HD4074344 Datasheet, PDF (68/100 Pages) Hitachi Semiconductor – 4-bit microcomputers

HD404344R Series/HD404394 Series
Serial mode register (SMR: $005)
Bit
Initial value
Read/Write
Bit name
3
0
W
SMR3
2
0
W
SMR2
1
0
W
SMR1
0
0
W
SMR0
SMR3
0
1
R0₀/SCK
Mode Selection
R0₀
SCK
SMR2
0
1
SMR1
0
1
0
1
SMR0
0
1
0
1
0
1
0
1
SCK
Prescaler
Clock Source Division Ratio
Output Prescaler
See table 22.
Output System clock —
Input External clock —
Figure 45 Serial Mode Register (SMR)
Port Mode Register C (PMRC: $025): This register has the following functions:
• Prescaler division ratio selection
• Output level control during idle states
Port mode register C is a two-bit write-only register, which cannot be changed during data transfer.
Bit 0 (PMRC0) selects the prescaler division ratio. Only this bit is reset to 0 by an MCU reset.
Bit 1 enables the output level control of the SO pin during an idle state. The output levels at the pins are
therefore changed when writing to bit 1 (PMRC1).
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