HD66781 Datasheet, PDF (142/196 Pages) Renesas Technology Corp – 720-channel Source Driver for a-Si TFT/Low Temperature Poly-Si TFT Panels with 262,144-color display RAM

HD66781
Preliminary
Moving picture display in RGB Interface
The HD66781 incorporates the RGB interface to display moving pictures and RAM to store display data,
which provides the following merits in displaying moving pictures.
• The window address function enables the transfer of only data for the moving picture area.
• The high-speed write modes enables high-speed access to RAM with low power consumption
• Only transfer data that are written over the moving picture area.
• Reduced transmission contributes to the reduction of power consumption of the entire system.
• In combination with the system interface, the still picture area, such as an icon, can be updated
while displaying moving pictures.
RAM access through the system interface in RGB-I/F mode
RAM is accessible through the system interface in the RGB-I/F mode. In the RGB interface mode, data are
being written to RAM in synchronization with the DOTCLK input while the ENABLE is “Low”. When
writing data to RAM through the system interface, it is necessary to set ENABLE to “High” to stop data
write through the RGB-I/F. Setting RM = 0 allows RAM access through the system interface. When
reverting to the RGB interface mode, wait a write/read bus cycle. Then, set RM = 1 and the index to R202h
to start RAM access though the RGB-I/F. When RAM write through the RGB and system interfaces
conflicts, it is not guaranteed that the data are properly written to RAM.
The following is an example of moving picture display through the RGB-I/F and updating still picture area
through the system interface.
VSYNC
ENABLE
Screen update
Screen update
DOTCLK
PD17-0
Note 4)
Note 4)
System
interface
In dex
R202
Index Address
R202 Set
Moving picture
area Update
Data update in the area
other than moving picture
area
Still picture
area update
Address _{RM= 1 Index}
Set
R202
Moving picture
area Update
Not e 1) An address set is made every falling edge of VSYNC in the RGB interface mode.
N ot e 2) An address set and an index set (R202h) must be made before RAM access through the RGB interface.
N ot e 3) Write data in the high-speed write mode (HWM = 1) in the RGB interface mode.
Note 4) When transferring to a system interface mode, wait at least 1 write cycle (tcycw) after writing through the RGB interface.
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Mov i ng
picture area
Mov i ng
picture area
Updating still picture area during moving picture display
Rev.0.5, July.31.2003, page 142 of 196