Port 0 - NEC 78K0/KD1 Series User Manual

4.2.1 Port 0

Port 0 is a 4-bit I/O port with an output latch. Port 0 can be set to the input mode or output mode in 1-bit units
using port mode register 0 (PM0). When the P00 to P03 pins are used as an input port, use of an on-chip pull-up
resistor can be specified by pull-up resistor option register 0 (PU0).
This port can also be used for timer I/O.
RESET input sets port 0 to input mode.
Figures 4-2 to 4-4 show block diagrams of port 0.
WR
PU
RD
WR
PORT
WR
PM
PU0: Pull-up resistor option register 0
PM: Port mode register
RD: Port 0 read signal
WR: Port 0 write signal
CHAPTER 4 PORT FUNCTIONS
Figure 4-2. Block Diagram of P00 and P03
PU00, PU03
Alternate
function
Output latch
(P00, P03)
PM00, PM03
Preliminary User's Manual U16315EJ1V0UD
EV
DD
P-ch
P00/TI000,
P03
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