Advance Information MC68HC908MR16/MC68HC908MR32 — Rev. 4.0
78 Central Processor Unit (CPU) MOTOROLA
Central Processor Unit (CPU)
6.6.1 Wait Mode
The WAIT instruction:
Clears the interrupt mask (I bit) in the condition code register,
enabling interrupts. After exit from wait mode by interrupt, the I bit
remains clear. After exit by reset, the I bit is set.
Disables the CPU clock
6.6.2 Stop Mode
The STOP instruction:
Clears the interrupt mask (I bit) in the condition code register,
enabling external interrupts. After exit from stop mode by externa l
interrupt, the I bit remains clear. After exit by reset, the I bit is set.
Disables the CPU clock
After exiting stop mode, the CPU clock begins running after the oscillator
stabilization delay.
6.7 CPU During Break Interrupts
If a break module is present on the MCU, the CPU starts a break
interrupt by:
Loading the instruction register with the software interrupt (SWI)
instruction
Loading the program counter with $FFFC:$FFFD or with
$FEFC:$FEFD in monitor mode
The break interrupt begins after completion of the CPU instruction in
progress. If the break address register match occurs on the last cycle of
a CPU instruction, the break interrupt begins immediately.
A return-from-interrupt instruction (RTI) in the break routine ends the
break interrupt and returns the MCU to normal operation if the break
interrupt has been deasserted.