MC68HC05X4 Datasheet, PDF (53/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Resets, Interrupts and Low Power Modes
Low power modes
WAIT:
(CIRQ or WOI) occurs or the device is reset. However the
processor will only stop the oscillator if the MCAN is in
‘sleep’ mode. Otherwise only the MPU clocks will be
turned off and the MCAN will remain active.
The WAIT instruction causes all processor clocks to stop,
but leaves the timer clocks running. This ‘rest’ state of the
processor can be cleared by reset, an external interrupt
(CIRQ or WOI), or a timer interrupt (core or 16-bit). There
are no special WAIT vectors for these interrupts.
Low power modes
STOP
The STOP instruction places the MCU in its lowest power consumption
mode. In STOP mode, the internal oscillator is turned off (providing the
MCAN is asleep, see Sleep mode), halting all internal processing,
including timer (and COP watchdog timer) operation.
During the STOP mode, the core timer interrupt flags (CTOF and RTIF)
and interrupt enable bits (CTOFE and RTIE) in the CTCSR, as well as
the timer flags in register TSR, and interrupt enable bits in register TCR,
are cleared by internal hardware. This removes any pending timer
interrupt requests and disables any further timer interrupts. The timer
prescaler is cleared. The I-bit in the CCR is cleared to enable external
interrupts. All other registers, the remaining bits in the CTCSR and
memory contents remain unaltered. All input/output lines remain
unchanged. The processor can be brought out of the STOP mode only
by an external interrupt (CIRQ or WOI) or a reset.
WAIT
The WAIT instruction places the MCU in a low-power consumption
mode, though it consumes more power than in STOP mode. All CPU
action is suspended, but the timers (core and 16-bit) remain active. An
interrupt from either of the timers, if enabled, will cause the MCU to exit
the WAIT mode.
7-resets
MOTOROLA
Resets, Interrupts and Low Power Modes
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MC68HC05X4 Rev 1.0
53