HD66781 Datasheet, PDF (112/196 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
Interface specification
The HD66781 incorporates a system interface to make settings for instructions and an external display
interface to display moving pictures. The HD66781 allows selecting an optimum interface for display
(moving or still picture, or both) to transmit data efficiently.
The external display interface includes RGB interface and VSYNC interface, which enable flicker-free
screen update.
In the RGB-I/F mode, the display operation is performed in synchronization with the signals (VSYNC,
HSYNC, and DOTCLK). The display data are written according to the values of the data enable signal
(ENABLE), and PD17-0 bits in synchronization with the VSYNC, HSYNC, and DOTCLK signals. The
display data are written to GRAM to reduce the data transmission to minimum, i.e. only when the displays
are being changed. With the window address function, only the RAM area used for moving picture display
is overwritten, and therefore the simultaneous display of moving picture area, which is overwritten, and the
RAM data in the area other than the moving picture area, which is not overwritten, is possible. In the RGB
and VSYNC interface modes, write data to GRAM in the high speed write mode (HWM = 1) during
displaying moving pictures to access to GRAM in high speed with low power consumption.
In the VSYNC interface mode, the frame synchronization signal (VSYNC) synchronizes internal display
operations. By writing data in synchronization with the falling edge of VSYNC at a fixed speed to GRAM
through a system interface, moving pictures are displayed with the system interface in use. In this case,
there are some constraints in the speed and method to write data to RAM.
The HD66781 handles the following 4 operational modes according to the type of display. All settings are
made through the external display interface. Transition between the modes must be done according to the
transitional flow charts.
Table 62
Operation Mode
RAM Access Setting (RM) Display Operation Mode (DM1-0)
Internal operating clock only
(Displaying still picture)
System interface
(RM = 0)
Internal operating clock
(DM1-0 = 00)
RGB interface (1)
(Displaying moving picture)
RGB interface
(RM = 1)
RGB interface
(DM1-0 = 01)
RGB interface (2)
(Rewriting still picture while
displaying moving pictures)
System interface
(RM = 0)
RGB interface
(DM1-0 = 01)
VSYNC interface
(Displaying moving pictures)
System interface
(RM = 0)
VSYNC interface
(DM1-0 = 10)
Note 1) Instructions are set only through a system interface.
Note 2) RGB-I/F and VSYNC-I/F are not used simultaneously.
Note 3) Do not make a change to the RGB-I/F mode (RIM-0) while the RGB I/F is operating.
Note 4) When making transitions between the interfaces, see the “External Display Interface” (p.139) for the
transition flow chart
Note 5) RGB-I/F and VSYNC-I/F modes should be used with the high-speed write mode (HWM = 1).
Rev.0.5, July.31.2003, page 112 of 196