ST72324BJ2 datasheet(39/188 Pages) STMICROELECTRONICS

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ST72324B

Interrupts

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peripheral control register. The general sequence for clearing an interrupt is based on an

access to the status register followed by a read or write to an associated register.

Note:

The clearing sequence resets the internal latch. A pending interrupt (that is, waiting to be

serviced) is therefore lost if the clear sequence is executed.

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 Table 24: Interrupt mapping). When several pending interrupts are

present while exiting 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 process 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.

7.4

Concurrent and nested management

Figure 20 and Figure 21 show two different interrupt management modes. The first is called

concurrent mode and does not allow an interrupt to be interrupted, unlike the nested mode

in Figure 21. The interrupt hardware priority is given in order from the lowest to the highest

as follows: MAIN, IT4, IT3, IT2, IT1, IT0. Software priority is given for each interrupt.

Warning:

A stack overflow may occur without notifying the software of

the failure.

Figure 20.

Concurrent interrupt management

Main

IT4

IT2

IT1

TRAP

IT1

Main

IT0

Software

3/0

11/10

RIM

IT3

priority

level

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