无法在定时器中使用rt_spi_send函数

发布于 2022-05-12 12:02:41 浏览：671 订阅该版

crystal266 2022-05-12

嵌入式

`rt_thread_delay_until` 这个函数是 RT-Thread 的绝对延时函数，可以使用 绝对延时函数 + 线程优先级最高 进行实现

![微信截图_20220512141113.png](https://oss-club.rt-thread.org/uploads/20220512/5ffa742c115b29b09ac00017c5d55ef0.png)

```c
/**
 * @brief   This function will let current thread delay until (*tick + inc_tick).
 *
 * @param   tick is the tick of last wakeup.
 *
 * @param   inc_tick is the increment tick.
 *
 * @return  Return the operation status. If the return value is RT_EOK, the function is successfully executed.
 *          If the return value is any other values, it means this operation failed.
 */
rt_err_t rt_thread_delay_until(rt_tick_t *tick, rt_tick_t inc_tick)
{
    register rt_base_t level;
    struct rt_thread *thread;
    rt_tick_t cur_tick;

RT_ASSERT(tick != RT_NULL);

/* set to current thread */
    thread = rt_thread_self();
    RT_ASSERT(thread != RT_NULL);
    RT_ASSERT(rt_object_get_type((rt_object_t)thread) == RT_Object_Class_Thread);

/* disable interrupt */
    level = rt_hw_interrupt_disable();

cur_tick = rt_tick_get();
    if (cur_tick - *tick < inc_tick)
    {
        rt_tick_t left_tick;

*tick += inc_tick;
        left_tick = *tick - cur_tick;

/* suspend thread */
        rt_thread_suspend(thread);

/* reset the timeout of thread timer and start it */
        rt_timer_control(&(thread->thread_timer), RT_TIMER_CTRL_SET_TIME, &left_tick);
        rt_timer_start(&(thread->thread_timer));

/* enable interrupt */
        rt_hw_interrupt_enable(level);

rt_schedule();

/* clear error number of this thread to RT_EOK */
        if (thread->error == -RT_ETIMEOUT)
        {
            thread->error = RT_EOK;
        }
    }
    else
    {
        *tick = cur_tick;
        rt_hw_interrupt_enable(level);
    }

return RT_EOK;
}
RTM_EXPORT(rt_thread_delay_until);
```