Rainbow Electronics Atmega169L - Manual (Page 212)

212
ATmega169V/L
2514A–AVR–08/02
Figure 98. Driving a LCD with One Common Terminal
1/2 Duty and 1/2 Bias For LCD with two common terminals (1/2 duty) a more complex waveform must be used
to individually control segments. Although 1/3 bias can be selected 1/2 bias is most
common for these displays. Waveform is shown in Figure 99. SEG0 - COM0 is the volt-
age across a segment that is on, and SEG0 - COM1 is the voltage across a segment
that is off.
Figure 99. Driving a LCD with Two Common Terminals
V
LCD
GND
V
LCD
GND
V
LCD
GND
-V
LCD
SEG0
COM0
SEG0 - COM0
Frame Frame
V
LCD
GND
V
LCD
GND
GND
SEG1
COM0
SEG1 - COM0
Frame Frame
V
LCD
GND
V
LCD
1 /
2
V
LCD
GND
V
LCD
1 /
2
V
LCD
GND
-1 /
2
V
LCD
-V
LCD
SEG0
COM0
SEG0 - COM0
Frame Frame
V
LCD
GND
V
LCD
1 /
2
V
LCD
GND
V
LCD
1 /
2
V
LCD
GND
-1 /
2
V
LCD
-V
LCD
SEG0
COM1
SEG0 - COM1
Frame Frame