CN105092075A - High accuracy multi-channel temperature signal acquisition device - Google Patents
High accuracy multi-channel temperature signal acquisition device Download PDFInfo
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Abstract
The invention discloses a high accuracy multi-channel temperature signal acquisition device. When temperature measurement platinum resistors are used to measure temperature, the constant current of a constant current source is transmitted to each temperature measurement platinum resistor through a first group of analogue switches; the other end of each resistor is grounded; at the same time, a second group of analogue switches are employed to acquire the voltage at two ends of each temperature measurement platinum resistor so that four-wire system connection for each temperature measurement platinum resistor is realized; as no current exists between each pair of input ends of the second group of analogue switches and each resistor, that is, no resistance is generated, the lead resistance can be effectively eliminated and the temperature measurement accuracy can be improved; an analogue circuit part and a digital circuit part employ a photoisolator to perform fine isolation so as to guarantee achievement of higher measurement accuracy; the temperature measurement accuracy for a temperature measurement circuit reaches 0.004DEG C within the -100DEG C to 50DEG C temperature measurement scope, and the linearity for the temperature measurement circuit reaches 0.0135%; and the constant current source current is set as 9.8mA through an RJ711 precise alloy foil resistor so as to eliminate the self-heating effect of each temperature measurement resistor and guarantee that the voltage of the temperature measurement platinum resistor Pt100 is not too low.
Description
Technical field
The present invention relates to small-signal detection technique field, particularly relate to a kind of high precision multi way temperature signal pickup assembly.
Background technology
Temperature is physical parameter general and important in production run and scientific experimentation, the essential condition of high-quality, high yield, low consumption and safety in production, the prerequisite that temperature accurately controls is high-precision temperature survey just, therefore, high precision multi way temperature Signal Collection Technology, is applied widely in the fields such as electric power, chemical industry, oil and Aero-Space.
Existing technical method has: two-wire system measuring method makes actual measured value higher due to the additive error that conductor resistance brings, and is generally used in the less demanding occasion of measuring accuracy; Pt sensor and metering circuit couple together with 3 wires by the advantage of general bridge-type temperature measurement circuit exactly, the aequilateral conductor length of Pt sensor is added on the brachium pontis of both sides respectively, do the measuring error that can significantly reduce caused by conductor resistance like this, but can not measuring error be eliminated; The three-wire system temperature measuring circuit of two constant current source compositions, two constant current sources are low relative to a constant-current source circuit reliability, and require that two constant current source output currents are completely the same, require higher to the resistance value of two constant current sources.Existing technical method, does not accomplish to isolate completely to digital circuits section and artificial circuit part, is also just difficult to the precision improving thermometric.Existing high precision measuring temperature is mainly for less thermometric way.
Summary of the invention
In view of this, the invention provides a kind of high precision multi way temperature signal pickup assembly, lead resistance is eliminated by adopting four-wire system, digital circuits section and artificial circuit part completely isolated, higher temperature measurement accuracy can not only be reached, and the collection of multi way temperature signal can be completed by adopting two group analog switch.
A kind of temperature signal collection device, comprise single-chip microcomputer, photoisolator, constant current source, analog to digital converter, RFI wave filter, two groups of analog switches and n thermometric platinum resistance, described n is positive integer; The current output terminal of constant current source described in the input termination of first group of analog switch in described pair of group analog switch, one end of each output termination thermometric platinum resistance of first group of analog switch, the other end ground connection of all thermometric platinum resistance; Often pair of input end of second group of analog switch in described pair of group analog switch is connected on the two ends of a corresponding thermometric platinum resistance respectively, obtains the both end voltage of thermometric platinum resistance;
The output terminal of described second group of analog switch receives the input end of described data converter by RFI wave filter;
The numbering of one of them thermometric platinum resistance that described single-chip microcomputer is specified according to user, sends road by described photoisolator to described first group of analog switch and second group of analog switch and selects signal; Described first group of analog switch selects signal according to described road, and the thermometric platinum resistance of specifying to described user exports described steady current; The both end voltage of the temperature detecting resistance that described second group of analog switch selects signal user to be specified according to described road exports;
Described digital to analog converter issues described single-chip microcomputer after converting the simulating signal of the voltage of reception to digital signal; Described single-chip microcomputer obtains temperature signal according to the voltage signal of the thermometric platinum resistance received.
