
External Interrupt (IRQ)
MC68HC05C8A MC68HCL05C8A MC68HSC05C8A Data Sheet, Rev. 5.1
Freescale Semiconductor
31
Figure 4-1. Interrupt Flowchart
INTERNAL
TIMER
INTERRUPT
?
INTERNAL
SCI
INTERRUPT
?
N
RESTORE REGISTERS
FROM STACK:
CCR, A, X, PC
IRQ
EXTERNAL
INTERRUPT
?
LOAD PC FROM:
SWI: $1FFC-$1FFD
IRQ: $1FFA-$1FFB
TIMER: $1FF8-$1FF9
SCI: $1FF6-$1FF7
SET I BIT IN
CC REGISTER
STACK
PC, X, A, CCR
CLEAR IRQ
REQUEST LATCH
FETCH NEXT
INSTRUCTION
EXECUTE
INSTRUCTION
N
Y
N
I BIT
IN CCR SET?
INTERNAL
SPI
INTERRUPT
?
SWI
INSTRUCTION
?
N
Y
RTI
INSTRUCTION
?
Y
FROM
RESET
N
Y
N
Y