HD404629R Datasheet, PDF (93/157 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a DTMF Generator Circuit

HD404629R Series
Serial mode register A (SMRA: $005)
Bit
Initial value
Read/Write
Bit name
3
2
1
0
0
0
0
0
W
W
W
W
SMRA3 SMRA2 SMRA1 SMRA0
R2₁/SCK
SMRA3 _{mode selection}
0
R2₁
1
SCK
SMRA2 SMRA1 SMRA0 SCK
Prescaler
Clock source division ratio
0
0
0
Output Prescaler
Refer to
table 29
1
1
0
1
1
0
0
1
1
0
Output System clock —
1
Input External clock —
Figure 74 Serial Mode Register A (SMRA)
Serial Mode Register B (SMRB: $028): This register has the following functions (figure 75).
 Prescaler division ratio selection
 Output level control in idle states
Serial mode register B is a 2-bit write-only register. It cannot be written during data transfer.
By setting bit 0 (SMRB0) of this register, the prescaler division ratio is selected. Only bit 0 (SMRB0) can
be reset to 0 by MCU reset. By setting bit 1 (SMRB1), the output level of the SO pin is controlled in idle
states. The output level changes at the same time that SMRB1 is written to.
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