CN102313622A - Capacitance detection circuit and capacitive type pressure transmitter - Google Patents

Capacitance detection circuit and capacitive type pressure transmitter Download PDF

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CN102313622A
CN102313622A CN 201110130290 CN201110130290A CN102313622A CN 102313622 A CN102313622 A CN 102313622A CN 201110130290 CN201110130290 CN 201110130290 CN 201110130290 A CN201110130290 A CN 201110130290A CN 102313622 A CN102313622 A CN 102313622A
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capacitance
connected
circuit
frequency
resistor
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CN 201110130290
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Chinese (zh)
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万军
刘仁广
王天成
王洪元
陈云
龙霄
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常州大学
江苏红光仪表厂有限公司
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Abstract

The invention discloses a capacitance detection circuit and a capacitive type pressure transmitter, the capacitance detection circuit is a field-mounted pressure signal acquisition unit in an industrial instrument and comprises a capacitive type pressure sensor, a multi-way switch and a capacitance-frequency conversion circuit, and the capacitive type pressure sensor is used for converting external pressure change signals to capacitance change values; the multi-way switch is used for switching capacitance on the two sides; and the capacitance-frequency conversion circuit is a self-excited oscillation circuit and is used for converting capacitance signals on the driven side, which are outputted by the multi-way switch, to frequency signals. The multi-way switch is adopted, a same square wave self-excited oscillator is used for performing time division sampling, the charge and discharge characteristics of the capacitance are fully utilized, changes of the capacitance are reflected on the changes of oscillation frequency of the circuit, an oscillation circuit does not need to be additionally designed, an alternating current power supply is not required and only a direct current power supply is required, thereby simplifying a measuring circuit and avoiding introduction of alternating current interference.

Description

电容检测电路及电容式压力变送器 The capacitance detection circuit and the capacitive pressure transmitter

技术领域 FIELD

[0001] 本发明涉及检测电路及变送器,具体涉及一种基于WIA无线网络的电容检测电路及电容式压力变送器。 [0001] The present invention relates to a transmitter and a detection circuit, particularly relates to a capacitance detecting circuit based on the wireless network and WIA capacitive pressure transmitter.

背景技术 Background technique

[0002] 电容式压力变送器在工业过程控制中有着广泛的应用。 [0002] The capacitive pressure transducer has been widely used in industrial process control. 对于电容式压力变送器, 其前端电路即为电容检测电路。 For capacitive pressure transmitter, which is the front-end circuit capacitance detection circuit. 电容检测的基本电路有两类:其一是把电容作为一个阻抗元件,按照电阻-电压转换的方式进行变换,但其中电源必须采用交流电源;其二是充分利用电容的充放电特性进行变换。 The basic capacitance detection circuit there are two types: one is the capacitance as an impedance element, according to the resistance - is converted voltage conversion mode, but must be AC ​​power; second, full use of the capacitance charging and discharging characteristics are transformed.

[0003] 目前,在电容式压力变送器中大多采用电容-电压转换的方法来设置电容检测电路,因此需要设计振荡电路以提供交流电源,然而,该频率一般为几千赫兹,并且,频率过高会使寄生电容的影响过大,过低则不利于计较个容抗闸的差别,因此,采用电容-电压转换原理设计的电容检测电路具有电路复杂,庞大的特点,对电容式压力变送器的小型化十分不利,同事也给电路的温漂补偿,非线性补偿带来了很大的不便。 [0003] Currently, the capacitive pressure transmitter mostly capacitive - voltage converting method to set the capacitance detection circuit, the oscillation circuit needs to be designed to provide AC power, however, the frequency is typically a few kilohertz, and the frequency causes excessive influence of parasitic capacitance is too large, is not conducive to low notwithstanding the differences in a gate capacitance, and therefore, use of a capacitance - voltage converting circuit of the capacitance detection principle design of a circuit complex, bulky characteristics of the variable capacitive pressure miniaturized transmitter is very bad, my colleagues also brought a lot of inconvenience to the temperature drift compensation, non-linear compensation circuit.

[0004] 在公告号为CN 1188678C的中国专利中公开了一种直接数字化的压力变送器及其测量方法,它采用电容式压力传感器和CB555多谐震荡器完成:将外界压力变化信号转换为电容变化值,并将电容变化值转换为震荡频率信号,以便后续的单片机进行计算和转换。 [0004] disclosed in Chinese Patent Publication No. CN 1188678C in a pressure transmitter and a direct digital measurement method, which uses a capacitive pressure sensor and CB555 multivibrator complete: the external pressure change signal is converted to capacitance change value and the capacitance value is converted into a change oscillation frequency signal for subsequent calculation and conversion of the microcontroller. 该专利利用了电容充放电特性惊醒电容测量,但是,由于采用两个CB555多谐振荡器分别对两边电容进行采样,因此造成结构上复杂的后果,从而提高成本,另外,两个CB555多谐振荡器存在合体差异,由此影响了测量精度。 This patent utilizes the capacitor charge and discharge characteristics awakened capacitance measurement, however, since the multivibrator CB555 two sides respectively sampling capacitor, thus resulting in a complicated structure effects, thereby increasing the cost. In addition, two multivibrator CB555 differences exist body, thereby affecting the measurement accuracy.

