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CHAPTER 4 PORT FUNCTIONS
User’s Manual U19780EJ2V0UD
104
4.2.7 Port 7
78K0/KB2-A 78K0/KC2-A
P70/KR0
P71/KR1
P72/KR2
P73/KR3
P74/KR4
−
P75/KR5
Port 7 is an I/O port with an output latch. Port 7 can be set to the input mode or output mode in 1-bit units using
port mode register 7 (PM7). When the P70 to P75 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 7 (PU7).
This port can also be used for key return input.
Reset signal generation sets port 7 to input mode.
Figure 4-17 shows a block diagram of port 7.
Figure 4-17. Block Diagram of P70 to P75
P70/KR0
to
P75/KR5
WR
PU
RD
WR
PORT
WR
PM
PU70 to PU75
PM70 to PM75
V
DD
P-ch
PU7
PM7
P7
Internal bus
Output latch
(P70 to P75)
Selector
Alternate
function
P7:
Port register 7
PU7:
Pull-up resistor option register 7
PM7:
Port mode register 7
RD: Read
signal
WR
××
: Write
signal