MC68HC705P9 Datasheet, PDF (68/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Low-Power Modes _{Wait Mode}
Wait Mode
The WAIT instruction puts the MCU in an intermediate
power-consumption mode and has the following effects on the MCU:
• Clears the I bit in the condition code register, enabling interrupts
• Stops the CPU clock, but allows the internal clock to drive the
capture/compare timer, the COP watchdog, and the ADC
The WAIT instruction does not affect any other registers or any I/O lines.
The following conditions restart the CPU clock and bring the MCU out of
wait mode:
• External interrupt — A high-to-low transition on the IRQ/V_PP pin
loads the program counter with the contents of locations $1FFA
and $1FFB.
• Timer interrupt — Input capture, output compare, and timer
overflow interrupt requests load the program counter with the
contents of locations $1FF8 and $1FF9.
• COP watchdog reset — A timeout of the COP watchdog resets the
MCU and loads the program counter with the contents of locations
$1FFE and $1FFF. Software can enable timer interrupts so that
the MCU can periodically exit wait mode to reset the COP
watchdog.
• External reset — A logic zero on the RESET pin resets the MCU
and loads the program counter with the contents of locations
$1FFE and $1FFF.
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Low-Power Modes
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