CHAPTER 5 CLOCK GENERATORS
User’s Manual U17446EJ3V1UD
79
(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 high-speed internal oscillation
clock operates as the system clock.
Figure 5-9. Status Transition of Default Start by High-Speed internal oscillation
HALT
instruction
STOP
instruction
Start with PCC = 02H,
PPCC = 02H
HALT
STOP
Interrupt
Reset signal
Interrupt
Power
application
Reset by
power-on-clear
High-speed internal
oscillator selected
by option byte
Clock division ratio
variable during
CPU operation
V
DD
> 2.1 V
±
0.1 V
Remark
PCC:
Processor clock control register
PPCC: Preprocessor clock control register
(2) Crystal/ceramic oscillator
If crystal/ceramic oscillation is selected by the option byte, a clock frequency of 1 to 10 MHz can be selected and
the accuracy of processing is improved because the frequency deviation is small, as compared with high-speed
internal oscillation (8 MHz (TYP.)).
Figures 5-10 and 5-11 show the timing chart and status transition diagram of default start by the crystal/ceramic
oscillator.