ST92195C STMicroelectronics, ST92195C Datasheet - Page 47

• Manufacturer Part Number: ST92195C
• Description: 48-96 Kbyte Rom Hcmos Mcu With On-screen Display And Teletext Data Slicer
• Manufacturer: STMicroelectronics

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 21. 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,
page
interrupt service routines. This means that no new
interrupt can be serviced in the middle of the cur-
rent one. The interrupt routines will thus be serv-
iced one after another, in the order of their priority,
until the main program eventually resumes.
INT 4
47) the ei instruction is not used within the
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
ST92195C/D - INTERRUPTS
Figure 21 on
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