NEC uPD78056Y - Manual (Page 66)

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CHAPTER 3 PIN FUNCTION (
µ
PD78054 Subseries)
(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 16-4 “Serial
Operation Mode Register 0 Format” and Figure 18-3 “Serial Operation Mode Register
1 Format.”
3.2.4 P30 to P37 (Port 3)
These are 8-bit input/output ports. Beside serving as input/output ports, they function as timer input/output, clock
output and buzzer output.
The following operating modes can be specified in 1-bit units.
(1) Port mode
These ports function as 8-bit input/output ports. They can be specified in 1-bit units as input or output ports
with port mode register 3 (PM3). When they are used as input ports, on-chip pull-up resistors can be used
by defining the pull-up resistor option register L (PUOL).
(2) Control mode
These ports function as timer input/output, clock output, and buzzer output.
(a) TI1 and TI2
Pin for external count clock input to the 8-bit timer/event counter.
(b) TO0 to TO2
Timer output pins.
(c) PCL
Clock output pin.
(d) BUZ
Buzzer output pin.