
S1C88409 TECHNICAL MANUAL
EPSON
93
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (LCD Controller)
5.10.7 Vertical scroll function
Since the display start address is specified by the
SAD register, vertical scroll can be done by
increasing/decreasing the address by one line at a
step.
80
dots
80
lines
80
lines
240 dots
LCD panel (B&W)
A
A: SAD = 00F200H
B: SAD = 00F21EH
B
Display memory
F200H
F21EH
F21DH
F23BH
Line
1
2
3
FB42H
FB60H
FB5FH
FB7DH
80
81
82
Fig. 5.10.7.1 Vertical scroll
Note: When using the vertical scroll function, it is
necessary to reserve the display memory
for the scroll area in addition to the memory
for the LCD panel size.
Do not specify a display start address that
cannot entirely display one screen (as
exceeding the last display memory address
in the middle of the LCD panel).
5.10.8 Virtual screen function
In normal display, the beginning address of a line
follows the end address of the previous line. In
this LCD controller, the interval between the
addresses can be specified using the APADJ
register in byte units. This function can configure a
virtual screen larger than the actual display size as
shown in Figure 5.10.8.1. By controlling the
display start address with the SAD register, the
screen can be scrolled horizontally in byte units
(B&W: 8-dot units, gray-scale: 4-dot units) or any
part of the virtual screen can be displayed.
Furthermore, when a virtual screen with a two
page size is assigned, the page can simply be
switched.
Note: When using the virtual screen function,
enough display memory must be reserved
for the screen size.
Do not specify a display start address that
cannot entirely display one screen (as
exceeding the last display memory address
in the middle of the LCD panel).
100
dots
160 dots
LCD panel (B&W)
APADJ = 10H, SAD = 00F110H
SLT
=
64H
Display memory
LBC = 14H
F000H
F110H
F134H
F133H
F157H
F123H
F147H
FCA4H
FCC7H
FCB7H
APADJ = 10H, SAD = 00F111H
SLT
=
64H
Display memory
Display area
LBC = 14H
F000H
F111H
F135H
F134H
F158H
F124H
F148H
FCA5H
FCC8H
FCB8H
Fig. 5.10.8.1 Virtual screen function