CN1188678C - Direct digitalized pressure transmitter and measuring method thereof - Google Patents
Direct digitalized pressure transmitter and measuring method thereof Download PDFInfo
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- CN1188678C CN1188678C CNB021587221A CN02158722A CN1188678C CN 1188678 C CN1188678 C CN 1188678C CN B021587221 A CNB021587221 A CN B021587221A CN 02158722 A CN02158722 A CN 02158722A CN 1188678 C CN1188678 C CN 1188678C
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- multivibrator
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Abstract
The present invention relates to a directly digitalized pressure transmitter which comprises a capacitance pressure sensor, a pressure measurement multivibrator circuit, an SCM, an external memory, an input device and a display unit, wherein the pressure measurement multivibrator circuit is used for receiving capacitance change values and directly converting the capacitance change values to oscillation frequency signals; the input device is used for regulating a measuring range and inputting measurement parameters. The method comprises the following steps: initializing a measuring system and carrying out operation judgment according to key values inputted by a user; if the inputted key values are used for measurement, pulse frequency is directly obtained, interpolation operation is carried out so as to obtain a pressure value, and a measuring result is displayed; if the inputted key values are used for parameter setting, the given pressure value is read in, pulse frequency measurement is carried out, and the corresponding parameter value of the pressure is calculated and stored in an external memory unit. The present invention has the advantages of intelligent functions, capability of directly transferring measurement range, visual and convenient operation, high precision, low price, convenient production and debugging, low cost and high reliability.
Description
Technical field
The present invention relates to a kind of sensor and measuring method thereof, particularly relate to a kind of sensor and measuring method thereof of Direct Digitalization.
Background technology
The FR1511 pressure unit is that one of maximum a kind of sensor is used in industrial process control.It not only can gaging pressure but also can measure flow.For capacitance pressure transmitter, continue to use the traditional mode of " sensitive measurement element---linear amplifier---analog quantity output (4-20mA) " in decades always.Though, there were some research units that it has been carried out intellectualized reconstruction both at home and abroad in nearly 2 years, develop a kind of so-called " intelligent pressure transducer ", promptly on original basis, increase the A/D conversion, i.e. " sensor---processing of---A/D conversion---microcomputer is amplified in simulation " as shown in Figure 1, but it does not still change traditional pressure unit pattern, and, even this have improved pattern slightly, still exist many shortcomings: connect very complicated analog amplify circuit and expensive A/D converter owing to used, thereby caused and utilized this pattern making pressure unit complex manufacturing, cost height; And utilize the pressure unit volume that adopts this structure to make big, be difficult for improving measuring accuracy, poor reliability.
For overcoming the shortcoming of above-mentioned prior art, the present invention proposes a kind of digitizing pressure unit that utilizes novel Direct Digital metering circuit to constitute.
Summary of the invention
The technical matters that the present invention can solve is to utilize very simple oscillatory circuit (or multivibrator), directly the variation of sensor capacitance is converted to the variation of frequency, directly digital quantity is sent into microcomputer then and is carried out pressure survey or flow measurement.
In order to achieve the above object, the invention provides a kind of digitizing pressure unit, it is characterized in that it comprises:
Capacitance pressure transducer, is used for the ambient pressure variable signal is converted to the capacitance variations value;
The pressure survey multivibrator, its input end links to each other with the electric capacity of described capacitance pressure transmitter, is used to receive described capacitance variations value, and it is converted into oscillation frequency signal;
Single-chip microcomputer is used to receive the frequency oscillator signal of being sent by described pressure survey multivibrator, and it is calculated and changes;
External memory storage is used to store the calculation result data that described single-chip microcomputer produces;
Input equipment is used to adjust range and input measurement parameter;
Display unit is used to export the demonstration that measurement result and described parameter are provided with.
The present invention also provides a kind of measuring method of Direct Digitalization, and it may further comprise the steps:
Carry out the initialization setting of measuring system, and operate according to the key assignments of user's input;
As being measurement, then
Directly obtain pulsed frequency, the row interpolation computing of going forward side by side obtains force value;
Show this measurement result;
As be parameter setting, then
Read in given force value;
Carry out pulse frequency measurement;
Calculate the relevant pressure parameter value, and be kept in the external memory unit
Direct Digital pressure unit provided by the present invention and pressure measurement method can be directly with the pressure signal digitizings, and send single-chip microcomputer to measure, and compared with prior art have following good effect:
1. have intelligent functions, need not only can carry out span shift at the scene in the laboratory verification;
2. adopt menu and function key to carry out span shift, operation is directly perceived, convenient;
3. measuring process intellectuality;
4. serial D/A conversion, the precision height, price is low;
5. realize multi-functional operation with a small amount of function key;
6. it is convenient to produce debugging;
7. cost is low;
8. reliability height.
