ST92163R4D0 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST92163R4D0

8/16-BIT FULL SPEED USB MCU FOR COMPOSITE DEVICES WITH 16 ENDPOINTS, 20K ROM, 2K RAM, I2C, SCI, & MFT

STMicroelectronics 

ST92163 - 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.

Example 1

In the first example, (simplest case, Figure 22) the

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.

Figure 22. Simple Example of a Sequence of Interrupt Requests with:

- Concurrent mode selected and

- IEN unchanged by the interrupt routines

0

Priority Level of

Interrupt Request

1

INTERRUPT 2 HAS PRIORITY LEVEL 2

INTERRUPT 3 HAS PRIORITY LEVEL 3

INTERRUPT 4 HAS PRIORITY LEVEL 4

INTERRUPT 5 HAS PRIORITY LEVEL 5

2

3

INT 2

4

INT 3

INT 4

5

INT 5

ei CPL = 7

6

INT 5

7

MAIN

CPL is set to 7

INT 2

CPL = 7

INT 3

CPL = 7

INT 4

CPL = 7

MAIN

CPL = 7

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