HD404654 Datasheet, PDF (78/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404654 Series
Transmit clock
Serial output
data
1
2
3
4
5
6
7
8
LSB
MSB
Serial input data
latch timing
Figure 60 Serial Interface Output Timing
Port Mode Register A (PMRA: $004): This register has the following functions (figure 61).
• R4₂/SI₁ pin function selection
• R4₃/SO₁ pin function selection
Port mode register A is a 4-bit write-only register, and is reset to $0 by MCU reset.
Port mode register A (PMRA: $004)
Bit
Initial value
Read/Write
Bit name
3
2
1
0
—
—
0
0
—
—
W
W
Not used Not used PMRA1 PMRA0
PMRA0
0
1
R4₃/SO₁ mode selection
R4₃
SO₁
PMRA1
0
1
R4₂/SI₁ mode selection
R4₂
SI₁
Figure 61 Port Mode Register A (PMRA)
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