The present invention is described in detail below in conjunction with drawings and Examples, so that purpose of the present invention, feature and good effect are had more deep understanding.
Description of drawings
Fig. 1 is the principle of work synoptic diagram of pressure unit in the prior art.
Fig. 2 is the block scheme of Direct Digital pressure unit.
Fig. 3 is a pressure survey multivibrator circuit connection layout.
Fig. 4 is a pressure survey multivibrator circuit voltage oscillation oscillogram.
Fig. 5 is a temperature compensation multivibrator circuit connection layout.
Fig. 6 is a temperature compensation multivibrator circuit voltage oscillation oscillogram.
Fig. 7 is the single-chip microcomputer main program flow chart.
Embodiment
As shown in Figure 2, the variation of ambient pressure causes the variation of the variable condenser C1 in the pressure transducer 201, and the variation of pressure causes the capacitance variations of pressure chamber, thereby change the charge and discharge time of pressure survey multi-resonant oscillating circuit 202, produce the square wave of different frequency thus; Square wave is sent into T0 counter in the single-chip microcomputer 203 (as 89C51), utilize that T1 calculates and changes the signal from the pressure survey multi-resonant oscillating circuit as timer among the 89C51; External data memory 204 is used to store data, generally, adopts I
2C bus Serial E
2PROM, but because the host CPU that the present invention uses is 89C51, this chip does not possess I
2The C bus interface, thereby with 2 I/O pin Simulation with I
2The C bus interface has reached the requirement that accurately reads and writes data in real time; Improve measuring accuracy in order to advance one one, the present invention is by using external unit (as keyboard) 205, come carrying out span shift, finish the setting and the operation of range, only need to use limited several keys in the present invention, can satisfy user's action need, see also the embodiment explanation of back about the detailed description of this part; Display unit 206 can be used to show range ability, tested pressure parameter on the one hand, on the other hand, when system works when range is provided with duty, can be used to show the duty and the range of pressure unit; When system is need be with DDZ compatible, can select by D/A converter 207, the pressure value P that calculates is converted into analog voltage signal (1-5V) by digital signal, through the voltage/current transducer voltage signal of 1-5V is converted into the normalized current signal of 4～20mA again; The D/A modular converter is to be used for some is also using simulating signal to use as the equipment interface that drives now.This module is handled later data change into 4～20mA by scale transformation and D/A change-over circuit electric current output with CPU, consider designing requirements such as " cost are low, take I/O pin and precision less as far as possible ", the present invention determines to adopt 12 bit serial D/A converter MAXIM5352.But because it is the SPI interface mode, and 89C51 does not possess the SPI interface function.We are to I
2The simulation successful experience of C bus is told us, and SPI also can simulate with the I/O pin.Behind the programming, be successful by the simulation of test of many times proof; In order further to improve measuring accuracy, system has also adopted temperature compensation multivibrator 208, it also is to adopt the Direct Digital method, the temperature compensation multivibrator is linked to each other with thermal sensing element in being arranged on capacitance pressure transducer, 201, the analog quantity of temperature variation is directly become the vibration square wave, finish the conversion of two signals (pressure and temperature) by multi-way switch 209.
As shown in Figure 3, be the circuit connection diagram of pressure survey multivibrator.This pressure survey oscillator adopts 555 timers, this is a kind of multiduty digital-to-analog hydrid integrated circuit, utilize it can be connected into Schmidt trigger, monostalbe trigger and multivibrator easily, the generation of waveform and conversion, measurement and control are owing to use flexibly, conveniently, by the digital circuit analysis as can be known, the voltage Vc on the electric capacity will be at V
T+And V
T-Between reciprocating vibration, the waveform of Vc and Vo is as shown in Figure 4.Its, computing formula was oscillation period:
T＝T
1+T
2＝(R
1+2R
2)Cln2
The oscillation frequency value can be tried to achieve by above formula, oscillation frequency can be changed by the parameter that changes R and C.The multivibrator maximum frequency of oscillation of forming with CB555 reaches 500kHz, the multivibrator maximum frequency of oscillation of forming with CB7555 can reach 1MHz, in this example, C is the parameter with change in pressure, therefore, change the numerical value of the resistance R 2 among Fig. 4, can obtain one group of pressure-frequency variation curve.As shown in Figure 5, be temperature compensation multivibrator circuit connection layout, for the temperature compensation multi-resonant oscillating circuit, the present invention adopts a kind of asymmetric multivibrator of tape input protection, when static, should make G1, G2 be operated in the break over region of voltage-transfer characteristic, bigger voltage amplification factor be arranged with assurance; Between the input end of G1 and the output terminal cross-over connection resistance R, G1 will be operated in v
O1=v
11State; Common V
TH=1/2V
DO, G2 is operated in the mid point of voltage-transfer characteristic break over region; Owing to flow through quiescent current on the R is zero substantially, so to the selection of R resistance almost without limits, be illustrated in figure 6 as the voltage waveform of each point in the circuit, computing formula oscillation period of this circuit is:
T＝T
1+T
2≈2R
FCln3＝2.2R
FC
And can must calculate oscillation frequency by this oscillation period,, can adjust the initial oscillation of oscillator, thereby obtain different sensitivity if change the value of the resistance R among Fig. 5.
