46
EPSON
S1C63454 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (LCD Driver)
When a bit in the display memory is set to "1", the corresponding LCD dot goes ON, and when it is set to
"0", the dot goes OFF.
At 1/17 (1/16) duty drive, all data of COM0–COM16 (15) is output.
At 1/8 duty drive, data only corresponding to COM0–COM7 is output. However, since the display
memory has capacity for two screens, it is designed so that the memory for COM8–COM15 shown in
Figure 4.7.5.1 (b) can also be used as COM0–COM7. Select either F000H–F04FH or F100H–F14FH for the
area to be displayed (to be output from COM0–COM7 terminals) using the LPAGE register. It can switch
the screen in an instant.
At initial reset, the data memory content becomes undefined hence, there is need to initialize using the
software.
The display memory has read/write capability, and the addresses that have not been used for LCD
display can be used as general purpose registers.
Note: When a program that access no memory mounted area (F050H–F0FFH, F150H–F1FFH, F201H,
F203H, · · ·, F24FH) is made, the operation is not guaranteed.
4.7.6 LCD contrast adjustment
In the S1C63454, the LCD contrast can be adjusted by the software.
It is realized by controlling the voltages V
C1
, V
C2
, V
C4
and V
C5
output from the LCD system voltage
circuit. When these voltages are supplied to the externally expanded LCD driver, the expanded LCD
contrast is adjusted at the same time. However, when the LCD drive voltage is supplied from outside by
the mask option selection, this adjustment becomes invalid.
The contrast can be adjusted to 16 levels as shown in Table 4.7.6.1. When VCCHG = "0", V
C1
is changed
within the range from 0.975 V to 1.2 V, and other voltages change according to V
C1
. When VCCHG = "1",
V
C2
is changed within the range from 1.950 V to 2.4 V, and other voltages change according to V
C2
.
Table 4.7.6.1 LCD contrast
No.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
LC3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
LC2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
LC1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
LC0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Contrast
light
dark
At room temperature, use setting number 7 or 8 as standard.
Since the contents of LC0–LC3 are undefined at initial reset, initialize it by the software.
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