NEC 78014Y Series, User Manual

Page: 72 / 547

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CHAPTER 3 PIN FUNCTION (
µ
PD78014 Subseries)
72
3.2.7 P60 to P67 (Port 6)
These are 8-bit output dedicated ports. Besides serving as input/output port, they have control functions in external
memory expansion mode.
P60 to P63 can drive LEDs directly.
The following operating modes can be specified bit-wise.
(1) Port mode
These ports function as 8-bit input/output ports. They can be specified bit-wise for input or output ports by port
mode register 6 (PM6).
P60 to P63 are N-ch open-drain outputs. Mask ROM version can contain pull-up resistors with the mask option.
When P64 to P67 are used as input ports, an on-chip pull-up resistor can be connected with a pull-up resistor
option resistor (PUO).
(2) Control mode
These ports function as control signal output pins (RD, WR, WAIT, ASTB) in external memory expansion mode.
When a pin is used as control signal output, the on-chip pull-up resistor is automatically disabled.
Caution When external wait is not used in external memory expansion mode, P66 can be used as an input/
output port.
3.2.8 AV
REF
A/D converter reference voltage input pin.
When the A/D converter is not used, connect it to V
SS
.
3.2.9 AV
DD
Analog power supply pin of A/D converter.
Always use the same voltage as that of the V
DD
pin even when A/D converter is not used.
3.2.10 AV
SS
This is a ground voltage pin of A/D converter. Always use the same voltage as that of the V
SS
pin even when A/D
converter is not used.
3.2.11 RESET
This is a low-level active system reset input pin.
3.2.12 X1 and X2
Crystal resonator connection pins for main system clock oscillation.
For external clock supply, input it to X1 and its inverted signal to X2.