The software section of native system adopts modular construction, be divided into 7 modules according to function, be respectively: automatic selection and the linearization process module and the D/A modular converter of main program module, the automatic acquisition module of pressure pulse, keyboard processing module, display module, data memory module and the range that adopts according to practical situations.
As shown in Figure 7, the main program flow chart that in single-chip microcomputer, moves for the present invention, initialization system at first, the circular wait user is by the operation of keyboard, step 701; Judge that according to the key assignments that receives current operation is to measure, or parameter setting, step 702; If measure, the then initialization horizontal pulse frequency measurement of going forward side by side, step 703; After calculating frequency, carry out interpolation calculation, try to achieve tested force value, step 704, specifically, the process of this interpolation calculation is: next interim when tested rising edge of a pulse, T0 begins counting, and T1 regularly begins simultaneously.When the T1 time then, T0 stops counting, reads the counter records time clock by micro computer then, tries to achieve the number N of the pulse of being write down in the t time, obtains pressure value P according to the scale transformation formula again; This force value is converted into the demonstration sign indicating number, and LCD shows by LCDs, step 705; If the active user operates for parameter setting by the keyboard input, then read in given force value, step 706 earlier; Carry out the measurement of pulsed frequency then, step 707; Calculate the relevant pressure parameter value at last, and be stored in external memory storage E
2Among the PROM, step 708.
Owing to consider that the instrument space is unsuitable excessive, three function key K1, K2 and K3 only are set, adopt the interrupt mode interface, the setting of operation keyboard illustrates as follows:
Because number of keys is limited, and in order to satisfy the needs of adjusting function, each key is set to double function key, is used to set the range grade and carries out span shift, and its concrete function is as follows:
Add 1 key K1
Enter grade when the key of pressing first is this key the interface is set, whenever click later on, the level cells of range grade picture adds 1, and shows the pairing range of this grade below.When the range grade is added to maximal value, press the K1 key again, the range grade will be got back to minimum value, promptly realize the Automatic Cycle selection;
When in the span shift interface, pressing this key, then add 1 key as span shift, promptly, add 1 in upper limit unit whenever by a K1, Dui Ying lower limit also adds 1 with it, and according to the Automatic Cycle function is arranged;
Subtract 1 key K2
When the key of pressing first is this key, enter grade the interface is set, whenever click later on, the range grade subtracts 1, and shows the range of this grade representative below.When the range grade is reduced to minimum value, press the K1 key again, the range grade will be got back to maximal value, promptly realize the Automatic Cycle selection;
When in the span shift picture, pressing this key, then subtract 1 key as span shift, promptly, subtract 1 in upper limit unit whenever by a K1, Dui Ying lower limit also subtracts 1 with it;
Acknowledgement key K3
When pressing K3 for the first time, enter range and adjust the interface, parameter is carried out the initialization setting.
When K3 is not when pressing for the first time, then be the interface acknowledgement key, the switching between the realization interface.
The above; it only is better embodiment of the present invention; should not be considered to be limitation of the scope of the invention; and the claim scope that the present invention advocated is not limited thereto; all personages who is familiar with this field skill; according to the disclosed technology contents of the present invention, can think easily and equivalence change, all should fall into protection scope of the present invention.
Claims (9)
1. the pressure unit of a Direct Digitalization is characterized in that it comprises:
Capacitance pressure transducer, is used for the ambient pressure variable signal is converted to the capacitance variations value;
The CB555 multivibrator, its input end links to each other with the electric capacity of described capacitance pressure transmitter, is used to receive described capacitance variations value, and it is converted into oscillation frequency signal;
Single-chip microcomputer is used to receive the frequency oscillator signal that described CB555 multivibrator is sent, and it is calculated and changes;
External memory storage is used to store the calculation result data that described single-chip microcomputer produces;
Input equipment is used to adjust range and input measurement parameter;
Display unit is used to export the demonstration that measurement result and described parameter are provided with.
