CHAPTER 6 CLOCK GENERATOR
Page 131 of 920
Table 6 - 4 CPU Clock Transition and SFR Register Setting Examples (2/5)
(4) CPU clock changing from high-speed on-chip oscillator clock (B) to high-speed system clock (C)
Note 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.
Note 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 31
ELECTRICAL SPECIFICATIONS).
(5) CPU clock changing from high-speed on-chip oscillator clock (B) to subsystem clock (D)
Note
The clock operation mode control register (CMC) can be written only once by an 8-bit memory manipulation instruction
after reset release. This setting is not necessary if it has already been set.
Remark 1.
×
: Don’t care
Remark 2.
(A) to (J) in Tables 6 - 3 to 6 - 7 correspond to (A) to (J) in Figure 6 - 19.
(Setting sequence of SFR registers)
Setting Flag of SFR Register
OSTS
Register
CSC
Register
OSTC
Register
CKC
Register
Status Transition
EXCLK
OSCSEL
AMPH
MSTOP
MCM0
(B)
→
(C)
(XT1 clock: 1 MHz
≤
f
X
≤
10 MHz)
0
1
0
0
Must be
checked
1
(B)
→
(C)
(XT1 clock: 10 MHz
<
f
X
≤
20 MHz)
0
1
1
0
Must be
checked
1
(B)
→
(C)
(external main clock)
1
1
×
0
Need not
be checked
1
Unnecessary if these registers are
already set
Unnecessary if the CPU is
operating with the high-speed
system clock
(Setting sequence of SFR registers)
Setting Flag of SFR Register
CSC
Register
Waiting for
Oscillation
Stabilization
CKC
Register
Status Transition
EXCLKS
OSCSELS
AMPHS1,0
XTSTOP
CSS
(B)
→
(D)
(XT1 clock)
0
1
00: Low power consumption
oscillation
01: Normal oscillation
10: Ultra-low power
consumption oscillation
0
Necessary
1
(B)
→
(D)
(external sub clock)
1
1
×
0
Necessary
1
Unnecessary if these registers are already set
Unnecessary if the CPU is operating
with the subsystem clock
Содержание RL78/G1H
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