Advance Information MC68HC908MR16/MC68HC908MR32 — Rev. 4.0

332 External Interrupt (IRQ) MOTOROLA

External Interrupt (IRQ)
Figure 17-3. IRQ Interrupt Flowchart
FROM RESET
I BIT SET?
FETCH NEXT
YES
NO
INTERRUPT?
INSTRUCTION
SWI
INSTRUCTION?
RTI
INSTRUCTION?
NO
STACK CPU REGISTERS
NO
SET I BIT
LOAD PC WITH INTERRUPT VECTOR
NO
YES UNSTACK CPU REGISTERS
EXECUTE INSTRUCTION
YES
YES