CHAPTER 5 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U13850EJ4V0UM
137
Figure 5-9. Example of Interrupt Nesting Service (1/2)
Main routine
EI
EI
Interrupt request a
(level 3)
Servicing of a
Servicing of b
Interrupt
request b
(level 2)
Servicing of c
Interrupt request c
(level 3)
Interrupt request d
(level 2)
Servicing of d
Servicing of e
EI
Interrupt request e
(level 2)
Interrupt request f
(level 3)
Servicing of f
EI
Servicing of g
Interrupt request g
(level 1)
Interrupt request h
(level 1)
Servicing of h
Interrupt request h is held pending even if interrupts are
enabled because its priority is the same as that of g.
Interrupt request f is held pending even if interrupts are
enabled because its priority is lower than that of e.
Interrupt request b is acknowledged because the priority of
b is higher than that of a and interrupts are enabled.
Although the priority of interrupt request d is higher
than that of c, d is held pending because interrupts
are disabled.
Caution The values of EIPC and EIPSW must be saved before executing multiple interrupts.
Remarks 1.
a to u in the figure are the names of interrupt requests shown for the sake of explanation.
2.
The default priority in the figure indicates the relative priority between two interrupt requests.
Содержание MPD703030A
Страница 2: ...User s Manual U13850EJ4V0UM 2 MEMO ...
Страница 514: ...User s Manual U13850EJ4V0UM 514 MEMO ...