Datasheet

1032
42023E–SAM–07/2013
ATSAM4L8/L4/L2
39. LCD Controller (LCDCA)
Rev: 1.0.0.0
39.1 Features
• Display capacity up to 40 segment and up to 4 common terminals
• Supports from static up to 1/4 duty
• Supports static and 1/3 bias
• Shadow display memory gives full freedom in segment update
• ASCII character mapping
• Automated characters string scrolling
• Automated characters string display
• Automated segments display
• Autonomous animation up to 8 segments
• LCD driver active in power save mode for low power operation
• Low power waveform
• Flexible selection of frame frequency
• Configurable blink mode and frequency
• Uses only 32 kHz clock
• On-chip LCD power supply
• Software contrast adjustment control
• Equal source and sink capability to increase LCD life time
• Interrupt mode for display update or wake-up from sleep mode
39.2 Overview
A LCD display is made of several segments (or complete symbols) which can be visible or invis-
ible. A segment has two electrodes with liquid crystal between them. These electrodes are the
common terminal (COM) and the segment terminal (SEG). When a voltage above a threshold
voltage is applied across the liquid crystal, the segment becomes visible. The voltage must alter-
nate to avoid an electrophoresis effect in the liquid crystal, this effect degrades the display.
Hence the voltage waveform across a segment must not have a DC-component.
Figure 39-1. LCD Segment/Common Terminals
The LCD controller (LCDCA) is intended for monochrome passive liquid crystal display (LCD)
with up to 4 common terminals and up to 40 segment terminals. Unused segment/common ter-
minals (pins) are configured as general purpose I/O pins.The LCD controller uses a 32kHz clock
(CLK_LCD) and can therefore be running in deep sleep modes.
s
egm
e
nt
0
se
gm
en
t
1
s
egment
2
seg
me
nt
4
2
s
egme
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t
41
se
gm
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40
COM0
COM1
SEG0 SEG1 SEG2
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