CN204314388U - A kind of program controlled high precision resistance measuring instrument based on analog to digital converter - Google Patents
A kind of program controlled high precision resistance measuring instrument based on analog to digital converter Download PDFInfo
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- CN204314388U CN204314388U CN201520019365.9U CN201520019365U CN204314388U CN 204314388 U CN204314388 U CN 204314388U CN 201520019365 U CN201520019365 U CN 201520019365U CN 204314388 U CN204314388 U CN 204314388U
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Abstract
The utility model discloses a kind of program controlled high precision resistance measuring instrument based on analog to digital converter, comprise high precision adjustable constant-flow source module, gear control module, instrument amplifier module, analog-to-digital converting module, processing module, display module and matrix keyboard module; Wherein, described gear control module, instrument amplifier module, analog-to-digital converting module are linked in sequence successively, gear control module, analog-to-digital converting module, display module, matrix keyboard module are connected with processing module respectively, and gear control module, high precision adjustable constant-flow source module are connected with outside testing resistance respectively.The utility model structure is simple, and easy to carry, resistance measurement relative error is less than 0.05%, and cost is low, practical.
Description
Technical field
The utility model relates to high precision instrument instrument field, particularly a kind of program controlled high precision resistance measuring instrument based on analog to digital converter.
Background technology
Precision resister surveying instrument has extremely important effect in precision resister is measured, and is one of important means of Quality of electronic products inspection.Therefore important realistic meaning is all had in the field such as maintenance and product quality inspection of new product development, electronic device.Under reality, the measurement of precision resister is easily subject to the impact of the stability of neighbourhood noise, measuring method and instrument own, and these factors must will be considered in design precision resister measuring instrument.
Current precision resister surveying instrument, mostly based on bridge measurement resistance, by resistance access electric bridge, makes no current in electric bridge flow through by the size changing variable resistor resistance.In instrument, the change of variable resistance must be even, and minimum change quantity will directly affect the precision of resistance measurement, and variable resistor resistance changes scope will directly affect the scope of resistance measurement.The object that resistance measurement scope is large in order to get to, measuring accuracy is high, this well-designed based on variable resistor needs in the resistance apparatus of bridge method, often need customized.And based on the improved Electric Bridge of bridge method, the electric bridges such as Warsaw Paderewski electric bridge, three-time balances electric bridge, Kelvin double bridge, double bridge are more complicated.Therefore very high, the bulky of this bridge method resistance measuring instrument cost, carry inconvenience and complex operation.In addition, also have the resistance apparatus of some method, method of substitution, four-wire ohm mensurations based on the comparison, but these methods all can not reach the high-acruracy survey of resistance.On market, precision can reach 0.05% pure resistance surveying instrument very rare, and often with function such as measurement electric capacity, inductance etc., price is high.
Summary of the invention
Technical problem to be solved in the utility model overcomes the deficiencies in the prior art and provides a kind of program controlled high precision resistance measuring instrument based on analog to digital converter, and resistance measurement precision of the present utility model is high, structure is simple, easy to carry, cost is low and practical.
The utility model is for solving the problems of the technologies described above by the following technical solutions:
According to a kind of program controlled high precision resistance measuring instrument based on analog to digital converter that the utility model proposes, comprise high precision adjustable constant-flow source module, gear control module, instrument amplifier module, analog-to-digital converting module, processing module, display module and matrix keyboard module; Wherein,
Described gear control module, instrument amplifier module, analog-to-digital converting module are linked in sequence successively, gear control module, analog-to-digital converting module, display module, matrix keyboard module are connected with processing module respectively, and gear control module, high precision adjustable constant-flow source module are connected with outside testing resistance respectively.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described processing module is single-chip microcomputer.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described single-chip microcomputer is MSP430F5529 single-chip microcomputer.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described high precision adjustable constant-flow source module is high precision operating amplifier OPA376 chip.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described instrument amplifier module is the high-accuracy instrument amplification chip of INA826.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described analog-to-digital converting module is ADS1118 analog/digital voltage conversion chip.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described matrix keyboard module adopts vertical 4 pin touch-switchs.
