CN108593723A - A kind of AD7746 capacitance acquisition systems based on timing method - Google Patents
A kind of AD7746 capacitance acquisition systems based on timing method Download PDFInfo
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- CN108593723A CN108593723A CN201810304580.1A CN201810304580A CN108593723A CN 108593723 A CN108593723 A CN 108593723A CN 201810304580 A CN201810304580 A CN 201810304580A CN 108593723 A CN108593723 A CN 108593723A
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- digital converter
- capacitance
- capacitive digital
- crossover point
- capacitor plate
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/221—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
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Abstract
The AD7746 capacitance acquisition systems based on timing method that the invention discloses a kind of, the AD7746 capacitance acquisition systems based on timing method include analog crossover point switch, capacitive digital converter and the STM32 embedded control chips being sequentially connected；It is in parallel successively between the capacitive digital converter；The AD7746 capacitances acquisition system based on timing method switchs the capacitance signal between receiving pole plate that is connected with analog crossover point by capacitor plate, analog crossover point switch connect quickly to receive the capacitance signal of measurement with capacitive digital converter, STM32 embedded control chips also connect to handle the capacitance signal received simultaneously with capacitive digital converter, and STM32 embedded control chips are connected to control the measuring sequence between capacitor plate with analog crossover point switch.
Description
Technical field
The present invention relates to capacitance signals to acquire survey calculation technical field, more particularly to the AD7746 electricity based on timing method
Hold acquisition system.
Background technology
Since electrical capacitance tomography is great potential in the two-phase flow measurement in the fields such as oil, chemical industry, metallurgy, the energy
Application value, in recent years research work related to this have obtained extensive development in the world.The base of capacitance tomography system
Present principles are to measure spatial peripheral placement capacitance sensor array (being usually made of 8 or 12 electrodes), by measuring capacitance
Capacitance between the combination of sensor Different electrodes is distributed according to the internal dielectric constant of image reconstruction algorithm acquisition and realizes that it can
Depending on change.Wherein, the accuracy of surveyed capacitance plays the role of reconstructed image quality conclusive, but by surveyed capacitance
It is worth extremely small (in pF ranks), is difficult to obtain accurate value in practical operation.Current a variety of inspections based on different principle
Survey mode has been suggested, such as direct current discharge charge electrical method, alternating current method, active differential method, the bilateral advocate approach of high-voltage alternating.Before wherein
Two methods are most common, and technology is also the most ripe.Direct current discharge charge electrical method is simple in structure, at low cost, but there are null offset, electricity
The problems such as lotus injection effect and low accuracy of detection.Alternating current method capacitive detection circuit uses sinusoidal signal excitation and phase demodulation, no
There are charge injection and null offset, accuracy of detection is high.But alternating current method circuit system is complicated, it is of high cost.It is practical to realize process
In, in the case where discrete component is more, parasitic capacitance is more, it is difficult to which designing practical high-accuracy capacitor measures electricity
Road.
Therefore, it is desirable to have a kind of AD7746 capacitances acquisition system based on timing method that can solve to occur in the prior art
Problem.
Invention content
The AD7746 capacitance acquisition systems based on timing method that the purpose of the present invention is to provide a kind of, the system body use
Chip realizes that integrated level is high, is conducive to reduce pcb board noise, interference and the precision for improving acquisition useful signal, meanwhile, it adopts
Measuring speed is improved with the method for multi-chip time-ordered measurement.
The AD7746 capacitance acquisition systems based on timing method include：The connected analog crossover point switch of sequence, capacitance
Digital quantizer and STM32 embedded control chips；The capacitive digital converter is in parallel successively between each other；It is described based on when
The AD7746 capacitances acquisition system of sequence method is connected with analog crossover point switch by capacitor plate to receive the letter of the capacitance between pole plate
Number, analog crossover point switch connect quickly to receive the capacitance signal of measurement, the embedded controls of STM32 with capacitive digital converter
Coremaking piece connect to handle simultaneously with capacitive digital converter the capacitance signal received, STM32 embedded control chips with
Analog crossover point switch is connected to control the measuring sequence between capacitor plate.
Preferably, the AD7746 capacitances acquisition system based on timing method passes through the analog crossover point switch connection
The connection of one capacitive digital converter and the capacitor plate, after the first capacitive digital converter obtains the capacitance signal measured,
The connection for disconnecting the first capacitive digital converter and the capacitor plate is switched by the analog crossover point, and connects the second electricity
Hold the connection of digital quantizer and the capacitor plate；Obtained by being measured in the processing of the first capacitive digital converter when capacitance signal,
Second capacitive digital converter starts to measure the capacitance signal of the capacitor plate；.
