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CHAPTER 22 INTERRUPT FUNCTIONS
User’s Manual U12697EJ3V0UM
Figure 22-14. Examples of Servicing When Another Interrupt Request Is Generated During Interrupt Service (1/3)
Main routine
EI
EI
EI
Interrupt request a
(Level 3)
Interrupt
request b
(Level 2)
Interrupt
request d
(Level 2)
Interrupt request e
(Level 2)
Interrupt
request f
(Level 3)
Interrupt request g
(Level 1)
a servicing
b servicing
c servicing
d servicing
e servicing
f servicing
g servicing
h servicing
Since interrupt request b has a higher
priority than interrupt request a, and
interrupts are enabled, interrupt
request b is acknowledged.
The priority of interrupt request d is
higher than that of interrupt request c,
but since interrupts are disabled,
interrupt request d is held pending.
Although interrupts are enabled,
interrupt request f is held pending
since it has a lower priority than
interrupt request e.
Although interrupts are enabled,
interrupt request h is held pending
since it has the same priority as
interrupt request g.
Interrupt
request h
(Level 1)
EI
Interrupt request c
(Level 3)
