HD404356 Datasheet, PDF (68/100 Pages) Hitachi Semiconductor – 4-bit HMCS400-Series microcomputer

HD404358 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
Refer to
table 28
Output System clock —
Input External clock —
Figure 55 Serial Mode Register (SMR)
Port Mode Register C (PMRC: $025): This register has the following functions (figure 56).
• Prescaler division ratio selection
• Output level control in idle states
Port mode register C (PMRC: $025) is a 4-bit write-only register. It cannot be written during data transfer.
By setting bit 0 (PMRC0) of this register, the prescaler division ratio is selected. Bit 0 (PMRC0) can be
reset to 0 by MCU reset. By setting bit 1 (PMRC1), the output level of the SO pin is controlled in idle
states. The output level changes at the same time that PMRC1 is written to.
68