NEC 78K0 Series User Manual page 114

5.2.4 Port 3
Port 3 is a 4-bit I/O port with an output latch. Port 3 can be set to the input mode or output mode in 1-bit units
using port mode register 3 (PM3). When the P30 to P33 pins are used as an input port, use of an on-chip pull-up
resistor can be specified in 1-bit units by pull-up resistor option register 3 (PU3).
This port can also be used for external interrupt request input and timer I/O.
Reset signal generation sets port 3 to input mode.
Figures 5-14 and 5-15 show block diagrams of port 3.
µ
Caution In the PD78F0537D, be sure to pull the P31 pin down before a reset release to prevent
malfunction.
Remark The P31 and P32 pins of the
OCD1B) when the on-chip debug function is used. For details, see CHAPTER 27 ON-CHIP DEBUG
µ
FUNCTION (
114
CHAPTER 5 PORT FUNCTIONS
µ
PD78F0537D can be used as on-chip debug mode setting pins (OCD1A,
PD78F0537D ONLY).
Figure 5-14. Block Diagram of P30 to P32
Preliminary User's Manual U17260EJ3V1UD