Datasheet

Resets and Interrupts
Interrupts
MC68HC908GR8 — Rev 4.0 Technical Data
MOTOROLA Resets and Interrupts 67
Figure 4-4. Interrupt Stacking Order
After every instruction, the CPU checks all pending interrupts if the I bit
is not set. If more than one interrupt is pending when an instruction is
done, the highest priority interrupt is serviced first. In the example shown
in Figure 4-5, if an interrupt is pending upon exit from the interrupt
service routine, the pending interrupt is serviced before the LDA
instruction is executed.
CONDITION CODE REGISTER
ACCUMULATOR
INDEX REGISTER (LOW BYTE)*
PROGRAM COUNTER (HIGH BYTE)
PROGRAM COUNTER (LOW BYTE)
•
•
•
•
•
•
1
2
3
4
5
5
4
3
2
1
STACKING
ORDER
*High byte of index register is not stacked.
$00FF DEFAULT ADDRESS ON RESET
UNSTACKING
ORDER
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