Interrupt Request Detection; Interrupt Level Assigning; Interrupt Priority Assigning - Toshiba TMPR4925 Manual

15.3.2

Interrupt Request Detection

In order to perform interrupt detection, each register of the Interrupt Controller is initialized, then the
IDE bit of the Interrupt Detection Enable Register (IRDEN) is set to "1." All interrupts detected by the
Interrupt Controller are masked when this bit is cleared.
It is possible to set each interrupt factor detection mode using Interrupt Detection Mode Register 0
(IRDM0) and Interrupt Detection Mode Register 1 (IRDM1). There are four detection modes: Low
level, High level, falling edge, and rising edge.
The detected interrupt factors can be read out from the Interrupt Pending Register (IRPND).
15.3.3

Interrupt Level Assigning

Interrupt levels from 0 to 7 are assigned to each detected interrupt using the Interrupt Level Register
(IRLVL0-7). Interrupt level 7 is the highest priority and interrupt level1 is the lowest priority. Level 0
interrupts will be masked. (Table 15.3.2).
The priorities set by these interrupt levels will be given higher priority than the priorities provided
for each interrupt source indicated in Table 15.3.1.
15.3.4

Interrupt Priority Assigning

When multiple interrupt requests exist, the Interrupt Controller selects the interrupt with the highest
priority according to the priority level and interrupt number. Interrupt factors with an interrupt level
lower than the interrupt level specified by the Interrupt Mask Level Register (IRMSK) will be excluded
(masked).
When the interrupt with the highest priority is selected, then the interrupt number of that interrupt is
set in the interrupt factor field (CAUSE) of the Interrupt Current Status Register (IRCS), the interrupt
level is set in the Interrupt Level field (LVL), and the Interrupt Flag bit (IF) is set.
Chapter 15 Interrupt Controller
Table 15.3.2 Interrupt Levels
Interrupt Level
Priority
(IRLVLn.ILm)
High 111
110
101
100
011
010
Low 001
Mask 000
15-5