871
SAM4CP [DATASHEET]
43051E–ATPL–08/14
39.
Segment Liquid Crystal Display Controller (SLCDC)
39.1
Description
The Segment Liquid Crystal Display Controller (SLCDC) can drive a monochrome passive liquid crystal display (LCD)
with up to 5 common terminals and up to 46 segment terminals.
An LCD consists of several segments (pixels or complete symbols) which can be visible or invisible. A segment has two
electrodes with liquid crystal between them. When a voltage above a threshold voltage is applied across the liquid
crystal, the segment becomes visible.
The voltage must alternate to avoid an electrophoresis effect in the liquid crystal, which degrades the display. Hence the
waveform across a segment must not have a DC component.
The SLCDC is programmable to support many different requirements such as:
Adjusting the driving time of the LCD pads in order to save power and increase the controllability of the DC offset.
Driving smaller LCD (down to 1 common by 1 segment).
Adjusting the SLCDC frequency in order to obtain the best compromise between frequency and consumption and
adapt it to the LCD driver.
Assigning the segments in a user defined pattern to use of the digital functions multiplexed on these pins.
Note: Please check SLCDC available signals in the main Block Diagram
Figure 2-1
.
39.1.1 Definition of Terms.
39.2
Embedded Characteristics
The SLCDC provides the following capabilities:
Display Capacity: Up to 46 Segments and 5 Common Terminals.
Support from Static to 1/6 Duty.
Support Static, 1/2, 1/3 Bias.
Two LCD Supply Sources:
Internal (On-chip LCD Power Supply).
External.
LCD Output Voltage Software Selectable from 2.4V to VDDIN in 16 Steps.
(Control Embedded in the Supply Controller).
Flexible Selection of Frame Frequency.
Two Interrupt Sources: End Of Frame and Disable.
Versatile Display Modes.
Equal Source and Sink Capability to Maximize LCD Life Time.
Segment and Common Pins not Needed for Driving the Display Can be Used as Ordinary I/O Pins.
Segments Layout can be Fully Defined by User to Optimize Usage of Multiplexed Digital Functions.
Latching of Display Data Gives Full Freedom in Register Updates.
Power Saving Modes for Extremely Low Power Consumption.
Register Write Protection
Table 39-1.
List of Terms
Term
Description
LCD
A passive display panel with terminals leading directly to a segment.
Segment
The least viewing element (pixel) which can be on or off.
Common(s)
Denotes how many segments are connected to a segment terminal.
Duty
1/(Number of common terminals on an actual LCD display).
Bias
1/(Number of voltage levels used driving a LCD display -1).
Frame Rate
Number of times the LCD segments are energized per second.