NEC uPD78P078 - Manual (Page 74)

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CHAPTER 3 PIN FUNCTION (
µ
PD78078 SUBSERIES)
3.2.8 P70 to P72 (Port 7)
This is a 3-bit input/output port. In addition to its use as an input/output port, it also has serial interface data input/
output and clock input/output functions.
The following operating modes can be specified bit-wise.
(1) Port mode
Port 7 functions as a 3-bit input/output port. Bit-wise specification as an input port or output port is possible
by means of port mode register 7 (PM7). When used as input ports, on-chip pull-up resistors can be
connected by defining the pull-up resistor option register L (PUOL).
(2) Control mode
Port 7 functions as serial interface data input/output and clock input/output.
(a) SI2, SO2
Serial interface serial data input/output pins
(b) SCK2
Serial interface serial clock input/output pin.
(c) RxD, TxD
Asynchronous serial interface serial data input/output pins.
(d) ASCK
Asynchronous serial interface serial clock input/output pin.
Caution When this port is used as a serial interface, the I/O and output latches must be set according
to the function the user requires.
For the setting, refer to the operation mode setting list in Table 20-2. Serial Interface
Channel 2.
3.2.9 P80 to P87 (Port 8)
These are 8-bit input/output ports. Besides serving as input/output ports, they function as an address bus.
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 as input or output ports with
port mode register 8 (PM8). 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 function as lower address bus pins (A0 to A7) in external memory expansion mode. When a
pin is used as an address bus, the on-chip pull-up resistor is automatically not used.