
Interrupt Controller (INTC)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
375
15.6.4
Order of execution
An ISR with a higher priority can preempt an ISR with a lower priority, regardless of the unique vectors
associated with each of their peripheral or software configurable interrupt requests. However, if multiple
peripheral or software configurable interrupt requests are asserted, more than one has the highest priority,
and that priority is high enough to cause preemption, the INTC selects the one with the lowest unique
vector regardless of the order in time that they asserted. However, the ability to meet deadlines with this
scheduling scheme is no less than if the ISRs execute in the time order that their peripheral or software
configurable interrupt requests asserted.
shows the order of execution of both ISRs with different priorities, and with
the same priority.
Table 15-9. Order of ISR Execution Example
Step
Step Description
Code Executing At End of Step
PRI in
INTC_CPR
at End of
Step
RTOS
ISR108
1
1
ISR108 executes for peripheral interrupt request 100 because the first eight ISRs are for software configurable interrupt
requests.
ISR208
ISR308 ISR408
Interrupt
Exception
Handler
1
RTOS at priority 0 is executing.
X
0
2
Peripheral interrupt request 100 at
priority 1 asserts. Interrupt taken.
X
1
3
Peripheral interrupt request 400 at
priority 4 asserts. Interrupt taken.
X
4
4
Peripheral interrupt request 300 at
priority 3 asserts.
X
4
5
Peripheral interrupt request 200 at
priority 3 asserts.
X
4
6
ISR408 completes. Interrupt exception
handler writes to INTC_EOIR.
X
1
7
Interrupt taken. ISR208 starts to
execute, even though peripheral
interrupt request 300 asserted first.
X
3
8
ISR208 completes. Interrupt exception
handler writes to INTC_EOIR.
X
1
9
Interrupt taken. ISR308 starts to
execute.
X
3
10
ISR308 completes. Interrupt exception
handler writes to INTC_EOIR.
X
1
11
ISR108 completes. Interrupt exception
handler writes to INTC_EOIR.
X
0
12
RTOS continues execution.
X
0
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...