The model of described analog to digital converter is AD7714AN-5; Described pair of group analog switch comprises a set of, two cover or three covers; The number of described RFI wave filter is consistent with the tricks of described pair of group analog switch;
It is the MUX of CD4067 that first group of analog switch in the two group analog switch of each cover comprises 5 models, and wherein 1 is prime, and other 4 is rear class; It is the MUX of CD4097 that described second group of analog switch comprises 9 models, and wherein 8 is prime, and other 1 is rear class;
For first group of analog switch, the wherein current output terminal of the input termination constant current source of the CD4067 MUX of prime, 4 output terminals of the CD4067 MUX of prime connect the input end of 4 CD4067 MUX of rear class respectively, and the output terminal of 4 CD4067 MUX of this rear class respectively connects a pin of a thermometric platinum resistance;
For second group of analog switch, each pair of input pin of 8 CD4097 MUX of described prime respectively connects a thermometric platinum resistance, and 8 pairs of input pins of the CD4097 MUX of rear class connect the output pin of prime 8 CD4097 MUX respectively; The output terminal of rear class 1 CD4097 MUX connects a pair input end of described digital to analog converter AD7714AN-5 by a RFI wave filter;
The road of described single-chip microcomputer selects signal to comprise 6, and described photoisolator comprises driver that a model is 74AC273 and 6 models are the optocoupler of 4N49U; Wherein 6 input pins of described driver respectively access 1 road and select signal; 6 output pins that driver is corresponding connect an optocoupler respectively;
Rear 2 address strobe ends of CD4067 MUX by optocoupler access prime of signal are selected on described road, for control prime CD4067 MUX by steady current conducting to one of them output terminal n; Road select signal front 4 all by the address strobe end of 4 CD4067 MUX of optocoupler access rear class, described steady current exported to for controlling the rear class CD4067 MUX that is connected with output terminal n the temperature detecting resistance that user specifies;
Described road select in signal front 3 all by the address strobe end of 8 CD4097 MUX of optocoupler access prime, the voltage of this appointment temperature detecting resistance exports by the CD4097 MUX that the temperature detecting resistance for controlling to specify with user is connected; Road select signal rear 3 by the address strobe end of 1 CD4097 MUX of optocoupler access rear class, export the magnitude of voltage of the temperature detecting resistance of specifying to digital to analog converter for controlling this CD4097 MUX.
The model of described single-chip microcomputer is P89V51RD2FN.
The model of described analog to digital converter is AD7714AN-5, and SCK, MISO of single-chip microcomputer P89V51RD2FN are connected with DIN pin with SCLK, DOUT of analog to digital converter AD7714-5 respectively by build-out resistor with MOSI pin; Described single-chip microcomputer passes through SCK pin to described SCLK tranmitting data register signal, the voltage signal data that the DOUT pin receiving analog to digital converter by MISO pin sends, sends gain, picking rate and startup, finishing control signal by MOSI pin to the DIN pin of analog to digital converter.
Described thermometric platinum resistance selects platinum resistance Pt100.
Described output type constant current source is made up of source of stable pressure AD584 and operational amplifier OP270, and constant current source resistance adopts RJ711 type Precise Alloy paper tinsel resistor.
Described constant current source exports 0.8mA steady current.
