GC9203
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supplied signals, VSYNC, HSYNC, and DOTCLK. In RGB interface mode, data (DB17-0)
are written in synchronization with these signals according to the polarity of enable signal
(ENABLE) to prevent flicker on display while updating display data. In VSYNC interface
mode, the display operation is synchronized with the internal clock except frame
synchronization, where the operation is synchronized with the VSYNC signal. Display data
are written to the internal GRAM via the system interface. In this case, there are constraints
in speed and method in writing data to the internal RAM. For details, see the “External
Display Interface” section. The GC9203 allows for switching between the external display
interface and the system interface by instruction so that the optimum interface is selected for
the kind of picture to be displayed on the screen (still and/or moving picture(s)). The RGB
interface, by writing all display data to the internal RAM, allows for transferring data only
when updating the frames of a moving picture, contributing to low power requirement for
moving picture display.
Address Counter (AC)
The address counter (AC) gives an address to the internal GRAM. When the index of the
register for setting a RAM address in the AC is written to the IR, the address information is
sent from the IR to the AC. As writing data into the internal GRAM, the address in the AC is
automatically updated plus or minus 1. The window address function enables writing data
only in the rectangular area arbitrarily set by users on the GRAM.
Graphics RAM (GRAM)
GRAM is graphics RAM storing bit-pattern data of 87,120 (176 x 220x 18/8) bytes, using 18
bits for each pixel.
Grayscale Voltage Generating Circuit
The grayscale voltage generating circuit generates a liquid crystal drive voltage according to
grayscale data set in the γ-correction register to display in 262,144 colors. For details, see the
“γ-Correction Register” section.
Timing Controller
The timing generator generates a timing signal for operation of internal circuits such as the
internal GRAM. The timing for the display operation such as RAM read operation and the
timing for the internal operation such as access from the MPU are generated in the way not
to interfere each other.
Oscillator (OSC.)
The GC9203 can provide R-C oscillation without external resistor. The appropriate
oscillation frequency for operating voltage, display size, and frame frequency can be