CN107241529A - A kind of TTL video output systems and its method - Google Patents

Abstract

The invention discloses a TTL video output system, the first clock signal, the first clock management module and the image output control module are sequentially connected, and the image output control module outputs an image signal that does not contain a clock, so The second clock signal is connected to the second clock management module, and the second clock management module outputs an image clock. The external PLL chip of the present invention is controlled by the FPGA control system, and the external PLL chip can output two clocks and send them to the FPGA. These two clocks are of the same frequency, but have different purposes. One of them enters the FPGA control system through PLL0 and is connected to the internal clock management. The module de-skews and increases the fan-out to improve the clock quality, and sends the improved clock to the image control; another clock PLL1 is sent to the clock management module to improve the signal quality, and then sends the clock to the outside, It is for lighting.

Description

A kind of TTL video output system and its method

technical field

The invention belongs to the field of liquid crystal technology, and more specifically relates to a TTL video output system. At the same time, the invention also relates to a TTL video output method.

Background technique

The use of liquid crystal display modules (Liquid Crystal Display Module, hereinafter referred to as modules) and related liquid crystal display devices (hereinafter referred to as devices) has become very common, and because of TTL (Transistor TransistorLogic, transistor-transistor logic level) signal stability Reliable, high transmission rate, and low power consumption, many modules and devices use this signal as a display interface for receiving video images.

During the production, debugging and display process of the module and its equipment, it is necessary to generate a TTL video signal through the video image signal source or video adapter board (hereinafter referred to as the video source) to provide the source of the module display signal, so ensure that the video The correctness and reliability of the video signal generated by the source are the prerequisites for ensuring the display of the module.

In terms of TTL video transmission, since the internal signal needs to go through the package bonding wire, the connection wire on the PCB board and the through hole, it can be connected to other chips. If TTL level is used as the output interface, various parasitic parameters will lead to data loss. Rise/fall times and synchronous matching between multiplexed data are severely degraded. Therefore, TTL level is generally used as video transmission, the speed is low, and the picture displayed is distorted.

Contents of the invention

The purpose of the present invention is to solve the shortcomings in the prior art, and propose a TTL video output system and method thereof, which can improve the TTL video transmission effect without signal distortion.

To achieve the above object, the present invention provides the following technical solutions:

A TTL video output system includes a PLL chip and an FPGA control system, the PLL chip includes a first clock signal and a second clock signal of the same frequency, and the FPGA control system includes a first clock management module, a second clock management module and an image Output control module, the first clock signal, the first clock management module and the image output control module are sequentially connected, the image output control module outputs an image signal that does not contain a clock, and the second clock signal is connected to the The second clock management module, the second clock management module outputs an image clock.

The present invention also provides a kind of TTL video output method, comprises the steps:

S1. After the upper computer sends the playback parameters and playback control, control the external PLL chip to output two clocks with the same frequency and phase, among which PLL0 is used to control the output of image data and line and field synchronization signals; PLL1 is used to control the clock of lighting; Since PLL1 and PLL0 are signals of the same frequency and phase at the beginning, the timing of the output is a synchronous signal at the source;

S2. If the lighting is abnormal, the host computer sends out phase control parameters, and the clock phase of the output image has been adjusted. At this time, the clock and data output by the source end are not synchronized, and due to the phase shift generated when the signal passes through the system, the output reaches the terminal. It will achieve lighting effect.

Preferably, in S2, the adjustment is made by observing the image state.

Technical effect and advantage of the present invention: TTL video output system and method thereof provided by the present invention, its external PLL chip is controlled by FPGA control system, and external PLL chip can output two clocks and send to FPGA, and these two clocks are the same frequency , but the purposes are different. One of them enters the FPGA control system through PLL0 and connects to the clock management module to de-skew and increase the fan-out to improve the clock quality and send the improved clock to image control; the other clock PLL1 is sent to In the clock management module, to improve the signal quality, and then send the clock to the outside for lighting; the image output control module, the clock for controlling the timing of this part of the image output and the clock for lighting are not the same clock, this module is working At the time, only the data signal of the image and some line and field synchronization signals are output, which solves the problem of improving the TTL video transmission effect without signal distortion.

Description of drawings

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

Fig. 2 is a control flow chart of the present invention.

Fig. 3 is an analysis diagram of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, the present invention provides a kind of TTL video output system, comprises PLL chip and FPGA control system, and this PLL chip comprises the first clock signal of the same frequency and the second clock signal, and this FPGA control system comprises the first clock management system module, a second clock management module, and an image output control module, the first clock signal, the first clock management module, and the image output control module are sequentially connected, and the image output control module outputs an image signal that does not contain a clock , the second clock signal is connected to the second clock management module, and the second clock management module outputs an image clock.

As shown in Figure 2, the present invention also provides a kind of TTL video output method, comprises the steps:

S1. After the upper computer sends the playback parameters and playback control, control the PLL chip to output two clock signals with the same frequency, one of which is used to control the image data and the output of line and field synchronization signals, and the other clock signal is used for lighting. clock control;

S2. If the lighting is abnormal, the upper computer sends out phase control parameters to adjust the clock phase of the output image, and the output reaches the terminal to achieve the lighting effect. In S2, adjust by observing the image state; because the same set of cables and fixtures can cause a certain phase change, therefore, only one adjustment is required.

During the lighting process, we will encounter the situation that the output waveform of the source terminal is synchronous, but the terminal is not synchronous. As a result, the lighting effect is abnormal. It is not difficult to analyze. From the definition of Fourier series, it can be known that all periodic signals can be superimposed with sine waves of different frequencies (here refers to the general term of sine and cosine). When a sine wave with a fixed frequency enters any complex system, its output will only change the amplitude and phase of the input waveform, and will not change the shape of the waveform. Therefore, due to the frequency difference between the clock and the data, the clock and the signal are skewed after reaching the terminal. As shown in Figure 3.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some of the technical features may be replaced by equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the within the protection scope of the present invention.

Claims (3)

1. a kind of TTL video output system is characterized in that, comprises PLL chip and FPGA control system, and this PLL chip comprises the first clock signal and the second clock signal of same frequency, and this FPGA control system comprises the first clock management module, the first clock signal Two clock management modules and an image output control module, the first clock signal, the first clock management module and the image output control module are connected in sequence, the image output control module outputs an image signal that does not contain a clock, the The second clock signal is connected to the second clock management module, and the second clock management module outputs an image clock. 2. a kind of TTL video output method according to claim 1, is characterized in that: comprise the steps: S1. After the upper computer sends the playback parameters and playback control, control the PLL chip to output two clock signals with the same frequency, one of which is used to control the image data and the output of line and field synchronization signals, and the other clock signal is used for lighting. clock control; S2. If the lighting is abnormal, the upper computer sends out phase control parameters to adjust the clock phase of the output image, and the output reaches the terminal to achieve the lighting effect. 3. A TTL video output method according to claim 2, characterized in that: in S2, the adjustment is made by observing the image state.