27 GRAPHICS ENGINE (GE)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
27-3
The work area cannot be configured beyond 4,096 pixels
×
4,096 pixels even if an external large capacity
VRAM is connected.
If the whole of an object/image drawn by a command is located outside the work area (coordinates are speci-
fied in signed 16-bit values), a work area over error occurs (an interrupt can be generated). If only a part of an
object/image is beyond the work area, the drawing within the work area is performed without an error.
Note: If the X or Y coordinate in the object, which is generated by a drawing command, exceeds the
range from -32,768 to 32,767, the GE module may not draw the object properly.
The table below lists VRAM capacities required for different work area size and bpp mode (color depth).
3.1.1 Work Area Size and VRAM Capacity
Table 27.
Color depth
VRAM capacity
16 bpp (65,536 colors)
Number of all pixels
÷
2 (words)
8 bpp (256 colors)
Number of all pixels
÷
4 (words)
4 bpp (16 colors/16-level gray scale) Number of all pixels
÷
8 (words)
2 bpp (4 colors/4-level gray scale)
Number of all pixels
÷
16 (words)
1 bpp (2 colors/2-level gray scale)
Number of all pixels
÷
32 (words)
(Number of all pixels = Horizontal pixel count
×
Vertical pixel count of work area)
Note: The work area width (data size) must be specified in word (32 bits) increments. If an incorrect
value is specified, the GE corrects it to the word (32 bits) boundary value larger and closest to the
specified value.
The data size depends on the bpp mode. Furthermore, when the work area is rotated, its width
and height must be reset according to the rotation angle. Therefore, VWIN_W[11:0] and VWIN_
H[11:0] should be set after setting the bpp mode and the angle of work area rotation. See Table
27.3.1.4 for VWIN_W[11:0] and VWIN_H[11:0] settings for different bpp modes and rotation angles.
Settings for VRAM address calculation
In order for the GE module to write objects/images specified with coordinate values to the appropriate
VRAM location, set the information required for converting coordinates within the work area into VRAM
addresses as below.
Work area start address
Set the VRAM address corresponding to the origin point (0, 0) of the work area to VWIN_ADDR[31:2]/
GE_WK_ADDR register.
Note: Set a 1K-byte boundary address for the work area start address.
Color depth
The correspondence between coordinates and VRAM addresses/bits depends on the color depth (bits
per pixel). Set the bpp mode using DISP_BPP[2:0]/GE_DISP_CFG register.
3.1.2 Color Depth Settings
Table 27.
DISP_BPP[2:0]
Color depth
0x7 to 0x5
Reserved
0x4
16 bpp (65,536 colors)
0x3
8 bpp (256 colors)
0x2
4 bpp (16 colors/16-level gray scale)
0x1
2 bpp (4 colors/4-level gray scale)
0x0
1 bpp (2 colors/2-level gray scale)
(Default: 0x0)
Relationship between LCD display and work area
The embedded LCDC module supports a virtual screen function to use an image area larger than the LCD
panel size. Any location in the virtual screen area can be displayed on the LCD panel. This allows multiple-
screens to be configured in the VRAM and panning/scrolling large images.