CN2615672Y

CN2615672Y - Hand-held graphic digital universal meter

Info

Publication number: CN2615672Y
Application number: CN 03225300
Authority: CN
Inventors: 张文
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-04-15
Filing date: 2003-04-15
Publication date: 2004-05-12
Anticipated expiration: 2013-04-15

Abstract

A portable digital multimeter with graphic representation comprises a single chip microcomputer, a testing circuit for analog variable connecting the corresponding port of the single chip microcomputer, a logic testing circuit, a LCD display module, a micro keyboard with multifunction, a RS232 connecting circuit, a buzzer, function or quantum selecting switches, testing holes and a power, wherein the testing circuit for analog variable and the logic testing circuit could be electrically connected with the testing holes respectively by the function or quantum selecting switches. The portable digital multimeter with graphic representation employs the single chip microcomputer with high quality to finish data sampling, transforming, processing and process control, thereby simplifying the conformation of hardware, reducing cost, improving reliability at the same time, and with the support of powerful software, the voltage wave and voltage-current characteristic could be displayed on the digital multimeter and could be used for testing on line, logic analysis and test without electricity, and furthermore, the digital has the functions of storage and communication.

Description

Hand-held diagram digital multimeter

Technical field

The utility model relates to the general electronic corporation proving installation, specifically is a kind of hand-held diagram digital multimeter of testing electric weight, circuit parameter, logic state and sequence.

Background technology

At present, the most frequently used hand-held electric appliance proving installation of people is a digimer, common digimer is made up of function/range switch, range conversion network, input amplifier, A/D transducer, display, be mainly used to measuring voltage, electric current and resistance, what have has added test functions such as transistor enlargement factor, electric capacity, frequency, temperature, and its weak point is: 1. can not display waveform and curve; 2. only be suitable for the test of analog quantity, be unsuitable for the test of Digital Logic, especially logic sequence.Though, some import digimers energy display waveform and curves are arranged, it costs an arm and a leg, and inconvenience is promoted the use of.

Summary of the invention

The purpose of this utility model be to provide a kind of have the common test function and can display voltage waveform and E-I characteristic, be suitable for the hand-held diagram digital multimeter of the cheapness of logic analysis test.

The hand-held diagram of the utility model digital multimeter, comprise single-chip microcomputer, be connected analog quantity test circuit, logic test circuit, LCD display module, multifunction micro keyboard, RS232 interface circuit and the hummer of single-chip microcomputer corresponding port, function/range switch, test jack and power supply, analog quantity test circuit and logic test circuit are electrically connected with test jack by function/range switch respectively.

This hand-held diagram digital multimeter adopts the high-performance single-chip microcomputer to gather conversion, data processing and process control, has simplified hardware configuration, has reduced cost, has improved reliability simultaneously; Under the support of powerful software function, make this digital multimeter energy display voltage waveform and E-I characteristic, and can be used for not powering up on-line testing and logic analysis test; In addition, this digital multimeter also possesses storage and communication function.

Description of drawings

Fig. 1 is the theory diagram of this hand-held diagram digital multimeter;

Fig. 2 is the analog quantity test circuit schematic diagram of its exemplary embodiments;

Fig. 3 is the logic test circuit schematic diagram of its exemplary embodiments.

Embodiment

Be described further below in conjunction with accompanying drawing.

Hand-held diagram digital multimeter shown in Figure 1 comprises single-chip microcomputer, be connected analog quantity test circuit, logic test circuit, LCD display module, multifunction micro keyboard, RS232 interface circuit and the hummer of single-chip microcomputer corresponding port, function/range switch, test jack and power supply, analog quantity test circuit and logic test circuit are electrically connected with test jack by function/range switch respectively.Described analog quantity test circuit contains penultimate amplifier 1, penultimate amplifier 2, measuring amplifier 1, measuring amplifier 2, constant current source and range conversion network, the range conversion network is electrically connected with the output terminal of penultimate amplifier 1 and penultimate amplifier 2 respectively, the input end of the output termination constant current source of penultimate amplifier 2, the input end of the output termination measuring amplifier 2 of constant current source.Described logic test circuit contains logic state testing circuit, logic sequence input circuit and frequency counting circuit.The DC/DC translation circuit that described power supply contains rechargeable battery and is connected its positive and negative electrode.

