VII LCD CONTROLLER BLOCK: LCD CONTROLLER
Grayscale-mode look-up tables
In grayscale mode, the LCD controller uses only the green look-up table. For display in grayscale mode, select the data to be written to the look-up table from the 16 gray levels represented by 4 bits. The data 0x0, 0x1, 0x8, and 0xF represent black, 93.75% gray, 50% gray, and white, respectively. The differences in configuration between display modes are shown below.
(1)1-bpp (2-gray-level) mode
Use the first two entries of the green look-up table. Select two pieces of data from the 16 gray levels, and write them to the respective entries. The data in entry 0 is output for pixel data "0", and the data in entry 1 is output for pixel data "1". For monochrome display, write 0x0 to entry 0 and 0xF to entry 1 before using the LCD panel.
| | | Index | Green look-up table | | | |
1-bit pixel data "0" | | | 0 | 4-bit grayscale data for pixel data "0" | | | 4-bit display data |
|
| | | | | |
"1" | | | 1 | 4-bit grayscale data for pixel data "1" | | | |
| | | |
| 2 | | | | |
| : | Unused | | | |
| 15 | | | | |
Figure 2.9 Look-up Table in 1-bpp (2-Gray-Level) Mode
Table 2.6 shows an example of the basic data setting.
Table 2.6 Example of Look-up-Table Settings in 1-bpp (2-Gray-Level) Mode
Index | R look-up table | G look-up table | B look-up table |
0 | 0 | 0 | 0 |
1 | 0 | 0xF | 0 |
2–15 | 0 | 0 | 0 |
(2)2-bpp (4-gray-level) mode
Use the first four entries of the green look-up table. Select four pieces of data from the 16 gray levels, and write them to the respective entries. The data in entry 0 is output for pixel data "00", and the data in entry 3 is output for pixel data "11".
| | | Index | Green look-up table | | | |
"00" | | | 0 | 4-bit grayscale data for pixel data "00" | | | |
| | | | |
2-bit pixel data "01" | | | 1 | 4-bit grayscale data for pixel data "01" | | | 4-bit display data |
|
| | | | | |
"10" | | | 2 | 4-bit grayscale data for pixel data "10" | | | |
| | | | |
"11" | | | 3 | 4-bit grayscale data for pixel data "11" | | | |
| | | | |
| | | 4 | | | | |
| | | : | Unused | | | |
| | | 15 | | | | |
Figure 2.10 Look-up Table in 2-bpp (4-Gray-Level) Mode
Table 2.7 shows an example of the basic data setting.
Table 2.7 Example of Look-up-Table Settings in 2-bpp (4-Gray-Level) Mode
Index | R look-up table | G look-up table | B look-up table |
0 | 0 | 0 | 0 |
1 | 0 | 5 | 0 |
2 | 0 | 0xA | 0 |
3 | 0 | 0xF | 0 |
4–15 | 0 | 0 | 0 |
