Today, with the rapid development of science and technology,LED displayIt can be seen everywhere in our daily life, and LEDs are widely used in large screens such as commercial and media advertisingto showFor example, the American monument “New York Times Square” has designedExternal advertisingLarge screen. EarlyLED displayThe application scenarios are mainly doors advertising, and the monochrome screen is used, and now it is the full color screen. With the increase in color and resolution requirements, LEDs are increasingly small, not only more the requirements for materials, heat dissipation and the heat process are high, but the more the performance of integrative display solutions are high. The first monochrome cards did not require a high control zone and a display effect, and the display driver of the monochrome screen was unique, and the solution was essentially a MCU master to finish the scanning and driving display. By reading the data displayed at the MCU for data reorganization, the MCU leads to the data to be displayed on the screen, then grants the data to be updated to complete the data.
With the development of display demand on the market, the Les Grande screens advertising shops uses a color LED module display. Due to improving resolution and color effects, the performance and the number of main control control pins did not meet the requirements. Currently, FPGAs have enormous advantages in the display effect, whether it is rapid implementation or display costs, and to make FPGA of the consumer solution chosen by the main systems manufacturers in the LED display. As the figure shows, Runxin Technology recommends an anlu LED card solution to customers. The solution requires the transmission of video signals, control signals and other data to the reception card via the Gigabit network. Each reception card controls a certain number of screens and in cascades the data on the next reception card.
FPGA mainly completes the reception and transmission of the Gigabit network and decodes the data received. A gama correction table is necessary to correct the data displayed, and the LED screen must be corrected point by point. The gray value of the pixel must also be calculated by image algorithm, and the final processed data is written in the SDRAM cache. The LED scanning module is generatedLED driverBalayage synchronization and the gray level of the chip have read the data that must be brushed on the LED of the SDRAM as a function of the scanning method. The following figure is a logical module treated internally by FPGA.
The most at the heart is the LED scanning control module. Color LED screens generally use a bit bit bit-free sweeping method to reach the gray level image display. For LED screens with 8 bits of gray levels, the principle of “19 -field scanning” is generally used to reach a level of level 256. The update of the display data of LED display screens generally adopts the serial output mode. For example, a static LED -colored display screen designed with 595 is designed. Depending on the principle of “19 field fields”, for screens determined by resolution and other specifications, when the standard shift clock is determined, the refresh frequency of the display screen and the light efficiency of the LED (the proportion of the longest lighting time of the LED in a single scan period) will be determined. Taking the example of the theory of “scan at 19 fields” 8 bits, the so -called bits lighting by bit means extracting a top room from top to top or up to the lower byte data, and illuminating the corresponding pixels in 8 times. The corresponding light time of each bit is different from the service cycle of the stop time. If the lighting time multiplies from the bottom to the top, the combined lighting time will have 256 combinations. Define the lighting time corresponding to the D0 bit and the time of time as a unit of time. Setted on T to obtain the lighting and stop times of each bit indicated in Table 1.
In the real design, T is also the time required to update serial data on the LED display. The total time indicated in Table 1 is an entire multiple multiple, so the total time occupied by each bit of data can be timed by refreshing the screen data once. When designing the LED display, the LED on and deactivated in the entire screen can be controlled by the main command line in. When the lighting time is ≥ 1 t, the control display is in the constant state. When the lighting time is <1 t, the monitoring of the brightness of the corresponding bits can be obtained by controlling in to generate a form of control wave with the corresponding service cycle. This scanning method can make the level 256 gray screen in color. LED manufacturers will adjust the specific scanning method depending on the different LED modules and the display experience to obtain better display effects.
Compared to the development and improvement of LED control cards scanning technology in the FPGA function, the corresponding LED control card diagrams and forms and even the LED screen control systems have developed considerably. Based on the topology structure of the Gigabit Network Cascade Method before the LED control card with LED display and control platforms which have extremely strict requirements on the stability of the system functioning, many LED public security display systems, the procuratorial and judicial screens to control screens are based on the topology of the stars and have at the same time Master-slave safeguard. From the point of view of the form of development of LED control cards, the development of the previous monomotic multi-interface card with the integrated LED control card of the LED light card has the advantages of reducing the area, reducing energy consumption, high expansion and a simple structure.
From the point of view of LED display applications, the EG4 series of ANLU FPGA has made localized and prospective conceptions on the LED market. It solves the bandwidth, the IO, the area, the cost and other problems for customers thanks to the nuclear encapsulation of SDRAM. The power supply and the structure of the friendly soil pins give customers a competitive advantage of PCB costs, and also provides alternative packaging models and high -speed series interfaces for devices of the same level as foreign countries. Based on ANLU FPGA, Runxin Technology recommends a driver card design solution directly connected to the LED screen to customers. This solution includes its own AST asynchronous transmission interface at high speed, Core M3, ADC, etc., with a full chip function to meet all LED display needs. The FPGA reads the Image data data U, transmits the data via the AST issuer, and the pilot card connects directly to the LED screen chip via the Hub75 interface and finally displays the image in real time. Compared to traditional display modules, this system has higher reliability, an integrated lighting player, no cables and a reduced EMI. The AST transmission distance and the transmission rate are variable, adapting to screens between different points. Real -time feedback voltage, temperature, screen working time, high cost performance, high system integration and simple debugging process. With market development and technology, FPGA will be more widely used in LED screens, and Runxin Technology will continue to introduce better LED display solutions to customers.
Source: Runxin Technology Fortune WeChat Public account