After the second capacitive digital converter obtains the capacitance signal measured, the is disconnected by analog crossover point switch
The connection of two capacitive digital converters and the capacitor plate, and connect third capacitive digital converter and the capacitor plate
Connection；Obtained by being measured in the processing of the second capacitive digital converter when capacitance signal, the first capacitive digital converter starts transmission electricity
Hold signal, third capacitive digital converter starts to measure the capacitance signal of the capacitor plate.
Preferably, the analog crossover point switch is connected to the capacitor plate using MT8816.
Preferably, the quantity of the capacitive digital converter is more than or equal to 3, and the capacitive digital converter uses
AD7746。
Preferably, the STM32 embedded control chips by serial ports will measure the obtained capacitance signal export to
External computer equipment.
The present invention is based on the AD7746 capacitance acquisition systems of timing method to have the advantages that：
1. circuit structure is simple, reasonable design, highly practical, various condenser type acquisition measuring circuits are can be suitably used for；
2. can be shortened using several AD7746 and measure capacitance the time it takes, strong operability；
3. circuit cost is low, use is low in energy consumption；And strong interference immunity, it is stable and reliable for performance, there is very high practical valence
Value.
Description of the drawings
Fig. 1 is the structural schematic diagram of the measuring circuit of the AD7746 capacitance acquisition systems based on timing method.
Fig. 2 is the system operation sequential comparison diagram that traditional single core piece measurement method is measured with the present invention.
Specific implementation mode
To keep the purpose, technical scheme and advantage that the present invention is implemented clearer, below in conjunction in the embodiment of the present invention
Attached drawing, technical solution in the embodiment of the present invention is further described in more detail.In the accompanying drawings, identical from beginning to end or class
As label indicate same or similar element or element with the same or similar functions.Described embodiment is the present invention
A part of the embodiment, instead of all the embodiments.The embodiments described below with reference to the accompanying drawings are exemplary, it is intended to use
It is of the invention in explaining, and be not considered as limiting the invention.Based on the embodiments of the present invention, ordinary skill people
The every other embodiment that member is obtained without creative efforts, shall fall within the protection scope of the present invention.
As shown in Figure 1, the circuit is by the analog crossover point switch MT8816, several AD7746 and the STM32 that are sequentially connected
Embedded control chip；The X0 pins of the analog crossover point switch MT8816 are connected with capacitor plate 1, X1 pins and capacitance pole
Plate 2 is connected, and X2 pins are connected with capacitor plate 3, and X3 pins are connected with capacitor plate 4, and X4 pins are connected with capacitor plate 5, X5
Pin is connected with capacitor plate 6, and X7 pins are connected with capacitor plate 8；The input terminal and analog crossover of several AD7746
Point switch MT8816 is connected, and output end is connected with the input terminal of STM32 embedded control chips；The STM32 embedded Controls
The output end of chip, several AD7746 is connected with the input terminal of STM32 embedded control chips by IIC, and STM32 is embedded
The output end of control chip is connected to computer PC by serial ports.STM32 embedded control chips are handed over by bus B US control simulations
Crunode switch MT8816.Specifically, as described below for circuit main components parameter selection：Cross point switches chip is
MT8816。
When measuring, the connection of first AD7746 and pole plate are connected by analog crossover point switch MT8816 first, the
After one AD7746 obtains the capacitance signal measured, immediately pass through analog crossover point switch MT8816 disconnect first AD7746 and
The connection of pole plate, and connect the connection of second AD7746 and pole plate.Capacitance signal obtained by being measured in first AD7746 processing
This period, second AD7746 start the capacitance signal of measuring pad.When second AD7746 obtains the capacitance letter measured
After number, immediately passes through analog crossover point switch MT8816 and disconnect the connection of second AD7746 and pole plate, and connect third
The connection of AD7746 and pole plate.This period of capacitance signal, first AD7746 obtained by being measured in second AD7746 processing
Start to transmit capacitance signal, third AD7746 starts the capacitance signal of measuring pad.And so on, this method avoid uses
When one AD7746, data are needed to wait for every time and fill the time changed with data transmission, to achieve the purpose that shorten time of measuring.
