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CHAPTER 17 LCD CONTROLLER/DRIVER
User
’
s Manual U14701EJ3V0UD
17.8.2 3-time-division display example
Figure 17-16 shows the connection of a 3-time-division type 13-digit LCD panel with the display pattern shown
in Figure 17-15 with the
μ
PD780338 Subseries segment signals (S0 to S38) and common signals (COM0 to COM2).
The display example is
“
123456.7890123,
”
and the display data memory contents (addresses FA00H to FA26H)
correspond to this.
An explanation is given here taking the example of the eighth digit
“
6.
”
(
in Figure 17-15, selection and non-selection voltages must be output to pins S21 to S23 as shown in Table 17-9 at
the COM0 to COM2 common signal timings.
). In accordance with the display pattern
Table 17-9. Selection and Non-Selection Voltages (COM0 to COM2)
Segment
S21
S22
S23
Common
COM0
NS
S
S
COM1
S
S
S
COM2
S
S
—
S: Selection, NS: Non-selection
From this, it can be seen that
×
110 must be prepared in the display data memory (address FA15H) corresponding
to S21.
Examples of the LCD drive waveforms between S21 and the common signals are shown in Figure 17-17 (1/3 bias
method). When S21 is at the selection voltage at the COM1 selection timing, and S21 is at the selection voltage at
the COM2 selection timing, it can be seen that the +V
LCD
/
–
V
LCD
AC square wave, which is the LCD illumination (ON)
level, is generated.
Figure 17-15. 3-Time-Division LCD Display Pattern and Electrode Connections
Remark
n = 0 to 12
S
3n + 2
S
3n
COM0
COM2
S
3n + 1
COM1