User guide

16
SmartBook for Renesas R8C/Tiny Microcontrollers
www.MightyMicons.com
2.7 Wait Mode:
Getting into the wait mode is as easy as executing
the WAIT instruction at any point of the application
execution. In this wait mode, CPU system clock is
switched off and subsequently the CPU and the
watchdog timer are turned off to conserve the power.
Since the main clock and the ring oscillator are already
in on condition, peripheral functions can use them. When
the micon enters into this wait mode, pin status of the micon
remain same as that of operating condition prior to the wait
mode entry.
In the wait mode, the peripheral function clocks can also be stopped to
conserve more power. If the CM02 bit is set to 1, the clock divider is switched
off to stop f1, f 2, f 8, f 32, f1SIO, f8SIO, f32SIO and fAD clocks. But other
clocks, fRING, fRING128, fRING-FAST derived from ring oscillators can be used
for the applications.
To exit from the wait mode, a hardware reset or a peripheral function interrupt is
required. If the peripheral function clocks are already disabled in the wait mode,
only the peripheral functions which can use the external signals can activate an
interrupt to exit from the wait mode. Because of this, the program flow should
keep the interrupt conditions of the peripheral functions in the active condition,
which are likely to trigger the micon from the wait mode. The CPU clock turned on
when returning from the wait mode by a peripheral function interrupt is the same
CPU clock that was operating when the wait instruction is executed.
2.8 Stop Mode:
The stop mode is the operating mode consuming least amount of power among all
the modes because all the clocks are turned off. The microcomputer is placed
into this mode by stopping all the operating clocks (set CM10=1). But before
entering into stop mode, oscillator stop detection function should be disabled.
During active stop mode condition, pin status of the micon is maintained as the
operating condition prior to stop mode entry. If the operating voltage at the Vcc
pin is VRAM or more, the contents of the internal RAM area remain same as
before.
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Getting into the wait
mode is as easy as
executing the WAIT
instruction at any
point of the
application execution. The stop mode is the
operating mode consuming least amount
of power among all the modes because
all the clocks are turned off. The
microcomputer is placed into this
mode by stopping all the
operating clocks (set
CM10=1).