NEC PD78F9488 - Manual (Page 260)

CHAPTER 13 LCD CONTROLLER/DRIVER
260
User’s Manual U15331EJ4V1UD
13.7 Display Modes
13.7.1 Three-time-slice display example
Figure 13-10 shows how a nine-digit LCD panel having the display pattern shown in Figure 13-9 is connected to
the segment signals (S0 to S26) and the common signals (COM0 to COM2) of the µPD789489 Subseries chip. This
example displays the data "123456.789" in the LCD panel. The contents of the display data memory (addresses
FA00H to FA1AH) correspond to this display.
The following description focuses on numeral "6." ( ) displayed as the fourth digit from the right. To display "6." in
the LCD panel, it is necessary to apply the select or deselect voltage to the S9 to S11 pins according to Table 13-5 at
the timing of the common signals COM0 to COM2; see Figure 13-9 for the relationship between the segment signals
and LCD segments.
Table 13-5. Select and Deselect Voltages (COM0 to COM2)
Segment S9 S10 S11
Common
COM0 Deselect Select Select
COM1 Select Select Select
COM2 Select Select −
According to Table 13-5, it is determined that the display data memory location (FA09H) that corresponds to S9
must contain x110.
Figure 13-11 shows an example of LCD drive waveforms between the S9 signal and each common signal. When
the select voltage is applied to S9 at the timing of COM1 or COM2, an alternate rectangle waveform, +V
LCD
/-V
LCD
, is
generated to turn on the corresponding LCD segment.
Figure 13-9. Three-Time-Slice LCD Display Pattern and Electrode Connections
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S 3n+2 S 3n
COM0
COM2
S 3n+1
COM1
Remark n = 0 to 8