CN210090557U

CN210090557U - Digital frequency meter with dual-mode wireless transmission function

Info

Publication number: CN210090557U
Application number: CN201920398712.1U
Authority: CN
Inventors: 蒋琳; 高燕
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2019-03-27
Filing date: 2019-03-27
Publication date: 2020-02-18
Anticipated expiration: 2029-03-27

Abstract

The utility model relates to a digital frequency meter with double mode wireless transmission function, including switch selection circuit, amplifier circuit, shaping circuit, NE555 square wave generating circuit, FPGA control circuit, AT89C52R singlechip, wireless communication module, display circuit, the utility model discloses multiple mode has, the mode is one: when the switch selection circuit selects an external frequency measurement mode, an external measured signal is connected to the input end of the amplification circuit, the amplified signal is subjected to frequency measurement through the FPGA control circuit after being output by the shaping circuit, the single chip microcomputer completes processing in the aspect of man-machine interaction and system control, measured frequency information is uploaded to terminal equipment such as a computer or a mobile phone through the wireless transmission module, and the measured frequency information is directly displayed through a 6-bit nixie tube in the display circuit. And a second mode: the square wave that NE555 square wave generating circuit produced exports after a series of processings as signal input, compares with prior art, the utility model has the advantages of multifunctional mode, small, measurement accuracy.

Description

Digital frequency meter with dual-mode wireless transmission function

Technical Field

The present invention relates to a frequency meter, and more particularly to a digital frequency meter having a dual mode wireless transmission function.

Background

In the field of electronic technology, frequency is an important parameter of an electrical signal, and refers to the number of times that an electronic device completes periodic variation per unit time. A frequency meter is used to measure the signal to be measured. Measuring the signal frequency is of great significance in engineering. The frequency meters produced in the market at present are various in types, but have limitations, such as high price, large size, single measurement mode, low measurement precision and the like, and in some occasions, the size of the frequency meter is required to be as small as possible, the frequency meter is economical and practical, particularly, most oscilloscopes which are practical in teaching experiments are used for frequency measurement, the size is clumsy and expensive, and the cost is too high for some simple frequency measurement teaching. With the development of internet technology, wireless communication is becoming a trend, and how to transmit measured frequency information to terminal devices such as mobile phones and computers by using a small portable frequency meter is also a focus of attention of the present invention.

The invention aims to design a human-computer interaction type, small and convenient wireless transmission frequency meter. The frequency meter has two frequency measurement modes for user selection. The user can measure the external frequency mode, and can also use the square wave generating circuit carried by the user to carry out the frequency measuring mode, and the measured frequency is adjusted by the user. The application range is from working frequency measurement to outdoor frequency measurement, and even teaching experiments. The frequency division shaping module reduces errors of measurement results and improves precision. The measured frequency can be transmitted to terminal equipment such as a mobile phone computer and the like through a wireless transmission module, so that a large amount of data can be stored and analyzed.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a digital frequency meter with double mode wireless transmission function in order to overcome the defect that above-mentioned prior art exists, this frequency meter has two kinds of frequency measurement modes, both can solve laboratory instrument operation complicacy, produce with its self inherent square wave and can hand-carry and be used for measuring also can carry out the frequency measurement through outside frequency measurement signal, frequency division shaping circuit makes the frequency division more meticulous, the frequency measurement error is littleer, precision frequency measurement such as FPGA further improves measurement accuracy, still solve the manual record of data with wireless communication module, save complicated problem in a large number.

The purpose of the utility model can be realized through the following technical scheme:

a digital frequency meter with a dual-mode wireless transmission function comprises a switch selection circuit, an external measured signal, an NE555 square wave generation circuit, an amplification circuit, a shaping circuit, an FPGA control circuit, a display circuit and a wireless communication module, wherein the switch selection circuit can be connected with the FPGA control circuit through a signal transmission path I or a signal transmission path II, measures frequency and then is connected with the display circuit for displaying a measurement result and the wireless communication module for wireless data transmission through a single chip microcomputer;

the first signal transmission path comprises the external tested signal, the amplifying circuit and the shaping circuit which are sequentially connected, and the first signal transmission path is correspondingly connected with the switch selection circuit and the FPGA control circuit through the external tested signal and the shaping circuit respectively;

the second signal transmission path comprises the NE555 square wave generating circuit and the amplifying circuit which are sequentially connected, and the second signal transmission path is correspondingly connected with the switch selection circuit and the FPGA control circuit through the NE555 square wave generating circuit and the amplifying circuit respectively.

