NEC uPD78056Y - Manual (Page 141)

141
CHAPTER 6 PORT FUNCTIONS
P-ch
WR
PM
WR PORT
RD
WR
PUO
V DD
Selector
PUO3
Output Latch
(P30 to P37)
PM30-PM37
Internal bus
Alternate Function
P30/TO0
P32/TO2,
P33/TI1,
P34/TI2,
P35/PCL,
P36/BUZ,
P37
6.2.5 Port 3
Port 3 is an 8-bit input/output port with output latch. P30 to P37 pins can specify the input mode/output mode in
1-bit units with the port mode register 3 (PM3). When P30 to P37 pins are used as input ports, an on-chip pull-up
resistor can be used to them in 8-bit units with a pull-up resistor option register L (PUOL).
Alternate functions include timer input/output, clock output and buzzer output.
RESET input sets port 3 to input mode.
Figure 6-9 shows a block diagram of port 3.
Figure 6-9. P30 to P37 Block Diagram
PUO : Pull-up resistor option register
PM : Port mode register
RD : Port 3 read signal
WR : Port 3 write signal