CHAPTER 4 PORT FUNCTIONS
User’s Manual U17446EJ3V1UD
52
4.2.1 Port
0
Port 0 is a 4-bit I/O port with an output latch. Each bit of this port can be set to the input or output mode by using
port mode register 0 (PM0). When the P00 to P03 pins are used as an input port, an on-chip pull-up resistor can be
connected in 1-bit units by using pull-up resistor option register 0 (PU0).
This port is also used as the analog input pins of the internal A/D converter.
Generation of reset signal sets port 0 to the input mode.
Figure 4-2 shows the block diagram of port 0.
Figure 4-2. Block Diagram of P00 to P03
P00 to P03
WR
PU
RD
WR
PORT
WR
PM
PU00 to PU03
Output latch
(P00 to P03)
PM00 to PM03
V
DD
P-ch
PM0
P0
PU0
Selector
Internal bus
PU0:
Pull-up resistor option register 0
P0:
Port register 0
PM0:
Port mode register 0
RD:
Read signal
WR
××
: Write signal
Содержание 78K0S/KB1+
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