2. the pressure unit of Direct Digitalization as claimed in claim 1 also comprises the temperature compensation multivibrator, is used to receive the oscillator signal that temperature variation produces.
3. the pressure unit of Direct Digitalization as claimed in claim 2 also comprises multi-way switch, is used for the output signal of pressure survey multivibrator and temperature compensation multivibrator is carried out time sharing sampling.
4. the pressure unit of Direct Digitalization as claimed in claim 1, wherein said external input device are keyboard, and its key assignments is respectively and adds 1 key, subtracts 1 key and acknowledgement key.
5. the pressure unit of Direct Digitalization as claimed in claim 1 also comprises 12 serial D/A converter, and the pressure value P that is used for calculating is converted into analog voltage signal by digital signal, with other pressure unit compatibilities.
6. pressure measurement method that adopts the pressure unit of Direct Digitalization may further comprise the steps:
Single-chip microcomputer receives the frequency oscillator signal that the CB555 multivibrator is sent;
Carry out the initialization setting of measuring system, and carry out operation judges according to the key assignments of user's input;
As being measurement, then
Directly obtain pulsed frequency, the row interpolation computing of going forward side by side obtains force value;
Show this measurement result;
As be parameter setting, then
Read in given force value;
Carry out pulse frequency measurement;
Calculate the relevant pressure parameter value, and be kept in the external memory unit.
7. the pressure measurement method of the pressure unit of employing Direct Digitalization as claimed in claim 6 is used for pressure and flow measurement.
8. the pressure measurement method of the pressure unit of employing Direct Digitalization as claimed in claim 6 comprises main program module, the automatic acquisition module of pressure pulse, keyboard processing module, display module and data memory module.
9. the pressure measurement method of the pressure unit of employing Direct Digitalization as claimed in claim 8 also comprises automatic selection and the linearization process module and the D/A modular converter of range.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021587221A CN1188678C (en) | 2002-12-26 | 2002-12-26 | Direct digitalized pressure transmitter and measuring method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021587221A CN1188678C (en) | 2002-12-26 | 2002-12-26 | Direct digitalized pressure transmitter and measuring method thereof |
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|---|---|
| CN1419114A CN1419114A (en) | 2003-05-21 |
| CN1188678C true CN1188678C (en) | 2005-02-09 |
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Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1325890C (en) * | 2005-06-14 | 2007-07-11 | 浙江中控技术有限公司 | Circuit of testing capacitance and capacitance type pressure transmitter |
| CN100498865C (en) * | 2006-10-20 | 2009-06-10 | 沈阳中科博微自动化技术有限公司 | Pressure digital acquisition front end |
| CN102032974B (en) * | 2010-11-15 | 2012-06-27 | 浙江工商大学 | Temperature compensation method for pressure sensor |
| CN102183897B (en) * | 2011-01-06 | 2012-10-17 | 上海理工大学 | SOC (System on Chip)-based pulse interpolation circuit |
| CN102681678B (en) * | 2011-03-08 | 2016-03-23 | 汉王科技股份有限公司 | There is time writer and its implementation of pressure sensitivity erase feature |
| CN102681677B (en) * | 2011-03-08 | 2015-12-09 | 汉王科技股份有限公司 | For time writer and the pressure sensitivity control method thereof of electronic whiteboard |
| CN104238379B (en) * | 2013-06-07 | 2017-07-28 | 艾默生过程控制流量技术有限公司 | Transmitter, field instrument and the method for controlling transmitter |
| CN103674352B (en) * | 2013-12-18 | 2019-02-12 | 重庆德尔森传感器技术有限公司 | Pressure transmitter signal processing chip and capacitance differential pressure pressure transmitter |
| CN105571764A (en) * | 2016-03-10 | 2016-05-11 | 北京纳衡仪器仪表有限公司 | Remote-transmission digital pressure measuring device |
| CN106853281B (en) * | 2016-11-25 | 2017-11-14 | 南阳师范学院 | Carbon dioxide colloidal foam extinguishing chemical and its compound method |
| CN112267549A (en) * | 2020-10-10 | 2021-01-26 | 浙江飞创环境科技有限公司 | Integrated pump station |
| WO2022198728A1 (en) * | 2021-03-23 | 2022-09-29 | 微传智能科技（上海）有限公司 | Female pelvic floor muscle pressure measurement method and system |
| CN116296047B (en) * | 2023-04-03 | 2023-09-29 | 淮阴工学院 | Temperature compensation improvement method of monocrystalline silicon pressure transmitter |
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2002
- 2002-12-26 CN CNB021587221A patent/CN1188678C/en not_active Expired - Fee Related
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| CN1419114A (en) | 2003-05-21 |
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