CN109490614A - One kind being based on the adjustable digital galvanometer of STM32 range - Google Patents

One kind being based on the adjustable digital galvanometer of STM32 range Download PDF

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Publication number
CN109490614A
CN109490614A CN201811512738.0A CN201811512738A CN109490614A CN 109490614 A CN109490614 A CN 109490614A CN 201811512738 A CN201811512738 A CN 201811512738A CN 109490614 A CN109490614 A CN 109490614A
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CN
China
Prior art keywords
circuit
digital
stm32
range
signal
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Pending
Application number
CN201811512738.0A
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Chinese (zh)
Inventor
刘晓瑜
孙晶华
李俊东
王峰
姜富强
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Harbin Engineering University
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Harbin Engineering University
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Priority to CN201811512738.0A priority Critical patent/CN109490614A/en
Publication of CN109490614A publication Critical patent/CN109490614A/en
Pending legal-status Critical Current

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques

Abstract

The invention belongs to DC detecting instrument fields, and in particular to a kind of measurable low current signal based on the adjustable digital galvanometer of STM32 range.The present invention includes range switching and input protection circuit, signal conditioning circuit, A/D conversion circuit, STM32 control circuit and TFT screen driving circuit, power circuit.The digital galvanometer, utilize the IIR low-pass filter of design, output signal filtering to high-resolution bipolarity analog-to-digital conversion, analog-digital converter cooperates STM32 to complete digital collection, TFT screen pointer is completed by driving circuit again to show and digital-scroll technique, the precision of low current signal detection is improved, convenient for users to reading data;It since range is changeable and digital pointer show, reduces since tested electric current is excessive, leads to the risk of galvanometer damage, strong antijamming capability and easy to operate is low in cost, easy to spread.

