hd66731a01tb0l Renesas Electronics Corporation., hd66731a01tb0l Datasheet - Page 99

• Manufacturer Part Number: hd66731a01tb0l
• Description: Dot-matrix Liquid Crystal Display Controller/driver Supporting Japanese Kanji, Korean Font Display - Hitachi Semiconductor
• Manufacturer: Renesas Electronics Corporation.

HD66730/HD66731
Vertical Smooth Scroll
Vertical smooth scroll up and down can be performed by setting the number of display lines (NL1/0: R4) to
a value greater than the actual number of liquid crystal display lines, which can be set by the duty drive
ratio (DT1/0: R1) to 1/14 (1-line display), 1/27 (2-line display), 1/40 (3-line display), or 1/53 (4-line
display). The display line setting (NL1/0: R4), which controls the display, can select 1-line display mode,
2-line display mode, or 4-line display mode.
For example, to perform normal vertical smooth scroll for a 3-line liquid crystal display with a duty ratio of
1/40, set the number of display lines (NL1/0: R4) to 4 lines. Note that if vertical smooth scroll is performed
when the number of actual liquid display lines is the same as the number of set display lines, the display
line that has scrolled out of the display will appear again from the bottom (or the top) (this function is
called lap-around). In a 4-line crystal liquid display, only the lap-around function can be performed.
Vertical smooth scroll is controlled by incrementing or decrementing the display line (SN1/0), which
indicates which line to start from, and the display raster-row (SL0 to SL3). For example, when performing
smooth scroll up, the display raster-row (SL0 to SL3) is incremented from 0000 to 1100 in order to scroll
12 raster-rows. Moreover, by incrementing the display line (SN1/0) and then incrementing the display
raster-row from 0000 to 1100 again, a total of 25 raster-rows can be scrolled. Since the DDRAM is only 80
bytes, its data must be rewritten when performing continuous scroll exceeding this capacity.
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