With reference to Fig. 2 and Fig. 3, function/range switch 1 is the multistage multi-position switch of multitool interlock, its stage casing corresponding function, and the corresponding range in position, the corresponding multiple spot of multitool switches simultaneously.In Fig. 2, SC2, SC3 are wherein one section, corresponding transistor testing function, and two cuttves have only been used in five range positions, so SC1 does not occur, belong to five on two cuttves.SN1, SN2, SN3 are node diagram functional section, five on three cuttves; SV1, SV2, SV3 are voltage and oscillography functional section, five on three cuttves; SR1, SR2, SR3 are the resistance functional section, five on three cuttves; SA1, SA2 are the function of current section, one on two cuttves; In Fig. 3, SP1 also is one section, logic probe functional section, one on a cutter; SS1, SS2, SS3 are logic oscillography functional section, one on three cuttves; SF1 is the frequency functionality section, one on a cutter.

The range conversion network contains five parts: (1) is by the excitation range network of current-limiting resistance RC1, RC2, RC3, RC4, RC5, the test of RC6 transistor formed; (2) by the excitation range network of current-limiting resistance RN1, RN2, RN3, RN4, RN5 configuration node diagram function; (3) by divider resistance RV1, RV2, the test of RV3 transistor formed and the shared measurement range network of node diagram function; (4) constitute voltage and the shared reconnaissance range network of resistance by divider resistance RS1, RS2, RS3, RS4, RS5; (5) constitute the current-voltage conversion by sample resistance RS6.

Measuring amplifier 1 is made up of integrated transporting discharging A3B, A7B and resistance R 5, R6, R7, R8, is used to measure the feature of electric current, voltage, transistor characteristic or circuit node.During measurement, function/range switch and range conversion network with the measured signal level translation after, send into measuring amplifier 1, send into the 1st passage ADC1 of Chip Microcomputer A/D transducer after the amplification, under software control, voltage/current numerical value or waveform are presented on the LCD on request, and interchange or direct current will be automatically recognized and be indicated.

Measuring amplifier 2 is made up of integrated transporting discharging A4B, resistance R 9, R10, only is used for the resistance measurement function.During measurement, function/range switch is added in the reference current that constant current source produces on the measured resistance, measuring amplifier 2 will be gathered the voltage on the measured resistance, send into the 2nd passage ADC2 of Chip Microcomputer A/D transducer after the amplification, under software control, single-chip microcomputer is converted into resistance value with it, is presented on the LCD display.

Penultimate amplifier 1 is made up of integrated transporting discharging A1B, resistance R 1, R2, VR1; Penultimate amplifier 2 is made up of integrated transporting discharging A2B, resistance R 3, R4, VR2.When measuring the feature of transistor characteristic or circuit node, by software control, the output of the two-way D/A transducer of single-chip microcomputer is added on two electrodes or circuit node of measured device respectively through two penultimate amplifiers, measuring amplifier 1 will be gathered the response signal of measured device or node, send into the 1st passage ADC1 of Chip Microcomputer A/D transducer after the amplification, single-chip microcomputer is handled it, and by function/measurement range selection and keyboard commands transistor characteristor characteristic curve family or circuit node feature pattern is presented on the LCD.

Constant current source is made up of integrated transporting discharging A5B, field effect transistor Q1, resistance R 11, R12, R13, capacitor C 1, switch S R2, SR3, reference resistance RS1, RS2, RS3, RS4, RS5 etc., required reference voltage is supplied with by penultimate amplifier 2, connect the reference current that different reference resistances can be flowed out different sizes by Q1 with the switch choosing, to adapt to the measurement requirement of different range resistance.

