Renesas R5S72641 User Manual
Section 14 Realtime Clock
Page 700 of 2108
R01UH0134EJ0400 Rev. 4.00
Sep
24,
2014
SH7262 Group, SH7264 Group
Bit Bit
Name
Initial
Value R/W
Value R/W
Description
16 to 0
RFC[16:0]
Undefined R/W
Frequency comparison value
Sets the comparison value to generate operation clock
from the EXTAL clock frequency.
from the EXTAL clock frequency.
(1) Method for calculating "frequency comparison value".
1-Mbyte version
EXTAL clock frequency is dividable by 128-Hz
RFC[16:0]
(EXTAL clock frequency) / 128 2
Note: EXTAL clock frequency must be less than 16.778 MHz in the 1-Mbyte version.
640-Kbyte version
EXTAL clock frequency is dividable by 128-Hz
RFC[18:0]
(EXTAL clock frequency) / 128 2
Clear the SEL64 bit to 0 in this case.
EXTAL clock frequency is dividable by 64-Hz and not dividable by 128-Hz
RFC[18:0]
(EXTAL clock frequency) / 64 2
Set the SEL64 bit to 1 in this case.
(2) Setting Example
Table 14.3 Setting Example
EXTAL Clock
Frequency
Frequency
1-Mbyte Version
640-Kbyte Version
RFC Setting Value
SEL64 Setting Value
RFC Setting Value
10 MHz
H'1312B
0
H'1312B
12 MHz
H'16E34
0
H'16E34
15 MHz
No setting possible
1
H'39385
16 MHz
H'1E846
0
H'1E846