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51 lines
1.7 KiB
Markdown
51 lines
1.7 KiB
Markdown
2 years ago
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# Operating system and interrupts
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LVGL is **not thread-safe** by default.
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However, in the following conditions it's valid to call LVGL related functions:
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- In *events*. Learn more in [Events](/overview/event).
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- In *lv_timer*. Learn more in [Timers](/overview/timer).
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## Tasks and threads
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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 `lv_timer_handler` and released after it.
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Also, you have to use the same mutex in other tasks and threads around every LVGL (`lv_...`) related function call and code.
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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.
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Here is some pseudocode to illustrate the concept:
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```c
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static mutex_t lvgl_mutex;
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void lvgl_thread(void)
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{
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while(1) {
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mutex_lock(&lvgl_mutex);
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lv_task_handler();
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mutex_unlock(&lvgl_mutex);
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thread_sleep(10); /* sleep for 10 ms */
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}
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}
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void other_thread(void)
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{
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/* You must always hold the mutex while using LVGL APIs */
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mutex_lock(&lvgl_mutex);
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lv_obj_t *img = lv_img_create(lv_scr_act());
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mutex_unlock(&lvgl_mutex);
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while(1) {
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mutex_lock(&lvgl_mutex);
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/* change to the next image */
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lv_img_set_src(img, next_image);
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mutex_unlock(&lvgl_mutex);
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thread_sleep(2000);
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}
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}
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```
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## Interrupts
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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.
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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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