Datasheet

System Integration Module (SIM)
MC68HC908LJ12 — Rev. 2.1 Technical Data
Freescale Semiconductor System Integration Module (SIM) 143
Interrupts are latched, and arbitration is performed in the SIM at the start
of interrupt processing. The arbitration result is a constant that the CPU
uses to determine which vector to fetch. Once an interrupt is latched by
the SIM, no other interrupt can take precedence, regardless of priority,
until the latched interrupt is serviced (or the I bit is cleared).
(See Figure 9-10.)
Figure 9-10. Interrupt Processing
NO
NO
NO
YES
NO
NO
YES
YES
AS MANY INTERRUPTS
I BIT SET?
FROM RESET
BREAK
I-BIT SET?
IRQ
INTERRUPT?
SWI
INSTRUCTION?
RTI
INSTRUCTION?
FETCH NEXT
INSTRUCTION
UNSTACK CPU REGISTERS
STACK CPU REGISTERS
SET I-BIT
LOAD PC WITH INTERRUPT VECTOR
EXECUTE INSTRUCTION
YES
YES
AS EXIST ON CHIP
INTERRUPT?