CN111308391A - An automobile wiring harness continuity detection circuit - Google Patents

Abstract

The invention discloses an automobile wiring harness continuity detection circuit, which comprises a unit board, a main board, an on-off detection circuit, a voltage comparison circuit, a voltage detection circuit and a power supply circuit. The unit board and the main board are respectively connected to a JTAP circuit, an RS485 circuit, a reset circuit, The MCU decoupling circuit, the crystal oscillator circuit, and the power supply circuit are respectively electrically connected to the main board and the unit board. The detection logic of the invention is simple and the versatility is strong. The continuity detection circuit has a total of 64 circuits, and an external expandable module can be applied to various types and quantities. harness inspection.

Description

An automobile wiring harness continuity detection circuit

technical field

The invention relates to the technical field of wire harness continuity detection, in particular to an automobile wire harness continuity detection circuit.

Background technique

With the rapid development of science and technology, electronic devices are almost everywhere, and the wiring harness is like the nerve veins of the human body, transmitting complex signals and instructions to various parts. The safety and reliability of the wiring harness is very important. How to locate, diagnose and trace the fault of the wiring harness has always been a concern of the wiring harness inspection industry.

The traditional electrical detection method of automobile wiring harness uses tools such as indicator lights, multimeters and buzzers to judge the on-off of automobile wiring harness by observing whether there are electrical, sound and light signals by means of point-by-point overlap. This detection method is slow and manual. The detection efficiency is low, the operator is easily fatigued, the intelligence level is low, the quality of the inspection personnel is high, and it is easy to cause wrong inspection and missed inspection of the wiring harness, and the inspection results are difficult to analyze statistically.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an automobile wiring harness continuity detection circuit to solve the problems raised in the above background art.

In order to achieve the above purpose, the present invention provides the following technical solutions: an automobile wiring harness continuity detection circuit, comprising a unit board, a main board, an on-off detection circuit, a voltage comparison circuit, a voltage detection circuit, and a power supply circuit, wherein the unit board and the main board are respectively Connect the JTAP circuit, the RS485 circuit, the reset circuit, the MCU decoupling circuit, and the crystal oscillator circuit. The power supply circuit is electrically connected to the main board and the unit board respectively, the main board is connected to the serial port circuit, and the unit board and the main board model are STM32.

Preferably, the unit board is connected to the on-off detection circuit through the 74HC595 circuit, the on-off detection circuit is connected to the unit board through the 74HC165 circuit, the unit board is bidirectionally connected to the voltage comparison circuit, and the voltage comparison circuit is bidirectionally connected to the voltage detection circuit, The voltage detection circuit is bidirectionally connected to a multi-channel analog switch circuit, and the multi-channel analog switch circuit is connected to an on-off detection circuit.

Preferably, the continuity detection circuit is mainly composed of a serial port to parallel port circuit, a parallel port to serial port circuit and a voltage detection circuit, the serial port to parallel port circuit includes 8 cascaded HC595 chips, and the parallel port to serial port circuit includes 8 Cascaded HC156 chips, the voltage detection circuit is composed of 64 MOS tubes.

Preferably, the voltage detection circuit includes a first digital-to-analog converter, a second digital-to-analog converter, a first dual voltage comparator and a second dual voltage comparator, and the output end of the first digital-to-analog converter is connected to One end of the resistor A, the other end of the resistor A is respectively connected to one end of the resistor B, one end of the capacitor A and the positive input end of the first dual voltage comparator, the other end of the resistor B is connected to the other end of the capacitor A and grounded, the first dual voltage The output end of the comparator is connected to one end of the resistor C and outputs a high level, the negative input end of the first two-way voltage comparator receives the voltage end to be measured; the output end of the second digital-to-analog converter is connected to one end of the resistor D, and the other end of the resistor D Connect one end of the resistor E, one end of the capacitor B and the positive input end of the second dual voltage comparator respectively, the other end of the resistor E is connected to the other end of the capacitor B and grounded, and the output end of the second dual voltage comparator is connected to one end of the resistor F and outputs a low level, and the negative input terminal of the second dual voltage comparator receives the voltage terminal under test.

