Intel PXA26X - Manual (Page 294)

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-/dual-panel select (SDS) bit selects the type of display control
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 LCD controller drivers have two line/row shifters
(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 used.
DMA channel 0 is used to load the palette RAM from the frame buffer and to drive the upper half
of the display, and DMA channel 1 drives the lower half. The two channels alternate when fetching
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 doubles 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. Figure 7-18 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]