Tick interface（心跳接口）

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LVGL needs a system tick to know elapsed time for animations and other tasks.

You need to call the lv_tick_inc(tick_period) function periodically and provide the call period in milliseconds. For example, lv_tick_inc(1) when calling every millisecond.

lv_tick_inc should be called in a higher priority routine than lv_task_handler() (e.g. in an interrupt) to precisely know the elapsed milliseconds even if the execution of lv_task_handler takes more time.

With FreeRTOS lv_tick_inc can be called in vApplicationTickHook.

On Linux based operating system (e.g. on Raspberry Pi) lv_tick_inc can be called in a thread like below:

LVGL 需要一个系统滴答来了解动画和其他任务所用的时间。

您需要定期调用 lv_tick_inc(tick_period) 函数并提供以毫秒为单位的调用周期。例如，lv_tick_inc(1) 每毫秒调用一次。

lv_tick_inc 应该在比 lv_task_handler() 更高优先级的例程中调用（例如在中断中），以精确知道经过的毫秒数，即使 lv_task_handler 的执行需要更多时间。

使用 FreeRTOS，可以在 vApplicationTickHook 中调用 lv_tick_inc。

在基于 Linux 的操作系统（例如在 Raspberry Pi 上）可以在如下线程中调用 lv_tick_inc：

void * tick_thread (void *args)
{
      while(1) {
        usleep(5*1000);   /*Sleep for 5 millisecond*/
        lv_tick_inc(5);      /*Tell LVGL that 5 milliseconds were elapsed*/
    }
}

API

Provide access to the system tick with 1 millisecond resolution

Functions

uint32_t lv_tick_get(void)

Get the elapsed milliseconds since start up

返回

the elapsed milliseconds

uint32_t lv_tick_elaps(uint32_t prev_tick)

Get the elapsed milliseconds since a previous time stamp

参数

prev_tick -- a previous time stamp (return value of lv_tick_get() )

返回

the elapsed milliseconds since 'prev_tick'