I-120
EPSON
S1C88348/317/316/308 TECHNICAL HARDWARE
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (LCD Controller)
Fig. 5.12.4.3
Drive waveform for 1/8 duty
5.12.5 Display memory
The S1C883xx has a built-in 402-byte display
memory. The display memory is allocated to
address Fx00H–Fx42H (x = 8–DH) and the corre-
spondence between the memory bits and common/
segment terminal is changed according to the
selection status of the following items.
(1) Drive duty (1/32, 1/16 or 1/8 duty)
(2) Dot font (5
× 8 or 5 × 5 dots)
When 1/16 or 1/8 duty is selected for drive duty,
two-screen memory can be secured, and the two
screens can be switched by the display memory
area selection register DSPAR. When "0" is written
to DSPAR, display area 0 is selected and when "1" is
written, display area 1 is selected.
Furthermore, memory allocation for 5
× 8 dots and 5
× 5 dots can be selected in order to easily display 5 x
5-dot font characters on the LCD panel. This selection
can be done by the dot font selection register DTFNT:
when "0" is written to DTFNT, 5
× 8 dots is selected
and when "1" is written, 5
× 5 dots is selected.
The correspondence between the display memory
bits set according to the drive duty and font size,
and the common/segment terminals are shown in
Figures 5.12.5.1–5.12.5.6.
When "1" is written to the display memory bit
corresponding to the dot on the LCD panel, the dot
goes ON and when "0" is written, it goes OFF. Since
display memory is designed to permit reading/
writing, it can be controlled in bit units by logical
operation instructions and other means (read,
modify and write instruction)s.
The display area bits which have not been assigned
within the 402-byte display memory can be used as
general purpose RAM with read/write capabilities.
Even when external memory has expanded into the
display memory area, this area is not released to
external memory. Access to this area is always via
display memory.
COM0
1
2
3
4
5
6
7
SEG0
1
2
3
4
VDD
VSS
VC5
VC4
VC3
VC2
VC1
VSS
7
3
2
1
0
7
3
2
1
0
FR
COM0
COM1
COM2
SEG0
SEG1
VC5
VC4
VC3
VC2
VC1
VSS
VC5
VC4
VC3
VC2
VC1
VSS
VC5
VC4
VC3
VC2
VC1
VSS
VC5
VC4
VC3
VC2
VC1
VSS
VC5
VC4
VC3
VC2
VC1
V
(GND)
SS
VC5
VC4
VC3
VC2
VC1
V
(GND)
SS
COM0–SEG0
COM0–SEG1
4
6
4
6
55
-VC1
-VC2
-VC3
-VC4
-VC5
-VC1
-VC2
-VC3
-VC4
-VC5
64 Hz