Furthermore, the NE555 square wave generating circuit comprises an NE555 chip, THR pins and CVolt pins of the NE555 chip are grounded through capacitors respectively, GND pins of the NE555 chip are grounded directly, VCC pins and R pins of the NE555 chip are connected with a power supply, and TRIG pins and Q pins of the NE555 chip are connected with two ends of the sliding rheostat respectively.

Further, the model of the single chip microcomputer is AT89C 52R.

Further, the display circuit is composed of a 6-bit digital tube.

Further, the wireless communication module adopts a radio frequency module consisting of an nRF2401 singlechip radio frequency transceiver chip.

Further, the FPGA control circuit comprises a control chip, and the model of the control chip is EP4CE10F17C 8N.

Further, the amplifying circuit adopts a 9013 series triode.

Further, the switch selection circuit comprises a single-open double-control switch, and a pin 1 and a pin 3 of the single-open double-control switch are respectively connected with the external signal to be detected and a pin Q of an NE555 chip in the NE555 square wave generation circuit.

Further, the shaping circuit comprises shaping circuits corresponding to three frequency band parts, the three frequency bands comprise a 5ns frequency band, a 40ns frequency band and a 100ns frequency band, the shaping circuit corresponding to the 5ns frequency band is composed of a comparator LM311, the shaping circuit corresponding to the 40ns frequency band is composed of a comparator MAX908, and the shaping circuit corresponding to the 100ns frequency band is composed of a comparator MAX 9010.

Compared with the prior art, the utility model has the advantages of it is following:

(1) and various frequency measurement modes are realized. In order to solve the frequency measurement work in outdoor or small teaching scenes, the invention realizes two frequency measurement modes through a switch selection circuit. Namely an external frequency measurement and an internal frequency measurement. The first mode is: when the external measurement function is selected, an external signal enters a frequency meter, is amplified by an amplifying circuit, is shaped by a frequency division shaping circuit, and then enters an FPGA frequency measurement module and the like. The mode is suitable for any external measurement scene, and errors generated in frequency measurement are reduced through frequency division shaping. The second mode is: and (4) a self-test mode. The square wave signal is generated by an on-board NE555 square wave generating circuit, and the generated frequency can be adjusted by a user. And man-machine interaction is realized. The generated signals are amplified by the amplifying circuit and finally sent to the FPGA module for frequency measurement and the like, and the function is suitable for application of small teaching scenes and the like.

(2) The error is small. And frequency division shaping is adopted, so that the measurement precision is improved, and the measurement error is reduced. The frequency division circuit adopts a comparator LM311 to carry out low-frequency shaping; comparator MAX908 performs intermediate frequency shaping; carrying out high-frequency shaping on the comparator MAX 9010; by frequency division shaping the measured external signal, the error generated by frequency measurement can be reduced too much.

(3) The storage capacity is large. The wireless communication module is used for transmitting frequency measurement data to terminal equipment such as a computer and a mobile phone, and is convenient for further analysis, mass storage and the like. The workload of manual recording and errors caused by the manual recording are reduced, and the method is suitable for large data storage, analysis and the like.

(4) And operating the speed block. The frequency meter combining the FPGA and the single chip microcomputer is adopted to realize a better and faster frequency measurement function, and the single chip microcomputer ATC89C52R provides a processing function for FPGA frequency measurement data and realizes a convenient human-computer interaction function.

Drawings

To further clarify the above and other advantages and features of various embodiments of the present invention, a more particular description of various embodiments of the invention will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. Also, the relative positions and sizes of the respective portions shown in the drawings are exemplary, and should not be understood as uniquely determining positional or dimensional relationships between the respective portions.

