LED display control system design based on dual RAM technology (full version)
Introduction
The long-screen LED display is widely used in life. The control circuit of this display is simple, the scanning line is limited, and the display information is not large. When the amount of information displayed is relatively large, the general long-screen display is used, and the display information is too slow. Even with the display screen of the ultra-long screen, the data output rate is slow, and the refresh rate of the display does not necessarily satisfy the display. demand. The rectangular display shows that the amount of information on one screen is large, and the height of the display can be expanded as needed. There is no limitation on the frequency, which can make up for some problems in displaying information on the long display. In this paper, the control system data used to control the rectangular display uses double RAM technology, which improves the memory efficiency when the information is displayed vertically, greatly reduces the occupation of data memory, and the requirements for refresh frequency are not very high [1]. .
1 Display data organization
Most of the time, the area to be displayed is greater than or equal to the actual displayed area. When it is equal or less, it is static display. Figure 1 shows that the area to be displayed is larger than the actual displayed area. In order to simplify the analysis of the problem, this article will show that the height of the area is set to 4 times the height of the LED display, the width is equal to the width of the LED display, and the height of the display is , width is
, display area height
,width
, scan lines
This article uses a monochrome display as the description object, and
(
For the output data width), as shown in Figure 1.
Figure 1 shows the area map
For an LED display width is , height is
After the determination, the arrangement of the display unit boards is also determined, and the distance between the two scanning lines adjacent to the unit board is
, the display has
Scan lines, respectively
,
,...
,each
The row corresponds to one bit of display data, and each dot on the display corresponds to a bit of a byte in the memory. The starting position of each scan line is shown in Figure 1.
Strip scan lines point to
,
,...,
. Data is displayed on the display blocks A, B, C, and D by the static display data organization method [2]. First, organize the display information of display block A:
1 , that is, the display data of each point of the current scan line intersecting the 0th column is pressed.
,
,...,
The order is stored in the first location of the memory.
2 The value is increased by 1, the current scan line is
The display data of the values ​​corresponding to the points at which the columns intersect is stored in the next memory location of the memory.
3 repeat the operation of step eq oac (â—‹, 2) 2 steps, will to
of
The data is all stored in memory in order.
4 The strip scan line moves down one line, repeating steps eq oac(â—‹,1)1 to eq oac(â—‹,3). until
move to
Time.
5 data organization is over.
The display areas B, C, and D are organized in accordance with the data organization of A to display the display data. The organized display data blocks are stored in RAM0 in the order of A, B, C, and D, and then the display data blocks A, B, C, and D in RAM0 are copied to RAM1 in the order of B, C, D, and A. The display data of any two adjacent display blocks respectively have the same address storage area in both RAMs. The correspondence between the display data of RAM0 and RAM1 and the memory is as shown in FIG. 2.
Figure 2 Arrangement between data block and memory
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