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VII LCD CONTROLLER BLOCK: LCD CONTROLLER
S1C33L03 FUNCTION PART EPSON B-VII-2-25
A-1
B-VII
LCDC
Inverting and Blanking the Display
The display can be blanked (the entire screen turned black) without rewriting the contents of the display memory.
Setting DBLANK (D3)/LCDC mode register 1 (0x39FFE2) to "1" causes the FPDAT signal to go low, blanking
the display. Setting it to "0" turns the display back on.
Furthermore, the display can be inverted simply by manipulating bits. Setting INVDISP (D0)/LCDC mode register
1 (0x39FFE2) to "1" inverts the display, and setting it to "0" returns the display to normal. This is accomplished by
inverting the display data output from the look-up tables, rather than by inverting the pixel data in the display
memory.
The screen can be made to blink using these operations. Make sure switching takes place within the vertical non-
display period (VNDPF = "1").
Portrait Mode
Depending on the applications used, the LCD panel may normally be used while positioned horizontally, and may
sometimes need to be used after being turned 90 degrees into a vertical position. Generally, image data should be
rotated by software, which, however, adversely affects not only the display performance but also the performance
of the entire system. The LCD controller supports this function in the hardware, enabling images to be rotated 90
degrees without increasing the load on the CPU. This function can be accomplished by setting the LCD controller
to portrait mode. Depending on differences in memory usage and performance, two types of portrait modes (default
and alternate portrait modes) are available.
Default portrait mode
Although inferior to alternate portrait mode in terms of display performance, default portrait mode is superior
in terms of current consumption, as it enables the use of a slower clock. In this mode, the horizontal size of
images must be increased by the power of 2. To display a horizontal 240-pixel image in default portrait mode,
for example, memory must be available for 256 pixels (2
8
) equivalent of horizontal size.
Physical memory
start address
Screen 1
start address
Unused
area
240 pixels
240 lines
256 pixels
320 lines
320 pixels
Display memory LCD panel
Image
Line 1
Line 240
A B E
DC
Image
A B E
DC
Figure 2.20 Image Rotation in Default Portrait Mode
Figure 2.20 shows the relationship between the display memory and the LCD panel in cases in which a 320 ×
240-pixel LCD panel is rotated 90 degrees to display a 240 × 320-pixel image.
The control procedure described below is based on the assumption that the LCD panel is used in 8-bpp mode.
1. Make settings necessary to use an LCD panel consisting of 320 pixels horizontally and 240 lines
vertically. If necessary, set it for display in normal (landscape) mode.
2. To switch from landscape mode to portrait mode, temporarily clear the display memory in advance. If
switched over without clearing the display memory, the display may be distorted for a certain period.
3. If the LCD panel was split into two screens in landscape mode, reset the S1VSIZE[9:0] (D[9:0])/screen 1
vertical size register (0x39FFF3, 0x39FFF2) by setting a new value above the vertical resolution of the
LCD panel. In portrait mode, the LCD panel cannot be split for display on screen 2.