Method and circuit for realizing LCD TV VGA arousing function

Abstract

A method for realzing VGA arousing function of liquid crystal television and a circuit thereof, wherein the method comprises: according to characteristics of VGA terminal nine-pin voltage changing from low to high when a VGA is output, adopting an external circuit, generating a low electric level pulse with adjustable pulse width at will, a main chip I / O can arouse VGA of a liquid crystal television and a display through detecting the low electric level pulse; the circuit comprises XS1 which is used as a VGA interface, one I / O interface which uses Detect as the main IC, using VCC as a power source; when a VGA signal is output, 9 pin A point electric level nine-pin A point electrical level of the VGA termial is changed from low (0V) to high (5V), a low electric level pulse is formed through the circuit B point, once the low electric level pulse is detected by the I / O interface Detect, the VGA function of the system is aroused. The detecting pin Detect does not occupy a new I / O interface of the main chip through multiplexed key input port key; the method does not need the main chip reading registers and detecting VGA line-field synchronously, does not need ADC power supply, which uses characteristics of VGA terminal nine-pin voltage changing from low to high when a VGA is output to realize VGA arousing function of liquid crystal televisions and display products.

Description

Technical field [0001] The invention relates to a wake-up method of a liquid crystal television, in particular to a method for realizing a VGA wake-up function when a liquid crystal display device is used as a display, and a VGA wake-up circuit. Background technique [0002] The VGA wake-up function of existing LCD TVs and display products is often implemented in the following ways: As shown in Figure 1, ADC POWER is the main chip's ADC power supply, register 1 accesses the VGA's line synchronization signal (VGA_HSYNC), and register 2. Access the vertical sync signal (VGA_VSYNC) of the VGA. When the system is in standby, the main chip MCU reads the line and field register status in each main cycle program cycle and judges the line and field synchronization signal through a complex software algorithm. Once the VGA line and field synchronization signal is detected, it immediately wakes up the VGA function of the display. Since the existing VGA wake-up function is implemented in the...

AI Technical Summary

Problems solved by technology

Since the existing VGA wake-up function is realized when the main chip MCU continuously detects the line and field synchronization of the VGA signal in the system standby state, this requires that the ADC power supply of the chip cannot be powered off when the display is in standby, which increases the standby function of the system. While the program is running, it continuously accesses the row-field synchronization registers, causing the main chip MCU to fail to enter the low-power consumption state of standby and dormancy, which consumes a certain amount of system resources.

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