As a kind of scheme optimized further based on the program controlled high precision resistance measuring instrument of analog to digital converter described in the utility model, described display module is LCD_ILI9325 display.
The utility model adopts above technical scheme compared with prior art, has following technique effect:
(1) the utility model utilizes the high-accuracy chip of relative low price to realize the resistance measurement of 0.05% precision, and subsidiary resistance screening function; High precision operating amplifier chip OPA376, a high-accuracy instrument amplification chip INA826 and 16 analog/digital voltage conversion chip ADS1118 are the bases that program controlled high precision resistance measuring instrument reaches 0.05% measuring accuracy, employ slide rheostat between gear and carry out voltage trim, thus realize the coupling between gear;
(2) owing to adopting 16 analog/digital voltage conversion chip ADS1118, reference voltage is program control is set to 4.096V, resolution is 16 is 65535, voltage resolution △ V=4.096V/65535=62.5uV corresponding under this condition, it is 2.5mA precision current that high precision adjustable constant-flow source module can produce minimum, resistance resolution △ R=△ V/2.5mA=25m Ω.As testing resistance R=50 Ω, measuring accuracy is: 25m Ω/50 Ω=0.05%.When testing resistance is greater than 50 Europe, just can realizes measuring error and be less than 0.05%;
(3) the utility model adopts single-chip microcomputer MSP430F5529 as microcontroller center, with low noise, the high precision operating amplifier OPA376 of low quiescent current and offset voltage is as high precision tabilized current power supply core, magnifier is designed with high-accuracy instrument amplifier INA826, realize gear with the control of single-chip microcomputer to relay to control, and read testing resistance both end voltage by 16 high-precision analogs/digital quantizer ADS1118, then TFT_ILI9325 screen display shows measurement data, structure is simple, easy to carry, resistance measurement precision is high, cost is low, practical.
Accompanying drawing explanation
Fig. 1 is system principle diagram of the present utility model.
Fig. 2 is high precision adjustable constant flow source circuit figure of the present utility model.
Fig. 3 is gear control circuit figure of the present utility model.
Fig. 4 is instrument amplifier circuit figure of the present utility model.
Fig. 5 is A/D conversion circuit figure of the present utility model.
Fig. 6 is that LCD_ILI9325 screen display of the present utility model shows circuit diagram.
Fig. 7 is matrix keyboard circuit figure of the present utility model.
Fig. 8 is main control singlechip circuit diagram of the present utility model.
Embodiment
Below in conjunction with accompanying drawing, the technical solution of the utility model is described in further detail:
If Fig. 1 is system principle diagram of the present utility model, based on a program controlled high precision resistance measuring instrument for analog to digital converter, comprise high precision adjustable constant-flow source module, gear control module, instrument amplifier module, analog-to-digital converting module, processing module, display module and matrix keyboard module; Wherein,
Described gear control module, instrument amplifier module, analog-to-digital converting module are linked in sequence successively, gear control module, analog-to-digital converting module, display module, matrix keyboard module are connected with processing module respectively, and gear control module, high precision adjustable constant-flow source module are connected with outside testing resistance respectively.
Described processing module is single-chip microcomputer, and described single-chip microcomputer is MSP430F5529 single-chip microcomputer.
Described high precision adjustable constant-flow source module is high precision operating amplifier OPA376 chip.
Described instrument amplifier module is the high-accuracy instrument amplification chip of INA826.
Described analog-to-digital converting module is ADS1118 analog/digital voltage conversion chip.
Described matrix keyboard module adopts vertical 4 pin touch-switchs.
Described display module is LCD_ILI9325 display screen.