Preferably, its detection method comprises the following steps:

A. STM32 in the main board sends the "calling" command to the unit board;

B. The unit board controls the 74HC595 serial port/parallel port circuit to apply different detection signals to the on-off detection circuit, and returns the test results to the unit board through the 74HC165 parallel port/serial port circuit, and then the unit board "responds" to the main board, realizing closed-loop control ;

C. The channel circuits in the multi-channel analog switch circuit have resistors with different resistance values, thereby realizing the resistance measurement of various voltage measurement ranges.

Preferably, the conduction detection circuit detection method is as follows:

A. STM32 parses the command of the host computer, applies the high and low levels to the gate of the MOS tube through the HC595 chip, and the detected wiring harness is connected to the output point OUT;

B. The HC165 chip feeds back the high and low points of the detection point OUT to the STM32, and then completes the collection of the detection voltage of the wiring harness;

C. CTRH0, CTRH1...CTRH63 controls the high end of the MOS tube 203, CTRL0, CTRL1...CTRL63 controls the low end of the MOS tube, OUT0, OUT1...OUT63 is the level detection point, so a unit board can detect 64 point;

D. If the two ends of a detected harness are connected to OUT0 and OUT63, the high-end drive input of the MOS tube of OUT0 during detection is high, and the high-end drive input of the MOS tubes of other output points is low. The low-end drive of 203 always inputs a low level;

E. OUT0 outputs high voltage. If the wiring harness is turned on, OUT63 outputs high voltage. If the wiring harness is faulty, it outputs low voltage.

Preferably, the voltage comparison method is as follows:

A. Use a dual voltage comparator to compare the two input voltages, and then output the logic level;

B. The analog voltage output by the digital-to-analog converter is the reference voltage of LM319, and the voltage to be measured is connected to the "-" input terminal of LM319;

C. Since LM319 is OC output, connect pull-up resistor to ensure high-level output;

D. This voltage comparison circuit mainly logically compares the voltage output by the continuity detection circuit with the set reference voltage, and then converts the voltage into a logic level and uploads it to the host computer system for data calculation and storage, so the wiring harness is turned on. detection.

Compared with the prior art, the present invention has the following beneficial effects: the present invention has simple detection logic, strong versatility, a total of 64 conduction detection circuits, an external expandable module, and is applicable to various types and quantities of wire harness detection.

Description of drawings

Fig. 1 is the control principle block diagram of the present invention;

2 is a schematic diagram of a conduction detection circuit of the present invention;

FIG. 3 is a schematic diagram of a voltage comparison circuit of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

1-3, the present invention provides a technical solution: an automobile wiring harness continuity detection circuit, including a unit board 1, a main board 2, a continuity detection circuit 3, a voltage comparison circuit 4, a voltage detection circuit 5, and a power supply circuit 6. The unit board 1 and the main board 2 are respectively connected to the JTAP circuit 7, the RS485 circuit 8, the reset circuit 9, the MCU decoupling circuit 10, and the crystal oscillator circuit 11, and the power circuit 6 is electrically connected to the main board 2 and the unit board 1, respectively, The main board 2 is connected to the serial port circuit 12, and the model of the unit board 1 and the main board 2 adopts STM32; , the unit board 1 is bidirectionally connected to the voltage comparison circuit 4, the voltage comparison circuit 4 is bidirectionally connected to the voltage detection circuit 5, the voltage detection circuit 5 is bidirectionally connected to the multi-channel analog switch circuit 15, and the multi-channel analog switch circuit 15 is connected to On-off detection circuit 3.

In the present invention, the continuity detection circuit is mainly composed of a serial port to parallel port circuit, a parallel port to serial port circuit and a voltage detection circuit. The serial port to parallel port circuit includes 8 cascaded HC595 chips 201, and the parallel port to serial port circuit includes 8 For the cascaded HC156 chips 202 , the voltage detection circuit is composed of 64 MOS transistors 203 .