[0005] 上世纪70〜80年代开始,工业无线技术还是一种单纯的通信手段,作为有线技术的补充以解决长距离的数据传输为目的,可实现点对点、点对多点通信。 [0005] - the 1970s 1980s, industrial wireless technologies is also a simple means of communication, as a supplement to wired technologies to address data for the purpose of long-distance transmission can be realized point-to-multipoint communication. 本世纪初,为了实现泛在感知,推动工业测控模式变革,解决低成本的信息获取,工业无线技术开始实现大规模网络化。 The beginning of this century, in order to achieve ubiquitous perception, promotion of industrial measurement and control mode changes to address information access to low-cost, large-scale industrial wireless networking technology began.

发明内容 SUMMARY

[0006] 本发明的目的在于:提供一种电容检测电路及电容式压力变送器,避免采用两个CB555多谐振荡器来进行前端电容测量,造成成本低,测量精度高。 Objective [0006] The present invention is: to provide a capacitance detection circuit and a capacitive pressure transmitter, to avoid using two CB555 multivibrator capacitance measurements to the distal end, resulting in low cost and high precision.

[0007] 本发明的技术解决方案是:电容检测电路是工业仪表中现场安装的压力信号采集单元,它包括电容式压力传感器、多路开关和电容频率转换电路;其中,电容式压力传感器: 用于将外界压力变化信号转换为电容变化值;多路开关:其输入端连接电容式压力传感器,其输出端连接电容频率转换电路,用于对电容式压力传感器的两测电容进行切换;电容频率转换电路:为一自激振荡电路,用于对多路开关输出的被侧电容信号转换成频率信号, 电容频率转换电路通过被测电容与滞回比较器以及锁存器相连来构成自激振荡电路,所述振荡频率的大小体现被测电容的大小,后继电路对该频率值进行采样即获得其频率值。 [0007] The technical solutions of the present invention are: the capacitance detection circuit is a pressure signal acquisition unit industrial instrumentation field installation, comprising a capacitive pressure sensor, multiple switches and capacitors frequency converting circuit; wherein the capacitive pressure sensor: with the pressure change in the external signal is converted to a capacitance change values; multiplexer:; frequency capacitor having an input connected capacitive pressure sensor having an output capacitor connected to the frequency conversion circuit for the two test capacitance of the capacitive pressure sensor switch converting circuit: is a self-oscillating circuit for multiplexer output-side capacitance is converted into a signal of a frequency signal, a frequency converting circuit capacitance measured by the capacitance hysteresis comparator and a latch connected to constitute a self-oscillation circuit, the oscillation frequency reflects the size of the measured magnitude of the capacitance, the circuit samples the subsequent frequency value a frequency value that is obtained.

[0008] 本发明还可以通过运放来构建自激振荡电路,所述被测电容的变化转换成频率变化输出。 [0008] The present invention can also be constructed by op amp self-oscillation circuit, the measured capacitance variation is converted into the output frequency change.

[0009] 其中,所述电容频率转换电路包括运放、积分电阻R、分压电阻R1、电阻R2、电阻R3,运放的输出电压经RC电路积分后送入运放的反响输入端,其反相输入端连接被测电容,运放输出电压经反馈电阻R3进入同相端,电源VCC作为参考电压经Rl加到运放同相输入端。 [0009] wherein the capacitance frequency conversion circuit comprises operational amplifiers, integrating resistor R, voltage-dividing resistor R1, a resistor R2, a resistor R3, the output voltage of the op amp integrator RC circuit is fed via the input terminal of the operational amplifier response, which measured capacitance connected to the inverting input terminal, the output voltage of operational amplifier via a feedback resistor R3 noninverting terminal, a reference voltage supply VCC through Rl applied to the noninverting input of the op amp.

[0010] 其中,所述运放输入的周期T=2RCln ((R3+R2) /R3),振荡频率f为1/T,在R2、R3、R 的阻值确定时,频率由电容C决定。 [0010] wherein the op amp input period T = 2RCln ((R3 + R2) / R3), f is the oscillation frequency 1 / T, in R2, R3, when the resistance R is determined, the frequency determined by the capacitance C .

[0011] 其中,所述电阻为精密电阻。 [0011] wherein said resistor is a precision resistor.

[0012] 本发明提供一种电容式压力变送器,它包括电容检测电路、单片机、存储器、输入设备和显示单元,电容检测电路包括:包括电容式压力传感器、多路开关和电容频率转换电路,电容式压力传感器:用于将外界压力变化信号转换为电容变化值;多路开关:其输入端连接电容式压力传感器,其输出端连接电容频率转换电路,用于对两侧电容进行切换;电容频率转换电路:其为一自激振荡电路,用于对多路开关输出的北侧电容信号转换成频率信号;单片机:用于对多路开关的控制以及接收电容频率转换电路送出的频率信号,并对其进行计算和转换;存储器:用于存储单片机产生的计算结果数据;输入设备:用于调整量程和输入测量参数;显示单元:勇于输出测量结果及所述参数设置的显示。 [0012] The present invention provides a capacitive pressure transmitter, which includes a capacitance detecting circuit, a microcontroller, a memory, an input device and a display unit, a capacitance detecting circuit comprising: a capacitive pressure sensor, and a multi-way switch capacitance frequency conversion circuit , capacitive pressure sensor: for external pressure change signal is converted to a capacitance change values; multiplexer: an input terminal connected to the capacitive pressure sensor having an output capacitor connected to the frequency converting circuit, for both sides of the capacitor switching; frequency conversion circuit capacitor: it is a self-oscillation circuit, for conversion into a frequency signal of capacitor north multiplexer output signal; microcontrollers: a circuit for converting the frequency of the signal sent to the control capacitor and receiving frequency multiplex switch , and subjected to calculation and conversion; memory: means for storing the calculation result data generated by the microcontroller; input device: an input for adjusting the range and measurement parameters; the display unit: displays a measurement result, and courage of the output parameter set.

