RL78/G1P
CHAPTER 5 CLOCK GENERATOR
R01UH0895EJ0100 Rev.1.00
121
Nov 29, 2019
Table 5-3. CPU Clock Transition and SFR Register Setting Examples (2/3)
(3) CPU clock changing from high-speed on-chip oscillator clock (B) to high-speed system clock (C)
(Setting sequence of SFR registers)
Setting Flag of SFR Register
Status Transition
CMC Register
Note 1
OSTS
Register
CSC
Register
OSTC Register
CKC
Register
EXCLK OSCSEL AMPH
MSTOP
MCM0
(B)
(C)
(X1 clock: 1 MHz
fX
10 MHz)
0 1 0
Note 2
0
Must be checked
1
(B)
(C)
(X1 clock: 10 MHz < fX
20 MHz)
0 1 1
Note 2
0
Must be checked
1
(B)
(C)
(external main clock)
1 1
Note 2
0
Must not be checked
1
Unnecessary if these registers
are already set
Unnecessary if the CPU is operating with
the high-speed system clock
Notes 1.
The clock operation mode control register (CMC) can be changed only once after reset release. This
setting is not necessary if it has already been set.
2.
Set the oscillation stabilization time as follows.
Desired the oscillation stabilization time counter status register (OSTC) oscillation stabilization time
Oscillation stabilization time set by the oscillation stabilization time select register (OSTS)
Caution Set the clock after the supply voltage has reached the operable voltage of the clock to be set (see
CHAPTER 27 ELECTRICAL SPECIFICATIONS).
Remarks
1.
×: don’t care
2.
(A) to (H) in Table 5-3 correspond to (A) to (H) in Figure 5-14.
(4) CPU clock changing from high-speed system clock (C) to high-speed on-chip oscillator clock (B)
(Setting sequence of SFR registers)
Setting Flag of SFR Register
Status Transition
CSC Register
Oscillation accuracy
stabilization time
CKC Register
HIOSTOP MCM0
(C)
(B)
0 18
μ
s to 65
μ
s 0
Unnecessary if the CPU is operating with the
high-speed on-chip oscillator clock
Remarks
1.
(A) to (H) in Table 5-3 correspond to (A) to (H) in Figure 5-14
2.
The oscillation accuracy stabilization time changes according to the temperature conditions and the
STOP mode period.