HD404054 Datasheet, PDF (74/103 Pages) Hitachi Semiconductor – HMCS400-series microcomputers designed to increase program productivity with large-capacity memory

HD404054 Series/HD404094 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
Prescaler
SM1A2 SM1A1 SM1A0 SCK₁ Clock source division ratio
0
0
0
Output Prescaler
Refer to
table 26
1
1
0
1
1
0
0
1
1
0
Output System clock —
1
Input External clock —
Figure 53 Serial Mode Register 1A (SM1A)
Serial Mode Register 1B (SM1B: $028): This register has the following functions (figure 54).
• Serial interface 1 prescaler division ratio selection
• Serial interface 1 output level control in idle states
Serial mode register 1B (SM1B: $028) 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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