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CHAPTER 4 PORT FUNCTIONS
User’s Manual U15104EJ2V0UD
4.2.8 Port 12
Port 12 is a 6-bit I/O port with an output latch. Input or output mode can be specified for port 12 in 1-bit units using
port mode register 12 (PM12).
Alternate functions include serial interface data I/O and clock I/O.
Reset input sets port 12 to the input mode.
Figures 4-16 to 4-18 show the block diagrams of port 12.
Figure 4-16. Block Diagram of P120 and P123
PM: Port mode register
RD: Port 12 read signal
WR: Port 12 write signal
P120/SI32
P123/SI321
RD
WR
PORT
WR
PM
Alternate function
Output latch
(P120, P123)
PM120, PM123
Selector
Internal bus
Содержание mPD178053
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