CN203908566U - Multi-way soil pressure sensor based on optical fiber transmission - Google Patents

Abstract

The utility model discloses a multi-way soil pressure sensor based on optical fiber transmission, and the sensor comprises a single-chip microcomputer. The input port of the single-chip microcomputer is connected with an A/D converter. The input end of the A/D converter is sequentially connected with an instrument amplifier, and a multi-way bridge strain gage switching circuit. The output port of the single-chip microcomputer is connected with a communication interface chip. When the above structure is employed, an electric signal detected by the sensor is collected, quantized and encoded into a digital signal after passing through the A/D converter. The processed electric signal can be transmitted in a short-distance or far-distance manner conveniently and reliably through the communication interface chip.

Description

A kind of multichannel soil pressure case based on Optical Fiber Transmission

Technical field

The utility model belongs to electronic circuit field, is specifically related to a kind of sensor signal processing circuit.

Background technology

In soil pressure experiment, because experimental situation is severe, the Obtaining Accurate of soil pressure signal is very very difficult, and the processing of follow-up data need to draw above on the basis of signal and carry out, so the transmission precision of signal is had to higher requirement.

The transmission of the existing data that sensor in soil pressure test is detected generally in the following way, directly the signal detecting from sensor is transmitted by the mode of data line, adopt which can only carry out short range transmission, transmission range is wanted in 2 meters, and the meeting over 2 meters causes the distortion of signal.Adopt which exist distant signal can not be reliable, the problem of undistorted transmission.

Summary of the invention

Technical problem to be solved in the utility model is for above-mentioned the deficiencies in the prior art, and a kind of signal that sensor can be detected providing is reliable, undistorted closely, the sensor signal processing circuit of long-distance transmissions.

The purpose of this utility model is achieved in that

A multichannel soil pressure case based on Optical Fiber Transmission, it comprises single-chip microcomputer, and the input port of single-chip microcomputer is connected with AD converter, and AD converter is connected with instrument amplifier, and instrument amplifier is connected with multichannel bridge-type foil gauge commutation circuit; The delivery outlet of single-chip microcomputer is connected with communication interface chip.

Above-mentioned communication interface chip is the interface chip based on RS485 agreement.

The above-mentioned interface chip based on RS485 agreement is connected with optic module.

Above-mentioned multichannel bridge-type foil gauge commutation circuit comprises foil gauge and analog switch, and foil gauge is connected with analog switch, and analog switch is connected with instrument amplifier.

Above-mentioned foil gauge is 8 road foil gauges, and 8 road foil gauges connect and compose bridge circuit with analog switch respectively.

The utility model has been obtained following technique effect:

While adopting said structure, the electric signal that sensor detects after AD converter by single-chip microcomputer collection, quantize, be encoded into digital signal, electric signal so after treatment just can pass through communication interface chip convenient, reliably closely or at a distance to be transmitted;

Adopting communication interface chip be the structure of the interface chip based on RS485 agreement, and RS485 has larger communication distance and the good anti-noise jamming of energy on the basis of transfer rate faster;

The structure that the interface chip of employing based on RS485 agreement is connected with optic module, is transmitted and can be converted the electrical signal to light signal by optical fiber, thus realize signal farther and more reliably transmission;

Adopt multichannel bridge-type foil gauge commutation circuit to comprise foil gauge and analog switch, foil gauge is connected with analog switch, the structure that analog switch is connected with instrument amplifier, each independent foil gauge is connected and can forms bridge circuit with analog switch, a plurality of like this foil gauges can be used same bridge circuit, reduce number of elements, simplified signal processing circuit;

Adopting foil gauge is 8 road foil gauges, and 8 road foil gauges connect and compose respectively the structure of bridge circuit with analog switch, and need to optionally access when No. 8 sensors can be according to experiment is more convenient to use, practical.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the utility model is described in further detail.