FIG. 1 is a schematic block diagram of the overall circuit of the present invention;

fig. 2 is a partial circuit diagram of the embodiment of the present invention, which is composed of a switch selection circuit, an external detection signal, an NE555 square wave generation circuit, and an amplification circuit;

fig. 3 is a shaping circuit diagram according to an embodiment of the present invention, in which fig. 3(a) is a low frequency part shaping circuit diagram, fig. 3(b) is an intermediate frequency part shaping circuit diagram, and fig. 3(c) is a high frequency part shaping circuit diagram;

fig. 4 is a schematic block diagram of a wireless transmission module according to an embodiment of the present invention;

in the figure, 1 is a switch selection circuit; 2 is an external measured signal; an NE555 square wave generating circuit is adopted as the circuit 3; 4 is an amplifying circuit; 5 is a shaping circuit; 6 is an FPGA control circuit; 7 is a display circuit; and 8, a wireless communication module.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall fall within the protection scope of the present invention.

Examples

As shown in fig. 1, the utility model discloses the whole circuit schematic block diagram that technical scheme corresponds embodiment, including switch selection circuit 1, the outside surveyed signal 2, NE555 square wave generating circuit 3, amplifier circuit 4, shaping circuit 5, FPGA control circuit 6, display circuit 7 and wireless communication module 8, when switch selection circuit 1 selected outside measuring signal, measuring signal is connected with amplifier circuit 4's input, the signal after the amplification gets into shaping circuit 5 from amplifier circuit 4 output and carries out the frequency division shaping, square wave signal after the shaping gets into FPGA control circuit 6 from shaping circuit 5's output and carries out precision frequency measurement such as, frequency information after the frequency measurement carries out data processing and man-machine interaction function through singlechip ATC89C52R, and show the measuring result through singlechip and display circuit 7, carry out wireless transmission etc. with wireless communication module 8. The FPGA control circuit 6 measures frequency by adopting an equal-precision measurement method, the shaping circuit 5 measures frequency division, and signals in internal measurement are generated by the NE555 square wave generating circuit 3.

The NE555 square wave generating circuit 3, the amplifying circuit 4, the shaping circuit 5, the FPGA control circuit 6, the display circuit 7 and the wireless communication module 8 are independent modules and do not interfere with each other.

As shown in fig. 2: the switch selection circuit 1 is specifically selected to be a single-open double-control switch, a pin port 2 of the switch selection circuit is connected with the input end of the amplifying circuit 4, a pin port 3 of the switch selection circuit is connected with a pin Q of an NE555 chip in the NE555 square wave generating circuit 3, and a pin port 1 of the switch selection circuit is used for measuring external signals.

The NE555 square wave generating circuit 3 in the figure 2 is composed of an NE555 chip, the GND end of the NE555 chip is grounded, the VCC end and the R end are connected with a power supply, the THR and CVolt ports are respectively connected with a capacitor and are grounded in parallel, the TRIG end and the THR end are connected with a sliding 10K sliding rheostat in parallel, and the other end of the sliding rheostat is connected with a No. 3 pin port of a single-switch double-control switch.

As shown in fig. 2: the emitter of the amplifying circuit 4 is used for connecting the FPGA module and the second pole of the square wave generating circuit, and the amplifying circuit connected with the NE555 square wave generating circuit 3 is composed of a 9013 triode.

The amplified signals are divided into low-frequency, intermediate-frequency and high-frequency signals by a selector, and then enter corresponding shaping circuits for shaping.

As shown in fig. 3(a), 3(b) and 3 (c): in the low-frequency shaping circuit, a comparator LM311 is taken as the main part, a signal voltage to be amplified enters from the 3 end of the comparator LM311 through a resistor R1 and two diodes D1 and D2 which are connected in parallel, the signal voltage is output from the 7 end through a resistor R2, and a port 2 of the comparator is connected with a port 6 and is connected with the two diodes in parallel; in the intermediate frequency shaping circuit, the amplified voltage of an external measurement sine wave signal enters from a port 3 of a MAX908 comparator and is output through a port 7, a port 2 of the MAX908 is connected with a resistor R3 and is grounded, one end of the R3, which is connected with the port 2, is connected with a port R1 in parallel, and the output end of the R1 is connected with the output end of the MAX 908; in the high-frequency shaping circuit, amplified voltage enters from a port 2 of a comparator MAX9010 and is shaped and output from a port 7 of the comparator MAX9010, wherein a voltage input interface is connected with a resistor R1, a resistor R2 is connected with a resistor R4 in series, a resistor R3 is connected with a resistor R5 in series, and then two groups of series circuits are connected in parallel with each other and are connected with a port 3 and a port 4 of the comparator MAX 9010.