If Fig. 2 is high precision adjustable constant flow source circuit figure of the present utility model, mainly contain high precision operating amplifier OPA376 chip, C2V7 voltage stabilizing diode D1 and 1N4745 voltage stabilizing diode D2.VCC_+5V is directly connected with GND with C2V7 voltage stabilizing diode D1 by the first resistance R1, and the first resistance R1 is connected with high precision operating amplifier OPA376 chip 3 pin with C2V7 voltage stabilizing diode D1 link.OPA376 chip 4 pin is connected with VCC_-5V with VCC_+5V respectively with 7 pin, 1 pin, 5 pin and 8 pin do not connect, output pin 6 pin is connected with the second resistance R2, another termination 9013 transistor base of second resistance R2,9013 transistor collectors are as resistance access interface OUT2, and emitter is connected with OPA376 chip 2 pin and the 3rd slide rheostat R3 one end respectively, the 3rd slide rheostat R3 other end is connected with GND.Testing resistance is by the access of OUT1 and OUT2 port, and wherein OUT1 port and the 4th resistance R4 are connected with 1N4745 voltage stabilizing diode D2 link and power, the 4th another termination GND of resistance R4 another termination VCC_+18V, D2.By changing the resistance of slide rheostat R3, make the current stabilization flowing through port OUT1 and OUT2 at 2.5mA.
If Fig. 3 is gear control circuit figure of the present utility model, specifically show the circuit of gear control module, contain dpdt relay, slide rheostat, 9013 triodes and resistance.Switch 1 input end of dpdt relay K1 is connected with instrument amplifier module voltage output terminal OUT, 2 output terminals 1 of the switch 1 of K1 are connected with switch 1 input end of dpdt relay K2 and the 9th slide rheostat R9 respectively with 2, the output terminal 1 of the switch 1 of another termination GND, R9 variable resistor of the 9th slide rheostat R9 termination K1.The input end reception measuring resistance end OUT1 of the switch 2 of K1, the output terminal 1 of the switch 2 of K1 does not connect, and the output terminal 2 of the switch 2 of K1 connects the 5th resistance R5 one end, the 5th resistance R5 other end reception measuring resistance end OUT2.Dpdt relay K1 control end is connected with VCC_+5V and 9013 transistor collectors respectively, and 9013 transistor emitters meet GND, and base stage is connected with single-chip microcomputer P2.0 mouth by resistance R7.
The output terminal 1 of the switch 1 of dpdt relay K2 meets the input end OUTO_AD of analog-to-digital converting module, the output terminal 2 of the switch 1 of K2 meets the tenth slide rheostat R10, the output terminal 1 of the switch 1 of another termination GND, R10 variable resistor of the tenth slide rheostat R10 termination K2.The input end reception measuring resistance end OUT1 of the switch 2 of K2, the output terminal 1 of the switch 2 of K2 does not connect, and the output terminal 2 of the switch 2 of K2 connects the 6th resistance R6 one end, R6 other end reception measuring resistance end OUT2.Dpdt relay K2 control end is connected with VCC_+5V and 9013 transistor collectors respectively, and 9013 transistor emitters meet GND, and base stage is connected with single-chip microcomputer P2.1 mouth by resistance R8.
Control_01 and Control_02 control port is controlled by single-chip microcomputer MSP430F5529 low and high level, 00 corresponding 50 Ω-500 Ω gears, 10 corresponding 500 Ω-5k Ω gears, 01 corresponding 5k Ω-50k Ω gear (0 represents low level, and 1 represents high level).9th slide rheostat R9 and the tenth slide rheostat R10 send the voltage with A/D conversion chip ADS118 under finely tuning 500-5k Ω gear and 5k Ω-50k Ω gear, mates three gears, thus reduces measuring error.
As Fig. 4, showing the circuit of instrument amplifier module, for obtaining testing resistance OUT1 and OUT2 both end voltage, being made up of high-accuracy instrument amplification chip INA826.2 pin and 3 pin of INA826 chip do not connect, and 5 pin, 8 pin meet VCC_-18V and VCC_+18V respectively, and 6 pin meet GND, and 1 pin, 4 pin connect OUT2 and OUT1 testing resistance input end respectively.7 pin voltages export the OUT port connect in gear control module.