[0013] 其中,所述被测电容与滞回比较器相连构成自激振荡器电路,所述振荡频率的大小体现被测电容的大小。 [0013] wherein, said measured capacitance and hysteresis comparator connected to constitute a self-excited oscillator circuit, the oscillation frequency reflects the size of the size of the measured capacitance.

[0014] 其中,所述电容频率转换电路包括运放、积分电阻R、分压电阻R1、电阻R2、电阻R3、运放的输出电压经RC电路积分后送入运放的反相输出端,其反相输出端连接被测电容,运放输出电压经反馈电阻R3进入同相端,电源VCC作为参考电压经Rl加到运放同相输入端。 [0014] wherein the capacitance frequency conversion circuit comprises operational amplifiers, integrating resistor R, voltage-dividing resistor R1, a resistor R2, a resistor R3, the output voltage of the op amp integrator RC circuit is fed via the inverting output terminal of the operational amplifier, the inverting output terminal connected to capacitance, the output voltage of the operational amplifier via a feedback resistor R3 noninverting terminal, a reference voltage supply VCC through Rl applied to the noninverting input of the op amp.

[0015] 本发明具有以下优点: [0015] The present invention has the following advantages:

1、本发明采用多路开关,用同一个方波自激振荡器进行分时采样,充分利用了电容的充放电特性,将电容的变化体现在电路振荡频率的变化上,无需另外设计振荡电路,无需交流电源,只需直流电源,从而简化了测量电路,也避免了交流干扰的引入。 1, the present invention employs a multiplexer, a time division sampled square wave with the same self-excited oscillator, full use of the capacitor charge and discharge characteristics, the change in capacitance is reflected in the change in the oscillation frequency of the circuit, no additional oscillation circuit design , no AC power, only the DC power supply, thus simplifying the measuring circuit, but also to avoid the interference introduced into the exchange.

[0016] 2、本发明提高了比较器部分运放的速度,减小了积分环节中电阻的大小,进一步提高测量电路的测量精度,该电路的原理也决定了比较容易实现非线性及温漂等的补偿。 [0016] 2, the present invention improves the operational amplifier comparator section the speed is reduced in magnitude of the resistance of the integrator, to further improve the measurement accuracy of the circuit, the principle of the circuit is relatively easy to implement also determines the linear drift and and other compensation.

[0017] 3、变送器基于智能无线网络WIA技术,符合IEEE 802. 15. 4无线通信标准,主要面向设备间信息的无线通信,使用符合中国无委会规定的自由频带,解决恶劣环境下遍布的各种大型器械、金属管道等对无线信号的反射、散射造成的多径效应,以及马达、器械运转时产生电磁噪声对无线通信的干扰,提供能够满足应用需求的高可靠、实时无线通信服务,具有很强的抗干扰能力、超低功耗、实时通信等技术特征。 [0017] 3, the transmitter-based intelligent wireless network WIA technology, IEEE 802. 15. 4 line with a wireless communication standard, the main information for inter-device wireless communication in a predetermined frequency band compatible with the freedom to use non-China Committee, under harsh environments solution reflecting the radio signal throughout a large variety of devices, metal pipes, etc., multipath effects due to scattering and interference of electromagnetic noise is generated when the motor is radio communication, the device operation, to meet the application needs to provide high reliability, real-time wireless communication service, with strong technical features anti-jamming capability, low power consumption, real-time communications.

[0018] 4、所述振荡频率的大小体现被测电容的大小,本发明正是由于电容的大小决定了充放电的时间的大小,继而决定了比较器输出波形的频率大小,由此电容检测电路输出波形的频率体现了被测电容的大小,后继电路只需对该频率值进行采样即可获得其频率值。 [0018] 4, the oscillation frequency reflects the size of the magnitude of the capacitance measured, the present invention is precisely because the capacitor size determines the size of the charge and discharge time, which in turn determines the magnitude of frequency of the output of the comparator, whereby the capacitance detection waveform reflects the output frequency of the circuit size of the measured capacitance, the circuit simply sampling the subsequent frequency value a frequency value that can be obtained.

[0019] 5、本发明的压力变送器的前端检测电路通过多路开关切换,在利用自激振荡器对两侧电容的分时采样,得到频率值,由于保证两侧的转换使用相同的振荡电路,进而简化了电路,从而避免了因采用两个CB555组成的压力测量多谐振荡电路的个体差异而影响测量精度的问题。 [0019] 5, the pressure transmitter of the present invention through the front end detection circuit multiplexer switch, the self-excited oscillator using time division sampling capacitor both sides to obtain a frequency value, since both sides to ensure the conversion of the same the oscillation circuit, thereby simplifying the circuit, thus avoiding problems due to the use of the composition of two pressure measuring individual differences CB555 multivibrator circuit and affect the measurement accuracy. 附图说明 BRIEF DESCRIPTION

[0020] 图1是本发明电容式压力变送器的结构示意图。 [0020] FIG. 1 is a schematic view of a capacitive pressure transmitter of the present invention.

