Input protection circuit of vehicle-mounted reversing video and detection method

Abstract

An input protection circuit of a vehicle-mounted reversing video comprises a relay, a switch tube, an MCU and a reversing signal detection module. A movable contact of the relay is connected with theCVBS signal input end and a first pole of the switch tube respectively; a second AD pin of the MCU is connected with a first static contact of the relay through a second resistor and a ninth resistorso as to acquire voltage V4 of a connection point of the second resistor and the ninth resistor; a second static contact of the relay is grounded through a ground matching resistor at the video inputend of the display screen; the control end of the relay is connected with the first GPIO pin of the MCU; the first AD pin of the MCU is connected with the second pole of the switching tube to acquirethe output voltage V2 of the second pole; a second GPIO pin of the MCU is connected with a reversing signal input end through a reversing signal detection module so as to detect a reversing signal; and the MCU controls the output of the control end of the relay according to whether the reversing signal, the voltage V2 and the voltage V4 are detected or not. According to the invention, the protection control of the CVBS signal input end can be realized, and the normal display and abnormal reminding of the reversing video can be ensured.

Description

technical field [0001] The invention relates to the technical field of vehicle-mounted multimedia display screens, in particular to an input protection circuit and method for vehicle-mounted reversing video. Background technique [0002] With the rapid development of the automobile market, the application of vehicle multimedia display screens on trucks is becoming more and more extensive. With the requirements for driving safety, the reversing video function has become a standard function on the multimedia display, because the reversing video brings great convenience to the driver during the reversing process, and can observe the rear situation at any time, thus providing the safety of car driving . However, when the car leaves the factory, due to the consideration of its cost or other reasons, the reversing camera in the multimedia display screen is not equipped as standard. When customers want this function, they can only go to the corresponding maintenance center or 4S s...

AI Technical Summary

Problems solved by technology

However, when the car leaves the factory, due to the consideration of its cost or other reasons, the reversing camera in the multimedia display screen is not equipped as standard. When customers want this function, they can only go to the corresponding maintenance center or 4S shop for modification. At this time Due to the individuality of the customer's choice of the reversing camera, the interface of the camera may also be mismatched. If the definition of the interface between the display screen and the camera is not understood, the pins of the CVBS signal and the 12V power supply are connected in reverse ( That is, connect the 12V power supply to the reversing video input terminal of the display screen), connect the reversing camera, enter the reversing video preview, and the reversing video cannot be displayed normally on the display screen

Because the 12V power supply is connected to the reversing video input terminal of the display screen, the 75 ohm resistor to the ground of the reversing video input terminal burns out and is short-circuited to the ground, thus causing the reversing video input terminal of the display screen to be short-circuited to the ground, and the reversing video on the display screen is short-circuited. The video function does not work

In order to avoid similar problems, the general method is to choose a high-power resistor for the ground-matching resistance of the video input terminal of the display screen at 75 ohms or add a self-recovery fuse at the front end of the video input. These measures have disadvantages and cannot be reminded in real time to install Abnormal status of people reversing video

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