CHAPTER 5 CLOCK GENERATORS
User’s Manual U16898EJ3V0UD
79
Figure 5-12. Timing of Default Start by External Clock Input
V
DD
(a)
(b)
External clock input
PCC = 02H, PPCC = 02H
H
RESET
System clock
Internal reset
CPU clock
Option byte is read.
System clock is selected.
(Operation stops
Note
)
Note
Operation stop time is 277
µ
s (MIN.), 544
µ
s (TYP.), and 1.075 ms (MAX.).
(a) The internal reset signal is generated by the power-on clear function on power application, the option byte is
referenced after reset, and the system clock is selected.
(b) The option byte is referenced and the system clock is selected. Then the external clock operates as the
system clock.
Figure 5-13. Status Transition of Default Start by External Clock Input
HALT
STOP
HALT
instruction
STOP
instruction
V
DD
> 2.1 V
±
0.1 V
Start with PCC = 02H,
PPCC = 02H
Interrupt
Reset signal
Interrupt
Power
application
Reset by
power-on clear
External clock input
selected by option byte
Clock division ratio
variable during
CPU operation
Remark
PCC: Processor clock control register
PPCC: Preprocessor clock control register