HD66750 Datasheet, PDF (68/96 Pages) Hitachi Semiconductor – 128 x 128-dot Graphics LCD Controller/Driver with Four-grayscale Functions

HD66750/1
Vertical Smooth Scroll Display
The HD66750/1 can scroll the graphics display vertically in units of raster-rows. The data storage capacity
of the CGRAM is 128 raster-rows. Continuous smooth vertical scrolling is achieved by writing display data
into a raster-row area that is not being used for display. After the 128th raster-row is displayed, the first
raster-row is displayed again. Using the status read, the user can check the display raster-rows (L6-0) that
are currently driving the LCD, and flicker can be eliminated by writing the display data in the CGRAM
while the LCD is not driven.
Additionally, when display areas of a graphics icon such as a pictogram or a menu bar are partially fixed-
displayed, the remaining areas can be displayed. For details, see the Partial Smooth Scroll Display Function
section.
Specifically, this function is controlled by incrementing or decrementing the value in the display-start
raster-row bits (SL6-0) by 1. For example, to smoothly scroll up, increment display-start raster-row bits
(SL6-0) by 1 from 0000000 to 1111111 to scroll 128 raster-rows.
Note that the vertical double-height display or window cursor display is not automatically changed in
synchronization with the vertical scrolling.
When the response speed of the liquid crystal is low or when high-speed scrolling is needed, two- to four-
raster-row scrolling is recommended.
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