# PLIC

## Overview

The PLIC example uses ptpc(or gptmr)/gpio/plicsw interrupts to shows interrupt nesting function.

ptpc(or gptmr) isr will not finish until gpio interrupt is triggered 5 times. Meanwhile in gpio isr, software interrupt will be triggered as well.

## Board Setting

No special settings are required

## Running the example

Running the example, interrupt nesting will occur when pressing GPIO button (please check [Button](lab_board_resource) section of specific board) according to the log prompt. The following message is displayed in the terminal:
```console
Machine mode (Vector Preemptive) interrupt test
Press button will trigger GPIO interrupt, in which software interrupt will be triggered as well.
ptpc(or gptmr) interrupt start
+ now next 5 gpio interrupts will occur in nested irq context
gpio interrupt start
plicsw start
plicsw end
gpio interrupt end
```