Freescale Semiconductor, Inc.
Keyboard/External Interrupt Module (KBI)
Functional Description
NOTE: The interrupt mask (I) in the condition code register (CCR) masks all
interrupt requests, including external interrupt requests.
See Figure 14-3.
FROM RESET
YES
I BIT SET?
NO
YES
INTERRUPT?
NO
STACK CPU REGISTERS
SET I BIT
LOAD PC WITH INTERRUPT VECTOR
FETCH NEXT
INSTRUCTION
SWI
INSTRUCTION?
YES
YES
NO
RTI
UNSTACK CPU REGISTERS
EXECUTE INSTRUCTION
INSTRUCTION?
NO
Figure 14-3. IRQ Interrupt Flowchart
MC68HC908RFRK2
MOTOROLA
AdvanceInformation
187
Keyboard/External Interrupt Module (KBI)
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