Description

One kind being based on the adjustable digital galvanometer of STM32 range
Technical field
The invention belongs to DC detecting instrument fields, and in particular to a kind of measurable low current signal based on STM32 The adjustable digital galvanometer of range.
Background technique
For weak current military surveillance, physics, chemistry, electrochemistry, biomedicine, astronomy, learn, magnetic Etc. many fields, which have, to be widely applied.However, current tradition machinery needle galvanometer can not automatic switching range, Bu Nengshi Now fluctuate the detection function of biggish current signal.Tradition machinery needle galvanometer in the detection, since power selected Big or operation error, can make excessive by galvanometric electric current, exceed original range, pointer is caused to deflect rapidly, or even go out Existing pointer mechanical injuries, influence the progress of test experience.Meanwhile traditional eedle galvanometer is once by the slight of the external world Vibration, will cause the swing of pointer, be easy by extraneous interference, bring great inconvenience to data are read, influence to read Several accuracys.Therefore, at this stage for weak current, although traditional eedle galvanometer sensitivity is very high, But no matter for the operating experience of the progress of the maintenance of instrument or detection and user, all there are many unfavorable shadows It rings.
Summary of the invention
It is an object of the invention to solve tradition machinery needle galvanometer can not automatic switching range, be easy to appear pointer machine The problems such as tool damages, is easy by extraneous interference, provides one kind and is based on the adjustable digital galvanometer of STM32 range, can be certainly Dynamic switching range indicates that range is ± 2.5uA by TFT screen pointer, can estimate and read 2 significant digits;Digital-scroll technique amount Journey is ± 2.500mA, can be differentiated to 1uA, range warning and digital zeroing function is provided simultaneously with, to complete to low current signal Detection.
The object of the present invention is achieved like this:
One kind being based on the adjustable digital galvanometer of STM32 range, including range switching and input protection circuit, signal condition Circuit, A/D conversion are analog to digital conversion circuit, STM32 control circuit and TFT display drive circuit and power circuit;It is described The low current signal of input is converted into voltage signal and exported to signal conditioning circuit by range switching and input protection circuit;Institute It states signal conditioning circuit and filtering is amplified to voltage signal, and filtered analog voltage signal will be amplified and exported to modulus turn Change circuit;The analog voltage signal of input is converted to digital signal and exports by analog-digital conversion circuit as described gives STM32 control circuit; The STM32 control circuit is handled and is calculated to digital signal, and calculated result is exported and drives electricity to TFT display screen Road;The TFT display drive circuit shows calculated result;The power circuit switches with range respectively and inputs guarantor Protection circuit, signal conditioning circuit, analog to digital conversion circuit, STM32 control circuit are connected with TFT display drive circuit, supply for it Electricity.
The range switch circuit includes optical coupled switch circuit and I/V conversion i.e. current/voltage converter circuit;Range switching The switch of optocoupler is controlled, by driven by program STM32 to control whether parallel resistance is incorporated to circuit and then control access electricity The resistance value on road is completed.
The input protection circuit by two precision resistance both ends, two reversed fast switching diodes in parallel into Row overcurrent protection.
The STM32 control circuit is digital trap, number by control programs implementing data low-pass filter filtering The digital signal that analog to digital conversion circuit exports is filtered by trapper.
The STM32 control circuit completes digital zero setting by control button driver.
The STM32 control circuit is completed Digital Signal Processing by program and is calculated, and the reading of current signal is obtained.
The TFT display screen shows the reading of current signal in the form of pointer and charactron are two different.
The beneficial effects of the present invention are:
1. having the function of automatic switching range, it is in the form of simulated pointer and charactron TFT display screen respectively It is existing.
2. automatic range switching expands the range of tested current signal, clear reading is easy to use.It is accused with outranging Alert function is effectively avoided due to misoperation or pointer mechanical injuries caused by outranging use, and then can not normal work Make the generation of phenomenon.
3. numerical indexes indicate that range is ± 2.5uA, it can estimate and read 2 significant digits;Digital-scroll technique range be ± The method that 2.500mA can be differentiated to 1uA, while be combined using high-resolution bipolarity analog-to-digital conversion with digital trap AD acquisition is completed, so that measurement result precision is high, stability is good, strong antijamming capability.
4. the configuration of the present invention is simple, low in cost, easy to spread.
Detailed description of the invention
Fig. 1 is the principle of the present invention block diagram;
Fig. 2 is the flow chart of the implementation method and implementation of 50Hz digital trap;
Fig. 3 be range switch circuit of the invention, signal conditioning circuit, A/D converter circuit schematic diagram;
Fig. 4 is the schematic diagram of STM32 control circuit of the invention and FTF screen driving circuit;
Fig. 5 is the schematic diagram of power circuit of the invention;
Fig. 6 is the working interface figure that TFT display screen of the present invention is shown.
Specific embodiment
Following further describes the present invention with reference to the drawings:
One kind being based on the adjustable digital galvanometer of STM32 range, including preposition amplification and filter circuit, high-resolution pair Polarity analog to digital conversion circuit, STM32 control circuit are connected with TFT screen driving circuit;Power circuit respectively with preposition amplification and filter Wave circuit, high-resolution bipolarity analog to digital conversion circuit, STM32 control circuit are connected with TFT screen driving circuit.The present invention is logical Cross the emulation of matlab software realization 50Hz trapper, then by program realize 50Hz wave digital lowpass filter filter function and TFT display screen simulated pointer and digital display function.
The function that the preposition amplification and filter circuit are realized mainly includes I/V conversion, range switching, input protection and puts Big filtering.
The preposition amplification and filter circuit are connected with high-resolution bipolarity analog to digital conversion circuit;The amplifier type of use Number be INA188.
