NIOSII按键中断实验

接着在上一个NIOSII流水灯实验的基础上进行了一个按键中断控制流水灯的实验,增加一个按键开关PIO（only input）：按一下开关，四个灯开始循环点亮；再按一下开关，四个灯停止点亮，全熄灭。

头文件SOPC.h

#ifndef SOPC_H_

#define SOPC_H_



#include "system.h"

#define _LED

#define _KEY



typedef struct

{

    unsigned long int DATA;

    unsigned long int DIRECTION;

    unsigned long int INRERRUPT_MASK;

    unsigned long int EDGE_CAPTURE;

}PIO_STR;



#ifdef _LED

#define LED ((PIO_STR*)LED_BASE)

#endif



#ifdef _KEY

#define KEY ((PIO_STR*)KEY_BASE)

#endif



#endif /*SOPC_H_*/

/*

 * "Hello World" example.

 *

 * This example prints 'Hello from Nios II' to the STDOUT stream. It runs on

 * the Nios II 'standard', 'full_featured', 'fast', and 'low_cost' example

 * designs. It runs with or without the MicroC/OS-II RTOS and requires a STDOUT

 * device in your system's hardware.

 * The memory footprint of this hosted application is ~69 kbytes by default

 * using the standard reference design.

 *

 * For a reduced footprint version of this template, and an explanation of how

 * to reduce the memory footprint for a given application, see the

 * "small_hello_world" template.

 *

 */



#include <stdio.h>

#include<unistd.h>



#include"../inc/sopc.h"

#include"system.h"

#include"sys/alt_irq.h"



int key_flag =0;

void ISR_key(void*context,unsigned long id)

{

    key_flag = ~key_flag;

    usleep(500000);

}



int init_key(void)

{

    KEY->INRERRUPT_MASK =1;

    

    return alt_irq_register(KEY_IRQ,NULL,ISR_key);

}



int main()

{

  int i;

  if(!init_key())

  {

    printf("register successfully!\n");

  }

   else

    {

       printf("Error:register failure!\n"); 

    }

   while(1)

   {

    if(key_flag)

    {

        for(i=0;i<4;i++)

        {

            LED->DATA=1<<i;

            usleep(500000);

        }

        

    }

    else

    {

        LED->DATA=0;

        

    }

   }

   return 0;

}

在NIOSII中若用电平中断，则要注意它只对高电平敏感，若想实现低电平敏感则要加一个非门。