input terminal of charge and discharge electronic circuit 120, the first connecting pin
J1 and second connection end J2 is for connecting testing resistance 200.
Wherein, the first connecting pin J1 and second connection end J2 can be produced in the same shell, as a connecting pin
Mouthful, testing resistance 200 is connect with connectivity port, so that the both ends of testing resistance 200 are connect with the first connecting pin J1, second respectively
Hold J2 connection.
In the present embodiment, power Vcc output electric current passes sequentially through the first connecting pin J1, testing resistance 200, second connects
J2 is held, to export measurement electric current to charge and discharge electronic current 120.When the resistance value of testing resistance 200 changes, the big of electric current is measured
Small also corresponding change.
Charge and discharge electronic circuit 120 includes first capacitor C1, first resistor R1 and first diode D1.Wherein, first resistor
One end of R1 is connect with second connection end J2, and the other end of first resistor R1 is grounded by first capacitor C1, first resistor R1's
The first input end of other end sub-circuit 130 also compared with connects, one end of the anode and first resistor R1 of first diode D1
Connection, the output end connection of the cathode of first diode D1 sub-circuit 130 compared with.
In the present embodiment, measurement electric current charges to first capacitor C1 after flowing through first resistor R1, works as first capacitor
At the end of C1 charges, first capacitor C1 flows into the output for comparing sub-circuit 130 after first resistor R1, first diode D1
End, to discharge, the other end of first resistor R1 exports the measurement voltage value measured in first capacitor C1 to more sub
The first input end of circuit 130.
Comparing sub-circuit 130 includes second resistance R2,3rd resistor R3, the 4th resistance R4, the ratio of the 5th resistance R5 and first
Compared with device U1A.Wherein, one end of second resistance R2 is for connecting power Vcc, and the other end of second resistance R2 is with 3rd resistor R3's
One end connection, the other end of 3rd resistor R3 connect with the cathode of first diode D1, and the other end of second resistance R2 is also with the
One end of four resistance R4 connects, and the other end of the 4th resistance R4 is connect with one end of the 5th resistance R5, and the 5th resistance R5's is another
End ground connection, the first input end of first comparator U1A are connect with the other end of first resistor R1, and the second of first comparator U1A
Input terminal is connect with one end of the 4th resistance R4, and the output end of first comparator U1A is connect with the cathode of first diode D1, the
The output end of one comparator U1A also passes through shaping sub-circuit 140 and connect with controller 150.
Wherein, first comparator U1A can be identified the chip compared with for LM393 etc. to input signal.?
In the present embodiment, as shown in Fig. 2, the 6th pin of first comparator U1A be first comparator U1A first input end (reverse phase is defeated
Enter end), the 5th pin of first comparator U1A is the second input terminal (non-inverting input terminal) of first comparator U1A, and first compares
The 7th pin of device U1A is the output end of first comparator U1A, the 4th pin ground connection of first comparator U1A, first comparator
The 8th pin of U1A connects power Vcc.
In the present embodiment, when the voltage value of the second input terminal of first comparator U1A is higher than the voltage of first input end
When value, the output end of first comparator U1A is open-drain high-impedance state；When the voltage value of the second input terminal of first comparator U1A
Lower than first input end voltage value when, the output end of first comparator U1A is low level.
Therefore, when the output end of first comparator U1A is open-drain high-impedance state, the second input of first comparator U1A
End is divided by the 4th resistance R4 and the 5th resistance R5 and second resistance R2, obtains the first preset voltage value V1, have:
Wherein, R2、R4、R5Respectively second resistance, the resistance value of the 4th resistance and the 5th resistance, VccFor the voltage value of power supply.
When the output end of first comparator U1A is low level, due to the output of 3rd resistor R3 and first comparator U1A
End connection, the second input terminal of first comparator U1A is in parallel with 3rd resistor R3 by the 4th resistance R4 and the 5th resistance R5 at this time
It is divided again with second resistance R2 afterwards, obtains the second preset voltage value V2, have:
Wherein, R2、R3、R4、R5Respectively second resistance, 3rd resistor, the resistance value of the 4th resistance and the 5th resistance, VccFor
The voltage value of power supply.