The high-resolution bipolarity analog to digital conversion circuit is connected with STM32 control circuit;Use 18 high-precision moulds Number converter, model ADS8699.
The 50Hz digital trap is to be filtered the collected digital signal of AD, is not filtered with eliminating by analog circuit The higher frequency signals fallen.
The STM32 control circuit is connected with TFT screen driving circuit;The chip model that control circuit uses for STM32F103RET6。
The preposition amplification and filter circuit complete the function of amplification and filtering to input small-signal.It is described preposition Amplification and filter circuit and high-resolution bipolarity analog to digital conversion circuit and STM32 control circuit and TFT screen driving circuit pair Voltage signal that conditioning circuit is exported carries out digital collection and image is shown, then by realizing faint letter to writing for program Number digital filtering and different ranges under low current signal in TFT screen respectively in the form of pointer and charactron are two different The function of presentation.
The power circuit is completed to the function of each module for power supply.
Referring to Fig.1, the present invention include range switching with input protection circuit, signal conditioning circuit, A/D conversion circuit, STM32 control circuit and TFT display drive circuit and power circuit.Range switch circuit includes optical coupled switch circuit and I/ V conversion circuit.Signal conditioning circuit includes amplifying circuit and filter circuit.A/D converter circuit connects STM32 control circuit.Power supply Circuit is separately connected range and input protection circuit, signal conditioning circuit, A/D converter circuit, STM32 control circuit and TFT screen drive Dynamic circuit.
The function of the automatic range switching is the switch by driven by program STM32 by control optocoupler, to control Whether parallel resistance processed is incorporated to circuit to realize;By being write to internal processes, realize presented on TFT screen pointer and Two kinds of display patterns of charactron.Meanwhile making AD acquisition more accurate in order to obtain, the present invention carries out emulation using matlab software and sets Filtering of the digital filter of low-pass filtering for AD acquisition signal is counted, realization filter function is write by program.
The range switch circuit controls that whether connecting for parallel resistance controls the change of resistance value by optocoupler, in turn Realize range switching;And input protection circuit is by two precision resistance both ends, two reversed two poles of high-speed switch in parallel Pipe realizes the function of overcurrent protection.The signal conditioning circuit amplifies faint input voltage signal, then to defeated Signal is filtered out.
Referring to Fig. 2, the present invention uses matlab software mould to improve the precision of AD acquisition signal while saving cost Quasi- emulation iir filter.According to design requirement, the present invention selects emulation Butterworth LPF, first to cutoff frequency, The requirement of stop-band frequency, sample frequency, stopband attenuation and ripple is inputted, and estimates minimum filter by buttord function Wave device order and by frequency, carrys out Butterworth low-pass filter by the design of butter function, using freqz function Corresponding frequency conversion is carried out, new function and time domain figure that superpositing function s to the end passes through low-pass filter are obtained, by matlab Simulation result is obtained with C language to compile, the final low-pass filter for realizing 5Hz and 50Hz single-frequency superposition harmonic signal makes defeated Out only containing the purpose of design of 5Hz.
Referring to Fig. 3, range switching and input protection circuit mainly complete the faint current signal of input I/V conversion, The effect of range switching and protection.Input current enters I/V conversion circuit by insurance and switch by J3, then passes through input protection Circuit, the entering signal conditioning circuit in the form of voltage signal.The part is made of differential amplification and passive filtering, times magnification Number is 10.1 times.Amplify output voltage and enter A/D conversion circuit by filtering, to complete the transformation of digital signal, then passes through SPI Digital signal is transmitted to STM32F103RET6 by communication protocol.Join Fig. 4, digital signal completes number in STM32F103RET6 Collected data are passed through TFT screen driving circuit, are presented on TFT screen by signal processing and calculating.
Referring to Fig. 5, it is electric to range swithching circuit, signal condition that power circuit is mainly responsible for converting for low and high level Road, A/D conversion circuit, STM32 control circuit and TFT screen drive circuitry function.Power input 9V passes through Switching Power Supply Chip MAX764 changes into -6V, changes into -5V using linear power supply chip TPS7A301A;9V passes through linear power supply chip LT3042 Change into 5V;± 5V powers to amplifier INA188.Power input 9V changes into 3.3V and 5V by linear power supply chip AMS1117, Middle 5V powers to analog-digital converter ADS8699.Power input 9V changes into 3.3V by switching power source chip TPS54202, gives The power supply of STM32 and TFT display screen.
Referring to Fig. 6, when electric current to be measured is between ± 2.5uA, presented in the form of pointer on a display screen, can estimate read it is small Two after several points;When electric current to be measured be beyond lower range range, then show in digital form on a display screen, range be ± 2.500mA can differentiate 1uA.The present invention carries out modulus by the picture of the design to scale interface, to complete in TFT screen The upper function that scale is presented, while the location of pixels coordinate and pointer starting point location of pixels coordinate of each scale division value point of recording meter panel, With the location of pixels coordinate of scale division value respectively with pointer starting point coordinate, a red pointer is done by program;Finally in order to make to carve Degree display is accurate enough, and by the difference between each minimum division value by transverse and longitudinal coordinate, is divided into 10 parts, is approximately A kind of linear relationship enables simulated pointer very accurately to appear similar to the working condition of mechanical indicator.TFT screen Numeral method is respectively corresponded by the location of pixels coordinate at determining numeral method edge further according to input current value difference Corresponding picture is called in limited area to complete the function of display.
The digital measuring of low current signal may be implemented in the present invention through the above scheme, be provided simultaneously with range swithching, It resets manually, TFT screen pointer shows and facilitates reading data, structure letter with the function of numeral method, instrument precision height List is not easy to be affected by the external environment and be not easy to cause to damage since electric current to be measured is excessive, can be good at meeting to weak current The requirement of detection.

