怎么使用pcDuino的外部中断
本篇文章给大家分享的是有关怎么使用pcDuino的外部中断，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。
按键中断-poll机制
我们尝试让按键具有这样一种功能，如果一定的时间内没有人去按按键，内核就提醒一下，然后我们应用程序得到提醒之后打印time out。
驱动程序
#include
#include
#include
#include
#include
#include
#include
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#include
#include
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#include
//#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define GPIO_IRQ 28
#define GPIO_TEST_BASE 0xf1c20800
#define PH_CFG2 (GPIO_TEST_BASE + 0x104)
#define PIO_INT_CFG2 (GPIO_TEST_BASE+ 0x208)
#define PIO_INT_CTL (GPIO_TEST_BASE+ 0x210)
#define PH17_SELECT (6 << 4)
#define PH18_SELECT (6 << 8)
#define PH19_SELECT (6 << 12)
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
/* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */
static volatile int ev_press = 0;
static struct class *keydrv_class;
static unsigned int status;
static irqreturn_t key_irq(int irq, void *dev_id)
{
status =readl(GPIO_TEST_BASE + 0x214 ) ;
ev_press = 1; /* 表示中断发生了 */
wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
writel(status,GPIO_TEST_BASE + 0x214);
return IRQ_HANDLED;
}
static int key_drv_open(struct inode *inode, struct file *file)
{
int error;
int irq_ctl;
/*1,设置中断位*/
irq_ctl =readl(PH_CFG2);
writel(PH19_SELECT|PH17_SELECT|PH18_SELECT| irq_ctl ,PH_CFG2);
/*2,设置中断方式*/
irq_ctl =readl(PIO_INT_CFG2);
writel((0x4<<(1*4))|(0x4 <<(2*4))|(0x4 <<(3*4)) | irq_ctl,PIO_INT_CFG2);
/*3,开中断*/
irq_ctl =readl(PIO_INT_CTL);
writel((0xf <<16)|irq_ctl,PIO_INT_CTL);
error =request_irq(GPIO_IRQ, key_irq,0, "button", 1);
if (error) {
printk("failed toregister keypad interrupt\n");
}
printk(KERN_ALERT"keyopeni\n");
return 0;
}
static unsigned key_drv_poll(struct file *file, poll_table *wait)
{
unsigned int mask = 0;
poll_wait(file,&button_waitq, wait); // 不会立即休眠
if (ev_press)
mask |=POLLIN | POLLRDNORM;
return mask;
}
ssize_t key_drv_read(struct file *file, char __user *buf, size_tsize, loff_t *ppos)
{
/* 如果没有按键动作, 休眠 */
wait_event_interruptible(button_waitq,ev_press);
/* 如果有按键动作, 返回键值 */
copy_to_user(buf,&status, sizeof(unsigned int));
ev_press = 0;
return 1;
}
static ssize_t key_drv_write(struct file *file, const char __user*buf, size_t count, loff_t * ppos)
{
printk(KERN_ALERT"keywrite\n");
return 0;
}
int key_drv_close(struct inode *inode, struct file *file)
{
free_irq(GPIO_IRQ,1);
return 0;
}
static struct file_operations key_drv_fops = {
.owner = THIS_MODULE, /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
.open = key_drv_open,
.write = key_drv_write,
.read = key_drv_read,
.release = key_drv_close,
.poll = key_drv_poll,
};
int major;
static int key_drv_init(void)
{
major =register_chrdev(0, "key_drv", &key_drv_fops);
keydrv_class =class_create(THIS_MODULE,"key_drv");
device_create(keydrv_class,NULL,MKDEV(major,0),NULL,"key");
printk(KERN_ALERT"register\n");
return 0;
}
static void key_drv_exit(void)
{
unregister_chrdev(major,"key_drv"); // 卸载
device_destroy(keydrv_class,MKDEV(major,0));
class_destroy(keydrv_class);
printk(KERN_ALERT"unregister\n");
}
module_init(key_drv_init);
module_exit(key_drv_exit);
MODULE_LICENSE("GPL");
测试程序 test_key.c (706 Bytes, 下载次数: 0, 售价: 5 金钱) ：
#include
#include
#include
int kbit = 0;
void PrintBinary(unsigned int c)
{
if (c>>1)PrintBinary(c>>1);
printf("%d:%d",kbit, c&1);
kbit++;
}
int main()
{
int fd;
unsigned int val = 1;
int ret;
struct pollfd fds[1];
fd =open("/dev/key",0666);
if(fd < 0)
{
printf("cannotopen\n");
return 0;
}
fds[0].fd = fd;
fds[0].events =POLLIN;
while(1)
{
kbit = 0;
ret =poll(fds, 1, 5000);
if (ret ==0)
{
printf("timeout\n");
}
else
{
read(fd,&val,sizeof(unsignedint));
PrintBinary(val);
if(val&(1<<17))printf("Back\n");
if(val&(1<<18))printf("home\n");
if(val&(1<<19))printf("menu\n");
}
}
close(fd);
return 0;
}
编译：
gcc test_key.c
测试：
root @ubuntu :/home/ubuntu/driver/key_02# ./a.out
[10049.740000] key openi
0:1 1:0 2:0 3:0 4:0 5:0 6:0 7:0 8:0 9:0 10:0 11:0 12:0 13:0 14:015:0 16:0 17:0 18:0 home
0:1 1:0 2:0 3:0 4:0 5:0 6:0 7:0 8:0 9:0 10:0 11:0 12:0 13:0 14:015:0 16:0 17:0 18:0 home
time out
time out
time out
time out
0:1 1:0 2:0 3:0 4:0 5:0 6:0 7:0 8:0 9:0 10:0 11:0 12:0 13:0 14:015:0 16:0 17:0 Back
0:1 1:0 2:0 3:0 4:0 5:0 6:0 7:0 8:0 9:0 10:0 11:0 12:0 13:0 14:015:0 16:0 17:0 Back
以上就是怎么使用pcDuino的外部中断，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注行业资讯频道。
