NEC PD78214 - Manual (Page 95)

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µ
PD78214 Sub-Series
Fig. 5-9 Connection of Pull-Up Resistors (Port 2)
Caution P22 through P26 are not pulled up immediately after a reset. In this case, INTP1 through INTP5 (one of the multiple functions
assigned to P22 to P26) may set interrupt request flags. To avoid this problem, specify use of the pull-up resistors in the initialization
routine, before clearing the interrupt flags.
5.4 PORT 3
Port 3 is an 8-bit I/O port with an output latch. The port 3 mode register (PM3) can put each bit of this port in either
the input or output mode, separately from the other bits. Each pin has a software-programmable built-in pull-up
resistor.
In addition to I/O functions, each pin works as control signal pin.
The port 3 mode control register (PMC3) can specify the mode of operation for each pin separately from the other
pins, as listed in Table 5-4. The level of any pin can be read and tested, regardless of what function the pin is
performing.
When the RESET signal is input, port 3 becomes an input port (in the high output impedance state), and the
contents of the output latch become undefined.
Internal bus
V
DD
P22
P23
P24
P25
P26
P27
PUO2
Pull-up resistor option register (PUO)
Input buffer