MC68HC05P18A Datasheet, PDF (41/130 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

MC68HC05P18A
Freescale Semiconductor, Inc.
Interrupts
CPU Interrupt Processing
causes the CPU state to be recovered from the stack and normal
processing to resume at the next instruction that was to be executed
when the interrupt took place. Figure 4-1 shows the sequence of events
that occur during interrupt processing.
FROM RESET
Y
IS I BIT
SET?
N
IRQ
Y
INTERRUPT?
N
TIMER
Y
INTERRUPT?
N
CLEAR IRQ
REQUEST
LATCH
STACK
PC, X, A, CC
SET
I BIT IN CCR
LOAD PC FROM
SWI: $3FFC AND $3FFD
IRQ: $3FFA–$3FFB
TIMER: $3FF8–$3FF9
FETCH NEXT INSTRUCTION
SWI
Y
INSTRUCTION?
N
RTI
Y
INSTRUCTION?
N
EXECUTE INSTRUCTION
RESTORE REGISTERS
FROM STACK
CC, A, X, PC
Figure 4-1. Interrupt Processing Flowchart
Interrupts
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Technical Data