User Manual

9-8 EP7309/11/12 User’s Manual - DS508UM4
Copyright Cirrus Logic, Inc. 2003
LCD Interface
9
GSEN[30]: Gray scale enable bit. Enables gray scale output to the LCD.
When cleared, each bit in the video map directly corresponds to a
pixel in the display.
GSMD[31]: Gray scale mode bit. Clearing this bit sets the controller to 2 bpp
(4-gray scale). Setting this bits enables 4 bpp (16-gray scale).
LCD Palette Registers
Least Significant Word (PALLSW)
Address: 0x8000.0580, Read / Write
Most Significant Word (PALMSW)
Address: 0x8000.0540, Read / Write
Bit Descriptions:
The least and most significant word of th e LCD palette registers
(read/write) map the p ixel value s tored i n the frame buffer to a
physical gray s cale level. The two 32-bit registers define all gray
scale levels for a total of 4 bpp. If 2 bpp is required, only the p alette
least significant word need be programmed. At 1 bpp, only the first
two nibbles in the least significant register are required to be
programmed.
Table 9-2 on page 9-8 represents th e mapping of the p ixel value from memory to the
gray scale value programmed into the registers.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Gray scale value for pixel value 7 Gray scale value for pixel value 6 Gray scale value for pixel value 5 Gray scale value for pixel value 4
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Gray scale value for pixel value 4 Gray scale value for pixel value 3 Gray scale value for pixel value 2 Gray scale value for pixel value 1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Gray scale value for pixel value 15 Gray scale value for pixel value 14 Gray scale value for pixel value 13 Gray scale value for pixel value 12
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Gray scale value for pixel value 11 Gray scale value for pixel value 10 Gray scale value for pixel value 9 Gray scale value for pixel value 8