It is worth noting that, second resistance, 3rd resistor, the 4th resistance and the 5th resistance are fixed value resistance, voltage vcc
Voltage value constant, then the first preset voltage value V1With the second preset voltage value V2Also constant.
Shaping sub-circuit 140 includes the 6th resistance R6, the 7th resistance R7, third capacitor C3 and the second comparator U1B.Its
In, the first input end of the second comparator U1B is grounded, the second input terminal of the second comparator U1B compared with sub-circuit 130 it is defeated
Outlet connection, the output end of the second comparator U1B are connect with one end of the 7th resistance R7, the other end of the 7th resistance R7 and control
Device 150 connects, and one end of the 6th resistance R6 connects for connecting power supply, the other end of the 6th resistance R6 and one end of the 7th resistance R7
It connects, one end of third capacitor C3 is connect with the other end of the 7th resistance R7, the other end ground connection of third capacitor C3.
Wherein, the output end connection of the second input terminal sub-circuit 130 compared with of the second comparator U1B, specifically: second
The second input terminal of comparator U1B is connect with the output end of first comparator U1A.
Wherein, the first input end ground connection of the second comparator U1B, specifically: the first input end of the second comparator U1B connects
The other end for meeting the 4th resistance R4 is grounded by the 5th resistance R5.
Wherein, the second comparator U1B can carry out the chip of shaping filter for LM393 etc. to input signal.At this
In embodiment, as shown in Fig. 2, the 2nd pin of the second comparator U1B is the first input end (anti-phase input of the second comparator U1B
End), the 3rd pin of the second comparator U1B is the second input terminal (non-inverting input terminal) of the second comparator U1B, the second comparator
The 1st pin of U1B is the output end of the second comparator U1B, the 4th pin ground connection of the second comparator U1B, the second comparator U1B
The 8th pin connect power Vcc.
In the present embodiment, waveform that sub-circuit 130 exports (including first will be compared by setting shaping sub-circuit 140
Level signal and second electrical level signal) shaping is carried out, the rectangular wave of standard can be obtained.
Optionally, in some other embodiments, in order to improve the safety of resistance measuring circuit, as shown in figure 3, shaping
Sub-circuit 140 further includes optical coupling isolator U2 and the 8th resistance R8.Wherein, the first input end of optical coupling isolator U2 and the 6th electricity
Hinder the common connection end connection of R6 and the second comparator U1B, the second input end grounding of optical coupling isolator U2, optical coupling isolator U2
The first output end connect respectively with one end of one end of the 8th resistance R8, the 7th resistance R7, the other end of the 8th resistance R8 is used
In connection power supply, the second output terminal ground connection of optical coupling isolator U2.Waveform signal, energy are propagated by setting optical coupling isolator U2
It is enough to be powered in the two sides of optical coupling isolator U2 using different power supplys, for example, testing resistance side it is safe and reliable every
From power supply power supply, effect of the isolation safe power supply power supply without additionally increasing protective device can be realized.
Controller 150 can be include processor, with control processing function specific integrated circuit (Application-
Specific Integrated Circuit, ASIC), field-programmable gate array (Field Programmable Gate
Array, FPGA), single-chip microcontroller etc..In the present embodiment, controller 150 be single-chip microcontroller, the input and output pin of controller 150 with
The output end (i.e. the other end of the 7th resistance R7) of shaping sub-circuit 140 connects.Controller 150 is used for: sub when receiving shaping
When the first level signal that circuit 140 exports, the first duration is obtained, when the second electrical level for receiving the output of shaping sub-circuit 140
When signal, the second duration is obtained, to determine the resistance value of testing resistance 200 according to the first duration and the second duration.
Wherein, the signal that shaping sub-circuit 140 exports is the rectangular wave by shaping, includes the first level signal and second
Level signal, in the present embodiment, the first level signal are high level signal, and second electrical level signal is low level signal.First
Shi Changwei the first level signal duration length in one cycle, second when a length of second electrical level within the same period
Signal duration length.Controller 150 starts to calculate the first duration, when receiving when receiving the first level signal
When second electrical level signal, the first duration calculation terminates and triggers to calculate the second duration, when receiving the first level signal again, the
Two duration calculations terminate and trigger to recalculate the first duration, constantly repeat.Controller 150 is according to first in the same period
Duration and the second duration calculation go out the resistance value of testing resistance 200.
