CHAPTER 5 CLOCK GENERATORS
User’s Manual U18172EJ2V0UD
66
Figure 5-1. Block Diagram of Clock Generators
X1/P23/ANI3
X2/P22/ANI2
f
X
f
X
2
PCC1
Controller
Selector
CPU clock
(f
CPU
)
Internal bus
Internal bus
Oscillation stabilization
time select register (OSTS)
Preprocessor clock
control register (PPCC)
Processor clock
control register (PCC)
STOP
PPCC1 PPCC0
OSTS1 OSTS0
f
XP
2
2
f
XP
f
X
2
2
f
RL
LSRSTOP
CPU
System clock oscillation
stabilization time counter
Selector
Prescaler
Clock to peripheral
hardware (f
XP
)
8-bit timer H1,
watchdog timer
Option byte
1: Cannot be stopped.
0: Can be stopped.
Low-speed internal oscillation
mode register (LSRCM)
Low-speed
internal
oscillator
Prescaler
System clock
oscillator
Note
External clock
input
Crystal/ceramic
oscillation
High-speed
internal
oscillation
Watchdog timer
Note
Select the high-speed internal oscillator, crystal/ceramic oscillator, or external clock input circuit as the
system clock source by using the option byte.