The present invention has following beneficial effect:
(1) the present invention is when adopting thermometric platinum resistance to carry out thermometric, by first group of analog switch, the steady current of constant current source is flowed to described thermometric platinum resistance, resistance other end ground connection; Simultaneously, by second group of analog switch, thermometric platinum resistance both end voltage is gathered, achieve the four-wire system connection of thermometric platinum resistance, because each pair of second group of analog switch does not have electric current between input end and resistance, namely resistance is not produced, therefore, it is possible to effectively eliminate lead resistance, improve temperature measurement accuracy;
(2) artificial circuit part of temperature signal collection device of the present invention and digital circuits section adopt photoisolator well to isolate, thus guarantee to reach comparatively high measurement accuracy.This temperature measurement circuit temperature measurement accuracy in-100 DEG C ~ 50 DEG C temperature-measuring ranges reaches 0.004 DEG C, the linearity 0.0135%;
(3) constant current source electric current is set as 0.8mA by RJ711 type Precise Alloy paper tinsel resistor, can eliminate temperature detecting resistance self-heating effect, ensures that on thermometric platinum resistance Pt100, voltage can not be too small simultaneously.RJ711 temperature-coefficient of electrical resistance is 5ppm, and effectively reducing the drift of constant current source resistance temperature affects acquisition precision.
(4) by the gain of software design patterns analog to digital converter AD7714, do not introduce amplifying circuit resistance, thus to eliminate in amplifying circuit the drift of resistance temperature acquisition precision is affected.
(5) analog power in this temperature measurement circuit, reference voltage with in analog between be connected with 10uF tantalum electric capacity and 0.022uF electric capacity, for temperature measurement circuit provides stable power supply.
(6) this temperature measurement circuit utilizes analog switch cascade and hyperchannel AD to realize multiplexed signal sampling, and thermometric way reaches 192 tunnels, and volume weight is little.
(7) the thermometric way of this circuit has the property deleted, thermometric way, can just with a set of pair of group analog switch and a RFI wave filter below 64 tunnels; Thermometric way, on 65 road to 128 tunnels, can use the two group analog switches of two covers and two RFI wave filters; Thermometric way on 129 road to 192 tunnels, then needs use three to overlap two group analog switches and three RFI wave filters.Only need to change two tricks of group analog switch and the number of RFI wave filter, the other parts of this temperature measurement circuit are without the need to changing.
Accompanying drawing explanation
Fig. 1 is the theory diagram of temperature signal collection device of the present invention;
Fig. 2 is of the present invention pair of group analog switch schematic diagram;
Fig. 3 is single-chip microcomputer of the present invention and two group analog switch interface relationship figure;
Fig. 4 is single-chip microcomputer of the present invention and analog to digital converter interface relationship figure;
Fig. 5 is analog to digital converter schematic diagram of the present invention;
Fig. 6 is photoisolator schematic diagram of the present invention;
Fig. 7 is constant-current source circuit schematic diagram of the present invention;
Fig. 8 is of the present invention pair of group analog switch and analog to digital converter interface relationship figure;
Fig. 9 is RFI Filter Principle figure of the present invention.
Embodiment
To develop simultaneously embodiment below in conjunction with accompanying drawing, describe the present invention.
Temperature signal collection device of the present invention comprises single-chip microcomputer, photoisolator, thermometric platinum resistance, constant current source, two groups of analog switches, RFI wave filter and analog to digital converters.The model of described single-chip microcomputer is P89V51RD2FN, the model of analog to digital converter be AD7714AN-5, P89V51RD2FN and AD7714AN-5 all with SPI interface, use three-wire system communication, AD7714AN-5 with three pairs of differential input ends, available software design patterns gain and channel selecting; Described photoisolator is made up of driver 74AC273 and optocoupler 4N49U respectively; Described thermometric platinum resistance selects platinum resistance Pt100; Described output type constant current source is made up of source of stable pressure AD584 and operational amplifier OP270, and constant current source resistance adopts RJ711 type Precise Alloy paper tinsel resistor; Described pair of group analog switch is respectively the first group of analog switch be made up of CD4067 MUX and the second group of analog switch be made up of CD4097 MUX.The theory diagram of this temperature signal collection circuit as shown in Figure 1.
The principle of work of this thermometric platinum resistance is: the resistance of thermometric platinum resistance Pt100 changes along with temperature variation, the voltage of platinum resistance generation is flow through by measuring steady current, the resistance value of a certain moment platinum resistance can be tried to achieve, and the temperature of platinum resistance present position can be learnt according to the resistance of platinum resistance.
