NEC uPD78P078 - Manual (Page 148)

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CHAPTER 6 PORT FUNCTIONS
6.2.9 Port 7
This is a 3-bit input/output port with output latches. Input mode/output mode can be specified in 1-bit units with
a port mode register 7 (PM7). When pins P70 to P72 are used as input port pins, an on-chip pull-up resistor can
be connected in 3-bit units with a pull-up resistor option register L (PUOL).
Dual-functions include serial interface channel 2 data input/output and clock input/output.
RESET input sets the input mode.
Port 7 block diagrams are shown in Figures 6-15 and 6-16.
Caution When used as a serial interface, set the input/output and output latch according to its functions.
For the setting method, refer to Table 20-2. Serial Interface Channel 2 Operating Mode Setting.
Figure 6-15. Block Diagram of P70
PUO : Pull-up resistor option register
PM : Port mode register
RD : Port 7 read signal
WR : Port 7 write signal
P-ch
WR PM
WR
PORT
RD
WR PUO
V DD
Selector
PUO7
Output Latch
(P70)
PM70
Internal bus
P70/SI2/RxD