305
XMEGA B [DATASHEET]
8291B–AVR–01/2013
When a bit in the Display Memory is written to one, the corresponding segment will be energized (“ON”), and de-
energized (“OFF”) when this bit is written to zero.
To energize a segment, an absolute voltage above a certain threshold must be applied. This is done by setting the SEG
pin to opposite phase when the corresponding COM pin is active. For a display with more than one common terminal,
two (1/3 bias) additional voltage levels must be applied. Otherwise, non-energized segments on COM0 would be
energized for all non-selected common terminals.
Addressing COM0 starts a frame by driving an opposite phase with large amplitude on COM0 as against non addressed
COM lines. Non-energized segments are in phase with the addressed COM0, and energized segments have opposite
phase and large amplitude. For waveform figures refer to
“Mode of Operation” on page 306
.
DATA4 - DATA0 from Shadow Display Memory is multiplexed into the decoder. The decoder is controlled from the LCD
timing and sets up signals controlling the analog switches to produce an output waveform.
Next, COM1 is addressed, and DATA9 - DATA5 from Shadow Display Memory is input to the decoder. Addressing
continues until all COM lines are addressed according to the number of selected common terminals (duty).
25.2.5 Minimizing Power Consumption
The power consumption of the LCD controller can be minimized by:
1.
Using the lowest acceptable frame rate - Refer to the LCD glass technical characteristics.
2.
Using the low power waveform -
“Low Power Waveform” on page 307
3.
Programming the lowest possible contrast value -
“CTRLF – Control register F” on page 317.
25.3
Block Diagram
Figure 25-2. LCD Controller Block Diagram
COMy
V
LCD
BIAS
1
BIAS
2
CTRLF
Analog
Switch
Array
Shadow
Display
Memory
LCD Power
Supply
Control & Swap
Timing
CTRLD
CTRLC
CTRLA
CTRLB
Character
Mapping
CTRLH
CTRLG
CTRLE
CAPH CAPL
SEGx
INT
DATAn
DATA1
:
DATA0
Display
Memory
Summary of Contents for XMEGA B
Page 320: ...320 XMEGA B DATASHEET 8291B AVR 01 2013 Table 25 12 7 segments Character Table...
Page 321: ...321 XMEGA B DATASHEET 8291B AVR 01 2013 Table 25 13 14 segments Character Table...
Page 322: ...322 XMEGA B DATASHEET 8291B AVR 01 2013 Table 25 14 16 segments Character Table...
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