[0021] 图2是图1的电容检测电路原理图。 [0021] FIG. 2 is a schematic diagram of the capacitance detection circuit of FIG. 1.

[0022] 图3是图1的数据采集及温度补偿电路图。 [0022] FIG. 3 is a circuit diagram of the temperature compensation data acquisition and FIG.

[0023] 图4是图1的数据处理电路及无线接口。 [0023] FIG. 4 is a data processing circuit of Figure 1, and a wireless interface.

[0024] 图中:1、天线,2、液晶显示器,3、管道,4、外壳,5、电容传感器探头。 [0024] FIG: 1, an antenna 2, a liquid crystal display, 3, pipe, 4, the housing 5, the capacitance sensor probe. 具体实施方式 detailed description

[0025] 下面结合附图和实施例进一步说明本发明的技术解决方案,实施例不应理解为对技术解决方案的限制。 [0025] The following examples further illustrate and technical solutions of the present invention in conjunction with the accompanying drawings, embodiments should not be construed as limiting the technical solutions.

[0026] 电容检测电路可应用于很多电容式压力变送器,以下就几个电容式压力变送器为例来说明采用上述电容检测电路的电容式压力变送器,请参阅图1-4,其为本发明的一种电容式压力变送器的结构和电路原理图,它包括电容检测电路、单片机、存储器、输入设备和显示单元,电容检测电路包括电容式压力传感器、多路开关及电容频率转换电路,其中,电容式压力传感器包括高压侧测压电容和低压侧测压电容,利用多路开关进行切换以及利用电容频率转换电路实现分时采样,并将采样值C经过转换成频率信号,其中,电容式压力传感器:用于将外界压力变化信号转换为电容变化值;多路开关:其第一输入端连接单片机P3. 3 口,控制高压侧测压电容与反馈电阻Rl —端的通断;第二输入端连接单片机P3.0 口, 控制低压侧测压电容与反馈电阻Rl—端的通断; [0026] The capacitance detecting circuit can be applied to many capacitive pressure transmitter, the pressure transmitter on several capacitive example to illustrate the capacitive pressure transmitter with the capacitance detection circuit, see Figure 1-4 , which is a capacitive pressure transducer structure of the present invention and a circuit diagram, which includes a capacitance detecting circuit, a microcontroller, a memory, an input device and a display unit, a capacitance detection circuit comprises a capacitive pressure sensor, and multiplexer capacitance frequency conversion circuit, wherein the capacitive pressure sensor comprising a high pressure side and a low side load capacitance load capacitance, multi-button switches and the use of capacitance-frequency conversion circuit to achieve time-sampled and sample values ​​into a frequency through C signal, wherein the capacitive pressure sensor: for external pressure change signal is converted to a capacitance change values; multi-way switch: a first input terminal connected to the microcontroller P3 3 port to control the high pressure side load capacitance of the feedback resistor Rl - end. off; a second input connected microcontroller port P3.0, control the low side load capacitance of the feedback resistor Rl--off end; 第三输入端连接单片机P3. 1 口,控制精密电容Cl与反馈电阻Rl —端的通断;第四输入端连接单片机P3. 2 口,控制插座)(Z5的一端与反馈电阻Rl —端的通断;电容频率转换电路:采用运放和锁存器来构建自激振荡电路, 它包括运放1、运放2、分压电阻R2、电阻R3、电阻R4、反馈电阻R1、与非门1、与非门2、滤波电容C14、电容C15、计数器1和计数器2,VCC经Rl加到运放1的同相输入端,再经R3加到运放2的反相输入端,最后经R4到地;运放1的同相输入端和运放2的反相输入端分别接滤波电容C14,电容C15到地;运放1的输出端同与非门2的一个输入端相连,与非门2的另一输入端同与非门1的输出端相连,与非门2的输出端同与非门1的一个输入端相连,与非门1的另一个输入端与运放2的输出端相连,运放1的输出还与计数器1的时钟驱动输入端,反馈电阻Rl的一端相连;反馈电阻 A third input connected to the microcontroller P3 1 port precisely controlled capacitors Cl feedback resistor Rl - end off;.. A fourth input terminal connected to the microcontroller P3 2 port control socket) end (Z5 of the feedback resistor Rl - end-off ; capacitance frequency conversion circuit: using the operational amplifier and a latch constructed self-oscillating circuit comprising an operational amplifier, op amp 2, voltage dividing resistor R2, a resistor R3, a resistor R4, a feedback resistor R1, a NAND gate, NAND gate 2, the filter capacitor C14, capacitor C15, the counter 1 and counter 2, the VCC applied to the op amp by Rl noninverting input terminal 1, and then added by R3 operational amplifier inverting input terminal 2, and finally to ground through R4 ; op amp with a phase input and an operational amplifier inverting input terminal 2 are respectively connected filter capacitor