
(1)
Normal release mode (IMF, EF5, TBTCR<TBTEN> = "0")
The IDLE0 or SLEEP0 mode is released when the falling edge of the source clock selected at
TBTCR<TBTCK> is detected. After the IDLE0 or SLEEP0 mode is released, the operation is restarted
by the instruction that follows the IDLE0 or SLEEP0 mode start instruction.
When TBTCR<TBTEN> is "1", the time base timer interrupt latch is set.
(2)
Interrupt release mode (IMF, EF5, TBTCR<TBTEN> = "1")
The IDLE0 or SLEEP0 mode is released when the falling edge of the source clock selected at
TBTCR<TBTCK> is detected. After the release, the INTTBT interrupt processing is started.
Note 1: The IDLE0 or SLEEP0 mode is released to the NORMAL1 or SLOW1 mode by the asynchronous
internal clock selected at TBTCR<TBTCK>. Therefore, the period from the start to the release of
the mode may be shorter than the time specified at TBTCR<TBTCK>.
Note 2: When a watchdog timer interrupt is generated immediately before the IDLE0 or SLEEP0 mode is
started, the watchdog timer interrupt will be processed but the IDLE0 or SLEEP0 mode will not be
started.
2.3.6.4
SLOW mode
The SLOW mode is controlled by system control register 2 (SYSCR2).
(1)
Switching from the NORMAL2 mode to the SLOW1 mode
Set SYSCR2<SYSCK> to "1".
When a maximum of 2/fcgck + 10/fs [s] has elapsed since SYSCR2<SYSCK> is set to "1", the main
system clock (fm) is switched to fs/4.
After switching, wait for 2 machine cycles or longer, and then clear SYSCR2<XEN> to "0" to turn
off the high-frequency clock oscillator.
If the oscillation of the low-frequency clock (fs) is unstable, confirm the stable oscillation at the warm-
up counter before implementing the procedure described above.
Note 1: Be sure to follow this procedure to switch the operation from the NORMAL2 mode to the SLOW1
mode.
Note 2: It is also possible to allow the basic clock for the high-frequency clock to oscillate continuously to
return to NORMAL2 mode. However, be sure to turn off the oscillation of the basic clock for the
high-frequency clock when the STOP mode is started from the SLOW mode.
Note 3: After switching SYSCR2<SYSCK>, be sure to wait for 2 machine cycles or longer before clearing
SYSCR2<XEN> to "0". Clearing it within 2 machine cycles causes a system clock reset.
Note 4: When the main system clock (fm) is switched, the gear clock (fcgck) is synchronized with the clock
that is a quarter of the basic clock (fs) for the low-frequency clock. For the synchronization, fm is
stopped for a period of 10/fs or shorter.
TMP89FH42
2. CPU Core
2.3 System clock controller
Page 36
RA004