Fig. 1 is structured flowchart of the present utility model;

Fig. 2 is the circuit diagram of multichannel bridge-type foil gauge commutation circuit in the utility model;

Fig. 3 is the circuit diagram of communicating circuit in the utility model;

Fig. 4 and Fig. 5 are the circuit diagram of mu balanced circuit in the utility model.

Embodiment

A multichannel soil pressure case based on Optical Fiber Transmission as shown in Figure 1, it comprises single-chip microcomputer 1, and the input port of single-chip microcomputer 1 is connected with AD converter, and AD converter is connected with instrument amplifier 3, and instrument amplifier 3 is connected with multichannel bridge-type foil gauge commutation circuit 2; The delivery outlet of single-chip microcomputer 1 is connected with communication interface chip 4, and communication interface chip 4 is the interface chip based on RS485 agreement, and the model of selecting single-chip microcomputer is ATMEGA16.

Preferably, single-chip microcomputer 1 is connected with voltage-stabilized power supply circuit 6.

The described interface chip based on RS485 agreement is by being connected with optic module 5, can realize the farther and transmission more reliably of signal.

As shown in Figure 2, multichannel bridge-type foil gauge commutation circuit comprises foil gauge and analog switch, and foil gauge is connected with analog switch, and analog switch is connected with instrument amplifier 3; Described foil gauge is 8 road foil gauges, and 8 road foil gauges connect and compose bridge circuit with analog switch respectively.

Analog switch adopt two ADG411 analog channel chips to 8 road and bridge formula foil gauge circuit switch, the signal at bridge circuit the two poles of the earth carries out the amplification of voltage signal by instrument amplifier INA128, voltage signal can be processed by single-chip microcomputer;

This circuit is by 8 foil gauge S0, S1, S2, S3, S4, S5, S6, S7,2 analog channels are switched chip U1, U2(ADG411) and instrument amplifier AR1(INA128) form, resistance R 0, R1, R2, R3, R4, R5, R6, R7, R9, R10, capacitor C 3, C11 form.Foil gauge S0 ~ S7 mono-termination 5V power supply, the other end receives ground by resistance R 0 ~ R7.Take S0, R0 as example, between foil gauge S0 and resistance R 0, by connection, arrive analog switch U1(ADG411) No. 3 pins (No. 0 passage of corresponding U1), after this passage is opened, No. 3 and No. 2 pins connections of U1, No. 2 pin is connected to instrument amplifier AR1(INA128) No. 2 pins, now S0, R1 and R8, R9 form a bridge circuit.2, No. 3 pins of instrument amplifier AR1 are received at the two poles of the earth of bridge circuit.In like manner, remaining foil gauge has been received respectively 1 ~ No. 7 passage of U1, the U2 of analog channel, and when respective channel is opened, corresponding foil gauge, resistance and R8, R9 form bridge circuit.Analog switch U1, U2, be subject to single chip computer AT MEGA16 and control, and 1,8,9, No. 16 controlled pin of U1 and U2 is connected with the PC0 ~ PC7 of single-chip microcomputer respectively, correspondence 0 ~ 7 passage.The two poles of the earth that 2, No. 3 pins of instrument amplifier AR1 are received respectively bridge circuit, when foil gauge is under pressure and when resistance occurring changing, two arms of bridge circuit are balance again, can produce the voltage signal of subtle change, voltage signal amplifies by instrument amplifier, and formation can be adopted the voltage signal of being accepted by Chip Microcomputer A/D, and instrument amplifier can regulate all multiples that reaches by resistance R 10, in this circuit, this value is through being calculated as 235 Ω.Capacitor C 3, C11 are power filtering capacitor, prevent that in power supply, noise causes interference to signal, to improve the precision of signal.

