CHAPTER 3 PIN FUNCTION (µPD78070A)
3.2.3 P20 to P27 (Port 2)
These are 8-bit input/output ports. Besides serving as input/output ports, they function as data input/output to/
from the serial interface, clock input/output, automatic transmit/receive busy input, and strobe output.
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 2 (PM2). When they are used as input ports, on-chip pull-up resistors can be connected
to them by defining the pull-up resistor option register L (PUOL).
(2) Control mode
These ports function as serial interface data input/output, clock input/output, automatic transmit/receive busy
input, and strobe output functions.
(a) SI0, SI1, SO0, SO1
Serial interface serial data input/output pins.
(b) SCK0, SCK1
Serial interface serial clock input/output pins.
(c) SB0, SB1
NEC standard serial bus interface input/output pins.
(d) BUSY
Serial interface automatic transmit/receive busy input pins.
(e) STB
Serial interface automatic transmit/receive strobe output pins.
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 Figure 17-4. Serial
Operation Mode Register 0 Format and Figure 19-3. Serial Operation Mode Register
1 Format.
60
ETC [ ETC ]