Thermometric platinum resistance Pt100 is as temperature sensor, and each thermometric platinum resistance forms a channel Temperature Measuring passage.Pt100 as shown in Figure 1 picks out four extension lines, is respectively a, b, c, d, and a and b is connected to Pt100 one end, and c and d is connected to the other one end of Pt100.Because the AIN input current of AD7714AN-5 is 1nA to the maximum, constant current source output current can not flow into AD7714AN-5.Constant current source electric current flow in analog through a lead-in wire, Pt100 platinum resistance, d lead-in wire, then measures voltage on Pt100 via b and the c lead-in wire of Pt100.Adopt the four-wire system mode of connection, effectively can reduce the impact of platinum resistance lead-in wire on measurement result, improve temperature measurement accuracy.
Described constant current source is output type constant current source, and export 0.8mA steady current, constant current source current settings is 0.8mA, is the self-heating effect in order to eliminate thermometric platinum resistance, avoids pressure drop in platinum resistance too small simultaneously and affects measuring accuracy.Constant current source is made up of source of stable pressure AD584 and operational amplifier OP270, and source of stable pressure AD584 provides+2.5V reference voltage, determines that the resistance R128 of constant current source output current size adopts the high-accuracy resistance of RJK711, affects acquisition precision to reduce the drift of resistance temperature.Constant-current source circuit schematic diagram as shown in Figure 7.Its annexation is: No. 1, No. 2 of AD584 are directly connected with No. 3 pins, for constant current source provides reference power supply after electric capacity C43 and C44 voltage regulation filtering.No. 1 pin of AD584 is connected by in-phase input end No. 3 pins of resistance R132 and OP270, No. 6 of OP270 are directly connected with No. 7 pins, resistance R133 is connected with between No. 3 and No. 7 pins, resistance R130 is connected with between No. 1 and No. 2 pins, No. 2 pins of resistance R131 mono-termination OP270, another termination in analog.
Single-chip microcomputer P89V51RD2FN is a 80C51 microcontroller, comprises the data RAM of 1024 bytes, comprises 64kBFlash, operating temperature range-40 DEG C ~+85 DEG C.
Select analog to digital converter to be a key, according to the requirement of temperature measurement accuracy and sample rate, select AD7714AN-5 as modulus conversion chip.This chip has register in eight sheets, by the programming to register in sheet, can realize the functions such as channel selecting, gain selection, frequency filtering selection, change-over period selection and AD conversion; There is the functions such as self calibration, system calibration and background calibration, zero-error can be eliminated like this, completely measure the impact of error and temperature drift.AD7714AN-5 is particularly suitable for low frequency, high-resolution A/D changes.Analog to digital converter peripheral circuit as shown in Figure 5.No. 1 of AD584 is directly connected with No. 2 pins, for AD7714AN-5 provides stable power supply after electric capacity C29 and C51 voltage regulation filtering.No. 2 pins of AD580 are voltage output end, for AD7714AN-5 provides reference voltage after electric capacity C30 and C31 voltage regulation filtering.The power supply of AD584 and AD580 is+12V, it is to be noted that+12V power supply is only for providing power supply for mimic channel.
P89V51RD2FN and AD7714, all with SPI interface, uses three-wire system communication, and P89V51RD2FN, by the DRDY position in the communication register of inquiry AD7714, judges whether analog to digital conversion completes.As shown in Figure 5, SCK, MISO, MOSI pin of P89V51RD2FN is connected respectively by SCLK, DOUT, DIN pin of build-out resistor R142, R143, R144 and AD7714 for P89V51RD2FN and AD7714 interface relationship.Single-chip microcomputer passes through SCK pin to described SCLK tranmitting data register signal, the voltage signal data that the DOUT pin receiving analog to digital converter by MISO pin sends, sends gain, picking rate and startup, finishing control signal by MOSI pin to the DIN pin of analog to digital converter.
