SAM4L Datasheet, PDF (1030/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
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
”Operating Modes” on page 1030).
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
offset
19
DATA[39:0]
15
DATA[39:0]
10
9
8
7
DATA[39:0]
6
5
4
3
2
DATA[39:0]
1
0
76543210
COM3
COM2
COM1
COM0
39.6.2
Operating Modes
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.
Table 39-2. Duty Selection
DUTY[1:0]
Duty
00
1/4
01
Static
10
1/2
11
1/3
Bias
1/3
Static
1/3
1/3
COM pins Used
COM[0:3]
COM0
COM[0:1]
COM[0:2]
39.6.2.1
Static Duty and Static Bias
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.
42023C–SAM–02/2013
1030