ATMEGA169P-15AT Datasheet, PDF (236/373 Pages) ATMEL Corporation – 8-bit Microcontroller with 16K Bytes In-System Programmable Flash

22.3.3
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 22-5. SEG0 - COM0 is the voltage across a segment that is on and SEG0-
COM1 is the voltage across a segment that is off.
Figure 22-5. Driving a LCD with Three Common Terminals
V_LCD
2_/3VLCD
1_/3VLCD
GND
SEG0
V_LCD
2_/3VLCD
1_/3VLCD
GND
SEG0
V_LCD
2_/3VLCD
1_/3VLCD
GND
COM0
V_LCD
2_/3VLCD
1_/3VLCD
GND
COM1
V_LCD
2_/3VLCD
1_/3VLCD
GND
-¹/₃V_LCD
-²/₃V_LCD
-V_LCD
Frame
Frame
SEG0 - COM0
V_LCD
2_/3VLCD
1_/3VLCD
GND
-¹/₃V_LCD
-²/₃V_LCD
-V_LCD
Frame
SEG0 - COM1
Frame
22.3.4
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 22-6. SEG0 - COM0 is the voltage across a segment that is on and SEG0 - COM1 is
the voltage across a segment that is off.
Figure 22-6. Driving a LCD with Four Common Terminals
V_LCD
2_/3VLCD
1_/3VLCD
GND
SEG0
V_LCD
2_/3VLCD
1_/3VLCD
GND
V_LCD
2_/3VLCD
1_/3VLCD
GND
COM0
V_LCD
2_/3VLCD
1_/3VLCD
GND
V_LCD
2_/3VLCD
1_/3VLCD
GND
-¹/₃V_LCD
-²/₃V_LCD
-V_LCD
Frame
Frame
SEG0 - COM0
V_LCD
2_/3VLCD
1_/3VLCD
GND
-¹/₃V_LCD
-²/₃V_LCD
-V_LCD
Frame
SEG0
COM1
SEG0 - COM1
Frame
236 ATmega169P Automotive
7735B–AVR–12/07