Renesas H8 Series Hardware Manual page 158

Section 4 Clock Pulse Generators
1. Oscillation stabilization time (t
The time from the point at which the system clock oscillator oscillation waveform starts to change
when an interrupt is generated, until the amplitude of the oscillation waveform increases and the
oscillation frequency stabilizes.
2. Wait time
The time required for the CPU and peripheral functions to begin operating after the oscillation
waveform frequency and system clock have stabilized.
The wait time setting is selected with standby timer select bits 2 to 0 (STS2 to STS0) (bits 6 to 4 in
system control register 1 (SYSCR1)).
Oscillation
waveform
(OSC2)
System clock
(φ)
Oscillation
stabilization
time
Standby mode,
Operating
watch mode,
mode
or subactive
mode
When standby mode, watch mode, or subactive mode is cleared by an interrupt or reset, and a
transition is made to active (high-speed/medium-speed) mode, the oscillation waveform begins to
change at the point at which the interrupt is accepted. Therefore, when an oscillator element is
connected in standby mode, watch mode, or subactive mode, since the system clock oscillator is
halted, the time from the point at which this oscillation waveform starts to change until the
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)
rc
Oscillation stabilization wait time
Interrupt accepted
Figure 4.14 Oscillation Stabilization Wait Time
Wait time
Active (high-speed) mode or
active (medium-speed) mode