C14, capacitor C15 to ground; amplifier output terminal 1 is connected with one input terminal of the NAND gate 2, the NAND gate 2 the other input terminal with the output terminal of the NAND gate 1 is connected to the output terminal of the NAND gate is connected to the same with a 2 input NAND gate 1, and the other input terminal of the NAND gate 1 and the output 2 of the operational amplifier is connected, the output of operational amplifier 1 and further driving a clock input terminal of a counter, coupled to one end of a feedback resistor Rl; feedback resistor 的另一端与多路开关的四个输入端、运放1的反相输入端及运放2的同相输入端相连;计数器1的第四位输出端与计数器2的时钟驱动输入端相连,计数器2的第二位和第三位输出端与单片机的Pl. 2 口、Pl. 3 口相连;电源:3. 3V锂电池供电,主控制器电路板中使用3. 3V转3V可控开关芯片对模拟部分和数字部分提供所需的电源;3. 3V 电源由〇3、(:14、(:15、(:16、020、021、022、(^4滤波,3¥ 电源由C1、C9、C10、 C18滤波;单片机:选用美国德州电气公司的MSP430F149芯片;晶振选用3. 6264MHz,程序下载使用标准JTAG接口;XT2IN、XT20UT与晶振连接,之间连接电阻R17,经过Cll、C12到地;MCU的54、55、56、57脚分别与双排座JP2的1、3、5、7脚相连,MCU的12和22脚分别与JP2的2脚和6脚相连,MCU的58脚与JP2的11脚相连;EEPROM存储器:片外存储芯片选用Microchip公司的MLC64芯片,采用I2C接 The other end of the four input multiplexer switch, the inverting input of an operational amplifier and the noninverting input of the operational amplifier 2 is connected; connected to the fourth clock output of the counter 1 and the counter driving an input terminal 2, the counter . Pl second and third output of the microcontroller 2 of 2, Pl. 3 I connected; power:. 3 3V lithium battery, the main controller circuit board using transfected 3. 3V 3V controllable switch chip to provide the desired power to the analog and digital portions; 3 3V powered by 〇3, (: 14, (: 15, (: 16,020,021,022, (^ 4 filter, a power supply. 3 ¥ C1, C9 , C10, C18 filtering; microcontroller: selection electric company Texas MSP430F149 chip; crystal selection 3. 6264MHz, using the standard JTAG interface program download; XT2IN, XT20UT the crystal is connected, is connected between the resistor R17, through Cll, C12 to ground; 54,55,56,57, respectively the MCU pin 1,3,5,7 foot double seat JP2 connected, the MCU 12 and the pin 22 connected to pin 2 of JP2 and 6 feet, respectively, the MCU 58 feet and JP2 pin 11 is connected; the EEPROM memory: off-chip memory chip used Microchip's MLC64 chip, using the I2C 口;由3. 3V电源供电,5、6号管脚通过R20、R21上拉电阻与MCU的P4. 5、P4. 6 口相连,C25用于滤波,1、2、3、4号脚接地用于指示物理地址;显示器:选用SPI总线结构的48管脚HT1621B驱动液晶屏幕,其中SEGO〜SEG23和COMO〜COM3共M个管脚与液晶玻璃连接,DATA管脚接上拉电阻R52的一端再与MCU的P5. 1 口连接,CS管脚接上拉电阻R53的一端再与MCU的Pl. 5 口连接,WR管脚接上拉电阻R54的一端再与MCU的Pl. 6 口连接,RD管脚接上拉电阻R55的一端再与MCU的Pl. 7 口连接,上拉电阻R52、R53、R54、R55的另一端与VDD连接,VDD与VLCD管脚之间连接R51可变电阻,VDD与VSS分别于主控制器电路板上的3. 3V电源和地线连接,其余管脚悬空;无线通信:MCU的P3. 4、P3. 5 口与WIAPA-M1800无线通信模块的串口接口相连。 Mouth; a 3. 3V supply, 5,6 pins through R20, and the pull-up resistor on the MCU P4 5 R21, is connected to port P4 6, C25 for filtering, 1,2,3,4 feet grounded. is used to indicate the physical address; display: selection pin HT1621B SPI bus structure 48 driving a liquid crystal screen, and wherein SEGO~SEG23 COMO~COM3 M pins were connected to the LCD glass, DATA pin is connected to one end of the pull-up resistor R52 and then . 1 connected to P5 of the MCU, CS pin is connected to one end of the pull-up resistor R53 and the MCU then Pl. 5 is connected, WR pin pull-up resistor R54, one end of Pl and then the MCU. 6 is connected, RD pull-up resistor R55 connected to one end of the pin of the MCU and then Pl. 7 is connected to the pull-up resistors R52, R53, R54, R55 and the other end connected to VDD, a variable resistor R51 connected between pin VDD and VLCD, VDD 3. 3V power and ground to the main controller circuit board is connected to the VSS, respectively, the remaining pin is floating; wireless communication:.. MCU of P3 4, P3 5 port to the serial port WIAPA-M1800 wireless communication module.