As Fig. 5, showing the circuit of analog-to-digital converting module, for analog voltage being converted to digital signal input single-chip microcomputer, being made up of 16 analog/digital voltage conversion chip ADS1118.3 pin, 8 pin of ADS118 chip meet GND and VCC_+5V respectively, 4 pin connect the OUTO_AD port in gear control module, 5 pin, 6 pin, 7 pin do not connect, and 1 pin, 2 pin, 9 pin, 10 pin are the programming port of ADS118, connect single-chip microcomputer P6.1, P6.0, P6.3 and P6.2 mouth respectively.
If Fig. 6 is that LCD_ILI9325 screen display of the present utility model shows circuit diagram, the 1 pin VCC that LCD_ILI9325 shields display module meets VCC_+3.3V, 2 pin GND meet GND, 3 pin LCD_CS connect MSP430F5529 single-chip microcomputer P2.4 mouth, 4 pin LCD_RD connect single-chip microcomputer P2.5 mouth, 5 pin LCD_WR connect single-chip microcomputer P2.6 mouth, 6 pin LCD_RS connect single-chip microcomputer P2.7 mouth, 7 pin LCD_DB0 connect single-chip microcomputer P3.0 mouth, 8 pin LCD_DB1 connect single-chip microcomputer P3.1 mouth, 9 pin LCD_DB2 connect single-chip microcomputer P3.2 mouth, 10 pin LCD_DB3 connect single-chip microcomputer P3.3 mouth, 11 pin LCD_DB4 connect single-chip microcomputer P3.4 mouth, 12 pin LCD_DB5 connect single-chip microcomputer P3.5 mouth, 13 pin LCD_DB6 connect single-chip microcomputer P3.6 mouth, 14 pin LCD_DB7 connect single-chip microcomputer P3.7 mouth.
If Fig. 7 is matrix keyboard circuit figure of the present utility model, matrix keyboard module is made up of 16 buttons and 4 resistance, 8 network labels KEY0, KEY1, KEY2, KEY3, KEY4, KEY5, KEY6, KEY7 draw from button one end respectively, and VCC_+3.3V is connected with KEY4, KEY5, KEY6 and KEY7 with R14 respectively by the ten one to ten four resistance R11, R12, R13.Single-chip microcomputer sweep signal outputs to KEY0, KEY1, KEY2 and KEY3 port, and judges which key is pressed by KEY4, KEY5, KEY6 and KEY7 reading low and high level.Button S1, S2, S3, S4, S5, S6, S7, S8, S9, S10 be corresponding numeral 1,2,3,4,5,6,7,8,9,0 respectively, button S11, S12 represent measuring resistance or screening resistance function, S13, S14, S15 represent 50 Ω-500 Ω, 500 Ω-5k Ω, 5k Ω-50k Ω tri-resistance gears, and S16 is for confirming button.
If Fig. 8 is main control singlechip circuit diagram of the present utility model, it is the concrete connection layout of single-chip microcomputer MSP430F5529.MSP430F5529 single-chip microcomputer P3.7, P3.6, P3.5, P3.4, P3.3, P3.2, P3.1, P3.0 meet LCD_DB7, LCD_DB6, LCD_DB5, LCD_DB4, LCD_DB3, LCD_DB2, LCD_DB1, LCD_DB0 that LCD_ILI9325 shields display module respectively, and P2.7, P2.6, P2.5, P2.4 connect LCD_ILI9325 screen display shows modular LCD _ RS, LCD_WR, LCD_RD, LCD_CS, to complete the control to display module.Matrix keyboard part, P1.7, P1.6, P1.5, P1.4, P1.3, P1.2, P1.1, P1.0 mouth of single-chip microcomputer MSP430F5529 connects matrix keyboard KEY7, KEY6, KEY5, KEY4, KEY3, KEY2, KEY1, KEY0 port respectively.P2.0 and the P2.1 mouth of single-chip microcomputer connects Control_01 and Control_02 control end respectively, and P6.0, P6.1, P6.2 and P6.3 mouth are connected AD_CS, AD_SCLK, AD_DIN and AD_DOUT respectively, as given in Fig. 3 and Fig. 5.In addition, the power supply of single-chip microcomputer MSP430F5529 does not provide.
