mc68hc908kx8 Freescale Semiconductor, Inc, mc68hc908kx8 Datasheet - Page 144

• Manufacturer Part Number: mc68hc908kx8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

System Integration Module (SIM)
13.5.1.1 Hardware Interrupts
A hardware interrupt does not stop the current instruction. Processing of a hardware interrupt begins after
completion of the current instruction. When the current instruction is complete, the SIM checks all pending
hardware interrupts. If interrupts are not masked (I bit clear in the condition code register), and if the
corresponding interrupt enable bit is set, the SIM proceeds with interrupt processing; otherwise, the next
instruction is fetched and executed.
If more than one interrupt is pending at the end of an instruction execution, the highest priority interrupt is
serviced first.
144
Figure 13-10
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 Data Sheet, Rev. 2.1
demonstrates what happens when two interrupts are pending. If an interrupt
YES
INSTRUCTION
Figure 13-9. Interrupt Processing
INSTRUCTION
FETCH NEXT
INSTRUCTION
FROM RESET
ICG CLK MON
INTERRUPT
INTERRUPTS
INTERRUPT
I BIT SET?
I BIT SET?
OTHER
IRQ1
SWI
RTI
?
?
?
?
?
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
LOAD PC WITH INTERRUPT VECTOR
UNSTACK CPU REGISTERS
EXECUTE INSTRUCTION
STACK CPU REGISTERS
SET I BIT
Freescale Semiconductor