It is last it is to be noted that：The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations.To the greatest extent
Present invention has been described in detail with reference to the aforementioned embodiments for pipe, it will be understood by those of ordinary skill in the art that：It is still
Can be with technical scheme described in the above embodiments is modified, or which part technical characteristic is equally replaced
It changes；And these modifications or replacements, the essence for various embodiments of the present invention technical solution that it does not separate the essence of the corresponding technical solution
God and range.
Claims (5)
1. a kind of AD7746 capacitance acquisition systems based on timing method, which is characterized in that the capacitance acquisition system includes：Sequentially
Connected analog crossover point switch, capacitive digital converter and STM32 embedded control chips；The capacitive digital converter phase
It is in parallel successively between mutually；The AD7746 capacitances acquisition system based on timing method is switched by capacitor plate and analog crossover point
It is connected to receive the capacitance signal between pole plate, analog crossover point switch connect quickly to receive measurement with capacitive digital converter
Capacitance signal, STM32 embedded control chips connect to handle with capacitive digital converter the capacitance letter received simultaneously
Number, STM32 embedded control chips are connected to control the measuring sequence between capacitor plate with analog crossover point switch.
2. the AD7746 capacitance acquisition systems according to claim 1 based on timing method, it is characterised in that：It is described based on when
The AD7746 capacitances acquisition system of sequence method passes through the first capacitive digital converter of the analog crossover point switch connection and the electricity
Hold the connection of pole plate, after the first capacitive digital converter obtains the capacitance signal measured, is switched by the analog crossover point disconnected
The connection of the first capacitive digital converter and the capacitor plate is opened, and connects the second capacitive digital converter and the capacitance pole
The connection of plate；Obtained by being measured in the processing of the first capacitive digital converter when capacitance signal, the second capacitive digital converter starts to survey
Measure the capacitance signal of the capacitor plate；
After the second capacitive digital converter obtains the capacitance signal measured, the second electricity is disconnected by analog crossover point switch
Hold the connection of digital quantizer and the capacitor plate, and connects the company of third capacitive digital converter and the capacitor plate
It connects；Obtained by being measured in the processing of the second capacitive digital converter when capacitance signal, the first capacitive digital converter starts to transmit capacitance
Signal, third capacitive digital converter start to measure the capacitance signal of the capacitor plate.
3. the AD7746 capacitance acquisition systems according to claim 2 based on timing method, it is characterised in that：The simulation is handed over
Crunode switch is connected to the capacitor plate using MT8816.
4. the AD7746 capacitance acquisition systems according to claim 3 based on timing method, it is characterised in that：The capacitance number
The quantity of word converter is more than or equal to 3, and the capacitive digital converter uses AD7746.
5. the AD7746 capacitance acquisition systems according to claim 4 based on timing method, it is characterised in that：The STM32
Embedded control chip, which by serial ports will measure the obtained capacitance signal and export, gives external computer equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810304580.1A CN108593723A (en) | 2018-04-04 | 2018-04-04 | A kind of AD7746 capacitance acquisition systems based on timing method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810304580.1A CN108593723A (en) | 2018-04-04 | 2018-04-04 | A kind of AD7746 capacitance acquisition systems based on timing method |
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| CN108593723A true CN108593723A (en) | 2018-09-28 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111707149A (en) * | 2020-06-09 | 2020-09-25 | 西安工业大学 | Multi-channel time sequence time interval measuring device |
| CN113655289A (en) * | 2021-08-19 | 2021-11-16 | 北京他山科技有限公司 | Analog signal router for cross-chip transmission of analog signals |
| CN113777408A (en) * | 2021-08-19 | 2021-12-10 | 北京他山科技有限公司 | Distributed capacitive sensor system |
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| CN207198246U (en) * | 2017-08-23 | 2018-04-06 | 华北电力大学 | A kind of capacitance collection measuring circuit based on capacitance measurement chip |
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| CN201583315U (en) * | 2010-02-10 | 2010-09-15 | 中国电子科技集团公司第四十九研究所 | Capacitor array type liquid level sensor probe and liquid sensor using same |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111707149A (en) * | 2020-06-09 | 2020-09-25 | 西安工业大学 | Multi-channel time sequence time interval measuring device |
| CN113655289A (en) * | 2021-08-19 | 2021-11-16 | 北京他山科技有限公司 | Analog signal router for cross-chip transmission of analog signals |
| CN113777408A (en) * | 2021-08-19 | 2021-12-10 | 北京他山科技有限公司 | Distributed capacitive sensor system |
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Application publication date: 20180928 |