HD66781 Datasheet, PDF (86/196 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
RAM Access through RGB-I/F and System I/F
The HD66781 writes all display data to the internal RAM even in the RGB-I/F mode. Through the RGB-
I/F mode, only the data for the moving picture area as well as for the frames to update screens can be
transmitted. By writing data in the high-speed write mode (HWM = 1) and with the window address
function, the HD66781 achieves high-speed access to RAM with low power consumption while displaying
moving pictures. In the frames other than the moving picture screen update, the display data in the area
other than the moving picture area can be updated through a system interface.
RAM access is also possible through the system interface even in the RGB-I/F mode. In the RGB interface
mode, data are written to RAM in synchronization with the DOTCLK input during ENABLE = “Low”.
When writing data in the RGB-I/F mode through the system interface, it is necessary to set ENABLE
“High” to stop writing through the RGB interface. After accessing RAM through the system interface, wait
an enough time for the write/read bus cycle before starting RAM access through the RGB interface.
Screen update
Screen update
In dex
R22
Index Address
R202 Set
Data update in the area
other than moving picture
area
Updating
moving pict ur e area
Note 1) Updat ing
still pictur e area
Address _{RM= 1}
Set
Index
R202
Updating
moving pict ur e area
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.
6/25 00:00
6/25 00:00
Mov i ng
picture area
Mov i ng
picture area
Updating still picture area while displaying a moving picture
Rev.0.5, July.31.2003, page 86 of 196