Oscillation Stabilization Wait Time - Fujitsu 8FX Hardware Manual

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
X1
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.
Table 3.2-1 Oscillation Stabilization Wait Time
Clock
Main clock
Subclock
24
Oscillation time of Oscillation stabilization
oscillator
Oscillation started
Reset source
Power-on reset
Other than power-on reset
Power-on reset
Other than power-on reset
FUJITSU SEMICONDUCTOR LIMITED
MB95630H Series
Normal operation
(
Operation after returning
from stop mode or a reset
wait time
Oscillation stabilized
Oscillation stabilization wait time
14
Initial value: (2 -2)/F (F
CH
Register settings (WATR:MWT[3:0])
15
Initial value: (2 -2)/F (F
CL
Register settings (WATR:SWT[3:0])
)
: main clock frequency)
CH
: subclock frequency)
CL
MN702-00009-2v0-E