hd66789 Renesas Electronics Corporation., hd66789 Datasheet - Page 91

• Manufacturer Part Number: hd66789
• Description: 528-channel, One-chip Driver For Amorphous Tft Panels With 262,144-color Display Ram, Power Supply Circuit, And Gate Circuit
• Manufacturer: Renesas Electronics Corporation.

HD66789
Moving picture display
The HD66789 incorporates the RGB interface to display moving pictures and RAM to store display data,
which provides the following merits in displaying moving pictures.
RAM access through system interface in RGB-I/F mode
RAM is accessible through a 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 R22h
to start RAM access though the RGB-I/F. When the RAM writes through the RGB and system interface
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.
Rev.0.12, May 09 2003, page 91 of 156
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The window address function enables the transfer of only data for the moving picture area.
The high-speed write mode enables high-speed access to RAM with low power consumption
Only transmitting 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 a system interface, the still picture area, such as an icon, can be updated while
displaying moving pictures.
System interface
ENABLE
DOTCLK
Updating Still Picture Area during Displaying Moving Picture
VSYNC
PD17-0
Note 1) In the RGB interface mode, the address is set at every falling edge of VSYNC.
Note 2) Set the address and the index (R22h) before RAM access starts through the RGB interface mode.
Note 3) In the RGB interface mode write data in the high-speed write mode (HWM = 1).
Index set
Index
R22
Updating moving
picture area
Updating screen
RM=0
address
Setting
of
2001/01/01 00:00
Updating of still picture area
Index
R22
Moving picture area
Still picture area
other than moving
Updating of area
picture area
address
Setting
of
*Note 2
* Note 1
RM=1
Index
R22
Updating moving
picture area
Updating screen
Preliminary