Claims (10)

  1. 1.电容检测电路,其特征在于:它包括电容式压力传感器、多路开关和电容频率转换电路,电容式压力传感器:用于将外界压力变化信号转换为电容变化值;多路开关:其输入端连接电容式压力传感器,其输出端连接电容频率转换电路,用于对两侧电容进行切换;电容频率转换电路:为一自激振荡电路,用于对多路开关输出的被侧电容信号转换成频率信号。 1. The capacitance detection circuit, characterized in that: it comprises a capacitive pressure sensor, a capacitance and the switching frequency multiplex conversion circuit, the capacitive pressure sensor: for external pressure change signal is converted to a capacitance variation value; multiplexer: input end of the capacitive pressure sensor is connected, an output terminal connected to capacitance frequency conversion circuit, for switching both capacitors; capacitance frequency conversion circuit: is a self-oscillating circuit for multiplexer output side capacitor signal conversion is into a frequency signal.
  2. 2.如权利要求1所述的电容检测电路,其特征在于:所述被测电容与滞回比较器相连, 以构成自激振荡电路,所述振荡频率的大小体现被测电容的大小。 2. The capacitance detecting circuit according to claim 1, wherein: said measured capacitance coupled comparator with hysteresis, to constitute a self-oscillation circuit, the oscillation frequency reflects the size of the size of the measured capacitance.
  3. 3.如权利要求1所述的电容检测电路,其特征在于:自激振荡电路通过运放构建,所述被测电容的变化转换成频率变化输出。 The capacitance detecting circuit as claimed in claim 1, wherein: the self-oscillating circuit is constructed by the operational amplifier, the measured capacitance variation is converted into the output frequency change.
  4. 4.如权利要求3所述的电容检测电路,其特征在于:所述电容频率转换电路包括运放、 积分电阻R、分压电阻R1、电阻R2、电阻R3,运放的输出电压经RC电路积分后送入运放的反响输入端,其反相输入端连接被测电容,运放输出电压经反馈电阻R3进入同相端,电源VCC 作为参考电压经Rl加到运放同相输入端。 4. The capacitance detecting circuit according to claim 3, wherein: said frequency conversion circuit comprises a capacitor operational amplifier, integrating resistor R, voltage-dividing resistor R1, a resistor R2, a resistor R3, the output voltage of the op amp via the RC circuit after integration into the response input terminal of operational amplifier inverting input terminal thereof is connected capacitance, the output voltage of the operational amplifier via a feedback resistor R3 noninverting terminal, a reference voltage supply VCC through Rl applied to the noninverting input of the op amp.
  5. 5.如权利要求4所述的电容检测电路,其特征在于:所述运放输入的周期T=2RCln ((R3+R2) /R3),振荡频率f为1/T,在R2、R3、R的阻值确定时,频率由电容C决定。 5. The capacitance detecting circuit according to claim 4, wherein: said op amp input period T = 2RCln ((R3 + R2) / R3), f is the oscillation frequency 1 / T, in R2, R3, when the resistance R is determined, the frequency determined by the capacitance C.
  6. 6.电容式压力变送器,其特征在于:它包括电容检测电路、单片机、存储器、输入设备和显示单元,电容检测电路包括:包括电容式压力传感器、多路开关和电容频率转换电路, 电容式压力传感器:用于将外界压力变化信号转换为电容变化值;多路开关:其输入端连接电容式压力传感器,其输出端连接电容频率转换电路,用于对两侧电容进行切换;电容频率转换电路:其为一自激振荡电路,用于对多路开关输出的北侧电容信号转换成频率信号; 单片机:用于对多路开关的控制以及接收电容频率转换电路送出的频率信号,并对其进行计算和转换;存储器:用于存储单片机产生的计算结果数据;输入设备:用于调整量程和输入测量参数;显示单元:勇于输出测量结果及所述参数设置的显示。 6. A capacitive pressure transducer, characterized in that: it comprises a capacitance detection circuit, microcontroller, memory, input devices and a display unit, a capacitance detecting circuit comprising: a capacitive pressure sensor, and a multi-way switch capacitance frequency conversion circuit, a capacitor pressure sensor: for external pressure change signal is converted to a capacitance variation value; multiplexer: an input terminal connected to the capacitive pressure sensor having an output capacitor connected to the frequency converting circuit, for both sides of the capacitor switching; capacitor frequency converting circuit: that is a self-oscillation circuit, for conversion into a frequency signal of capacitor north multiplexer output signal; microcontrollers: a circuit for converting the frequency of the signal sent to the control capacitor and receiving frequency multiplex switch, and its calculation and conversion; memory: means for storing the calculation result data generated by the microcontroller; input device: an input for adjusting the range and measurement parameters; display unit: bold and outputs the measurement result of the parameter settings.
  7. 7.如权利要求6所述的电容式压力变送器,其特征在于:所述被测电容与滞回比较器相连构成自激振荡器电路,所述振荡频率的大小体现被测电容的大小。 7. A capacitive pressure transducer as claimed in claim 6, wherein: said measured capacitance and hysteresis comparator connected to constitute a self-excited oscillator circuit, the oscillation frequency reflects the size of the size of the measured capacitance .