Single-chip microcomputer P89V51RD2FN is connected with two group analog switch by photoisolator, and P89V51RD2FN and two group analog switch interface relationship figure are as shown in Figure 3.Photoisolator is made up of driver 74AC273 and optocoupler 4N49U, and photoisolator schematic diagram as shown in Figure 6.The suitable time-delay when programming, to meet the level Time Created of optocoupler in photoisolator.Two groups of analog switches are respectively the first group of analog switch be made up of CD4067 and the second group of analog switch be made up of CD4097.Two groups of analog switch schematic diagrams as shown in Figure 2.The first group of analog switch be made up of CD4067 be used for gating which connect constant current source electric current, the second group of analog switch be made up of CD4097 is used for the voltage signal at which thermometric platinum resistance two ends of gated acquisition.
Its annexation is: six pin P00 to P05 of single-chip microcomputer P89V51RD2FN are connected with six pin one D to 6D of driver 74AC273 respectively, and P27 and the WR pin of single-chip microcomputer P89V51RD2FN passes through or door 74AC32 is connected with the CLK pin of driver 74AC273.Six pin one Q to 6Q of driver 74AC273 are connected with No. 1 pin of six optocoupler 4N49U respectively through a resistance, in figure 6, have only marked an optocoupler 4N49U.No. 5 pins of six optocoupler 4N49U are connected with the address strobe end add0 to add5 of two groups of analog switches respectively.The first group of analog switch be made up of 5 CD4067 MUX, output terminal No. 1 pin of rear class four CD4067 MUX is connected respectively to the IO0 to IO3 of prime a slice CD4067.In fig. 2, CD4067 MUX in a slice rear class has only been marked.The second group of analog switch be made up of 9 CD4097 MUX, output terminal No. 1 pin (OUTA) of prime 8 CD4097 MUX is connected respectively to the IOA1 to IOA8 of rear class a slice CD4097 MUX, and output terminal No. 17 pins (OUTB) of prime 8 CD4097 MUX are connected respectively to the IOB1 to IOB8 of rear class a slice CD4097 MUX.In fig. 2, CD4097 in a slice prime has only been marked.
The model of described analog to digital converter is AD7714AN-5; Described pair of group analog switch comprises a set of, two cover or three covers; The number of described RFI wave filter is consistent with the group number of described pair of group analog switch; It is the MUX of CD4067 that first group of analog switch in the two group analog switch of each cover comprises 5 models, and wherein 1 is prime, and other 4 is rear class; It is the MUX of CD4097 that described second group of analog switch comprises 9 models, and wherein 8 is prime, and other 1 is rear class; The wherein current output terminal of the input termination constant current source of the CD4067 MUX of prime, 4 output terminals of the CD4067 MUX of prime connect the input end of 4 CD4067 MUX of rear class respectively, and the output terminal of 4 CD4067 MUX of this rear class respectively connects a pin of a thermometric platinum resistance;
For second group of analog switch, each pair of input pin of 8 CD4097 MUX of described prime respectively connects a thermometric platinum resistance, and 8 pairs of input pins of the CD4097 MUX of rear class connect the output pin of prime 8 CD4097 MUX respectively; The output terminal of rear class 1 CD4097 MUX connects a pair input end of described AD7714AN-5 by a RFI wave filter;
The road of described single-chip microcomputer selects signal to comprise 6, and described photoisolator comprises driver that a model is 74AC273 and 6 models are the optocoupler of 4N49U; Wherein 6 input pins of described driver respectively access 1 road and select signal; 6 output pins that driver is corresponding connect an optocoupler respectively;
Rear 2 address strobe ends of CD4067 MUX by optocoupler access prime of signal are selected on described road, for control prime CD4067 MUX by steady current conducting to one of them output terminal n; Road select signal front 4 all by the address strobe end of 4 CD4067 MUX of optocoupler access rear class, described steady current exported to for controlling the rear class CD4067 MUX that is connected with output terminal n the temperature detecting resistance that user specifies;
Described road select in signal front 3 all by the address strobe end of 8 CD4097 MUX of optocoupler access prime, the voltage of this appointment temperature detecting resistance exports by the CD4097 MUX that the temperature detecting resistance for controlling to specify with user is connected; Road select signal rear 3 by the address strobe end of 1 CD4097 MUX of optocoupler access rear class, export the magnitude of voltage of the temperature detecting resistance of specifying to digital to analog converter for controlling this CD4097 MUX.
