27 GRAPHICS ENGINE (GE)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
27-15
Sync with LCD display
The LCDC synchronization function can be enabled or disabled.
Sync Enable bit = 1: Synchronized
Sync Enable bit = 0: Not synchronized
When this function is enabled (synchronous mode), the GE starts drawing objects/images (writing to the work
area) in sync with the LCD non-display period start timings and drawings are performed in the non-display
periods. This makes it possible to eliminate screen flicker. When rewriting the area currently displayed on the
LCD panel, normally enable the LCDC synchronization function.
Before using this function, select either vertical non-display period or horizontal non-display period as the
rewrite period using SYNC_TYPE/GE_DISP_CFG register. Horizontal non-display period is selected when
SYNC_TYPE is 0 (default) and vertical non-display period is selected when it is set to 1.
Note, however, that drawing time may exceed the non-display period if it is complicated.
When this function is disabled (asynchronous mode), the GE draws objects/images without a delay. Asynchro-
nous mode is useful when drawing objects/images on an area out of the LCD display range or high-speed pro-
cessing is required.
Writing effects
When the GE writes object/image data to the work area, a writing effect can be applied to the data to be written.
The GE provides four effects listed in the table below and one of them can be selected.
3.5.2 Writing Effect Selections
Table 27.
Write Effect Setting[2:0] bits
Writing effect
0x7–0x4
Reserved
0x3
Rewrite
0x2
Mesh
0x1
XOR
0x0
Normal (Fill)
The writing effect is applied to the data immediately before being written to the work area after other drawing
effects have been applied.
Normal (Fill)
(Write Effect Setting[2:0] bits = 0x0)
No writing effect is applied. Image data is written to the work area without being modified.
XOR
(Write Effect Setting[2:0] bits = 0x1)
Performs an XOR operation on the data to be written to and the current data on the work area, and writes
the results to the work area. If the pixels located at the same position have the same color, the pixel is drawn
in black.
Mesh
(Write Effect Setting[2:0] bits = 0x2)
Overlays a mesh pattern on the object when written to the work area. This function can be used to produce
a halftone and to highlight display contents.
The mesh pattern is configured using MESH_RW[1:0]/GE_MESH register for specifying the horizontal
line width and MESH_CW[1:0]/GE_MESH register for specifying the vertical line width.
3.5.3 Mesh Pattern Settings
Table 27.
MESH_RW[1:0]/MESH_CW[1:0]
Mesh size
0x3
4 pixels
0x2
Reserved
0x1
2 pixels
0x0
1 pixel
(Default: 0x0)