Rev. 6.00, 08/04, page 137 of 628
2. Time for direct transition from active (medium-speed) mode to active (high-speed) mode
A direct transition from active (medium-speed) mode to active (high-speed) mode is performed by
executing a SLEEP instruction in active (medium-speed) mode while bits SSBY and LSON are
both cleared to 0 in SYSCR1, and bit MSON is cleared to 0 and bit DTON is set to 1 in SYSCR2.
The time from execution of the SLEEP instruction to the end of interrupt exception handling (the
direct transition time) is given by equation (2) below.
Direct transition time = { (Number of SLEEP instruction execution states) + (number of internal
processing states) } • (tcyc before transition) + (number of interrupt
exception handling execution states) • (tcyc after transition)
.................................. (2)
Example: Direct transition time = (2 + 1) • 14 • 2tosc = 76tosc (when
φ
/8 is selected as
the CPU operating clock)
[Legend]
tosc: OSC clock cycle time
tcyc: System clock (
φ
) cycle time
3. Time for direct transition from subactive mode to active (high-speed) mode
A direct transition from subactive mode to active (high-speed) mode is performed by executing a
SLEEP instruction in subactive mode while bit SSBY is set to 1 and bit LSON is cleared to 0 in
SYSCR1, bit MSON is cleared to 0 and bit DTON is set to 1 in SYSCR2, and bit TMA3 is set to 1
in TMA. The time from execution of the SLEEP instruction to the end of interrupt exception
handling (the direct transition time) is given by equation (3) below.
Direct transition time = { (Number of SLEEP instruction execution states) + (number of internal
processing states) } • (tsubcyc before transition) + { (wait time set in
STS2 to STS0) + (number of interrupt exception handling execution
states) } • (tcyc after transition)
........................ (3)
Example: Direct transition time = (2 + 1) • 8tw + (8192 + 14) • 2tosc = 24tw + 16412tosc (when
φ
w/8 is selected as the CPU operating clock, and wait time = 8192 states)
[Legend]
tosc:
OSC clock cycle time
tw:
Watch clock cycle time
tcyc:
System clock (
φ
) cycle time
tsubcyc: Subclock (
φ
SUB
) cycle time
Summary of Contents for H8/38024 Series
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