ST92F150-DBE STMicroelectronics, ST92F150-DBE Datasheet - Page 96

• Manufacturer Part Number: ST92F150-DBE
• Description: MCU, MPU & DSP Development Tools ST9 Dedication Board
• Manufacturer: STMicroelectronics

Specifications of ST92F150-DBE

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ST92F124/F150/F250 - INTERRUPTS
ARBITRATION MODES (Cont’d)
Examples
In the following two examples, three interrupt re-
quests with different priority levels (2, 3 & 4) occur
simultaneously during the interrupt 5 service rou-
tine.
Figure 46. Simple Example of a Sequence of Interrupt Requests with:
- Concurrent mode selected and
- IEN unchanged by the interrupt routines
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9
0
1
2
3
4
5
6
7
CPL is set to 7
Priority Level of
Interrupt Request
MAIN
INT 5
ei
CPL = 7
INT 5
INT 2
INT 3
INT 4
CPL = 7
INT 2
CPL = 7
INT 3
CPL = 7
Example 1
In the first example, (simplest case,
ei instruction is not used within the interrupt serv-
ice routines. This means that no new interrupt can
be serviced in the middle of the current one. The
interrupt routines will thus be serviced one after
another, in the order of their priority, until the main
program eventually resumes.
INT 4
CPL = 7
MAIN
INTERRUPT 2 HAS PRIORITY LEVEL 2
INTERRUPT 3 HAS PRIORITY LEVEL 3
INTERRUPT 4 HAS PRIORITY LEVEL 4
INTERRUPT 5 HAS PRIORITY LEVEL 5
Figure
46) the