NEC uPD78P078 - Manual (Page 94)

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CHAPTER 4 PIN FUNCTION (
µ
PD78078Y SUBSERIES)
4.2.13 P130 and P131 (Port 13)
These are 2-bit input/output ports. Besides serving as input/output ports, they are used for D/A converter analog
output.
The following operating modes can be specified bit-wise.
(1) Port mode
These ports function as 2-bit input/output ports. They can be specified bit-wise as input or output ports with
port mode register 13 (PM13). When they are used as input ports, on-chip pull-up resistors can be connected
by defining the pull-up resistor option register H (PUOH).
(2) Control mode
These ports allow D/A converter analog output (ANO0 and ANO1).
Caution When only either one of the D/A converter channels is used with AV REF1 < V DD , the other pins
that are not used as analog outputs must be set as follows:
• Set PM13x bit of the port mode register 13 (PM13) to 1 (input mode) and connect the pin
to V SS .
• Set PM13x bit of the port mode register 13 (PM13) to 0 (output mode) and the output latch
to 0, to output low level from the pin.
4.2.14 AV REF0
A/D converter reference voltage input pin.
When A/D converter is not used, connect this pin to V SS .
4.2.15 AV REF1
D/A converter reference voltage input pin.
When D/A converter is not used, connect this pin to V DD .
4.2.16 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.
4.2.17 AV SS
This is a ground voltage pin of A/D converter and D/A converter. Always use the same voltage as that of the V SS
pin even when A/D converter or D/A converter is not used.
4.2.18 RESET
This is a low-level active system reset input pin.
4.2.19 X1 and X2
Crystal resonator connect pins for main system clock oscillation. For external clock supply, input it to X1 and its
inverted signal to X2.
4.2.20 XT1 and XT2
Crystal resonator connect pins for subsystem clock oscillation.
For external clock supply, input it to XT1 and its inverted signal to XT2.