![](http://datasheet.mmic.net.cn/30000/MC80C52TXXX-25P883D_datasheet_2371972/MC80C52TXXX-25P883D_1149.png)
1149
11028E–ATARM–22-Apr-13
SAM9G46
The lookup table can be accessed by the host in R/W mode to allow the host to program and
check the values stored in the palette. It is mapped in the LCD controller configuration memory
map. The LUT is mapped as 16-bit half-words aligned at word boundaries, only word write
access is allowed (the 16 MSB of the bus are not used). For the detailed memory map, see
The lookup table contains 256 16-bit wide entries. The 256 entries are chosen by the program-
mer from the 216 possible combinations.
In STN Monochrome, only the four most significant bits of the red value are used (16 gray
shades). In STN Color, only the four most significant bits of the blue, green and red value are
used (4096 colors).
In TFT mode, all the bits in the blue, green and red values are used. The LCDD unused bits are
tied to 0 when TFT palletized configurations are used (LCDD[18:16], LCDD[9:8], LCDD[2:0]).
48.6.2.6
Dithering
The dithering block is used to generate the shades of gray or color when the LCD Controller is
used with an STN LCD Module. It uses a time-based dithering algorithm and Frame Rate Con-
trol method.
The Frame Rate Control varies the duty cycle for which a given pixel is turned on, giving the dis-
play an appearance of multiple shades. In order to reduce the flicker noise caused by turning on
and off adjacent pixels at the same time, a time-based dithering algorithm is used to vary the
pattern of adjacent pixels every frame. This algorithm is expressed in terms of Dithering Pattern
registers (DP_i) and considers not only the pixel gray level number, but also its horizontal
coordinate.
STN Mono
4
Non-palletized
STN Color
1, 2, 4, 8
Palletized
STN Color
16
Non-palletized
Table 48-10. Lookup Table Structure in the Memory
Address
Data Output [15:0]
00
Red_value_0[4:0]
Green_value_0[5:0]
Blue_value_0[4:0]
01
Red_value_1[4:0]
Green_value_1[5:0]
Blue_value_1[4:0]
...
FE
Red_value_254[4:0]
Green_value_254[5:0]
Blue_value_254[4:0]
FF
Red_value_255[4:0]
Green_value_255[5:0]
Blue_value_255[4:0]
Table 48-9.
Palette Configurations
Configuration
Palette
DISTYPE
PIXELSIZE