CHAPTER 4 PORT FUNCTIONS
Preliminary User’s Manual U16315EJ1V0UD
91
4.2.4 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 used as an input port, use of an on-chip pull-up resistor can be specified by
pull-up resistor option register 3 (PU3).
This port can also be used for external interrupt request input.
RESET input sets port 3 to input mode.
Figures 4-12 and 4-13 show block diagrams of port 3.
Figure 4-12. Block Diagram of P30 to P32
P30/INTP1 to
P32/INTP3
WR
PU
RD
WR
PORT
WR
PM
PU30 to PU32
Alternate
function
Output latch
(P30 to P32)
PM30 to PM32
EV
DD
P-ch
Selector
Internal bus
PU3:
Pull-up resistor option register 3
PM:
Port mode register
RD:
Port 3 read signal
WR:
Port 3 write signal
Содержание 78K0/KD1 Series
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