LCD Controller Registers
11-27
LCD Controller
The 16-bit STN mode appears in the frame buffer memory as follows: 5-6-5.
Table 11–14. 16-Bit STN Data in Frame Buffer
Red
Green
Blue
Pins
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Data
R4
R3
R2
R1
R0
G5
G4
G3
G2
G1
G0
B4
B3
B2
B1
B0
The 16-bit STN mode sends only 12 bits to the dither logic (bits 11, 6, 5, and
0 are not sent to dither logic). These bits are the 4 MSBs of each color.
Figure 11–10 shows the dither logic.
Figure 11–10.
Dither Logic
4
are not used as image data, and are ignored.
The 16-bit STN resolution is equal to the
12-bit STN resolution (3375 colors).
NOTE:
Red bit 11
Green bits 6, 5
Blue bit 0
Dither Logic
Bits: 15 14 13 12
10 9 8 7
4 3 2 1
11
0
6 5
1
4
1
4
1
The 12-BPP (5-6-5) mode can be used if the operating system does not
support 12 BPP in the frame buffer. Data is arranged in 16-BPP instead, but
only 12 bits are dithered and sent to the display.
16 Bits Per Pixel STN Mode
The 16-bit per pixel (BPP) STN mode is used to enable display of 16 BPP data
on a passive color display. When this bit is enabled, data stored in the frame
buffer as 16 BPP (5 bits red, 6 bits green, 5 bits blue) is converted internally
to 12 bits (4 bits red, 4 bits green, 4 bits blue) for input into the STN dither logic.
This bit does not affect 12 BPP mode.