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CHAPTER 5 CLOCK GENERATOR
User’s Manual U19780EJ2V0UD
163
Table 5-5. CPU Clock Transition and SFR Register Setting Examples (4/5)
(9) CPU clock changing from subsystem clock (D) to high-speed system clock (C)
Note
Note
The 78K0/KB2-A is not provided with a subsystem clock.
(Setting sequence of SFR registers)
Setting Flag of SFR Register
Status Transition
AMPH
Note
EXCLK OSCSEL
MSTOP OSTC
Register
XSEL
Note
MCM0 CSS
(D)
→
(C) (X1 clock: 1 MHz
≤
f
XH
≤
10 MHz)
0 0 1 0
Must be
checked
1 1 0
(D)
→
(C) (external main clock: 1 MHz
≤
f
XH
≤
10 MHz
0 1 1 0
Must not be
checked
1 1 0
(D)
→
(C) (X1 clock: 10 MHz < f
XH
≤
20 MHz)
1 0 1 0
Must be
checked
1 1 0
(D)
→
(C) (external main clock: 10 MHz <
f
XH
≤
20 MHz)
1 1 1 0
Must not be
checked
1 1 0
Unnecessary if these registers
are already set
Unnecessary if the
CPU is operating
with the high-speed
system clock
Unnecessary if this register
is already set
Note
The value of this flag can be changed only once after a reset release. This setting is not necessary if it has
already been set.
Caution
Set the X1 clock after the supply voltage has reached the operable voltage of the clock to be used
(see CHAPTER 28 ELECTRICAL SPECIFICATIONS).
(10)
•
HALT mode (E) set while CPU is operating with internal high-speed oscillation clock (B)
•
HALT mode (F) set while CPU is operating with high-speed system clock (C)
•
HALT mode (G) set while CPU is operating with subsystem clock (D)
Note
Status Transition
Setting
(B)
→
(E)
(C)
→
(F)
(D)
→
(G)
Note
Executing HALT instruction
Note
The 78K0/KB2-A is not provided with a subsystem clock.
Remarks 1.
(A) to (I) in Table 5-5 correspond to (A) to (I) in Figures 5-15 and 5-16.
2.
EXCLK, OSCSEL, AMPH: Bits 7, 6, and 0 of the clock operation mode select register (OSCCTL)
MSTOP:
Bit 7 of the main OSC control register (MOC)
XSEL, MCM0:
Bits 2 and 0 of the main clock mode register (MCM)
CSS:
Bit 4 of the processor clock control register (PCC)