The logic state testing circuit is by four Sheffer stroke gate U1, latch U2, transistor Q2, resistance R 14, R15, potentiometer VR3, VR4, compositions such as capacitor C 2, C3.Resistance R 14, potentiometer VR3, VR4 constitute a voltage divider, it has three dividing potential drop nodes, be respectively: the 1) self-cleaning contact of potentiometer VR3, link to each other with Sheffer stroke gate U1 the 1st pin, 2) self-cleaning contact of potentiometer VR4 links to each other 3 with the base stage of transistor Q2) the PROBE end of potentiometer VR3 and VR4 junction, this is the input superposition point of tested logic level, and its level changes must make the level of aforementioned two dividing potential drop nodes become thereupon.Transistor Q2, resistance R 15, potentiometer VR4 form a phase inverter, and its input is exactly tested logic level, and output then links to each other with Sheffer stroke gate U1 the 9th pin.Capacitor C 2, C3 are speed-up capacitors, are used to improve the response speed to measured signal.U1 connects into two rest-set flip-flops, the set input of two rest-set flip-flops is respectively U1 the 1st pin and the 9th pin, link the self-cleaning contact of potentiometer VR3 and the output terminal of phase inverter as previously mentioned respectively, the RESET input of two rest-set flip-flops is respectively U1 the 5th pin and the 13rd pin, all be connected to the T1 of single-chip microcomputer, the respective input of the output termination latch U2 of two rest-set flip-flops, the output of latch U2 is connected to the data bus of single-chip microcomputer.Two rest-set flip-flops can be respectively by detected high low logic level set and remain to reset before, the T1 of single-chip microcomputer can make it reset during for low level, prepare once new detection, after the set moment, gating U2 reads its VH that deposits and VL, just know that the variation on the probe: VH=1 represents to occur too high level, VL=1 represents to occur low level, the both is that extra pulse appears in 1 expression, the both is 0 expression no change, do not examine qualified logic level yet, single-chip microcomputer periodically reads-and reset operation just can realize the detection of logic state, read signal CS2 from code translator U6.When carrying out the logic state detection, function/range switch is sent tested logical signal into the logic state testing circuit, this circuit exports testing result to single-chip microcomputer, under software control, hummer is indicated logic state with different acoustic, and LCD is also with time dependent point, line graph display logic state.

The logic sequence input circuit is made up of phase inverter U3A, U3B, U3C.When checking logic sequence, function/range switch is sent into single-chip microcomputer with three logic sequence signals through the logic sequence input circuit, and under software control, LCD shows the logic sequence waveform of three passages.

Frequency counting circuit is used for survey frequency or cycle, frequency counting circuit contains shaping circuit U3D, 8 digit counter U4, latch U5, resistance R 16, R17 and capacitor C 4, the output of shaping circuit U3D connects the CLK end of counter U4, eight output terminals of counter U4 connect the respective input of latch U5 respectively, and the output data of latch U5 is delivered to the data bus of single-chip microcomputer.During measurement, function/range switch is sent measured signal into the U4 counting after via the U3D shaping, the counter T2 that its carry signal is sent in the single-chip microcomputer makes continuous position counting, the range gate capture that single-chip microcomputer T0 sends is locked U5 with the instant numeral of U4, simultaneously the instant numeral of its internal counter T2 is locked in the relevant register, single-chip microcomputer is shown in LCD with frequency or the cycle that records under software control.Wherein, the signal that reads of latch U5 is CS1 from code translator U6.

The single-chip microcomputer of this hand-held diagram digital multimeter adopts the high-performance Chip Microcomputer A uC8XX of U.S. ADI company, this single-chip microcomputer includes A/D transducer and D/A transducer, utilize it to gather conversion, data processing and process control, under powerful software effect, simplified peripheral circuit and system architecture, made Cheap multi-functional become possibility.

The LCD display module of this hand-held diagram digital multimeter adopts homemade GM12864, and this is a kind of 128 row of driving circuit, dot matrix figure LCD module of 64 row of carrying.

Multifunction micro keyboard in this hand-held diagram digital multimeter is used for Input Software operational order and data; The RS232 interface circuit be used for and computer such as PC between communication so that with too much other computer of measurement data unloading or fetch.

