811
LCD Controller/Driver (LCD-C/D)
Chapter 22
Preliminary User’s Manual U17566EE1V2UM00
22.1.2
LCD panel addressing
Each individual segment
of an LCD panel is addressed by a signal pair: a
segment signal and a common signal. The segment becomes visible when the
potential difference of the corresponding common signal and the segment
signal reaches or exceeds the LCD drive voltage V
LCD
.
Example
Figure 22-2
shows how the eight LCD segments of a digit are allocated to
• two segment signals (SEG
2n
and SEG
2n+1,
n = 0 to 19)
• four common signals
Figure 22-2
Allocation of segment signals and common signals to LCD segments
(4-time-division)
Every combination of a segment and a common signal addresses a single
element. The middle horizontal bar, for example, becomes visible if the
potential difference of signals SEG
2n+1
and COM1 exceeds V
LCD
.
To display a desired pattern on the LCD panel:
1. Check what combination of segment and common signals form the desired
display pattern.
2. Write bit data with the pattern to be displayed to registers SEGREGk.
The LCD Controller/Driver generates the corresponding segment and common
signals.
See also the
“Display Example“ on page 818
.
Connections
At the LCD panel, the signals are connected as follows:
Caution
The LCD panel is driven by AC voltage. The performance of the LCD
deteriorates if DC voltage is applied in the common and segment signals. That
means contrast and brightness of the display may decrease. The display may
even be damaged.
COM0
SEG
2n
COM1
SEG
2n + 1
COM2
COM3
Table 22-2
Signals and connections of LCD Controller/Driver
Signals
Connection at LCD panel
segment signals
front surface electrodes
common signals
rear surface electrodes
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