It is understood that shaping sub-circuit 140 can be omitted in some other embodiments, first comparator U1A's
Output end is directly connect with controller 150, and controller 150 is believed by receiving the waveform of the output end output of first comparator U1A
Number, and the first duration and second duration are obtained, so that it is determined that the resistance value of testing resistance 200.
In the present embodiment, the course of work of resistance measuring circuit 100 is substantially are as follows: when to first capacitor C1 primary charging
When, since the voltage on first capacitor C1 is 0V, the voltage value of the second input terminal of first comparator U1A is greater than first comparator
The output end of the measurement voltage value of the first input end of U1A, first comparator U1A is open-drain high-impedance state, and first compares at this time
The voltage value of the second input terminal of device U1A is the first preset voltage value；Power Vcc power supply, measurement electric current pass through testing resistance 200
It charges with first resistor R1 to first capacitor C1, the measurement voltage value of first capacitor C1 constantly rises, when measurement voltage value reaches
When the first preset voltage value, the output end of first comparator U1A exports low level, then first capacitor C1 charging terminates, the first electricity
Hold C1 to start to discharge.
When first capacitor C1 electric discharge, since the output end of first comparator U1A exports low level, then first comparator
The voltage value of the second input terminal of U1A is the second preset voltage value, and discharge current is flowed by first resistor R1, first diode D1
Entering the output end of first comparator U1A, measurement voltage value declines, when measurement voltage value drops to the second preset voltage value, the
The output end of one comparator U1A is open-drain high-impedance state, and first capacitor C1 continues to put without the output end of normal direction first comparator U1A
Electricity, then the discharge process of first capacitor C1 terminates, and first capacitor C1 charges again.
When first capacitor C1 charges again, the output end of first comparator U1A is open-drain high-impedance state, at this point, first
The voltage value of the second input terminal of comparator U1A is the first preset voltage value, measures voltage value since the second preset voltage value
Rise, when measurement voltage value reaches the first preset voltage value, the output end of first comparator U1A exports low level, the first electricity
Holding C1 charging terminates, and first capacitor C1 starts to discharge ... repeatedly, into stable oscillatory regime, by shaping sub-circuit
After 140 shaping, controller 150 receives stable rectangular wave.
The resistance value of testing resistance is determined according to the first duration and the second duration, specifically:
First duration
Second duration
Wherein, Rs、R1Respectively testing resistance, first resistor resistance value, C2For the capacitance of the second capacitor, V1、V2Respectively
For the first preset voltage value, the second preset voltage value, VccFor supply voltage value, VF-D1For the forward voltage drop of first diode D1.
It is assumed thatThen K1、K2For steady state value, then
I.e.
By the first duration t1, the second duration t2Value substitute into above-mentioned formula, then the resistance value of testing resistance 200 can be obtained.
In the present embodiment, resistance measuring circuit 100 is charged and discharged by charge and discharge electronic circuit 120, and output is surveyed
Amount voltage value is compared with the first preset voltage value and the second preset voltage value, exports the first level signal and the second electricity respectively
Ordinary mail number, controller 150 obtain the first level signal the first duration and second electrical level signal the second duration, thus calculate to
The resistance value of measuring resistance, hardware circuit carry out charge and discharge automatically, generate charge cutoff voltage and discharge cut-off voltage, are not necessarily to single-chip microcontroller
Charging process is controlled, the time precision detected is high, and the data detected are unrelated with the precision of capacitor, so as to effectively mention
The measurement accuracy of the resistance value of high sensor.
