HD66724 Datasheet, PDF (81/117 Pages) Hitachi Semiconductor – (Graphics LCD Controller/Driver with Key Scan Function)

HD66724/HD66725
Vertical Smooth Scroll
The HD66724/HD66725 can scroll vertically in units of raster-rows. In character display mode (GR = 0),
this is achieved by writing character codes into a DDRAM area that is not being used for display. In other
words, since DDRAM corresponds to a 5-line × 16-character display, two lines can be used to achieve
continuous smooth vertical scroll even in a 3-line display. Here, after the fifth line is displayed, the first line
is displayed again. In the graphics display mode (GR = 1), a 96 x 32-dot area is assigned as CGRAM. Thus
a non-display area other than the 72 x 24-dot display area can be used to provide consecutive, smooth scroll
display. Segment (mark) display is system-fixed and the scroll function cannot be used.
Specifically, this function is controlled by incrementing or decrementing the value in the display-start line
bits (SL2 to SL0) and display-start raster-row bits (SN2/1/0) by 1. For example, to smoothly scroll up, first
set line bits SN2 to SN0 to 000, and increment SL2 to SL0 by 1 from 000 to 111 to scroll seven raster-
rows. Then increment line bits SN2 to SN0 to 001, and again increment SL2 to SL0 by 1 from 000 to 111.
To start displaying and scrolling from the first raster-row of the second line, update the first line of
DDRAM or CGRAM data as desired during its non-display period.
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