Freescale Semiconductor MC68HC08KH12 - Manual (Page 72)

Advance Information MC68HC(7)08KH12 — Rev. 1.1
72 Freescale Semiconductor
7.6 Exception Control
Normal, sequential program execution can be changed in three different
ways:
• Interrupts
– Maskable hardware CPU interrupts
– Non-maskable software interrupt instruction (SWI)
• Reset
• Break interrupts
7.6.1 Interrupts
An interrupt temporarily changes the sequence of program execution to
respond to a particular event.
Figure 7-8 flow charts the handling of
system interrupts.
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).