Rainbow Electronics ATmega3290P_V - Manual (Page 224)

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ATmega329/3290/649/6490
2552H–AVR–11/06
1/3 Duty and 1/3 Bias 1/3 bias is usually recommended for LCD with three common terminals (1/3 duty).
Waveform is shown in Figure 102. SEG0 - COM0 is the voltage across a segment that is
on and SEG0-COM1 is the voltage across a segment that is off.
Figure 102. Driving a LCD with Three Common Terminals
1/4 Duty and 1/3 Bias 1/3 bias is optimal for LCD displays with four common terminals (1/4 duty). Waveform is
shown in Figure 103. SEG0 - COM0 is the voltage across a segment that is on and
SEG0 - COM1 is the voltage across a segment that is off.
Figure 103. Driving a LCD with Four Common Terminals
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
- 1 /
3
V
LCD
- 2 /
3
V
LCD
-V
LCD
SEG0
COM0
SEG0 - COM0
Frame Frame
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
- 1 /
3
V
LCD
- 2 /
3
V
LCD
-V
LCD
SEG0
COM1
SEG0 - COM1
Frame Frame
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
- 1 /
3
V
LCD
- 2 /
3
V
LCD
-V
LCD
SEG0
COM0
SEG0 - COM0
Frame Frame
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
V
LCD
2 /
3
V
LCD
1 /
3
V
LCD
GND
- 1 /
3
V
LCD
- 2 /
3
V
LCD
-V
LCD
SEG0
COM1
SEG0 - COM1
Frame Frame