UPD78F0411GA-GAM-AX Datasheet, PDF (401/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 15 LCD CONTROLLER/DRIVER
15.7.3 Three-time-slice display example
Figure 15-17 shows how the 8-digit LCD panel having the display pattern shown in Figure 15-16 is connected to
the segment signals (SEG0 to SEG22) and the common signals (COM0 to COM2) of the 78K0/LC3 chip. This
example displays data "23456.78" in the LCD panel. The contents of the display data memory (addresses FA40H to
FA55H) correspond to this display.
The following description focuses on numeral "6." ( ) displayed in the third digit. To display "6." in the LCD panel,
it is necessary to apply the select or deselect voltage to the SEG6 to SEG8 pins according to Table 15-7 at the timing
of the common signals COM0 to COM2; see Figure 15-16 for the relationship between the segment signals and LCD
segments.
Table 15-7. Select and Deselect Voltages (COM0 to COM2)
Segment
Common
COM0
COM1
COM2
SEG6
Deselect
Select
Select
SEG7
Select
Select
Select
SEG8
Select
Select
−
According to Table 15-7, it is determined that the display data memory location (FA46H) that corresponds to SEG6
must contain x110.
Figures 15-18 and 15-19 show examples of LCD drive waveforms between the SEG6 signal and each common
signal in the 1/2 and 1/3 bias methods, respectively. When the select voltage is applied to SEG6 at the timing of
COM1 or COM2, an alternate rectangle waveform, +VLCD/−VLCD, is generated to turn on the corresponding LCD
segment.
Figure 15-16. Three-Time-Slice LCD Display Pattern and Electrode Connections
SEG3n+1
COM0
SEG3n+2
SEG3n
COM1
Remark n = 0 to 6
COM2
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