HD404669 Datasheet, PDF (89/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
Transmit clock
Serial output
data
Serial input
data latch timing
1
2
3
4
5
6
7
8
LSB
MSB
Figure 66 Serial Interface Output Timing
Port Mode Register A (PMRA: $004): This register has the following functions (figure 67).
• R4₂/SI₁ pin function selection
• R4₃/SO₁ pin function selection
Port mode register A (PMRA: $004) is a 2-bit write-only register. It is reset to "--00" by an MCU reset or
when the MCU switches to stop mode.
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
PMRA1
0
1
R4₂/SI1 mode selection
R4₂
SI1
PMRA0
0
1
R4₃/SO1 mode selection
R4₃
SO₁
Figure 67 Port Mode Register A (PMRA)
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