Renesas 7700 FAMILY User Manual page 74

Request
Reset
Time
Interrupt 1
Interrupt priority level=3
Interrupt 2
Interrupt priority level=5
Interrupt 3
Interrupt priority level=2
Fig. 4.9.1 Multiple interrupt mechanism
Nesting
Main routine
I = 1
IPL = 0
I = 0
Interrupt 1
I = 1
IPL = 3
I = 0
RTI
I = 0
IPL = 0
Interrupt 3
I = 1
IPL = 2
RTI
I = 0
IPL = 0
7751 Group User's Manual
INTERRUPTS
4.9 Multiple interrupts
Multiple interrupt
Interrupt 2
I = 1
IPL = 5
RTI
I = 0
IPL = 3
Interrupt 3
This request cannot be accepted
because its priority level is lower
than interrupt 1's.
The instruction of main routine is not
executed then.
I : Interrupt disable flag
IPL : processor interrupt priority level
: They are set automatically.
: Set by software.
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