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S1C63558 TECHNICAL MANUAL EPSON 53
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (LCD Driver)
4.7.6 LCD contrast adjustment
In the S1C63558, the LCD contrast can be adjusted by the software.
It is realized by controlling the voltages V
C1, VC23, VC4 and VC5 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.
The contrast can be adjusted to 16 levels as shown in Table 4.7.6.1.
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
Setting the LC3–LC0 register affects the VC23 voltage, and other voltages change according to the VC23. As
a result, the LCD contrast is adjusted.
The supply voltage V
DD within the range from 2.2 to 2.5 V affects the VC23 voltage. Ordinarily, VC23 is 2.4
V (when V
DD = 2.5 to 5.5 V) in the highest-contrast setting (No. 15 in Table 4.7.6.1), note, however, that
V
C23 will be VDD - 0.1 V when VDD = 2.2 to 2.5 V.
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.