Atmel SAM4L-EK Atmel ATSAM4L-EK ATSAM4L-EK Data Sheet

42023E–SAM–07/2013

Addressing COM0 starts a frame by driving an opposite phase with large amplitude on COM0 as
against non addressed COM terminals. Non-energized segments are in phase with the
addressed COM0, and energized segments have opposite phase and large amplitude (refer to

).

Shadow display memory bits are multiplexed into the decoder. The decoder is configured by the
LCD timing and controls the analog switches to produce an output waveform onto each selected
COM terminals (duty value).

Figure 39-3. Display Memory Mapping

To energize a segment, an absolute voltage above the LCD threshold must be applied. This is
done by setting the SEG terminal to opposite phase when the corresponding COM terminal is
active. For a display with more than one common terminal, two additional voltage levels (1/3
bias) must be applied. Otherwise, non-energized segments on COM0 would be energized for all
non-selected common lines.

Duty bits (DUTY) in the Configuration register (CFG) defines the duty cycle. Unused common
terminals are driven to ground.

If all segments on a LCD have one common electrode then each segment have a unique seg-
ment terminal. SEG0-COM0 is the voltage across a segment that is ON and SEG1-COM0 is the
voltage across a segment that is OFF.

COM0

COM1

COM2

COM3

offset

0

1

2

3

4

5

6

7

8

9

15

19

DATA[39:0]

DATA[39:0]

DATA[39:0]

10

0

7

1

2

3

4

5

6

DATA[39:0]

Duty Selection

0 0

1/4

1/3

COM[0:3]

0 1

Static

Static

COM0

1 0

1/2

1/3

COM[0:1]

1 1

1/3

1/3

COM[0:2]