The utility model Power supply obtains the DC voltage of+18V ,-18V ,+5V ,-5V and 3.3V again through overcommutation, filtering, fixed ampllitude after using civil power transformation, again via the filtering of 10uF and 0.1uF shunt capacitance, power respectively to MSP430F5529 single-chip microcomputer, relay, display module, matrix keyboard module, OPA376, INA826, ADS1118 chip and peripheral circuit.
Single-chip microcomputer adopts MSP430F5529 single-chip microcomputer, and this single-chip microcomputer belongs to the High Performance SCM in TI company super low power consuming single chip processor MSP430 series, is low-power consumption and high performance combination.Display module adopts LCD_ILI9325 display.
High precision adjustable constant-flow source module adopts high precision operating amplifier chip OPA376.OPA376 chip is the operation amplifier chip of a low noise, low quiescent current and offset voltage, and this chip design is ingenious, easy to use, and voltage noise, at about 10nV, can improve the overall precision of resistance measuring system.And OPA376 chip can respond small voltage, export 2.5mA precision current.When OUT1 and OUT2 holds testing resistance at 5 below k Ω, the electric current flowing through testing resistance can accurately control at 2.5mA, and the actual electric current that records is shaken at about 5uA.
Instrument amplifier module adopts high-accuracy instrument amplification chip INA826.INA826 chip has wide-range voltage and to power the feature exported with rail-to-rail voltage, and supply voltage is poor, and the absolute value of namely power positive voltage and negative electricity pressure reduction is between 2.7V-36V, and voltage exports close to chip power supply voltage.INA826 chip has the function that output voltage amplifies, and concrete, voltage gain formula is: G=49.4 k Ω/RG+1.When RG holds not connecting resistance, when namely RG is infinitely great, gain G=1.
Analog-to-digital converting module adopts 16 analog/digital voltage conversion chip ADS1118.ADS1118 chip is 16 AD conversion chip, adopts internal reference voltage, realizes reference voltage and arranges, avoid the voltage dithering caused by the external input of reference voltage, reduce the introducing of neighbourhood noise, improve the overall precision of system by programming mode.
High precision operating amplifier chip OPA376, a high-accuracy instrument amplification chip INA826 and 16 analog/digital voltage conversion chip ADS1118 are of crucial importance for the resistance measuring instrument of design 0.05% degree of accuracy.They are bases of 0.05% measuring accuracy.
Utility model works process is as follows:
User selects measuring resistance or screening resistance function by matrix keyboard.
During measuring resistance, user arranges testing resistance gear by matrix keyboard, 50 Ω-500 Ω, 500 Ω-5k Ω, 5k Ω-50k Ω third gear, and press after confirming button, single-chip microcomputer scan matrix keyboard obtains gear and arranges, and controls gear control module to respond setting.High precision adjustable constant-flow source module produces 2.5mA precision current, flow through testing resistance, after gear control module, instrument amplifier module obtains OUT1 and OUT2 port voltage value, then by analog-to-digital converting module, analog voltage is converted to digital signal and flows to single-chip microcomputer.Single-chip microcomputer reads the digital signal of voltage and calculates resistance value according to the gear of user's input, controls display module and shows resistance value in real time.
