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Chapter 22
LCD Controller/Driver (LCD-C/D)
Preliminary User’s Manual U17566EE1V2UM00
22.3.2
Activation of LCD segments
An LCD segment becomes visible when the potential difference of the
corresponding common signal and segment signal reaches or exceeds the
LCD drive voltage V
LCD
. This is achieved if common and segment signal are at
their selection levels.
Within one frame cycle T
F
, each LCD segment can be activated once.
Activation lasts for one duty cycle T. LCD segments corresponding to common
signals COM0 to COM3 are not activated simultaneously, but consecutively.
22.4 Display Example
As a display example, register contents and output signals for a 20-digit LCD
display are presented in this section.
(1)
LCD panel
The display pattern of a single digit is given below. Each digit is addressed by
two segment signals and four common signals.
Figure 22-6
4-time-division LCD pattern and electrode connections
Figure 22-7 on page 820
shows the whole LCD panel and its connection to the
segment signals and common signals. The display example is
“123456.78901234567890,” and the register contents of SEGREG0k (k = 0 to
39) correspond to this.
An explanation is given here taking the example of the 6th digit with point: “6.”.
The corresponding segment signals are output to pins SEG28 and SEG29 with
the selection levels at the COM0 to COM3 common signal timings as shown in
the table below:
COM0
SEG
2n
COM1
SEG
2n + 1
COM2
COM3
Table 22-8
Selection and non-selection levels of example
Common signal
Segment signal SEG28
Segment signal SEG29
COM0
selected
selected
COM1
not selected
selected
COM2
selected
selected
COM3
selected
selected
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