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HD404654 Datasheet, PDF (76/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer
HD404654 Series
Serial mode register 1A (SM1A: $005)
Bit
Initial value
Read/Write
Bit name
3
0
W
SM1A3
2
0
W
SM1A2
1
0
W
SM1A1
0
0
W
SM1A0
SM1A3
0
1
R41/SCK1
mode selection
R41
SCK1
SM1A2
0
1
SM1A1 SM1A0
0
0
1
1
0
1
0
0
1
1
0
1
SCK1
Output
Output
Input
Prescaler
Clock source division ratio
Prescaler
Refer to
table 25
System clock —
External clock —
Figure 56 Serial Mode Register 1A (SM1A)
Serial Mode Register 1B (SM1B: $028): This register has the following functions (figure 57).
• Serial interface 1 prescaler division ratio selection
• Serial interface 1 output level control in idle states
Serial mode register 1B is a 2-bit write-only register. It cannot be written during data transfer.
By setting bit 0 (SM1B0) of this register, the serial interface 1 prescaler division ratio is selected. Only bit
0 (SM1B0) can be reset to 0 by MCU reset. By setting bit 1 (SM1B1), the output level of the SO1 pin is
controlled in idle states of serial interface 1. The output level changes at the same time that SM1B1 is
written to.
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