HD6473887 Datasheet, PDF (170/523 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

2. Port control register 4 (PCR4)
Bit
7
6
5
4
3
2
1
0
—
—
—
—
— PCR4₂ PCR4₁ PCR4 ₀
Initial value
1
1
1
1
1
0
0
0
Read/Write
—
—
—
—
—
W
W
W
PCR4 is an 8-bit register for controlling whether each of port 4 pins P4₂ to P4₀ functions as an
input pin or output pin. Setting a PCR4 bit to 1 makes the corresponding pin an output pin, while
clearing the bit to 0 makes the pin an input pin. PCR4 and PDR4 settings are valid when the
corresponding pins are designated for general-purpose input/output by SCR3-2.
Upon reset, PCR4 is initialized to H'F8.
PCR4 is a write-only register, which always reads all 1s.
8.5.3 Pin Functions
Table 8-12 shows the port 4 pin functions.
Table 8-12 Port 4 Pin Functions
Pin
P4₃/IRQ₀
P4₂/TXD₃₂
P4₁/RXD₃₂
Pin Functions and Selection Method
The pin function depends on bit IRQ0 in PMR3.
IRQ0
Pin function
0
P4₃ input pin
1
IRQ₀ input pin
The pin function depends on bit TE in SCR3-2, bit SPC32 in SPCR, and bit
PCR4₂ in PCR4.
SPC32
0
1
TE
0
1
PCR4₂
Pin function
0
P4₂ input pin
1
P4₂ output pin
*
TXD₃₂ output pin
The pin function depends on bit RE in SCR3-2 and bit PCR41 in PCR4.
RE
PCR4₁
Pin function
0
0
1
P4₁ input pin P4₁ output pin
1
*
RXD₃₂ input pin
*: Don’t care
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