MC68HC908RK2 Datasheet, PDF (86/158 Pages) Motorola, Inc – Microcontroller Unit

Keyboard/External Interrupt Module (KBI)
When set, the IMASKI and IMASKK bits in the INTKBSCR masks all external interrupt requests. A latched
interrupt request is not presented to the interrupt priority logic unless the corresponding IMASK<x> bit is
clear.
NOTE
The interrupt mask (I) in the condition code register (CCR) masks all
interrupt requests, including external interrupt requests. (See Figure 7-4.)
FROM RESET
YES
I BIT SET?
NO
INTERRUPT?
NO
YES
STACK CPU REGISTERS
SET I BIT
LOAD PC WITH INTERRUPT VECTOR
FETCH NEXT
INSTRUCTION
SWI
YES
INSTRUCTION?
NO
RTI
YES
INSTRUCTION?
UNSTACK CPU REGISTERS
NO
EXECUTE INSTRUCTION
Figure 7-4. IRQ Interrupt Flowchart
MC68HC908RK2 Data Sheet, Rev. 5.1
86
Freescale Semiconductor