ST72521M9T1 View Datasheet(PDF) - STMicroelectronics
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Description
Manufacturer
ST72521M9T1
STMicroelectronics
ST72521M9T1 Datasheet PDF : 211 Pages
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ST72521
INTERRUPTS (Cont’d)
7.3 INTERRUPTS AND LOW POWER MODES
All interrupts allow the processor to exit the WAIT
low power mode. On the contrary, only external
and other specified interrupts allow the processor
to exit from the HALT modes (see column “Exit
from HALT” in “Interrupt Mapping” table). When
several pending interrupts are present while exit-
ing HALT mode, the first one serviced can only be
an interrupt with exit from HALT mode capability
and it is selected through the same decision proc-
ess shown in Figure 19.
Note: If an interrupt, that is not able to Exit from
HALT mode, is pending with the highest priority
when exiting HALT mode, this interrupt is serviced
after the first one serviced.
Figure 20. Concurrent Interrupt Management
7.4 CONCURRENT & NESTED MANAGEMENT
The following Figure 20 and Figure 21 show two
different interrupt management modes. The first is
called concurrent mode and does not allow an in-
terrupt to be interrupted, unlike the nested mode in
Figure 21. The interrupt hardware priority is given
in this order from the lowest to the highest: MAIN,
IT4, IT3, IT2, IT1, IT0, TLI. The software priority is
given for each interrupt.
Warning: A stack overflow may occur without no-
tifying the software of the failure.
SOFTWARE
PRIORITY
I1
I0
LEVEL
TRAP
IT0
IT1
IT1
IT2
IT3
RIM
IT4
MAIN
11 / 10
MAIN
10
3
11
3
11
3
11
3
11
3
11
3
11
3/0
Figure 21. Nested Interrupt Management
IT1
IT2
TRAP
IT0
RIM
MAIN
11 / 10
IT4
IT4
IT1
IT3
SOFTWARE
PRIORITY
I1
I0
LEVEL
IT2
MAIN
10
3
11
3
11
2
00
1
01
3
11
3
11
3/0
35/211
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