26 LCD CONTROLLER (LCDC)
26-18
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
8-bpp mode (256 colors)
In 8-bpp mode, each byte in the VRAM corresponds to one pixel. The bit[7:5] (3 bits), bit[4:2] (3 bits), and
bit[1:0] (2 bits) in each byte represent the Red, Green, and Blue intensities, respectively, of the pixel when the
look-up table is bypassed or an LUT entry number (0 to 255) when the look-up table is used.
(1,0)
(0,0)
R2 R1 R0 G2 G1 G0 B1 B0
LCD
I/F
LCD
I/F
LUT
entries 0 to 255
(3,0)
(2,0)
VRAM
Display start address
Byte address offset
8 bit / 1 pixel
When LUT is bypassed
When LUT is used
FPDAT signals
FPDAT signals
LUT entry number
(x, y)
MSB
LSB
Brightness data
in the specified
entry
+0 +1
(5,0)
(4,0)
+2
(7,0)
(6,0)
+3
(9,0)
(8,0)
+4
(11,0)
(10,0)
+5
(13,0)
(12,0)
+6
(15,0)
(14,0)
+7 +8 +9 +10 +11 +12 +13 +14 +15
b[7:0]
5.5.7 VRAM Data Format in 8-bpp Mode
Figure 26.
Example
VRAM start address: 0x10000000
Screen width:
320 pixels
LUT:
Bypassed
LCD characteristics: Data = 0
→
Low LCD brightness
Display image
Coordinates
(0, 0)
320 pixels
VRAM data
Address
0x1000 0000
0x1000 0140
0x1000 0280
:
0x00 0xe0 0x1c 0x07 .....
0xff 0x1f 0xe7 0xfc .....
0x00 0x49 0xb6 0xff .....
: : : :
320 bytes / line
Note) Display may be inverted depending on the LCD panel used.
5.5.8 Example of VRAM Data in 8-bpp Mode
Figure 26.
12-bpp mode (4K colors)
In 12-bpp mode, each 12-bit data in the VRAM corresponds to one pixel. Display data must be manipulated
in 3-byte units that consist of an even and odd X coordinate pixel pair. The bit[11:8] (4 bits), bit[7:4] (4 bits),
and bit[3:0] (4 bits) in each 12-bit data represent the Red, Green, and Blue intensities, respectively, of the pixel.
This mode does not support the look-up table.
(1,0)
(0,0)
R3 R2 R1 R0 G3 G2 G1 G0
B3 B2 B1 B0 R3 R2 R1 R0
G3 G2 G1 G0 B3 B2 B1 B0
LCD
I/F
(3,0)
(2,0)
VRAM
Display start address
Byte address offset
12 bit / 1 pixel
LUT bypassed
FPDAT signals
Byte 2
Byte 1
Byte 0
(x, y)
MSB
LSB
Odd
pixel
Even
pixel
+0 +1
(5,0)
(4,0)
+2
(7,0)
(6,0)
+3 +4 +5 +6 +7 +8 +9 +10 +11
(9,0)
(8,0)
+12 +13 +14
Figure 26.5.5.9 VRAM Data Format in 12-bpp Mode