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NEC uPD78054(A) Manuale Utente

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CHAPTER 6   PORT FUNCTIONS
P-ch
WR
PM
WR
PORT
RD
WR
PUO
V
DD
Selector
PUO5
Output Latch
(P50 to P57)
PM50-PM57
Internal bus
P50/A8
P57/A15
6.2.7  Port 5
Port 5 is an 8-bit input/output port with output latch.  P50 to P57 pins can specify the input mode/output mode in
1-bit units with the port mode register 5 (PM5).  When P50 to P57 pins are used as input ports, an on-chip pull-up
resistor can be used to them in 8-bit units with a pull-up resistor option register L (PUOL).
Port 5 can drive LEDs directly.
Alternate function includes address bus function in external memory expansion mode.
RESET input sets port 5 to input mode.
Figure 6-12 shows a block diagram of port 5.
Figure 6-12.  P50 to P57 Block Diagram
PUO :  Pull-up resistor option register
PM
:  Port mode register
RD
:  Port 5 read signal
WR :  Port 5 write signal