Claims (7)

1. one kind is based on the adjustable digital galvanometer of STM32 range, it is characterised in that: switch including range and input protection electricity Road, signal conditioning circuit, A/D conversion are analog to digital conversion circuit, STM32 control circuit and TFT display drive circuit and electricity Source circuit;The low current signal of input is converted into voltage signal and exported to signal by the range switching and input protection circuit Conditioning circuit;The signal conditioning circuit amplifies filtering to voltage signal, and will amplify filtered analog voltage signal It exports to analog to digital conversion circuit;Analog-digital conversion circuit as described by the analog voltage signal of input be converted to digital signal export to STM32 control circuit;The STM32 control circuit is handled and is calculated to digital signal, and calculated result is exported to TFT Display drive circuit;The TFT display drive circuit shows calculated result;The power circuit respectively with range Switching and input protection circuit, signal conditioning circuit, analog to digital conversion circuit, STM32 control circuit and TFT display drive circuit It is connected, powers for it.
2. according to claim 1 a kind of based on the adjustable digital galvanometer of STM32 range, it is characterised in that: the amount Journey switching circuit includes optical coupled switch circuit and I/V conversion i.e. current/voltage converter circuit;Range switching passes through driven by program STM32 controls the switch of optocoupler, and the resistance value that circuit and then control access circuit whether are incorporated to control parallel resistance has been come At.
3. according to claim 1 a kind of based on the adjustable digital galvanometer of STM32 range, it is characterised in that: described defeated Enter to protect circuit by carrying out overcurrent protection in two precision resistance both ends, two reversed fast switching diodes in parallel.
4. according to claim 1 a kind of based on the adjustable digital galvanometer of STM32 range, it is characterised in that: described It is digital trap that STM32 control circuit, which completes wave digital lowpass filter filtering by control program, and digital trap is by modulus The digital signal of conversion circuit output is filtered.
5. according to claim 1 a kind of based on the adjustable digital galvanometer of STM32 range, it is characterised in that: described STM32 control circuit completes digital zero setting by control button driver.
6. according to claim 1 a kind of based on the adjustable digital galvanometer of STM32 range, it is characterised in that: described STM32 control circuit is completed Digital Signal Processing by program and is calculated, and the reading of current signal is obtained.
7. according to claim 1 a kind of based on the adjustable digital galvanometer of STM32 range, it is characterised in that: the TFT Display screen shows the reading of current signal in the form of pointer and charactron are two different.
CN201811512738.0A 2018-12-11 2018-12-11 One kind being based on the adjustable digital galvanometer of STM32 range Pending CN109490614A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111521854A (en) * 2020-05-11 2020-08-11 中国地质大学(北京) Weak current measuring device

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Publication number Priority date Publication date Assignee Title
CN111521854A (en) * 2020-05-11 2020-08-11 中国地质大学(北京) Weak current measuring device

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