HD404849 Datasheet, PDF (90/125 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404849 Series
Serial data register (upper digit) (SRU: $007)
Bit
Initial value
Read/Write
Bit name
3
2
1
0
Undefined Undefined Undefined Undefined
R/W
R/W
R/W
R/W
SR7
SR6
SR5
SR4
Figure 73 Serial Data Register (SRU)
Transmit clock
Serial output
data
1
2
3
4
5
6
7
8
LSB
MSB
Serial input data
latch timing
Figure 74 Serial Interface Input/Output Timing
Port Mode Register A (PMRA: $004): This register has the following functions (figure 75).
• R2₂/SI pin function selection
• R2₃/SO pin function selection
Port mode register A (PMRA: $004) is a 2-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
PMRA1
0
1
R2₂/SI mode selection
R2₂
SI
PMRA0
0
1
R2₃/SO mode selection
R2₃
SO
Figure 75 Port Mode Register A (PMRA)
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