7-26 Intel® PXA26x Processor Family Developer’s Manual
Liquid Crystal Display Controller
7.6.1.12 Single-/Dual-Panel Select (SDS)
In passive mode (PAS=0), the single-/d ual-pa nel sel ect ( SDS) bi t select s the ty pe o f dis play con trol
implemented by the LCD screen. When SDS=0, single-panel operation is selected (pixels
presented to screen a line at a time). When SDS=1, dual-panel operation is selected ( pixels
presented to screen two lines at a time). Single-panel LCD drivers have one line/row shifter and
driver for pixels and one line pointer. Dual -panel L CD cont ro ller drive rs have two lin e/r ow shi fte rs
(one for the top half of the screen, one for the bottom) and two line pointers (one for the top half of
the screen, one for the bottom).
When dual-panel mode is programmed, both of the LCD controller’s DMA channels are us ed.
DMA channel 0 is used to load the palette RAM from the frame buffer and to drive the upper hal f
of the display, and DMA channel 1 drives the lower half . The two channels alter nate when fetchin g
data for both halves of the screen, placing encoded pixel values in the two separate input FIFOs.
When dual-panel operation is enabled, the LCD controller d oubles its pin usage. For monochrome
screens, eight pins are used and for color screens, 16 pins are used.
Note: SDS must be set to 0 in active mode (PAS=1).
Table 7 -3 shows the LCD data pins and GPIO pins used for each mode of operation and the
ordering of pixels delivered to a screen for each mode of operation.
Note: In passive color mode, the data pin ordering switches. Figure7-18 on page 7-27 shows the LCD
data pin pixel ordering.
.
† Double-pixel data mode (DPD) = 1.
Table 7-3. LCD Controller Data Pin Utilization
Color/Monochrome
Panel Single/
Dual Panel Passive/
Active Panel Screen Portion Pins
Monochrome Single Passive Whole L_DD[3:0]
Monochrome Single Passive Whole L_DD[7:0]
Monochrome Dual Passive Top L_DD[3:0]
Bottom L_DD[7:4]
Color Single Passive Whole L_DD[7:0]
Color Dual Passive Top L_DD[7:0]
Bottom L_DD[15:8]
Color Single Active Whole L_DD[15:0]