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MB90335 Series
■ Example of Multiple Interrupts
Aa an example of multiple interrupt processing, set the 8/16-bit PPG timer interrupt level to 2 and the timer
interrupt level to "1", considering a case when timer interrupts are to be given higher priority than 8/16-bit
PPG timer interrupts. At this time, the handling is executed as shown in Figure 3.4-5 if a time interrupt is
generated during the 8/16-bit PPG timer handling.
Main program
Initialize
peripheral
PPG timer interrupt
generation
Main processing
restart
●
PPG timer Interruption generation
At the start of the PPG timer interrupt handling, the ILM is automatically set to the same value as the PPG
timer interrupt level (IL2 to IL0 in ICR). If a Level 1 or 0 interrupt request is generated, the interrupt
handling makes it a higher priority in execution.
●
End of interrupt processing
When the interrupt processing has completed and the return instruction (RETI) is executed, the values of
the dedicated registers (A, DPR, ADB, DTB, PCB, PC, PS) saved in the stack are returned and the interrupt
level mask register (ILM) has the values before the interrupt.
CM44-10137-6E
Figure 3.4-5 Example of Multiple Interrupts
PPG timer interrupt processing Timer interrupt processing
Interrupt level 2
(ILM=010
)
B
(1)
(2)
Suspend
Restart
(8)
FUJITSU MICROELECTRONICS LIMITED
Interrupt level 1
(ILM=001
)
B
Timer interrupt
(3)
generation
PPG timer interrupt
(6)
processing
PPG timer interrupt return
(7)
CHAPTER 3 INTERRUPT
3.4 Hardware Interrupt
Timer interrupt
(4)
processing
Timer interrupt
(5)
return
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