  8. 8.如权利要求6所述的电容式压力变送器,其特征在于:自激振荡回路通过运放构建, 所述被测电容的变化转换成频率变化输出。 8. A capacitive pressure transducer as claimed in claim 6, wherein: the self-oscillating circuit constructed by the operational amplifier, the measured capacitance variation is converted into the output frequency change.
  9. 9.如权利要求8所述的电容式压力变送器,其特征在于:所述电容频率转换电路包括运放、积分电阻R、分压电阻R1、电阻R2、电阻R3、运放的输出电压经RC电路积分后送入运放的反相输出端,其反相输出端连接被测电容,运放输出电压经反馈电阻R3进入同相端, 电源VCC作为参考电压经Rl加到运放同相输入端。 9. A capacitive pressure transducer as claimed in claim 8, wherein: said frequency conversion circuit comprises a capacitor operational amplifier, integrating resistor R, voltage-dividing resistor R1, a resistor R2, a resistor R3, the output voltage of the op amp after integrating RC circuit is fed to the inverting operational amplifier output terminal, an inverting output terminal connected to capacitance, the output voltage of the operational amplifier via a feedback resistor R3 noninverting terminal, a reference voltage power source VCC applied by Rl-inverting input of op amp end.
  10. 10.如权利要求6所述的电容式压力变送器,其特征在于:它包括电容检测电路、单片机、存储器、输入设备和显示单元,电容检测电路包括电容式压力传感器、多路开关及电容频率转换电路,其中,电容式压力传感器包括高压侧测压电容和低压侧测压电容,利用多路开关进行切换以及利用电容频率转换电路实现分时采样,并将采样值C经过转换成频率信号,其中,电容式压力传感器:用于将外界压力变化信号转换为电容变化值;多路开关:其第一输入端连接单片机P3. 3 口,控制高压侧测压电容与反馈电阻Rl—端的通断;第二输入端连接单片机P3.0 口,控制低压侧测压电容与反馈电阻Rl—端的通断;第三输入端连接单片机P3. 1 口,控制精密电容Cl与反馈电阻Rl—端的通断;第四输入端连接单片机P3. 2 口,控制插座)(Z5的一端与反馈电阻Rl —端的通断;电容频 10. A capacitive pressure transducer as claimed in claim 6, characterized in that: it comprises a capacitance detection circuit, microcontroller, memory, input devices and the display unit, the capacitance detection circuit comprises a capacitive pressure sensor, a multiplexer and a capacitor a frequency conversion circuit, wherein the capacitive pressure sensor comprising a high pressure side and a low side load capacitance load capacitance, multi-button switches and the use of capacitance-frequency conversion circuit to achieve time-sampled and the sampled value is converted into a frequency signal through C wherein the capacitive pressure sensor: means for converting the external pressure change signal to change the capacitance value; multi-way switch: a first input terminal connected to the microcontroller P3 3 port to control the high pressure side load capacitance of the feedback resistor terminal through Rl- break; a second input terminal connected to the microcontroller port P3.0, control the low side load capacitance of the feedback resistor Rl--off end; a third input connected to the microcontroller port P3 1, the control precision feedback resistor capacitor Cl through Rl- end. break; fourth input terminal connected to the microcontroller P3 2 port control socket) end (Z5 of the feedback resistor Rl - off end; capacitive frequency 率转换电路:采用运放和锁存器来构建自激振荡电路,它包括运放1、运放2、分压电阻R2、电阻R3、电阻R4、反馈电阻R1、与非门1、与非门2、滤波电容C14、电容C15、计数器1和计数器2,VCC经Rl加到运放1的同相输入端,再经R3加到运放2的反相输入端,最后经R4到地;运放1的同相输入端和运放2 的反相输入端分别接滤波电容C14,电容C15到地;运放1的输出端同与非门2的一个输入端相连,与非门2的另一输入端同与非门1的输出端相连,与非门2的输出端同与非门1的一个输入端相连,与非门1的另一个输入端与运放2的输出端相连,运放1的输出还与计数器1的时钟驱动输入端,反馈电阻Rl的一端相连;反馈电阻的另一端与多路开关的四个输入端、运放1的反相输入端及运放2的同相输入端相连;计数器1的第四位输出端与计数器2的时钟驱动输入端相连,计数器2的第二位 Rate converting circuit: using the operational amplifier and a latch constructed self-oscillating circuit comprising an operational amplifier, op amp 2, voltage dividing resistor R2, a resistor R3, a resistor R4, a feedback resistor R1, a NAND gate, and the non- the door 2, the filter capacitor C14, capacitor C15, the counter 1 and counter 2, the VCC applied to the op amp by Rl noninverting input terminal 1, and then added by R3 operational amplifier inverting input terminal 2, and finally to the ground by R4; Yun put the inverting input terminal and an inverting input terminal of the operational amplifier 2 are connected to filter capacitor C14, capacitor C15 to ground; an output terminal of the op amp with an input terminal of a NAND gate 2 is connected to the other NAND gate 2 with an input terminal and an output terminal of the NAND gate 1 is connected to an output terminal connected to one input terminal of the NAND gate NAND gate 2 with 1, 2 is connected to the output terminal of the NAND gate and the other input terminal of the operational amplifier 1, the operational amplifier 1 also outputs the clock input terminal of the counter drive 1, is connected to one end of the feedback resistor Rl; and the other end of the four inputs of the multiplexer feedback resistor switch, an operational amplifier and the inverting input terminal of op amp inverting input 2 terminal coupled; driving a clock input terminal coupled to the fourth output terminal of the counter 2 of the counter, the second counter is 2 第三位输出端与单片机的Pl. 