
S1C8F360 TECHNICAL MANUAL
EPSON
105
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (LCD Controller)
5.12 LCD Controller
5.12.1 Configuration of LCD controller
The S1C8F360 has a built-in dot matrix LCD driver.
The S1C8F360 allows an LCD panel with a maxi-
mum of 1,632 dots (51 segments
× 32 commons). It
also has an LCD controller for an external LCD
driver.
Figure 5.12.1.1 shows the configuration of the LCD
controller and the drive power supply.
Note: It is necessary to connect a load resistance
between terminals VSS–VC1.
5.12.2 Mask option
The S1C8F360 generates the LCD drive voltage
using the internal power supply circuit. There is no
mask option for selecting an external power supply.
5.12.3 Switching drive duty
The S1C8F360 supports three types of LCD drive
duty settings, 1/8, 1/16 and 1/32, and it can be
switched using the LDUTY and DUTY8 registers.
When "0" is written to the drive duty selection
register LDUTY, 1/32 duty is selected and when "1"
is written, 1/16 duty is selected.
When "1" is written to DUTY8, the drive duty is
fixed at 1/8 and setting of LDUTY becomes invalid.
5.12.4 LCD power supply
The LCD system drive voltages VC1–VC5 are
generated by the internal voltage regulator and
voltage booster circuits. The internal power supply
can generate two types of reference voltage; TYPE
A (4.5 V) and TYPE B (5.5 V), and either one can be
selected according to the panel characteristics using
the LCDAJ register.
5.12.5 LCD driver
The maximum number of dots changes according
to the drive duty selection.
When 1/32 duty is selected, the combined com-
mon/segment output terminal is switched to the
common terminal. An LCD panel with 51 segments
× 32 commons (maximum 1,632 dots) can be driven
in the S1C8F360. When 1/16 duty is selected, the
combined common/segment output terminal is
switched to the segment terminal. An LCD panel
with 67 segments
× 16 commons (maximum 1,072
dots) in the S1C8F360 can be driven. When 1/8
duty is selected, the combined common/segment
output terminal is switched to the segment terminal
as when 1/16 duty is selected. An LCD panel with
67 segments
× 8 commons (maximum 536 dots) in
the S1C8F360 can be driven. Furthermore, when 1/
8 duty is selected, terminals COM8–COM15
become invalid, in that they always output an OFF
signal.
Table 5.12.5.1 shows the correspondence between
the drive duty and the maximum number of
displaying dots. The drive bias is 1/5 (five poten-
tials, VC1–VC5) for any one of the 1/32, 1/16 and 1/
8 duties. The respective drive waveforms are
shown in Figures 5.12.5.1–5.12.5.3.
CL (R25)
FR (R26)
VC1
VC2
VC3
VC4
VC5
CA
CB
CC
CD
CE
LCD system
voltage booster
VSS
LCD system
voltage regulater
Output port
R25, R26
LCD synchronous
signal generator
CL
FR
LCD contrast
adjustment circuit
LCCLK
LCFRM
LC3
LC2
LC1
LC0
LCD driver
DTFNT
VC3–VC5
LCDC1
LCDC0
LDUTY
Display memory
DSPAR
VC1,
VC2
COM0–COM15
COM16–COM31/SEG66–SEG51
SEG0–SEG50
LCDAJ
DUTY8
0
1
LDUTY
0
1
×
Duty
1/32
1/16
1/8
Common
terminal
COM0–COM31
COM0–COM15
COM0–COM7
Segment
terminal
SEG0–SEG50
SEG0–SEG66
Maximum number
of display dots
1,632 dots
1,072 dots
536 dots
Fig. 5.12.1.1
Configuration of LCD controller and
drive power supply
Table 5.12.5.1 Correspondence between drive duty and maximum number of displaying dots
Note: Do not use VC1–VC5 for driving the
expanded LCD driver.