In the present invention, the voltage detection circuit includes a first digital-to-analog converter 16, a second digital-to-analog converter 17, a first dual voltage comparator 18 and a second dual voltage comparator 19. The first digital-to-analog converter 16 The output end is connected to one end of the resistor A1a, the other end of the resistor A1a is respectively connected to one end of the resistor B2a, one end of the capacitor A1b and the positive input end of the first dual voltage comparator 20, the other end of the resistor B2a is connected to the other end of the capacitor A1b and grounded, the The output end of the first two-way voltage comparator 20 is connected to one end of the resistor C3a and outputs a high level, the negative input end of the first two-way voltage comparator 18 receives the voltage under test; the output end of the second digital-to-analog converter 17 is connected to One end of the resistor D4a, the other end of the resistor D4a is respectively connected to one end of the resistor E5a, one end of the capacitor B2b and the positive input end of the second dual-channel voltage comparator 19, the other end of the resistor E5a is connected to the other end of the capacitor B2b and grounded, the second dual-channel voltage comparator 19. The output end of the voltage comparator 19 is connected to one end of the resistor F6a and outputs a low level, and the negative input end of the second dual-circuit voltage comparator 19 is the voltage end under test.

The detection method of the present invention comprises the following steps:

A. STM32 in the main board sends the "calling" command to the unit board;

B. The unit board controls the 74HC595 serial port/parallel port circuit to apply different detection signals to the on-off detection circuit, and returns the test results to the unit board through the 74HC165 parallel port/serial port circuit, and then the unit board "responds" to the main board, realizing closed-loop control ;

C. The channel circuits in the multi-channel analog switch circuit have resistors with different resistance values, thereby realizing the resistance measurement of various voltage measurement ranges.

In addition, in the present invention, the conduction detection circuit detection method is as follows:

A. STM32 parses the command of the host computer, applies the high and low levels to the gate of the MOS tube through the HC595 chip, and the detected wiring harness is connected to the output point OUT;

B. The HC165 chip feeds back the high and low points of the detection point OUT to the STM32, and then completes the collection of the detection voltage of the wiring harness;

C. CTRH0, CTRH1...CTRH63 controls the high end of the MOS tube 203, CTRL0, CTRL1...CTRL63 controls the low end of the MOS tube, OUT0, OUT1...OUT63 is the level detection point, so a unit board can detect 64 point;

D. If the two ends of a detected harness are connected to OUT0 and OUT63, the high-end drive input of the MOS tube of OUT0 during detection is high, and the high-end drive input of the MOS tubes of other output points is low. The low-end drive of 203 always inputs a low level;

E. OUT0 outputs high voltage. If the wiring harness is turned on, OUT63 outputs high voltage. If the wiring harness is faulty, it outputs low voltage.

In the present invention, the voltage comparison method is as follows:

A. Use a dual voltage comparator to compare the two input voltages, and then output the logic level;

B. The analog voltage output by the digital-to-analog converter is the reference voltage of LM319, and the voltage to be measured is connected to the "-" input terminal of LM319;

C. Since LM319 is OC output, connect pull-up resistor to ensure high-level output;

D. This voltage comparison circuit mainly compares the voltage output by the continuity detection circuit with the set reference voltage, and then converts the voltage into a logic level and uploads it to the host computer system for data calculation and storage, so the wiring harness is turned on. detection.

To sum up, the detection logic of the present invention is simple, and the versatility is strong. There are 64 conduction detection circuits in total, and an external expandable module can be used to detect various types and quantities of wire harnesses.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes within the meaning and scope of the equivalents of , are included in the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

Claims (7)

1. The utility model provides an automobile wire harness conduction detection circuit, includes cell board (1), mainboard (2), break-make detection circuit (3), voltage comparison circuit (4), voltage detection circuit (5), power supply circuit (6), its characterized in that: JTAP circuit (7), RS485 circuit (8), reset circuit (9), MCU decoupling circuit (10), crystal oscillator circuit (11) are connected respectively to cell board (1) and mainboard (2), power supply circuit (6) electric connection mainboard (2) and cell board (1) respectively, serial circuits (12) are connected in mainboard (2), STM32 is adopted to cell board (1) and mainboard (2) model.

2. The automotive wiring harness conduction detection circuit according to claim 1, characterized in that: the unit board (1) is connected with the on-off detection circuit (3) through a 74HC595 circuit (13), the on-off detection circuit (3) is connected with the unit board (1) through a 74HC165 circuit (14), the unit board (1) is connected with the voltage comparison circuit (4) in two directions, the voltage comparison circuit (4) is connected with the voltage detection circuit (5) in two directions, the voltage detection circuit (5) is connected with the multi-path analog switch circuit (15) in two directions, and the multi-path analog switch circuit (15) is connected with the on-off detection circuit (3).

