UPD78F9234MC-5A4-A Datasheet, PDF (58/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 4 PORT FUNCTIONS
4.2.2 Port 2
Port 2 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 2 (PM2). When the P20 to P23 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 2 (PU2).
This port is also used as the analog input pins of the internal A/D converter.
Generation of reset signal sets port 2 to the input mode.
Figure 4-2 shows the block diagram of port 2.
WRPU
WRPMC
RD
Figure 4-3. Block Diagram of P20 to P23
PU2
PU20 to PU23
PMC2
PMC20 to PMC23
VDD
P-ch
WRPORT
WRPM
P2
Output latch
(P20 to P23)
PM2
PM20 to PM23
A/D converter
PU2: Pull-up resistor option register 2
P2: Port register 2
PM2: Port mode register 2
PMC2: Port mode control register 2
RD: Read signal
WR××: Write signal
P20/ANI0 to P23/ANI3
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User’s Manual U17446EJ5V0UD