Fig. 4 is the flow diagram of resistance measurement method provided by the embodiment of the utility model.As shown in figure 4, the resistance
Measurement method is applied to the resistance measuring circuit 100 of above-described embodiment, and resistance measuring circuit 100 is used to measure testing resistance 200,
The resistance measurement method includes:
310, according to the testing resistance, output measurement electric current；
320, it according to the measurement electric current, charges and discharges, and exports measurement voltage value；
330, the measurement voltage value is compared with the first preset voltage value when charging, and exports the first level
The measurement voltage value is compared, and export second electrical level signal by signal with the second preset voltage value upon discharging；
340, when receiving the first level signal, the first duration is obtained, when receiving second electrical level signal, obtains the
Two durations, to determine the resistance value of the testing resistance according to first duration and second duration.
Wherein, the resistance value of the testing resistance is determined according to first duration and second duration, specifically:
The resistance value of testing resistance is calculated, has:
Wherein, R1、K1、K2For constant, t1For the first duration, t2For the second duration.
The above method can be applied to resistance measuring circuit 100 provided by the utility model embodiment, have resistance measurement
The beneficial effect of circuit.The not technical detail of detailed description in the present embodiment, reference can be made to the utility model embodiment is provided
Resistance measuring circuit.
Fig. 5 is the structural schematic diagram of environmental parameter measuring device provided by the embodiment of the utility model.As shown in figure 5, should
Environmental parameter measuring device 400 includes resistance type sensor 410 and resistance measuring circuit 100, resistance type sensor 410 and resistance
Measuring circuit 100 connects.
Wherein, resistance measuring circuit 100 is identical as in examples detailed above, and details are not described herein again.
Wherein, resistance type sensor 410 can be used for the biography of measure annular parameter for temperature sensor, humidity sensor etc.
Sensor.
Optionally, which can also include control module 420, and control module 420 receives resistance
The environmental parameter that measuring circuit 100 measures, and according to the environmental parameter, carry out control work.
Environmental parameter measuring device 400 in the present embodiment includes the high resistance measuring circuit 100 of measurement accuracy, so as to
The measurement accuracy of the resistance value of sensor is enough effectively improved, and then mentions high control precision.
Finally, it should be noted that above embodiments are only to illustrate the technical solution of the utility model, rather than its limitations；
Under the thinking of the utility model, it can also be combined between the technical characteristic in above embodiments or different embodiments,
Step can be realized with random order, and there are many other variations of the different aspect of the utility model as described above, be
Simplicity, they do not provide in details；Although the utility model is described in detail with reference to the foregoing embodiments, this
The those of ordinary skill in field it is understood that it is still possible to modify the technical solutions described in the foregoing embodiments,
Or equivalent replacement of some of the technical features；And these are modified or replaceed, and do not make the sheet of corresponding technical solution
Matter departs from the scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. a kind of resistance measuring circuit, which is characterized in that for measuring testing resistance, the resistance measuring circuit includes:
Testing resistance sub-circuit, for connecting the testing resistance, and according to the testing resistance, output measurement electric current；
Charge and discharge electronic circuit, including first capacitor, the first capacitor are connect with the testing resistance sub-circuit, first electricity
Hold for being charged and discharged according to the measurement electric current, and exports measurement voltage value；
Compare sub-circuit, connect with the charge and discharge electronic circuit, is used in the case where first capacitor charging, by the survey
Amount voltage value is compared with the first preset voltage value, and exports the first level signal, the case where the first capacitor is discharged
Under, the measurement voltage value is compared with the second preset voltage value, and export second electrical level signal；
Controller, sub-circuit connects compared with described, for obtaining first in the case where receiving first level signal
Duration obtains the second duration in the case where receiving the second electrical level signal, thus according to first duration and described
Second duration determines the resistance value of the testing resistance.
2. resistance measuring circuit according to claim 1, which is characterized in that the testing resistance sub-circuit includes: first
Connecting pin, second connection end and the second capacitor；
One end of second capacitor is for connecting power supply, the other end ground connection of second capacitor, first connecting pin with
One end of second capacitor connects, and the second connection end is connect with the charge and discharge electronic circuit, first connecting pin with
The second connection end is for connecting the testing resistance.
3. resistance measuring circuit according to claim 2, which is characterized in that the charge and discharge electronic circuit further include: first
Resistance and first diode；
One end of the first resistor is connect with the second connection end, and the other end of the first resistor passes through first electricity
Hold ground connection, the first input end connection of the other end of first resistor sub-circuit also compared with described, the first diode
Anode connect with one end of the first resistor, the output end of the cathode of first diode sub-circuit compared with described company
It connects.
