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LCD CONTROLLER S3C2440A RISC MICROPROCESSOR
15-8
Display Types
The LCD controller supports 3 types of LCD drivers: 4-bit dual scan, 4-bit single scan, and 8-bit single scan display
mode. Figure 15-2 shows these 3 different display types for monochrome displays, and Figure 15-3 show these 3
different display types for color displays.
4-bit Dual Scan Display Type
A 4-bit dual scan display uses 8 parallel data lines to shift data to both the upper and lower halves of the display at
the same time. The 4 bits of data in the 8 parallel data lines are shifted to the upper half and 4 bits of data is
shifted to the lower half, as shown in Figure 15-2. The end of frame is reached when each half of the display has
been shifted and transferred. The 8 pins (VD[7:0]) for the LCD output from the LCD controller can be directly
connected to the LCD driver.
4-bit Single Scan Display Type
A 4-bit single scan display uses 4 parallel data lines to shift data to successive single horizontal lines of the display
at a time, until the entire frame has been shifted and transferred. The 4 pins (VD[3:0]) for the LCD output from the
LCD controller can be directly connected to the LCD driver, and the 4 pins (VD[7:4]) for the LCD output are not
used.
8-bit Single Scan Display Type
An 8-bit single scan display uses 8 parallel data lines to shift data to successive single horizontal lines of the
display at a time, until the entire frame has been shifted and transferred. The 8 pins (VD[7:0]) for the LCD output
from the LCD controller can be directly connected to the LCD driver.
256 Color Displays
Color displays require 3 bits (Red, Green, and Blue) of image data per pixel, so the number of horizontal shift
registers for each horizontal line corresponds to three times the number of pixels of one horizontal line. These
results in a horizontal shift register of length 3 times the number of pixels per horizontal line. This RGB is shifted to
the LCD driver as consecutive bits via the parallel data lines. Figure 15-3 shows the RGB and order of the pixels in
the parallel data lines for the 3 types of color displays.
4096 Color Displays
Color displays require 3 bits (Red, Green, and Blue) of image data per pixel, and so the number of horizontal shift
registers for each horizontal line corresponds to three times the number of pixels of one horizontal line. This RGB
is shifted to the LCD driver as consecutive bits via the parallel data lines. This RGB order is determined by the
sequence of video data in video buffers.