During screening resistance, user is by matrix keyboard input screening resistance, press after confirming button, Single-chip Controlling display module display screening resistance, and according to screening resistance, judge resistance belongs to which gear in 50 Ω-500 Ω, 500 Ω-5k Ω, 5k Ω-50k Ω third gear, then control gear control module and arrange to respond gear.High precision adjustable constant-flow source module produces 2.5mA precision current, flow through testing resistance, after gear control module, instrument amplifier module obtains OUT1 and OUT2 port voltage value, then by analog-to-digital converting module, analog voltage is converted to digital signal and flows to single-chip microcomputer.Single-chip microcomputer reads the digital signal of voltage and according to using affiliated gear, controlling display module and showing resistance value in real time, and when the screening resistance error that testing resistance resistance and user input is 0.05% time, display module shows and screens successfully.
The measuring resistance resistance more than shown is with ohm (Ω) for unit, and 6 bit digital displays, radix point floats, to meet the requirement of 0.05% measuring accuracy.
Obviously, above-described embodiment of the present utility model is only for the utility model example is clearly described, and is not the restriction to embodiment of the present utility model.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without the need to also giving all embodiments.And these belong to connotation of the present utility model the apparent change of extending out or variation still belong to protection domain of the present utility model.
Claims (8)
1. the program controlled high precision resistance measuring instrument based on analog to digital converter, it is characterized in that, comprise high precision adjustable constant-flow source module, gear control module, instrument amplifier module, analog-to-digital converting module, processing module, display module and matrix keyboard module; Wherein,
Described gear control module, instrument amplifier module, analog-to-digital converting module are linked in sequence successively, gear control module, analog-to-digital converting module, display module, matrix keyboard module are connected with processing module respectively, and gear control module, high precision adjustable constant-flow source module are connected with outside testing resistance respectively.
2. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter according to claim 1, it is characterized in that, described processing module is single-chip microcomputer.
3. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter according to claim 2, it is characterized in that, described single-chip microcomputer is MSP430F5529 single-chip microcomputer.
4. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter according to claim 1, is characterized in that, described high precision adjustable constant-flow source module is high precision operating amplifier OPA376 chip.
5. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter according to claim 1, is characterized in that, described instrument amplifier module is the high-accuracy instrument amplification chip of INA826.
6. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter according to claim 1, is characterized in that, described analog-to-digital converting module is ADS1118 analog/digital voltage conversion chip.
7. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter according to claim 1, is characterized in that, described matrix keyboard module adopts vertical 4 pin touch-switchs.
8. a kind of program controlled high precision resistance measuring instrument based on analog to digital converter as claimed in any of claims 1 to 7, it is characterized in that, described display module is LCD_ILI9325 display.
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| CN201520019365.9U CN204314388U (en) | 2015-01-12 | 2015-01-12 | A kind of program controlled high precision resistance measuring instrument based on analog to digital converter |
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| CN201520019365.9U CN204314388U (en) | 2015-01-12 | 2015-01-12 | A kind of program controlled high precision resistance measuring instrument based on analog to digital converter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105954590A (en) * | 2015-12-31 | 2016-09-21 | 西安航天精密机电研究所 | Insulation pathway tester |
| CN106443151A (en) * | 2016-06-30 | 2017-02-22 | 上海景格科技股份有限公司 | Line analyzer |
| CN108761342A (en) * | 2018-06-04 | 2018-11-06 | 温仕鑫 | A kind of new energy electric motor vehicle storage battery safety test method |
-
2015
- 2015-01-12 CN CN201520019365.9U patent/CN204314388U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105954590A (en) * | 2015-12-31 | 2016-09-21 | 西安航天精密机电研究所 | Insulation pathway tester |
| CN106443151A (en) * | 2016-06-30 | 2017-02-22 | 上海景格科技股份有限公司 | Line analyzer |
| CN108761342A (en) * | 2018-06-04 | 2018-11-06 | 温仕鑫 | A kind of new energy electric motor vehicle storage battery safety test method |
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Granted publication date: 20150506 Termination date: 20170112 |