3. The automotive wiring harness conduction detection circuit according to claim 1, characterized in that: the conduction detection circuit mainly comprises a serial port-to-parallel port circuit, a parallel port-to-serial port circuit and a voltage detection circuit, the serial port-to-parallel port circuit comprises 8 cascaded HC595 chips (201), the parallel port-to-serial port circuit comprises 8 cascaded HC156 chips (202), and the voltage detection circuit comprises 64 MOS (metal oxide semiconductor) tubes (203).

4. The automotive wiring harness conduction detection circuit according to claim 1, characterized in that: the voltage detection circuit comprises a first digital-to-analog converter (16), a second digital-to-analog converter (17), a first double-circuit voltage comparator (18) and a second double-circuit voltage comparator (19), wherein the output end of the first digital-to-analog converter (16) is connected with one end of a resistor A (1a), the other end of the resistor A (1a) is respectively connected with one end of a resistor B (2a), one end of a capacitor A (1B) and the positive electrode input end of the first double-circuit voltage comparator (20), the other end of the resistor B (2a) is connected with the other end of the capacitor A (1B) and is grounded, the output end of the first double-circuit voltage comparator (20) is connected with one end of a resistor C (3a) and outputs high level, and the negative electrode input end of the first double-circuit voltage comparator (; the output end of the second digital-to-analog converter (17) is connected with one end of a resistor D (4a), the other end of the resistor D (4a) is respectively connected with one end of a resistor E (5a), one end of a capacitor B (2B) and the positive input end of a second double-circuit voltage comparator (19), the other end of the resistor E (5a) is connected with the other end of the capacitor B (2B) and is grounded, the output end of the second double-circuit voltage comparator (19) is connected with one end of a resistor F (6a) and outputs low level, and the negative input end of the second double-circuit voltage comparator (19) is connected with a voltage end to be tested.

5. The detection method for realizing the automobile wire harness conduction detection circuit of claim 1 is characterized in that: the detection method comprises the following steps:

A. the STM32 in the mainboard sends a 'roll call' instruction to the cell board;

B. the unit board controls the 74HC595 serial port/parallel port circuit to apply different detection signals to the on-off detection circuit, and the detection result is returned to the unit board through the 74HC165 serial port/serial port circuit, so that the unit board responds to the mainboard, and closed-loop control is realized;

C. the channel circuits in the multi-channel analog switch circuit are all provided with resistors with different resistance values, so that the resistor measurement in various voltage measurement ranges is realized.

6. The automotive wiring harness conduction detection circuit according to claim 3, characterized in that: the detection method of the conduction detection circuit comprises the following steps:

A. the STM32 analyzes the upper computer command, applies high and low levels to the grid of the MOS tube through the HC595 chip, and the detected wire harness is connected to an output point OUT;

B. the HC165 chip feeds back the high and low points of the detection point OUT to the STM32 so as to finish the acquisition of the detection voltage of the wiring harness;

C. the CTRH0 and the CTRH1 … … CTRH63 carry OUT high-end control on the MOS tube 203, the CTRL0 and the CTRL1 … … CTRL63 carry OUT low-end control on the MOS tube, and the OUT0 and the OUT1 … … OUT63 are level detection points, so that 64 points can be detected by one cell board;

D. if two ends of a detected wire harness are connected with two points of OUT0 and OUT63, therefore, high level is input to the high-end drive of the MOS tube of OUT0 during detection, low level is input to the high-end drive of the MOS tubes of other output points, and low level is always input to the low-end drive of the MOS tube 203;

E. OUT0 outputs a high voltage, OUT63 outputs a high voltage if the harness is on, and outputs a low voltage if the harness fails.

7. The automotive wiring harness conduction detection circuit according to claim 4, characterized in that: the voltage comparison method comprises the following steps:

A. comparing the two input voltages by using a two-way voltage comparator, and further outputting a logic level;

B. the analog voltage output by the digital-to-analog converter is the reference voltage of the LM319, and the voltage to be measured is connected with the < - > input end of the LM 319;

C. since LM319 is OC output, so connect pull-up resistance and guarantee the high level to export;

D. the voltage comparison circuit is mainly used for logically comparing the voltage output by the conduction detection circuit with the set reference voltage, and further converting the voltage into a logic level and uploading the logic level to an upper computer system for data operation and storage, so that the detection of the conduction of the wiring harness is realized.

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