UPD78F9234MC-5A4-A Datasheet, PDF (57/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 4 PORT FUNCTIONS
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.
WRPU
RD
Figure 4-2. Block Diagram of P00 to P03
PU0
PU00 to PU03
VDD
P-ch
WRPORT
WRPM
P0
Output latch
(P00 to P03)
PM0
PM00 to PM03
PU0: Pull-up resistor option register 0
P0: Port register 0
PM0: Port mode register 0
RD: Read signal
WR××: Write signal
P00 to P03
User’s Manual U17446EJ5V0UD
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