F407无法使用RTC，手册上的RTC实验例程跑不通。请各位不吝赐教！

发布于 2020-08-31 19:44:44 浏览：1621 订阅该版

今天在407上打算用RTC实现一个时间计时，各种配置后使用RT手册的RTC例程编译发现：
1.
```
static int rtc_sample(int argc, char *argv[])
{
    rt_err_t ret = RT_EOK;
    time_t now;
		
    /* 设置日期 */
    ret = set_date(2018, 12, 3);
    if (ret != RT_EOK)
    {
        rt_kprintf("set RTC date failed\n");
        return ret;
    }

/* 设置时间 */
    ret = set_time(11, 15, 50);
    if (ret != RT_EOK)
    {
        rt_kprintf("set RTC time failed\n");
        return ret;
    }

/* 延时3秒 */
    rt_thread_mdelay(3000);

/* 获取时间 */
    now = time(RT_NULL);
    rt_kprintf("%s\n", ctime(&now));

return ret;
}

```
这里报错"set RTC date failed\n"。然后发现是rt_device_find("rtc") 找不到RTC设备，使用list_device命令发现不存在RTC设备。于是手动进行设备注册
```
	RT_ASSERT(!rt_device_find("rtc"));
	if(RT_EOK != rt_device_register(&rtc_dev, "rtc", RT_DEVICE_FLAG_RDWR))
	{
		rt_kprintf("rt_device_register failed\n");
	}
	INIT_DEVICE_EXPORT(rt_rtc_init);
```
编译，list_device出现设备RTC，但继续报错：
2.
```
rt_err_t set_date(rt_uint32_t year, rt_uint32_t month, rt_uint32_t day)
{
    time_t now;
    struct tm *p_tm;
    struct tm tm_new;
    rt_device_t device;
    rt_err_t ret = -RT_ERROR;

/* get current time */
    now = time(RT_NULL);

/* lock scheduler. */
    rt_enter_critical();
    /* converts calendar time time into local time. */
    p_tm = localtime(&now);
    /* copy the statically located variable */
    memcpy(&tm_new, p_tm, sizeof(struct tm));
    /* unlock scheduler. */
    rt_exit_critical();

/* update date. */
    tm_new.tm_year = year - 1900;
    tm_new.tm_mon  = month - 1; /* tm_mon: 0~11 */
    tm_new.tm_mday = day;

/* converts the local time in time to calendar time. */
    now = mktime(&tm_new);

device = rt_device_find("rtc");
    if (device == RT_NULL)
    {
        return -RT_ERROR;
    }

/* update to RTC device. */
    ret = rt_device_control(device, RT_DEVICE_CTRL_RTC_SET_TIME, &now);
	rt_kprintf("4.rt_device_control==%d \n",ret);
    return ret;
}
```
发现是该函数最后一行：“ ret = rt_device_control(device, RT_DEVICE_CTRL_RTC_SET_TIME, &now);”返回异常，于是发现是由于该函数内的
```
    /* call device_write interface */
    if (device_control != RT_NULL)
    {
		rt_kprintf("5.device_control==%d \n",device_control(dev, cmd, arg));
        return device_control(dev, cmd, arg);
    }
```
device_control为NULL，即上面函数的设备参数dev->control为NULL，该参数是在set_date里面调用
```
rt_device_control(device, RT_DEVICE_CTRL_RTC_SET_TIME, &now)
```
时传入的，于是接下来在调用之前把设备参数进行手动初始化。手动为
```    
    rtc_dev.type     = RT_Device_Class_RTC;    /**< RTC device */
    /* register rtc device */
    soft_rtc_dev.ops     = &soft_rtc_ops;
    rtc_dev.init    = RT_NULL;
    rtc_dev.open    = RT_NULL;
    rtc_dev.close   = RT_NULL;
    rtc_dev.read    = RT_NULL;
    rtc_dev.write   = RT_NULL;
    rtc_dev.control = rtc_control;
    rtc_dev.user_data = RT_NULL;
```
其中，将rtc_control设置为
```
rtc_control(rt_device_t dev, int cmd, void *args)
{return RT_EOK;}
```
此时编译通过，运行正常。但是时间永远是1970-01-01-00-00-00. 
研究发现，这应该是
```
ret = rt_device_control(device, RT_DEVICE_CTRL_RTC_SET_TIME, &now);
```
里面的第二个参数没有起作用，该参数应该在
```
rtc_control(rt_device_t dev, int cmd, void *args)
```
进行处理，而我设置成了空函数。靠！QTQ。
后来把sort_rtc里面的sort_rtc_control函数搬过来
```
static rt_err_t rtc_control(rt_device_t dev, int cmd, void *args)
{
    time_t *time;
    struct tm time_temp;

RT_ASSERT(dev != RT_NULL);
    memset(&time_temp, 0, sizeof(struct tm));	
    switch (cmd)
    {
    case RT_DEVICE_CTRL_RTC_GET_TIME:
        time = (time_t *) args;
        *time = init_time + (rt_tick_get() - init_tick) / RT_TICK_PER_SECOND;
        break;

case RT_DEVICE_CTRL_RTC_SET_TIME:
    {
        time = (time_t *) args;
        init_time = *time - (rt_tick_get() - init_tick) / RT_TICK_PER_SECOND;
        break;
    }
    }

return RT_EOK;
}
```
编译运行成功，时间可以变化了。然而，断电重启407后，时间又回到了初始化的时间。

静下来思考发现，想不通：明明我是用的407的片上RTC，并且VBAT引脚电池有电，为什么手册上的RTC例程会上来就找不到‘rtc’设备呢？注册了设备又为什么开始在set_date这里就一路报错呢？请各位不吝赐教！

附上例程链接：[RTC例程](https://www.rt-thread.org/document/site/programming-manual/device/rtc/rtc/)

以下为RTthread配置：
CubeMX
![image.png](/uploads/20200831/bcda55ad8f6aac45b2ac2ed92dd935ec.png)

![image.png](/uploads/20200831/f48029abd2e2c184ffdcba0840e823a2.png)

![image.png](/uploads/20200831/75722c9fe0a8808722acb3562e659d74.png)

Menuconfig
![image.png](/uploads/20200831/7b68a846ab546e9824143b69b96a0f2e.png)

![image.png](/uploads/20200831/4b6478ef0e84a1f2656415f0da1df3a7.png)

![image.png](/uploads/20200831/e1e2ca99280f1eb441a2c7e949b34976.png)

![image.png](/uploads/20200831/c0f1bcdb0f621a7b06ed0e27df999a4b.png)