Fujitsu FR81S User Manual
CHAPTER 12: INTERRUPT CONTROL (INTERRUPT
CONTROLLER)
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: INTERRUPT CONTROL (INTERRUPT CONTROLLER)
FUJITSU SEMICONDUCTOR CONFIDENTIAL
11
5.3. Determining Priorities
The determining priorities is shown below.
This module selects the highest priority interrupt among interrupt factors that occur simultaneously and
outputs the interrupt level and interrupt vector number for the interrupt factors to the CPU.
The criteria for determining the priority of interrupt factors are as follows.
1. NMI
2. Factors that meet the following conditions
- If the value of the interrupt level is not 31 (5’b11111). (31 indicates interrupts disabled)
- The factors where the value of the interrupt level is the smallest.
- When the interrupt level is the same (except for 31), the factors that has the smallest interrupt vector number
from amongst these.
If no interrupt factors is selected by the above criteria, 31 (5’b11111) is output as the interrupt level. The
interrupt vector number at this time is undefined.
MB91520 Series
MN705-00010-1v0-E
472