IPC = 0
Data pins samples
by the display
Data pins
change
LCD_PCLK
LCD_D[x:0]
LCD_HSYNC
LCD_VSYNC
Pixel 0
Pixel 1
Pixel 2
Pixel 3
1 LCD_CLK clock period
LCD_AC_ENB_CS
BIAS = 0
Registers
1061
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Liquid Crystal Display Controller (LCDC)
When TFT_STN = 1, active or TFT mode is selected. Video data is transferred via the DMA from memory
to the input FIFO, then is unpacked and used to select an entry from the palette (for 1, 2, 4, and 8 bits per
pixel modes), just as in passive mode. The value read from the palette; however, bypasses both the LCD
dither logic and 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). In
TFT mode for 12 and 16 bits per pixel, palette entry is not selected. The clock and data pin behaviors is
shown in
.
Figure 23-25. Active Mode Pixel Clock and Data Pin Timing
describes the clocks and data pin behaviors in active mode. The size of the pixel encoding is increased in
TFT mode because the LCD dither logic is bypassed (the dither logic only supports 4 bits to encode each
color component R, G, B that limits the pixel encoding size in passive mode). Increasing the size of the
pixel representation allows a total of 64K colors to be addressed using an off-chip palette in conjunction
with the LCD controller.
23.3.8.4
Mono 8 Bit Mode (MONO8B)
NOTE:
MONO8B does not affect any of the color modes or TFT.
The mono 8-bit mode (MONO8B) bit selects whether four or eight data lines are used to output pixel data
to the LCD screen.
•
When MONO8B = 0, pixel data [3:0] is used to output four pixel values to the LCD panel at each pixel
clock transition.
•
When MONO8B = 1, pixel data [7:0] is used to output eight pixel values to the LCD panel at each pixel
clock transition
23.3.8.5
FIFO DMA Request Delay (FIFO_DMA_DELAY)
The 8-bit FIFO DMA request delay (FIFO_DMA_DELAY) field is used to select the minimum number of
LCD_CLK cycles to wait between the servicing of each DMA request issued by the LCD controller,
sending an address to the input FIFO. The goal is to ensure enough bandwidth to other system accesses.
A delay of FIFO_DMA_DELAY cycles is inserted every 16 words read from the input FIFO. This function is
a concern only in 8 BPP mode, where the palette is 256 words. The FIFO_DMA_DELAY field needs to be
set properly to avoid FIFO underflow during palette loading phase. When FDD = 00h, the FIFO DMA
request delay function is disabled. This function is only used for palette loading.