CS89712 Datasheet, PDF (102/170 Pages) Cirrus Logic – HIGH-PERFORMANCE, LOW-POWER SYSTEM-ON-CHIP WITH 10BASE-T ETHERNET CONTROLLER

CS89712
3.11.2 PALLSW Least Significant Word — LCD Palette Register (address 0x8000.0580)
31:28
27:24
23:20
19:16
15:12
11:8
7:4
3:0
Grayscale
Grayscale Grayscale Grayscale Grayscale Grayscale Grayscale Grayscale
value for pixel value for pixel value for pixel value for pixel value for pixel value for pixel value for pixel value for pixel
value 7
value 6
value 5
value 4
value 3
value 2
value 1
value 0
The least and most significant word LCD palette registers make up a 64-bit read / write register which maps the log-
ical pixel value to a physical grayscale level. The 64-bit register is made up of 16 x 4-bit nibbles, each nibble defines
the grayscale level associated with the appropriate pixel value. If the LCD controller is operating in two bits-per-pixel,
only the lower 4 nibbles are valid (D[15:0] in the least significant word). Similarly, one bit-per-pixel means only the
lower 2 nibbles are valid (D[7:0]) in the least significant word.
3.11.3 PALMSW Most Significant Word — LCD Palette Register (address 0x8000.0540)
31:28
27:24
23:20
19:16
15:12
11:8
7:4
3:0
Grayscale
Grayscale Grayscale Grayscale Grayscale Grayscale Grayscale Grayscale
value for pixel value for pixel value for pixel value for pixel value for pixel value for pixel value for pixel value for pixel
value 15
value 14
value 13
value 12
value 11
value 10
value 9
value 8
The pixel to grayscale level assignments and the actual physical color and pixel duty ratio for the grayscale values
are shown in Table 56. Note that colors 8–15 are the inverse of colors 7–0 respectively. This means that colors 7
and 8 are identical. Therefore, in reality only 15 grayscales available, not 16. The steps in the grayscale are non-
linear, but have been chosen to give a close approximation to perceived linear grayscales. The is due to the eye
being more sensitive to changes in gray level close to 50% gray (See PALLSW description).
Grayscale Value
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Duty Cycle
0
1/9
1/5
4/15
3/9
2/5
4/9
1/2
1/2
5/9
3/5
6/9
11/15
4/5
8/9
1
% Pixels Lit
0%
11.1%
20.0%
26.7%
33.3%
40.0%
44.4%
50.0%
50.0%
55.6%
60.0%
66.7%
73.3%
80.0%
88.9%
100%
% Step Change
11.1%
8.9%
6.7%
6.6%
6.7%
5.4%
5.6%
0.0%
5.6%
5.4%
6.7%
6.6%
6.7%
8.9%
11.1%
Table 56. Grayscale Value to Color Mapping
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DS502PP2