Rainbow Electronics Atmega169L - Manual (Page 213)

213
ATmega169V/L
2514A–AVR–08/02
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 100. SEG0 - COM0 is the voltage across a segment that is
on and SEG0-COM1 is the voltage across a segment that is off.
Figure 100. 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 101. SEG0 - COM0 is the voltage across a segment that is on and
SEG0 - COM1 is the voltage across a segment that is off.
Figure 101. 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