GMS90C320

OCT. 2000 Ver 1.2

19

A low-priority interrupt can itself be interrupted by a high-priority interrupt, but not by another low priority interrupt. A high-

priority interrupt cannot be interrupted by any other interrupt source.

If two requests of different priority level are received simultaneously, the request of higher priority is serviced. If requests of

the same priority are received simultaneously, an internal polling sequence determines which request is serviced. Thus within

each priority level there is a second priority structure determined by the polling sequence as shown in Table 9.

Table 8

Interrupt Sources and their Corresponding Interrupt Vectors

Source (Request Flags)

Vector

Vector Address

IE0

TF0

IE1

TF1

RI+TI

TF2+EXF2

External interrupt 0

Timer 0 interrupt

External interrupt 1

Timer 1 interrupt

Serial port interrupt

Timer 2 interrupt

Table 9

Interrupt Priority-Within-Level

Interrupt Source

Priority

IE0

TF0

IE1

TF1

RI+TI

TF2+EXF2

External interrupt 0

Timer 0 interrupt

External interrupt 1

Timer 1 interrupt

Serial port interrupt

Timer 2 interrupt

High

↓

Low