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CHAPTER 12 APPLICATIONS OF LCD CONTROLLER/DRIVER
12.1 Static Display
This section explains an example using the
μ
PD78064 subseries. A 4-digit static LCD is driven by using the 32
segment signals (S0 through S31) and a common signal (COM0). Figure 12-7 shows the display pattern and electrode
wiring of the static LCD. Figure 12-8 shows the connections among the segment signals and common signal. Figure
12-9 shows an example of connecting an LCD driving power supply in the static display mode (with an external divider
resistor, V
DD
= 5 V, and V
LCD
= 5 V). The display example in Figure 12-8 is “1234”, and the contents of the display
data memory (addresses FA60H through FA7FH) correspond to this.
In this section, how to display the second digit, “3”, is described. According to the display pattern in Figure 12-
8, the select and unselect voltages must be output to the S8 through S15 pins in the timing of the common signal
COM0, as shown in Table 12-3.
Table 12-3. Select and Unselect Voltages (COM0)
Segment
Common
S8
S9
S10
S11
S12
S13
S14
S15
COM0
Unselect
Select
Select
Select
Unselect
Select
Unselect
Select
From Table 12-3, it is clear that 10101110 must be set to bit 0 of the display data memory (addresses FA70H through
FA77H) corresponding to S8 through S15.
Figure 12-10 shows the LCD driving waveforms of S11, S12, and COM0.
Because the same waveform as COM0 is output to COM1, 2, and 3, the driving capability can be increased by
connecting COM0, 1, 2, and 3.
Figure 12-7. Display Pattern and Electrode Wiring of Static LCD
Remark
n = 0-3
S8
n
+ 2
S8
n
+ 1
COM0
S8
n
+ 5
S8
n
S8
n
+ 7
S8
n
+ 3
S8
n
+ 4
S8
n
+ 6