Two groups of a set of analog switches can gating 64 tunnel, digital to analog converter AD7714 tri-differential input end AIN1 and AIN2, AIN3 and AIN4, AIN5 and AIN6, two groups of analog switches of corresponding three covers, totally 192 tunnels.The interface relationship figure of two groups of analog switches and analog to digital converter AD7714 as shown in Figure 8.Its annexation is: the output terminal of the CD4097 MUX in first set, after corresponding RFI wave filter, is connected with digital to analog converter AD7714 differential input end AIN1, AIN2; The output terminal of the CD4097 MUX in the second cover, after corresponding RFI wave filter, is connected with digital to analog converter AD7714 differential input end AIN3, AIN4; The output terminal of the CD4097 MUX in the 3rd cover, after corresponding RFI wave filter, is connected with digital to analog converter AD7714 differential input end AIN5, AIN6.
The thermometric way of temperature measurement circuit provided by the invention has the property deleted, thermometric way, can just with two groups of a set of analog switches and a RFI wave filter below 64 tunnels; Thermometric way, on 65 road to 128 tunnels, can use two groups of analog switches and two RFI wave filters of two covers; Thermometric way on 129 road to 192 tunnels, then the two groups of analog switches needing use three to overlap and three RFI wave filters.Only need to change two tricks of group analog switch and the number of RFI wave filter, the other parts of this temperature measurement circuit are without the need to changing.
The wave filter that RFI wave filter is made up of bridge diagram, this wave filter suppresses RFI except providing, and also provides additional input overload protection, because resistor R1a and R1b helps the input circuit of instrument amplifier and outside source to isolate.RFI Filter Principle figure as shown in Figure 9.Its annexation is: electric capacity C45 is connected across bridge output, electric capacity C46 mono-termination C45, and in analog, electric capacity C47 mono-termination C45, in analog, RFI filter input end and output terminal are connected to resistance R124 and R125 to another termination to another termination.
In Software for Design, adjacent three temperature acquisition values taken the mean, in-100 DEG C ~ 50 DEG C temperature-measuring ranges, temperature measurement accuracy can reach 0.002 DEG C.
In sum, these are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (7)
1. a temperature signal collection device, is characterized in that, comprise single-chip microcomputer, photoisolator, constant current source, analog to digital converter, RFI wave filter, two groups of analog switches and n thermometric platinum resistance, described n is positive integer; The current output terminal of constant current source described in the input termination of first group of analog switch in described pair of group analog switch, one end of each output termination thermometric platinum resistance of first group of analog switch, the other end ground connection of all thermometric platinum resistance; Often pair of input end of second group of analog switch in described pair of group analog switch is connected on the two ends of a corresponding thermometric platinum resistance respectively, obtains the both end voltage of thermometric platinum resistance;
The output terminal of described second group of analog switch receives the input end of described data converter by RFI wave filter;
The numbering of one of them thermometric platinum resistance that described single-chip microcomputer is specified according to user, sends road by described photoisolator to described first group of analog switch and second group of analog switch and selects signal; Described first group of analog switch selects signal according to described road, and the thermometric platinum resistance of specifying to described user exports described steady current; The both end voltage of the temperature detecting resistance that described second group of analog switch selects signal user to be specified according to described road exports;
Described digital to analog converter issues described single-chip microcomputer after converting the simulating signal of the voltage of reception to digital signal; Described single-chip microcomputer obtains temperature signal according to the voltage signal of the thermometric platinum resistance received.
