CHAPTER 4 PORT FUNCTIONS
85
User’s Manual U11302EJ4V0UM
4.2.2 Port 1
Port 1 is an 8-bit I/O port with an output latch. The P10 to P17 pins can be set to input mode/output mode in
1-bit units using port mode register 1 (PM1). When the P10 to P17 pins are used as input port pins, on-chip pull-
up resistors can be connected to them in 8-bit units using the pull-up resistor option register (PUO).
Alternate functions include A/D converter analog input.
RESET input sets port 1 to input mode.
Figure 4-4 shows a block diagram of port 1.
Caution A pull-up resistor cannot be connected to pins used for A/D converter analog input.
Figure 4-4. Block Diagram of P10 to P17
PUO: Pull-up resistor option register
PM:
Port mode register
RD:
Port 1 read signal
WR:
Port 1 write signal
P-ch
WR
PM
WR
PORT
RD
WR
PUO
V
DD
P10/ANI0
to
P17/ANI7
Selector
PUO1
Output latch
(P10 to P17)
PM10 to PM17
Internal bus
