P90 To P97 (Port 9); Com0 To Com3; Lcd; Av Ref - NEC mPD780973 Series Preliminary User's Manual

2.2.9 P90 to P97 (Port 9)

These pins constitute an 8-bit input/output port. In addition, they also function to output segment signals from the
internal LCD controller/driver.
The following operating modes can be specified bit-wise.
(1) Port mode
In this mode, P90 to P97 function as an 8-bit input/output port. They can be set bit-wise in the input or output
mode by using port mode register 9 (PM9).
(2) Control mode
In this mode, P90 to P97 function as segment signal output pins (S5 to S12) of the LCD controller/driver.

2.2.10 COM0 to COM3

These pins output common signals from the internal LCD controller/driver during 4-time division drive in 1/3 bias
mode (COM0 to COM3 outputs).
2.2.11 V

LCD

This pin supplies a voltage to drive an LCD.
2.2.12 AV
REF
This is an A/D converter reference voltage input pin. This pin also functions as an analog power supply pin. Supply
power to this pin when the A/D converter is used.
When A/D converter is not used, connect this pin to V
2.2.13 AV
SS
This is a ground voltage pin of A/D converter. Always use the same voltage as that of the V
A/D converter is not used.

2.2.14 RESET

This is a low-level active system reset input pin.

2.2.15 X1 and X2

Crystal resonator connect pins for main system clock oscillation. When using an external clock supply, input it
to X1 and its inverted signal to X2.

2.2.16 SMV

DD
This pin supplies a positive power to the meter controller/driver.
2.2.17 SMV
SS
This is the ground pin of the meter controller/driver.
2.2.18 V
DD
Positive power supply port pin.
2.2.19 V
SS
Ground potential port pin.
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CHAPTER 2 PIN FUNCTION
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SS
pin even when an
SS