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CHAPTER
5 C
L
OC
K
GENERA
TOR
User’s Manual
U1
9780EJ2V0UD
130
Figure 5-2. Block Diagram of Clock Generator (78K0/KC2-A)
Option byte
1: Cannot be stopped
0: Can be stopped
Internal oscillation
mode register
(RCM)
LSRSTOP
RSTS
RSTOP
Internal high-
speed oscillator
(8 MHz (TYP.))
Internal low-
speed oscillator
(240 kHz (TYP.))
f
RL
XT1/P123
XT2/P124
f
SUB
Peripheral
hardware
clock (f
PRS
)
Watchdog timer,
8-bit timer H1
Real-time counter,
clock output
1/2
CPU clock
(f
CPU
)
Processor clock
control register
(PCC)
CSS PCC2
CLS
PCC1 PCC0
Prescaler
Main system
clock switch
f
XP
Peripheral
hardware
clock switch
X1 oscillation
stabilization time counter
OSTS1 OSTS0
OSTS2
Oscillation stabilization
time select register (OSTS)
3
MOST
16
MOST
15
MOST
14
MOST
13
MOST
11
Oscillation
stabilization
time counter
status register
(OSTC)
Controller
MCM0
XSEL
MCS
MSTOP
EXCLK OSCSEL
AMPH
Clock operation mode
select register
(OSCCTL)
4
f
XP
2
f
XP
2
2
f
XP
2
3
f
XP
2
4
Main clock
mode register
(MCM)
Main clock
mode register
(MCM)
Main OSC
control register
(MOC)
f
RH
Internal bus
Internal bus
High-speed system
clock oscillator
Crystal/ceramic
oscillation
External input
clock
X1/P121
X2/EXCLK/
P122
f
XH
f
SUB
2
Crystal
oscillation
Subsystem
clock oscillator
f
X
f
EXCLK
f
XT
XTSTART
To subsystem
clock oscillator
OSCSELS
Clock operation mode
select register
(OSCCTL)
Selector
STOP