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μ
PD17016, 17017
259
21.2 Functional Outline of LCD Controller/Driver
The LCD controller/driver can display up to 60 dots by using the combination of common signal output pins
(COM
1
and COM
0
) and segment signal output pins (LCD
29
/P0F
3
through LCD
0
/KS
0
).
Figure 21-2 shows the relation among common signal output pins, segment signal output pins, and display
dots.
As shown in this figure, two dots at the intersections between one segment line with COM
1
and COM
0
pins.
The driving mode is 1/2 duty, 1/2 bias, and the drive voltage is supply voltage V
DD
.
The segment signal output pins (LCD
29
/P0F
3
through LCD
22
/P0E
0
) pins can also be used as general-purpose
output port pins.
When these pins are used as general-purpose output port pins, ports 0F (LCD
29
/P0F
3
through LCD
26
/P0F
0
)
and 0E (LCD
25
/P0E
3
through LCD
22
/P0E
0
) can be independently used.
Of the segment signal output pins, the LCD
15
/KS
15
through LCD
0
/KS
0
pins are also used as key source signal
output pins.
The key source signals and LCD segment signals are output by means of time-division multiplexing.
For the details on the general-purpose output ports, refer to
15. GENERAL-PURPOSE PORT
.
For the details on the key source signals, refer to
22. KEY SOURCE CONTROLLER/DECODER
.
The following subsections 21.2.1 through 21.2.5 outlines the function of each block of the LCD controller/
driver.
Figure 21-2. Common Signal Output, Segment Signal Output, and Display Dot
21.2.1 LCD segment register
The LCD segment register sets dot data that is used to turn ON/OFF the LCD.
Because this register is mapped on the data memory, it can be controlled by any data memory manipulation
instruction.
When the segment signal output pins are used as general-purpose output port pins, this registers sets output
data.
For details, refer to
21.3
.
COM
1
pin
Display dot
Segment signal output pin (LCD
n
)
COM
0
pin