UPD78F0411GA-GAM-AX Datasheet, PDF (405/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 15 LCD CONTROLLER/DRIVER
15.7.4 Four-time-slice display example
Figure 15-21 shows how the 12-digit LCD panel having the display pattern shown in Figure 15-20 is connected to
the segment signals (SEG0 to SEG21) and the common signals (COM0 to COM3) of the 78K0/LC3 chip. This
example displays data "23456.789012" 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 seventh digit. To display "6." in the LCD
panel, it is necessary to apply the select or deselect voltage to the SEG12 and SEG13 pins according to Table 15-8 at
the timing of the common signals COM0 to COM3; see Figure 15-20 for the relationship between the segment signals
and LCD segments.
Table 15-8. Select and Deselect Voltages (COM0 to COM3)
Segment
Common
COM0
COM1
COM2
COM3
SEG12
Select
Deselect
Select
Select
SEG13
Select
Select
Select
Select
According to Table 15-8, it is determined that the display data memory location (FA4CH) that corresponds to
SEG12 must contain 1101.
Figure 15-22 shows examples of LCD drive waveforms between the SEG12 signal and each common signal.
When the select voltage is applied to SEG12 at the timing of COM0, an alternate rectangle waveform, +VLCD/−VLCD, is
generated to turn on the corresponding LCD segment.
Figure 15-20. Four-Time-Slice LCD Display Pattern and Electrode Connections
SEG2n
SEG2n+1
Remark n = 0 to 10
COM0
COM2
COM1
COM3
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