Fujitsu 8FX User Manual

MB95630H Series
24 FUJITSU SEMICONDUCTOR LIMITED MN702-00009-2v0-E
CHAPTER 3 CLOCK CONTROLLER
3.2 Oscillation Stabilization Wait Time
3.2 Oscillation Stabilization Wait Time
The oscillation stabilization wait time is the time after the oscillator circuit
stops oscillation until the oscillator resumes its stable oscillation at its natural
frequency. The clock controller obtains the oscillation stabilization wait time
after the start of oscillation by counting a specific number of oscillation clock
cycles. During the oscillation stabilization wait time, the clock controller stops
clock supply to internal circuits.
■ Oscillation Stabilization Wait Time
The clock controller obtains the oscillation stabilization wait time after the start of oscillation
by counting a specific number of oscillation clock cycles. During the oscillation stabilization
wait time, the clock controller stops clock supply to internal circuits.
When the power is switched on, or when a state transition request making the oscillator start
from the oscillation stop state is generated due to a change of clock mode caused by a reset, by
an interrupt in stop mode or by the software operation, before making the clock mode transit to
another mode, the clock controller automatically waits for the oscillation stabilization wait time
of the clock for that mode to elapse.
Figure 3.2-1 shows how the oscillator runs immediately after starting oscillating.
Figure 3.2-1 Behavior of Oscillator Immediately after Starting Oscillation
Oscillation stabilization wait time of main clock, subclock, main CR clock, main CR PLL
clock or sub-CR clock is counted by using a dedicated counter. The count value can be set in
the oscillation stabilization wait time setting register (WATR). Set it in keeping with the
oscillator characteristics.
When a power-on reset occurs, the oscillation stabilization wait time is fixed at the initial
value.
Table 3.2-1 shows the length of oscillation stabilization wait time.
Oscillation stabilization
wait time
()
Normal operation
Operation after returning
from stop mode or a reset
Oscillation started
X1
Oscillation time of
oscillator
Oscillation stabilized
Table 3.2-1 Oscillation Stabilization Wait Time
Clock Reset source Oscillation stabilization wait time
Main clock
Power-on reset
Initial value: (2
14
-2)/F
CH
(F
CH
: main clock frequency)
Other than power-on reset Register settings (WATR:MWT[3:0])
Subclock
Power-on reset
Initial value: (2
15
-2)/F
CL
(F
CL
: subclock frequency)
Other than power-on reset Register settings (WATR:SWT[3:0])

Fujitsu 8FX Specifications

General

Brand	Fujitsu
Model	8FX
Category	Computer Hardware
Language	English