The FPGA control circuit adopts an equal-precision measurement method to measure frequency, and the principle is as follows: the precision Gate, i.e. the synchronous Gate, is controlled by the signal Fx to be measured and the preset Gate _ p. When the rising edge of the first Fx in the preset door comes, the Gate of the precise door is opened, at the moment of the rising edge of the first Fx after the preset door is finished, the Gate is closed, in the precise door, the count values of the signal to be measured Fx and the high-frequency standard pulse Fo are respectively NA and NB, and the measured frequency is

As shown in fig. 4: the information after FPGA frequency measurement is processed by an ATC89C52R core and is wirelessly transmitted to terminal equipment through a radio frequency module nRF2401, and the principle is as follows: the single chip microcomputer AT89C52R writes in a control command and frequency information measured by the FPGA circuit of the frequency measurement module through an IO bus nRF2401, and the nRF2401 sends data to a terminal receiving device through an antenna.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope of the present invention, and these modifications or replacements should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A digital frequency meter with a dual-mode wireless transmission function is characterized by comprising a switch selection circuit (1), an external signal to be measured (2), an NE555 square wave generation circuit (3), an amplification circuit (4), a shaping circuit (5), an FPGA control circuit (6), a display circuit (7) and a wireless communication module (8), wherein the switch selection circuit (1) can be connected with the FPGA control circuit (6) through a signal transmission path I or a signal transmission path II, measures frequency and then is connected with the display circuit (7) for displaying a measurement result and the wireless communication module (8) for wirelessly transmitting data through a single chip microcomputer;

the first signal transmission path comprises the external signal to be tested (2), the amplifying circuit (4) and the shaping circuit (5) which are sequentially connected, and the first signal transmission path is correspondingly connected with the switch selection circuit (1) and the FPGA control circuit (6) through the external signal to be tested (2) and the shaping circuit (5);

the second signal transmission path comprises the NE555 square wave generating circuit (3) and the amplifying circuit (4) which are sequentially connected, and the second signal transmission path is correspondingly connected with the switch selection circuit (1) and the FPGA control circuit (6) through the NE555 square wave generating circuit (3) and the amplifying circuit (4).

2. The digital frequency meter with the dual-mode wireless transmission function as claimed in claim 1, wherein the NE555 square wave generating circuit (3) comprises an NE555 chip, THR and CVolt pins of the NE555 chip are grounded through capacitors respectively, a GND pin of the NE555 chip is grounded directly, a VCC pin and an R pin of the NE555 chip are connected with a power supply respectively, and a TRIG pin and a Q pin of the NE555 chip are connected with two ends of a sliding rheostat respectively.

3. The digital frequency meter with the dual-mode wireless transmission function as claimed in claim 1, wherein the single chip microcomputer is AT89C 52R.

4. A digital frequency meter with dual mode wireless transmission function according to claim 1, characterized in that the display circuit (7) is composed of a 6-bit digital tube.

5. A digital frequency meter with dual-mode wireless transmission function according to claim 1, wherein the wireless communication module (8) is a radio frequency module consisting of nRF2401 single-chip microcomputer radio frequency transceiver chip.

6. A digital frequency meter with dual-mode wireless transmission function according to claim 1, characterized in that the FPGA control circuit (6) comprises a control chip, the control chip being of the type EP4CE10F17C 8N.

7. A digital frequency meter with dual-mode wireless transmission function according to claim 1, characterized in that the amplifying circuit (4) adopts a 9013 series triode.

8. A digital frequency meter with dual-mode wireless transmission function according to claim 1, wherein the switch selection circuit (1) comprises a single-open double-control switch, and pin 1 and pin 3 of the single-open double-control switch are respectively connected with the external signal to be measured (2) and the Q pin of the NE555 chip in the NE555 square wave generation circuit (3).

9. The digital frequency meter with the dual-mode wireless transmission function according to claim 1, wherein the shaping circuit (5) comprises shaping circuits corresponding to three frequency band portions, the three frequency bands comprise a 5ns frequency band, a 40ns frequency band and a 100ns frequency band, the shaping circuit corresponding to the 5ns frequency band is composed of a comparator LM311, the shaping circuit corresponding to the 40ns frequency band is composed of a comparator MAX908, and the shaping circuit corresponding to the 100ns frequency band is composed of a comparator MAX 9010.