LCD Controller Registers
11-29
LCD Controller
LCD TFT (LCDTFT)
The LCD TFT (LCDTFT) bit selects whether the LCD controller operates in
passive (STN) or active (TFT) display control mode. When LCDTFT = 0:
passive or STN mode is selected; all LCD data flow operates normally
(including the use of the LCD dither logic); and all LCD controller pin timing
operates as described in Section 11.7, LCD Controller Pins. When LCDTFT
= 1, active or TFT mode is selected. Frame data is transferred via the DMA
from off-chip memory to the input FIFO, is unpacked, and is used to select an
entry from the palette (for 1, 2, 4, and 8 bits-per-pixel modes), just as for
passive mode (see Figure 11–11).
Figure 11–11.Passive Mode Pixel Clock and Data Pin Timing
Data Pins
Change
LCD.PCLK
LCD.P [3:0]
LCD.HS
LCD.VS
Pixel 0
through 3
Pixel 4
through 7
Pixel 8
through 11
Pixel 12
through 15
Data Pins Samples
by the Display
LCDTFT=0
M8B=0
IPC=0
The value read from the palette, however, bypasses the LCD dither logic and
is sent directly to the output FIFO to be output on the LCD data pins. In TFT
mode, the pixel size within the frame buffer is increased to 16 bits when 12-
or 16-bit pixel encoding mode is enabled (BPP = 1XX). Thus, two 16-bit values
are packed into each word in the frame buffer. See Figure 11–12.