The test function of this hand-held diagram digital multimeter comprises:

(1), DC voltage 0～625V, five ranges

(2), alternating voltage 0～625V peak value, five ranges

(3), DC current 0～250mA

(4), alternating current 0～250mA peak value

(5), resistance 0～25M Ω, a plurality of ranges

(6), the maximum 20MHz of frequency

(7), the transistor enlargement factor 0～1000

(8), 10 grades of transistor characteristor characteristic curves, maximum current 5/10/15/20mA, four ranges

(9), node diagnostic diagram multirange, multi-frequency: 20Hz～4.8KHz can store contrast

(10), the vertical 0～625V of voltage oscillography, 5 ranges, level 65 μ S/D～50mS/D,

Automatically triggering/single is caught

(11), logic probe CMOS/TTL, 20MHz, sound equipment prompting and diagram

(12), 3 passages of logic oscillography, CMOS/TTL, sampling clock: 5 μ S～50mS,

It is optional with delay to trigger polarity.

Claims

1, a kind of hand-held diagram digital multimeter, it is characterized in that: comprise single-chip microcomputer, be connected analog quantity test circuit, logic test circuit, LCD display module, multifunction micro keyboard, RS232 interface circuit and the hummer of single-chip microcomputer corresponding port, function/range switch, test jack and power supply, described analog quantity test circuit and logic test circuit are electrically connected with test jack by function/range switch respectively.

2, hand-held diagram digital multimeter according to claim 1, it is characterized in that: described logic test circuit contains logic state testing circuit, logic sequence input circuit and frequency counting circuit.

3, hand-held diagram digital multimeter according to claim 2, it is characterized in that: frequency counting circuit contains shaping circuit U3D, 8 digit counter U4, latch U5, resistance R 16, R17 and capacitor C 4, the output of shaping circuit U3D connects the CLK end of counter U4, eight output terminals of counter U4 connect the respective input of latch U5 respectively, and the output of latch U5 is connected to the data bus of single-chip microcomputer.

4, hand-held diagram digital multimeter according to claim 2, it is characterized in that: the logic state testing circuit comprises four Sheffer stroke gate U1, latch U2, transistor Q2, resistance R 14, R15, potentiometer VR3, VR4, speed-up capacitor C2, C3; Resistance R 14, potentiometer VR3, VR4 constitutes a voltage divider, transistor Q2 and collector resistance R15 thereof, potentiometer VR4 forms a phase inverter, the base stage of transistor Q2 connects the self-cleaning contact of potentiometer VR4, U1 connects into two rest-set flip-flops, set input 1 pin of two rest-set flip-flops, 9 pin are linked the self-cleaning contact of potentiometer VR3 and the output terminal of phase inverter respectively, the T1 that the RESET input 5 pin of two rest-set flip-flops and 13 pin all are connected to single-chip microcomputer, the respective input of the output termination latch U2 of two rest-set flip-flops, the output of latch U2 connects the data bus of single-chip microcomputer.

5, hand-held diagram digital multimeter according to claim 1, it is characterized in that: described analog quantity test circuit contains penultimate amplifier 1, penultimate amplifier 2, measuring amplifier 1, measuring amplifier 2, constant current source and range conversion network, the range conversion network is electrically connected with the output terminal of penultimate amplifier 1 and penultimate amplifier 2 respectively, the input end of the output termination constant current source of penultimate amplifier 2, the input end of the output termination measuring amplifier 2 of constant current source.

6, hand-held diagram digital multimeter according to claim 1 is characterized in that: the DC/DC translation circuit that described power supply contains rechargeable battery and is connected its positive and negative electrode.

7, novel hand-held diagram digital multimeter according to claim 1 is characterized in that: the Dot LCD Display Module GM12864 that described LCD display module adopts 128*64 to order.

8, hand-held diagram digital multimeter according to claim 1 is characterized in that: described single-chip microcomputer adopts the high-performance Chip Microcomputer A uC8XX that contains A/D and D/A transducer.