Outdoor LED screen application is very extensive, technology development and research in design using dual-RAM technology to organize the data used to control the display of the rectangle control system, improves memory efficiency of the information when the vertical loop, significantly reduces the memory usage of your data, and requirements for the refresh rate is not very high.
1, LED display data organization
Need to show an area less than or equal to the actual display area, the use of static display. But most of the time range is greater than or equal to the actual display area needs to be displayed, as shown in Figure 1. To simplify the analysis of the problem, this article sets the height of the display area for the LED display 4 times times the height, width of width equal to the LED display. Set the display height of Lh, width Lw, displays regional high Dh=4Lh, width Dw=Lw. Monochrome display, as described in this article, and Bw=Bn=8 (Bw for the number of scan lines, Bn for the width of the output data), as shown in Figure 1.
Display area map
For an LED display, height width Lw and Lh is finalized, arrangement of display panels will determine. Panels-distance between two adjacent scan lines to the Sw, display Bw scanning lines, namely, Y0,Y1, and YBw-1. Sw row corresponds to one of the displayed data, each point on the display one that corresponds to a byte in memory. Bw scanning lines respectively, pointing to: Y0=O,Y1=Sw, and, BBw-1= (Bw-1) Sw. Display data by using static methods to display blocks a, b, c, d organize displayed data. Display block on first organized a display of information (x is the column number):
` X=0, the current scan line the line intersects the O column of the displayed data according to the D0,D1, and, DBw-1 is stored in memory in the order of the first storage unit.
a increase the x value of 1, the row corresponding to the x value of the current scan line column displays the data stored in the memory of the intersecting points of the next storage unit. Until X=O to X=Dw-1 Dw data are all stored sequentially in memory.
b Bw scanning lines down one row, repeat ` and a steps until Y0 moved to the Sw-1 line.
c end of data organization.
Display areas b, c, and d, respectively, in accordance with a method of data organization to organize displayed data. Organizations displayed after data blocks a, b, c, d in order stored in the RAM0 and RAM0 appears in blocks a, b, c, d, a, b, c, d in order copy to RAMl, any two adjacent display block displays data in two blocks of storage in RAM has the same address range. RAM0 and RAMl shows data corresponding to the memory of the relationship as shown in Figure 2.
Scan Group 1 from Y0=0 to Y0=Sw-1, corresponding to display block a, organization of data stored in memory, you can direct output to display data; scan set 2 from the Y0=Lh to the Y0=Lh+Sw-1, corresponding to display block b has also been organized, you can direct output. But scanning Group 3, where it is unusual, it scanned lines correspond to two blocks a and b, respectively; the O,1, and A scan Bw-1 scan line corresponding display block Group 1 1, 2, and, Bw-2; Bw-1 scan line corresponds to display block b scan section O of 2 sets of scan lines. If scan corresponds to groups 3 to be displayed on the display of the screen data, we must at the same time used to scan groups 1, 2, and, Bw-1 scan line and the scan section O of 2 sets of scan line display data as the output data of the organization. Due to the display of blocks a and b show the data is organized, then we should take the RAM0 D0,D2, and, DBw-1 and RAMl D0 as a Bw data output to the display screen, this requires two pieces of RAM simultaneously try to select the desired output 2Bw-Bw, as the output data and the Bw data is continuous.
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Article Source: LED full color single-chip control system design
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