2. temperature signal collection device as claimed in claim 1, it is characterized in that, the model of described analog to digital converter is AD7714AN-5; Described pair of group analog switch comprises a set of, two cover or three covers; The number of described RFI wave filter is consistent with the tricks of described pair of group analog switch;
It is the MUX of CD4067 that first group of analog switch in the two group analog switch of each cover comprises 5 models, and wherein 1 is prime, and other 4 is rear class; It is the MUX of CD4097 that described second group of analog switch comprises 9 models, and wherein 8 is prime, and other 1 is rear class;
For first group of analog switch, the wherein current output terminal of the input termination constant current source of the CD4067 MUX of prime, 4 output terminals of the CD4067 MUX of prime connect the input end of 4 CD4067 MUX of rear class respectively, and the output terminal of 4 CD4067 MUX of this rear class respectively connects a pin of a thermometric platinum resistance;
For second group of analog switch, each pair of input pin of 8 CD4097 MUX of described prime respectively connects a thermometric platinum resistance, and 8 pairs of input pins of the CD4097 MUX of rear class connect the output pin of prime 8 CD4097 MUX respectively; The output terminal of rear class 1 CD4097 MUX connects a pair input end of described digital to analog converter AD7714AN-5 by a RFI wave filter;
The road of described single-chip microcomputer selects signal to comprise 6, and described photoisolator comprises driver that a model is 74AC273 and 6 models are the optocoupler of 4N49U; Wherein 6 input pins of described driver respectively access 1 road and select signal; 6 output pins that driver is corresponding connect an optocoupler respectively;
Rear 2 address strobe ends of CD4067 MUX by optocoupler access prime of signal are selected on described road, for control prime CD4067 MUX by steady current conducting to one of them output terminal n; Road select signal front 4 all by the address strobe end of 4 CD4067 MUX of optocoupler access rear class, described steady current exported to for controlling the rear class CD4067 MUX that is connected with output terminal n the temperature detecting resistance that user specifies;
Described road select in signal front 3 all by the address strobe end of 8 CD4097 MUX of optocoupler access prime, the voltage of this appointment temperature detecting resistance exports by the CD4097 MUX that the temperature detecting resistance for controlling to specify with user is connected; Road select signal rear 3 by the address strobe end of 1 CD4097 MUX of optocoupler access rear class, export the magnitude of voltage of the temperature detecting resistance of specifying to digital to analog converter for controlling this CD4097 MUX.
3. temperature signal collection device as claimed in claim 1, it is characterized in that, the model of described single-chip microcomputer is P89V51RD2FN.
4. temperature signal collection device as claimed in claim 3, it is characterized in that, the model of described analog to digital converter is AD7714AN-5, and SCK, MISO of single-chip microcomputer P89V51RD2FN are connected with DIN pin with SCLK, DOUT of analog to digital converter AD7714-5 respectively by build-out resistor with MOSI pin; Described single-chip microcomputer passes through SCK pin to described SCLK tranmitting data register signal, the voltage signal data that the DOUT pin receiving analog to digital converter by MISO pin sends, sends gain, picking rate and startup, finishing control signal by MOSI pin to the DIN pin of analog to digital converter.
5. temperature signal collection device as claimed in claim 1, it is characterized in that, described thermometric platinum resistance selects platinum resistance Pt100.
6. temperature signal collection device as claimed in claim 1, it is characterized in that, described output type constant current source is made up of source of stable pressure AD584 and operational amplifier OP270, and constant current source resistance adopts RJ711 type Precise Alloy paper tinsel resistor.
7. temperature signal collection device as claimed in claim 6, is characterized in that, described constant current source exports 0.8mA steady current.
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| CN112763089A (en) * | 2020-12-24 | 2021-05-07 | 西安翔腾微电子科技有限公司 | Intelligent current sensor signal conditioning method and conditioning circuit thereof |
| CN112798130A (en) * | 2020-12-30 | 2021-05-14 | 浙江启尔机电技术有限公司 | Multi-path temperature measuring device and multi-path temperature measuring circuit thereof |
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| CN112595428A (en) * | 2021-01-05 | 2021-04-02 | 苏州全谱仪器科技有限公司 | Measuring circuit and method of three-wire system resistance sensor |
| CN113885632A (en) * | 2021-10-29 | 2022-01-04 | 西安微电子技术研究所 | Aerospace high-precision constant current source circuit |
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