基于i.MX6ULL的掉电检测设计与软件测试

基于i.MX6ULL的掉电检测设计与软件测试

基于i.MX6ULL平台设计实现掉电检测功能，首先选择一路IO，利用IO电平变化触发中断，在编写驱动时捕获该路GPIO的中断，然后在中断响应函数中发送信号通知应用程序掉电发生了。

图 1.1掉电信号IO

驱动代码:

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define power_MAJOR 200

static struct class *my_class;

static struct fasync_struct *fasync_queue; //异步通知队列

#define GPIO_NUM 1 //中断引脚为：GPIO1_1

static unsigned int irq_num;

/*打开 */

int power_open(struct inode *inode,struct file *filp){

return 0;

}

/*关闭 */

int power_release(struct inode *inode,struct file *filp){

return 0;

}

ssize_t power_read(struct file *filp,char __user *buf,size_t count,loff_t *f_pos){

return count;

}

ssize_t power_write(struct file *file,const char __user *buf,size_t count,loff_t *f_pos){

return count;

}

static int my_fasync(int fd, struct file * filp, int on)

{

int retval;

retval=fasync_helper(fd,filp,on,&fasync_queue);

/*将该设备登记到fasync_queue队列中去*/

if(retval<0)

return retval;

return 0;

}

static const struct file_operations simple_fops={

.owner=THIS_MODULE,

.open=power_open,

.release=power_release,

.read=power_read,

.write=power_write,

.fasync=my_fasync,

};

/*在中断服务函数中向应用层发送消息-异步通知 */

static irqreturn_t irq_callback (int irqno, void *dev_id){

printk("irq power-detect working !\n");

if (fasync_queue) {

kill_fasync(&fasync_queue, SIGIO, POLL_IN);

}

return IRQ_HANDLED;

}

int power_init_module(void){

int rtn;

int ret;

/*注册设备驱动 */

ret = register_chrdev(power_MAJOR,"power-detect-test",&simple_fops);

if(ret<0){

printk("Unable to register character device %d!/n",ret);

return ret;

}

/*自动创建设备节点 */

my_class = class_create(THIS_MODULE, "my_class");

device_create(my_class, NULL, MKDEV(power_MAJOR, 0), NULL,"powerdetect");

/*gpio申请*/

rtn = gpio_request(GPIO_NUM, "my_irq");

if(rtn!=0){

printk("my_irq irq pin request io failed.\n");

}

rtn = gpio_direction_input(GPIO_NUM);

if(rtn<0){

printk("gpio_direction_input() failed !\n");

}

/*获取gpio中断号*/

irq_num = gpio_to_irq(GPIO_NUM);

/*GPIO中断服务函数注册，*/ /*下降沿触发*/

rtn = request_irq(irq_num, irq_callback,IRQF_TRIGGER_FALLING,"my_irq", NULL);

if (rtn<0) {

printk("my_irq request irq false\n");

} else {

printk("my_irq request irq success: %d\n",irq_num);

}

printk("module_init sucessful!!!\n");

return 0;

}

/*卸载 */

void power_cleanup_module(void){

/*卸载相应的设备驱动 */

unregister_chrdev(power_MAJOR,"power-detect-test");

device_destroy(my_class,MKDEV(power_MAJOR, 0));

class_destroy(my_class);

/*释放GPIO*/

gpio_free(GPIO_NUM);

printk("module_exit sucessful!!!\n");

}

/*宏实现 */

module_init(power_init_module);

module_exit(power_cleanup_module);

/*开源许可声明 */

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Zou");

应用代码:

#include

#include

#include

#include

#include

#include

static int fd;

/*内核产生异步通知,调用该应用层函数处理 */

void sigterm_handler(int signo)

{

printf("app irq work !!!\n");

}

int main(void)

{

int oflags;

fd=open("/dev/powerdetect",O_RDWR); //打开设备文件

/*启动异步通知信号驱动机制 */

signal(SIGIO, sigterm_handler);

fcntl(fd, F_SETOWN, getpid());

oflags = fcntl(fd, F_GETFL);

fcntl(fd, F_SETFL, oflags | FASYNC);

/*建立一个死循环，防止程序结束 */

while(1)

{

printf("sleep\n");

usleep(200000); //2ms

}

close(fd);

return 0;

}

将驱动编译成模块，上电加载并执行应用程序后，将电压缓慢下调至掉电临界点。触发GPIO下降沿中断，并提供应用程序掉电信号。

图1..2掉电检测