2 口、Pl. 3 口相连;电源:3. 3V锂电池供电,主控制器电路板中使用3. 3V转3V可控开关芯片对模拟部分和数字部分提供所需的电源;3. 3V电源由C3、C14、C15、C16、C20、C21、C22、C24滤波,3V电源由Cl、C9、CIO、C18滤波;单片机:选用美国德州电气公司的MSP430F149芯片;晶振选用3. 6264MHz,程序下载使用标准JTAG接口;XT2IN、XT20UT与晶振连接,之间连接电阻R17, 经过C1UC12到地;MCU的54、55、56、57脚分别与双排座JP2的1、3、5、7脚相连,MCU的12 和22脚分别与JP2的2脚和6脚相连,MCU的58脚与JP2的11脚相连;EEPROM存储器: 片外存储芯片选用Microchip公司的MLC64芯片,采用I2C接口;由3. 3V电源供电,5、6 号管脚通过R20、R21上拉电阻与MCU的P4. 5、Ρ4· 6 口相连,C25用于滤波,1、2、3、4号脚接地用于指示物理地址;显示器:选用SPI总线结构的48管脚ΗΤ1621Β .. Pl is the third output of the microcontroller 2, Pl 3 connected; Power: switch chip analog and digital sections. 3 3V lithium battery, the main controller circuit board using 3. 3V 3V controllable switch. to provide the desired power; 3 3V powered by C3, C14, C15, C16, C20, C21, C22, C24 filtering, 3V powered by Cl, C9, CIO, C18 filtering; SCM: Texas electric company selected chip MSP430F149 ; crystal selection 3. 6264MHz, using the standard JTAG interface program download; XT2IN, XT20UT the crystal is connected, is connected between the resistor R17, to ground through C1UC12; 54,55,56,57 feet of the MCU, respectively double seat 1 of JP2 , 3,5,7 foot connected, the MCU 12 and the pin 22 connected to pin 2 of JP2 and 6 feet, respectively, the MCU 58 is connected to the foot 11 of the foot JP2; the EEPROM memory: off-chip memory chip used Microchip's chip MLC64 , using the I2C interface; a 3. 3V supply, 5,6 pins through R20, and the pull-up resistor on the MCU P4 5 R21, is connected to port Ρ4 · 6, C25 for filtering, 1,2,3,4. No. grounding pin is used to indicate the physical address; display: selection pin 48 ΗΤ1621Β SPI bus structure 动液晶屏幕,其中SEGO〜SEG23和COMO〜COM3共M个管脚与液晶玻璃连接,DATA管脚接上拉电阻R52的一端再与MCU的P5. 1 口连接,CS管脚接上拉电阻R53的一端再与MCU的Pl. 5 口连接,WR 管脚接上拉电阻R54的一端再与MCU的Pl. 6 口连接,RD管脚接上拉电阻R55的一端再与MCU的Pl. 7 口连接,上拉电阻R52、R53、R54、R55的另一端与VDD连接,VDD与VLCD管脚之间连接R51可变电阻,VDD与VSS分别于主控制器电路板上的3. 3V电源和地线连接,其余管脚悬空;无线通信:MCU的P3. 4、P3. 5 口与WIAPA-M1800无线通信模块的串口接口相连。 Moving the LCD screen, and wherein SEGO~SEG23 COMO~COM3 M pins were connected to the LCD glass, DATA pin is connected to one end of the pull-up resistor R52 P5 and then the MCU. A connection, the CS pin pull-up resistor R53 end of Pl and then the MCU. 5 is connected, WR pin pull-up resistor R54, one end of Pl and then the MCU. 6 is connected, RD pin of the pull-up resistor R55 at one end and then the MCU Pl. 7 connection, pull-up resistors R52, R53, R54, R55 and the other end is connected to VDD, a variable resistor R51 connected between pin VDD and VLCD, VDD and VSS, respectively, to the main controller circuit board 3. 3V supply and ground line is connected, the remaining pin is floating; wireless communication:.. MCU of P3 4, P3 5 port to the serial port WIAPA-M1800 wireless communication module.
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CN103575306A (en) * 2013-11-18 2014-02-12 东南大学 Passive wireless multi-parameter sensor system and multi-parameter measurement method thereof
CN103674352A (en) * 2013-12-18 2014-03-26 惠州盛太克仪表有限公司 Pressure transmitter signal processing chip and capacitive differential pressure transmitter
CN104267746A (en) * 2014-09-26 2015-01-07 杭州墨锐机电科技有限公司 Large-caliber ultra-thin self-adaptation secondary mirror control system

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CN103575306A (en) * 2013-11-18 2014-02-12 东南大学 Passive wireless multi-parameter sensor system and multi-parameter measurement method thereof
CN103674352A (en) * 2013-12-18 2014-03-26 惠州盛太克仪表有限公司 Pressure transmitter signal processing chip and capacitive differential pressure transmitter
CN104267746A (en) * 2014-09-26 2015-01-07 杭州墨锐机电科技有限公司 Large-caliber ultra-thin self-adaptation secondary mirror control system
CN104267746B (en) * 2014-09-26 2017-02-15 杭州墨锐机电科技有限公司 One kind of a mirror control system

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