「App:Library:LVGL:docs:Porting:Operating system and interrupts」の版間の差分

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== Tasks and threads ==
 
== Tasks and threads ==
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{| class="wikitable"
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!英文
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!自動翻訳
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If you need to use real tasks or threads, you need a mutex which should be invoked before the call of <code style="color: #bb0000;">lv_timer_handler</code> and released after it. Also, you have to use the same mutex in other tasks and threads around every LVGL (<code style="color: #bb0000;">lv_...</code>) related function call and code. This way you can use LVGL in a real multitasking environment. Just make use of a mutex to avoid the concurrent calling of LVGL functions.
 
If you need to use real tasks or threads, you need a mutex which should be invoked before the call of <code style="color: #bb0000;">lv_timer_handler</code> and released after it. Also, you have to use the same mutex in other tasks and threads around every LVGL (<code style="color: #bb0000;">lv_...</code>) related function call and code. This way you can use LVGL in a real multitasking environment. Just make use of a mutex to avoid the concurrent calling of LVGL functions.
  
 
Here is some pseudocode to illustrate the concept:
 
Here is some pseudocode to illustrate the concept:
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<syntaxhighlight lang="C++">
 
  static mutex_t lvgl_mutex;
 
  static mutex_t lvgl_mutex;
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<syntaxhighlight lang="C++">
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  void lvgl_thread(void)
 
  void lvgl_thread(void)
 
  {
 
  {

2022年6月22日 (水) 14:36時点における版

https://docs.lvgl.io/8.2/porting/os.html

英文 自動翻訳


Operating system and interrupts

LVGL is not thread-safe by default.

However, in the following conditions it's valid to call LVGL related functions:

  • In events. Learn more in Events.
  • In lv_timer. Learn more in Timers.


Tasks and threads

英文 自動翻訳

If you need to use real tasks or threads, you need a mutex which should be invoked before the call of lv_timer_handler and released after it. Also, you have to use the same mutex in other tasks and threads around every LVGL (lv_...) related function call and code. This way you can use LVGL in a real multitasking environment. Just make use of a mutex to avoid the concurrent calling of LVGL functions.

Here is some pseudocode to illustrate the concept: 

 static mutex_t lvgl_mutex;

 void lvgl_thread(void)
 {
     while(1) {
         mutex_lock(&lvgl_mutex);
         lv_task_handler();
         mutex_unlock(&lvgl_mutex);
         thread_sleep(10); /* sleep for 10 ms */
     }
 }
 
 void other_thread(void)
 {
     /* You must always hold the mutex while using LVGL APIs */
     mutex_lock(&lvgl_mutex);
     lv_obj_t *img = lv_img_create(lv_scr_act());
     mutex_unlock(&lvgl_mutex);
     
     while(1) {
         mutex_lock(&lvgl_mutex);
         /* change to the next image */
         lv_img_set_src(img, next_image);
         mutex_unlock(&lvgl_mutex);
         thread_sleep(2000);
     }
 }

Interrupts

Try to avoid calling LVGL functions from interrupt handlers (except lv_tick_inc() and lv_disp_flush_ready()). But if you need to do this you have to disable the interrupt which uses LVGL functions while lv_timer_handler is running.

It's a better approach to simply set a flag or some value in the interrupt, and periodically check it in an LVGL timer (which is run by lv_timer_handler).




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