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 VC1, 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.

LC3

LC2

LC1

LC0

 

Contrast

0

0

0

0

0

 

light

1

0

0

0

1

 

 

 

 

 

2

0

0

1

0

 

 

 

3

0

0

1

1

 

 

 

4

0

1

0

0

 

 

 

5

0

1

0

1

 

 

 

6

0

1

1

0

 

 

 

7

0

1

1

1

 

 

 

8

1

0

0

0

 

 

 

9

1

0

0

1

 

 

 

10

1

0

1

0

 

 

 

11

1

0

1

1

 

 

 

12

1

1

0

0

 

 

 

13

1

1

0

1

 

 

 

14

1

1

1

0

 

 

 

 

 

15

1

1

1

1

 

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 VDD within the range from 2.2 to 2.5 V affects the VC23 voltage. Ordinarily, VC23 is 2.4 V (when VDD = 2.5 to 5.5 V) in the highest-contrast setting (No. 15 in Table 4.7.6.1), note, however, that VC23 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.

S1C63558 TECHNICAL MANUAL

EPSON

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