W77E058A40DL Datasheet, PDF (50/87 Pages) Nuvotem Talema – GENERAL DESCRIPTION

W77E058A
11.2 Priority Level Structure
There are three priority levels for the interrupts, highest, high and low. The interrupt sources can be
individually set to either high or low levels. Naturally, a higher priority interrupt cannot be interrupted by
a lower priority interrupt. However there exists a pre-defined hierarchy amongst the interrupts
themselves. This hierarchy comes into play when the interrupt controller has to resolve simultaneous
requests having the same priority level. This hierarchy is defined as shown below; the interrupts are
numbered starting from the highest priority to the lowest.
Table 7. Priority structure of interrupts
SOURCE
External Interrupt 0
Timer 0 Overflow
External Interrupt 1
Timer 1 Overflow
Serial Port
Timer 2 Overflow
Serial Port 1
External Interrupt 2
External Interrupt 3
External Interrupt 4
External Interrupt 5
Watchdog Timer
FLAG
IE0
TF0
IE1
TF1
RI + TI
TF2 + EXF2
RI_1 + TI_1
IE2
IE3
IE4
IE5
WDIF
PRIORITY LEVEL
1(highest)
2
3
4
5
6
7
8
9
10
11
12 (lowest)
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