UPD78F9500MA-CAC-A Datasheet, PDF (68/342 Pages) Renesas Technology Corp – 8-Bit Single-Chip Microcontrollers

CHAPTER 4 PORT FUNCTIONS
4.2.3 Port 4
Port 4 is a 2-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 4 (PM4)^Note. When the P40 and P43 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 4 (PU4).
Reset signal generation sets port 4 to the input mode.
Figures 4-11 shows the block diagram of port 4.
Note In μPD78F920x, set PM41, PM42, and PM44 to PM47 to "0" at program initialization.
WRPU
RD
Figure 4-11. Block Diagram of P40 and P43
PU4
PU40, PU43
VDD
P-ch
WRPORT
WRPM
P4
Output latch
(P40, P43)
PM4
PM40, PM43
P4: Port register 4
PU4: Pull-up resistor option register 4
PM4: Port mode register 4
RD: Read signal
WR××: Write signal
4.3 Registers Controlling Port Functions
The ports are controlled by the following four types of registers.
• Port mode registers (PM2 to PM4)
• Port registers (P2 to P4)
<R> • Port mode control register 2 (PMC2) (μPD78F920x only)
• Pull-up resistor option registers (PU2 to PU4)
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User’s Manual U18172EJ3V0UD
P40, P43