ST92185B STMicroelectronics, ST92185B Datasheet - Page 45
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ST92185B
Manufacturer Part Number
ST92185B
Description
16k/24k/32k Rom Hcmos Mcu With On-screen-display
Manufacturer
STMicroelectronics
Datasheet
1.ST92185B.pdf
(178 pages)
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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 22. Simple Example of a Sequence of Interrupt Requests with:
- Concurrent mode selected and
- IEN unchanged by the interrupt routines
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
ST92185B - INTERRUPTS
Figure
22) the
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