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LH75400/01/10/11 (Preliminary) User's Guide
13.2.5 Grayscale Algorithm
A patented grayscale algorithm drives the monochrome and color STN panels.
• For monochrome displays, the gray-scale algorithm provides 15 gray scales.
• For color displays, the 3-color components (red, green, and blue) are grayscaled simul-
taneously. This results in 3,375 colors (15 × 15 × 15) being available for Color STN Mode.
The grayscaler transforms each 4-bit gray value into a sequence of activity-per-pixel over
several frames, relying partially on the display characteristics to provide the representation
of gray scales and color.
Red, green, and blue pixel data bit values from the gray scaler are shifted concurrently into
the respective registers in the upper and lower panel formatter. The upper and lower panel
formatters each comprise three 3-bit (red, green, and blue) shift-left registers. When
enough data is available, a byte is constructed by multiplexing the registered data to the
correct bit position to satisfy the LCD panel's RGB data pattern. The byte transfers to the
3-byte FIFO, which has sufficient space to store eight color pixels.
The CLCDC has four individually maskable interrupt conditions associated with a single
combined interrupt. The single combined interrupt is asserted if any of the combined inter-
rupt conditions are asserted and unmasked.
13.2.6 LCD Panel Resolutions
LCD panel resolution is expressed as the total number of horizontal pixels multiplied by the
total number of vertical pixels. The CLCDC supports STN, TFT, HR-TFT, and AD-TFT
LCD panels. The only requirement is for the width to be divisible by 16; there is no limit on
height. Examples of resolutions supported include:
• 160 × 120
• 320 × 200
• 320 × 240
• 640 × 200
• 640 × 240
• 640 × 480 8-bit Mode (this resolution requires significant processor bandwidth)
Color Liquid Crystal Display Controller
7/15/03
13-7
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