CHAPTER 13 LCD CONTROLLER/DRIVER
13.7 Display Modes
13.7.1 Three-time slot display example
Figure 13-9 shows how the 5-digit LCD panel having the display pattern shown in Figure 13-8 is connected to the
segment signals (S0 to S14) and the common signals (COM0 to COM2) of the µPD789446 or µPD789456 Subseries
chip. This example displays data “123.45” in the LCD panel. The contents of the display data memory (addresses
FA00H to FA0EH) correspond to this display.
The following description focuses on numeral “3.” ( .) displayed in the third digit. To display “3.” in the LCD
panel, it is necessary to apply the select or deselect voltage to the S6 to S8 pins according to Table 13-6 at the
timing of the common signals COM0 to COM2.
Table 13-6. Select and Deselect Voltages (COM0 to COM2)
Segment
S6
S7
S8
Common
COM0
Select
Select
Select
Select
Select
Select
Deselect
Deselect
−
COM1
COM2
According to Table 13-6, it is determined that the display data memory location (FA06H) that corresponds to S6
must contain x111.
Figure 13-10 shows examples of LCD drive waveforms between the S6 signal and each common signal. When
the select voltage is applied to S6 at the timing of COM1 or COM2, an alternate rectangle waveform, +VLCD/–VLCD, is
generated to turn on the corresponding LCD segment.
Figure 13-8. Three-Time Slot LCD Display Pattern and Electrode Connections
COM0
S3n+1
S3n+2
S
3n
COM1
COM2
Remark n = 0 to 4
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User’s Manual U15075EJ1V0UM00
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