4. resistance measuring circuit according to claim 3, which is characterized in that it is described relatively sub-circuit include: second resistance,
3rd resistor, the 4th resistance, the 5th resistance and first comparator；
One end of the second resistance is for connecting power supply, one end company of the other end of the second resistance and the 3rd resistor
Connect, the other end of the 3rd resistor is connect with the cathode of the first diode, the other end of the second resistance also with institute
One end connection of the 4th resistance is stated, the other end of the 4th resistance is connect with one end of the 5th resistance, the 5th electricity
The other end of resistance is grounded, and the first input end of the first comparator is connect with the other end of the first resistor, and described first
Second input terminal of comparator is connect with one end of the 4th resistance, the output end of the first comparator and the described 1st
The cathode of pole pipe connects, and the output end of the first comparator is also connect with the controller.
5. resistance measuring circuit according to claim 1-4, which is characterized in that the resistance measuring circuit also wraps
Include shaping sub-circuit；
By the shaping sub-circuit, the sub-circuit compared with described connects the controller, and the shaping sub-circuit is used for described
First level signal and the second electrical level signal are filtered, and are exported to the controller.
6. resistance measuring circuit according to claim 5, which is characterized in that the shaping sub-circuit include: the 6th resistance,
7th resistance, third capacitor and the second comparator；
The first input end of second comparator is grounded, the second input terminal of second comparator sub-circuit compared with described
Output end connection, the output end of second comparator connect with one end of the 7th resistance, the 7th resistance it is another
One end is connect with the controller, and one end of the 6th resistance is for connecting power supply, the other end of the 6th resistance and institute
One end connection of the 7th resistance is stated, one end of the third capacitor is connect with the other end of the 7th resistance, the third electricity
The other end of appearance is grounded.
7. resistance measuring circuit according to claim 6, which is characterized in that the shaping sub-circuit further include: optocoupler every
From device and the 8th resistance；
The first input end of the optical coupling isolator is connect with the common connection end of the 6th resistance and second comparator,
Second input end grounding of the optical coupling isolator, the first output end of the optical coupling isolator respectively with the 8th resistance
One end connection of one end, the 7th resistance, the other end of the 8th resistance are used to connect power supply, the optical coupling isolator
Second output terminal ground connection.
8. a kind of environmental parameter measuring device, which is characterized in that including described in resistance type sensor and claim any one of 1-7
Resistance measuring circuit, the resistance type sensor connect with the resistance measuring circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821655207.2U CN209280808U (en) | 2018-10-11 | 2018-10-11 | A kind of resistance measuring circuit and environmental parameter measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821655207.2U CN209280808U (en) | 2018-10-11 | 2018-10-11 | A kind of resistance measuring circuit and environmental parameter measuring device |
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| Publication Number | Publication Date |
|---|---|
| CN209280808U true CN209280808U (en) | 2019-08-20 |
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|---|---|---|---|
| CN201821655207.2U Withdrawn - After Issue CN209280808U (en) | 2018-10-11 | 2018-10-11 | A kind of resistance measuring circuit and environmental parameter measuring device |
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| CN (1) | CN209280808U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109188095A (en) * | 2018-10-11 | 2019-01-11 | 深圳和而泰智能控制股份有限公司 | A kind of resistance measuring circuit, method and environmental parameter measuring device |
| CN109188095B (en) * | 2018-10-11 | 2024-05-17 | 深圳和而泰智能控制股份有限公司 | Resistance measurement circuit, method and environment parameter measurement device |
-
2018
- 2018-10-11 CN CN201821655207.2U patent/CN209280808U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109188095A (en) * | 2018-10-11 | 2019-01-11 | 深圳和而泰智能控制股份有限公司 | A kind of resistance measuring circuit, method and environmental parameter measuring device |
| CN109188095B (en) * | 2018-10-11 | 2024-05-17 | 深圳和而泰智能控制股份有限公司 | Resistance measurement circuit, method and environment parameter measurement device |
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