As shown in Figure 3, this circuit is by single chip computer AT MEGA16, and USART turns 485 protocol chip MAX485CPA, diode DOU1(IN4007), resistance R 36, R37, R43, R44, capacitor C 26, C30, C40, C43, C44, C45, inductance L 3, L4 form.PC0 ~ the PC7 of single-chip microcomputer is connected to 1,8,9, No. 16 pin of analog channel U1, U2 in Fig. 2, as passage, switch and use, PA0(multiplexing pins AD0) be connected to No. 6 pins of the instrument amplifier AR1 in Fig. 2, as AD, adopt, PD0, PD1(multiplexing pins RXD, TXD, the output terminal of serial communication USART) receive 1, No. 4 pin of protocol conversion chip MAX485CPA, for carrying out message exchange transmission with MAX485CPA, PD2 receives 2, No. 3 pins of MAX485CPA, and monolithic is controlled MAX485CPA by this pin and opened or closed.R43, R37 are for improving the impedance of 485 signal wires, avoid occurring wave reflection, the anti-stop signal of both positive and negative polarity that diode DOU1 anode and negative electrode are connected respectively to 485 signal wires impacts, resistance R 39 is pull-up resistors of 485 anodal circuits, R44 is the pull down resistor of 485 signal wires, and C26, C30 are 5V power filters.R36 mono-end is received 5V power supply, and one end is by capacitor C 43 ground connection, and receive on the RESET pin of single-chip microcomputer the junction of resistance and electric capacity, is for resetting for single-chip microcomputer.Inductance L 4 is AGND and digitally the isolation inductance of GND in analog, and its resistance is zero.Inductance L 3, L5, capacitor C 40, C41, C44, C45 are for single-chip microcomputer 5V power supply is carried out to filtering.If for 2 ~ 200 meters of short-distance transmission, directly can use 485 signal wires, if for long-distance transmissions more, signal wire can be connected with optic module, electric signal be transformed into light signal and transmit.

Voltage-stabilized power supply circuit comprises 5V booster circuit as shown in Figure 4, and-5V translation circuit as shown in Figure 5.

As shown in Figure 4, externally fed input terminal P1, input voltage range is 3V ~ 9V, P1 input voltage converts chip MAX770 by DC-DC and converts to and stablize 5V voltage, 5V booster circuit comprises MAX770, inductance L 2, triode Q2, diode D3, capacitor C 7, C10, C15, C18, resistance R 13;

As shown in Figure 5,5V voltage is again by be transformed into-5V of DC-DC conversion chip MAX764, and-5V translation circuit comprises MAX764, inductance L 1, diode D1, capacitor C 2, C3, C4, C5.

While adopting said structure, the electric signal that sensor detects after AD converter by single-chip microcomputer collection, quantize, be encoded into digital signal, electric signal so after treatment just can pass through communication interface chip convenient, reliably closely or at a distance to be transmitted.

Claims (3)

1. the multichannel soil pressure case based on Optical Fiber Transmission, it comprises single-chip microcomputer (1), it is characterized in that: the input port of single-chip microcomputer (1) is connected with AD converter, AD converter is connected with instrument amplifier (3), and instrument amplifier (3) is connected with multichannel bridge-type foil gauge commutation circuit (2); The delivery outlet of single-chip microcomputer (1) is connected with communication interface chip (4); Multichannel bridge-type foil gauge circuit (2) comprises foil gauge and analog switch, foil gauge is connected with analog switch, analog switch is connected with instrument amplifier (3), foil gauge is 8 road foil gauges, analog switch has 2,8 road foil gauges are respectively S0, S1, S2, S3, S4, S5, S6, S7,8 road foil gauges are at one end respectively by resistance R 0, R1, R2, R3, R4, R5, R6, R7 ground connection, 8 road foil gauge S0-S7 are connected with 2 analog switches, resistance R 8, R9 after being connected with 8 resistance R 0-R7 successively, and form bridge circuit.

2. the multichannel soil pressure case based on Optical Fiber Transmission according to claim 1, is characterized in that: described communication interface chip (4) is the interface chip based on RS485 agreement.

3. the multichannel soil pressure case based on Optical Fiber Transmission according to claim 2, is characterized in that: the described interface chip based on RS485 agreement is connected with optic module (5).